Subchromophore interactions in tricyanovinyl-substituted triarylamines - acombined experimental and computational study

The electronic coupling between the phenyl substituents of mono-, bis-, and tris(tricyanovinyl)-substituted triphenylamines (1, 2, 2-OMe and 3) have b een investigated by various methods: the splitting of excited states was ta ken as a measure of the interaction. These splittings can be seen in the op tical absorption spectra; exciton coupling theory was also used to estimate electronic coupling of the excited states; redox potentials gave coupling energies of charged ground state species as well as Hush analysis of interv alence charge-transfer bands (IV-CT), which were observed by UV-Vis-NIR spe ctroelectrochemistry, and finally, the quadratic hyperpolarisability measur ed by hyper-Rayleigh scattering was used to estimate excited state coupling s. The results of these methods were compared to semiempirical AM1 calculat ions and suggest the subchromophore interactions to be weak compared to the band width of the UV-spectra. Nevertheless, the quadratic hyperpolarisabil ity is enhanced in the two-dimensional tris(tricyanovinylphenyl)amine compa red to its one-dimensional analogue.