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Base Triggered Enhancement of First Hyperpolarizability of a Keto-Enol Tautomer

De, Soumi and Ray, Manisha and Pati, Anusooya Y and Das, Puspendu K (2013) Base Triggered Enhancement of First Hyperpolarizability of a Keto-Enol Tautomer. In: JOURNAL OF PHYSICAL CHEMISTRY B, 117 (48). pp. 15086-15092.

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Official URL: http://dx.doi.org/10.1021/jp410368z

Abstract

This work describes the base triggered enhancement of first hyperpolarizability of a tautomeric organic molecule, namely, benzoylacetanilide (BA). We have used the hyper-Rayleigh scattering technique to measure the first hyperpolarizability (beta) of BA which exists in the pure keto form in water and as a keto-enol tautomer in ethanol. Its anion exists in equilibrium with the keto and enol forms at pH 11 in aqueous solution. The beta value of the anion form is 709 X 10(-30) esu, whereas that of the enol is 232 x 10(-3) esu and of the keto is 88 X 10(-30) esu. There is an enhancement of beta by similar to 8 times for the anion and similar to 3 times for the enol compared to the keto form. All these are achieved by altering the equilibrium between the three forms of BA by simple means. MP2 calculations reproduce the experimental trend, but the computed beta values are much lower than the measured values. DFT calculations with the standard B3LYP functional could not predict the right order in the beta values. The difference between experimental and calculated values is, perhaps, due to the fact that electron correlation effects are important in computing optical nonlinearities of large organic molecules and MP2 and B3LYP calculations done here for different forms of BA could not account for such effects adequately.

Item Type: Journal Article
Additional Information: copyright for this article belongs to AMER CHEMICAL SOC,USA
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Depositing User: Id for Latest eprints
Date Deposited: 07 Jan 2014 05:39
Last Modified: 07 Jan 2014 05:39
URI: http://eprints.iisc.ac.in/id/eprint/48140

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