Conformational Study and Chiroptical Properties of Chiral Dimethyl-Ethylenedithio-Tetrathiafulvalene (DM-EDT-TTF)

Authors

  • Thomas Cauchy Laboratoire Moltech-Anjou, UMR 6200 CNRS- Université d'Angers, UFR Sciences, Bât. K 2 Bd. Lavoisier, 49045 Angers, France. thomas.cauchy@univ-angers.fr
  • Flavia Pop Laboratoire Moltech-Anjou, UMR 6200 CNRS-Université d'Angers, UFR Sciences, Bât. K 2 Bd. Lavoisier, 49045 Angers, France
  • Jérôme Cuny Laboratoire de Chimie et Physique Quantiques LCPQ/IRSAMC Université de Toulouse (UPS) and CNRS 118 Route de Narbonne, F-31062 Toulouse, France
  • Narcis Avarvari Laboratoire Moltech-Anjou, UMR 6200 CNRS-Université d'Angers, UFR Sciences, Bât. K 2 Bd. Lavoisier, 49045 Angers, France. narcis.avarvari@univ-angers.fr

DOI:

https://doi.org/10.2533/chimia.2018.389

Keywords:

Chirality, Circular dichroism, Dft calculations, Free energy surface analysis, Tetrathiafulvalenes

Abstract

The enantiopure dimethyl-ethylenedithio-tetrathiafulvalene (DM-EDT-TTF) donor exists as biaxial (ax, ax) and biequatorial (eq, eq) conformers in equilibrium. DFT calculations combined with free energy surface (FES) analysis establish that the (ax, ax) form is more stable by ?0.7 kcal·mol–1 than the (eq, eq) one and that the inter-conversion process involves a sequential conformational change through a boat type (ax, eq) conformer with an activation energy of ?3 kcal.mol–1. TD-DFT calculations show similar, but opposite in sign, CD bands for the two conformers. A Boltzmann type average of the two CD curves, corresponding to a ratio of three (ax, ax) for one (eq, eq) conformers in equilibrium in solution, provides an excellent agreement with the experimental curve.

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Published

2018-06-27

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