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Title: Electronic engineering of a tetrathiafulvalene charge-transfer salt via reduced symmetry induced by combined substituents
Author: Kiyota, Y.
Jeon, I.-R.
Jeannin, O.
Beau, M.
Kawamoto, T.
Alemany i Cahner, Pere
Canadell, Enric, 1950-
Mori, T.
Fourmigué, M.
Keywords: Difracció de raigs X
Estructura electrònica
X-rays diffraction
Electronic structure
Issue Date: 27-Sep-2019
Publisher: Royal Society of Chemistry
Abstract: A 1 : 1 metallic charge-transfer salt is obtained by cosublimation of (Z,E)-(SMe)2Me2TTF and TCNQ. X-ray diffraction studies confirm the formation of segregated stacks comprising donor and acceptor molecules in [(E)-(SMe)2Me2TTF](TCNQ). The crystal packing features lateral S􏰒􏰒􏰒S interactions between TTF stacks, which is in sharp contrast to that in (TTF)(TCNQ). Structural analysis and theoretical studies afford a partial charge-transfer (r E 0.52), leading to a system with the electronic structure close to quarter-filled. Resistivity measurements reveal that this material behaves as a metal down to 56 K and 22 K at 1 bar and 14.9 kbar, respectively. The thermopower is negative in the metallic regime, indicating the dominant role of the acceptor stacks for the observed conducting behavior. Analysis of single- crystal EPR spectra shows the remaining spin susceptibility at 4.3 K, suggesting the importance of the Hubbard U correction. These results highlight the judicious engineering of electronic and geometrical effects on the TTF core; the combined use of methyl and thiomethyl groups has decreased the TCNQ bandwidth while maintaining the segregated stacks, converting the metal to insulator (M-I) transition to more 4kF like. In addition, the enhanced S􏰒􏰒􏰒S contacts between the TTF stacks lead to more rapidly decreasing M-I transition temperature under various pressures.
Note: Versió postprint del document publicat a:
It is part of: Physical Chemistry Chemical Physics, 2019, vol. 40, p. 22639-22646
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ISSN: 1463-9076
Appears in Collections:Articles publicats en revistes (Ciència dels Materials i Química Física)
Articles publicats en revistes (Institut de Química Teòrica i Computacional (IQTCUB))

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