Computational and spectroscopic studies concerning the solvatochromic behavior of 1,3-disubstituted azulenes

Estimates of excited-state dipole moments for various 1,3-disubstituted azulenes possessing electron-withdrawing substituents, using the CIS/6-31+G(d,p) model, reveal that unlike azulene, the excited-state dipole moments are generally in the same direction as, although smaller in magnitude than, their ground-state counterparts. This gives rise to hypsochromic shifts in the UV-visible spectrum of these dipolar indicator molecules as solvent polarity is increased. Furthermore, B3LYP density functional calculations on several 1,3-diacylazulenes indicate that the s-cis conformation is preferred over s-trans. (C) 2006 Wiley Periodicals, Inc.