You can find below the publication list of all members of the theoretical chemistry group at ENS. For the list of each individual member, please consult their personal webpage from the Members page.
2020 |
Protein Preferential Solvation in Water:Glycerol Mixtures Article de journal Nicolas Chéron; Margaux Naepels; Eva Pluhařová; Damien Laage The Journal of Physical Chemistry B, 124 (8), p. 1424-1437, 2020. @article{doi:10.1021/acs.jpcb.9b11190, title = {Protein Preferential Solvation in Water:Glycerol Mixtures}, author = {Nicolas Ch\'{e}ron and Margaux Naepels and Eva Pluha\v{r}ov\'{a} and Damien Laage}, url = {https://doi.org/10.1021/acs.jpcb.9b11190}, doi = {10.1021/acs.jpcb.9b11190}, year = {2020}, date = {2020-01-01}, journal = {The Journal of Physical Chemistry B}, volume = {124}, number = {8}, pages = {1424-1437}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
2019 |
Solvent effects on the vibrational spectrum of 3-hydroxyflavone Article de journal A P Seitsonen; A Idrissi; S Protti; A Mezzetti Journal of Molecular Liquids, 275 , p. 723–728, 2019. @article{Seitsonen:2019, title = {Solvent effects on the vibrational spectrum of 3-hydroxyflavone}, author = {A P Seitsonen and A Idrissi and S Protti and A Mezzetti}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057841646&doi=10.1016%2fj.molliq.2018.11.020&partnerID=40&md5=21ae25517ffabf644cd8eb8d94d34435}, doi = {10.1016/j.molliq.2018.11.020}, year = {2019}, date = {2019-01-01}, journal = {Journal of Molecular Liquids}, volume = {275}, pages = {723--728}, abstract = {3-hydroxyflavone (3HF) is a widely studied molecule that acts as a simplified prototype of biological, more complex flavonoids. Its solvation mechanism is still under investigation. Here we report a joint experimental and simulation study of the vibrational properties of 3HF in gas phase and in simple liquids tetrachloromethane, chloroform and acetonitrile using infra-red (IR) and Raman spectroscopies. We find reasonably good agreement between the static and molecular dynamics simulations employing density functional theory at the level of generalised gradient approximation (GGA) and hybrid functionals, but the agreement with the experimental spectra is only reasonable in the case of the IR spectroscopy and relatively poor in the case of Raman spectroscopy. The results can, however, be used as a starting point for discussing the solvation behaviour of the flavonoids. © 2018}, keywords = {}, pubstate = {published}, tppubtype = {article} } 3-hydroxyflavone (3HF) is a widely studied molecule that acts as a simplified prototype of biological, more complex flavonoids. Its solvation mechanism is still under investigation. Here we report a joint experimental and simulation study of the vibrational properties of 3HF in gas phase and in simple liquids tetrachloromethane, chloroform and acetonitrile using infra-red (IR) and Raman spectroscopies. We find reasonably good agreement between the static and molecular dynamics simulations employing density functional theory at the level of generalised gradient approximation (GGA) and hybrid functionals, but the agreement with the experimental spectra is only reasonable in the case of the IR spectroscopy and relatively poor in the case of Raman spectroscopy. The results can, however, be used as a starting point for discussing the solvation behaviour of the flavonoids. © 2018 |
Benzimidazoles as Metal-Free and Recyclable Hydrides for CO2 Reduction to Formate Article de journal C -H Lim; S Ilic; A Alherz; B T Worrell; S S Bacon; J T Hynes; K D Glusac; C B Musgrave Journal of the American Chemical Society, 141 (1), p. 272–280, 2019. @article{Lim:2019, title = {Benzimidazoles as Metal-Free and Recyclable Hydrides for CO2 Reduction to Formate}, author = {C -H Lim and S Ilic and A Alherz and B T Worrell and S S Bacon and J T Hynes and K D Glusac and C B Musgrave}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058544348&doi=10.1021%2fjacs.8b09653&partnerID=40&md5=538b0ec89a42c986b6e46df1217fc701}, doi = {10.1021/jacs.8b09653}, year = {2019}, date = {2019-01-01}, journal = {Journal of the American Chemical Society}, volume = {141}, number = {1}, pages = {272--280}, abstract = {We report a novel metal-free chemical reduction of CO2 by a recyclable benzimidazole-based organo-hydride, whose choice was guided by quantum chemical calculations. Notably, benzimidazole-based hydride donors rival the hydride-donating abilities of noble-metal-based hydrides such as [Ru(tpy)(bpy)H]+ and [Pt(depe)2H]+. Chemical CO2 reduction to the formate anion (HCOO-) was carried out in the absence of biological enzymes, a sacrificial Lewis acid, or a base to activate the substrate or reductant. 13CO2 experiments confirmed the formation of H13COO- by CO2 reduction with the formate product characterized by 1H NMR and 13C NMR spectroscopy and ESI-MS. The highest formate yield of 66% was obtained in the presence of potassium tetrafluoroborate under mild conditions. The likely role of exogenous salt additives in this reaction is to stabilize and shift the equilibrium toward the ionic products. After CO2 reduction, the benzimidazole-based hydride donor was quantitatively oxidized to its aromatic benzimidazolium cation, establishing its recyclability. In addition, we electrochemically reduced the benzimidazolium cation to its organo-hydride form in quantitative yield, demonstrating its potential for electrocatalytic CO2 reduction. These results serve as a proof of concept for the electrocatalytic reduction of CO2 by sustainable, recyclable, and metal-free organo-hydrides. © 2018 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We report a novel metal-free chemical reduction of CO2 by a recyclable benzimidazole-based organo-hydride, whose choice was guided by quantum chemical calculations. Notably, benzimidazole-based hydride donors rival the hydride-donating abilities of noble-metal-based hydrides such as [Ru(tpy)(bpy)H]+ and [Pt(depe)2H]+. Chemical CO2 reduction to the formate anion (HCOO-) was carried out in the absence of biological enzymes, a sacrificial Lewis acid, or a base to activate the substrate or reductant. 13CO2 experiments confirmed the formation of H13COO- by CO2 reduction with the formate product characterized by 1H NMR and 13C NMR spectroscopy and ESI-MS. The highest formate yield of 66% was obtained in the presence of potassium tetrafluoroborate under mild conditions. The likely role of exogenous salt additives in this reaction is to stabilize and shift the equilibrium toward the ionic products. After CO2 reduction, the benzimidazole-based hydride donor was quantitatively oxidized to its aromatic benzimidazolium cation, establishing its recyclability. In addition, we electrochemically reduced the benzimidazolium cation to its organo-hydride form in quantitative yield, demonstrating its potential for electrocatalytic CO2 reduction. These results serve as a proof of concept for the electrocatalytic reduction of CO2 by sustainable, recyclable, and metal-free organo-hydrides. © 2018 American Chemical Society. |
Exciting vibrons in both frontier orbitals of a single hydrocarbon molecule on graphene Article de journal A Mehler; N Néel; M -L Bocquet; J Kröger Journal of Physics Condensed Matter, 31 (6), 2019. @article{Mehler:2019, title = {Exciting vibrons in both frontier orbitals of a single hydrocarbon molecule on graphene}, author = {A Mehler and N N\'{e}el and M -L Bocquet and J Kr\"{o}ger}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059370411&doi=10.1088%2f1361-648X%2faaf54c&partnerID=40&md5=5e541bf52c4692cc6d0c4ff3a4b4ec67}, doi = {10.1088/1361-648X/aaf54c}, year = {2019}, date = {2019-01-01}, journal = {Journal of Physics Condensed Matter}, volume = {31}, number = {6}, abstract = {Vibronic excitations in molecules are key to the fundamental understanding of the interaction between vibrational and electronic degrees of freedom. In order to probe the genuine vibronic properties of a molecule even after its adsorption on a surface appropriate buffer layers are of paramount importance. Here, vibrational progression in both molecular frontier orbitals is observed with submolecular resolution on a graphene-covered metal surface using scanning tunnelling spectroscopy. Accompanying calculations demonstrate that the vibrational modes that cause the orbital replica in the progression share the same symmetry as the electronic states they couple to. In addition, the vibrational progression is more pronounced for separated molecules than for molecules embedded in molecular assemblies. The entire vibronic spectra of these molecular species are moreover rigidly shifted with respect to each other. This work unravels intramolecular changes in the vibronic and electronic structure owing to the efficient reduction of the molecule-metal hybridization by graphene. © 2018 IOP Publishing Ltd.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Vibronic excitations in molecules are key to the fundamental understanding of the interaction between vibrational and electronic degrees of freedom. In order to probe the genuine vibronic properties of a molecule even after its adsorption on a surface appropriate buffer layers are of paramount importance. Here, vibrational progression in both molecular frontier orbitals is observed with submolecular resolution on a graphene-covered metal surface using scanning tunnelling spectroscopy. Accompanying calculations demonstrate that the vibrational modes that cause the orbital replica in the progression share the same symmetry as the electronic states they couple to. In addition, the vibrational progression is more pronounced for separated molecules than for molecules embedded in molecular assemblies. The entire vibronic spectra of these molecular species are moreover rigidly shifted with respect to each other. This work unravels intramolecular changes in the vibronic and electronic structure owing to the efficient reduction of the molecule-metal hybridization by graphene. © 2018 IOP Publishing Ltd. |
Spin in a Closed-Shell Organic Molecule on a Metal Substrate Generated by a Sigmatropic Reaction Article de journal M -L Bocquet; N Lorente; R Berndt; M Gruber Angewandte Chemie - International Edition, 58 (3), p. 821–824, 2019. @article{Bocquet:2019, title = {Spin in a Closed-Shell Organic Molecule on a Metal Substrate Generated by a Sigmatropic Reaction}, author = {M -L Bocquet and N Lorente and R Berndt and M Gruber}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058418932&doi=10.1002%2fanie.201812121&partnerID=40&md5=c9d1bd9afea90765f3df231c03cd706d}, doi = {10.1002/anie.201812121}, year = {2019}, date = {2019-01-01}, journal = {Angewandte Chemie - International Edition}, volume = {58}, number = {3}, pages = {821--824}, abstract = {Inert metal surfaces present more chances of hosting organic intact radicals than other substrates, but large amounts of delocalized electronic states favor charge transfer and thus spin quenching. Lowering the molecule\textendashsubstrate interaction is a usual strategy to stabilize radicals on surfaces. In some works, thin insulating layers were introduced to provide a controllable degree of electronic decoupling. Recently, retinoid molecules adsorbed on gold have been manipulated with a scanning tunneling microscope (STM) to exhibit a localized spin, but calculations failed to find a radical derivative of the molecule on the surface. Now the formation of a neutral radical spatially localized in a tilted and lifted cyclic end of the molecule is presented. An allene moiety provokes a perpendicular tilt of the cyclic end relative to the rest of the conjugated chain, thus localizing the spin of the dehydrogenated allene in its lifted subpart. DFT calculations and STM manipulations give support to the proposed mechanism. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim}, keywords = {}, pubstate = {published}, tppubtype = {article} } Inert metal surfaces present more chances of hosting organic intact radicals than other substrates, but large amounts of delocalized electronic states favor charge transfer and thus spin quenching. Lowering the molecule–substrate interaction is a usual strategy to stabilize radicals on surfaces. In some works, thin insulating layers were introduced to provide a controllable degree of electronic decoupling. Recently, retinoid molecules adsorbed on gold have been manipulated with a scanning tunneling microscope (STM) to exhibit a localized spin, but calculations failed to find a radical derivative of the molecule on the surface. Now the formation of a neutral radical spatially localized in a tilted and lifted cyclic end of the molecule is presented. An allene moiety provokes a perpendicular tilt of the cyclic end relative to the rest of the conjugated chain, thus localizing the spin of the dehydrogenated allene in its lifted subpart. DFT calculations and STM manipulations give support to the proposed mechanism. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim |
Circular dichroism and angular deviation in x-ray absorption spectra of Dy2ScN@ C80 single-molecule magnets on h-BN/Rh(111) Article de journal T Greber; A P Seitsonen; A Hemmi; J Dreiser; R Stania; F Matsui; M Muntwiler; A A Popov; R Westerström Physical Review Materials, 3 (1), 2019. @article{Greber:2019, title = {Circular dichroism and angular deviation in x-ray absorption spectra of Dy2ScN@ C80 single-molecule magnets on h-BN/Rh(111)}, author = {T Greber and A P Seitsonen and A Hemmi and J Dreiser and R Stania and F Matsui and M Muntwiler and A A Popov and R Westerstr\"{o}m}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060612538&doi=10.1103%2fPhysRevMaterials.3.014409&partnerID=40&md5=b74a780f93dca9f124b95bcec5c689dc}, doi = {10.1103/PhysRevMaterials.3.014409}, year = {2019}, date = {2019-01-01}, journal = {Physical Review Materials}, volume = {3}, number = {1}, abstract = {Endohedral fullerenes, such as Dy2ScN@C80, are single-molecule magnets with long relaxation times of their magnetization. An open and anisotropic 4f electron shell in the lanthanides (here Dy) imposes a magnetic moment that maintains its orientation at liquid-helium temperatures for macroscopic times. If these molecules shall be used as single-bit information storage elements or for quantum operations, the orientation of the endohedral units and the orientation of the magnetic moments has to be controlled. X-ray absorption spectroscopy (XAS) and magnetic circular dichroism (XMCD) - with variation of the angle of x-ray incidence - allows for the detection of these two structural elements. We present XMCD data of Dy2ScN@C80 on an h-BN/Rh(111) nanomesh that display at 2 K a large hysteresis with a coercive field of 0.4 T. The angular dependence of the XAS data at the Dy M5 edge indicates partial ordering of the endohedral units. In order to quantify anisotropic orientation we introduce the "deviation" D as an operational quantity that measures differences between two spectra. © 2019 American Physical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Endohedral fullerenes, such as Dy2ScN@C80, are single-molecule magnets with long relaxation times of their magnetization. An open and anisotropic 4f electron shell in the lanthanides (here Dy) imposes a magnetic moment that maintains its orientation at liquid-helium temperatures for macroscopic times. If these molecules shall be used as single-bit information storage elements or for quantum operations, the orientation of the endohedral units and the orientation of the magnetic moments has to be controlled. X-ray absorption spectroscopy (XAS) and magnetic circular dichroism (XMCD) - with variation of the angle of x-ray incidence - allows for the detection of these two structural elements. We present XMCD data of Dy2ScN@C80 on an h-BN/Rh(111) nanomesh that display at 2 K a large hysteresis with a coercive field of 0.4 T. The angular dependence of the XAS data at the Dy M5 edge indicates partial ordering of the endohedral units. In order to quantify anisotropic orientation we introduce the "deviation" D as an operational quantity that measures differences between two spectra. © 2019 American Physical Society. |
2018 |
Water Dynamics in Concentrated Electrolytes: Local Ion Effect on Hydrogen-Bond Jumps Rather than Collective Coupling to Ion Clusters Article de journal Guillaume Stirnemann; Pavel Jungwirth; D Laage Proceedings of the National Academy of Sciences of the United States of America, 115 (22), p. E4953-E4954, 2018, ISSN: 0027-8424, (WOS:000433283700001). @article{Stirnemann:2018, title = {Water Dynamics in Concentrated Electrolytes: Local Ion Effect on Hydrogen-Bond Jumps Rather than Collective Coupling to Ion Clusters}, author = {Guillaume Stirnemann and Pavel Jungwirth and D Laage}, doi = {10.1073/pnas.1803988115}, issn = {0027-8424}, year = {2018}, date = {2018-05-01}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {115}, number = {22}, pages = {E4953-E4954}, note = {WOS:000433283700001}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Ion-Induced Long-Range Orientational Correlations in Water: Strong or Weak, Physiologically Relevant or Unimportant, and Unique to Water or Not? Article de journal P Jungwirth; D Laage Journal of Physical Chemistry Letters, 9 (8), p. 2056–2057, 2018. @article{Jungwirth:2018, title = {Ion-Induced Long-Range Orientational Correlations in Water: Strong or Weak, Physiologically Relevant or Unimportant, and Unique to Water or Not?}, author = {P Jungwirth and D Laage}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045736133&doi=10.1021%2facs.jpclett.8b01027&partnerID=40&md5=7b136d1325f85fcca534af625c206111}, doi = {10.1021/acs.jpclett.8b01027}, year = {2018}, date = {2018-01-01}, journal = {Journal of Physical Chemistry Letters}, volume = {9}, number = {8}, pages = {2056--2057}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Metalation of Porphyrins by Lanthanide Atoms at Interfaces: Direct Observation and Stimulation of Cerium Coordination to 2H-TPP/Ag(111) Article de journal F Bischoff; K Seufert; W Auwärter; A P Seitsonen; D Heim; J V Barth Journal of Physical Chemistry C, 122 (9), p. 5083–5092, 2018. @article{Bischoff:2018, title = {Metalation of Porphyrins by Lanthanide Atoms at Interfaces: Direct Observation and Stimulation of Cerium Coordination to 2H-TPP/Ag(111)}, author = {F Bischoff and K Seufert and W Auw\"{a}rter and A P Seitsonen and D Heim and J V Barth}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042264710&doi=10.1021%2facs.jpcc.7b10363&partnerID=40&md5=0c6e1e73b88b78f19852bd70a6a232f1}, doi = {10.1021/acs.jpcc.7b10363}, year = {2018}, date = {2018-01-01}, journal = {Journal of Physical Chemistry C}, volume = {122}, number = {9}, pages = {5083--5092}, abstract = {Although on-surface metalation protocols of tetrapyrroles with 3d metals are well established, reports on the formation of lanthanide tetrapyrrole complexes are scarce. Here, we address the synthesis of lanthanide-tetrapyrrole units in detail, refining earlier findings. Specifically, the formation of cerium tetraphenylporphyrin (Ce-TPP) was induced on Ag(111) either by thermal annealing or by a manipulation procedure using a scanning tunneling microscope (STM) tip. While the self-assembled TPP arrays are not altered upon Ce metalation, our STM observations show distinct modifications of submolecular features reflecting a multistep reaction pathway. The metalation proceeds from an initial configuration with a 2H-TPP molecule sitting atop a Ce atom via an intermediate state, where the macrocycle is partially deprotonated, to metalated Ce-TPP. The hitherto elusive 1H species - hypothesized in several 3d metalation studies - is visualized directly. Our study provides novel insights into the on-surface synthesis of tetrapyrroles and lanthanide-based nanosystems. © 2018 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Although on-surface metalation protocols of tetrapyrroles with 3d metals are well established, reports on the formation of lanthanide tetrapyrrole complexes are scarce. Here, we address the synthesis of lanthanide-tetrapyrrole units in detail, refining earlier findings. Specifically, the formation of cerium tetraphenylporphyrin (Ce-TPP) was induced on Ag(111) either by thermal annealing or by a manipulation procedure using a scanning tunneling microscope (STM) tip. While the self-assembled TPP arrays are not altered upon Ce metalation, our STM observations show distinct modifications of submolecular features reflecting a multistep reaction pathway. The metalation proceeds from an initial configuration with a 2H-TPP molecule sitting atop a Ce atom via an intermediate state, where the macrocycle is partially deprotonated, to metalated Ce-TPP. The hitherto elusive 1H species - hypothesized in several 3d metalation studies - is visualized directly. Our study provides novel insights into the on-surface synthesis of tetrapyrroles and lanthanide-based nanosystems. © 2018 American Chemical Society. |
Elemental Identification by Combining Atomic Force Microscopy and Kelvin Probe Force Microscopy Article de journal F Schulz; J Ritala; O Krejčí; A P Seitsonen; A S Foster; P Liljeroth ACS Nano, 12 (6), p. 5274–5283, 2018. @article{Schulz:2018, title = {Elemental Identification by Combining Atomic Force Microscopy and Kelvin Probe Force Microscopy}, author = {F Schulz and J Ritala and O Krej\v{c}\'{i} and A P Seitsonen and A S Foster and P Liljeroth}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047773715&doi=10.1021%2facsnano.7b08997&partnerID=40&md5=0f4b1ad25f886b3a2a8f9b440c657685}, doi = {10.1021/acsnano.7b08997}, year = {2018}, date = {2018-01-01}, journal = {ACS Nano}, volume = {12}, number = {6}, pages = {5274--5283}, abstract = {There are currently no experimental techniques that combine atomic-resolution imaging with elemental sensitivity and chemical fingerprinting on single molecules. The advent of using molecular-modified tips in noncontact atomic force microscopy (nc-AFM) has made it possible to image (planar) molecules with atomic resolution. However, the mechanisms responsible for elemental contrast with passivated tips are not fully understood. Here, we investigate elemental contrast by carrying out both nc-AFM and Kelvin probe force microscopy (KPFM) experiments on epitaxial monolayer hexagonal boron nitride (hBN) on Ir(111). The hBN overlayer is inert, and the in-plane bonds connecting nearest-neighbor boron and nitrogen atoms possess strong covalent character and a bond length of only ∼1.45 r{A}. Nevertheless, constant-height maps of both the frequency shift Δf and the local contact potential difference exhibit striking sublattice asymmetry. We match the different atomic sites with the observed contrast by comparison with nc-AFM image simulations based on the density functional theory optimized hBN/Ir(111) geometry, which yields detailed information on the origin of the atomic-scale contrast. © 2018 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } There are currently no experimental techniques that combine atomic-resolution imaging with elemental sensitivity and chemical fingerprinting on single molecules. The advent of using molecular-modified tips in noncontact atomic force microscopy (nc-AFM) has made it possible to image (planar) molecules with atomic resolution. However, the mechanisms responsible for elemental contrast with passivated tips are not fully understood. Here, we investigate elemental contrast by carrying out both nc-AFM and Kelvin probe force microscopy (KPFM) experiments on epitaxial monolayer hexagonal boron nitride (hBN) on Ir(111). The hBN overlayer is inert, and the in-plane bonds connecting nearest-neighbor boron and nitrogen atoms possess strong covalent character and a bond length of only ∼1.45 Å. Nevertheless, constant-height maps of both the frequency shift Δf and the local contact potential difference exhibit striking sublattice asymmetry. We match the different atomic sites with the observed contrast by comparison with nc-AFM image simulations based on the density functional theory optimized hBN/Ir(111) geometry, which yields detailed information on the origin of the atomic-scale contrast. © 2018 American Chemical Society. |
Epitaxial Synthesis of Blue Phosphorene Article de journal W Zhang; H Enriquez; Y Tong; A Bendounan; A Kara; A P Seitsonen; A J Mayne; G Dujardin; H Oughaddou Small, 14 (51), 2018. @article{Zhang:2018b, title = {Epitaxial Synthesis of Blue Phosphorene}, author = {W Zhang and H Enriquez and Y Tong and A Bendounan and A Kara and A P Seitsonen and A J Mayne and G Dujardin and H Oughaddou}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055703645&doi=10.1002%2fsmll.201804066&partnerID=40&md5=8f4837161dc29a33bfa5b4c3a35fab0d}, doi = {10.1002/smll.201804066}, year = {2018}, date = {2018-01-01}, journal = {Small}, volume = {14}, number = {51}, abstract = {Phosphorene is a new 2D material composed of a single or few atomic layers of black phosphorus. Phosphorene has both an intrinsic tunable direct bandgap and high carrier mobility values, which make it suitable for a large variety of optical and electronic devices. However, the synthesis of single-layer phosphorene is a major challenge. The standard procedure to obtain phosphorene is by exfoliation. More recently, the epitaxial growth of single-layer phosphorene on Au(111) was investigated by molecular beam epitaxy and the obtained structure described as a blue phosphorene sheet. In the present study, large areas of high-quality monolayer phosphorene, with a bandgap value equal to at least 0.8 eV, are synthesized on Au(111). The experimental investigations, coupled with density functional theory calculations, give evidence of two distinct phases of blue phosphorene on Au(111), instead of one as previously reported, and their atomic structures are determined. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim}, keywords = {}, pubstate = {published}, tppubtype = {article} } Phosphorene is a new 2D material composed of a single or few atomic layers of black phosphorus. Phosphorene has both an intrinsic tunable direct bandgap and high carrier mobility values, which make it suitable for a large variety of optical and electronic devices. However, the synthesis of single-layer phosphorene is a major challenge. The standard procedure to obtain phosphorene is by exfoliation. More recently, the epitaxial growth of single-layer phosphorene on Au(111) was investigated by molecular beam epitaxy and the obtained structure described as a blue phosphorene sheet. In the present study, large areas of high-quality monolayer phosphorene, with a bandgap value equal to at least 0.8 eV, are synthesized on Au(111). The experimental investigations, coupled with density functional theory calculations, give evidence of two distinct phases of blue phosphorene on Au(111), instead of one as previously reported, and their atomic structures are determined. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim |
Electrostatic Interaction across a Single-Layer Carbon Shell Article de journal R Stania; A P Seitsonen; D Kunhardt; B Büchner; A A Popov; M Muntwiler; T Greber Journal of Physical Chemistry Letters, 9 (13), p. 3586–3590, 2018. @article{Stania:2018, title = {Electrostatic Interaction across a Single-Layer Carbon Shell}, author = {R Stania and A P Seitsonen and D Kunhardt and B B\"{u}chner and A A Popov and M Muntwiler and T Greber}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048726599&doi=10.1021%2facs.jpclett.8b01326&partnerID=40&md5=cedea2bb7be44b0fd895ba245c6ef72e}, doi = {10.1021/acs.jpclett.8b01326}, year = {2018}, date = {2018-01-01}, journal = {Journal of Physical Chemistry Letters}, volume = {9}, number = {13}, pages = {3586--3590}, abstract = {Ions inside of fullerene molecules are model systems for the study of the electrostatic interaction across a single layer of carbon. For TbSc2N@C80 on h-BN/Ni(111), we observe with high-resolution X-ray photoelectron spectroscopy a splitting of the C 1s core level. The data may be explained quantitatively with density functional theory. The correlation of the C 1s eigenvalues and the Coulomb potential of the inside ions at the corresponding carbon sites indicates incomplete screening of the electric field due to the endohedral ions. The screening comprises anisotropic charge transfer to the carbon atoms and their polarization. This behavior is essential for the ordering of endohedral single-molecule magnets and is expected to occur in any single-layer material. Copyright © 2018 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Ions inside of fullerene molecules are model systems for the study of the electrostatic interaction across a single layer of carbon. For TbSc2N@C80 on h-BN/Ni(111), we observe with high-resolution X-ray photoelectron spectroscopy a splitting of the C 1s core level. The data may be explained quantitatively with density functional theory. The correlation of the C 1s eigenvalues and the Coulomb potential of the inside ions at the corresponding carbon sites indicates incomplete screening of the electric field due to the endohedral ions. The screening comprises anisotropic charge transfer to the carbon atoms and their polarization. This behavior is essential for the ordering of endohedral single-molecule magnets and is expected to occur in any single-layer material. Copyright © 2018 American Chemical Society. |
Complex supramolecular interfacial tessellation through convergent multi-step reaction of a dissymmetric simple organic precursor Article de journal Y -Q Zhang; M Paszkiewicz; P Du; L Zhang; T Lin; Z Chen; S Klyatskaya; M Ruben; A P Seitsonen; J V Barth; F Klappenberger Nature Chemistry, 10 (3), p. 296–304, 2018. @article{Zhang:2018a, title = {Complex supramolecular interfacial tessellation through convergent multi-step reaction of a dissymmetric simple organic precursor}, author = {Y -Q Zhang and M Paszkiewicz and P Du and L Zhang and T Lin and Z Chen and S Klyatskaya and M Ruben and A P Seitsonen and J V Barth and F Klappenberger}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042210816&doi=10.1038%2fnchem.2924&partnerID=40&md5=9a186e74d46e676b7000d6bb842f090b}, doi = {10.1038/nchem.2924}, year = {2018}, date = {2018-01-01}, journal = {Nature Chemistry}, volume = {10}, number = {3}, pages = {296--304}, abstract = {Interfacial supramolecular self-assembly represents a powerful tool for constructing regular and quasicrystalline materials. In particular, complex two-dimensional molecular tessellations, such as semi-regular Archimedean tilings with regular polygons, promise unique properties related to their nontrivial structures. However, their formation is challenging, because current methods are largely limited to the direct assembly of precursors, that is, where structure formation relies on molecular interactions without using chemical transformations. Here, we have chosen ethynyl-iodophenanthrene (which features dissymmetry in both geometry and reactivity) as a single starting precursor to generate the rare semi-regular (3.4.6.4) Archimedean tiling with long-range order on an atomically flat substrate through a multi-step reaction. Intriguingly, the individual chemical transformations converge to form a symmetric alkynyl-Ag-alkynyl complex as the new tecton in high yields. Using a combination of microscopy and X-ray spectroscopy tools, as well as computational modelling, we show that in situ generated catalytic Ag complexes mediate the tecton conversion. © 2018 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Interfacial supramolecular self-assembly represents a powerful tool for constructing regular and quasicrystalline materials. In particular, complex two-dimensional molecular tessellations, such as semi-regular Archimedean tilings with regular polygons, promise unique properties related to their nontrivial structures. However, their formation is challenging, because current methods are largely limited to the direct assembly of precursors, that is, where structure formation relies on molecular interactions without using chemical transformations. Here, we have chosen ethynyl-iodophenanthrene (which features dissymmetry in both geometry and reactivity) as a single starting precursor to generate the rare semi-regular (3.4.6.4) Archimedean tiling with long-range order on an atomically flat substrate through a multi-step reaction. Intriguingly, the individual chemical transformations converge to form a symmetric alkynyl-Ag-alkynyl complex as the new tecton in high yields. Using a combination of microscopy and X-ray spectroscopy tools, as well as computational modelling, we show that in situ generated catalytic Ag complexes mediate the tecton conversion. © 2018 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. |
An electron acceptor molecule in a nanomesh: F4TCNQ on h-BN/Rh(111) Article de journal H Cun; A P Seitsonen; S Roth; S Decurtins; S -X Liu; J Osterwalder; T Greber Surface Science, 678 , p. 183–188, 2018. @article{Cun:2018, title = {An electron acceptor molecule in a nanomesh: F4TCNQ on h-BN/Rh(111)}, author = {H Cun and A P Seitsonen and S Roth and S Decurtins and S -X Liu and J Osterwalder and T Greber}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047523394&doi=10.1016%2fj.susc.2018.04.026&partnerID=40&md5=b11163122532af15be7bbc27e1eb79a7}, doi = {10.1016/j.susc.2018.04.026}, year = {2018}, date = {2018-01-01}, journal = {Surface Science}, volume = {678}, pages = {183--188}, abstract = {The adsorption of molecules on surfaces affects the surface dipole and thus changes in the work function may be expected. The effect in change of work function is particularly strong if charge between substrate and adsorbate is involved. Here we report the deposition of a strong electron acceptor molecule, tetrafluorotetracyanoquinodimethane C12F4N4 (F4TCNQ) on a monolayer of hexagonal boron nitride nanomesh (h-BN on Rh(111)). The work function of the F4TCNQ/h-BN/Rh system increases upon increasing molecular coverage. The magnitude of the effect indicates electron transfer from the substrate to the F4TCNQ molecules. Density functional theory calculations confirm the work function shift and predict doubly-charged F4TCNQ2− in the nanomesh pores, where the h-BN is closest to the Rh substrate, and to have the largest binding energy there. The preferred adsorption in the pores is conjectured from a series of ultraviolet photoelectron spectroscopy data, where the σ bands in the pores are first attenuated. Scanning tunneling microscopy measurements indicate that F4TCNQ molecules on the nanomesh are mobile at room temperature, as “hopping” between neighboring pores is observed. © 2018 Elsevier B.V.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The adsorption of molecules on surfaces affects the surface dipole and thus changes in the work function may be expected. The effect in change of work function is particularly strong if charge between substrate and adsorbate is involved. Here we report the deposition of a strong electron acceptor molecule, tetrafluorotetracyanoquinodimethane C12F4N4 (F4TCNQ) on a monolayer of hexagonal boron nitride nanomesh (h-BN on Rh(111)). The work function of the F4TCNQ/h-BN/Rh system increases upon increasing molecular coverage. The magnitude of the effect indicates electron transfer from the substrate to the F4TCNQ molecules. Density functional theory calculations confirm the work function shift and predict doubly-charged F4TCNQ2− in the nanomesh pores, where the h-BN is closest to the Rh substrate, and to have the largest binding energy there. The preferred adsorption in the pores is conjectured from a series of ultraviolet photoelectron spectroscopy data, where the σ bands in the pores are first attenuated. Scanning tunneling microscopy measurements indicate that F4TCNQ molecules on the nanomesh are mobile at room temperature, as “hopping” between neighboring pores is observed. © 2018 Elsevier B.V. |
XXIXth IUPAP Conference on Computational Physics (CCP2017) Article de journal R Spezia; A M Saitta; R Vuilleumier 1136 (1), 2018. @article{Spezia:2018, title = {XXIXth IUPAP Conference on Computational Physics (CCP2017)}, author = {R Spezia and A M Saitta and R Vuilleumier}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059360437&doi=10.1088%2f1742-6596%2f1136%2f1%2f011001&partnerID=40&md5=82975b1c03fbf48b7394d70a495b8b47}, doi = {10.1088/1742-6596/1136/1/011001}, year = {2018}, date = {2018-01-01}, volume = {1136}, number = {1}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Structure and Dynamics of Water Confined in Imogolite Nanotubes Article de journal L Scalfi; G Fraux; A Boutin; F -X Coudert Langmuir, 34 (23), p. 6748–6756, 2018. @article{Scalfi:2018, title = {Structure and Dynamics of Water Confined in Imogolite Nanotubes}, author = {L Scalfi and G Fraux and A Boutin and F -X Coudert}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047523465&doi=10.1021%2facs.langmuir.8b01115&partnerID=40&md5=9455a53f6fa2fb1284823137a632d2e5}, doi = {10.1021/acs.langmuir.8b01115}, year = {2018}, date = {2018-01-01}, journal = {Langmuir}, volume = {34}, number = {23}, pages = {6748--6756}, abstract = {We have studied the properties of water adsorbed inside nanotubes of hydrophilic imogolite, an aluminum silicate clay mineral, by means of molecular simulations. We used a classical force field to describe the water and the flexible imogolite nanotube and validated it against the data obtained from first-principles molecular dynamics. With it, we observe a strong structuration of the water confined in the nanotube, with specific adsorption sites and a distribution of hydrogen bond patterns. The combination of number of adsorption sites, their geometry, and the preferential tetrahedral hydrogen bonding pattern of water leads to frustration and disorder. We further characterize the dynamics of the water, as well as the hydrogen bonds formed between water molecules and the nanotube, which is found to be more than 1 order of magnitude longer than water-water hydrogen bonds. Copyright © 2018 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We have studied the properties of water adsorbed inside nanotubes of hydrophilic imogolite, an aluminum silicate clay mineral, by means of molecular simulations. We used a classical force field to describe the water and the flexible imogolite nanotube and validated it against the data obtained from first-principles molecular dynamics. With it, we observe a strong structuration of the water confined in the nanotube, with specific adsorption sites and a distribution of hydrogen bond patterns. The combination of number of adsorption sites, their geometry, and the preferential tetrahedral hydrogen bonding pattern of water leads to frustration and disorder. We further characterize the dynamics of the water, as well as the hydrogen bonds formed between water molecules and the nanotube, which is found to be more than 1 order of magnitude longer than water-water hydrogen bonds. Copyright © 2018 American Chemical Society. |
Structure and Dynamics of Solvated Polymers near a Silica Surface: On the Different Roles Played by Solvent Article de journal E Perrin; M Schoen; F -X Coudert; A Boutin Journal of Physical Chemistry B, 122 (16), p. 4573–4582, 2018. @article{Perrin:2018, title = {Structure and Dynamics of Solvated Polymers near a Silica Surface: On the Different Roles Played by Solvent}, author = {E Perrin and M Schoen and F -X Coudert and A Boutin}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85046023808&doi=10.1021%2facs.jpcb.7b11753&partnerID=40&md5=454946e682d8338778f6c89c84b3f873}, doi = {10.1021/acs.jpcb.7b11753}, year = {2018}, date = {2018-01-01}, journal = {Journal of Physical Chemistry B}, volume = {122}, number = {16}, pages = {4573--4582}, abstract = {Whereas it is experimentally known that the inclusion of nanoparticles in hydrogels can lead to a mechanical reinforcement, a detailed molecular understanding of the adhesion mechanism is still lacking. Here we use coarse-grained molecular dynamics simulations to investigate the nature of the interface between silica surfaces and solvated polymers. We show how differences in the nature of the polymer and the polymer-solvent interactions can lead to drastically different behavior of the polymer-surface adhesion. Comparing explicit and implicit solvent models, we conclude that this effect cannot be fully described in an implicit solvent. We highlight the crucial role of polymer solvation for the adsorption of the polymer chain on the silica surface, the significant dynamics of polymer chains on the surface, and details of the modifications in the structure solvated polymer close to the interface. © 2018 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Whereas it is experimentally known that the inclusion of nanoparticles in hydrogels can lead to a mechanical reinforcement, a detailed molecular understanding of the adhesion mechanism is still lacking. Here we use coarse-grained molecular dynamics simulations to investigate the nature of the interface between silica surfaces and solvated polymers. We show how differences in the nature of the polymer and the polymer-solvent interactions can lead to drastically different behavior of the polymer-surface adhesion. Comparing explicit and implicit solvent models, we conclude that this effect cannot be fully described in an implicit solvent. We highlight the crucial role of polymer solvation for the adsorption of the polymer chain on the silica surface, the significant dynamics of polymer chains on the surface, and details of the modifications in the structure solvated polymer close to the interface. © 2018 American Chemical Society. |
On the use of the IAST method for gas separation studies in porous materials with gate-opening behavior Article de journal G Fraux; A Boutin; A H Fuchs; F -X Coudert Adsorption, 24 (3), p. 233–241, 2018. @article{Fraux:2018, title = {On the use of the IAST method for gas separation studies in porous materials with gate-opening behavior}, author = {G Fraux and A Boutin and A H Fuchs and F -X Coudert}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044316029&doi=10.1007%2fs10450-018-9942-5&partnerID=40&md5=094abd3fbb204080fc964f1f0781ba71}, doi = {10.1007/s10450-018-9942-5}, year = {2018}, date = {2018-01-01}, journal = {Adsorption}, volume = {24}, number = {3}, pages = {233--241}, abstract = {Abstract: Highly flexible nanoporous materials, exhibiting for instance gate opening or breathing behavior, are often presented as candidates for separation processes due to their supposed high adsorption selectivity. But this view, based on “classical” considerations of rigid materials and the use of the Ideal Adsorbed Solution Theory (IAST), does not necessarily hold in the presence of framework deformations. Here, we revisit some results from the published literature and show how proper inclusion of framework flexibility in the osmotic thermodynamic ensemble drastically changes the conclusions, in contrast to what intuition and standard IAST would yield. In all cases, the IAST method does not reproduce the gate-opening behavior in the adsorption of mixtures, and may overestimates the selectivity by up to two orders of magnitude. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Abstract: Highly flexible nanoporous materials, exhibiting for instance gate opening or breathing behavior, are often presented as candidates for separation processes due to their supposed high adsorption selectivity. But this view, based on “classical” considerations of rigid materials and the use of the Ideal Adsorbed Solution Theory (IAST), does not necessarily hold in the presence of framework deformations. Here, we revisit some results from the published literature and show how proper inclusion of framework flexibility in the osmotic thermodynamic ensemble drastically changes the conclusions, in contrast to what intuition and standard IAST would yield. In all cases, the IAST method does not reproduce the gate-opening behavior in the adsorption of mixtures, and may overestimates the selectivity by up to two orders of magnitude. © 2018, Springer Science+Business Media, LLC, part of Springer Nature. |
Classical Polarizable Force Field to Study Hydrated Charged Clays and Zeolites Article de journal S Tesson; W Louisfrema; M Salanne; A Boutin; E Ferrage; B Rotenberg; V Marry Journal of Physical Chemistry C, 122 (43), p. 24690–24704, 2018. @article{Tesson:2018, title = {Classical Polarizable Force Field to Study Hydrated Charged Clays and Zeolites}, author = {S Tesson and W Louisfrema and M Salanne and A Boutin and E Ferrage and B Rotenberg and V Marry}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056108305&doi=10.1021%2facs.jpcc.8b06230&partnerID=40&md5=7039754c45487a2d939680ec685cf6d0}, doi = {10.1021/acs.jpcc.8b06230}, year = {2018}, date = {2018-01-01}, journal = {Journal of Physical Chemistry C}, volume = {122}, number = {43}, pages = {24690--24704}, abstract = {Following our previous works on dry clays, we extend the classical polarizable ion model (PIM) to hydrated dioctahedral clays by considering Na-, Cs-, Ca-, and Sr-montmorillonites in the mono- and bihydrated states. The parameters of the force field are determined by optimizing the atomic forces and dipoles on density functional theory calculations. The simulation results are compared with results obtained with CLAYFF force field and validated in comparison with the experiment. The X-ray diffraction patterns calculated from classical molecular dynamics simulations performed with the PIM force field are in very good agreement with experiments. We also demonstrate the transferability of PIM force field to other aluminosilicates: here, a faujasite-type zeolite compensated with Na+ with a significant improvement in cation locations compared to nonpolarizable force fields. © 2018 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Following our previous works on dry clays, we extend the classical polarizable ion model (PIM) to hydrated dioctahedral clays by considering Na-, Cs-, Ca-, and Sr-montmorillonites in the mono- and bihydrated states. The parameters of the force field are determined by optimizing the atomic forces and dipoles on density functional theory calculations. The simulation results are compared with results obtained with CLAYFF force field and validated in comparison with the experiment. The X-ray diffraction patterns calculated from classical molecular dynamics simulations performed with the PIM force field are in very good agreement with experiments. We also demonstrate the transferability of PIM force field to other aluminosilicates: here, a faujasite-type zeolite compensated with Na+ with a significant improvement in cation locations compared to nonpolarizable force fields. © 2018 American Chemical Society. |
Moment propagation method for the dynamics of charged adsorbing/desorbing species at solid-liquid interfaces Article de journal A Asta; M Levesque; B Rotenberg Molecular Physics, 116 (21-22), p. 2965–2976, 2018. @article{Asta:2018, title = {Moment propagation method for the dynamics of charged adsorbing/desorbing species at solid-liquid interfaces}, author = {A Asta and M Levesque and B Rotenberg}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045739593&doi=10.1080%2f00268976.2018.1461944&partnerID=40&md5=165d10ae23edb56bd618e9fd667aab06}, doi = {10.1080/00268976.2018.1461944}, year = {2018}, date = {2018-01-01}, journal = {Molecular Physics}, volume = {116}, number = {21-22}, pages = {2965--2976}, abstract = {We extend the moment propagation method to capture the combined effects of adsorption/desorption of charged tracers, their migration under local and applied electric fields, as well as their advection by the local velocity of the fluid. This is achieved by combining previous developments for the separate description of these phenomena, in particular taking advantage of the Lattice Boltzmann Electrokinetics method to capture electrokinetic effects in the underlying fluid. We validate the method on the case of dispersion by an electro-osmotic flow in a slit-pore with charged walls and counter-ions in the absence of added salt. We compute the velocity auto-correlation function of charged and neutral tracers, from which we extract their average mobility and dispersion coefficient. Analytical results for the former allow to validate the algorithm, while the latter illustrates an example of property which can be provided by the moment propagation method when no analytical results are available. For both properties, we discuss the combined effects of the surface charge, of the tracer valency and of the adsorption/desorption rates. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We extend the moment propagation method to capture the combined effects of adsorption/desorption of charged tracers, their migration under local and applied electric fields, as well as their advection by the local velocity of the fluid. This is achieved by combining previous developments for the separate description of these phenomena, in particular taking advantage of the Lattice Boltzmann Electrokinetics method to capture electrokinetic effects in the underlying fluid. We validate the method on the case of dispersion by an electro-osmotic flow in a slit-pore with charged walls and counter-ions in the absence of added salt. We compute the velocity auto-correlation function of charged and neutral tracers, from which we extract their average mobility and dispersion coefficient. Analytical results for the former allow to validate the algorithm, while the latter illustrates an example of property which can be provided by the moment propagation method when no analytical results are available. For both properties, we discuss the combined effects of the surface charge, of the tracer valency and of the adsorption/desorption rates. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group. |
What Does Second-Harmonic Scattering Measure in Diluted Electrolytes? Article de journal D Borgis; L Belloni; M Levesque Journal of Physical Chemistry Letters, 9 (13), p. 3698–3702, 2018. @article{Borgis:2018, title = {What Does Second-Harmonic Scattering Measure in Diluted Electrolytes?}, author = {D Borgis and L Belloni and M Levesque}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048728676&doi=10.1021%2facs.jpclett.8b01690&partnerID=40&md5=9c8feda9b9b18f773d4a2bb83982ca49}, doi = {10.1021/acs.jpclett.8b01690}, year = {2018}, date = {2018-01-01}, journal = {Journal of Physical Chemistry Letters}, volume = {9}, number = {13}, pages = {3698--3702}, abstract = {We derive a theoretical expression of the second harmonic scattering signal in diluted electrolytes compared with bulk water. We show that the enhancement of the signal with respect to pure water observed recently for electrolytes at very low dilution in the micromolar range is a mere manifestation of the Debye screening that makes the infinite-range dipole-dipole solvent correlations in 1/r3 disappear as soon as the ionic concentration becomes finite. In q space, this translates into a correlation function having a well known singular behavior around q = 0, which drives the observed ionic effects. We find that the signal is independent of the ion-induced long-range behavior of the function «cos ψ(r)» that has been recently discussed. We find also that the enhancement depends on the experimental geometry and occurs only for in-plane polarization detection, as observed experimentally. On the contrary, the measured isotope effect between light and heavy water cannot be fully explained. © 2018 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We derive a theoretical expression of the second harmonic scattering signal in diluted electrolytes compared with bulk water. We show that the enhancement of the signal with respect to pure water observed recently for electrolytes at very low dilution in the micromolar range is a mere manifestation of the Debye screening that makes the infinite-range dipole-dipole solvent correlations in 1/r3 disappear as soon as the ionic concentration becomes finite. In q space, this translates into a correlation function having a well known singular behavior around q = 0, which drives the observed ionic effects. We find that the signal is independent of the ion-induced long-range behavior of the function «cos ψ(r)» that has been recently discussed. We find also that the enhancement depends on the experimental geometry and occurs only for in-plane polarization detection, as observed experimentally. On the contrary, the measured isotope effect between light and heavy water cannot be fully explained. © 2018 American Chemical Society. |
Screened Coulombic Orientational Correlations in Dilute Aqueous Electrolytes Article de journal L Belloni; D Borgis; M Levesque Journal of Physical Chemistry Letters, 9 (8), p. 1985–1989, 2018. @article{Belloni:2018, title = {Screened Coulombic Orientational Correlations in Dilute Aqueous Electrolytes}, author = {L Belloni and D Borgis and M Levesque}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045752793&doi=10.1021%2facs.jpclett.8b00606&partnerID=40&md5=7f6e4b2432b0a2f8f179b4ceacee7e4b}, doi = {10.1021/acs.jpclett.8b00606}, year = {2018}, date = {2018-01-01}, journal = {Journal of Physical Chemistry Letters}, volume = {9}, number = {8}, pages = {1985--1989}, abstract = {The ion-induced long-range orientational order between water molecules recently observed in second harmonic scattering experiments and illustrated with large scale molecular dynamics simulations is quantitatively explained using the Ornstein-Zernike integral equation approach of liquid physics. This general effect, not specific to hydrogen-bonding solvents, is controlled by electroneutrality conditions, dipolar interactions, and dielectric+ionic screening. As expected, all numerical theories recover the well-known analytical expressions established 40 years ago. © 2018 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The ion-induced long-range orientational order between water molecules recently observed in second harmonic scattering experiments and illustrated with large scale molecular dynamics simulations is quantitatively explained using the Ornstein-Zernike integral equation approach of liquid physics. This general effect, not specific to hydrogen-bonding solvents, is controlled by electroneutrality conditions, dipolar interactions, and dielectric+ionic screening. As expected, all numerical theories recover the well-known analytical expressions established 40 years ago. © 2018 American Chemical Society. |
Roles of Hydration for Inducing Decomposition of 2-Deoxy-d-ribose by Ionization of Oxygen K-Shell Electrons Article de journal K Fujii; Y Izumi; A Narita; K K Ghose; P López-Tarifa; A Touati; R Spezia; R Vuilleumier; M -P Gaigeot; M -F Politis; M -A H Du Penhoat; A Yokoya Radiation Research, 189 (3), p. 264–272, 2018. @article{Fujii:2018, title = {Roles of Hydration for Inducing Decomposition of 2-Deoxy-d-ribose by Ionization of Oxygen K-Shell Electrons}, author = {K Fujii and Y Izumi and A Narita and K K Ghose and P L\'{o}pez-Tarifa and A Touati and R Spezia and R Vuilleumier and M -P Gaigeot and M -F Politis and M -A H Du Penhoat and A Yokoya}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042916011&doi=10.1667%2fRR14225.1&partnerID=40&md5=d10f35f67ddcf004a95dfc3665db57e1}, doi = {10.1667/RR14225.1}, year = {2018}, date = {2018-01-01}, journal = {Radiation Research}, volume = {189}, number = {3}, pages = {264--272}, abstract = {To experimentally investigate the role of hydration in the initial process of the decomposition of 2-deoxy-d-ribose (dR), which is a major component of the DNA backbone, we used mass spectrometry to monitor the ions desorbing from hydrated dR films exposed to monochromatic soft X rays (560 eV). The X-ray photons preferentially ionize the K-shell electrons of the oxygen atoms in DNA. Hydrated dR samples were prepared under vacuum by exposing a cooled (textasciitilde150 K) dR film deposited on a Si substrate to water vapor. Using a quadrupole mass spectrometer, we observed the desorption of ions such as H+, CHx +, C2Hx +, CHxO+, C3Hx + and C2HxO+ (x = 1, 2, 3 and 4). In addition, the desorption of H2O+ or H3O+ was observed in the mass spectra of hydrated dR films. Except for H+, the yields of these ions decreased when one layer of water molecules was deposited onto the film. These ions are produced by C-C or C-O bond scission. This result suggests that the water molecules act as a quencher, suppressing Coulomb repulsion and thus the extensive molecular decomposition of dR. Ab initio molecular dynamics simulations were performed to rationalize the fragments observed in the experiments. The results of the dynamical process of a hydrated dR molecule after oxygen K-ionization revealed elongation of a C-O bond of dR and the O-H bonds of both dR and water molecules prior to the Auger process, resulting in the ejection of H+ ions. These results strongly suggest that the very early process contributes to reducing the dR fragmentation, producing the H3O+ and H+ detected from the hydrated dR films. These desorbed ions may be involved in the induction of other types of damage, such as oxidatively generated base lesions, concomitantly produced with a strand break when produced in DNA. © 2018 by Radiation Research Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } To experimentally investigate the role of hydration in the initial process of the decomposition of 2-deoxy-d-ribose (dR), which is a major component of the DNA backbone, we used mass spectrometry to monitor the ions desorbing from hydrated dR films exposed to monochromatic soft X rays (560 eV). The X-ray photons preferentially ionize the K-shell electrons of the oxygen atoms in DNA. Hydrated dR samples were prepared under vacuum by exposing a cooled (textasciitilde150 K) dR film deposited on a Si substrate to water vapor. Using a quadrupole mass spectrometer, we observed the desorption of ions such as H+, CHx +, C2Hx +, CHxO+, C3Hx + and C2HxO+ (x = 1, 2, 3 and 4). In addition, the desorption of H2O+ or H3O+ was observed in the mass spectra of hydrated dR films. Except for H+, the yields of these ions decreased when one layer of water molecules was deposited onto the film. These ions are produced by C-C or C-O bond scission. This result suggests that the water molecules act as a quencher, suppressing Coulomb repulsion and thus the extensive molecular decomposition of dR. Ab initio molecular dynamics simulations were performed to rationalize the fragments observed in the experiments. The results of the dynamical process of a hydrated dR molecule after oxygen K-ionization revealed elongation of a C-O bond of dR and the O-H bonds of both dR and water molecules prior to the Auger process, resulting in the ejection of H+ ions. These results strongly suggest that the very early process contributes to reducing the dR fragmentation, producing the H3O+ and H+ detected from the hydrated dR films. These desorbed ions may be involved in the induction of other types of damage, such as oxidatively generated base lesions, concomitantly produced with a strand break when produced in DNA. © 2018 by Radiation Research Society. |
Proton Collision on Deoxyribose Originating from Doubly Ionized Water Molecule Dissociation Article de journal M -A Hervé Du Penhoat; N R Moraga; M -P Gaigeot; R Vuilleumier; I Tavernelli; M -F Politis Journal of Physical Chemistry A, 122 (24), p. 5311–5320, 2018. @article{HerveDuPenhoat:2018, title = {Proton Collision on Deoxyribose Originating from Doubly Ionized Water Molecule Dissociation}, author = {M -A Herv\'{e} Du Penhoat and N R Moraga and M -P Gaigeot and R Vuilleumier and I Tavernelli and M -F Politis}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048026702&doi=10.1021%2facs.jpca.8b04787&partnerID=40&md5=8f237ed86c71a0b5043c76457bf360aa}, doi = {10.1021/acs.jpca.8b04787}, year = {2018}, date = {2018-01-01}, journal = {Journal of Physical Chemistry A}, volume = {122}, number = {24}, pages = {5311--5320}, abstract = {In this work, we studied the fragmentation dynamics of 2-deoxy-d-ribose (DR) in solution that arises from the double ionization of a water molecule in its primary hydration shell. This process was modeled in the framework of ab initio molecular dynamics. The charge unbalanced in the solvent molecules produces a Coulomb explosion with the consequent release of protons with kinetic energy in the few electronvolts range, which collide with the surrounding molecules in solution inducing further chemical reactions. In particular, we observe proton collisions with the solute molecule DR, which leads to a complete ring opening. In DNA, damage to the DR moiety may lead to DNA strand breaking. This mechanism can be understood as one of the possible steps in the radiation-induced fragmentation of DNA chains. Copyright © 2018 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In this work, we studied the fragmentation dynamics of 2-deoxy-d-ribose (DR) in solution that arises from the double ionization of a water molecule in its primary hydration shell. This process was modeled in the framework of ab initio molecular dynamics. The charge unbalanced in the solvent molecules produces a Coulomb explosion with the consequent release of protons with kinetic energy in the few electronvolts range, which collide with the surrounding molecules in solution inducing further chemical reactions. In particular, we observe proton collisions with the solute molecule DR, which leads to a complete ring opening. In DNA, damage to the DR moiety may lead to DNA strand breaking. This mechanism can be understood as one of the possible steps in the radiation-induced fragmentation of DNA chains. Copyright © 2018 American Chemical Society. |
Effect of puckering motion and hydrogen bond formation on the vibrational circular dichroism spectrum of a flexible molecule: The case of (: S)-1-indanol Article de journal K Le Barbu-Debus; A Scherrer; A Bouchet; D Sebastiani; R Vuilleumier; A Zehnacker Physical Chemistry Chemical Physics, 20 (21), p. 14635–14646, 2018. @article{LeBarbu-Debus:2018, title = {Effect of puckering motion and hydrogen bond formation on the vibrational circular dichroism spectrum of a flexible molecule: The case of (: S)-1-indanol}, author = {K Le Barbu-Debus and A Scherrer and A Bouchet and D Sebastiani and R Vuilleumier and A Zehnacker}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048438873&doi=10.1039%2fc8cp01695j&partnerID=40&md5=37c577390251d7b760ddadd0174f6e11}, doi = {10.1039/c8cp01695j}, year = {2018}, date = {2018-01-01}, journal = {Physical Chemistry Chemical Physics}, volume = {20}, number = {21}, pages = {14635--14646}, abstract = {The influence of flexibility and hydrogen bond formation on the IR absorption and vibrational circular dichroism (VCD) spectrum of a floppy protic molecule, namely, (S)-1-indanol, is studied in both non-polar CCl4 and polar DMSO solvents. The experimental IR absorption and VCD spectra obtained by Fourier transform spectroscopy are interpreted using both static density functional theory (DFT) calculations and first principles molecular dynamics (FPMD) within DFT, using the nuclear velocity perturbation theory (NVPT). Simulation of the spectra based on static optimised geometries is not sufficient in CCl4 and going beyond static calculations is mandatory for satisfactorily reproducing the VCD spectra. The FPMD results obtained in DMSO indicate that (S)-1-indanol is hydrogen-bonded to one DMSO molecule. As a result, static "cluster-in-the-bulk" DFT calculations in which the solute-solvent interaction is modeled as the most stable (S)-1-indanol:DMSO complexes in a DMSO continuum yield satisfactory agreement with the experiment. Correspondence between experimental and simulated spectra is slightly improved when the VCD spectrum is calculated as the summed contributions of snapshots extracted from FPMD trajectories, due to better sampling of the potential-energy surface. Finally, NVPT calculations further improve the description of experimental spectra by taking into account higher-energy structures, which are not necessary local minima. © the Owner Societies 2018.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The influence of flexibility and hydrogen bond formation on the IR absorption and vibrational circular dichroism (VCD) spectrum of a floppy protic molecule, namely, (S)-1-indanol, is studied in both non-polar CCl4 and polar DMSO solvents. The experimental IR absorption and VCD spectra obtained by Fourier transform spectroscopy are interpreted using both static density functional theory (DFT) calculations and first principles molecular dynamics (FPMD) within DFT, using the nuclear velocity perturbation theory (NVPT). Simulation of the spectra based on static optimised geometries is not sufficient in CCl4 and going beyond static calculations is mandatory for satisfactorily reproducing the VCD spectra. The FPMD results obtained in DMSO indicate that (S)-1-indanol is hydrogen-bonded to one DMSO molecule. As a result, static "cluster-in-the-bulk" DFT calculations in which the solute-solvent interaction is modeled as the most stable (S)-1-indanol:DMSO complexes in a DMSO continuum yield satisfactory agreement with the experiment. Correspondence between experimental and simulated spectra is slightly improved when the VCD spectrum is calculated as the summed contributions of snapshots extracted from FPMD trajectories, due to better sampling of the potential-energy surface. Finally, NVPT calculations further improve the description of experimental spectra by taking into account higher-energy structures, which are not necessary local minima. © the Owner Societies 2018. |
Chiral Crystal Packing Induces Enhancement of Vibrational Circular Dichroism Article de journal S Jähnigen; A Scherrer; R Vuilleumier; D Sebastiani Angewandte Chemie - International Edition, 57 (40), p. 13344–13348, 2018. @article{Jahnigen:2018, title = {Chiral Crystal Packing Induces Enhancement of Vibrational Circular Dichroism}, author = {S J\"{a}hnigen and A Scherrer and R Vuilleumier and D Sebastiani}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053736179&doi=10.1002%2fanie.201805671&partnerID=40&md5=70aebeca5f30f9ef94548575f45a28d7}, doi = {10.1002/anie.201805671}, year = {2018}, date = {2018-01-01}, journal = {Angewandte Chemie - International Edition}, volume = {57}, number = {40}, pages = {13344--13348}, abstract = {We demonstrate that molecular vibrations with originally low or zero intensity in a vibrational circular dichroism (VCD) spectrum attain chirality in molecular crystals by coordinated motion of the atoms. Ab initio molecular dynamics simulations of anharmonic solid-state VCD spectra of l-alanine crystals reveal how coherent vibrational modes exploit the space group's chirality, leading to non-local, enhanced VCD features, most significantly in the carbonyl region of the spectrum. The VCD-enhanced signal is ascribed to a helical arrangement of the oscillators in the crystal layers. No structural irregularities need to be considered to explain the amplification, but a crucial point lies in the polarization of charge, which requires an accurate description of the electronic structure. Delivering a quantitative atomic conception of supramolecular chirality induction, our ab initio scheme is applicable well beyond molecular crystals, for example, to address VCD in proteins and related compounds. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim}, keywords = {}, pubstate = {published}, tppubtype = {article} } We demonstrate that molecular vibrations with originally low or zero intensity in a vibrational circular dichroism (VCD) spectrum attain chirality in molecular crystals by coordinated motion of the atoms. Ab initio molecular dynamics simulations of anharmonic solid-state VCD spectra of l-alanine crystals reveal how coherent vibrational modes exploit the space group's chirality, leading to non-local, enhanced VCD features, most significantly in the carbonyl region of the spectrum. The VCD-enhanced signal is ascribed to a helical arrangement of the oscillators in the crystal layers. No structural irregularities need to be considered to explain the amplification, but a crucial point lies in the polarization of charge, which requires an accurate description of the electronic structure. Delivering a quantitative atomic conception of supramolecular chirality induction, our ab initio scheme is applicable well beyond molecular crystals, for example, to address VCD in proteins and related compounds. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim |
Renewable Hydride Donors for the Catalytic Reduction of CO2: A Thermodynamic and Kinetic Study Article de journal A Alherz; C -H Lim; Y -C Kuo; P Lehman; J Cha; J T Hynes; C B Musgrave Journal of Physical Chemistry B, 122 (44), p. 10179–10189, 2018. @article{Alherz:2018, title = {Renewable Hydride Donors for the Catalytic Reduction of CO2: A Thermodynamic and Kinetic Study}, author = {A Alherz and C -H Lim and Y -C Kuo and P Lehman and J Cha and J T Hynes and C B Musgrave}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056209325&doi=10.1021%2facs.jpcb.8b08536&partnerID=40&md5=e068bb8f9f1e8c2ba382c4ae40fd9b3a}, doi = {10.1021/acs.jpcb.8b08536}, year = {2018}, date = {2018-01-01}, journal = {Journal of Physical Chemistry B}, volume = {122}, number = {44}, pages = {10179--10189}, abstract = {Increasing atmospheric CO2 concentration and dwindling fossil fuel supply necessitate the search for efficient methods for CO2 conversion to fuels. Assorted studies have shown pyridine and its derivatives capable of (photo)electrochemically reducing CO2 to methanol, and some mechanistic interpretations have been proposed. Here, we analyze the thermodynamic and kinetic aspects of the efficacy of pyridines as hydride-donating catalytic reagents that transfer hydrides via their dihydropyridinic form. We investigate both the effects of functionalizing pyridinic derivatives with electron-donating and electron-withdrawing groups on hydride-transfer catalyst strength, assessed via their hydricity (thermodynamic ability) and nucleophilicity (kinetic ability), and catalyst recyclability, assessed via their reduction potential. We find that pyridines substituted with electron-donating groups have stronger hydride-donating ability (having lower hydricity and larger nucleophilicity values), but are less efficiently recycled (having more negative reduction potentials). In contrast, pyridines substituted with electron-withdrawing groups are more efficiently recycled, but are weaker hydride donors. Functional group modification favorably tunes hydride strength or efficiency, but not both. We attribute this problematic coupling between the strength and recyclability of pyridinic hydrides to their aromatic nature and suggest several avenues for overcoming this difficulty. © 2018 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Increasing atmospheric CO2 concentration and dwindling fossil fuel supply necessitate the search for efficient methods for CO2 conversion to fuels. Assorted studies have shown pyridine and its derivatives capable of (photo)electrochemically reducing CO2 to methanol, and some mechanistic interpretations have been proposed. Here, we analyze the thermodynamic and kinetic aspects of the efficacy of pyridines as hydride-donating catalytic reagents that transfer hydrides via their dihydropyridinic form. We investigate both the effects of functionalizing pyridinic derivatives with electron-donating and electron-withdrawing groups on hydride-transfer catalyst strength, assessed via their hydricity (thermodynamic ability) and nucleophilicity (kinetic ability), and catalyst recyclability, assessed via their reduction potential. We find that pyridines substituted with electron-donating groups have stronger hydride-donating ability (having lower hydricity and larger nucleophilicity values), but are less efficiently recycled (having more negative reduction potentials). In contrast, pyridines substituted with electron-withdrawing groups are more efficiently recycled, but are weaker hydride donors. Functional group modification favorably tunes hydride strength or efficiency, but not both. We attribute this problematic coupling between the strength and recyclability of pyridinic hydrides to their aromatic nature and suggest several avenues for overcoming this difficulty. © 2018 American Chemical Society. |
Predicting Hydride Donor Strength via Quantum Chemical Calculations of Hydride Transfer Activation Free Energy Article de journal A Alherz; C -H Lim; J T Hynes; C B Musgrave Journal of Physical Chemistry B, 122 (3), p. 1278-1288, 2018, (cited By 7). @article{Alherz20181278, title = {Predicting Hydride Donor Strength via Quantum Chemical Calculations of Hydride Transfer Activation Free Energy}, author = {A Alherz and C -H Lim and J T Hynes and C B Musgrave}, doi = {10.1021/acs.jpcb.7b12093}, year = {2018}, date = {2018-01-01}, journal = {Journal of Physical Chemistry B}, volume = {122}, number = {3}, pages = {1278-1288}, abstract = {We propose a method to approximate the kinetic properties of hydride donor species by relating the nucleophilicity (N) of a hydride to the activation free energy $Delta$G textdaggerdbl of its corresponding hydride transfer reaction. N is a kinetic parameter related to the hydride transfer rate constant that quantifies a nucleophilic hydridic species' tendency to donate. Our method estimates N using quantum chemical calculations to compute $Delta$G textdaggerdbl for hydride transfers from hydride donors to CO 2 in solution. A linear correlation for each class of hydrides is then established between experimentally determined N values and the computationally predicted $Delta$G textdaggerdbl this relationship can then be used to predict nucleophilicity for different hydride donors within each class. This approach is employed to determine N for four different classes of hydride donors: two organic (carbon-based and benzimidazole-based) and two inorganic (boron and silicon) hydride classes. We argue that silicon and boron hydrides are driven by the formation of the more stable Si-O or B-O bond. In contrast, the carbon-based hydrides considered herein are driven by the stability acquired upon rearomatization, a feature making these species of particular interest, because they both exhibit catalytic behavior and can be recycled. textcopyright 2017 American Chemical Society.}, note = {cited By 7}, keywords = {}, pubstate = {published}, tppubtype = {article} } We propose a method to approximate the kinetic properties of hydride donor species by relating the nucleophilicity (N) of a hydride to the activation free energy $Delta$G textdaggerdbl of its corresponding hydride transfer reaction. N is a kinetic parameter related to the hydride transfer rate constant that quantifies a nucleophilic hydridic species' tendency to donate. Our method estimates N using quantum chemical calculations to compute $Delta$G textdaggerdbl for hydride transfers from hydride donors to CO 2 in solution. A linear correlation for each class of hydrides is then established between experimentally determined N values and the computationally predicted $Delta$G textdaggerdbl this relationship can then be used to predict nucleophilicity for different hydride donors within each class. This approach is employed to determine N for four different classes of hydride donors: two organic (carbon-based and benzimidazole-based) and two inorganic (boron and silicon) hydride classes. We argue that silicon and boron hydrides are driven by the formation of the more stable Si-O or B-O bond. In contrast, the carbon-based hydrides considered herein are driven by the stability acquired upon rearomatization, a feature making these species of particular interest, because they both exhibit catalytic behavior and can be recycled. textcopyright 2017 American Chemical Society. |
2017 |
Chapter 3: A Transition State Theory Perspective for Enzymatic Reactions: Fundamentals and Applications Article de journal J T Hynes; D Laage; I Tu~nón; V Moliner RSC Theoretical and Computational Chemistry Series, 2017-January (9), p. 54-88, 2017, (cited By 0). @article{Hynes201754, title = {Chapter 3: A Transition State Theory Perspective for Enzymatic Reactions: Fundamentals and Applications}, author = {J T Hynes and D Laage and I Tu{~n}\'{o}n and V Moliner}, doi = {10.1039/9781782626831-00054}, year = {2017}, date = {2017-01-01}, journal = {RSC Theoretical and Computational Chemistry Series}, volume = {2017-January}, number = {9}, pages = {54-88}, abstract = {In this chapter we present the basic principles of transition state theory (TST) and a number of its applications to the study of enzymatic reactions. The assumptions of TST are discussed, as are the refinements to account for the failure of those assumptions, in particular that of no recrossing of the transition state surface. The selection of a reaction coordinate and the associated generation of free energy surfaces and their importance for TST receive special attention. While TST in its usual form assumes classical nuclear motion of the reaction coordinate, it can also be applied - with a special choice of classical reaction coordinate - for enzymatic reactions involving the transfer of light particles (proton, hydride and hydrogen atom transfers), where a quantum description of their motion is required. The theory and deviations from it are illustrated and discussed in detail via applications to a number of enzyme-catalysed reactions, indicating how TST and its variants can be successfully used to obtain rate constants for these reactions, to understand important aspects of their mechanism, and to identify the sources of the catalytic effect itself. textcopyright 2017 The Royal Society of Chemistry.}, note = {cited By 0}, keywords = {}, pubstate = {published}, tppubtype = {article} } In this chapter we present the basic principles of transition state theory (TST) and a number of its applications to the study of enzymatic reactions. The assumptions of TST are discussed, as are the refinements to account for the failure of those assumptions, in particular that of no recrossing of the transition state surface. The selection of a reaction coordinate and the associated generation of free energy surfaces and their importance for TST receive special attention. While TST in its usual form assumes classical nuclear motion of the reaction coordinate, it can also be applied - with a special choice of classical reaction coordinate - for enzymatic reactions involving the transfer of light particles (proton, hydride and hydrogen atom transfers), where a quantum description of their motion is required. The theory and deviations from it are illustrated and discussed in detail via applications to a number of enzyme-catalysed reactions, indicating how TST and its variants can be successfully used to obtain rate constants for these reactions, to understand important aspects of their mechanism, and to identify the sources of the catalytic effect itself. textcopyright 2017 The Royal Society of Chemistry. |
Solvation Dynamics in Liquid Water. III. Energy Fluxes and Structural Changes Article de journal R Rey; J T Hynes Journal of Physical Chemistry B, 121 (6), p. 1377-1385, 2017, (cited By 4). @article{Rey20171377, title = {Solvation Dynamics in Liquid Water. III. Energy Fluxes and Structural Changes}, author = {R Rey and J T Hynes}, doi = {10.1021/acs.jpcb.6b11805}, year = {2017}, date = {2017-01-01}, journal = {Journal of Physical Chemistry B}, volume = {121}, number = {6}, pages = {1377-1385}, abstract = {In previous installments it has been shown how a detailed analysis of energy fluxes induced by electronic excitation of a solute can provide a quantitative understanding of the dominant molecular energy flow channels characterizing solvation - and in particular, hydration - relaxation dynamics. Here this work and power approach is complemented with a detailed characterization of the changes induced by such energy fluxes. We first examine the water solvent's spatial and orientational distributions and the assorted energy fluxes in the various hydration shells of the solute to provide a molecular picture of the relaxation. The latter analysis is also used to address the issue of a possible "inverse snowball" effect, an ansatz concerning the time scales of the different hydration shells to reach equilibrium. We then establish a link between the instantaneous torque, exerted on the water solvent neighbors' principal rotational axes immediately after excitation and the final energy transferred into those librational motions, which are the dominant short-time energy receptor. textcopyright 2017 American Chemical Society.}, note = {cited By 4}, keywords = {}, pubstate = {published}, tppubtype = {article} } In previous installments it has been shown how a detailed analysis of energy fluxes induced by electronic excitation of a solute can provide a quantitative understanding of the dominant molecular energy flow channels characterizing solvation - and in particular, hydration - relaxation dynamics. Here this work and power approach is complemented with a detailed characterization of the changes induced by such energy fluxes. We first examine the water solvent's spatial and orientational distributions and the assorted energy fluxes in the various hydration shells of the solute to provide a molecular picture of the relaxation. The latter analysis is also used to address the issue of a possible "inverse snowball" effect, an ansatz concerning the time scales of the different hydration shells to reach equilibrium. We then establish a link between the instantaneous torque, exerted on the water solvent neighbors' principal rotational axes immediately after excitation and the final energy transferred into those librational motions, which are the dominant short-time energy receptor. textcopyright 2017 American Chemical Society. |