Conformational Equilibria in trans-1,2-Diarylethylenes Manifested in their Emission in Solution. Part VI. Heterocyclic Analogues, their Triplets and Exciplexes

✍ Scribed by T. Wismontski-Knittel; P. K. Das; E. Fischer

• Publisher: John Wiley and Sons
• Year: 1984
• Tongue: German
• Weight: 396 KB
• Volume: 67
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19840670830

✦ Synopsis

Abstract

Solutions of heterocyclic analogues of 2‐styrylnaphthalene (2‐St‐N), with benzo[b]thiophene and benzo[b]furan groups replacing the 2‐naphthyl group, exhibit emission anomalies similar to those reported for 2‐St‐N, the most prominent one being a variation of the emission spectra with the excitation wavelength. The exciplexes formed when emission is quenched by N,N‐dimethylaniline (DMA) show a smaller variation of their emission maxima. Ground‐state rotamers may be responsible for the anomalies. The lifetimes of regular fluorescence in toluene are ≤ 2 ns, and our equipment did not allow to determine whether or not the decay is mono‐exponential. Exciplex lifetimes in toluene are 20‐30 ns. The triplets (λ  500‐520 nm) are characterized by short lifetimes (180‐190 ns) and appear to have substantial contributions from twisted configurations.