Journal of Physical Chemistry B, Vol.101, No.20, 3937-3944, 1997
H-1-)P-31, P-31-)H-1, and H-2-)H-1 CP/MAS NMR-Studies of the Large-Pore Gallophosphate Molecular-Sieve Cloverite
Air-equilibrated cloverite containing normal and deuterated water was studied by H-1, P-31, and Ga-71 NMR with magic-angle spinning (MAS). The spectra are assigned, and the H-1 and P-31 spin-lattice relaxation and the kinetics of H-1 --> P-31, P-31, H-1, and H-2 --> H-1 cross-polarization (CP) are examined in detail. Spin diffusion between the observed spins (H-1 or P-31) has a significant effect on the relative intensities of lines in the CP spectra. The results indicate that cloverite contains water-rich and water-deficient microdomains that contribute separately to the overall spectra. The water-rich microdomains contain defect P-OH groups created by the hydrolysis of the Ga-O-P bonds.
Keywords:SOLID-STATE NMR;NUCLEAR-MAGNETIC-RESONANCE;CROSS-POLARIZATION NMR;MAGIC-ANGLE;SPIN DIFFUSION;SPECTROSCOPY;POLYMERS;QUADRUPOLAR;RELAXATION;SPECTRA