You will find below the publication list of our pole.
For the publication list of each pole member, please see his/her personal webpage.
2005 |
Reactant concentrations from fluorescence correlation spectroscopy with tailored fluorescent probes. An example of local calibration-free pH measurement Article de journal S Charier; A Meglio; D Alcor; E Cogné-Laage; J -F Allemand; L Jullien; A Lemarchand Journal of the American Chemical Society, 127 (44), p. 15491–15505, 2005. @article{Charier:2005, title = {Reactant concentrations from fluorescence correlation spectroscopy with tailored fluorescent probes. An example of local calibration-free pH measurement}, author = {S Charier and A Meglio and D Alcor and E Cogn\'{e}-Laage and J -F Allemand and L Jullien and A Lemarchand}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-27644487200&doi=10.1021%2fja053909w&partnerID=40&md5=63004e877da68d3e2aa7472577479c8d}, doi = {10.1021/ja053909w}, year = {2005}, date = {2005-01-01}, journal = {Journal of the American Chemical Society}, volume = {127}, number = {44}, pages = {15491--15505}, abstract = {The present account is concerned with the measurement of local reactant concentrations by observing specific fluorescent probes in fluorescence correlation spectroscopy (FCS). The Theoretical Analysis section revisits the photophysical, thermodynamic, and kinetic information that is contained in the corresponding FCS correlation curves. In particular, we examine the conditions under which FCS is revealed as a superior tool to measure concentrations of reactive species. Careful molecular engineering of the specific fluorescent probes that simultaneously integrates photophysical, thermodynamic, and kinetic constraints will be required to benefit most from FCS. We illustrate the FCS titration approach with a series of fluorescent probes that we tailored to measure pH at around 4-6 by FCS after two-photon excitation. We show that an optimal design allows one to access pH without any preliminary calibrations such as the determination of the protonation constant or the photophysical properties of the fluorescent probe. © 2005 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The present account is concerned with the measurement of local reactant concentrations by observing specific fluorescent probes in fluorescence correlation spectroscopy (FCS). The Theoretical Analysis section revisits the photophysical, thermodynamic, and kinetic information that is contained in the corresponding FCS correlation curves. In particular, we examine the conditions under which FCS is revealed as a superior tool to measure concentrations of reactive species. Careful molecular engineering of the specific fluorescent probes that simultaneously integrates photophysical, thermodynamic, and kinetic constraints will be required to benefit most from FCS. We illustrate the FCS titration approach with a series of fluorescent probes that we tailored to measure pH at around 4-6 by FCS after two-photon excitation. We show that an optimal design allows one to access pH without any preliminary calibrations such as the determination of the protonation constant or the photophysical properties of the fluorescent probe. © 2005 American Chemical Society. |
Shear-induced permeation and fusion of lipid vesicles Article de journal A -L Bernard; M -A Guedeau-Boudeville; V Marchi-Artzner; T Gulik-Krzywicki; J -M Di Meglio; L Jullien Journal of Colloid and Interface Science, 287 (1), p. 298–306, 2005. @article{Bernard:2005, title = {Shear-induced permeation and fusion of lipid vesicles}, author = {A -L Bernard and M -A Guedeau-Boudeville and V Marchi-Artzner and T Gulik-Krzywicki and J -M Di Meglio and L Jullien}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-19444367593&doi=10.1016%2fj.jcis.2004.12.019&partnerID=40&md5=b145a8f86b25aa706590e9a5d91f8b92}, doi = {10.1016/j.jcis.2004.12.019}, year = {2005}, date = {2005-01-01}, journal = {Journal of Colloid and Interface Science}, volume = {287}, number = {1}, pages = {298--306}, abstract = {This paper introduces a novel approach to controlling membrane permeability in free unilamellar vesicles using shearing in the presence of a detergent with a large head-group to tune pore formation. Such shear-induced permeation could offer a simple means of postencapsulating bioactive molecules to prepare vesicle vectors for drug delivery. Using UV absorption, fluorescence emission, dynamic light scattering, and electron microscopy, we investigated the membrane permeability and the morphology of unilamellar lipid vesicles (diameter in the range 50-400 nm) subjected to a shear stress in the presence of a small amount of nonionic surfactant (Brij 76). Shear-induced leakage and fusion events were observed. We analyzed the significance of the vesicle size, the shear rate, and the surfactant-to-lipid ratio for the observed phenomena. The present approach is evaluated for postloading of preformed vesicles. © 2004 Elsevier Inc. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This paper introduces a novel approach to controlling membrane permeability in free unilamellar vesicles using shearing in the presence of a detergent with a large head-group to tune pore formation. Such shear-induced permeation could offer a simple means of postencapsulating bioactive molecules to prepare vesicle vectors for drug delivery. Using UV absorption, fluorescence emission, dynamic light scattering, and electron microscopy, we investigated the membrane permeability and the morphology of unilamellar lipid vesicles (diameter in the range 50-400 nm) subjected to a shear stress in the presence of a small amount of nonionic surfactant (Brij 76). Shear-induced leakage and fusion events were observed. We analyzed the significance of the vesicle size, the shear rate, and the surfactant-to-lipid ratio for the observed phenomena. The present approach is evaluated for postloading of preformed vesicles. © 2004 Elsevier Inc. All rights reserved. |
Spectroscopic study of the chromophore–protein association and primary photoinduced events in the photoreceptor of Blepharisma japonicum Article de journal P Plaza; M Mahet; M M Martin; N Angelini; M Malatesta; G Checcucci; F Lenci Photochemical and Photobiological Sciences, 4 (9), p. 754–761, 2005. @article{Plaza:2005a, title = {Spectroscopic study of the chromophore\textendashprotein association and primary photoinduced events in the photoreceptor of Blepharisma japonicum}, author = {P Plaza and M Mahet and M M Martin and N Angelini and M Malatesta and G Checcucci and F Lenci}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-25444441088&doi=10.1039%2fb417086e&partnerID=40&md5=dd3ced0e70c892fd5e0234b3abb6ea0f}, doi = {10.1039/b417086e}, year = {2005}, date = {2005-01-01}, journal = {Photochemical and Photobiological Sciences}, volume = {4}, number = {9}, pages = {754--761}, abstract = {Blepharisma japonicum is a ciliated protozoan exhibiting a strong step-up photophobic response upon illumination. The photoreceptor chromophores responsible for this response have been identified to be hypericin-like chromophores (blepharismin and oxyblepharismin), complexed to a 200 kDa non-water-soluble protein. The present work opens up new perspectives on the primary phototransduction steps of B. japonicum’s light perception through a joined approach by steady-state fluorescence spectroscopy, time-resolved fluorescence anisotropy and sub-picosecond transient absorption spectroscopy. The free chromophore of the light-adapted form of the cell (oxyblepharismin) was studied in various solvents and its spectroscopic properties, as well as its primary excited-state reactivity, compared with those of the corresponding pigment\textendashprotein complex, extracted by phosphate-concentration-step chromatography on a hydroxyapatite column. Fluorescence anisotropy together with SDS PAGE electrophoresis results confirm that oxyblepharismin is non-covalently bound to the apoprotein and show that, in the excited state, it is free to rotate in all directions within the binding site where it experiences a large local viscosity. Time-resolved anisotropy measurements on aromatic amino acids confirm that the molecular weight of the protein is of the order of 200 kDa. Although showing very similar steady-state spectra, free oxyblepharismin and its protein complex have noticeably different excited-state behaviours. In particular, the protein complex exhibits a pronounced short-lived absorption feature in the 640\textendash750 nm range, decaying biexponentially in 4 ps and 56 ps. Those decays, also observed in other spectral regions, are not found in the corresponding kinetics of the isolated pigment in solution. This early behaviour of the protein complex might be the signature of the primary phototransduction process, possibly involving an electron transfer from the pigment to a neighbouring protein acceptor residue as it had been suggested in previous studies. © 2005 The Royal Society of Chemistry and Owner Societies.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Blepharisma japonicum is a ciliated protozoan exhibiting a strong step-up photophobic response upon illumination. The photoreceptor chromophores responsible for this response have been identified to be hypericin-like chromophores (blepharismin and oxyblepharismin), complexed to a 200 kDa non-water-soluble protein. The present work opens up new perspectives on the primary phototransduction steps of B. japonicum’s light perception through a joined approach by steady-state fluorescence spectroscopy, time-resolved fluorescence anisotropy and sub-picosecond transient absorption spectroscopy. The free chromophore of the light-adapted form of the cell (oxyblepharismin) was studied in various solvents and its spectroscopic properties, as well as its primary excited-state reactivity, compared with those of the corresponding pigment–protein complex, extracted by phosphate-concentration-step chromatography on a hydroxyapatite column. Fluorescence anisotropy together with SDS PAGE electrophoresis results confirm that oxyblepharismin is non-covalently bound to the apoprotein and show that, in the excited state, it is free to rotate in all directions within the binding site where it experiences a large local viscosity. Time-resolved anisotropy measurements on aromatic amino acids confirm that the molecular weight of the protein is of the order of 200 kDa. Although showing very similar steady-state spectra, free oxyblepharismin and its protein complex have noticeably different excited-state behaviours. In particular, the protein complex exhibits a pronounced short-lived absorption feature in the 640–750 nm range, decaying biexponentially in 4 ps and 56 ps. Those decays, also observed in other spectral regions, are not found in the corresponding kinetics of the isolated pigment in solution. This early behaviour of the protein complex might be the signature of the primary phototransduction process, possibly involving an electron transfer from the pigment to a neighbouring protein acceptor residue as it had been suggested in previous studies. © 2005 The Royal Society of Chemistry and Owner Societies. |
Stochastic resonance to control diffusive motion in chemistry Article de journal D Alcor; J -F Allemand; E Cogné-Laage; V Croquette; F Ferrage; L Jullien; A Kononov; A Lemarchand Journal of Physical Chemistry B, 109 (3), p. 1318–1328, 2005. @article{Alcor:2005, title = {Stochastic resonance to control diffusive motion in chemistry}, author = {D Alcor and J -F Allemand and E Cogn\'{e}-Laage and V Croquette and F Ferrage and L Jullien and A Kononov and A Lemarchand}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-13444261095&doi=10.1021%2fjp0468307&partnerID=40&md5=16630c2883d35adddf4ee32f3b8185c1}, doi = {10.1021/jp0468307}, year = {2005}, date = {2005-01-01}, journal = {Journal of Physical Chemistry B}, volume = {109}, number = {3}, pages = {1318--1328}, abstract = {This paper reports on a novel procedure to tune the effective diffusion coefficient of a field-sensitive reactant in the presence of a periodic external field. We investigate the motion of two negatively charged azo dyes interacting with α-cyclodextrin (α-CD) upon action of a periodic square wave electrical field. We show that the dyes exhibit an effective diffusion coefficient Deff that depends on the rate constants for dye complexation within α-CD, the period and the amplitude of the field. UV-vis absorption, gradient field 1H NMR, and fluorescence correlation spectroscopy (FCS) after two photon excitation are used to evidence that Deff may be increased far beyond its intrinsic value when specific relations interpreted as a stochastic resonance are fulfilled. The present results may find useful applications in chemical kinetics as well as for molecular sorting.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This paper reports on a novel procedure to tune the effective diffusion coefficient of a field-sensitive reactant in the presence of a periodic external field. We investigate the motion of two negatively charged azo dyes interacting with α-cyclodextrin (α-CD) upon action of a periodic square wave electrical field. We show that the dyes exhibit an effective diffusion coefficient Deff that depends on the rate constants for dye complexation within α-CD, the period and the amplitude of the field. UV-vis absorption, gradient field 1H NMR, and fluorescence correlation spectroscopy (FCS) after two photon excitation are used to evidence that Deff may be increased far beyond its intrinsic value when specific relations interpreted as a stochastic resonance are fulfilled. The present results may find useful applications in chemical kinetics as well as for molecular sorting. |
Stochastic resonances and highly selective separation methods: Application to the detection of DNA mutations Inproceedings A E Torres; L Jullien; A Lemarchand AIP Conference Proceedings, p. 639–642, 2005. @inproceedings{Torres:2005, title = {Stochastic resonances and highly selective separation methods: Application to the detection of DNA mutations}, author = {A E Torres and L Jullien and A Lemarchand}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33749498968&doi=10.1063%2f1.2036833&partnerID=40&md5=5941f3fb20dace3449457cf9a9c84174}, doi = {10.1063/1.2036833}, year = {2005}, date = {2005-01-01}, booktitle = {AIP Conference Proceedings}, volume = {780}, pages = {639--642}, abstract = {The application of a time-periodic field on a chemical reacting system dramatically increases the dispersion coefficient of one reactant, provided that the periods of the field and the chemical reaction are in resonant conditions. We show how this principle can be used to perform highly selective separation and we illustrate the building-up of an experimental setup for detecting DNA mutations. © 2005 American Institute of Physics.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } The application of a time-periodic field on a chemical reacting system dramatically increases the dispersion coefficient of one reactant, provided that the periods of the field and the chemical reaction are in resonant conditions. We show how this principle can be used to perform highly selective separation and we illustrate the building-up of an experimental setup for detecting DNA mutations. © 2005 American Institute of Physics. |
Symmetry-broken reactant motion upon phase-related symmetrically modulated excitations: Application to highly selective molecular sorting Article de journal A Lemarchand; L Jullien Journal of Physical Chemistry A, 109 (25), p. 5770–5776, 2005. @article{Lemarchand:2005, title = {Symmetry-broken reactant motion upon phase-related symmetrically modulated excitations: Application to highly selective molecular sorting}, author = {A Lemarchand and L Jullien}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-22744450493&doi=10.1021%2fjp0509156&partnerID=40&md5=3b13ba577487993b87635936ce16251d}, doi = {10.1021/jp0509156}, year = {2005}, date = {2005-01-01}, journal = {Journal of Physical Chemistry A}, volume = {109}, number = {25}, pages = {5770--5776}, abstract = {This paper introduces a separation protocol relying on affinity chromatography that exhibits unprecedented selectivities. We submit the mixture contained in the separative medium to the simultaneous action of two symmetrically modulated excitations. The first is a uniform periodic field (e.g., electric field) with zero mean value, whereas the second is the periodic modulation of a thermodynamic parameter such as the temperature. Under appropriate tuning of the modulations with the dynamics of the discriminating chemical reaction, we predict a symmetry breaking of molecular motion: the mixture components that are addressed by their rate constants exhibit an oriented motion for a particular phase relation between the modulations of the field and the thermodynamic parameter. The resulting velocity of the mixture components depends on the rate constants and on a conjugated thermodynamic value such as the standard enthalpy of the discrimination process in the case of a temperature modulation. In particular, it may be possible to separate mixture components with identical rate constants. We use the present approach to design a protocol to sort nucleic acids by their sequence. © 2005 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This paper introduces a separation protocol relying on affinity chromatography that exhibits unprecedented selectivities. We submit the mixture contained in the separative medium to the simultaneous action of two symmetrically modulated excitations. The first is a uniform periodic field (e.g., electric field) with zero mean value, whereas the second is the periodic modulation of a thermodynamic parameter such as the temperature. Under appropriate tuning of the modulations with the dynamics of the discriminating chemical reaction, we predict a symmetry breaking of molecular motion: the mixture components that are addressed by their rate constants exhibit an oriented motion for a particular phase relation between the modulations of the field and the thermodynamic parameter. The resulting velocity of the mixture components depends on the rate constants and on a conjugated thermodynamic value such as the standard enthalpy of the discrimination process in the case of a temperature modulation. In particular, it may be possible to separate mixture components with identical rate constants. We use the present approach to design a protocol to sort nucleic acids by their sequence. © 2005 American Chemical Society. |
Tuning the effective molecular diffusion: A step toward control over oriented molecular motion Article de journal D Alcor; J -F Allemand; I Aujard; T Barilero; J -B Baudin; C Benbrahim; D Bensimon; A Bourdoncle; S Charier; E Cogné-Laage; V Croquette; A Estevez-Torres; N Gagey; L Jullien; A Lemarchand; H Lemarchand; A Meglio; P Neveu; O Ruel Actualite Chimique, (284), p. 9–15, 2005. @article{Alcor:2005a, title = {Tuning the effective molecular diffusion: A step toward control over oriented molecular motion}, author = {D Alcor and J -F Allemand and I Aujard and T Barilero and J -B Baudin and C Benbrahim and D Bensimon and A Bourdoncle and S Charier and E Cogn\'{e}-Laage and V Croquette and A Estevez-Torres and N Gagey and L Jullien and A Lemarchand and H Lemarchand and A Meglio and P Neveu and O Ruel}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-20244376002&partnerID=40&md5=3db1ae540bc4b45e162796d974c4726b}, year = {2005}, date = {2005-01-01}, journal = {Actualite Chimique}, number = {284}, pages = {9--15}, abstract = {« Control » over disordered molecular motion is not a dream as clearly evidenced by living beings. In the reactive mixture of cell cytoplasm, molecules perform an oriented ballet. Astonishment of the chemist should not here originate only from the motion, but much more from its orientation as well as from its selectivity. Much has to be analyzed and a lot has to be imagined to account for this observation. We attempt to reproduce a few basic features of biological motors in simpler « molecular cargos ». This goal is difficult. We first chose to exert an analogous control over molecular motion in a less compelling situation, that of diffusion: the orientation of motion is lost, in contrast selectivity is maintained. We recently demonstrated that it is possible to « fish » any reactant in a mixture submitted to the action of an appropriate uniform and time-periodic field when its period is matched to the lifetimes of the interconverting states of the desired reactant. Under such conditions, the effective diffusion of the latter can be considerably increased and it becomes possible to selectively perform its extraction.}, keywords = {}, pubstate = {published}, tppubtype = {article} } « Control » over disordered molecular motion is not a dream as clearly evidenced by living beings. In the reactive mixture of cell cytoplasm, molecules perform an oriented ballet. Astonishment of the chemist should not here originate only from the motion, but much more from its orientation as well as from its selectivity. Much has to be analyzed and a lot has to be imagined to account for this observation. We attempt to reproduce a few basic features of biological motors in simpler « molecular cargos ». This goal is difficult. We first chose to exert an analogous control over molecular motion in a less compelling situation, that of diffusion: the orientation of motion is lost, in contrast selectivity is maintained. We recently demonstrated that it is possible to « fish » any reactant in a mixture submitted to the action of an appropriate uniform and time-periodic field when its period is matched to the lifetimes of the interconverting states of the desired reactant. Under such conditions, the effective diffusion of the latter can be considerably increased and it becomes possible to selectively perform its extraction. |
2004 |
An efficient fluorescent probe for ratiometric pH measurements in aqueous solutions Article de journal S Charier; O Ruel; J -B Baudin; D Alcor; J -F Allemand; A Meglio; L Jullien Angewandte Chemie - International Edition, 43 (36), p. 4785–4788, 2004. @article{Charier:2004, title = {An efficient fluorescent probe for ratiometric pH measurements in aqueous solutions}, author = {S Charier and O Ruel and J -B Baudin and D Alcor and J -F Allemand and A Meglio and L Jullien}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-4644247115&doi=10.1002%2fanie.200460557&partnerID=40&md5=3e99219ed8a64d67a68d2c1a7bff133b}, doi = {10.1002/anie.200460557}, year = {2004}, date = {2004-01-01}, journal = {Angewandte Chemie - International Edition}, volume = {43}, number = {36}, pages = {4785--4788}, abstract = {Just as litmus paper changes from red to blue with an increase in pH, so the fluorescence emission of the oxazole derivative 1 shifts from green to blue. Ratiometric measurements of the fluorescence emissions of the two species, after one- or two-photon excitation, allow 1 to be employed as a pH sensor over the mid-pH range.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Just as litmus paper changes from red to blue with an increase in pH, so the fluorescence emission of the oxazole derivative 1 shifts from green to blue. Ratiometric measurements of the fluorescence emissions of the two species, after one- or two-photon excitation, allow 1 to be employed as a pH sensor over the mid-pH range. |
Chemical structure effect on the excited-state relaxation dynamics of the PYP chromophore Inproceedings A Espagne; P Changenet-Barret; S Charier; J -B Baudin; L Jullien; P Plaza; M M Martin Martin, M M; Hynes, J T (Ed.): VIth International Conference on Femtochemistry, p. 421-424, Elsevier, 2004. @inproceedings{RN88, title = {Chemical structure effect on the excited-state relaxation dynamics of the PYP chromophore}, author = {A Espagne and P Changenet-Barret and S Charier and J -B Baudin and L Jullien and P Plaza and M M Martin}, editor = {M M Martin and J T Hynes}, year = {2004}, date = {2004-01-01}, booktitle = {VIth International Conference on Femtochemistry}, pages = {421-424}, publisher = {Elsevier}, series = {Femtochemistry and Femtobiology: Ultrafast Events in Molecular Science}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Competition and symbiosis in a chemical world Article de journal A Lemarchand; L Jullien Journal of Physical Chemistry B, 108 (31), p. 11782–11791, 2004. @article{Lemarchand:2004, title = {Competition and symbiosis in a chemical world}, author = {A Lemarchand and L Jullien}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-4143134116&doi=10.1021%2fjp0379392&partnerID=40&md5=78471d67bd8e500016462d556b193707}, doi = {10.1021/jp0379392}, year = {2004}, date = {2004-01-01}, journal = {Journal of Physical Chemistry B}, volume = {108}, number = {31}, pages = {11782--11791}, abstract = {A possible road for the emergence of complexity in artificial inhomogeneous chemical systems is analyzed. We build a reaction-diffusion model inspired from a surfactant-based scheme leading to the formation of micelles and vesicles. Our model only relies on autocatalysis and the existence of a critical concentration. Depending on the parameter values of the extended dynamical system, this simple model already accounts for typical behaviors of living organisms. In particular, competition and different types of symbiotic relationships are reproduced.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A possible road for the emergence of complexity in artificial inhomogeneous chemical systems is analyzed. We build a reaction-diffusion model inspired from a surfactant-based scheme leading to the formation of micelles and vesicles. Our model only relies on autocatalysis and the existence of a critical concentration. Depending on the parameter values of the extended dynamical system, this simple model already accounts for typical behaviors of living organisms. In particular, competition and different types of symbiotic relationships are reproduced. |
Early molecular events in the photoactive yellow protein: Role of the chromophore photophysics Article de journal P Changenet-Barret; A Espagne; S Charier; J -B Baudin; L Jullien; P Plaza; K J Hellingwerf; M M Martin Photochemical and Photobiological Sciences, 3 (8), p. 823–829, 2004. @article{Changenet-Barret:2004, title = {Early molecular events in the photoactive yellow protein: Role of the chromophore photophysics}, author = {P Changenet-Barret and A Espagne and S Charier and J -B Baudin and L Jullien and P Plaza and K J Hellingwerf and M M Martin}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-4644243446&doi=10.1039%2fb400398e&partnerID=40&md5=45520bcadbdf2612c16ef874b207d73b}, doi = {10.1039/b400398e}, year = {2004}, date = {2004-01-01}, journal = {Photochemical and Photobiological Sciences}, volume = {3}, number = {8}, pages = {823--829}, abstract = {We report a comparative study of the isomerization reaction in native and denatured photoactive yellow protein (PYP) and in various chromophore analogues in their trans deprotonated form. The excited-state relaxation dynamics was followed by subpicosecond transient absorption and gain spectroscopy. The free p-hydroxycinnamate (pCA2−) and its amide analogue (pCM-) are found to display a quite different transient spectroscopy from that of PYP. The excited-state deactivation leads to the formation of the ground-state cis isomer without any detectable intermediate with a mechanism comparable to trans-stilbene photoisomerization. On the contrary, the early stage of the excited-state deactivation of the free thiophenyl-p-hydroxycinnamate (pCT-) and of the denatured PYP is similar to that of the native protein. It involves the formation of an intermediate absorbing in the spectral region located between the bleaching and gain bands in less than 2 ps. However, in these two cases, the formation of the cis isomer has not been proved yet. This difference with pCA- and pCM- might result from the fact that, in the thioester substituted chromophore, simultaneous population of two quasi-degenerate excited states occurs upon excitation. This comparative study highlights the determining role of the chromophore structure and of its intrinsic properties in the primary molecular events in native PYP. © 2004 The Royal Society of Chemistry and Owner Societies.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We report a comparative study of the isomerization reaction in native and denatured photoactive yellow protein (PYP) and in various chromophore analogues in their trans deprotonated form. The excited-state relaxation dynamics was followed by subpicosecond transient absorption and gain spectroscopy. The free p-hydroxycinnamate (pCA2−) and its amide analogue (pCM-) are found to display a quite different transient spectroscopy from that of PYP. The excited-state deactivation leads to the formation of the ground-state cis isomer without any detectable intermediate with a mechanism comparable to trans-stilbene photoisomerization. On the contrary, the early stage of the excited-state deactivation of the free thiophenyl-p-hydroxycinnamate (pCT-) and of the denatured PYP is similar to that of the native protein. It involves the formation of an intermediate absorbing in the spectral region located between the bleaching and gain bands in less than 2 ps. However, in these two cases, the formation of the cis isomer has not been proved yet. This difference with pCA- and pCM- might result from the fact that, in the thioester substituted chromophore, simultaneous population of two quasi-degenerate excited states occurs upon excitation. This comparative study highlights the determining role of the chromophore structure and of its intrinsic properties in the primary molecular events in native PYP. © 2004 The Royal Society of Chemistry and Owner Societies. |
Fast excited-state reaction in the photoreceptor pigment-protein complex of the ciliate Blepharisma japonicum Inproceedings M Mahet; P Plaza; M M Martin; G Checcucci; F Lenci Martin, M M; Hynes, J T (Ed.): VIth International Conference on Femtochemistry, p. 441-444, Elsevier, 2004. @inproceedings{RN89, title = {Fast excited-state reaction in the photoreceptor pigment-protein complex of the ciliate Blepharisma japonicum}, author = {M Mahet and P Plaza and M M Martin and G Checcucci and F Lenci}, editor = {M M Martin and J T Hynes}, year = {2004}, date = {2004-01-01}, booktitle = {VIth International Conference on Femtochemistry}, pages = {441-444}, publisher = {Elsevier}, series = {Femtochemistry and Femtobiology: Ultrafast Events in Molecular Science}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Formation of anionic palladium(0) complexes ligated by the trifluoroacetate ion and their reactivity in oxidative addition Article de journal C Amatore; A Jutand; F Lemaître; J L Ricard; S Kozuch; S Shaik Journal of Organometallic Chemistry, 689 (23), p. 3728–3734, 2004. @article{Amatore:2004a, title = {Formation of anionic palladium(0) complexes ligated by the trifluoroacetate ion and their reactivity in oxidative addition}, author = {C Amatore and A Jutand and F Lema\^{i}tre and J L Ricard and S Kozuch and S Shaik}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-18844439358&doi=10.1016%2fj.jorganchem.2004.05.012&partnerID=40&md5=959081b6968f83e014ddf0cca8a963ce}, doi = {10.1016/j.jorganchem.2004.05.012}, year = {2004}, date = {2004-01-01}, journal = {Journal of Organometallic Chemistry}, volume = {689}, number = {23}, pages = {3728--3734}, abstract = {As established previously for Pd(OAc)2, Pd0 complexes are formed in situ from Pd(OCOCF3)2 and n equiv. triarylphosphines (4-Z-C6H4)3P (Z = CF 3, F, Cl, H, CH3; n ≥ 3). The phosphines are the intramolecular reducing agents and are oxidized to triarylphosphine oxides. The generated Pd0 complexes are anionic species ligated by the trifluoroacetate anion: Pd0(PAr3)n(OCOCF 3)- (n = 2 or 3). Pd0(PAr3) 2(OCOCF3)- is the reactive species involved in the oxidative addition to PhI. This leads to trans-PhPd(OCOCF 3)(PPh3)2, involved in equilibrium with the cationic complex trans-[PhPd(PPh3)2(DMF)]+, instead of the expected trans-PhPdI(PPh3)2 complex. The existence of anionic Pd0 complexes ligated by the acetate or trifluoroacetate ions delivered by the precursors Pd(OAc)2 or Pd(OCOCF3)2, respectively, as well as their comparative reactivity in oxidative additions are consistent with theoretical DFT calculations. © 2004 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } As established previously for Pd(OAc)2, Pd0 complexes are formed in situ from Pd(OCOCF3)2 and n equiv. triarylphosphines (4-Z-C6H4)3P (Z = CF 3, F, Cl, H, CH3; n ≥ 3). The phosphines are the intramolecular reducing agents and are oxidized to triarylphosphine oxides. The generated Pd0 complexes are anionic species ligated by the trifluoroacetate anion: Pd0(PAr3)n(OCOCF 3)- (n = 2 or 3). Pd0(PAr3) 2(OCOCF3)- is the reactive species involved in the oxidative addition to PhI. This leads to trans-PhPd(OCOCF 3)(PPh3)2, involved in equilibrium with the cationic complex trans-[PhPd(PPh3)2(DMF)]+, instead of the expected trans-PhPdI(PPh3)2 complex. The existence of anionic Pd0 complexes ligated by the acetate or trifluoroacetate ions delivered by the precursors Pd(OAc)2 or Pd(OCOCF3)2, respectively, as well as their comparative reactivity in oxidative additions are consistent with theoretical DFT calculations. © 2004 Elsevier B.V. All rights reserved. |
Isomerization process in the native and denatured Photoactive Yellow Protein probed by subpicosecond absorption spectroscopy Inproceedings P Changenet-Barret; A Espagne; P Plaza; M M Martin; Y J Hellingwerf Martin, M M; Hynes, J T (Ed.): VIth International Conference on Femtochemistry, p. 417-420, Elsevier, 2004. @inproceedings{RN87, title = {Isomerization process in the native and denatured Photoactive Yellow Protein probed by subpicosecond absorption spectroscopy}, author = {P Changenet-Barret and A Espagne and P Plaza and M M Martin and Y J Hellingwerf}, editor = {M M Martin and J T Hynes}, year = {2004}, date = {2004-01-01}, booktitle = {VIth International Conference on Femtochemistry}, pages = {417-420}, publisher = {Elsevier}, series = {Femtochemistry and Femtobiology: Ultrafast Events in Molecular Science}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Mechanism(s) of the cobalt-catalyzed electrochemical coupling between aromatic halides and allylic acetates Article de journal P Gomes; O Buriez; E Labbe; C Gosmini; J Perichon Journal of Electroanalytical Chemistry, 562 (2), p. 255-260, 2004. @article{RID:0721150706480-12, title = {Mechanism(s) of the cobalt-catalyzed electrochemical coupling between aromatic halides and allylic acetates}, author = {P Gomes and O Buriez and E Labbe and C Gosmini and J Perichon}, year = {2004}, date = {2004-01-01}, journal = {Journal of Electroanalytical Chemistry}, volume = {562}, number = {2}, pages = {255-260}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Micelles of lipid-oligonucleotide conjugates: Implications for membrane anchoring and base pairing Article de journal C Gosse; A Boutorine; I Aujard; M Chami; A Kononov; E Cogné-Laage; J -F Allemand; J Li; L Jullien Journal of Physical Chemistry B, 108 (20), p. 6485–6497, 2004. @article{Gosse:2004, title = {Micelles of lipid-oligonucleotide conjugates: Implications for membrane anchoring and base pairing}, author = {C Gosse and A Boutorine and I Aujard and M Chami and A Kononov and E Cogn\'{e}-Laage and J -F Allemand and J Li and L Jullien}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-2642510833&partnerID=40&md5=53c7d85ed744a277e84cbf84aeee9834}, year = {2004}, date = {2004-01-01}, journal = {Journal of Physical Chemistry B}, volume = {108}, number = {20}, pages = {6485--6497}, abstract = {This report examines the organization properties of new fluorescent DNA-lipids, either alone in water or in interaction with 1-octyl-β-D- glucopyranoside micelles or egg phosphatidylcholine vesicles. We first describe the design and the syntheses of the conjugates. Then, we use UV-Vis absorption, steady-state fluorescence emission, electron microscopy, and fluorescence correlation spectroscopy after two-photon excitation to show that these DNA-lipids form spherical micelles in aqueous solution and incorporate much better in micelles than in vesicles. We also investigate the significance of the lipophilic chains of these DNA-lipids on the melting behavior of the double-stranded hybrids: in water melting curves are broadened whereas in amphiphilic assemblies duplexes melt as the unconjugated controls. This work is expected to be useful for improving the rational design of antisense medicines.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This report examines the organization properties of new fluorescent DNA-lipids, either alone in water or in interaction with 1-octyl-β-D- glucopyranoside micelles or egg phosphatidylcholine vesicles. We first describe the design and the syntheses of the conjugates. Then, we use UV-Vis absorption, steady-state fluorescence emission, electron microscopy, and fluorescence correlation spectroscopy after two-photon excitation to show that these DNA-lipids form spherical micelles in aqueous solution and incorporate much better in micelles than in vesicles. We also investigate the significance of the lipophilic chains of these DNA-lipids on the melting behavior of the double-stranded hybrids: in water melting curves are broadened whereas in amphiphilic assemblies duplexes melt as the unconjugated controls. This work is expected to be useful for improving the rational design of antisense medicines. |
Molecular sorting by stochastic resonance Article de journal D Alcor; V Croquettet; L Jullien; A Lemarchand Proceedings of the National Academy of Sciences of the United States of America, 101 (22), p. 8276–8280, 2004. @article{Alcor:2004, title = {Molecular sorting by stochastic resonance}, author = {D Alcor and V Croquettet and L Jullien and A Lemarchand}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-2942622061&doi=10.1073%2fpnas.0400663101&partnerID=40&md5=8788f849313811632d06374bd9df174a}, doi = {10.1073/pnas.0400663101}, year = {2004}, date = {2004-01-01}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {101}, number = {22}, pages = {8276--8280}, abstract = {To sort a targeted species from a mixture, we introduce a procedure that relies on the enhancement of its effective diffusion coefficient. We use the formation of a host-guest complex between α-cyclodextrin and a dye to evidence the dye dispersion when the medium is submitted to an oscillating field. In particular, we demonstrate that the effective diffusion coefficient of the dye may be increased far beyond its intrinsic value by tuning the driving field frequency in the stochastic resonance regime. We use this effect to selectively sort from a mixture a dye that is addressed by its rate constants for association with α-cyclodextrin.}, keywords = {}, pubstate = {published}, tppubtype = {article} } To sort a targeted species from a mixture, we introduce a procedure that relies on the enhancement of its effective diffusion coefficient. We use the formation of a host-guest complex between α-cyclodextrin and a dye to evidence the dye dispersion when the medium is submitted to an oscillating field. In particular, we demonstrate that the effective diffusion coefficient of the dye may be increased far beyond its intrinsic value by tuning the driving field frequency in the stochastic resonance regime. We use this effect to selectively sort from a mixture a dye that is addressed by its rate constants for association with α-cyclodextrin. |
Tuning a reaction using two-site catalysis and far-from-equilibrium conditions Article de journal A Lemarchand; L Jullien Physical Chemistry Chemical Physics, 6 (2), p. 398–405, 2004. @article{Lemarchand:2004a, title = {Tuning a reaction using two-site catalysis and far-from-equilibrium conditions}, author = {A Lemarchand and L Jullien}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0942279538&doi=10.1039%2fb306678a&partnerID=40&md5=e3871b3d5a541f07ec447fa2ec0e8ff5}, doi = {10.1039/b306678a}, year = {2004}, date = {2004-01-01}, journal = {Physical Chemistry Chemical Physics}, volume = {6}, number = {2}, pages = {398--405}, abstract = {We show that a given kinetic mechanism, appropriate for describing the evolution of concentrations in a two-site catalysis, exhibits various properties when maintaining the system far from equilibrium and varying the order of magnitude of the rate constants: tuning of reaction yield, autocatalysis and kinetic proofreading are obtained. The model, involving molecules with two coupled reactive sites, gives some hints to design simple artificial systems possessing complex properties of living systems.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We show that a given kinetic mechanism, appropriate for describing the evolution of concentrations in a two-site catalysis, exhibits various properties when maintaining the system far from equilibrium and varying the order of magnitude of the rate constants: tuning of reaction yield, autocatalysis and kinetic proofreading are obtained. The model, involving molecules with two coupled reactive sites, gives some hints to design simple artificial systems possessing complex properties of living systems. |
Ultrafast photoinduced charge transfer in fluorinated derivatives of DMABN Inproceedings S Murali; P Changenet-Barret; C Ley; P Plaza; W Rettig; M M Martin; A I Tolmachev Martin, M M; Hynes, J T (Ed.): VIth International Conference on Femtochemistry, p. 323-326, Elsevier, 2004. @inproceedings{RN86, title = {Ultrafast photoinduced charge transfer in fluorinated derivatives of DMABN}, author = {S Murali and P Changenet-Barret and C Ley and P Plaza and W Rettig and M M Martin and A I Tolmachev}, editor = {M M Martin and J T Hynes}, year = {2004}, date = {2004-01-01}, booktitle = {VIth International Conference on Femtochemistry}, pages = {323-326}, publisher = {Elsevier}, series = {Femtochemistry and Femtobiology: Ultrafast Events in Molecular Science}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
2003 |
Adhesion of Arg-Gly-Asp (RGD) peptide vesicles onto an integrin surface: Visualization of the segregation of RGD ligands into the adhesion plaques by fluorescence Article de journal V Marchi-Artzner; B Lorz; C Gosse; L Jullien; R Merkel; H Kessler; E Sackmann Langmuir, 19 (3), p. 835–841, 2003. @article{Marchi-Artzner:2003, title = {Adhesion of Arg-Gly-Asp (RGD) peptide vesicles onto an integrin surface: Visualization of the segregation of RGD ligands into the adhesion plaques by fluorescence}, author = {V Marchi-Artzner and B Lorz and C Gosse and L Jullien and R Merkel and H Kessler and E Sackmann}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037418070&doi=10.1021%2fla026227k&partnerID=40&md5=a637abfe410c4e6040431b2fcd2d5843}, doi = {10.1021/la026227k}, year = {2003}, date = {2003-01-01}, journal = {Langmuir}, volume = {19}, number = {3}, pages = {835--841}, abstract = {Integrins are adhesion receptors that mediate cell adhesion and play an important function in many biological processes such as morphogenesis and tissue remodeling. These membrane proteins specifically interact with a short tripeptide sequence, RGD (Arg-Gly-Asp), present in numerous extracellular macromolecules. Model systems have been developed in order to understand how membrane adhesion is induced by this specific RGD peptide ligand/integrin recognition system. We have previously shown that RGD giant vesicles selectively adhere to endothelial cells by formation of pinning centers. Nevertheless, the nature of the lipids located in the adhesion contact zone is unknown. One hypothesis is that the lipidic ligands migrate to the contact zone where they are confined after binding to the receptor. To study the possible formation of ligand domains within the vesicle bilayer, we synthesized a fluorescently labeled RGD lipid that can be easily incorporated in giant vesicles. Adhesion of giant RGD vesicles onto an integrin-functionalized surface was followed simultaneously by reflection interference contrast microscopy and fluorescence microscopy. For the first time, it was possible to observe the microsegregation of RGD lipids in the contact zone during adhesion. Additionally, we observed interesting photosensitive properties of the chalcone chromophore that could lead to a new method of analyzing the lipid organization within the membrane during adhesion and to the design of new ligand lipids and vesicle vectors for cell targeting.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Integrins are adhesion receptors that mediate cell adhesion and play an important function in many biological processes such as morphogenesis and tissue remodeling. These membrane proteins specifically interact with a short tripeptide sequence, RGD (Arg-Gly-Asp), present in numerous extracellular macromolecules. Model systems have been developed in order to understand how membrane adhesion is induced by this specific RGD peptide ligand/integrin recognition system. We have previously shown that RGD giant vesicles selectively adhere to endothelial cells by formation of pinning centers. Nevertheless, the nature of the lipids located in the adhesion contact zone is unknown. One hypothesis is that the lipidic ligands migrate to the contact zone where they are confined after binding to the receptor. To study the possible formation of ligand domains within the vesicle bilayer, we synthesized a fluorescently labeled RGD lipid that can be easily incorporated in giant vesicles. Adhesion of giant RGD vesicles onto an integrin-functionalized surface was followed simultaneously by reflection interference contrast microscopy and fluorescence microscopy. For the first time, it was possible to observe the microsegregation of RGD lipids in the contact zone during adhesion. Additionally, we observed interesting photosensitive properties of the chalcone chromophore that could lead to a new method of analyzing the lipid organization within the membrane during adhesion and to the design of new ligand lipids and vesicle vectors for cell targeting. |
Calcium photorelease from a symmetrical donor-acceptor-donor bis-crown-fluoroionophore evidenced by ultrafast absorption spectroscopy Article de journal N Marcotte; P Plaza; D Lavabre; S Fery-Forgues; M M Martin The Journal of Physical Chemistry A, 107 (14), p. 2394-2402, 2003, ISSN: 1089-5639. @article{RN43, title = {Calcium photorelease from a symmetrical donor-acceptor-donor bis-crown-fluoroionophore evidenced by ultrafast absorption spectroscopy}, author = {N Marcotte and P Plaza and D Lavabre and S Fery-Forgues and M M Martin}, url = {<Go to ISI>://000182042400002}, doi = {10.1021/jp027495u}, issn = {1089-5639}, year = {2003}, date = {2003-01-01}, journal = {The Journal of Physical Chemistry A}, volume = {107}, number = {14}, pages = {2394-2402}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Dynamics of full fusion during vesicular exocytotic events: Release of adrenaline by chromaffin cells Article de journal C Amatore; S Arbault; I Bonifas; Y Bouret; M Erard; M Guille ChemPhysChem, 4 (2), p. 147–154, 2003. @article{Amatore:2003d, title = {Dynamics of full fusion during vesicular exocytotic events: Release of adrenaline by chromaffin cells}, author = {C Amatore and S Arbault and I Bonifas and Y Bouret and M Erard and M Guille}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037450055&doi=10.1002%2fcphc.200390024&partnerID=40&md5=fba834474dafda276b2a40772d6c8796}, doi = {10.1002/cphc.200390024}, year = {2003}, date = {2003-01-01}, journal = {ChemPhysChem}, volume = {4}, number = {2}, pages = {147--154}, abstract = {Vesicular exocytosis is important in the communication between cells in complex organisms. It controls the release of specific chemical or biochemical messengers stored in the emitting cell, which elicit a response upon detection by the target cells. Secretion of a messenger molecule (a neurotransmitter) was measured electrochemically, which allowed the quantification of cellular events and the validation of current physicochemical models. This model led us to formulate predictions about the occurrence and kinetics of vesicular exocytotic events based on the physicochemical meaning of its key parameters. These predictions were tested successfully through a series of experiments on chromaffin cells, involving changes of osmotic conditions, presence of trivalent ions and cholesterol-induced structuring of the cell plasmic membrane.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Vesicular exocytosis is important in the communication between cells in complex organisms. It controls the release of specific chemical or biochemical messengers stored in the emitting cell, which elicit a response upon detection by the target cells. Secretion of a messenger molecule (a neurotransmitter) was measured electrochemically, which allowed the quantification of cellular events and the validation of current physicochemical models. This model led us to formulate predictions about the occurrence and kinetics of vesicular exocytotic events based on the physicochemical meaning of its key parameters. These predictions were tested successfully through a series of experiments on chromaffin cells, involving changes of osmotic conditions, presence of trivalent ions and cholesterol-induced structuring of the cell plasmic membrane. |
Electroanalytical investigation of the cobalt-catalyzed electrochemical dimerization of allylic acetates. Role played by iron(II) ions Article de journal O Buriez; E Labbe; J Perichon Journal of Electroanalytical Chemistry, 543 (2), p. 143-151, 2003. @article{RID:0721150706480-19, title = {Electroanalytical investigation of the cobalt-catalyzed electrochemical dimerization of allylic acetates. Role played by iron(II) ions}, author = {O Buriez and E Labbe and J Perichon}, year = {2003}, date = {2003-01-01}, journal = {Journal of Electroanalytical Chemistry}, volume = {543}, number = {2}, pages = {143-151}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Two-Site Molecules as a Road for Engineering Complexity in Chemical Systems Article de journal L Jullien; A Lemarchand; S Charier; O Ruel; J -B Baudin Journal of Physical Chemistry B, 107 (36), p. 9905–9917, 2003. @article{Jullien:2003, title = {Two-Site Molecules as a Road for Engineering Complexity in Chemical Systems}, author = {L Jullien and A Lemarchand and S Charier and O Ruel and J -B Baudin}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0141903432&partnerID=40&md5=9979810858071b93857cd7f74f6d4365}, year = {2003}, date = {2003-01-01}, journal = {Journal of Physical Chemistry B}, volume = {107}, number = {36}, pages = {9905--9917}, abstract = {Molecules that contain two coupled reactive sites are simple chemical systems that may nevertheless already exhibit some complex behaviors when they are subjected to suitable external constraints. This report first proposes a theoretical model and an experimental illustration to demonstrate that the introduction of an auxiliary reactive site on a substrate can lead to local and continuous tuning of the thermodynamic and kinetic properties of a reaction of interest. It is then shown that a similar kinetic scheme that is appropriate for describing the evolution of concentrations in a two-site catalysis exhibits diverse properties when maintaining the system far from equilibrium and varying the order of magnitude of the rate constants: tuning of chemical yield, autocatalysis, and kinetic proofreading are obtained.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Molecules that contain two coupled reactive sites are simple chemical systems that may nevertheless already exhibit some complex behaviors when they are subjected to suitable external constraints. This report first proposes a theoretical model and an experimental illustration to demonstrate that the introduction of an auxiliary reactive site on a substrate can lead to local and continuous tuning of the thermodynamic and kinetic properties of a reaction of interest. It is then shown that a similar kinetic scheme that is appropriate for describing the evolution of concentrations in a two-site catalysis exhibits diverse properties when maintaining the system far from equilibrium and varying the order of magnitude of the rate constants: tuning of chemical yield, autocatalysis, and kinetic proofreading are obtained. |
2002 |
A new analysis of the solvent-induced charge transfer in ADMA by subpicosecond spectroscopy Inproceedings M M Martin; P Plaza; P Changenet; A Siemiarczuk Douhal, A; Santamaría, J (Ed.): Vth International Conference on Femtochemistry, p. 280-288, World Scientific Publishing, 2002, ISBN: 0-444-51656-5. @inproceedings{RN92, title = {A new analysis of the solvent-induced charge transfer in ADMA by subpicosecond spectroscopy}, author = {M M Martin and P Plaza and P Changenet and A Siemiarczuk}, editor = {A Douhal and J Santamar\'{i}a}, doi = {10.1016/b978-044451656-5/50081-5}, isbn = {0-444-51656-5}, year = {2002}, date = {2002-01-01}, booktitle = {Vth International Conference on Femtochemistry}, pages = {280-288}, publisher = {World Scientific Publishing}, series = {Femtochemistry and Femtobiology: Ultrafast Dynamics in Molecular Science}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Excited-state relation dynamics of a PYP chromophore model in solution: Influence of the thioester group Article de journal P Changenet-Barret; A Espagne; N Katsonis; S Charier; J -B Baudin; L Jullien; P Plaza; M M Martin Chemical Physics Letters, 365 (3-4), p. 285–291, 2002. @article{Changenet-Barret:2002, title = {Excited-state relation dynamics of a PYP chromophore model in solution: Influence of the thioester group}, author = {P Changenet-Barret and A Espagne and N Katsonis and S Charier and J -B Baudin and L Jullien and P Plaza and M M Martin}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037109026&doi=10.1016%2fS0009-2614%2802%2901480-X&partnerID=40&md5=5fdfd4c614229bacad91377caee585a1}, doi = {10.1016/S0009-2614(02)01480-X}, year = {2002}, date = {2002-01-01}, journal = {Chemical Physics Letters}, volume = {365}, number = {3-4}, pages = {285--291}, abstract = {Cis-trans photoisomerization of a photoactive yellow protein chromophore model, the deprotonated trans S-phenyl thio-p-hydroxycinnamate, is studied in aqueous solution by subpicosecond transient absorption and gain spectroscopy. The excited-state deactivation is found to involve the formation, in 1.7 ps, of an intermediate state which decays in 2.8 ps. A persistent bleaching signal is observed at longer times indicating that the excited state not only relaxes to the ground state but also partly forms a stable photoproduct, possibly the cis isomer. This behavior is analogous to that of the native photoactive yellow protein. © 2002 Elsevier Science B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Cis-trans photoisomerization of a photoactive yellow protein chromophore model, the deprotonated trans S-phenyl thio-p-hydroxycinnamate, is studied in aqueous solution by subpicosecond transient absorption and gain spectroscopy. The excited-state deactivation is found to involve the formation, in 1.7 ps, of an intermediate state which decays in 2.8 ps. A persistent bleaching signal is observed at longer times indicating that the excited state not only relaxes to the ground state but also partly forms a stable photoproduct, possibly the cis isomer. This behavior is analogous to that of the native photoactive yellow protein. © 2002 Elsevier Science B.V. All rights reserved. |
Hyperpolar multichromophoric nanoassembly for molecular nonlinear optics Inproceedings M Blanchard-Desce; M Ait Amer Meziane; E D Rekaï; J -B Baudin; L Jullien; I Ledoux; J Zyss Proceedings of SPIE - The International Society for Optical Engineering, p. 163–172, 2002. @inproceedings{Blanchard-Desce:2002, title = {Hyperpolar multichromophoric nanoassembly for molecular nonlinear optics}, author = {M Blanchard-Desce and M Ait Amer Meziane and E D Reka\"{i} and J -B Baudin and L Jullien and I Ledoux and J Zyss}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0038754955&doi=10.1117%2f12.452066&partnerID=40&md5=2ab898884653fe6f8f9fc785379b4d94}, doi = {10.1117/12.452066}, year = {2002}, date = {2002-01-01}, booktitle = {Proceedings of SPIE - The International Society for Optical Engineering}, volume = {4798}, pages = {163--172}, abstract = {A multichromophoric nanoassembly was designed by gathering seven push-pull chromophores on a β - cyclodextrin assembling unit via covalent linkers. Such supermolecule provides a valuable model for the investigation of confinement effects on the linear and nonlinear optical properties of push-pull chromophores in the condensed phase. Push-pull chromophores display a significant ground-state dipole, thus promoting dipolar interactions that are expected to influence both the conformation and the optical properties of the multichromophoric assembly. In this perspective, the photophysical and nonlinear optical properties of the mutichromophoric bundle were investigated and compared to those of the monomeric chromophore. The absorption, circular dichroism and fluorescence investigations provide evidence that the push-pull chromophores do not behave as isolated independent chromophores within the multichromophoric assembly. The nanoscale supermolecule is hypsochromically and significantly hypochromically shifted with respect to its monomeric analogue. In addition, the close proximity promotes excitonic coupling, as well as excimer formation phenomena. The nanoscopic assembly also shows a very large dipolar moment (μ = 38 D), and a significant molecular first-order hyperpolarizability, which reveal a spontaneous sheaf-type self-arrangement of the dipolar chromophores within the supermolecule. Such chiral hyperpolar nanoassemblies are promising candidates as model systems for nanophotonics.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } A multichromophoric nanoassembly was designed by gathering seven push-pull chromophores on a β - cyclodextrin assembling unit via covalent linkers. Such supermolecule provides a valuable model for the investigation of confinement effects on the linear and nonlinear optical properties of push-pull chromophores in the condensed phase. Push-pull chromophores display a significant ground-state dipole, thus promoting dipolar interactions that are expected to influence both the conformation and the optical properties of the multichromophoric assembly. In this perspective, the photophysical and nonlinear optical properties of the mutichromophoric bundle were investigated and compared to those of the monomeric chromophore. The absorption, circular dichroism and fluorescence investigations provide evidence that the push-pull chromophores do not behave as isolated independent chromophores within the multichromophoric assembly. The nanoscale supermolecule is hypsochromically and significantly hypochromically shifted with respect to its monomeric analogue. In addition, the close proximity promotes excitonic coupling, as well as excimer formation phenomena. The nanoscopic assembly also shows a very large dipolar moment (μ = 38 D), and a significant molecular first-order hyperpolarizability, which reveal a spontaneous sheaf-type self-arrangement of the dipolar chromophores within the supermolecule. Such chiral hyperpolar nanoassemblies are promising candidates as model systems for nanophotonics. |
Multiple relaxation pathways in push-pull polyenes Article de journal D Laage; P Plaza; M Blanchard-Desce; M M Martin Photochemical and Photobiological Sciences, 1 (7), p. 526–535, 2002. @article{Laage:2002, title = {Multiple relaxation pathways in push-pull polyenes}, author = {D Laage and P Plaza and M Blanchard-Desce and M M Martin}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-17444378861&doi=10.1039%2fb203201p&partnerID=40&md5=98848a0a1dd2e3c4a3b3b4729e644636}, doi = {10.1039/b203201p}, year = {2002}, date = {2002-01-01}, journal = {Photochemical and Photobiological Sciences}, volume = {1}, number = {7}, pages = {526--535}, abstract = {Subpicosecond absorption and gain spectroscopy are used to investigate the excited-state behavior of push-pull polyenes made of a diethylthiobarbituric acid electron-acceptor group and a dibutylaniline electron-donor group linked by a π-conjugated chain. Four polyenes of increasing length, ranging from n = 2 to 5 double bonds, are compared. The relaxation path and relaxation kinetics are studied in dioxane and in cyclohexane, a polar and a nonpolar solvent, respectively. In dioxane, the results provide evidence for the formation of an emissive transient state on an ultrashort time scale (2\textendash3 ps) attributed to a charge transfer (CT) state. The regular shift of the gain peak of this transient state with increase in the chain length (ca. 100 nm per added double bond) indicates that its structure is similar to that of a cyanine, i.e. with a fully conjugated polyenic chain. Its lifetime ranges from a few tens to a few hundreds of picoseconds depending on the chain length. When the number of double bonds increases from n = 2 to 3, the lifetime increases, then decreases continuously for longer chains. In cyclohexane, where the transient CT state is not formed, the decay of the initial excited state follows the same trend when the chain length increases but the lifetimes are shorter than that of the CT state in dioxane. In both solvents, the characterization of long-lived photoproducts by synchronizing two low repetition-rate subpicosecond laser systems demonstrates a change in the relaxation route as the chain length increases. Isomerization occurs for n = 2, whereas intersystem crossing to the triplet state occurs for n = 4. The change in the relaxation channel is observed for n = 3 in both solvents with however a solvent-dependent behavior. In dioxane, relaxation to the triplet state is already observed for n = 3, while an intermediate regime with a relaxation directly to the ground state is observed in cyclohexane. The photophysics of the studied push-pull polyenes is tentatively compared to that of polymethine cyanines and substituted carotenoids. © 2002 The Royal Society of Chemistry and Owner Societies.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Subpicosecond absorption and gain spectroscopy are used to investigate the excited-state behavior of push-pull polyenes made of a diethylthiobarbituric acid electron-acceptor group and a dibutylaniline electron-donor group linked by a π-conjugated chain. Four polyenes of increasing length, ranging from n = 2 to 5 double bonds, are compared. The relaxation path and relaxation kinetics are studied in dioxane and in cyclohexane, a polar and a nonpolar solvent, respectively. In dioxane, the results provide evidence for the formation of an emissive transient state on an ultrashort time scale (2–3 ps) attributed to a charge transfer (CT) state. The regular shift of the gain peak of this transient state with increase in the chain length (ca. 100 nm per added double bond) indicates that its structure is similar to that of a cyanine, i.e. with a fully conjugated polyenic chain. Its lifetime ranges from a few tens to a few hundreds of picoseconds depending on the chain length. When the number of double bonds increases from n = 2 to 3, the lifetime increases, then decreases continuously for longer chains. In cyclohexane, where the transient CT state is not formed, the decay of the initial excited state follows the same trend when the chain length increases but the lifetimes are shorter than that of the CT state in dioxane. In both solvents, the characterization of long-lived photoproducts by synchronizing two low repetition-rate subpicosecond laser systems demonstrates a change in the relaxation route as the chain length increases. Isomerization occurs for n = 2, whereas intersystem crossing to the triplet state occurs for n = 4. The change in the relaxation channel is observed for n = 3 in both solvents with however a solvent-dependent behavior. In dioxane, relaxation to the triplet state is already observed for n = 3, while an intermediate regime with a relaxation directly to the ground state is observed in cyclohexane. The photophysics of the studied push-pull polyenes is tentatively compared to that of polymethine cyanines and substituted carotenoids. © 2002 The Royal Society of Chemistry and Owner Societies. |
Raspberry vesicles Article de journal A -L Bernard; M -A Guedeau-Boudeville; L Jullien; J -M Di Meglio Biochimica et Biophysica Acta - Biomembranes, 1567 (SUPPL.), p. 1–5, 2002. @article{Bernard:2002, title = {Raspberry vesicles}, author = {A -L Bernard and M -A Guedeau-Boudeville and L Jullien and J -M Di Meglio}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037164714&doi=10.1016%2fS0005-2736%2802%2900617-X&partnerID=40&md5=56de717378c694caa9099d109ffa604a}, doi = {10.1016/S0005-2736(02)00617-X}, year = {2002}, date = {2002-01-01}, journal = {Biochimica et Biophysica Acta - Biomembranes}, volume = {1567}, number = {SUPPL.}, pages = {1--5}, abstract = {We present a method to control the osmotic stress of giant unilamellar vesicles (GUV) and we report an original shrinkage mode of the vesicles: the volume reduction is accompanied by the formation of inverted daughter vesicles which gives the shrunk vesicles the appearance of raspberries. We analyze this peculiar shrinkage and we propose some physical origins for the observed phenomena. © 2002 Elsevier Science B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We present a method to control the osmotic stress of giant unilamellar vesicles (GUV) and we report an original shrinkage mode of the vesicles: the volume reduction is accompanied by the formation of inverted daughter vesicles which gives the shrunk vesicles the appearance of raspberries. We analyze this peculiar shrinkage and we propose some physical origins for the observed phenomena. © 2002 Elsevier Science B.V. All rights reserved. |
Reversible bulk photorelease of strontium ion from a crown ether-linked merocyanine Article de journal P Plaza; I Leray; P Changenet-Barret; M M Martin; B Valeur ChemPhysChem, 3 (8), p. 668–674, 2002. @article{Plaza:2002, title = {Reversible bulk photorelease of strontium ion from a crown ether-linked merocyanine}, author = {P Plaza and I Leray and P Changenet-Barret and M M Martin and B Valeur}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037119287&doi=10.1002%2f1439-7641%2820020816%293%3a8%3c668%3a%3aAID-CPHC668%3e3.0.CO%3b2-G&partnerID=40&md5=e2d9cb7c397c5ade6faabcb1eb735f58}, doi = {10.1002/1439-7641(20020816)3:8<668::AID-CPHC668>3.0.CO;2-G}, year = {2002}, date = {2002-01-01}, journal = {ChemPhysChem}, volume = {3}, number = {8}, pages = {668--674}, abstract = {The use of a crown-ether-linked merocyanine, DCM-crown, for producing photoinduced long-lived and reversible concentration jumps of metalcations is reexamined. In this new investigation, the excited-state behavior of DCM-crown complexed with a strontium ion in acetonitrile is found to exhibit the same trends as those previously reported with calcium and lithium ions. However, some new features provide evidence for cation photorelease to the bulk. Subpicosecond transient absorption experiments confirm the initial fast photodisruption of the interaction between the ion and the crown, and the formation of a loose complex after intramolecular charge transfer within the chromophore. Two observed. Firstly, a continuous red shift of the gain spectrum is seen on the subnanosecond scale. It is assigned to the movement of the Sr2+ cation away from the chromophore, partly to the bulk of the solvent and partly towards the formation of an ultraloose complex with oxygen atoms of the crown. Secondly, a free-ligand-like absorption remains after the complete decay of the excited state. This band, which signals a total photorelease of the Sr2+ ion, disappears with a characteristic time of about 110 ns, attributed to the recomplexation of the crown in the ground state of the dye.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The use of a crown-ether-linked merocyanine, DCM-crown, for producing photoinduced long-lived and reversible concentration jumps of metalcations is reexamined. In this new investigation, the excited-state behavior of DCM-crown complexed with a strontium ion in acetonitrile is found to exhibit the same trends as those previously reported with calcium and lithium ions. However, some new features provide evidence for cation photorelease to the bulk. Subpicosecond transient absorption experiments confirm the initial fast photodisruption of the interaction between the ion and the crown, and the formation of a loose complex after intramolecular charge transfer within the chromophore. Two observed. Firstly, a continuous red shift of the gain spectrum is seen on the subnanosecond scale. It is assigned to the movement of the Sr2+ cation away from the chromophore, partly to the bulk of the solvent and partly towards the formation of an ultraloose complex with oxygen atoms of the crown. Secondly, a free-ligand-like absorption remains after the complete decay of the excited state. This band, which signals a total photorelease of the Sr2+ ion, disappears with a characteristic time of about 110 ns, attributed to the recomplexation of the crown in the ground state of the dye. |