Excimer Fluorescence of 1,2-Di(9-anthryl)ethane, 1,3-Di(9-anthryl)propane, and 9,9′-Bianthryl at High Pressures

Abstract

Fluorescence spectra of 1,2-di(9-anthryl)ethane (1), 1,3-di(9-anthryl)propane (2), and 9,9′-bianthryl (3) have been studied at high pressures up to 50 kbar both in crystalline state and in PMMA matrix. In the case of 1 and 2 in crystalline state, the excimer emissions appear reversibly at high pressures accompanied by the reversible red shifts. While in PMMA the fluorescence spectra assigned as locally excited state are observed, whose peak shifts are quite analogous to that of anthracene in the same matrix. As for 3, a new band also appears at high pressure which is similar to the intramolecular charge-transfer band. Possible interpretations of the pressure effects are discussed.

Unimolecular photochemistry of anthracenes

“…311 In line with earlier observations on a series of a,«-dipyrenyl alkanes, quantum yields of excimer luminescence vary with the length of the alkane chain.324 For l,2-di(9-anthryl)ethane and l,3-di(9-anthryl)propane, the question of excimer formation continues to be of interest, although excimer emission has been detectable only under special environmental conditions. [326][327][328][329][330][331] In a recent emission spectroscopic investigation of a,<i)-di(9-anthryl)alkanes of varying chain length (C3, C5, C7, C10, C12, C14, and Cjg), picosecond time-resolved measurements have revealed intramolecular "excitation hopping" for photoexcited l,7-di(9-anthryl)heptane and its higher homologues. 332 It should be pointed out that the quantum yields of disappearance of a,«-di(9-anthryl)alkanes are not to be considered quantum yields of isomerization, because intermolecular cycloaddition may become an important competing reaction if intramolecular cycloaddition proceeds with low quantum yield.…”