Andrew E R, Peplinska B
Department of Physics, University of Florida, Gainesville 32611, USA.
Solid State Nucl Magn Reson. 1998 Nov;13(1-2):39-43. doi: 10.1016/s0926-2040(98)00076-9.
An investigation of the molecular dynamics of all-trans retinoic acid (vitamin A) has been carried out in the solid state by proton NMR. Measurements were made of T1 at 14 and 25 MHz and of second moment at 25 MHz in the temperature range 55 to 420 K for both monoclinic and triclinic forms. In the monoclinic state relaxation was attributed to methyl group reorientation below 250 K and to conformational motion of the cyclohexene ring above this temperature. Activation energies and time constants were derived for the motions. In the triclinic state the same motions were active, but the cyclohexene ring motion was less restricted and some of the methyl group motions were more restricted indicating that hindrances to the motions were at least partly determined by the intermolecular packing arrangements.
通过质子核磁共振对全反式维甲酸（维生素A）在固态下的分子动力学进行了研究。在55至420K的温度范围内，对单斜晶和三斜晶形式的样品分别在14MHz和25MHz下测量了T1，并在25MHz下测量了二阶矩。在单斜晶态中，低于250K时弛豫归因于甲基的重取向，高于此温度时归因于环己烯环的构象运动。推导了这些运动的活化能和时间常数。在三斜晶态中，相同的运动也存在，但环己烯环的运动受限较小，而一些甲基的运动受限较大，这表明运动的阻碍至少部分由分子间堆积排列决定。
