RESONANT ION-DIP INFRARED SPECTROSCOPY OF 2-HYDROXYPYRIDINE AND ITS SMALL WATER CLUSTERS

Loading...
Thumbnail Image

Date

1999

Journal Title

Journal ISSN

Volume Title

Publisher

Ohio State University

Research Projects

Organizational Units

Journal Issue

Abstract

The structures and dynamics of 2-hydroxypyridine-$(water)_{n}$ clusters (with n=1 and 2) have been investigated using resonant two-photon ionization time-of-flight mass spectroscopy (R2PI-TOFMS), IR-UV hole-burning, and resonant ion-dip infrared spectroscopy (RIDIRS). The double resonance technique of RIDIRS provides both wavelength and mass selectivity in recording the hydride stretch infrared spectrum (2200 to $3800 cm^{-1}$) of a chosen cluster. The RIDIR spectrum of 2HOP monomer contains a narrow transition at $3598 cm ^1$, about $55 cm^{-}1$ lower in wavenumber than those of the corresponding hydroxy groups in phenol and cis/trans 2-naphthol. This suggests the presence of a weak intramolecular H-bond. The spectra of $2HOP-(H_{2}O)_{1} - 2$ contain sharp free OH stretch transitions near $3715 cm^{-}1$ and H-bonded OH stretch transitions in the $3100-3500 cm^{-}1$ region, which are remarkably broad (approaching $100 cm^{-}1$ in $2HOP-(H_{2}O)_{2})$ and show distinct sub-structure indicative of strong coupling to background states. A comparison with the results of density functional theory calculations indicates that the water molecules in $2HOP-(H_{2}O)_{1}$ and $2HOP-(H_{2}O)_{2}$ form bridges between the OH and N groups of 2HOP, accepting a H-bond from the OH group and donating a H-bond to the nitrogen lone pair. Possible reasons for the unusual breadth of these transitions will be put forward.

Description

Author Institution: Department of Chemistry, Purdue University

Keywords

Citation