Laser-induced fluorescence of quinoline adsorbed on acidic zeolites

Laser-induced fluorescence spectra of quinoline adsorbed on different forms of acidic Y zeolite reveal interactions between the adsorbate and different polarizing sites in the supercages. Brّnsted acid sites protonate quinoline whereas Lewis acid sites appear to give a charge-transfer complex whose fluorescence is strongly red-shifted compared to that of the quinolinium ion. An unstable hydrogen-bonded complex is formed with non-acidic silanol groups.