Crystal structure and spectroscopic study on photochromism of 1-phenyl-3-methyl-4-benzal-5-pyrazolone 4-ethylthiosemicarbazone

The crystal structure of the title compound 1-phenyl-3-methyl-4-benzal-5-pyrazol one 4-ethyl thiosemicarbazone (PMBP-ETSC), as determined by X-ray analysis, shows that the pyrazolone moiety stabilizes in the keto form and the molecule is found to be in three-dimensional arrangement in the unit cell linked by intermolecular hydrogen bonds. The important bands in IR spectra, as well as the main signals of the H-1 NMR spectra are assigned. Meanwhile, the steady state, time-dependent fluorescence emission spectroscopy, the powder UV-Vis reflection spectroscopy of the solid product and theoretical chemistry calculations of reaction rate constant are also studied, the results of which show that PMBP-ETSC can perform photochromism. (C) 2004 Elsevier B.V. All rights reserved.