Shining light on the electronic structure and relaxation dynamics of the isolated oxyluciferin anion. Issue 34 (18th August 2020)

• Record Type: Journal Article
• Authors: Patel, Anand M.; Henley, Alice; Parkes, Michael A.; Assmann, Mariana; Worth, Graham A.; Anderson, James C.; Fielding, Helen H.
• Is Part Of: Physical chemistry chemical physics. Volume 22:Issue 34(2020)
• Page Start: 19022
• Page End: 19032
• Publication Date: 2020-08-18
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/d0cp03276j
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : A combined photoelectron spectroscopy and quantum chemistry study of the light emitting oxyluciferin anion. Copyright: photo of firefly, iStock/ruiruito. Abstract : Firefly bioluminescence is exploited widely in imaging in the biochemical and biomedical sciences; however, our fundamental understanding of the electronic structure and relaxation processes of the oxyluciferin that emits the light is still rudimentary. Here, we employ photoelectron spectroscopy and quantum chemistry calculations to investigate the electronic structure and relaxation of a series of model oxyluciferin anions. We find that changing the deprotonation site has a dramatic influence on the relaxation pathway following photoexcitation of higher lying electronically excited states. The keto form of the oxyluciferin anion is found to undergo internal conversion to the fluorescent S1 state, whereas we find evidence to suggest that the enol and enolate forms undergo internal conversion to a dipole bound state, possibly via the fluorescent S1 state. Partially resolved vibrational structure points towards the involvement of out-of-plane torsional motions in internal conversion to the dipole bound state, emphasising the combined electronic and structural role that the microenvironment plays in controlling the electronic relaxation pathway in the enzyme.