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Solid‐State Photochromic Behavior and Thermal Bleaching Kinetics of Two Novel Pyrazolone Phenylsemicarbazones
Author(s) -
Abdurehman Samat,
Liu Lang,
Jia Dianzeng,
Hu Jianping,
Guo Jixi,
Xie Xiaolin
Publication year - 2011
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201001070
Subject(s) - photochromism , kinetics , chemistry , fourier transform infrared spectroscopy , pyrazolone , spectroscopy , fluorescence , photochemistry , activation energy , fluorescence spectroscopy , analytical chemistry (journal) , chemical engineering , organic chemistry , optics , physics , quantum mechanics , engineering
Two novel photochromic compounds, 1,3‐diphenyl‐4‐benzal‐5‐hydroxypyrazole 4‐phenylsemicarbazone ( 1 a ) and 1,3‐diphenyl‐4‐(4‐nitrobenzal)‐5‐hydroxypyrazole 4‐phenylsemicarbazone ( 2 a ), are synthesized and characterized by elemental analysis, mass spectrometry, FTIR spectroscopy, and 1 H NMR spectroscopy. Their properties, including photochromic behavior, fluorescence properties, and thermal bleaching kinetics, are investigated. The results show that the two compounds exhibit improved photochromic performance in coloration and thermal bleaching rates, excellent photostability, high fatigue resistance, and reversible fluorescence switching properties in the solid state in comparison to reported pyrazolone thiosemicarbazones. The thermal bleaching process obeys first‐order kinetics. Bleaching of powders at 130 °C is completed within 90 s for 1 b (the colored isomer of 1 a ) and 150 s for 2 b (the colored isomer of 2 a ). The activation energy for the thermal bleaching process is determined to be 69 and 95 kJ mol −1 , with frequency factors of 9.5×10 7 and 9.4×10 10 s −1 for 1 b and 2 b , respectively.