RAMAN-SPECTROSCOPIC INVESTIGATION OF THE PHYSICAL STATE OF PARA-NITROANILINE IN CHANNELS OF THE ALPO4-5 MOLECULAR-SIEVE

The physical state of para-nitroaniline (p-NA) adsorbed in the channel s of AlPO4-5 molecular sieves has been investigated by means of Raman spectroscopy. The Raman spectra show that the p-NA molecules within th e channels form either a phase of head-to-tail chains similar to that in the solid crystaline p-NA with a characteristic omega3 band at 1282 cm-1 or a second phase, which is characterized by the similarly stron g band around 1295 cm-1. This second phase consists of weakly interact ing p-NA molecules in a similar pseudo-quinonoidic state as molten p-N A. Despite the missing formation of solid-like chains, molecules in th e second phase are also highly orientated. However, their mean nutatio n angle with respect to the crystal axis z is about 16-degrees, and, t hus, it is larger than that of the chains.