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English

Mono- and Bis(tetrathiafulvalene)-1,3,5-Triazines as Covalently Linked Donor-Acceptor Systems: Structural, Spectroscopic, and Theoretical Investigations

Published inChemistry, vol. 15, no. 2, p. 380-387
Publication date2009
Abstract

Reaction of 2,4,6-trichloro-1,3,5-triazine with lithiated tetrathiafulvalene (TTF) in stoichiometric conditions, followed by treatment with sodium methanolate, provides mono- and bis(TTF)-triazines as new covalently linked (multi)donor-acceptor systems. Single-crystal X-ray analyses reveal planar structures for both compounds, with formation of peculiar segregated donor and acceptor stacks for the mono(TTF)-triazine compound, while mixed TTF-triazine stacks establish in the case of the bis(TTF) derivative. Cyclic voltammetry measurements show reversible oxidation of the TTF units, at rather low potential, with no splitting of the oxidation waves in the case of the dimeric TTF, whereas irreversible reduction of the triazine core is observed. Intramolecular charge transfer is experimentally evidenced through solution electronic absorption spectroscopy. Time-dependent DFT calculations allow the assignment of the charge transfer band to singlet transitions from the HOMO of the donor(s) to the LUMO of the acceptor. Solution EPR measurements correlated with theoretical calculations were performed in order to characterize the oxidized species. In both cases the spectra show very stable radical species and contain a triplet of doublet pattern, in agreement with the coupling of the unpaired electron with the three TTF protons. The dication of the bis(TTF)-triazine is paramagnetic, but no spin-spin exchange interaction could be detected.

Keywords
  • Charge transfer
  • Donor-acceptor systems
  • EPR spectroscopy
  • Nitrogen heterocycles
  • Structure elucidation
  • Tetrathiafulvalenes
Research group
Citation (ISO format)
RIOBÉ, François et al. Mono- and Bis(tetrathiafulvalene)-1,3,5-Triazines as Covalently Linked Donor-Acceptor Systems: Structural, Spectroscopic, and Theoretical Investigations. In: Chemistry, 2009, vol. 15, n° 2, p. 380–387. doi: 10.1002/chem.200801851
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ISSN of the journal0947-6539
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