Spectral, luminescent, and photophysical properties of dipyrrolylbenzenes

• Published in: Russian chemical bulletin Vol. 57; no. 7; pp. 1461 - 1466
• Main Authors: Petrushenko, I. K., Petrushenko, K. B., Smirnov, V. I., Trofimov, B. A.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.07.2008
• Subjects: Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Full Articles; Inorganic Chemistry; Organic Chemistry; molecular conformations; photophysical properties; 1,4-bis(pyrrol-2-yl)benzene; 1,4-bis(1-vinylpyrrol-2-yl)benzene; fluorescence; 4-(1-vinylpyrrol-2-yl)-1-(pyrrol-2-yl)benzene; quantum chemical calculations; TD density functional theory
• ISSN: 1066-5285; 1573-9171
• DOI: 10.1007/s11172-008-0189-2

Dipyrroles with a phenylene bridge, 1,4-bis(pyrrol-2-yl)benzene, 4-(1-vinylpyrrol-2-yl)-1-(pyrrol-2-yl)benzene, and 1,4-bis(1-vinylpyrrol-2-yl)benzene, show intense room-temperature fluorescence in solutions. Analysis of electronic absorption spectra, fluorescence spectra, and results of B3LYP, TD B3LYP, and CIS quantum chemical calculations showed that the introduction of a bulky substituent in position 1 of the pyrrole ring makes the ground-state structures of dipyrrolylbenzenes less planar. Excited-state geometries of all molecules relax to more planar conformations. An increase in the probability of nonradiative transitions has little effect on the quantum yields of fluorescence (Φ f ) of dipyrrolylbenzenes. Even for 1,4-bis(1-vinylpyrrol-2-yl)benzene, where the pyrrole rings deviate from the benzene ring plane by 44°, the fluorescence efficiency remains high enough (Φ f = 0.7). Substitution at nitrogen atoms has little effect on positions of fluorescence band maxima.