Control of photophysical properties and photoreactions of aromatic imides by use of intermolecular hydrogen bonding.
The effect of addition of alcohols on the photophysical properties and the photoreactions of N-methylphthalimide (1), N-methyl-1,8-, -2,3-, and -1,2-naphthalimide (2-4), and N-methyl-9,10-phenanthrenedicarboximide (5) has been investigated. The UV and IR spectra of aromatic imides 1-5 showed the presence of the intermolecular hydrogen bonding between the carbonyl group of the aromatic imides and the alcohols in less polar solvents. The equilibrium constants K for the hydrogen bonding were determined by the UV spectra. The fluorescence intensities of 2 and 1 were found to be remarkably and moderately enhanced by the addition of alcohols, respectively, though those of 3-5 were little enhanced by the addition of alcohols. On the other hand, photochemical cyclobutane formation of 2 with styrene (6) was found to be enhanced by the addition of 2,2,2-trifluoroethanol in benzene. Enhancement of the fluorescence quantum yields Phi(f) and the photoreaction of 2 by the hydrogen bond formation was explained by the decrease of the efficiency of the intersystem crossing from (1)(pi pi*) to (3)(n pi*), whose energy was increased by the hydrogen bonding.
Department of Materials Science, Faculty of Science and Engineering, Shimane University, Matsue, Shimane 690-8504, Japan. s049706@matsu.shimane-u.ac.jp
Kazuhiko
K
Matsubayashi
Yasuo
Y
Kubo
D006841:Hydrocarbons, Aromatic / Q000737:chemistry*; D006860:Hydrogen Bonding; D007094:Imides / Q000737:chemistry*; D008027:Light; D015394:Molecular Structure; D013050:Spectrometry, Fluorescence
D006841:Hydrocarbons, Aromatic; D007094:Imides