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Dual excited-state intramolecular proton transfer reaction in 3-hydroxy-2-(pyridin-2-yl)-4H-chromen-4-one.
J Phys Chem A. 2009 Jan 08; 113(1):205-14.JP

Abstract

The synthesis, characterization and fundamental of the dual excited-state proton-transfer properties of 3-hydroxy-2-(pyridin-2-yl)-4H-chromen-4-one (1a) are reported. In the electronic ground state, there exist two competitive hydrogen bonding (HB) isomers for 1a. Conformer 1a(O) reveals a five-membered ring HB structure between O-H and carbonyl oxygen, while conformer 1a(N) possesses a six-membered ring HB formation between O-H and pyridyl nitrogen. In a single crystal, the X-ray crystallography unveils an exclusive formation of conformer 1a(N). In solution such as CH(2)Cl(2), 1a(O) and 1a(N) are in equilibrium, and their respective absorption chromophores are significantly different due to different degrees of hydrogen-bond induced pi electron delocalization. Upon excitation, both conformers 1a(O) and 1a(N) undergo excited-state intramolecular proton transfer (ESIPT) reaction. Following ESIPT, 1a(O) gives rise to a tautomer emission maximized at 534 nm in CH(2)Cl(2). Conversely, due to dominant radiationless quenching processes the tautomer emission for 1a(N) cannot be obtained with a steady-state manner but can be resolved from time-resolved fluorescence. Time resolved fluorescence estimates an equilibrium constant of 27 +/- 5 in favor of 1a(N) in CH(2)Cl(2). Ultrafast ESIPT also takes place for the unique 1a(N) form in the crystal. Due to the prohibition of quenching processes in the solid state, bright tautomer emission maximized at 540 nm is resolved for 1a(N) (Phi(f) approximately 0.3). The interplay between two HB conformers with on(1a(O))/off(1a(N)) character in tautomer emission may find future applications such as the recognition of organic Lewis acid/base in organic solvents.

Authors+Show Affiliations

Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan, ROC.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

19072622

Citation

Chen, Chyi-Lin, et al. "Dual Excited-state Intramolecular Proton Transfer Reaction in 3-hydroxy-2-(pyridin-2-yl)-4H-chromen-4-one." The Journal of Physical Chemistry. A, vol. 113, no. 1, 2009, pp. 205-14.
Chen CL, Lin CW, Hsieh CC, et al. Dual excited-state intramolecular proton transfer reaction in 3-hydroxy-2-(pyridin-2-yl)-4H-chromen-4-one. J Phys Chem A. 2009;113(1):205-14.
Chen, C. L., Lin, C. W., Hsieh, C. C., Lai, C. H., Lee, G. H., Wang, C. C., & Chou, P. T. (2009). Dual excited-state intramolecular proton transfer reaction in 3-hydroxy-2-(pyridin-2-yl)-4H-chromen-4-one. The Journal of Physical Chemistry. A, 113(1), 205-14. https://doi.org/10.1021/jp809072a
Chen CL, et al. Dual Excited-state Intramolecular Proton Transfer Reaction in 3-hydroxy-2-(pyridin-2-yl)-4H-chromen-4-one. J Phys Chem A. 2009 Jan 8;113(1):205-14. PubMed PMID: 19072622.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Dual excited-state intramolecular proton transfer reaction in 3-hydroxy-2-(pyridin-2-yl)-4H-chromen-4-one. AU - Chen,Chyi-Lin, AU - Lin,Chun-Wei, AU - Hsieh,Cheng-Chih, AU - Lai,Chin-Hung, AU - Lee,Gene-Hsiang, AU - Wang,Chih-Chieh, AU - Chou,Pi-Tai, PY - 2008/12/17/entrez PY - 2008/12/17/pubmed PY - 2009/2/20/medline SP - 205 EP - 14 JF - The journal of physical chemistry. A JO - J Phys Chem A VL - 113 IS - 1 N2 - The synthesis, characterization and fundamental of the dual excited-state proton-transfer properties of 3-hydroxy-2-(pyridin-2-yl)-4H-chromen-4-one (1a) are reported. In the electronic ground state, there exist two competitive hydrogen bonding (HB) isomers for 1a. Conformer 1a(O) reveals a five-membered ring HB structure between O-H and carbonyl oxygen, while conformer 1a(N) possesses a six-membered ring HB formation between O-H and pyridyl nitrogen. In a single crystal, the X-ray crystallography unveils an exclusive formation of conformer 1a(N). In solution such as CH(2)Cl(2), 1a(O) and 1a(N) are in equilibrium, and their respective absorption chromophores are significantly different due to different degrees of hydrogen-bond induced pi electron delocalization. Upon excitation, both conformers 1a(O) and 1a(N) undergo excited-state intramolecular proton transfer (ESIPT) reaction. Following ESIPT, 1a(O) gives rise to a tautomer emission maximized at 534 nm in CH(2)Cl(2). Conversely, due to dominant radiationless quenching processes the tautomer emission for 1a(N) cannot be obtained with a steady-state manner but can be resolved from time-resolved fluorescence. Time resolved fluorescence estimates an equilibrium constant of 27 +/- 5 in favor of 1a(N) in CH(2)Cl(2). Ultrafast ESIPT also takes place for the unique 1a(N) form in the crystal. Due to the prohibition of quenching processes in the solid state, bright tautomer emission maximized at 540 nm is resolved for 1a(N) (Phi(f) approximately 0.3). The interplay between two HB conformers with on(1a(O))/off(1a(N)) character in tautomer emission may find future applications such as the recognition of organic Lewis acid/base in organic solvents. SN - 1520-5215 UR - https://www.unboundmedicine.com/medline/citation/19072622/Dual_excited_state_intramolecular_proton_transfer_reaction_in_3_hydroxy_2__pyridin_2_yl__4H_chromen_4_one_ L2 - https://doi.org/10.1021/jp809072a DB - PRIME DP - Unbound Medicine ER -