Fluorescent detection mechanism of CO-releasing molecule-3: Competition of inter-/intra-molecular hydrogen bonds.
Fluorescent detection mechanism of CO-releasing molecule-3: Competition of inter-/intra-molecular hydrogen bonds.
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DOI：
10.1016/j.saa.2021.120227
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发表时间：
2021-07
期刊：
影响因子：
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通讯作者：
Yonggang Yang;Yang Liu;Kai Jiang;Yufang Liu
中科院分区：
文献类型：
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作者：
Yonggang Yang;Yang Liu;Kai Jiang;Yufang Liu
从理论上研究了2-（4-硝基-1，3-二氧代异吲哚啉-2-基）乙酸（CORM 3-绿色）对CO释放分子-3（CORM-3）的荧光检测机理。当与CORM-3反应时，非荧光的CORM-3-绿色被转移到2-（4-氨基-1，3-二氧代异吲哚啉-2-基）乙酸（PTI）的酮形式，产生位于423 nm处的强荧光峰。该峰红移至489 nm，这是由PTI和水分子之间的分子间氢键（HB）的增强引起的，并归因于实验观察到的503 nm处的荧光发射。这一结果与以往报道的实验荧光对应于质子转移烯醇形式的PTI的结果有很大不同。为了说明这种混淆，计算的PTI-Enol的荧光峰位于689 nm处，这比实验结果大得多。该结果排除了激发态分子内质子转移（ESIPT）的发生。结论是分子间的HB阻碍了分子内HB的形成和酮式PTI的ESIPT。这一结论证实了113 nm的实验斯托克斯位移主要是由分子间氢键而不是ESIPT过程引起的。本工作对CORM 3-绿色的检测机理和实验荧光现象提出了合理的解释。
The fluorescent detection mechanism of 2-(4-nitro-1,3-dioxoisoindolin-2-yl) acetic acid (CORM3-green) on CO-Releasing Molecule-3 (CORM-3) is theoretically studied. Upon reaction with CORM-3, the non-fluorescent CORM3-green is transferred to the keto form of 2-(4-amino-1,3-dioxoisoindolin-2-yl)acetic acid (PTI) to produce strong fluorescence peak located at 423 nm. This peak red-shifts to 489 nm, which is induced by the strengthening of intermolecular hydrogen bond (HB) between PTI and water molecules and attributed to the experimentally observed fluorescence emission at 503 nm. This result is dramatically different from previous reports that the experimental fluorescence corresponds to the proton transferred enol form of PTI. To illustrate this confusion, the calculated fluorescence peak of PTI-Enol is located at 689 nm, which is much larger than that of experimental result. This result excludes the occurrence of excited state intramolecular proton transfer (ESIPT). It is concluded that intermolecular HBs hinders the formation of intramolecular HB and the ESIPT of the keto form of PTI. This conclusion confirms that experimental Stokes shift of 113 nm is mainly caused by the intermolecular hydrogen bonding rather than by ESIPT process. This work proposes a reasonable explanation for the detection mechanism of CORM3-green and experimental fluorescence phenomenon.