The Effect of Chemical Exchange on Energy and Phase Relaxation-Processes in Nuclear Magnetic Resonance Spectroscopy

用核磁共振和同位素取代法研究了离子溶液中化学交换反应的动力学和平衡性质，以及离子溶液中的局域原子排列。利用A位和B位纵向磁化强度随时间演化的耦合表达式的通解，考察了化学交换对核磁共振纵向磁化恢复曲线和核磁共振谱中线形的影响。(1)Al_2(SO_4)_3水溶液中的配体交换反应[Al(H_2O)_6]^&lt；3+&gt；+SO^2-&lt；双箭[Al(H_2O)_5SO_4][Al(H_2O)_5SO_4]++H_2O和(2)氯铝酸盐熔体中不同络合物种之间的交换反应。用~(25)P和~(31)P核磁共振研究了~lt；~(25)P和~(31)P~(2+)在ATP中与~lt；BATA&P-磷结合的两个非桥氧基团的几何构型及其与ATP的相互作用。(3)在水溶液中，被水分子从ATP中分离出来的与ATP结合的Mg~(2+)和失去第一配位球中的水分子的紧密结合的Mg~(2+)和Gt~(2+)之间可能发生交换反应。阐明了它们之间可能的构象以及Li~(2+)的络合离子可能的配位作用。

The studies on the kinetic and equilibrium properties of chemical exchangereaction, and local atomic-arrangement in the ionic solutions were carried out by using nuclear magnetic resonance and isotopic substitution methods.We have investigated the influence of chemical-exchange on the line-shapes in the NMR longitudinal magnetization recovery curves as well as in the NMR spectra by using a general solution of the coupled expressions for the time evolution of the longitudinal magnetizations of sites A and B. (1) The ligand exchange-reaction in aqueous Al_2(SO_4)_3 solution[Al(H_2O)_6]^<3+>+so^2-_<double arrow> [Al(H_2O)_5SO_4]^+ + H_2O and (2) the exchange-reaction between different complex-species in chloroaluminate melts2Alc1^-_ <double arrow> Al_2C1^-_ + Cl^-was characterized about their kinetic and equilibrium properties by using ^<27>Al NME. The ^<25>Mg and ^<31>P nuclear magnetic resonance was applied to a study of geometry of Mg^<2+> around two non-bridging oxygens binding to <bata>-phosphorus in ATP and interaction of Mg^<2+> with ATP. (3) The exchange reaction in aqueous ATP + Mg^<2+> solution may take place between ATP-bound Mg^<2+> separated from ATP by a water molecule and tightly site-bound Mg^<2+> which loses the water molecule from the first coordination sphere.The structures of molten LiAlCl_4 and LiNO_3 have been investigated by means of neutron diffractometer, using the method of Li and N isotopic substitution. The possible conformation among them as well as the possible coordination by complex ion of Li^+ was illustrated.