Open AccessConformational Study and Chiroptical Properties of Chiral Dimethyl-Ethylenedithio-Tetrathiafulvalene (DM-EDT-TTF)
Author(s) -
Thomas Cauchy,
Flavia Pop,
Jérôme Cuny,
Narcis Avarvari
Publication year - 2018
Publication title -
chimia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.387
H-Index - 55
eISSN - 2673-2424
pISSN - 0009-4293
DOI - 10.2533/chimia.2018.389
Subject(s) - conformational isomerism , enantiopure drug , tetrathiafulvalene , chemistry , crystallography , stereochemistry , computational chemistry , molecule , organic chemistry , enantioselective synthesis , catalysis
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.