Dual Signaling System with an Extended-Tetrathiafulvalene–Phenanthroline Dyad Acting as an Electrooptical Cation Chemosensor

An efficient synthesis of unprecedented fused extended-tetrathiafulvalene–dipyridoquinoxaline (exTTF-dpq) dyad is described through the Horner–Wardsworth–Emmons olefination methodology from the dipyrido[3,2-a:2′,3′-c]-benzo[3,4]phenazine-11,16-quinone (NqPhen) ligand starting material. This exTTF-dpq dyad is demonstrated to act as a dual redox and colorimetric sensor for cations exploiting the proximity between the redox tetrathiafulvalene and the optical phenanthroline detecting sites. Its ability for sensing cations from the d-group metal transitions (Fe2+, Ni2+, and Zn2+) and also with varied cations such as Ca2+ and Pb2+ is presented.