Neutral and cationic pyridylbutadienes: solvatochromism and fluorescence response with sodium cholate.

Neutral and cationic diarylbutadienes with pyridine and pyridinium groups as electron acceptors with dimethylamine and diphenylamine as electron donors were synthesized. The absorption and emission properties of these dienes were investigated in homogeneous organic solvents and in sodium cholate media. In strongly polar solvents, both neutral and cationic fluorophores exhibit a bathochromic shift of emission characteristics of intramolecular charge transfer (ICT) excited states.

Photoisomerization of Trans Ortho-, Meta-, Para-Nitro Diarylbutadienes: A Case of Regioselectivity.

A series of ortho-, meta- and para-substituted trans-nitro aryl (phenyl and pyridyl) butadienes have been synthesized and characterized. The effect of substitution and positional selectivity on their fluorescence and photoisomerization were systematically investigated. Among all dienes, meta- and para-nitro phenyl-substituted derivatives exhibit remarkable solvatochromic emission shifts due to intramolecular charge transfer.