Photo-induced ring-opening reaction of flav-3-en-2-ol monitored by time-resolved infrared spectroscopy
Photo-induced ring-opening reaction of flav-3-en-2-ol monitored by time-resolved infrared spectroscopy
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时间分辨红外光谱监测 flav-3-en-2-ol 的光诱导开环反应
DOI：
10.1021/acs.jpcb.9b07108
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Taka-aki Ishibashi
中科院分区：
文献类型：
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作者：
Masato Kondoh;Akira Sakuta;Kazuki Okazawa;Dai Akase;Misako Aida;Taka-aki Ishibashi
用时间分辨红外光谱和量子化学计算研究了由黄-3-烯-2-醇光诱导开环生成2-羟基查尔酮的反应。在黄-3-烯-2-醇光激发后的TR-IR光谱中，在1632 cm-1处观察到中间物质（电子基态的2-羟基查尔酮的烯醇形式）的C O伸缩模式振动带。我们还发现，2-羟基查尔酮酮在1664 cm-1处的C → O伸缩模在光激发后立即出现，并随着1632 cm-1谱带的耗尽而增强.由于1632 cm-1带的衰减和1664 cm-1带的上升符合双指数模型函数，其共同速率常数分别为0.5和11 μs-1，因此我们认为单键顺式-（s-cis-）和反式-（s-trans-）烯醇分别转化为酮式顺式-2-羟基查耳酮（Cc）和反式-2-羟基查耳酮（Ct）.量子化学计算的相关物种的红外光谱与建议是一致的。红外光谱的时间行为表明，在红外光谱仪的时间分辨范围内（~ 0.1 μs），除了通过2-羟基查尔酮的烯醇形式的反应途径外，还存在Cc和Ct的光生反应途径。
Photo-induced ring-opening reaction from flav-3-en-2-ol to 2-hydroxychalcone has been studied by time-resolved infrared (TR-IR) spectroscopy and quantum chemical calculations. A vibrational band due to the C═O stretching modes for intermediate species, enol forms of 2-hydroxychalcone in the electronic ground state, was observed at 1632 cm–1in the TR-IR spectra after photoexcitation of flav-3-en-2-ol. We also found that the C═O stretching modes of the keto forms of 2-hydroxychalcone at 1664 cm–1appeared immediately after photoexcitation and increased in intensity in synchronization with the depletion of the 1632 cm–1band. Because the decay of the 1632 cm–1band and the rise of the 1664 cm–1band were fitted with bi-exponential model functions with common rate constants 0.5 and 11 μs–1, we propose that two kinds of enol form, single bondcis- (s-cis-) andtrans- (s-trans-) enols, transformed into keto forms,cis-2-hydroxychalcone (Cc) andtrans-2-hydroxychalcone (Ct), respectively. Quantum chemically calculated IR spectra of related species are consistent with the proposal. The observed temporal behavior of the TR-IR spectra indicates that there were reaction paths to the photogeneration of Cc and Ct within the time resolution of the TR-IR spectrometer (∼0.1 μs) in addition to the reaction paths via the enol forms of 2-hydroxychalcone.