Photoluminescence, Redox Properties, and Electrogenerated Chemiluminescence of Twisted 9,9′-Bianthryls

To study the dual emission (from locally excited and charge transfer states) of sterically crowded 9,9'-bianthryl (BAHO) and its 10,10'-disubstituted derivatives, namely, 10,10'-dibromo-9,9'-bianthryl (BABR), 10,10'-bis(p-tolylethynyl)-9,9'-bianthryl (BAET), and 10,10'-bis(N,N-diphenyl-4-anilino)-9,9'-bianthryl (BATA) in detail, we probed their photophysical, redox, and electrogenerated chemiluminescence (ECL) responses. Dual emission for all of the molecules was noticed in PL, whereas in ECL only charge transfer emission was observed over a variety of experimental conditions. The PL in nonpolar solvents is significantly influenced by added supporting electrolyte, yielding exclusively charge transfer emission as in ECL. The stability of ECL proved to depend largely on the nature of the substituent, with triarylamine and bromo groups imparting constant ECL intensity over more than 60 cycles.