钆3TCAS2：一种具有极慢配体取代动力学的水合钆（3+）-硫杂杯[4]芳烃夹心簇合物。
Gd3TCAS2: An Aquated Gd(3+)-Thiacalix[4]arene Sandwich Cluster with Extremely Slow Ligand Substitution Kinetics.
作者信息
Iki Nobuhiko, Boros Eszter, Nakamura Mami, Baba Ryo, Caravan Peter
机构信息
Graduate School of Environmental Studies, Tohoku University , 6-6-07 Aramaki-Aoba, Aoba-ku, Sendai 980-8579, Japan.
A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School , 149 13th Street, Suite 2301, Charlestown, Massachusetts 02129, United States.
出版信息
Inorg Chem. 2016 Apr 18;55(8):4000-5. doi: 10.1021/acs.inorgchem.6b00241. Epub 2016 Mar 28.
In aqueous solution, Gd(3+) and thiacalix[4]arene-p-tetrasulfonate (TCAS) form the complex Gd3TCAS2, in which a trinuclear Gd(3+) core is sandwiched by two TCAS ligands. Acid-catalyzed dissociation reactions, as well as transmetalation and ligand exchange with physiological concentrations of Zn(2+) and phosphate, showed Gd3TCAS2 to be extremely inert compared to other Gd complexes. Luminescence lifetime measurements of the Tb analogue Tb3TCAS2 allowed estimation of the mean hydration number q to be 2.4 per Tb ion. The longitudinal relaxivity of Gd3TCAS2 (per Gd(3+)) was r1 = 5.83 mM(-1) s(-1) at 20 Hz (37 °C, pH 7.4); however, this relaxivity was limited by an extremely slow water exchange rate that was 5 orders of magnitude slower than the Gd(3+) aqua ion. Binding to serum albumin resulted in no relaxivity increase owing to the extremely slow water exchange kinetics. The slow dissociation and water exchange kinetics of Gd3TCAS2 can be attributed to the very rigid coordination geometry.
在水溶液中，钆（Ⅲ）与对四磺酸硫杂杯[4]芳烃（TCAS）形成配合物[Gd₃TCAS₂]⁷⁻，其中一个三核钆（Ⅲ）核心夹在两个TCAS配体之间。酸催化解离反应，以及与生理浓度的锌（Ⅱ）和磷酸盐的金属转移和配体交换表明，与其他钆配合物相比，[Gd₃TCAS₂]⁷⁻极其惰性。对铽类似物Tb₃TCAS₂的发光寿命测量使得能够估计每个铽离子的平均水合数q为2.4。[Gd₃TCAS₂]⁷⁻（每个钆（Ⅲ））在20 Hz（37℃，pH 7.4）下的纵向弛豫率为r₁ = 5.83 mM⁻¹ s⁻¹；然而，这种弛豫率受到极慢的水交换速率的限制，该速率比钆（Ⅲ）水合离子慢5个数量级。由于极慢的水交换动力学，与血清白蛋白结合不会导致弛豫率增加。[Gd₃TCAS₂]⁷⁻缓慢的解离和水交换动力学可归因于非常刚性的配位几何结构。
Zotero 插件