We report O-H----S hydrogen-bond (H-bond) formation and its excited-state intramolecular H-bond on/off reaction unveiled by room-temperature phosphorescence (RTP). In this seminal work, this phenomenon is demonstrated with 7-hydroxy-2,2-dimethyl-2,3-dihydro-1 H-indene-1-thione (DM-7HIT), which possesses a strong polar (hydroxy)-dispersive (thione) type H-bond. Upon excitation, DM-7HIT exhibits anomalous dual RTP with maxima at 550 and 685 nm. This study found that the lowest lying excited state (S1) of DM-7HIT is a sulfur nonbonding (n) to π* transition, which undergoes O-H bond flipping from S1(nπ*) to the non-H-bonded S'1(nπ*) state, followed by intersystem crossing and internal conversion to populate the T'1(nπ*) state. Fast H-bond on/off switching then takes place between T'1(nπ*) and T1(nπ*), forming a pre-equilibrium that affords both the T'1(nπ*, 685 nm) and T1(nπ*, 550 nm) RTP. The generality of the sulfur H-bond on/off switching mechanism, dubbed a molecule wiper, was rigorously evaluated with a variety of other H-bonded thiones, and these results open a new chapter in the chemistry of hydrogen bonds.

中文翻译：

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基于硫的分子内氢键：具有双室温磷光的激发态氢键开/关开关

我们报告了由室温磷光 (RTP) 揭示的 OH----S 氢键 (H 键) 形成及其激发态分子内 H 键开/关反应。在这项开创性的工作中，这种现象用 7-羟基-2,2-二甲基-2,3-二氢-1 H-茚-1-硫酮 (DM-7HIT) 证明，它具有强极性（羟基）分散性（硫酮）型氢键。在激发后，DM-7HIT 表现出异常的双 RTP，最大值在 550 和 685 nm。该研究发现 DM-7HIT 的最低激发态 (S1) 是硫非键合 (n) 到 π* 跃迁，其经历了从 S1(nπ*) 到非 H 键合 S'1( nπ*) 状态，然后是系统间交叉和内部转换以填充 T'1(nπ*) 状态。然后在 T'1(nπ*) 和 T1(nπ*) 之间发生快速氢键开/关切换，形成提供 T'1(nπ*, 685 nm) 和 T1(nπ*, 550 nm) RTP 的预平衡。硫氢键开/关切换机制的通用性，被称为分子擦拭器，用各种其他氢键硫酮进行了严格评估，这些结果开启了氢键化学的新篇章。