We performed DFT/TDDFT investigation on the sensing mechanism of the D–π–A type fluorescence probes 4-(5-R-thiophen-2-yl)-2-isobutyl-2H-[1,2,3]triazolo[4,5-e][1,2,4] triazolo[1,5-a]pyrimidines (ITTP₁, ITTP₂, ITTP₃), which are designed for detecting 2,4,6-trinitrophenol (TNP) explosive. Theoretical calculations reveal that the fluorescence sensing mechanism was induced by the combination of the π–π stacking interaction and photo-induced electron transfer. The blueshift in the UV–Vis spectrum of the ITTP sensors was correlated with the decrease in electron-donating ability of the molecule probes and was further evidenced by the calculated ¹H NMR spectra and D_CT index. The roles of the weak interactions: π–π stacking and hydrogen-bonding interaction for the probes fluorescence sensing process were analyzed, and the π–π stacking interaction was verified to be the dominant for the fluorescence sensing. The present finding should be useful for the future design of explosive fluorescent probes and the interpretation of the sensing mechanisms.

中文翻译：

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D–π–A型分子探针DFT / TDDFT研究4-（5-R-噻吩-2-基）-2-异丁基-2H- [1,2,3]三唑[4,5-e] [ 1,2,4]三唑并[1,5-a]嘧啶：荧光传感机制和弱相互作用的作用

我们对D–π–A型荧光探针4-（5-R-噻吩-2-基）-2-异丁基-2H- [1,2,3]三唑[4]的传感机理进行了DFT / TDDFT研究。 ，5-e] [1,2,4]三唑并[1,5-a]嘧啶（ITTP ₁，ITTP ₂，ITTP ₃），用于检测2,4,6-三硝基苯酚（TNP）炸药。理论计算表明，荧光感应机制是由π-π堆积相互作用和光诱导电子转移的结合所诱导的。ITTP传感器的UV-Vis光谱中的蓝移与分子探针的供电子能力下降相关，并由计算出的¹ H NMR光谱和D _CT进一步证明指数。分析了弱相互作用的作用：探针荧光传感过程中的π-π堆积和氢键相互作用，并证明了π-π堆积相互作用是荧光传感的主导。目前的发现对于爆炸性荧光探针的未来设计和传感机制的解释应该是有用的。