高浓度配体低浓度顺磁离子体系NMR的顺磁弛豫研究(Ⅱ)——配体脱离顺磁离子后1/T_2变化过程的研究

Studies on the Paramagnetic Relaxation in the Solution with a few of Paramagnetic Ions and a lot of Ligands(Ⅱ)

本文首先指出高浓度配体低浓度顺磁离子体系(L+M)中未配位的配体的横向弛豫速率1/T_2(?)与未加任何顺磁离子的配体的1/T_2(?)不一样是由于配体脱离顺磁离子后1/T_2有一个变化过程所致,并着重研究了此过程中1/T_2的变化规律。通过曲线拟合的方法从实验上证实了有关变化规律的研究。在拟合过程中估计出了完全排除交换效应后顺磁离子对配体弛豫影响的1/T_2(?)或1/G_(?)因此由S-B方程可求得顺磁离子与各碳原子间的距离,可确定络合物的空间构象,从而首次建立了应用顺磁弛豫增宽法来确定络合物空间构象的方法。这具有重要的理论意义和应用价值。

A new explanation of the broadening of NMR peaks of the solution with a few of paramagnetic ions and a lot of ligands is reported in the paper. The new points about the explanation have been proveo true in the experiment. In the course of the prove, the value of 1/G_1 or 1/T_(21) have been calculated. Because 1/G_1 or 1/T_(21) gets rid of the effect of the exchange between ligands, the distance between paramagnetic ions and carbonic atoms of ligands can be caculaed with 1/G_1 or 1/T_(21) by means of S-B equation. So contiguration of the complexes can be gained.