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Stability and photoexcitation of oxygenated polycyclic aromatic hydrocarbons: The influence of water hydrogen-bonds

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Author(s):
Santos, Jose L. F. ; de Souza, Gabriel L. C.
Total Authors: 2
Document type: Journal article
Source: COMPUTATIONAL AND THEORETICAL CHEMISTRY; v. 1256, p. 8-pg., 2026-02-01.
Abstract

We performed a computational study of the ground state and five lowest excited singlet states of oxygenated polycyclic aromatic hydrocarbons (O-PAHs) derived from phenanthroline: 9,10-phenanthrenequinone, 4,7-phenanthroline-5,6-dione, and 1,10-phenanthroline-5,6-dione. Ground-and excited-state properties were determined using density functional theory (DFT) and time-dependent DFT, respectively, at the CAM-B3LYP/cc-pVTZ level of theory, in both gas phase and aqueous solution. Solvation was modeled through the polarizable continuum model (PCM) and a composite solvation model (CSM) combining explicit water molecules with PCM. Microsolvation stabilized preferential interactions at nitrogen sites and caused the emergence of a bright state in 9,10-phenanthrenequinone, absent in the gas phase. In contrast, 4,7-phenanthroline-5,6-dione and 1,10-phenanthroline-5,6-dione showed no bright states. These findings suggest that the combined presence of a diketone group and nitrogen heteroatoms may exert a significant influence on the photoabsorption process, thereby hindering the photodecomposition of O-PAHs in both the gas phase and aqueous solution, relative to the corresponding polycyclic aromatic hydrocarbons (PAHs) and nitrogen-containing PAHs (N-PAHs). (AU)

FAPESP's process: 23/11043-4 - Ionization of molecular aggregates of biological relevance
Grantee:Gabriel Luiz Cruz de Souza
Support Opportunities: Regular Research Grants