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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Conservation of structural arrangements and 3 : 1 stoichiometry in a series of crystalline conductors of TMTTF, TMTSF, BEDT-TTF, and chiral DM-EDT-TTF with the oxo-bis[pentafluorotantalate(v)] dianion.
Chem Sci
August 2020
MOLTECH-Anjou, UMR 6200, CNRS, UNIV Angers 2 bd Lavoisier 49045 ANGERS Cedex France
The occurrence of isostructural conducting radical cation salts of diversely substituted tetrathiafulvalene (TTF) precursors with the same anion is most often limited to very similar derivatives such as tetramethyl-tetrathiafulvalene (TMTTF) and tetramethyl-tetraselenafulvalene (TMTSF). Here we show that the use of the oxo-bis[pentafluorotantalate(v)] dianion [TaFO] affords upon electrocrystallization of TMTTF, TMTSF, bis(ethylenedithio)-tetrathiafulvalene (BEDT-TTF), racemic dimethyl-ethylenedithio-tetrathiafulvalene (()-DM-EDT-TTF), and enantiopure (,)-DM-EDT-TTF a series of mixed valence crystalline radical cation salts with the same 3 : 1 stoichiometry. The donor layers show similar features in the five materials, such as alternation of trimeric units within stacks which arrange in parallel columns of β-type.
View Article and Find Full Text PDFConformational Study and Chiroptical Properties of Chiral Dimethyl-Ethylenedithio-Tetrathiafulvalene (DM-EDT-TTF).
Chimia (Aarau)
June 2018
Laboratoire Moltech-Anjou, UMR 6200 CNRS-Université d'Angers, UFR Sciences, Bât. K 2 Bd. Lavoisier, 49045 Angers, France;, Email:
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.
View Article and Find Full Text PDFChirality driven metallic versus semiconducting behavior in a complete series of radical cation salts based on dimethyl-ethylenedithio-tetrathiafulvalene (DM-EDT-TTF).
J Am Chem Soc
November 2013
Laboratoire MOLTECH-Anjou, UMR 6200, UFR Sciences, Université d'Angers, CNRS , Bâtiment K, 2 Bd. Lavoisier, 49045 Angers, France.
Enantiopure (S,S) and (R,R) dimethyl-ethylenedithio-tetrathiafulvalene (DM-EDT-TTF) 1 donors are synthesized by cross coupling followed by decarboxylation reactions. In the solid state the methyl groups are arranged in axial positions within sofa-type conformation for the six-membered rings. Crystalline radical cation salts formulated as [(S,S)-1]2PF6, [(R,R)-1]2PF6, and [(rac)-1]2PF6 are obtained by electrocrystallization.
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