Inelastic neutron scattering study of the coordination of para-amino benzoic acid molecules to the surface of nanocrystalline titania particles

The interaction of para-amino benzoic acid (PABA) with nanocrystalline titania particles has been studied with inelastic neutron scattering. The vibrational spectra of hybrid TiO2/PABA, with different amounts of PABA, are compared with the spectrum obtained for solid PABA and to spectra derived from ab initio calculations for the isolated and dimer molecules. The absence of the OH bending modes of the carboxylic acid group for the chemisorbed species supports the formation of Ti–O–C bonds with the carboxyl group of the molecule.