Studies of adsorption of 2,2′-bipyridyl on the surface of highly regulated silica matrix of the MCM-41 type by means of 15N NMR spectroscopy

Abstract

The study of 2,2′-bipyridyl adsorption on the surface of highly regular MCM-41 silica at 300 and 130 K was carried out by the 15N NMR spectroscopy. It was shown that at 300 K the adsorbed molecules were involved in the processes of isotropic reorientation accompanied by the formation and rupture of hydrogen bonds with the surface-located hydroxy groups. Each molecule of 2,2′-bipyridyl forms no more than one hydrogen bond at a time, and their surface density is about one molecule per 1 nm2 of the surface. At 130 K 2,2′-bipyridyl forms a monolayer on the surface of silica including about 1.6 molecule per 1 nm2. In this monolayer each molecule forms a hydrogen bond with one hydroxy group and prevents the interaction of the other bipyridyl molecules with one more hydroxy group.