Laboratoire P.A.S.T.E.U.R

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Copper-Catalyzed Hydroamination of Allenes: from Mechanistic Understanding to Methodology Development

ACS Catalysis2017, 7 (7), pp 4253–4264

Experimental and theoretical mechanistic studies on the Cu(OTf)2-catalyzed hydroamination reaction of terminal allenes with secondary amines reveal that in-situ generated cationic Cu(I) is the catalytically active species and explain the observed regio- and stereoselectivity for the unbranched E product. Insight about the structure of the relevant transition states allowed the generalization of this methodology to allenamides and N-allenylcarbamates under unprecedentedly mild and functional group tolerant conditions. Chelation effect by the amide oxygen in addition to electronic effects explain the high innate reactivity of this class of substrates.

New avenues for the large-scale harvesting of blue energy

Nature Reviews Chemistry 1, Article number: 0091 (2017)

 

Salinity gradients have been identified as promising clean, renewable and non intermittent sources of energy — so-called blue energy. However, the low efficiency of current harvesting technologies is a major limitation for large-scale viability and is mostly due to the low performances of the membrane processes currently in use. Advances in materials fabrication with dedicated chemical properties can resolve this bottleneck and lead to a new class of membranes for blue-energy conversion. In this Perspective, we briefly present current technologies for the conversion of blue energy, describe their performances and note their limitations. We then discuss new avenues for the development of a new class of membranes, combining considerations in nanoscale fluid dynamics and surface chemistry. Finally, we discuss how new functionalities originating from the exotic behaviour of fluids in the nanoscale regime can further boost energy conversion, making osmotic energy a tangible, clean alternative.

Forced intrusion of water and aqueous solutions in microporous materials: from fundamental thermodynamics to energy storage devices

Chem. Soc. Rev., 8, 2017

 

We review the high pressure forced intrusion studies of water in hydrophobic microporous materials such as zeolites and MOFs, a field of research that has emerged some 15 years ago and is now very active. Many of these studies are aimed at investigating the possibility of using these systems as energy storage devices. A series of all-silica zeolites (zeosil) frameworks were found suitable for reversible energy storage because of their stability with respect to hydrolysis after several water intrusion–extrusion cycles. Several microporous hydrophobic zeolite imidazolate frameworks (ZIFs) also happen to be quite stable and resistant towards hydrolysis and thus seem very promising for energy storage applications. Replacing pure water by electrolyte aqueous solutions enables to increase the stored energy by a factor close to 3, on account of the high pressure shift of the intrusion transition. In addition to the fact that aqueous solutions and microporous silica materials are environmental friendly, these systems are thus becoming increasingly interesting for the design of new energy storage devices.

 

Resonant out-of-phase fluorescence microscopy and remote imaging overcome spectral limitations

Nature Communications 8, 969 (2017)

 

We present speed out-of-phase imaging after optical modulation (OPIOM), which exploits reversible photoswitchable fluorophores as fluorescent labels and combines optimized periodic illumination with phase-sensitive detection to specifically retrieve the label signal. Speed OPIOM can extract the fluorescence emission from a targeted label in the presence of spectrally interfering fluorophores and autofluorescence. Up to four fluorescent proteins exhibiting a similar green fluorescence have been distinguished in cells either sequentially or in parallel. Speed OPIOM is compatible with imaging biological processes in real time in live cells. Finally speed OPIOM is not limited to microscopy but is relevant for remote imaging as well, in particular, under ambient light. Thus, speed OPIOM has proved to enable fast and quantitative live microscopic and remote-multiplexed fluorescence imaging of biological samples while filtering out noise, interfering fluorophores, as well as ambient light.

 

Programmed Self-Assembly of a Biochemical and Magnetic Scaffold to Trigger and Manipulate Microtubule Structures

Scientific REPOrtS | 7: 11344 | 2017

 

Artificial bio-based scaffolds offer broad applications in bioinspired chemistry, nanomedicine, and material science. One current challenge is to understand how the programmed self-assembly of biomolecules at the nanometre level can dictate the emergence of new functional properties at the mesoscopic scale. Here we report a general approach to design genetically encoded protein-based scaffolds with modular biochemical and magnetic functions. By combining chemically induced dimerization strategies and biomineralisation, we engineered ferritin nanocages to nucleate and manipulate microtubule structures upon magnetic actuation. Triggering the self-assembly of engineered ferritins into micrometric scaffolds mimics the function of centrosomes, the microtubule organizing centres of cells, and provides unique magnetic and self-organizing properties. We anticipate that our approach could be transposed to control various biological processes and extend to broader applications in biotechnology or material chemistry.