Spectroscopic investigation of a brightly colored psittacofulvin pigment from parrot feathers.

Octadecaoctaenal is a psittacofulvin pigment associated with the bright red coloration of parrots. It consists of a linear polyene chain terminated by an aldehyde group and therefore provides an opportunity to examine the fundamental factors controlling the excited state ordering and dynamics of polyenals. Steady-state and ultrafast time-resolved spectroscopy were performed on octadecaoctaenal and a derivative in which the aldehyde group was converted to a methylenehydroxyl group. It was found that for octadecaoctaenal, solvent proticity was more important than polarity in determining its excited state lifetime. Theoretical computations were carried out to reveal the origin of the effect. [ABSTRACT FROM AUTHOR]