SELF-DECOUPLING OF N-15-N-14 DIPOLE-QUADRUPOLE COUPLINGS IN N-15 CPMAS NMR-SPECTRA AND MOLECULAR MOTIONS IN CRYSTALLINE HYDRAZINE SULFATE, P-(DIETHYLAMINO)BENZALDEHYDE DIPHENYLHYDRAZONE, AND ITS SOLID-SOLUTIONIN POLYCARBONATE

Self-decoupling of N-15-N-14 dipole-quadrupole couplings was studied b y variable temperature N-15 CPMAS line-shape analysis of singly N-15-l abeled hydrazine sulfate and (diethylamino)benzaldehyde diphenylhydraz one in various solid phases. This phenomenon is caused by molecular mo tions leading to fast N-14 longitudinal relaxation. In the crystalline room temperature phase of hydrazine sulfate, these motions are identi fied as 180 degrees jumps of hydrazonium perpendicular to the NN-axis. p-(Diethylamino)benzaldehyde diphenylhydrazone (DEH) is used as a cha rge transport agent in organic layered photoconductors. In the crystal line state of this compound, no self-decoupling is observed; in contra st, self-decoupling is observed in solid solutions of DEH in bisphenol A polycarbonate (PC), indicating the presence of molecular motions ca using fast N-14 longitudinal relaxation. We assign these motions to an internal mobility of the phenyl groups of DEH in the glassy solution, The N-15 CPMAS NMR line shapes are interpreted in terms of a broad di stribution of activation energies of the motions.