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Sauvage J.-P.,CNRS Institute of Science and Supramolecular Engineering | Amabilino D.B.,Campus Universitari Of Bellaterra
Topics in Current Chemistry | Year: 2012

What makes a given object look beautiful to the observer, be it in the macroscopic world or at the molecular level? This very general question will be briefly addressed at the beginning of this essay, in relation to contemporary molecular chemistry and biology, leading to the general statement that, most of the time, beauty is tightly connected to function as well as to the cultural background of the observer. The main topic of the present article will be that of topologically non-trivial molecules or molecular ensembles and the fascination that such species have exerted on molecular or solid state chemists. Molecules with a graph identical to Kuratowski's K 5 or K 3,3 graphs are indeed highly attractive from an aesthetical viewpoint, but perhaps even more fascinating and beautiful are molecular knots. A general discussion will be devoted to these compounds, which are still considered as exotic species because of the very limited number of efficient synthetic strategies leading to their preparation. Particularly efficient are templated approaches based either on transition metals such as copper(I) or on organic groups able to form hydrogen bonds or acceptor-donor stacks. A particularly noteworthy property of knots, and in particular of the trefoil knot, is their topological chirality. The isolation of both enantiomers of the trefoil knot (3 1) could be achieved and showed that such species have fascinating chiroptical properties. Finally, various routes to more complex and beautiful knots than the trefoil knot, which is the simplest non-trivial knot, will be discussed in line with the remarkable ability of transition metals to gather and orient in a very precise fashion several organic components in their coordination spheres, thus leading to synthetic precursors displaying geometries which are perfectly well adapted to the preparation of the desired knots or links. © 2011 Springer-Verlag Berlin Heidelberg. Source

Pop F.,CNRS Angers Institute of Molecular Science and Technology | Pop F.,CNRS French National High Magnetic Field Laboratory | Auban-Senzier P.,University Paris - Sud | Canadell E.,Campus Universitari Of Bellaterra | And 2 more authors.
Nature Communications | Year: 2014

So far, no effect of chirality on the electrical properties of bulk chiral conductors has been observed. Introduction of chiral information in tetrathiafulvalene precursors represents a powerful strategy towards the preparation of crystalline materials in which the combination of chirality and conducting properties might allow the observation of the electrical magnetochiral anisotropy effect. Here we report the synthesis by electrocrystallization of both enantiomers of a bulk chiral organic conductor based on an enantiopure tetrathiafulvalene derivative. The enantiomeric salts crystallize in enantiomorphic hexagonal space groups. Single crystal resistivity measurements show metallic behaviour for the enantiopure salts down to 40 K, in agreement with band structure calculations. We describe here the first experimental evidence of electrical magnetochiral anisotropy in these crystals, confirming the chiral character of charge transport in our molecular materials. © 2014 Macmillan Publishers Limited. All rights reserved. Source

Canevet D.,CNRS Angers Institute of Molecular Science and Technology | Perez Del Pino A.,Campus Universitari Of Bellaterra | Amabilino D.B.,Campus Universitari Of Bellaterra | Salle M.,CNRS Angers Institute of Molecular Science and Technology
Journal of Materials Chemistry | Year: 2011

The control of the morphology of nanostructures formed from a single component molecular material incorporating electron accepting and donating moieties is shown, from both solution and gel states. The compound comprises one tetrathiafulvalene (TTF) and two pyrene units which act as the π-electron rich and deficient units, respectively, and which are united by amide-containing linkers whose additional role is to aide aggregation by hydrogen bonding. This role was demonstrated by IR and NMR spectroscopy. The gels were deposited onto surfaces and the solvent allowed to evaporate, leaving films formed by meshes of fibres with different morphologies in accord with the different solvents used to form the materials. Doping of these xerogels with iodine vapour afforded conducting films whose characteristics were probed with current sensing atomic force microscopy (CS-AFM), providing current maps and I-V curves which show how dramatically the processing solvent can influence the electronic properties of these xerogel-derived materials. © 2011 The Royal Society of Chemistry. Source

Gonzalez-Campo A.,Campus Universitari Of Bellaterra | Amabilino D.B.,Campus Universitari Of Bellaterra
Topics in Current Chemistry | Year: 2013

Interfaces are a most important environment in natural and synthetic chemistries for a wide variety of processes, such as catalysis, recognition, separation, and so on. Naturally occurring systems have evolved to one handedness and the study of interfaces where biomolecules are located is a potentially revealing pursuit with regard to understanding the reasons and importance of stereochemistry in these environments. Equally, the spontaneous resolution of achiral and chiral compounds at interfaces could lead to explanations regarding the emergence of single handedness in proteins and sugars. Also, the attachment of biomolecules to surfaces leads to systems capable of stereoselective processes which may be useful for the applications mentioned above. The review covers systems ranging from small biomolecules studied under ultrapure conditions in vacuum to protein adsorption to surfaces in solution, and the techniques that can be used to study them. © Springer-Verlag Berlin Heidelberg 2012. Source

Canevet D.,CNRS Angers Institute of Molecular Science and Technology | Perez Del Pino A.,Campus Universitari Of Bellaterra | Amabilino D.B.,Campus Universitari Of Bellaterra | Salle M.,CNRS Angers Institute of Molecular Science and Technology
Nanoscale | Year: 2011

An organogelator with two distinct π-functional units is able to incorporate carbon nanotubes into its mesh of fibres in the gel state. The morphology of the material derived from this nanocomposite after evaporation of the solvent is a complex mesh of fibres which is clearly different from the pure gelator. This feature indicates a role of the nanotubes in assisting the formation of a fibre structure in the gel thanks to their interaction with the pyrene units in the organogelator. The nanocomposite conducts electricity once the p-type gelator is doped with iodine vapour. The change in morphology caused by the carbon material increases the conductivity of the material compared with the purely organic conducting system. It is remarkable that this improvement in the physical property is caused by an extremely small proportion of the carbon material (only present at a ratio of 0.1% w/w). The practically unique properties of TTF unit allow measurements with both doped and undoped materials with conducting atomic force microscopy which have demonstrated that the carbon nanotubes are not directly responsible for the increased conductivity. © 2011 The Royal Society of Chemistry. Source

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