¹³C spin-lattice relaxation in rotationally disordered solids

Abstract

laC spin-lattice relaxation times and 14N linewidths at selected temperatures in liquid and solid I (plastic) succinonitrile are reported. Effective rotational correlation times are derived from these and the results for solid I are discussed in terms of a model which assumes that the main contributions to the rotational disorder come from gauche*-*trans isomerization and the jumping of the central C-C bond of the trans species between the 3-fold axes of the b.c.c, lattice. The general applicability of the 13C technique is emphasized and the results are compared with those of other experiments reported in the literature.

Fusion and solid-to-solid transitions of a homologous series of alkane-α,ω-dinitriles

“…Succinonitrile transition to the plastic crystal phase (table 4) has been extensively studied by calorimetry [2], nuclear magnetic resonance [37,38], X-ray and neutron scattering [39,40]. Our values for both T trs and D trs H are in very good agreement with those in the literature (table 3).…”

Rapid I−/I3− Diffusion in a Molecular‐Plastic‐Crystal Electrolyte for Potential Application in Solid‐State Photoelectrochemical Cells

“…[15][16][17][18][19][20]22] The bcc unit cell contains two molecules with the CÀC bonds oriented along the diagonals of the cube. [16,19,21,23] Below 233 K the molecules exist exclusively in the gauche conformation. [16,20] At 233 K the material undergoes a phase change to a plastic phase.…”

“…The disorder in this phase is related to trans-gauche isomerization (involving rotation about the central CÀC bond) of the molecules and molecular jumps from one diagonal position of the cubic structure to another. [19,23] Hawthorne and Sherwood suggested that the availability of three possible conformers in succinonitrile has a major effect on the diffusion capability of the molecules, whereby the trans isomers act as "impurities" that create monovacancies in the lattice [16,23] and hence lead to high molecular diffusivity. These properties triggered our interest in the concept of fast I À /I 3 À diffusion in a molecular plastic crystal.…”

Rapid I−/I3− Diffusion in a Molecular‐Plastic‐Crystal Electrolyte for Potential Application in Solid‐State Photoelectrochemical Cells

“…22 The bcc unit cell contains two molecules with the CC bonds oriented along the diagonals of the cube 16. 19, 21, 23 Below 233 K the molecules exist exclusively in the gauche conformation 16. 20 At 233 K the material undergoes a phase change to a plastic phase.…”