Synthesis and characterisation of some donor–acceptor substituted butadienes for second harmonic generation

Abstract

The synthesis and photophysical properties of some donor–acceptor linked butadiene derivatives 6a,b and 7a,b are described. Compounds 6a and 6b show anomalous red-shifted fluorescence bands in polar solvents which can be attributed to the formation of twisted intramolecular charge transfer (TILT) excited states. Powder second harmonic generation (SHG) measurements of these molecules indicated intensities of 0.45 times that of urea for 6a and 7a while negligible intensities are found for 6b and 7b.