The fluorescence spectra of bis(4-methoxyphenyl) hydrogen phosphate and tris(4-methoxyphenyl) phosphate showed two emission bands. A long-wavelength emission band arose from the intramolecular excimer of two 4-methoxyphenyl groups and a short band arose from a 4-methoxyphenyl group itself. There was a good correlation between the relative intensity of the monomer/excimer emissions and the quantum yield of 4,4'-dimethoxybiphenyl, which was an intramolecular coupling product.