Electrogenerated Chemiluminescence of trans‐Stilbene Derivatives

Abstract

Fluorescence maxima, fluorescence quantum yields, electrode potentials, and electrogene~ated chemiluminescence (ecl) of 16 t-stilbene derivatives such as substituted indenes and dihydronaphthalenes (DHNP) are reported. Both indenes and DHNP's were found to have greatly enhanced fluorescence quantum yields in comparison to t-stilbene. Twelve single systems of 16 compounds gave ecl mostly attributed to the singlet excited state. With tri-ptolylamine (TPTA) added as a source of cation radical, most of the systems produced ecl having shorter wavelength emission corresponding to the singlet excited state of the t-stilbene derivatives and longer wavelength emission attributed to the exciplex. The ecl intensities with respect to the possible applications are discussed.Eleetrogenerated chemiluminescence (ecl) is a process where the electrochemically generated radical species, usually cation and anion radicals, annihilate to give an excited state molecule, which subsequently emits light (1, 2). Due to its uniqueness in exciting molecules, several possible applications have been sug-H\ gested and discussed (3-9). In our continuing effort c=c /-* Electrochemical Society Active Member.

Excimer and intramolecular charge transfer chemiluminescence from electrogenerated ion radicals of donor-acceptor stilbenoids

“…Thus radical cations for these donoracceptor stilbenoid compounds are more stable than their anion radicals. As compared with unsubstituted trans-stilbene 1, 17 the substituted stilbenoids 2-9 show less reversibility for both the reduction and oxidation peaks. This is probably due to the localization of charge and non-planarity for these radical 18 Electron donating groups will raise the energy levels of both the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) whilst electron withdrawing groups will lower the energy levels of both the HOMO and the LUMO.…”

“…For trans-stilbene (1), it was reported that no ECL was observed. 17 If the relative stability of the radical ions is different, the sequence of applying anodic and cathodic currents is significant in obtaining the optimum intensity of ECL. For compound 4 the best ECL is obtained by sequential anodic-cathodic steppings.…”

The Scientific Legacy of Su-Moon Park: a Personal View

“…15 Park was starting a project on this topic, and I was keen to work on it, but another student, James Wilson, selected it first. 16,17 Little did I know at that time that I would have a chance to work with Professor Fujishima in Japan, although on other topics.…”