Two-Photon Absorption and Optical Limiting Properties of a New 9-Branched Fluorene Derivative

A new trisubstituted fluorene derivative, 4,4’-{{9-{4-(diethylamino)benzylidene}-9H-fluorene-2,7-diyl}di-2,1- ethenediyl}bis(N,N-diphenyl)benzeneamine (1), with electron-donating N,N-diphenyl-4-vinylaniline group at the 2- and 7-positions, and a N,N-diethyl-4-vinylaniline group as a branch at the 9-position, has been synthesized by a route involving Heck reaction. The photophysical properties of this compound in six different solvents were examined in detail and compared with its non-branched analogue to establish structure-properties relationships. The two-photon absorption coefficient BETA of the sample was found to be 1.32 × 10–2 cm GW–1, determined by a direct nonlinear optical transmission (NLT) method, when pumped by Ti-sapphire laser at 775 nm, which indicates its potential as an optical limiting material.