Hydrogen Bound Complexes With Tropolone: Binding Motifs, Barrier Heights, And The Search For Bifurcating Systems

Nemchick, Deacon

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https://hdl.handle.net/2142/50989 Copy

Description

Title

Hydrogen Bound Complexes With Tropolone: Binding Motifs, Barrier Heights, And The Search For Bifurcating Systems

Author(s)

Nemchick, Deacon

Contributor(s)

• Vaccaro, Patrick
• Chew, Kathryn

Issue Date

2014-06-19

Keyword(s)

Clusters/Complexes

Abstract

The potentially frustrated transfer of a proton between the hydroxylic (proton-donating) and ketonic (proton-accepting) oxygen atom centers in tropolone (TrOH) long has served as a model system for the study of coherent (symmetrical) proton-transfer events. A litany of hydrogen-bound complexes [TrOH $\cdot$ X\textit{$_{n}$}] can be formed \textit{in situ} by docking amphoteric ligands onto the TrOH substrate under supersonic free-jet expansion conditions. Binary (\textit{n} = 1) and higher order (\textit{n} = 2, 3, \ldots) complexes formed with formic acid, hydrogen fluoride, acetic acid and propiolic acid (X = FA, HF, AA, and PA) have been synthesized and interrogated using a variety of spectroscopic probes built upon the intense \textit{\~{A}$^{1}$}B$_{2}$$-$\textit{\~{X}$^{1}$}{A}$_{1}$ ($\pi ^{*}\leftarrow\pi$) near-ultraviolet absorption system of bare tropolone, thereby providing vibronically resolved information through combined use of laser-induced fluorescence (LIF), dispersed fluorescence (DF), fluorescence hole-burning (FHB), and stimulated emission pumping (SEP) methods. Experimental results reveal the propensity for binary complexes to adopt a higher-energy external binding motif (ligand attached to the seven membered aromatic ring) over the energetically preferred internal form (ligand bound to the O$-$H$\cdots$O reaction center), where the latter cleft-bound species can undergo unique symmetric (coherent) double proton-transfer reactions. These findings will be discussed in light of supporting quantum-chemical calculations.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

English

Permalink

http://hdl.handle.net/2142/50989

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Copyright 2014 by the authors. Licensed under a Creative Commons Attribution 4.0 International License. http://creativecommons.org/licenses/by/4.0/

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