Sulfur-Based Intramolecular Hydrogen-Bond: Excited-State Hydrogen-Bond On/Off Switch with Dual Room-Temperature Phosphorescence

Zong Ying Liu, Jiun Wei Hu, Chun Hao Huang, Teng Hsing Huang, Deng Gao Chen, Ssu Yu Ho, Kew Yu Chen, Elise Y. Li, Pi Tai Chou

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Abstract

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-1H-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.

Original languageEnglish
Pages (from-to)9885-9894
Number of pages10
JournalJournal of the American Chemical Society
Volume141
Issue number25
DOIs
Publication statusPublished - 2019 Jun 26

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ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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