TY - JOUR
T1 - Torsion-induced fluorescence quenching in excited-state intramolecular proton transfer (ESIPT) dyes
AU - Kim, Sehoon
AU - Seo, Jangwon
AU - Park, Soo Young
N1 - 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).
PY - 2007/9/7
Y1 - 2007/9/7
N2 - 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.
AB - 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.
KW - Excited-state intramolecular proton transfer (ESIPT)
KW - Fluorescence quenching
KW - Intramolecular hydrogen bond
KW - Semiempirical and ab initio calculations
KW - Twisted intramolecular charge transfer (TICT)
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U2 - 10.1016/j.jphotochem.2007.03.026
DO - 10.1016/j.jphotochem.2007.03.026
M3 - Article
AN - SCOPUS:34547667161
VL - 191
SP - 19
EP - 24
JO - Journal of Photochemistry and Photobiology A: Chemistry
JF - Journal of Photochemistry and Photobiology A: Chemistry
SN - 1010-6030
IS - 1
ER -