Substituent effects of halogens on the excited-state intermolecular proton transfer reactions.
Photochem Photobiol Sci
; 23(7): 1341-1352, 2024 Jul.
Article
in En
| MEDLINE
| ID: mdl-38850493
ABSTRACT
Fluorescent aromatic urea compounds undergo excited-state intermolecular proton transfer (ESPT) in the presence of acetate anions to produce an excited state of the tautomer (T*) from the excited state of the complex (N*), resulting in dual fluorescence. Herein, we performed spectroscopic measurements of anthracen-1-yl-3-phenylurea derivatives with substituents, -CF3, -F, or -Cl, at the p-position of the phenyl group in the presence of acetate to investigate the substituent effects on the ESPT reaction and the deactivation processes of N* and T*. Kinetic analysis showed that the reverse ESPT rate constant (k-PT) depended on the respective substituents, suggesting that each substituent may influence the reverse ESPT process differently. In particular, since the electron-withdrawing properties of -F are estimated by the - I and + Iπ effects, it is plausible that -F has a slight electron-donating property and influences the reverse process from T* to N* in the excited state. This study shows that it is possible to control emission by selecting specific substituents in the ESPT system.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
Photochem Photobiol Sci
Journal subject:
BIOLOGIA
/
QUIMICA
Year:
2024
Document type:
Article
Affiliation country:
Japan
Country of publication:
United kingdom