Structure-property relationships in conjugated donor-acceptor systems functionalized with tetrathiafulvalene

The properties of two donor-acceptor compounds tetrathiafulvalene-acenaphtho[1,2-b]quinoxaline (1) and tetrathiafulvalene-3-nitro-acenaphtho[1,2-b]quinoxaline (2) have been investigated by solution-state studies (electrochemistry, absorption, self-assembly) and theoretical calculations (DFT, TD-DFT). The electrochemical studies indicate the nitro-substituted effect on their redox properties is negligible. Both compounds show effective intramolecular charge transfer (ICT) transitions in the UV-Visible range in solution. Compared with compound 1, compound 2 has a bathochromic shift in the absorption spectra, the lambda(max-ICT) has been extended from 20 800 cm(-1) to 19 700 cm(-1) (480 nm to 507 nm). In addition, when the nitro group is employed, the self-assembly characteristics of the two compounds are substantially changed from ribbon-like nanostructures to root-like nanostructures. Density functional theory (DFT) calculations provide insights into their molecular geometries, electronic structures, and physico-chemical properties.