The carbonyl-lock mechanism underlying non-aromatic fluorescence in biological matter

Mirón, Gonzalo Díaz; Semelak, Jonathan A.; Grisanti, Luca; Rodriguez, Alex; Conti, Irene; Stella, Martina; Velusamy, Jayaramakrishnan; Seriani, Nicola; Došlić, Nađa; Rivalta, Ivan; Garavelli, Marco; Estrin, Dario A.; Kaminski Schierle, Gabriele S.; González Lebrero, Mariano C.; Hassanali, Ali; Morzan, Uriel N. (2023) The carbonyl-lock mechanism underlying non-aromatic fluorescence in biological matter. Nature Communications, 14 (1). ISSN 2041-1723

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Abstract

Challenging the basis of our chemical intuition, recent experimental evidence reveals the presence of a new type of intrinsic fluorescence in biomolecules that exists even in the absence of aromatic or electronically conjugated chemical compounds. The origin of this phenomenon has remained elusive so far. In the present study, we identify a mechanism underlying this new type of fluorescence in different biological aggregates. By employing non-adiabatic ab initio molecular dynamics simulations combined with a data-driven approach, we characterize the typical ultrafast non-radiative relaxation pathways active in non-fluorescent peptides. We show that the key vibrational mode for the non-radiative decay towards the ground state is the carbonyl elongation. Non-aromatic fluorescence appears to emerge from blocking this mode with strong local interactions such as hydrogen bonds. While we cannot rule out the existence of alternative non-aromatic fluorescence mechanisms in other systems, we demonstrate that this carbonyl-lock mechanism for trapping the excited state leads to the fluorescence yield increase observed experimentally, and set the stage for design principles to realize novel non-invasive biocompatible probes with applications in bioimaging, sensing, and biophotonics.

Item Type:	Article
Uncontrolled Keywords:	intrinsic fluorescence; non-aromatic fluorescence; carbonyl elongation; carbonyl-lock mechanism
Subjects:	NATURAL SCIENCES > Chemistry > Physical Chemistry
Divisions:	Theoretical Physics Division
Depositing User:	Ivana Vuglec
Date Deposited:	31 Mar 2026 11:53
URI:	http://fulir.irb.hr/id/eprint/11554
DOI:	10.1038/s41467-023-42874-3

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