Abstract Twisted intramolecular charge transfer (TICT) and excited state intramolecular proton transfer (ESIPT) are of fundamental importance during the excited state dynamics of dyes and fluorescent sensors. Co-existence of the two processes usually complicates the whole photophysical process of dyes and leave the fluorescence detection mechanism of sensors uncovered. In this contribution, competition between the two processes are observed during the excited state relaxation of a fluorescence sensor 1-[(2-Amino-phenylimino)-methyl]-naphthalen-2-ol (short for L). Al3+ is proved to be capable of regulating this competition during the excited state deactivation process. With the addition of Al3+, the original barrier for the ESIPT process is removed and ESIPT fluorescence peak of the sensor is significantly enhanced. TICT process, which is originally barrier-less, is prohibited by the strong coordination between Al3+ and the sensor. The regulation of TICT and ESIPT process to achieve Al3+ detection is interesting and intrinsically different from the previously proposed sensing mechanism. The newly proposed mechanism is quite rare in the field of metal ion detection and may inspire scientists to design sensors from a different perspective.

中文翻译：

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Al3+ 调节化学传感器的 TICT 和 ESIPT 之间的竞争

摘要 扭曲分子内电荷转移 (TICT) 和激发态分子内质子转移 (ESIPT) 在染料和荧光传感器的激发态动力学过程中至关重要。这两个过程的共存通常会使染料的整个光物理过程复杂化，并使传感器的荧光检测机制未被发现。在这一贡献中，在荧光传感器 1-[(2-Amino-phenylimino)-methyl]-naphthalen-2-ol（L 的缩写）的激发态弛豫期间观察到这两个过程之间的竞争。Al3+ 被证明能够在激发态失活过程中调节这种竞争。随着Al3+的加入，ESIPT过程的原始障碍被消除，传感器的ESIPT荧光峰显着增强。TICT过程，原本是无障碍的，被Al3+与传感器的强配合所禁止。实现 Al3+ 检测的 TICT 和 ESIPT 过程的调节很有趣，并且与之前提出的传感机制有着本质的不同。新提出的机制在金属离子检测领域相当罕见，可能会启发科学家从不同的角度设计传感器。