A novel 24-membered macrocyclic compound having two hydroxyethyl pendants L, 3,6,9,17,20,23-hexazatricyclo[23.3.1.1.11,15]triconta-1(29),11(30),12,14,25,27-hexaene-6,20-bis(2-hydroxyethyl), has been synthesized as a dinucleating ligand. A new complex [Zn2H−2L]Br2(H2O)2 has been synthesized as a model to mimic the active center of alkaline phosphatase. The bridging coordination of the two alkoxides to two ZnII ions was confirmed by the crystal structure of [Zn2H−2L]Br2(H2O)2. The protonation constants of L as well as complexation constants of L with ZnII have been determined at 298.1 K by means of potentiometric titration. [Zn2H−2L]2+ and [Zn2H−2L(OH)]+ are the dominant species in aqueous solution at 7 < pH < 9. The kinetics of promoted hydrolysis of p-nitrophenyl acetate has also been studied; the second-order rate constant is 0.018 M−1 s−1 at pH = 9.0.
我们合成了一种新型 24 元大环化合物,它具有两个羟乙基垂体 L,即 3,6,9,17,20,23-六氮杂
三环[23.3.1.1.11,15]三
蒽-1(29),11(30),12,14,25,27-六烯-6,20-双(2-羟乙基),作为一种二核化
配体。我们合成了一种新的复合物 [Zn2H-2L]Br2(
H2O)2 作为模拟碱性
磷酸酶活性中心的模型。[Zn2H-2L]Br2( )2的晶体结构证实了两个烷氧基与两个ZnII离子的桥式配位。在 298.1 K 的温度下,通过电位滴定法测定了 L 的质子化常数以及 L 与 ZnII 的络合常数。在 7 < pH < 9 的条件下,[Zn2H-2L]2+ 和 [Zn2H-2L(OH)]+ 是水溶液中的主要物种。还研究了对硝基苯乙酸酯的促进
水解动力学;在 pH = 9.0 时,二阶速率常数为 0.018 M-1 s-1。