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Informing the design of amino-acid fingerprinting reagents using density functional theory

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thesis
posted on 25.05.2021, 11:57 by Lily Hunnisett
Improving the effectiveness of forensic fingerprinting reagents (FFRs) has been a challenge in the field of forensic chemistry for the previous four decades. Fluorescent methods offer significant improvement over their non-fluorescent counter parts and the focus of several previous studies have been to develop new fluorescent FFRs via a synthetic trial-and-error process. In this study, a computational Density Functional Theory (DFT) approach is used to work towards predicting the fluorescence activity of a system in an attempt to contribute to the development process.

Aiming to inform the fluorescent FFR design process, this study asks: Is time-dependant DFT (TDDFT) able to replicate non-fluorescent behaviour of existing FFRs by identifying non-radiative features along their excited state potential energy surface (PES)? Reporting the validation of TDDFT as a predictive tool, this study presents the accurate calculation of optical properties belonging to products of the existing FFRs, 2,2-dihydroxyindane-1,3-dione (ninhydrin) and 1,8-diazafluoren-9-one (DFO), and has proposed chemical structures of the products of 1,2-indanedione and 2-hydroxy-1,4-napthoquinone (lawsone). Investigation of the PES representing a mechanism related to excited state intramolecular proton transfer (ESIPT) in the ninhydrin product, DYDA, and the DFO product revealed non-radiative characteristics in the former, indicating that an internal 10° dihedral rotation of DYDA leads to a non-radiative relaxation mechanism. The relevance of these findings with respect to the solid-state structures is also offered through analysis of the crystal packing in previously reported X-ray crystal structures.

It is recommended that further investigation be carried out on a larger set of chromophoric systems to further validate the presented workflow, validation of which will offer an informative predictive tool to be utilised in a product-to-reactant approach to the design of new fluorescent FFRs.

History

School

  • Science

Department

  • Chemistry

Publisher

Loughborough University

Rights holder

© L.M. Hunnisett

Publication date

2020

Notes

A thesis submitted in partial fulfilment of the requirements for the award of the degree of Doctor of Philosophy of Loughborough University.

Language

en

Supervisor(s)

Pooja Goddard ; Paul Kelly

Qualification name

PhD

Qualification level

Doctoral

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