29Si labelled nanoaluminosilicate imogolite

Imogolite is an interesting non-crystalline aluminosilicate adsorbant. Fused 29Si sodium silicate and aluminum perchlorate has been used to synthesis 29Si labelled imogolite from 29Si labelled SiO2. The product imogolite has interesting NMR and infrared spectroscopic properties because of the location of 29Si as isolated silicon tetrahedra but still near neighbors. Infrared absorptions differ from those in unlabelled material due to lower vibrational bond energy and multiple protonation equilibria. 29Si linewidths in solid state NMR spectra are dominated by 29Si–27Al heteronuclear dipolar interactions so homonuclear 29Si–29Si J or dipolar coupling is not seen. Nevertheless by undertaking static and decoupling experiments it was possible to measure the 29Si–29Si dipolar interaction as about 82 Hz. Since the nature of dipolar charges affects the capacity of a surface to adsorb molecules the magnitude of the dipolar interactions affects the capacity of imogolite to adsorb polar molecules as well as on its surface.