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. [Display omitted] •FTIR spectra provide detailed information about niflumic acid aggregation.•Bands of carbonyl groups are sensitive to dimerization or H-bonding on adsorption.•Mutual arrangement of dimers in solids is reflected in the bands of CF vibrations.•Aggregation does not shift the maximum of luminescence but increases the intensity.