Allosteric binding of alkali metal ions to a pseudo-cryptand formed by a C-pivot tripodal ligand containing 3-hydroxy-2(1H)-pyridinone and Ga(III)
Allosteric binding of alkali metal ions to a pseudo-cryptand formed by a C-pivot tripodal ligand containing 3-hydroxy-2(1H)-pyridinone and Ga(III)
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DOI：
10.3987/com-05-s(k)20
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发表时间：
2005-12-31
期刊：
影响因子：
0.6
通讯作者：
Saito, R
中科院分区：
文献类型：
--
作者：
Katoh, A;Kudo, H;Saito, R
以3-羟基-2(1H)-吡啶酮为双齿配体，乙氧基链为间隔基，三(羧酸)为锚链，合成了一种新型的C轴三脚六齿配体(3，2-HOPOHL)。3，2-HOPOHL只识别Na+离子，这表明它由于2(1H)-吡啶酮环之间的静电相互作用而预先组织了一个空穴。UV-Vis光谱分析表明，3，2-HOPOHL在水溶液中形成稳定的分子内1：1 Fe(III)络合物。3，2-HOPOHL-Fe(III)络合物与EDTA竞争反应的稳定常数(LogK)为27.6。3，2-HOPOHL-Ga(III)与Na+、K+离子在CDCl3-CD3CN中的H-1-核磁共振滴定表明形成了1：1的络合物。测得Na+和K+-3，2-HOPOHL-Ga(III)络合物的结合常数分别为3.3×10~(3)M~(-1)和7.8×10~(3)M~(-1)，K~+对Na~+的离子选择性大于2倍。
A novel C-pivot tripodal hexadentate ligand (3,2-HOPOHL) composed of 3-hydroxy-2(1H)-pyridinone as a bidentate ligand, the ethyleneoxy chain as a spacer, and tris(carboxyric acid) as an anchor was synthesized. 3,2-HOPOHL recognized only Na+ ion, suggesting that it pre-organized a cavity due to the electrostatic interaction among the 2(1H)-pyridinone rings. UV-VIS spectroscopic analysis indicated that 3,2-HOPOHL formed a stable intramolecular 1:1 Fe(III) complex in aqueous solution. The stability constant (log K) of 3,2-HOPOHL-Fe(III) complex was estimated to be 27.6 from the competitive reaction with EDTA. H-1-NMR titration of 3,2-HOPOHL-Ga(III) complex with Na+ and K+ ions in CDCl3-CD3CN indicated the formation of 1:1 complexes. The binding constants of Na+- and K+-3,2-HOPOHL-Ga(III) complexes were estimated to be 3.3x10(3) and 7.8x10(3) M-1, respectively, the ion selectivity of K+ toward Na+ being more than two-fold.