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Photoinduced proton transfer in 3-hydroxy-2-naphthoic acid

Mishra, Hirdyesh and Joshi, Hem Chandra and Tripathi, Hira Ballabh and Maheshwary, Shruti and Sathyamurthy, Narayanasami and Panda, Manoranjan and Chandrasekhar, Jayaraman (2001) Photoinduced proton transfer in 3-hydroxy-2-naphthoic acid. In: Journal Of Photochemistry And Photobiology A-Chemistry, 139 (1). pp. 23-36.

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Spectral and photophysical properties of 3-hydroxy-2-naphthoic acid (3HNA) have been investigated experimentally and theoretically. In addition to its normal fluorescence, 3HNA exhibits a large Stokes-shifted emission that depends on its concentration, the nature of the solvent, pH, temperature and excitation wavelength. 3HNA seems to form different emitting species in different media. The large Stokes shift is attributed to species undergoing excited state intramolecular proton transfer (ESIPT). Ab initio calculations using configuration interaction (single excitation) reveal a single minimum in the potential energy profile corresponding to the primary form in the ground state. While semi-empirical calculations with CI (AM1/PECI = 8) predict a double well potential, single point density functional theoretic calculations (B3LYP/6-31G**) confirm the absence of a barrier in the ground state for proton transfer. Ln the first excited singlet state, however, there are two minima corresponding to the primary and tautomeric forms at both ab initio CIS and AM1/PECI = 8 levels, thus accounting for the dual emission in 3HNA. The theoretical methods also account for the observed pH dependence of the spectral characteristics qualitatively correctly.

Item Type: Journal Article
Publication: Journal Of Photochemistry And Photobiology A-Chemistry
Publisher: Elsevier Science
Additional Information: Copyright of this article belongs to Elsevier Science.
Keywords: 3-hydroxy-2-naphthoic acid;excited state intramolecular proton transfer;hydrogen bonding
Department/Centre: Division of Chemical Sciences > Organic Chemistry
Date Deposited: 04 Feb 2010 08:59
Last Modified: 19 Sep 2010 04:56
URI: http://eprints.iisc.ac.in/id/eprint/17237

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