Imidazole-Annulated Tetrathiafulvalenes Exhibiting pH-Tuneable Intramolecular Charge Transfer and Redox Properties

CT or not CT: Three imidazole–annulated TTF derivatives 1–3 have been prepared and fully characterized. The influence of the TTF unit on the pKa values of the acceptor units as determined by photometric titration has been discussed. The results reported here are part of an initial exploratory study to generate a range of well–defined coordination networks. In order to study the electronic interactions in donor–acceptor ensembles as a function of pH, an efficient synthetic route to three imidazole–annulated tetrathiafulvalene (TTF) derivatives 1–3 is reported. Their electronic absorption spectra, in view of photoinduced intramolecular charge transfer, and their electrochemical behavior were investigated, and pKa values for the two protonation processes on the acceptor unit were determined in organic solvents by photometric titration. The influence of the TTF moiety on these values is discussed.