The production of light upon the electron transfer reaction of electrogenerated radical ions of tetraarylpyrroles [aryl = anisyl (TAP), phenyl (TPP), tolyl (TTP), p-chloro-phenyl (TCPP)], tetraphenylfuran (TPF), and tetraphenylthiophene (TPT) in systems containing these compounds alone in acetonitrile solutions or in mixed systems containing naphthalene, 2,5-diphenyl-l,3,4-oxadiazole, benzophenone, and tri-p-tolylamine is reported. Emission which corresponds to the fluorescence of the TAP, TPP, TTP, TPF, and TPT, as well as longer wavelength emission attributed to exciplex emission for some mixed systems, is observed. The singlet and triplet level energies of the compounds of interest are estimated and their cyclic voltammetric behavior described briefly.The usual basic requirements for a system which produces light upon the electron transfer reaction of + electrogenerated species, e.g., A-and D" (electrogenerated chemiluminescence or ECL), include the formation of stable radical ions, the fluorescence of at least one of the parent species (A and D), and sufficient free energy release in the A-/D*" reaction to form an M excited state. Moreover, efficient ECL systems, such as those involving 9,10-diphenylanthracene and rubrene, involve bulky molecules in which steric effects appear to hinder formation of complexes between the reactant species. Previous studies (1-6) have shown that tetra-aryl substituted five-member ring compounds (pyrroles, furans, and thiophenes) X = NH Ar~Ar
