Journal article
Polarization Effects for Hydrogen-Bonded Complexes of Substituted Phenols with Water and Chloride Ion
Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520-81071
Variations in hydrogen-bond strengths are investigated for complexes of nine para-substituted phenols (XPhOH) with a water molecule and chloride ion. Results from ab initio HF/6-311+G(d, p) and MP2/6-311+G(d, p)//HF/6-311+G(d, p) calculations are compared with those from the OPLS-AA and OPLS/CM1A force fields.
In the OPLS-AA model, the partial charges on the hydroxyl group of phenol are not affected by the choice of para substituent, while the use of CM1A charges in the OPLS/CM1A approach does provide charge redistribution. The ab initio calculations reveal a 2.0-kcal/mol range in hydrogen-bond strengths for the XPhOH⋯OH2 complexes in the order X = NO2 > CN > CF3 > Cl > F > H >OH >CH3 > NH2.
The pattern is not well-reproduced with OPLS-AA, which also compresses the variation to 0.7 kcal/mol. However, the OPLS/CM1A results are in good accord with the ab initio findings for both the ordering and range, 2.3 kcal/mol. The hydrogen bonding is, of course, weaker with XPhOH as acceptor, the order for X is largely inverted, and the range is reduced to ca. 1.0 kcal/mol.
The substituent effects are found to be much greater for the chloride ion complexes with a range of 11 kcal/mol. For quantitative treatment of such strong ion-molecule interactions the need for fully polarizable force fields is demonstrated.
Language: | English |
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Publisher: | American Chemical Society (ACS) |
Year: | 2010 |
Pages: | 1987-1992 |
ISSN: | 15499626 and 15499618 |
Types: | Journal article |
DOI: | 10.1021/ct7001754 |