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71.
铜是重要的生命元素,它与铁一样能起到输送氧气和电子载体的作用。把铜的配合物作为生物体内金属离子/酶/底物间相互作用的模拟研究一直十分活跃犤1~4犦。我们选取Cu?与吡啶-2,6-二甲酸(H2DPC)和8-羟基喹啉(HOx),合成了配合物犤Cu(HDPC)2犦·(HOx)2·6H2O,并获得其单晶,测定了其晶体结构,讨论了存在于体系中的氢键作用。1实验部分1.1配合物的合成先将1mmolH2DPC用NaOH(1mmol·L-1)溶液调配成pH=7.0的钠盐,然后滴加10mL溶有1mmolHOx的95%乙醇溶液,在搅拌下,上述混合液慢…  相似文献   
72.
The odd–even effect in luminescent [Eu2(L)3(H2O)x]⋅y(H2O) complexes with aliphatic dicarboxylate ligands (L: OXA, MAL, SUC, GLU, ADP, PIM, SUB, AZL, SEB, UND, and DOD, where x=2–6 and y=0–4), prepared by the precipitation method, was observed for the first time in lanthanide compounds. The final dehydration temperatures of the Eu3+ complexes show a zigzag pattern as a function of the carbon chain length of the dicarboxylate ligands, leading to the so-called odd-even effect. The FTIR data confirm the ligand–metal coordination via the mixed mode of bridge–chelate coordination, except for the Eu3+-oxalate complex. XRD results indicate that the highly crystalline materials belong to the monoclinic system. The odd–even effect on the 4 f–4 f luminescence intensity parameters (Ω2 and Ω4) is explained by using an extension of the dynamic coupling mechanism, herein named the ghost-atom model. In this method, the long-range polarizabilities ( ) were simulated by a ghost atom located at the middle of each ligand chain. The values of were estimated using the localized molecular orbital approach. The emission intrinsic quantum yield ( ) of the Eu3+ complexes also presented an the odd-even effect, successfully explained in terms of the zigzag behavior shown by the Ω2 and Ω4 intensity parameters. Luminescence quenching due to water molecules in the first coordination sphere is also discussed and rationalized.  相似文献   
73.
《Mendeleev Communications》2022,32(2):170-172
A selectivity-switched dimerization process for (5-phenyl-2-thienyl)cyclopropane-1,1-dicarboxylate under activation conditions with anhydrous Gaiii salts was developed. Using GaCl3 or Ga(NTf2)3 as catalysts, 3a,4,5a,6,7,8-hexahydro-5H-pentaleno[6a,1-b]thiophene and 5,6-dihydro-4H-cyclo-penta[b]thiophene derivatives can be selectively obtained as a result of ipso-type and [3+2]-annulation type dimerization. The crucial role of a phenyl substituent at position 5 of the thiophene ring and some regularities are discussed.  相似文献   
74.
The internal functionalization of the Keplerate‐type capsule Mo132 has been carried out by ligand exchange leading to the formation of glutarate and succinate containing species isolated as ammonium or dimethylammonium salts. Solution NMR analysis is consistent with asymmetric inner dicarboxylate ions containing one carboxylato group grafted onto the inner side of the spheroidal inorganic shell while the second hangs toward the center of the cavity. Such a disposition has been confirmed by the single‐crystal X‐ray diffraction analysis of the glutarate containing {Mo132} species. A detailed NMR solution study of the ligand‐exchange process allowed determining the binding constant KL of acetate (AcO?), succinate (HSucc?) or glutarate (HGlu?) ligands at the 30 inner coordinating sites, which vary such as K<K<Ksupported by the associated thermodynamic parameters ΔrS* and ΔrH*. Such a variation is mainly explained by a positive entropic gain attenuated by unfavorable steric effect. Furthermore, these results are completed by 1H DOSY and 1H EXSY NMR experiments which are in agreement with bulky guests firmly trapped within the cavity. At last, variable temperature 1H NMR study below 290 K revealed a striking line broadening occurring abruptly within a 5 K range. Such an effect appears closely related to the presence of the ammonium cations suspected to be present within the cavity and then has been interpreted as an inner‐phase transition leading to a frozen state.  相似文献   
75.
研究了5种新型内给电子体对Ziegler-Natta催化剂结构和催化性能的影响.结果表明,使用两种不同制备工艺制备的氯化镁载体均为δ晶型,而不同的内给电子体的加入使得催化剂的氯化镁载体具有不同的微晶结构和形态.在催化剂制备阶段中,内给电子体的加入方式对催化剂的性能有很大的影响.在5种内给电子体中,以cis-1,2-环己二甲酸二异丁酯为内给电子体时,催化剂的聚合活性和PP等规度最高,性能与工业催化剂相当;当选用cis-1,2-环己二甲酸二异丁酯为内给电子体,CMMS为外给电子体,硅钛物质的量之比为10及铝钛物质的量之比为100时,催化剂的聚合活性和PP等规度达到最高.  相似文献   
76.
三环己基氢氧化锡分别与辛二酸和壬二酸进行甲醇溶剂热反应,合成了2个双(三环已基锡)二元酸酯(CH2)n(CO2SnCy3)2[(n:6(1),7(2)],并用IR、1H和13C NMR、元素分析和X射线单晶衍射表征结构。化合物12均属单斜晶系,空间群分别为P21/nP21/c,在化合物的晶体中,1通过Sn-O共价键,2通过Sn-O和Sn…O弱作用,分别形成了四锡核30元(1)和32元(2)二维大环网状结构。化合物12对人癌细胞Colo205、HepG2、MCF-7、Hela、NCI-H460均具有良好的体外抑制活性,对S. AureusB. SubtilisE. ColiS. Typhi具有选择性的抑菌作用。  相似文献   
77.
本文首先合成了多功能有机桥联配体:2-(对溴)苯基-4,5-咪唑二羧酸(p-BrPhH3IDC),使之与Ni(Ⅱ)在溶剂热条件下自组装,得到了一个二维配位聚合物{[Ni(p-BrPhH2IDC)2]·2H2O}n (1)。采用红外光谱、元素分析以及X-ray单晶衍射表征了这个配合物的分子结构。结果表明:H3BrPhIDC配体表现出比较强的配位能力,这和通过量子化学计算给出的预测一致。研究了此配聚物在空气气氛下的热稳定性以及采用变温磁化率研究了在2.0~300 K范围内的磁性质。结果表明:在配合物1中,相邻镍离子间存在着弱的反铁磁偶合作用。  相似文献   
78.
A series of new metal-organic frameworks (MOFs) based on 9,10-bis(imidazol-1-ylmethyl)anthracene and four structurally related aromatic dicarboxylates, namely, [Cd(L)(o-bdc)]·1.25H2O (1), [Cd(L)(pydc)] (2), [Zn(L)(pydc)] (3), [Cd3(L)2(m-bdc)3] (4) and [Cd(L)(p-bdc)]·2H2O (5) (L = 9,10-bis(imidazol-1-ylmethyl)anthracene, o-H2bdc = 1,2-benzenedicarboxylic acid, H2pydc = 2,3-pyridinedicarboxylic acid, m-H2bdc = 1,3-benzenedicarboxylic acid, p-H2bdc = 1,4-benzenedicarboxylic acid) have been synthesized under hydrothermal conditions. Their structures have been determined by single-crystal X-ray diffraction analyses, and further characterized by infrared spectra (IR), elemental analyses and powder X-ray diffraction (PXRD). Compound 1 displays a two-dimensional (2D) layer structure, which is stabilized by intramolecular hydrogen-bonding interactions. Compounds 2 and 3 are isostructural and show 2D layer structures, which are further extended by intermolecular C-H···O hydrogen-bonding interactions to form 3D supramolecular frameworks. Compound 4 has a 2D layer structure with trinuclear units [Cd3(u3-O)2]6+. Compound 5 is a 3D three-fold interpenetrating framework with a Schläfli symbol (66·8). The structural differences of these compounds indicate that the anions play important roles in the resulting structures of the MOFs. The luminescent properties were also investigated for compounds 1-5.  相似文献   
79.
The hydrothermal reactions of Cd, Zn, or Cu(II) acetate salts with H2PHDA and BPP flexible ligands afford three new coordination polymers, including [Cd(PHDA)(BPP)(H2O)]n(1), [Zn(PHDA)(BPP)]n(2), and [Cu2(PHDA)2(BPP)]n(3) (H2PHDA=1,2-phenylenediacetic acid, BPP=1,3-bis(4-pyridyl)propane). The single-crystal X-ray diffractions reveal that all three complexes feature various metal carboxylate subunits extended further by the BPP ligands to form a diverse range of structures, displaying a remarked structural sensitivity to metal(II) cation. Complex 1 containing PHDA-bridged binuclear cadmium generates 1D double-stranded chain, complex 2 results in 2D→2D interpenetrated (4,4) grids, and complex 3 displays a 3D self-penetrated framework with 48668 rob topology. In addition, fluorescent analyses show that both 1 and 2 exhibit intense blue-violet photoluminescence in the solid state.  相似文献   
80.
The three‐dimensional ZnII coordination polymer poly[[bis(μ2‐benzene‐1,4‐dicarboxylato){μ4N1,N3,N5‐tris[(pyridin‐3‐yl)methyl]benzene‐1,3,5‐tricarboxamide}dizinc(II)] monohydrate], {[Zn2(C8H4O4)2(C27H24N6O3)]·H2O}n, is characterized by a rare (4,4,4)‐connected (4.62.72.8)(4.62.73)(42.62.72) topology. The tricarboxamide ligand adopts an unprecedented tetradentate coordination mode, with one carboxamide O atom participating in the coordination. The polymer was further characterized by thermogravimetric and solid‐state luminescence analysis.  相似文献   
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