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2019-09-27

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Si us plau utilitzeu sempre aquest identificador per citar o enllaçar aquest document: https://hdl.handle.net/2445/184291

Electronic engineering of a tetrathiafulvalene charge-transfer salt via reduced symmetry induced by combined substituents

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https://doi.org/10.1039/C9CP04320A

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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.

Matèries

Difracció de raigs X, Estructura electrònica

Matèries (anglès)

X-rays diffraction, Electronic structure

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Articles publicats en revistes (Ciència dels Materials i Química Física)
Articles publicats en revistes (Institut de Química Teòrica i Computacional (IQTCUB))

Citació

KIYOTA, Y., JEON, I.-r., JEANNIN, O., BEAU, M., KAWAMOTO, T., ALEMANY I CAHNER, Pere, CANADELL, Enric, MORI, T., FOURMIGUÉ, M.. Electronic engineering of a tetrathiafulvalene charge-transfer salt via reduced symmetry induced by combined substituents. _Physical Chemistry Chemical Physics_. 2019. Vol. 40, núm. 22639-22646. [consulta: 25 de febrer de 2026]. ISSN: 1463-9076. [Disponible a: https://hdl.handle.net/2445/184291]

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