MOLECULAR ORBITAL STUDIES OF HYDROGEN BONDS IN EXCITED STATES
Loading...
Date
1972
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
Molecular orbital theories of hydrogen bonds have made a remarkable progress in the last few years. Among others, the interaction between $H_{2}O$ molecules and between $H_{2}O$ and a carbonyl group has been extensively studied. In this report we apply the same technique to the hydrogen bonding of an excited molecule. The importance of hydorgen bonds in the excited state has been recognized in numerous spectroscopic observations. Especially the nature of the hydrogen bond interaction to the excited carbonyl group is of particular interest in biochemistry and solution photochemistry. We carry out ab initio LCAO MO SCF and SCF CI calculations for the complex between the $n \rightarrow \Pi^{*}$ excited $H_{2}CO$ (both singlet and triplet) and the ground state $H_{2}O$. The Frank-Condon and equilibrium geometries of the excited $H_{2}CO$ are used. The modes of interaction - the distance between HO and CO groups, the direction of approach of the HO group and the relative direction of the non-interacting OH bond with respect to the C=0 group - are carefully examined. The $\Pi$ hydrogen-bond, in which the HO group approaches to the $\Pi$ orbital of the CO group and which is considered important for the excited $H_{2}CO$, is also extensively studied.
Description
Author Institution: Department of Chemistry, University of Rochester