Spectral studies of niflumic acid aggregation in dissolved, solid and adsorbed states

FTIR spectra of niflumic acid in solid state, dissolved in CCl₄ and adsorbed on silica or alumina surface, as well as their temperature dependence, provide information about different stages of aggregation: monomers, dimers, amorphous and crystalline solid phase, as well as about perturbation of the molecule by the surface. The spectra observed are compared with those obtained by quantum mechanical calculations. The luminescence spectra are less sensitive to the aggregation, they differ mostly in the intensity, while the position of maximum at about 440 nm remains almost the same.