The Photo‐dimerization and Excimer Fluorescence of 9‐methyl Anthracene

Abstract

Abstract— Ultra‐violet irradiation of oxygen‐free solutions of 9‐methyI anthracene leads to the formation of both stable dimers and metastable excimers. The fluorescence spectra of concentrated solutions show an excimer emission band. This behaviour is attributed to the partial steric hindrance of dimer formation by the meso‐sub stituent, and it is proposed that the stable dimers and excimers correspond to anti‐parallel and parallel configurations of the two monomers respectively. A consideration of the monomer fluorescence data for anthracene and its meso‐substituted derivatives suggests that steric hindrance similarly reduces the interactions with solvent molecules which lead to internal quenching.

Solid-state photodimerization of 9-methyl-anthracene

“…Structures 9-methyl-anthracene, like similar anthracene derivatives, undergoes a [4 + 4] photodimerization when irradiated with wavelengths λ above 300 nm [2,16,19,20,[22][23][24] both in solution and in the solid state. The reverse process can be induced by heating or by ultraviolet light with λ below 300 nm ( Fig.…”

‘Excimer’ fluorescence - X. Spectral studies of 9-methyl and 9, 10-dimethyl anthracene

“…The room temperature fluorescence spectra of solutions of 9-AL4 in benzene have been previously reported (Birks & Aladekomo 1963) The Stern-Volmer plot of Q m I^-ma gainst c (equation ( 6)) for 9,10 i form at room temperature is shown in the inset of figure 1. Similar plots were obtained for the other solutions.…”

“…In anthracene, meso-substitution has a marked influence on photodimerization (Cherkasov & Vember 1959). 9-methyl anthracene (9 forms stable photo dimers, but with a lower quantum yield than anthracene, and it also forms fluores cent excimers, unlike the parent compound (Birks & Aladekomo 1963). 9,10dimethyl anthracene (9,10 -D M A )d oes not form stable photodimers, but it fo fluorescent excimers.…”

Application of singular value decomposition analysis to time-dependent powder diffraction data of anin-situphotodimerization reaction

“…Global fitting result of 9-MA data showing parameters of equation 2. Aladekomo, 1963;Takegoshi et al, 1998;Ferguson & Mau, 1974). A more detailed discussion about photoisomerization kinetics and the phase growth mechanism of 9-MA has been given by Mabied et al (2012).…”