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Mechanistic insight into the fluorescence activity of forensic fingerprinting reagents
journal contribution
posted on 2021-04-08, 13:39 authored by Lily Hunnisett, Paul F. Kelly, S Bleay, Felix PlasserFelix Plasser, R King, B McMurchie, Pooja GoddardPooja GoddardFingerprint detection is still the primary investigative technique for deciphering criminal inquiries and identifying individuals. The main
forensic fingerprinting reagents (FFRs) currently in use can require multiple treatment steps to produce fingerprints of sufficient quality.
Therefore, the development of new, more effective FFRs that require minimal chemical treatment is of great interest in forensic chemistry.
In this work, prudently crafted density functional theory and time-dependent density functional theory calculations are utilized to derive
mechanistic insight into the optical activity of the non-fluorescent product of ninhydrin, diketohydrindylidenediketohydrindamine (DYDA),
and fluorescent product of DFO (1,8-diazafluoren-9-one). We investigate various protonation sites to gain an understanding of isomeric
preference in the solid-state material. A relaxed scan of a single torsion angle rotation in the S1 minimized geometry of the O-protonated
DYDA isomer suggests a conical intersection upon ∼10○
rotation. We show that the absence of a rigid hydrogen-bonded network in the crystal
structure of DYDA supports the hypothesis of torsion rotation, which leads de-excitation to occur readily. Conversely, for the fluorescent
DFO product, our calculations support an avoided crossing suggestive of a non-radiative mechanism when the torsion angle is rotated by
about ∼100○
. This mechanistic insight concurs with experimental observations of fluorescence activity in DFO and may aid the photophysical
understanding of poorly visualized fingerprints due to weak fluorescence. We show that identifying suggestive avoided crossings via the
method described here can be used to initialize thoughts toward the computational design of FFRs.
History
School
- Science
Department
- Chemistry
Published in
The Journal of Chemical PhysicsVolume
154Issue
12Publisher
AIP PublishingVersion
- VoR (Version of Record)
Rights holder
© The AuthorsPublisher statement
This is an Open Access Article. It is published by AIP Publishing under the Creative Commons Attribution 4.0 International Licence (CC BY 4.0). Full details of this licence are available at: https://creativecommons.org/licenses/by/4.0/Acceptance date
2021-03-07Publication date
2021-03-31Copyright date
2021ISSN
0021-9606eISSN
1089-7690Publisher version
Language
- en