Yang Luqin, la Cour Agnete, Anderson Oren P, Crans Debbie C
Department of Chemistry, College of Natural Sciences, Colorado State University, Fort Collins, Colorado 80523, USA.
Inorg Chem. 2002 Dec 2;41(24):6322-31. doi: 10.1021/ic0201598.
The aqueous solution and solid state properties of (4-hydroxypyridine-2,6-dicarboxylato)dioxovanadate(V) (also referred to as (4-hydroxydipicolinato)dioxovanadate(V) or (chelidamato)dioxovanadate(V) and abbreviated VO(2)(dipic-OH)) were investigated. By using (1)H, (13)C, (17)O, and (51)V NMR 1D and 2D spectroscopy, the species present in solution, together with pK(a) values, equilibrium constants, and labilities, were characterized. The complex is most stable at acidic pH down to pH 1 where it is protonated. The stability of this complex is higher than that of the parent dipicolinatodioxovanadate(V) complex. The dipic-OH ligand is coordinated in a tridentate manner throughout the pH range studied, and the vanadium(V) atom is five-coordinate. Solid state structures of (NMe(4))[VO(2)(dipic-OH)].H(2)O (monoclinic, P2(1)/n) and Na[VO(2)(dipic-OH)].2H(2)O (triclinic, P1) were determined. The discrete complex anions in (NMe(4))[VO(2)(dipic-OH)].H(2)O are connected by hydrogen bonding between the hydroxyl group, a water molecule, and a carboxylate oxygen atom. Changing the counterion from NMe(4)(+) to sodium ion in Na[VO(2)(dipic-OH)].2H(2)O leads to the formation of a polymeric structure. Dynamic processes in solution were explored by using (1)H and (13)C EXSY NMR spectroscopy; exchange between complex and free ligand below pH 4 was observed. The differences between the dipicolinatodioxovanadate(V) parent complex and the VO(2)(dipic-OH) complex in the solid state and in solution demonstrate the subtle consequences of the one substitutional difference between the two ligands. The insulin-mimetic properties of this compound are likely to be of mechanistic interest in developing an understanding of the mode of action of the few known insulin-mimetic vanadium(V) complexes.
研究了（4-羟基吡啶-2,6-二羧酸根）二氧钒（V）（也称为（4-羟基吡啶二甲酸根）二氧钒（V）或（白屈菜酸根）二氧钒（V），缩写为[VO₂(dipic-OH)]⁻）的水溶液和固态性质。通过使用¹H、¹³C、¹⁷O和⁵¹V NMR一维和二维光谱，对溶液中存在的物种以及pKₐ值、平衡常数和活性进行了表征。该配合物在低至pH 1的酸性pH条件下最稳定，此时它被质子化。该配合物的稳定性高于母体吡啶二甲酸根二氧钒（V）配合物。在整个研究的pH范围内，dipic-OH配体以三齿方式配位，钒（V）原子为五配位。测定了（NMe₄）[VO₂(dipic-OH)]·H₂O（单斜晶系，P2₁/n）和Na[VO₂(dipic-OH)]·2H₂O（三斜晶系，P1）的固态结构。（NMe₄）[VO₂(dipic-OH)]·H₂O中的离散配合物阴离子通过羟基、水分子和羧酸根氧原子之间的氢键相连。在Na[VO₂(dipic-OH)]·2H₂O中将抗衡离子从NMe₄⁺变为钠离子会导致形成聚合物结构。通过使用¹H和¹³C EXSY NMR光谱研究了溶液中的动态过程；观察到在pH 4以下配合物和游离配体之间的交换。吡啶二甲酸根二氧钒（V）母体配合物与[VO₂(dipic-OH)]⁻配合物在固态和溶液中的差异表明了两种配体之间一个取代差异的微妙影响。该化合物的胰岛素模拟特性可能在深入了解少数已知的胰岛素模拟钒（V）配合物的作用模式方面具有机制研究意义。
