Torsion-induced fluorescence quenching in excited-state intramolecular proton transfer (ESIPT) dyes

Sehoon Kim, Jangwon Seo, Soo Young Park

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)


Fluorescence quenching behaviors of four known excited-state intramolecular proton transfer (ESIPT) molecules have been studied by semiempirical and ab initio calculations. The ESIPT compounds studied in this work are assorted into two sets depending on the N-containing ring structure (5- and 6-membered rings). It has been found that twisted intramolecular charge transfer (TICT) process in the excited keto state (K*) after ESIPT, one of the possible quenching pathways of ESIPT fluorescence, is significantly influenced by the geometrical properties of intramolecular hydrogen (H) bond associated with the N-containing ring structure. The compounds with 5-membered ring have efficient ESIPT emission with large barrier to fluorescence-quenching TICT state, due to appropriate stabilization of planar K* through intramolecular H bond. For the compounds with 6-membered ring, however, ESIPT emission is completely quenched due to significantly lowered barrier resulting from too short H-bond length. The effect of intramolecular H bond on the TICT reaction potential has been discussed in detail from the viewpoints of molecular structure and torsional motion, with the help of elaborate model compound studies.

Original languageEnglish
Pages (from-to)19-24
Number of pages6
JournalJournal of Photochemistry and Photobiology A: Chemistry
Issue number1
Publication statusPublished - 2007 Sept 7

Bibliographical note

Funding Information:
This work was supported by the Korea Science and Engineering Foundation (KOSEF) through the National Research Lab. Program funded by the Ministry of Science and Technology (No. 2006-032246).


  • Excited-state intramolecular proton transfer (ESIPT)
  • Fluorescence quenching
  • Intramolecular hydrogen bond
  • Semiempirical and ab initio calculations
  • Twisted intramolecular charge transfer (TICT)

ASJC Scopus subject areas

  • General Chemistry
  • General Chemical Engineering
  • General Physics and Astronomy


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