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.