取代吡啶与双过氧钒配合物相互作用的NMR和理论研究

为探讨有机配体上取代基团对反应平衡的影响, 在模拟生理条件下(0.15 mol/L NaCl溶液), 应用多核(1H, 13C和51V)多维(DOSY)以及变温NMR技术研究双过氧钒配合物[OV(O2)2(D2O)]－/[OV(O2)2(HOD)]－(简写为bpV)与取代吡啶的相互作用. bpV与有机配体的反应性从强到弱的顺序为: 皮考林酸根＞异烟酸根＞异烟酸甲酯＞皮考林甲酯, 这说明吡啶环上同一位置上的不同取代基团和同一取代基团在不同位置上都影响反应平衡, 竞争配位导致一系列新的6配位(配体为异烟酸根和异烟酸甲酯)或7配位(配体为皮考林酸根和皮考林甲酯)的过氧钒物种[OV(O2)2L]n－ (L＝取代吡啶, n＝1或2)生成, 密度泛函计算结果较合理地解释了实验结果, 并表明溶剂化在反应中起重要作用.     

双过氧钒配合物与N-乙基咪唑相互作用的NMR研究

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(0.15 mol·L-1 NaCl 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.     

双过氧钒配合物与3-取代吡啶相互作用的NMR研究

为探讨有机配体上取代基团对反应平衡的影响, 在模拟生理条件下(0.15 mol/L NaCl溶液), 应用多核(1H、13C和51V)多维(DOSY)以及变温NMR技术研究双过氧钒配合物[OV(O2)2(D2O)]－/[OV(O2)2(HOD)]－(简写为dpV)与3-取代吡啶的相互作用, 并首次报道了一些物种的NMR化学位移. dpV与有机配体的反应性从强到弱的顺序为: 吡啶＞烟酸 根＞烟酸甲酰胺≈烟酸甲酯, 这说明吡啶环上取代基影响反应平衡. 竞争配位导致一系列新的6配位的过氧钒物种生成. 密度泛函计算结果合理地解释了实验结果, 并表明溶剂化效应在反应中起重要作用.     

双过氧钒配合物与吡啶类配体相互作用的NMR研究

为探讨单齿/双齿吡啶类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,HSQC和HMBC)以及变温NMR技术研究双过氧钒配合物[OV(O2)2(D2O)]-/[OV(O2)2(HOD)]-(简写为bpV)与系列吡啶类配体的相互作用,研究结果表明bpV与有机配体的反应性从强到弱的顺序为:2,2′-联吡啶2,2′-联吡啶-4,4′-二甲酸根吡啶异烟酸根,这说明双齿吡啶类配体配位能力强于单齿配体,而不带羧基的吡啶类配体(单齿或双齿)配位能力强于所对应的带羧基的取代吡啶,竞争配位导致一系列新的6配位(配体为吡啶或异烟酸根)或7配位(配体为2,2′-联吡啶或2,2′-联吡啶-4,4′-二甲酸根)的过氧钒物种[OV(O2)2LL′]n-(LL′=吡啶类配体,n=1,2,3)生成。     

草酸双过氧钒配合物与有机配体相互作用的NMR和ESI－MS研究

应用~1H, ~(13)C和~(51)V多核NMR技术和电喷雾质谱等谱学手段研究草酸双过 氧钒配合物与吡啶、4－甲基咪唑、咪唑等有机配体的相互作用。研究发现：这些 相互作用都生成过氧钒物种[OV(O_2)_2L]~-（L为有机配体），其从易到难的顺序 为咪唑＞4－甲基咪唑＞吡啶。当配体为4－甲基咪唑时，产物是一对未见报道的异 构体。研究结果表明：将NMR技术和电喷雾质谱有机结合是研究此类体系切实可行 的方法，有助于提示钒化合物与有机配体相互作用的规律和机制。     

双过氧钒配合物与N-取代皮考啉酰胺相互作用的NMR研究

为了探讨有机配体上取代基团对反应平衡的影响, 在模拟生理条件下(0.15 mol/L NaCl溶液), 应用多核(¹H, ¹³C和⁵¹V)多维(COSY和DOSY) NMR以及变温技术等谱学方法研究双过氧钒配合物[OV(O₂)₂(D₂O)]⁻/[OV(O₂)₂(HOD)]⁻与N-取代皮考啉酰胺的相互作用. 它们反应性从强到弱的顺序为: N-甲基-皮考啉酰胺≈N-(2-羟乙基)-皮考啉酰胺＞N-乙基-皮考啉酰胺＞N-丙基-皮考啉酰胺, 这说明了皮考啉酰胺N上取代基的电子效应影响反应. 竞争配位导致一系列新的7配位的过氧钒物种生成, 而利用上述谱学方法则有助于揭示此类相互作用体系的反应过程和配位机制.     

NMR研究N-甲基咪唑与双过氧钒配合物的相互作用

为探讨过氧钒配合物上有机配体对反应平衡的影响, 在模拟生理条件下(0.15 mol/L NaCl溶液), 应用多核(¹H, ¹³C和⁵¹V)多维(COSY) NMR以及变温技术等谱学方法研究双过氧钒配合物[OV(O₂)₂LL']ⁿ− [n＝1～3, LL'＝oxalate (缩写为oxa)、picolinate(缩写为pic)、bipyridine(缩写为bipy)和1,10-phenanthroline(缩写为phen), 与它们配位的含钒物种分别缩写为bpV(oxa), bpV(pic), bpV(bipy)和bpV(phen)]与N-甲基咪唑(缩写为N-Me-Im)的相互作用, 实验结果表明N-Me-Im与4种双过氧钒配合物的反应活性从强到弱的顺序为: bpV(oxa)＞bpV(pic)＞bpV(bipy)＞bpV(phen). 研究表明金属中心上配体的配位能力和空间位阻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过氧物种[OV(O₂)₂(N-Me-Im)]⁻的生成, 而利用上述谱学方法则有助于揭示此类相互作用体系的反应过程和配位方式.     

基于2-甲基-8-羟基喹啉的镝单分子磁体的晶体结构及磁性（英文）

以2-甲基-8-羟基喹啉(HL)为配体合成了2个含有镝离子的配位化合物[Dy2L4(HL)4(H2O)2](Cl O4)2·2H2O(1)和[Dy2L6(C2H5OH)]·H2O(2)。虽然在这两个配位化合物中配体都是2-甲基-8-羟基喹啉,但其参与配位的方式不同。这导致2个化合物中镝离子所处的配位环境不同,进而对化合物的磁性产生了影响。     

两个一维铜配位聚合物的合成、晶体结构及其与双氧水的氧化反应

本文利用柔性的N,N,N′,N′-间-二甲苯二胺四乙酸(H4L)及不同的氮杂环配体如刚性的4-4′-联吡啶(4,4′-bipy)及柔性的间-二(咪唑-1-亚甲基)苯(mbix)构筑了2个新的一维铜配位聚合物{[Cu2L(4,4′-bipy)(H2O)2].2.5H2O}n(1)和{[Cu2L(mbix)(H2O)2].3H2O}n(2),并对其进行了元素分析、红外光谱和X-ray单晶衍射表征。另外利用紫外-可见光谱的方法对2个化合物与H2O2的氧化反应进行了研究,结果表明虽然化合物1和2在高浓度的H2O2条件下均发生了分子断裂,但仍能使配体L4-中二甲苯基联接体C2位置发生羟基化。     

含咪唑基配体镉配位聚合物的合成、结构及荧光性质

利用柔性含咪唑基配体1,3,5-三(咪唑-1-甲基)苯(L)与硫酸镉在溶剂热条件下反应,通过反应条件控制得到了2个配位聚合物{[Cd(L)(EG)0.5(H2O)(SO4)]·EG·H2O}n(1)和[Cd(L)(EG)(SO4)]n(2)(EG=乙二醇)。并利用元素分析、红外光谱、X射线单晶衍射等方法对其进行了表征。配合物1中配体L连接Cd(Ⅱ)形成一维链状结构,而配合物2中配体L与Cd(Ⅱ)配位形成二维网状结构,并进一步通过硫酸根桥联形成三维结构。有趣的是,EG分子在配合物1中连接链内的2个Cd(Ⅱ),而在配合物2中作为端基与1个Cd(Ⅱ)配位,硫酸根离子在1中作为端基配位,而在2中则以桥联方式连接2个Cd(Ⅱ)。研究了配合物的荧光性质及其热稳定性。     

Interactions between Bioactive Diperoxovanadate Complexes and Imidazole： Insights into Their Solution Structures by NMR and ESI-MS

1 INTRODUCTION As a required metal for some enzymes such as haloperidases and nitrogenases, vanadium com- pounds are capable of having many biological acti- vities. Similar to inorganic phosphates, vanadium compounds activate the functions of a numb…     

Study of the coordination and solution structures for the interaction systems between diperoxidovanadate complexes and 4-(pyridin-2-yl)pyrimidine-like ligands

To understand the substitution effects of 4-(pyridin-2-yl)pyrimidine (pprd) on the coordination reaction equilibria, the interactions between a series of the pprd-like ligands and [OV(O(2))(2)(H(2)O)](-) or [OV(O(2))(2)(HOD)](-) or [OV(O(2))(2)(D(2)O)](-) (bpV) have been explored by a combination of multinuclear ((1)H, (13)C, and (51)V) magnetic resonance, heteronuclear single quantum coherence (HSQC) and variable temperature NMR in a 0.15 mol L(-1) NaCl D(2)O solution that mimics physiological conditions. The direct NMR data are reported for the first time. Competitive coordination interactions result in a series of new hepta-coordinated peroxidovanadate species [OV(O(2))(2)LL'](-) (LL' = pprd-like chelating ligands). The equilibrium constants for the products between bpV and the pprd-like ligands show that the relative affinity of the ligands is pprd ≈ 2-NH(2)-pprd > 2-Me-pprd > 2-Et-pprd > 4-(6-methylpyridin-2-yl)pyrimidine (abbr. 6'-Me-pprd). When the ligand is pprd, a pair of isomers (Isomer A and B) are observed in aqueous solution, which are attributed to the different types of coordination modes between the metal and the ligands, while the crystal structure of NH(4)[OV(O(2))(2)(pprd)]·2H(2)O has the same coordination structure as Isomer A. For substituted pprd ligands, however, only one type of structure (Isomer A or B ) is observed in solution. These results demonstrate that, when the aromatic ring has a substitution group, both the steric effect (from the alkyl) and hydrogen bonding (from the amine) can affect the coordination reaction equilibrium to prevent the appearance of either Isomer B in solution for the ligands 2-Me-pprd, 2-NH(2)-pprd, 2-Et-pprd, or Isomer A in solution for 6'-Me-pprd.     

NMR and theoretical study on the coordination and solution structures of the interaction between diperoxovanadate complexes and histidine-like ligands

To simulate the types of coordination and solution structures of the active site of haloperoxidases, the interaction systems between diperoxovanadate complexes [OV(O2)2L]n- (n = 1 or 3, L = oxalate or H2O) and a series of histidine-like ligands in solution have been studied by using 1D multinuclear (1H, 13C, and 51V) NMR, 2D diffusion ordered spectroscopy, and variable-temperature NMR in 0.15 mol/L NaCl ionic medium, representing the physiological conditions of human blood. Some direct NMR data are given for the first time. The reactivity among the histidine-like ligands is imidazole > 2-methylimidazole > carnosine approximately 4-methylimidazole > histidine. Competitive coordination interactions result in a series of new peroxovanadate species [OV(O2)2L']- (L' = histidine-like ligands). When the ligands are 4-methylimidazole, histidine, and carnosine, a pair of isomers have been observed, which are attributed to different types of coordination between vanadium atom and ligands. The results of density functional theory calculations provided a reasonable explanation on the relative reactivity of the histidine-like ligands and the molar ratios of isomers. Theoretical results signify the importance of the solvation effect for the reactivity and stability of the interaction systems.     

Multinuclear NMR spectroscopic and theoretical study on the interactions between diperoxovanadate complex and picoline-like ligands

To understand the substituting effects of organic ligands on the reaction equilibrium, the interactions between diperoxovanadate complex [OV(O(2))(2)(H(2)O)](-) and a series of picoline-like ligands in solution were explored using 1D multinuclear ((1)H, (13)C, and (51)V) magnetic resonance, 2D diffusion ordered spectroscopy (DOSY), and variable temperature NMR in 0.15 mol/l NaCl ionic medium for mimicking the physiological conditions. The order of reactive capability of the picoline-like ligands with [OV(O(2))(2)(H(2)O)](-) is found to be picolinamide>N-methylpicolinamide>methyl picolinate>ethyl picolinate approximately propyl picoliniate>isopropyl picolinate. The substituting group influences the reactivity by either steric effect or electron-donating effect. Competitive coordination interactions result in a series of new seven-coordinated peroxovanadate species [OV(O(2))(2)L](-) (L=picoline-like ligands). Their coordination ways were confirmed by density functional calculations.     

NMR studies on interactions between diperoxovanadate and picolinamide-like ligands

To understand the effects of picolinamide-like ligands on reaction equilibrium, a series of picolinamide derivatives were synthesized and the interactions between the diperoxovanadate complex [OV(O₂)₂L]^? (L = D₂O or HOD, abbr. bpV) and picolinamide ligands in solution were explored using multinuclear (¹H, ¹³C, and ⁵¹V) magnetic resonance, COSY, and HSQC in 0.15 mol L^?1 NaCl ionic medium for mimicking physiological conditions. Formation constants among the picolinamide-like ligands are N-(1-hydroxypropan-2-yl)-picolinamide ≈N-(2-hydroxypropyl)-picolinamide>N-(3-hydroxypropyl)-picolinamide>N-propyl-picolinamide. The substituting group influences the equilibrium by electronic effects. The interactions result in a series of new seven-coordinate diperoxovanadate species [OV(O₂)₂L′]^? (L′ = picolinamide-like ligands).     

NMR and theoretical study on interactions between diperoxovanadate complex and 4-substituted pyridines

To understand the substituting group effects of organic ligands on the reaction equilibrium, the interactions between diperoxovanadate complex [OV(O2)2(D2O)]-/[OV(O2)2(HOD)](-) and a series of 4-substituted pyridines in solution were explored using multinuclear (1H, 13C, and 51V) magnetic resonance, DOSY, and variable temperature NMR in 0.15 mol/L NaCl ionic medium for mimicking the physiological condition. Some direct NMR data are given for the first time. The reactivity among the 4-substituted pyridines is pyridine > isonicotinate > N-methyl isonicotinamide > methyl isonicotinate. The competitive coordination results in the formation of a series of new six-coordinated peroxovanadate species [OV(O2)2L](n-) (L = 4-substituted pyridines, n = 1 or 2). The results of density functional calculations provide a reasonable explanation on the relative reactivity of the 4-substituted pyridines. Solvation effects play an important role in these reactions.