Insight into the charge transfer mechanisms of heavy atom substituted MALDI matrices

Bridgmohan, Chelsea N.

Permalink

https://hdl.handle.net/2142/96966 Copy

Description

Title

Insight into the charge transfer mechanisms of heavy atom substituted MALDI matrices

Author(s)

Bridgmohan, Chelsea N.

Contributor(s)

• Kirmess, Kristopher M.
• Wang, Lichang

Issue Date

2017-06-21

Keyword(s)

Theory and computation

Abstract

"The underlying mechanism of how MALDI matrices work is poorly understood. Experimental literature suggests that the triplet excited state (T$_{1}$) of the matrix plays a significant role in its ability to transfer charge to the analyte effectively. The heavy atom substitution effect predicts that the addition of a heavy atom to an otherwise ""dead"" matrix, such as 2,4-dihydroxybenzoic acid, would increase the rate of Intersystem Crossing (ISC) to the T$_{1}$ state via spin-orbit coupling. This effect was observed experimentally as there was a visible decay in singlet lifetime and an increase in triplet lifetime, as well as a better matrix performance when compared to its original, unsubstituted partner. To provide insight into the photophysical properties of 2,4-dihydroxybenzoic acid and its halogenated isomers, calculations were performed using \textit{Gaussian09}. Geometry optimizations, frequencies, and IR spectra of all isomers were calculated using Density Functional Theory (DFT) with B3LYP functional and the 6-31G+(d,p) basis set. UV-Vis and fluorescence spectra were generated using Time-Dependent DFT (TDDFT). The following values for the singlet ground state (S$_{0}$), triplet excited state (T$_{1}$), and singlet excited state (S$_{1}$) were tabulated and compared: optimization energies, HOMO-LUMO energies and orbital contours, and bond distances. In addition, the energy values for Proton Affinity (PA) and Gas Phase Acidity (GPA) were determined."

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/96966

DOI

https://doi.org/10.15278/isms.2017.WI05

Copyright and License Information

Copyright 2017 Chelsea N. Bridgmohan

Owning Collections