Synthesis and Properties of a Dicationic π-Extended Dithieno[3,2-c:2′,3′-e]-2,7-diketophosphepin

Methylation of the triazole units of a pi-extended, fluorescent dithieno[3,2-c:2',3'-e]-2,7-diketophosphepin gives rise to a N,N-dimethylated species that shows considerably blue-shifted absorption and emission wavelengths, as well as two reversible and remarkably low reduction steps at E-red = -1.12 and -1.39 V that underline its improved electron-acceptor features. The observed properties are the result of considerably altered electronic as well as structural features triggered by simple methylation of the scaffold.