C-13 AND P-31 MAGIC-ANGLE-SPINNING NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY OF TRIS(2,3-NAPHTHALENEDIOXY)CYCLOTRIPHOSPHAZENE INCLUSION-COMPOUNDS

The inclusion compounds of tris(2,3-naphthalenedioxy)cyclotriphosphaze ne (TNP) with several small molecules have been studied, for the first time, by C-13 magic-angle spinning (MAS) NMR. The channel-type struct ure of TNP inclusion compounds (ICs) with benzene (and tetrahydrofuran , THF), and the cage-type structure of TNP ICs with p-xylene has been associated with the multiplicity of the C-13 signals due to each carbo n atom in the unit cell. Bending of the large paddles of the TNP matri x was established on the basis of the chemical shifts. The release of the guest molecules has been followed by differential scanning calorim etry and by solid-state NMR. The C-13 cross-polarization (CP) MAS spec trum of guest-free TNP structure has been interpreted in accordance wi th the formation of the monoclinic cell. P-31 CP MAS spectra reflect t he symmetry of the crystal cell. A residual dipolar coupling with N-14 is also observed. The dynamic behavior of the guest and host molecule s has been studied by the measument of C-13 T-1 relaxation times. The high mobility of benzene molecules is transferred to the host structur e, which presents shorter relaxation times than the guest-free TNP sys tem. The triethylammonium tris(2,3-naphthalenedioxy)phosphate obtained as a byproduct from the synthesis has also been characterized by C-13 and P-31 CP MAS.