Thiophene-Functionalized TTF π-Electron Donors as Potential Precursors to Conducting Polymers and Organic Metals:  Synthesis, Properties, Structure, and Electropolymerization Studies

Abstract

The synthesis and physical properties of a series of novel thiophene-substituted TTF electron donors (6a-d) are described. The cyclic voltammograms of 6a-d exhibited two reversible one-electron redox waves, characteristic of TTF derivatives. Electropolymerization studies on compound 6a in nitrobenzene indicate that no polymer formed on the working electrode, but a blue-colored intermediate was observed diffusing away from the electrode. In addition, the single-crystal X-ray structure of compound 6d indicates that the central five-membered C(3)S(2) rings are buckled and the ethylenedithiolo fragment adopts a twisted chair conformation. The pendant thiophene moieties are highly flexible, and short intermolecular interactions of 3.49 Å (S.S) and 3.45 Å (S.C) exist in the unit cell, resulting in the formation of a chain structure along the c-axis.

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“…This counter-intuitive behavior can be assigned to the fact that when the thiophene ring is fused to 1,3-dithiole, this latter doesn’t behave as a donor but as an acceptor, reducing the electron donating ability of the 1,3-dithiole moiety. A similar behavior was previously reported for TTF derivatives [78,79]. The most red-shifted ICT was detected for 131 , bearing 21 as the acceptor and the ICT was detected at 596 nm (see Table 6).…”

Nickel dithiolenes containing pendant thiophene units: precursors to dithiolene–polythiophene hybrid materials

“…In this context, some of us developed over recent years TTF derivatives bearing thiophene moieties and showed that electrochemical polymerisation of these thiophene units could be achieved. [9][10][11] This demonstrated the possibility of preparing polythiophenes bearing TTF side groups with the potential to develop conducting materials combining the processability of the conducting polymer with some of the structural regularity that can be achieved in TTF-based conductors. The TTF may alter the conductivity properties of the resulting hybrid material either by providing an alternative conductivity pathway or by modifying the properties of the polymer by cooperative electronic effects.…”

Electropolymerisable dithiolene complexes

“…Charlton et al described the synthesis of two 4,5-dithiophen-x-yl [1,3]dithiol-2-ones, the 2-thienyl [20,21] and 3thienyl [13], via a benzoin condensation reaction of the appropriate starting thiophenecarboxaldehyde. Thehydroxy ketones could then be converted in high yield under mild conditions to the -chloride by reaction with CCl 4 and PPh 3 .…”