Nanoscale 2018, DOI: 10.1039/C7NR07243K

If the factors controlling the decay in single-molecule electrical conductance G with molecular length L could be understood and controlled, then this would be a significant step forward in the design of high-conductance molecular wires. For a wide variety of molecules conducting by phase coherent tunnelling, conductance G decays with length following the relationship G = AeβL. It is widely accepted that the attenuation coefficient β is determined by the position of the Fermi energy of the electrodes relative to the energy of frontier orbitals of the molecular bridge, whereas the terminal anchor groups which bind to the molecule to the electrodes contribute to the pre-exponential factor A. We examine this premise for several series of molecules which contain a central conjugated moiety (phenyl, viologen or α-terthiophene) connected on either side to alkane chains of varying length, with each end terminated by thiol or thiomethyl anchor groups. In contrast with this expectation, we demonstrate both experimentally and theoretically that additional electronic states located on thiol anchor groups can significantly decrease the value of β, by giving rise to resonances close to EF through coupling to the bridge moiety. This interplay between the gateway states and their coupling to a central conjugated moiety in the molecular bridges creates a new design strategy for realising higher-transmission molecular wires by taking advantage of the electrode–molecule interface properties.

TOC RSC Nano 2018

Des biopiles enzymatiques pour alimenter des circuits électroniques implantables
mardi 10 avril 2018
E. Suraniti, A.G. Mark, J. Roche, H. Richter, A. Kuhn, P. Fischer, N. Mano L’Actualité Chimique 2018, 427-428,127-128 Une micro-source d’énergie intégrée permettrait à des implants biomédicaux miniatures de fonctionner de façon autonome. Les piles ou batteries conventionnelles sont peu adaptées à cette utilisation car difficiles à miniaturiser. Des biopiles enzymatiques peuvent... Read More...
Une façon inhabituelle de briser la symétrie moléculaire: les métaux mesoporeux chiraux
jeudi 22 février 2018
A. Kuhn L’Actualité Chimique 2018, 426,19-24 L’analyse et la synthèse des composés chiraux est d’une importance cruciale dans de nombreux domaines de la société et de la science, y compris la médecine, la biologie, la chimie, la biotechnologie et l’agriculture. Ainsi, il existe un intérêt fondamental dans le développement de nouvelles approches pour la détection et la... Read More...
Gateway state-mediated, long-range tunnelling in molecular wires
jeudi 1 février 2018
S. Sangtarash,  A. Vezzoli,  H. Sadeghi, N. Ferri,  H. M. O'Brien,  I. Grace,  L. Bouffier, S. J. Higgins, R. J. Nichols, C. J. Lambert. Nanoscale 2018, DOI: 10.1039/C7NR07243K If the factors controlling the decay in single-molecule electrical conductance G with molecular length L could be understood and controlled, then this would be a significant step forward...
Tuning Electrochemiluminescence in Multi-Stimuli Responsive Hydrogel Films
lundi 8 janvier 2018
Haidong Li, Silvia Voci, Valérie Ravaine and Neso Sojic J. Phys. Chem. Lett., 2018, 9, 340–345 Luminescent and redox properties of stimuli-responsive hydrogel materials have been modulated by different external stimuli which trigger swelling or collapse of the polymer matrix. There is a very rapid development in the field of such “smart” materials particularly combined with other sensing... Read More...
Bipolar Conducting Polymer Crawlers Based on Triple Symmetry Breaking
vendredi 15 décembre 2017
B. Gupta, B. Goudeau, P. Garrigue, A. Kuhn Adv. Funct. Mater. 2018, 1705825 see also video clip in Zeste de Science Bipolar electrochemistry can be used in different ways to induce motion of an object, for example by generating gas bubbles in an asymmetric way or by a wireless self-regeneration mechanism due to the intrinsic symmetry breaking of this concept. Here a complementary approach is... Read More...