Solvent induced shifts of electronic spectra IV. Computational study on PRODAN fluorescence and implications to the excited state structure.
Vertical S(1)-S(0) electronic transitions of the highly solvent-sensitive fluorescence label 2-propionyl-6-dimethylamino naphthalene (PRODAN) are modeled by semiempirical CISD AM1 and TD DFT calculations in a large number of solvents of different polarity and hydrogen donating ability. Calculations correctly reproduce the observed solvent induced shifts of the emission maxima. The fluorescence Frank-Condon transition energies in solvent can be predicted quantitatively at the AM1 SM5.42 OPEN(2,2) C.I.=5 CISD level. For the planar PRODAN emitting state at the latter level we obtain a regression with practically unit slope and zero intercept for aprotic solvents. The respective relationship for the O-twisted S(1) state has a slope of 0.59 and intercept of 9100 cm(-1). These results support the concept that no geometry twist in the S(1) state of PRODAN is necessary to explain the observed solvent effects on fluorescence.
Bakalova
Snezhana M
SM
Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 9, 1113 Sofia, Bulgaria. bakalova@orgchm.bas.bg
Kaneti
Jose
J
D015081:2-Naphthylamine / Q000031:analogs & derivatives* / Q000737:chemistry; D000097:Acetonitriles / Q000737:chemistry; D003510:Cyclohexanes / Q000737:chemistry; D005453:Fluorescence; D008958:Models, Molecular; D012044:Regression Analysis; D012997:Solvents / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
D000097:Acetonitriles; D003510:Cyclohexanes; D012997:Solvents; C506365:Cyclohexane; C038517:prodan; D015081:2-Naphthylamine; C032159:acetonitrile