NMR Studies on Interactions between Diperoxovanadate and 1-Ethyl-1H-Imidazole

为探讨过氧钒配合物中有机配体对反应平衡的影响,在模拟生理条件下(0.15MOl·l-1nACl溶液),应用多核(1H、13C和51V)多维(COSy和HSQC)核磁共振(nMr)以及变温技术等谱学方法研究双过氧钒配合物[OV(O2)2l]-(l=d2O或HOd,与之配位的过氧钒物种简写为bPV)和[OV(O2)2ll′]n{-n=1-2,ll′=3-羟基-皮考啉酸根(3-OH-PIC),2-(2′-吡啶)-咪唑(Py-IM),1,10-邻菲啰啉(PHEn),与它们配位的含钒物种分别简写为bPV(3-OH-PIC)、bPV(Py-IM)和bPV(PHEn)}与n-乙基咪唑(n-ET-IM)的相互作用.实验结果表明,n-ET-IM与4种双过氧钒配合物反应性从强到弱的顺序为bPV>bPV(3-OH-PIC)>bPV(Py-IM)>bPV(PHEn).研究表明,金属中心上配体的配位能力、空间位阻和分子量等因素都对反应平衡产生较大的影响,同时竞争配位的结果导致新的6配位过氧物种[OV(O2)2(n-ET-IM)]-的生成.利用上述谱学方法有助于揭示此类相互作用体系的反应过程和配位方式.To understand the effects of organic ligands on the reaction equilibrium, interactions between a series of diperoxovanadate complexes [OV(O2)2L]- (L=D2O or HOD, the corresponding peroxovanadate species (bpV)) and [OV (O2)2LL′]n-{n=1-2; LL′ =3-hydroxyl-picolinate (3-OH-pic), 2-(2′-pyridine)-imidazole (py-im), 1,10-phenanthroline (phen), the corresponding peroxovanadate species bpV(3-OH-pic), bpV(py-im), and bpV(phen)}and 1-ethyl-1H-imidazole (N- Et-im) in solution were explored using multinuclear (1H, 13C, and 51V) magnetic resonance, COSY (correlated spectroscopy), HSQC (heteronuclear single quantum coherence) and variable temperature nuclear magnetic responance (NMR) using 0.15 mol·L-1 NaCl ionic medium to mimic physiological conditions.Experimental results indicated that the reactivity of these four complexes with 1-ethyl-1H-imidazole decreased as follows: bpV>bpV(3-OH-pic)>bpV(py-im)> bpV(phen).The coordinating ability, the steric effect, and the molecular weight of these organic ligands affected the reaction equilibrium.A new six-coordinated peroxovanadate species [OV(O2)2(N-Et-im)]- was formed because of competitive coordination.国家自然科学基金(20772027;20803020);中国博士后科学基金(20070410805);卫生部科学研究基金-福建省卫生教育联合攻关计划(WKJ2008-2-036);厦门市重大疾病攻关研究基金(3502Z20051027)资助项目---

NMR Studies on Interactions between Diperoxovanadate and 1-Ethyl-1H-Imidazole

To understand the effects of organic ligands on the reaction equilibrium, interactions between a series of diperoxovanadate complexes [OV(O-2)(2)L](-) (L=D2O or HOD, the corresponding peroxovanadate species (bpV)) and [OV (O-2)(2)LL'](n-) {n=1-2; LL' =3-hydroxyl-picolinate (3-OH-pic), 2-(2'-pyridine)-imidazole (py-im), 1,10-phenanthroline (phen), the corresponding peroxovanadate species bpV(3-OH-pic), bpV(py-im), and bpV(phen)} and 1-ethyl-1H-imidazole (N-Et-im) in solution were explored using multinuclear (H-1, C-13, and V-51) magnetic resonance, COSY (con-elated spectroscopy), HSQC (heteronuclear single quantum coherence) and variable temperature nuclear magnetic responance (NMR) using 0.15 mol.L-1 NaCl ionic medium to mimic physiological conditions. Experimental results indicated that the reactivity of these four complexes with 1-ethyl-1H-imidazole decreased as follows: bpV > bpV(3-OH-pic)> bpV(py-im)> bpV(phen). The coordinating ability, the steric effect, and the molecular weight of these organic ligands affected the reaction equilibrium. A new six-coordinated peroxovanadate species [OV(O-2)(2)(N-Et-im)](-) was formed because of competitive coordination.National Natural Science Foundation of China [20772027, 20803020]; China Postdoctoral Science Foundation [20070410805]; Science Research Foundation of Ministry of Health & United Fujian Provincial Health ; Education Project for Tackling the Key Research [WKJ2008-2-036]; Health and Science and Technology of Xiamen, China [3502Z20051027

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