The excited state hydrogen bonding interactions and intramolecular proton transfer (ESIPT) process for 2‐(quinolin‐2‐yl)‐3‐hydroxy‐4H‐chromen‐4‐one (Qu3HC) system has been theoretically studied via density functional theory (DFT) and time‐dependent DFT (TDDFT) methods. We confirmed that the reversible tuning of intramolecular hydrogen bonding direction is impossible for Qu3HC system. Then, we have studied the S₀‐state and S₁‐state hydrogen bonding dynamical behaviors of Qu3HC structure and confirmed that the strengthening of intramolecular hydrogen bond in the S₁ state could facilitate ESIPT reaction. Given photo‐induced excitation, we find that the charge redistribution around hydroxyl moiety plays important roles in providing driving force for ESIPT. Our constructed potential energy curves further verify that the ESIPT process of Qu3HC should be ultrafast due to low potential barrier. With the addition of fluoride anions, the exothermal deprotonation process occurs spontaneously along with the intermolecular hydrogen bond O–H···F, which reveals the uniqueness of detecting fluoride anion using Qu3HC molecule. As a whole, the fluoride anion inhibits the initial ESIPT process of Qu3HC, which results in different fluorescence behaviors.

中文翻译：

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基于抑制激发态分子内超快质子转移的2-（喹啉-2-基）-3-羟基-4H-铬n-4-酮化学传感器的氟阴离子传感机理

激发态氢键相互作用和分子内质子转移（ESIPT）工艺为2-（喹啉-2-基）-3-羟基-4- ħ -苯并吡喃-4-酮（Qu3HC）系统已经在理论上通过密度泛函理论的研究（ DFT）和时间相关DFT（TDDFT）方法。我们证实对于Qu3HC系统，分子内氢键方向的可逆调节是不可能的。然后，我们研究了Qu3HC结构的S _0态和S _1态氢键动力学行为，并证实了S ₁分子内氢键的增强状态可以促进ESIPT反应。给定光诱导的激发，我们发现羟基部分周围的电荷重新分布在为ESIPT提供驱动力方面起着重要作用。我们构建的势能曲线进一步验证了Qu3HC的ESIPT过程由于势垒低而应该超快。加入氟离子后，放热去质子过程与分子间氢键O–H···F一起自发发生，这揭示了使用Qu3HC分子检测氟离子的独特性。总体而言，氟阴离子抑制Qu3HC的初始ESIPT过程，从而导致不同的荧光行为。