HYDROPHOBIC EFFECTS ON PHOTOPHYSICAL AND PHOTOCHEMICAL PROCESSES - NEW FLUORESCENCE FROM MOLECULAR AGGREGATES OF 1,4-DI(2-NAPHTHYL)CYCLOHEXANE .11.

The UV absorption and fluorescence spectra of trans- and cis-1,4-di(2-naphthyl)cyclohexane (DNCH) in water-organic binary mixtures have been investigated. In organic solvents, they only emit monomer fluorescence of the naphthyl chromophore. However, in the mixed solvents, the fluorescence spectra were dominated by dimer emission, and the UV absorption spectra are significantly red-shifted. This suggests that in the binary mixtures the hydrophobic interaction forces DNCH molecules to aggregate, and inside the aggregate the naphthyl groups of different DNCH molecules overlap and interact with each other to form an intermolecular dimer. The effect of temperature on the fluorescence spectra was studied. © 1990.