Department of Chemistry, Portland State University, 1719 SW 10th Ave, Portland, OR 97201, USA.
Dalton Trans. 2014 Jan 7;43(1):251-8. doi: 10.1039/c3dt52143e.
Coordination exchange processes tend to dominate the solution state behaviour of lanthanide chelates and generally prohibit the study of small conformational changes. In this article we take advantage of coordinatively rigid Eu(3+) chelates to examine the small conformational changes that occur in these chelates as water dissociatively exchanges in and out of the inner coordination sphere. The results show that the time-averaged conformation of the chelate alters as the water exchange rate increases. This conformational change reflects a change in the hydration state (q/r(LnH)(6)) of the chelate. The hydration state has recently come to be expressed as two separate parameters q and r(LnH). However, these two parameters simultaneously describe the same structural considerations which in solution are indistinguishable and intrinsically related to, and dependent upon, the dissociative water exchange rate. This realization leads to the broader understanding that a solution state structure can only be appreciated with reference to the dynamics of the system.
配位交换过程往往主导镧系配合物在溶液中的行为，通常会阻碍对小分子构象变化的研究。在本文中，我们利用配位刚性的 Eu(3+) 配合物来研究当水在配合物的内配位球中不断进行离解和配位时发生的小分子构象变化。结果表明，随着水交换速率的增加，配合物的时间平均构象发生改变。这种构象变化反映了配合物的水合状态（q/r(LnH)(6)）发生了变化。水合状态最近被表示为两个独立的参数 q 和 r(LnH)。然而，这两个参数同时描述了相同的结构考虑因素，这些结构在溶液中是不可区分的，并且与离解水交换速率内在相关并依赖于它。这种认识导致了更广泛的理解，即只有参考体系的动力学，才能理解溶液状态的结构。
