双齿膦参与的非均三脚架配位银化合物的合成、结构与表征

近年来,由于在发光材料及一些生物酶的模拟方面有着重要的价值,研究三脚 架有机配体与金属离子自组装形成的配合物引起了人们的极大兴趣。有许多稀土及 银的配合物被报道。从结构的角度来看,非均三脚架配体的三个支架可以有不同类 型的翻转,加上所其带基团的多样性,使其可具有较均三脚架配体更丰富多变的配 位方式,为具有新颖结构的功能材料的设计提供了新思路。     

Solution NMR Structure of a Ligand/Hybrid-2-G-Quadruplex Complex Reveals Rearrangements that Affect Ligand Binding

Telomeric G-quadruplexes have recently emerged as drug targets in cancer research. Herein, we present the first NMR structure of a telomeric DNA G-quadruplex that adopts the biologically relevant hybrid-2 conformation in a ligand-bound state. We solved the complex with a metalorganic gold(III) ligand that stabilizes G-quadruplexes. Analysis of the free and bound structures reveals structural changes in the capping region of the G-quadruplex. The ligand is sandwiched between one terminal G-tetrad and a flanking nucleotide. This complex structure involves a major structural rearrangement compared to the free G-quadruplex structure as observed for other G-quadruplexes in different conformations, invalidating simple docking approaches to ligand–G-quadruplex structure determination.     

Energetic Basis of AGCGA‐Rich DNA Folding into a Tetrahelical Structure

It was recently discovered that, besides well‐known G‐quadruplexes and i‐motifs, DNA may adopt another type of noncanonical structure called AGCGA‐quadruplexes. Here, the folding of the VK2 fragment from the regulatory region of the PLEKHG3 gene is studied and, for the first time, the energetic contributions that stabilize this unique fold are described. Similarly to the B‐DNA, it is stabilized by hydrophobic desolvation and, in contrast to G‐quadruplexes, also by specific binding of water molecules. Compared to B‐DNA, VK2 folding is enthalpically less favorable due to poorer base‐stacking interactions, resulting in substantial conformational flexibility. This entropically favorable conformational “breathing” stabilizes the AGCGA‐quadruplexes. In conclusion, AGCGA‐quadruplexes have a distinguishing thermodynamic fingerprint and the corresponding driving forces enabling their folding are consistent with the observed structural features.     

混配络合物中配位体最佳浓度比的理论研究

我们认为,如金属离子M能与配位体A和B形成二元络合物,那么在配位数允许和不存在空间障碍的情况下,总有三元络合物形成.但由于两种配位体之间的浓度比例调节不当,会造成三元络合物在溶液里的所有组份中占很小的比例,这样,往往给人们一个错觉,即没有三元络合物形成,三元混配络合物在溶液里所有组份中所占的比例达到极大时,两配位体之间的浓度比例是可以通过计算得到的。     

Synthesis and Crystal Structure of a New Complex Constructed from a Flexible Tetrapyridyl Ligand

The title complex [Cd2(NO3)2(OCH3)2(TPOM)2]·8H2O (TPOM=tetrakis(4-pyri- dyloxymethylene) methane) has been synthesized and characterized by IR spectroscopy, elemental analysis and single-crystal X-ray diffraction. It crystallizes in the orthorhombic crystal system Ccca with a=17.125(2), b=40.751(3), c=24.938(2) , β = 90.00o, V= 7403(3) ·3, C26H27N5O8Cd, Mr = 649.93, Z=16, F(000) = 5280, Dc = 0.992 mg/m3, μ(MoKα) =0.538 mm-1, S=1.080, the final R = 0.0533 and wR=0.1449 for 6627 observed reflections (I>2σ(I)). The crystal structure shows that each Cd atom is coordinated to four pyridyl nitrogen atoms from four TPOM ligands and each tetrahedral TPOM ligand links up four Cd atoms into a 2-fold interpenetrating 3D framework. The TG analysis shows that the framework of the title complex is stable up to 300 ℃.     

Crystal Structure of Carboxypeptidase a Complexed with an Inactivator in a New Crystalline Form

1INTR0DUCTIONInrecentyears,zinc-containingmeta1loenzymeshavereceivedspecialattentionbecauseoftheroletheyplayintheetiologyofmanyseriousdiseases.Theyserveastargetsinthedesignoftherapeuticallyusefulinhibitorsoftheseenzymes.Inthisre-spect,carboxypeptidaseA(CPA),awell-studiedzinc-containingmetalloex-opeptidase,bearsanunusualimportancebecauseitservesasamodelformanymetal-loenzymes.Thetertiarystructure0fCPAinc1udingthatoftheactivesitehasbeenwellcharacterizedalth0ughthecataIyticmechanismatthemo…     

一种双肟四核铜(Ⅱ)配合物的合成、结构及热稳定性研究

由螯合双肟配体3,3′-二甲氧基-2,2′-[(1,3-亚丙基)二氧双(氮次甲基)]二酚(H₂L)与四水合苦味酸铜作用,合成了一种新的四核铜(Ⅱ)配合物 [Cu₄L₂(pic)₄(H₂O)₂]·2CH₃COCH₃·2H₂O(pic^-=苦味酸根)。用X-射线单晶衍射仪测定了该配合物的晶体结构：配合物属单斜晶系,P2₁/c空间群,由4个Cu^Ⅱ离子,2个四齿的L2-单元,4个配位的苦味酸根(pic^-),2个配位的水分子,2个结晶的丙酮分子和2个结晶的水分子组成。Cu^Ⅱ离子的配位数为6,都具有稍微扭曲的八面体结构。且配合物分子通过分子间O-H…O氢键作用形成了1个二维超分子结构。     

芳香羧酸铕-含氮杂环配体三元配合物的合成及性质研究

分别以苯甲酸、苯乙酸、β-苯丙酸、苯丙烯酸为第一配体,1,10-邻菲口罗啉或2,2′-联吡啶为第二配体,合成了7种铕(Ⅲ)的三元配合物。通过元素分析、配位滴定分析,确定了各配合物的组成。通过红外光谱对配合物的结构进行了初步表征,在配合物中羧基氧原子和邻菲口罗啉及联吡啶中的氮原子均参与了配位。采用TG-DTG技术对7种配合物的热分解过程进行了研究,以phen为第二配体的4种铕(Ⅲ)的三元配合物具有良好的热稳定性。室温下测定了各配合物粉末的激发和发射光谱。结果表明:羧酸配体相同,以邻菲口罗啉为第二配体的配合物的荧光强度要大于以联吡啶为第二配体的配合物的相应荧光强度。7种铕(Ⅲ)的三元配合物中,最强发射峰强度顺序为:Eu(-βPPA)3phen>Eu(BA)3phen>Eu(PLA)3phen>Eu(BA)3bipy>Eu(PLA)3bipy>Eu(CA)3phen.H2O>Eu(CA)3bipy(其中BA为苯甲酸根、PLA为苯乙酸根、β-PPA为β-苯丙酸根、CA为苯丙烯酸根、phen为1,10-邻菲口罗啉、bipy为2,2′-联吡啶)。     

基于配合物配体策略的Cu-Cd异核配位聚合物的合成与晶体结构

利用小分子配合物[Cu(2-mpac)₂(H₂O)]•3H₂O (1)作为配合物配体, 以其两侧未配位的羰基氧原子与金属配位合成了一个Cu-Cd异核配位聚合物[Cu(2-mpac)₂(H₂O)₂Cd(H₂O)₄(NO₃)₂]_n (2) (2-mpac＝5-methyl-2-pyrazinecarboxylic acid), 并利用元素分析、红外光谱以及X射线单晶衍射法对标题化合物进行了表征. 晶体学数据: 三斜晶系, P-1空间群, a＝0.7654(7) nm, b＝0.8903(8) nm, c＝0.9745(9) nm, α＝116.116(1)°, β＝98.408(1)°, γ＝90.335(1)°, V＝0.5880(9) nm³, Z＝1, S＝1.053, 最终残差因子[I＞2σ(I)] R₁＝0.0280, wR₂＝0.0718, 对于全部数据R₁＝0.0305, wR₂＝0.0741.     

Synthesis and Crystal Structure of a Zeolite-like Metal-organic Framework Based on the Triazole Ligand

A novel zeolite-like metal-organic framework, [Cd12（trz）12＇F10＇（SiF6）3]·（H3O）4 （Htrz = 1,2,4-triazole）, has been synthesized under solvothermal conditions using 1H-l,2,4-triazole-3- carboxylic acid and CdF2 as the starting materials. The complex has been characterized by elemental analysis, IR, SEM-EDS, gas adsorption, powder and single-crystal X-ray diffraction analyses. The title complex crystallizes in the cubic 1-43m space group, with a = 14.6436（8）, V= 3140.1（3）A3, Z = 2, Mr = 2857.96, D,.= 3.023 g/cm3 and F（000） = 2668. The final R = 0.0653 and wR = 0.1880 for 586 observed reflections with 1 〉 2σ（I）. In the title complex, three adjacent Cd（ll） centers are connected by three p3-bridging triazole ligands to form triagonal secondary building units （SBUs）, which are further interconnected to form a three-dimensional skeleton with tetrahedral cages.     

基于草酰胺配体的新型异双核配合物的合成及其晶体结构

以草酰胺铜配合物CuL(H₂L=2,3-二氧-5,6 :13,14-二联苯基-9,10-环己基-1,4,8,11-四氮杂十四环-7,12-二烯烃)为前驱配体,1,10-邻菲啰啉为端接配体,高氯酸锰为金属核心,经回流反应合成了一个新型的异双核配合物［CuLMn(phen)₂］(ClO₄)₂·2CH₃OH(1),其结构和性能经UV-Vis, IR,元素分析,X-射线粉末衍射和X 射线单晶衍射表征。结果表明：1(CCDC: 1 445 582)属三斜晶系,空间群P-1,晶胞参数a=11.298(19) , b=15.17(4) , c=16.71(3) ,α=113.69(3), β=109.30(2), γ=93.08(4), V=2 417(9) ³, Z=2。 1在DMF中的最大吸收峰位于272 nm和361 nm。     

G-rich VEGF aptamer as a potential inhibitor of chitin trafficking signal in emerging opportunistic yeast infection

The alarm is rang for friendly fire; Saccharomyces cerevisiae (S. cerevisiae) newfound as a fungal pathogen with an individual feature. S. cerevisiae has food safety and is not capable of producing infection but, when the host defenses are weakened, there is room for opportunistic S. cerevisiae strains to cause a health issues. Fungal diseases are challenging to treat because, unlike bacteria, the fungal are eukaryotes. Antibiotics only target prokaryotic cells, whereas compounds that kill fungi also harm the mammalian host. Small differences between mammalian and fungal cells regarding genes and proteins sequence and function make finding a drug target more challenging. Recently, Chitin synthase has been considered as a promising target for antifungal drug development as it is absent in mammals. In S. cerevisiae, CHS3, a class IV chitin synthase, produces 90% of the chitin and essential for cell growth. CHS3 from the trans-Golgi network to the plasma membrane requires assembly of the exomer complex (including proteins cargo such as CHS5, CHS6, Bach1, and Arf1). In this work, we performed SELEX (Systematic Evolution of Ligands by EXponential enrichment) as high throughput virtual screening of the RCSB data bank to find an aptamer as potential inhibit of the class IV chitin synthase of S. cerevisiae. Among all the candidates, G-rich VEGF (GVEGF) aptamer (PDB code: 2M53) containing locked sugar parts was observed as potential inhibitor of the assembly of CHS5–CHS6 exomer complex a subsequently block the chitin biosynthesis pathway as an effective anti-fungal. It was suggested from the simulation that an assembly of exomer core should begin CHS5–CHS6, not from CHS5-Bach1. It is notable that secondary structures of CHS6 and Bach1 was observed very similar, but they have only 25% identity at the amino acid sequence that exhibited different features in exomer assembly.     

含吡嗪甲酸配体的双核铬配合物的水热合成、晶体结构及荧光性质

通过水热法合成了1个双核铬配合物[Cr2(OH)2(2-pca)4].3H2O(2-Hpca=2-吡嗪甲酸),并对其进行了X-射线单晶衍射、红外光谱、元素分析、荧光和热的表征及研究。该配合物属于单斜晶系,P21/c空间群。晶体学数据:a=1.566 35(15),b=0.847 70(6),c=1.974 60(18)nm,β=90.645 0(10)°,C20H20Cr2N8O13,Mr=684.44,V=2.621 7(4)nm3,Dc=1.734 g.cm-3,F(000)=1 392,μ=0.913 cm-1,Z=4,最终R=0.044 7,wR=0.112 0用于3 251个可观测点。在晶体结构中,每个铬原子均为六配位,其中来自两分子2-吡嗪甲酸的2个氮原子、2个羧酸基氧原子和2个桥连羟基上的氧原子,呈现畸变的八面体几何构型。     

配体分子结构对Pd(Ⅱ)-Phen-PCA体系堆积作用的影响

用pH电位滴定法测定了含l，10-邻菲咯啉(Phen)和羧酸(CA)配体的三元混配配合物Pd(Phen)(CA)体系的稳定常数，比较和讨论了各种三元混配配合物之间的稳定性差异．实验结果表明，在三元混配配合物Pd(Phen)(PCA)中(PCA为苯基羧酸)存在分子内芳环堆积作用，堆积程度依赖于苯基和配位的羧酸根之间的亚甲基数目，其中以2-苯乙酸和3-苯丙酸与邻菲咯啉为最佳堆积．     

Synthesis,Crystal Structure,and Magnetic Properties of a New Dinuclear Iron Complex with Schiff Base Ligand

A new dinuclear iron(Ⅲ) complex has been synthesized and structurally characterized by X-ray crystallography: [FeⅢ2(L)(C6H5COO)(SO4)(CH3OH)2]·CH3CN·CH3OH(1, H3 L = N,N'-bis(salicylidene)-1,3-diamino-2-propanol). Complex 1 belongs to orthorhombic space group Pna21 with a = 11.4400(8), b = 22.9705(2), c = 12.5712(9) , V = 3303.5(4) 3, Z = 4, F(000) = 1576, Dc = 1.531 g·cm–3, Mr = 761.36, μ = 1.007 mm–1, S = 1.014, the final R = 0.0505 and wR = 0.1018. The crystal packing is stabilized by intermolecular O–H···O hydrogen bonds, forming an extended one-dimensional chain structure. The temperature dependence of magnetic susceptibility measurement shows that antiferromagnetic interaction is propagated between the metal centers. Fit as dinuclear arrangement gave parameters of J = 19.7 cm-1, g = 1.89 and R2 = 0.9999.     

Synthesis, Crystal Structure and Photoluminescent Property of a Novel Disilver Complex with Pyrazinyl Oxime Ligand

<正>A novel binuclear Ag(I) complex [Ag_2(C_6H_6N_3O)_2(C_6H_7N_3O)_2]·2CH_3CN (1) was synthesized by the evaporation reaction of silver nitrate and (E)-1-(pyrazin-2-yl)ethanone oxime (HL). The complex was characterized by elemental analysis, IR spectrum and X-ray single-crystal diffraction analysis. It crystallizes in the monoclinic space group C2/c with a = 22.7089(3), b = 11.5443(7), c = 16.1468(4) , β = 127.7150(10)°, V = 3348.6(2) ~3, D_c = 1.675 g/cm~3, M_r = 844.42, Z = 4, F(000) = 1696.0, μ = 1.226 mm~(-1), the final R =0.0250 and wR = 0.070. The coordination around the silver(I) atom is a distorted trigonal-bipyramidal geometry involving one protonated pyrazinyl oxime ligand (HL), one deprotonated oxime ligand (L~-) and one CH_3CN solvate molecule in the asymmetric unit of complex 1.     

Synthesis and Crystal Structure of a Novel Tetranuclear Manganese(II) Complex with a Tripodal Peptide Ligand

1 INTRODUCTION Amides play an important role in the evolution ofnature. The amidate participates in the coordinationof iron with the ligands containing biomolecules, suchas antitumor drug bleomycin[1] and nitrile hydra-tase[2]. Bleomycin is a clinically useful antitumoragent which catalyzes the cleavage of oxidative DNAand oxidizes a number of organic substrates with di-oxygen or H2O2 . This has raised more interest in [3]the coordination of amide complexes[4, . …     

Inducement and stabilization of G-quadruplex DNA by a thiophene-containing dinuclear ruthenium(II) complex

G-quadruplex structures are attractive targets for the development of anticancer drugs, as their formation in human telomere could impair telomerase activity, thus inducing apoptosis in cancer cells. In this work, a thiophene-containing dinuclear ruthenium(II) complex, [Ru₂(bpy)₄(H₂bipt)]⁴⁺ {bpy = 2,2′-bipyridine, H₂bipt = 2,5-bis[1,10]phenanthrolin[4,5-f]-(imidazol-2-yl)thiophene}, was prepared and the interaction between the complex and human telomeric DNA oligomers 5′-G₃(T₂AG₃)₃-3′ (HTG21) has been investigated by UV-Vis, fluorescence and circular dichroism (CD) spectroscopy, fluorescence resonance energy transfer (FRET) melting assay, polymerase chain reaction (PCR) stop assay, fluorescent intercalator displacement (FID) titrations, Job plot and color reaction studies. The results indicate that the complex can well induce and stabilize the formation of antiparallel G-quadruplex of telomeric DNA in the presence or absence of metal cations, and the ΔT_m value of the G-quadruplex DNA treated with the complex was obtained to be 12.8 °C even at levels of 50-fold molar of duplex DNA (calf-thymus DNA), suggesting that the complex exhibits higher G-quadruplex DNA selectivity over duplex DNA. The complex shows high interaction ability with G-quadruplex DNA at (1.17 ± 0.12) × 10⁷ M^?1 binding affinity using a 2:1 [complex]/[quadruplex] binding mode ratio. A novel visual method has been developed here for making a distinction between G-quadruplex DNA and duplex DNA by our ruthenium complex binding hemin to form the hemin-G-quadruplex DNAzyme.     

新型二维网状双席夫碱银配合物的合成与结构

席夫碱配体由于在合成上具有极大的灵活性和良好的配位能力 ,因而席夫碱 -金属配合物的研究一直受到广泛重视 .多年来 ,席夫碱配体由简单的单齿发展到多齿和大环配体 .此外 ,过渡金属的席夫碱配合物具有独特的结构、性能和广泛的应用 ,如氧化还原 [1] 、催化 [2 ] 以及生物体系的化学模拟 [3 ] ;另一方面 ,由于银原子配位方式的多样性 (二、三、四和五配位 ) ,便于人们对超分子化合物的组装规律进行系统研究 ,因而银配合物的研究正日益引起人们极大的兴趣 [4～ 7] .鉴于此 ,我们设计合成了一个新的四齿席夫碱配体 L ,研究了其与 CF3 SO3 …