Pronounced Electrochemical Amphotericity of a Fused Donor-Acceptor Compound: A Planar Merge of TTF with a TCNQ-Type Bithienoquinoxaline

The de novo design of a compactly fused π-conjugated molecule that combines a high-lying HOMO with a low-lying LUMO (electrochemical HLG=0.52eV) and a fairly low-lying LUMO+ 1 on the bridging unit, whereby the latter gives rise to strong optical CT transitions, was reported. The study introduced a concept or the annulation of TTF derivatives to acceptor moieties and reported synthetic routes to various fused D-π-A assemblies. The properties displayed is due to the interplay between the π-electronic structure and the well-defined geometrical structure. The HOMO shows large amplitudes on the TTF skeleton, and the LUMO on the TCNQ-type bithienobenzene moiety, both in good agreement with their expected electron donor and acceptor properties. The Raman spectrum and the IR stretching frequency is used to analyses the data. The resulting paramagnetic contributions cause compound to be silent in the HNMR spectrum, and these observations are also manifested in isotropic EPR signals in solution and in the solid state.