Substituent-controlled visible light photoisomerization and cyclodimerization of styryl pyrimidinones.
- 1Department of Chemical and Biomolecular Engineering, National University of Singapore E5, Engineering Drive 4 Singapore 117585 Singapore.
- 2Scientific Technological Center of Organic and Pharmaceutical Chemistry 26 Azatutyan Street Yerevan 0014 Armenia [email protected].
Abstract
Visible light-driven E/Z photoisomerization is an attractive strategy for controlling reactivity and biological activity; however, targeted design of heterocyclic bioactive compounds requires a solid understanding of how substituent effects govern productive isomerization and competing photochemical pathways. Here, a series of 6-methyl-2-styryl-pyrimidine-4(3H)-one derivatives with previously reported antifungal and antimicrobial activity of E-isomers were studied by LED-NMR spectroscopy under visiblelight irradiation at 405-450 nm. Pronounced substituent-dependent differences were observed in the efficiency of E/Z photoisomerization, the stability of the corresponding Z-isomers, and the formation of [2 + 2] cycloaddition products. Derivatives bearing electron-donating groups showed particularly efficient photoresponse, with up to 95% conversion to the Z-isomer within 1-3 h at moderate irradiation power below 1 W. The resulting Z-isomers showed appreciable thermal stability, with half-lives ranging from several hours to several days. Quantum chemical calculations were used to rationalize the observed substituent effects and photoreaction outcomes. Among the computed descriptors, the oscillator strength f S₁ (E) was found to be the most informative. This descriptor represented the absorption-related contribution to photoconversion, and favorable transition intensities were calculated for derivatives bearing OMe-type donor-substituted phenyl groups attached to the vinylene fragment. These results establish substituted 6-methyl-2-styryl-pyrimidine-4(3H)-ones as a visible light-responsive scaffold in which photoconversion, Z-isomer stability, and competing cycloaddition can be tuned by substituent design.
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BibTeX
@article{polynski2026substituentcontrolled,
title = {{Substituent-controlled visible light photoisomerization and cyclodimerization of styryl pyrimidinones.}},
author = {Mikhail V Polynski and Zaruhi A Hovasyan and Arthur A Harutyunyan and Astghik A Shahkhatuni and Aleksan G Shahkhatuni},
journal = {RSC advances},
year = {2026},
month = oct,
doi = {10.1039/d6ra06890a},
url = {https://europepmc.org/article/MED/42852146},
note = {CC BY},
}
RIS
TY - JOUR
TI - Substituent-controlled visible light photoisomerization and cyclodimerization of styryl pyrimidinones.
AU - Mikhail V Polynski
AU - Zaruhi A Hovasyan
AU - Arthur A Harutyunyan
AU - Astghik A Shahkhatuni
AU - Aleksan G Shahkhatuni
PY - 2026
DA - 2026/10/08
JO - RSC advances
DO - 10.1039/d6ra06890a
UR - https://europepmc.org/article/MED/42852146
AB - Visible light-driven E/Z photoisomerization is an attractive strategy for controlling reactivity and biological activity; however, targeted design of heterocyclic bioactive compounds requires a solid understanding of how substituent effects govern productive isomerization and competing photochemical pathways. Here, a series of 6-methyl-2-styryl-pyrimidine-4(3H)-one derivatives with previously reported antifungal and antimicrobial activity of E-isomers were studied by LED-NMR spectroscopy under visiblelight irradiation at 405-450 nm. Pronounced substituent-dependent differences were observed in the efficiency of E/Z photoisomerization, the stability of the corresponding Z-isomers, and the formation of [2 + 2] cycloaddition products. Derivatives bearing electron-donating groups showed particularly efficient photoresponse, with up to 95% conversion to the Z-isomer within 1-3 h at moderate irradiation power below 1 W. The resulting Z-isomers showed appreciable thermal stability, with half-lives ranging from several hours to several days. Quantum chemical calculations were used to rationalize the observed substituent effects and photoreaction outcomes. Among the computed descriptors, the oscillator strength f S₁ (E) was found to be the most informative. This descriptor represented the absorption-related contribution to photoconversion, and favorable transition intensities were calculated for derivatives bearing OMe-type donor-substituted phenyl groups attached to the vinylene fragment. These results establish substituted 6-methyl-2-styryl-pyrimidine-4(3H)-ones as a visible light-responsive scaffold in which photoconversion, Z-isomer stability, and competing cycloaddition can be tuned by substituent design.
SN - 2046-2069
ER -