Remarkable effect of alkynyl substituents on the fluorescence properties of a BN-phenanthrene

Abstract

A series of BN-phenanthrenes with substituents of a diverse nature have been synthesized by palladium-catalyzed cross-coupling reactions of a common chloro-substituted precursor, which was made from readily available materials in only four steps. Evaluation of the photophysical properties of the prepared compounds unveiled an impressive effect of the presence of alkynyl substituents on the fluorescence quantum yield, which improved from 0.01 in the parent compound to up to 0.65 in derivatives containing a triple bond.

Late-stage derivatization of a (B,O)2-doped perylene

“…30 The alkynyl substituents were chosen with the aim of generating appreciably photoluminescent products. [31][32][33][34] Indeed, the yellow compounds 5 and 6 emit blue-green light when irradiated with a UV lamp (λ ex = 366 nm). The corresponding emission bands show a resolved vibrational fine structure in CHCl 3 , with the highest-energy local maxima at 441 (5) and 481 nm (6; Fig.…”