Mechanistic insight into the fluorescence activity of forensic fingerprinting reagents.
Hunnisett, L., Kelly, P F, Bleay, S., Plasser, F., King, R, McMurchie, B. and Goddard, P. (2021). Mechanistic insight into the fluorescence activity of forensic fingerprinting reagents. The Journal of Chemical Physics. 154 (12), p. 124313. https://doi.org/10.1063/5.0040555
|Hunnisett, L., Kelly, P F, Bleay, S., Plasser, F., King, R, McMurchie, B. and Goddard, P.
|Fingerprint 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 S 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.
|The Journal of Chemical Physics
|154 (12), p. 124313
|Digital Object Identifier (DOI)
|31 Mar 2021
|Publication process dates
|01 Mar 2021
|30 Apr 2021
|Accepted author manuscript
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This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Journal of Chemical Physics and may be found at https://aip.scitation.org/doi/10.1063/5.0040555
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