To determine the effect of donor group geometry on stability and conjugation in donor-acceptor polyenes, four molecules were synthesized and characterized: 5-(4-N,N-dimethylaminophenyl)- (1  ), 5-(5-N-methylindolinyl)- (2  ), 5-(6-N-methyl-2,3,4-trihydroquinolinyl)- (3  ), and 5-(4-julolidinyl)-2,4-pentadienyl-N,N-diethylthiobarbituric acid (4  ). A three-step procedure was used to synthesize each target. Compounds 1 -4  were characterized with UV/vis, IR, fluorescence, 1H NMR, and 13C NMR spectroscopy. UV and 1H NMR solvatochromism in a wide range of solvents was correlated with the ?* polarity scale. NMR coupling constants were related to bond length alternation. Since the acceptor and polyene remained constant in all four molecules, the trends were used to compare donor strength and conjugation. Results were supported with geometry calculations using the B3LYP and HF methods; solvent-dependent electronic transition energies and hyperpolarizabilities were calculated using the ZINDO//B3LYP method.

Effect of pyramidalization at nitrogen in a series of donor-?-acceptor dyes

246th National Meeting (2013)

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