A density functional theory based analysis of photoinduced electron transfer in a triazacryptand based K+ sensor

Briggs, Edward A. and Besley, Nicholas A. (2015) A density functional theory based analysis of photoinduced electron transfer in a triazacryptand based K+ sensor. Journal of Physical Chemistry A, 119 (12). pp. 2902-2907. ISSN 1089-5639

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The electronic structure and photoinduced electron transfer processes in a K+ fluorescent sensor that comprises a 4-amino-naphthalimide derived fluorophore with a triazacryptand lig- and is investigated using density functional theory (DFT) and time-dependent density functional theory (TDDFT) in order to rationalise the function of the sensor. The absorption and emission energies of the intense electronic excitation localised on the fluorophore are accurately described using a ∆SCF Kohn-Sham DFT approach, which gives excitation energies closer to experiment than TDDFT. Analysis of the molecular orbital diagram arising from DFT calculations for the isolated molecule or with implicit solvent cannot account for the function of the sensor and it is necessary to consider the relative energies of the electronic states formed from the local excitation on the fluorophore and the lowest fluorophore→chelator charge transfer state. The inclusion of solvent in these calculations is critical since the strong interaction of the charge transfer state with the solvent lowers it energy below the local fluorophore excited state making a reductive photoinduced electron transfer possible in the absence of K+, while no such process is possible when the sensor is bound to K+. The rate of electron transfer is quantified using Marcus theory, which gives a rate of electron transfer of k_ET=5.98 x 10^6 s−1.

Item Type: Article
Additional Information: This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Physical Chemistry A, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/acs.jpca.5b01124.
Keywords: photoinduced electron transfer, density functional theory
Schools/Departments: University of Nottingham UK Campus > Faculty of Science > School of Chemistry
Identification Number: https://doi.org/10.1021/acs.jpca.5b01124
Depositing User: Besley, Nick
Date Deposited: 02 Mar 2016 14:19
Last Modified: 15 Sep 2016 21:00
URI: http://eprints.nottingham.ac.uk/id/eprint/32088

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