Solid‐State Photochromic Behavior and Thermal Bleaching Kinetics of Two Novel Pyrazolone Phenylsemicarbazones |
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| Authors: | Samat Abdurehman Dr. Lang Liu Prof. Dianzeng Jia Jianping Hu Dr. Jixi Guo Prof. Xiaolin Xie |
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| Affiliation: | 1. Key Laboratory of Material and Technology for Clean Energy, Ministry of Education, Key Laboratory of Advanced, Functional Materials, Autonomous Region, Institute of Applied Chemistry, Xinjiang University, Urumqi 830046, Xinjiang (China), Fax: (+86)?991‐8588883;2. National Anti‐counterfeit Engineering Research Center, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China) |
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| Abstract: | 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 1H 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 9.5×107 and 9.4×1010 s?1 for 1 b and 2 b , respectively. |
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| Keywords: | fluorescence kinetics photochromism pyrazolones semicarbazides |
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