Crystal Structure of a CeIII/FeIII Heterobimetallic Complex

A central μ₃—O moiety linking two Fe^III and one Ce^III sites supported by two distinct heterometallic carboxylate bridging modes features in self‐assembled [CeFe₂(bpy)₂(μ₃—O)(μ—L)₂(μ—LH)₂(LH)(H₂O)₂]·0.5(bpy)·7H₂O ( 1 ) (LH₂ = glycolic acid), and the structure models potential bonding modes of the Rare Earth corrosion inhibitor Ce(glycolate)₃ to iron or iron oxide.     

Crystal Structure of a Uranyl/p-tert-Butylcalix[5]arene Complex

The synthesis and crystal structure of the inclusion complex between uranyl and p-tert-butylcalix[5]arene are reported. [UO2 (p-tert-butylcalix[5]arene-4H]2- · &·2MeOH(1) crystallizes in the monoclinic space group C2/c, a = 30.06(2), b = 18.20(3), c = 31.35(2) Å, = 128.51(6)°, V = 13423(40) Å3, Z = 8. Refinement led to a final conventional R value of 0.043 for 4155 reflections. The uranyl ion is bonded, in its equatorial plane, to the five oxygen atoms of the calixarene, four of which are deprotonated. A protonated triethylamine molecule is located inside the calixarene cavity and hydrogen bonded to a uranyl oxygen atom, and another one outside and hydrogen bonded to a calixarene oxygen atom. The calixarene conformation is the usual cone one.     

A Native Ternary Complex Trapped in a Crystal Reveals the Catalytic Mechanism of a Retaining Glycosyltransferase

Glycosyltransferases (GTs) comprise a prominent family of enzymes that play critical roles in a variety of cellular processes, including cell signaling, cell development, and host–pathogen interactions. Glycosyl transfer can proceed with either inversion or retention of the anomeric configuration with respect to the reaction substrates and products. The elucidation of the catalytic mechanism of retaining GTs remains a major challenge. A native ternary complex of a GT in a productive mode for catalysis is reported, that of the retaining glucosyl‐3‐phosphoglycerate synthase GpgS from M. tuberculosis in the presence of the sugar donor UDP‐Glc, the acceptor substrate phosphoglycerate, and the divalent cation cofactor. Through a combination of structural, chemical, enzymatic, molecular dynamics, and quantum‐mechanics/molecular‐mechanics (QM/MM) calculations, the catalytic mechanism was unraveled, thereby providing a strong experimental support for a front–side substrate‐assisted S_Ni‐type reaction.     

Functional Characterization and Crystal Structure of the Type II Peptidyl Carrier Protein ColA1a in Collismycins Biosynthesis†

Collismycins (COLs) are antibiotics characterized by a 2,2′‐bipyridine (2,2′‐BP) core composed of a trisubstituted ring A and an unmodified ring B. The 2,2′‐BP core, which possesses metal‐chelating ability and plays key roles in various biological activities of COLs, is biosynthesized by a nonribosomal peptide synthetase (NRPS)‐polyketide synthase (PKS) hybrid machinery. The starter module of the NRPS‐PKS hybrid machinery consists of a type II peptidyl carrier protein (PCP) ColA1a and an adenylation protein ColA1b. We here report the functional characterization of ColA1a and ColA1b in vitro, confirming their functions in selection and loading of picolinic acid (PA), instead of normal amino acid substrates, as the origin of ring B in COLs. The 2.1 Å crystal structure of ColA1a was solved, revealing structural features including the additional helices α1a, α1b and missing helix α3, which may reflect unique interactions of ColA1a with other NRPS‐PKS proteins/domains or substrate. Primary and tertiary structural comparison of ColA1a with other PCPs revealed the structural basis for their typical α‐helical bundle, providing a better understanding of the structural flexibility of PCPs. These results facilitate the starter module engineering for the generation of COL derivatives with ring B modifications in the future.     

Synthesis and Crystal Structure of a New Salen Complex

Salen Schiff base complexes are some of the most important stereochemical models in transition metal coordina tion chemistry, with their ease of preparation and structural variation. [1] Salen complexes are extensively used as organic reaction catalysts, it was reported to be used in asymmetric cyclopropanation, epoxidation, aziridination, hydrolysis, alkylation, Diels-Alder reaction, reduction, oxidation etc. Here we report the synthesis and structure of a new salen nickel complex 4.     

Crystal Structure and Photoluminescence of a Tetranuclear Cadmium Complex

A novel tetranuclear cadmium complex ([{Cd(C₁₅H₈O₇S)(H₂O)(DMSO)}₃{Cd(C₁₅H₈O₇S)(H₂O)₂}]·3DMSO·H₂O) was obtained by the self‐assembly of Cd(II) with 5,7‐dihydroxyflavone‐6‐sulfonate. The complex was characterized by ¹H NMR, IR, elemental analysis and X‐ray single‐crystal diffraction studies. It crystallizes in triclinic, space group $ P {\bar 1} $ . In the complex, the chelate atoms of Cd(II) are all from oxygen. Four Cd(II) are connected via the carbonyl and 5‐hydroxyanion of four ligands and form an approximate square. Four ligands locate at two sides of the square, and two of them at the same side are almost parallel and exist aromatic π‐π stacking. Ligands on the opposite side of the square are nearly perpendicular. The result of the luminescent studies indicated that the solid of the complex shwed photoluminescent properties because of a combination of coordination, hydrogen bonding and π‐π stacking interaction in the molecule structure. The complex emits green fluorescence (λ_em=496 nm) when it is excited at the wavelength of 440 nm.     

Synthesis and Crystal Structure of a New Sulfur-Palladium-Nitrogen Complex

The reaction of 4-amino-6-methyl-1,2,4-triazine-3(2H)-thione-5-one (AMTTO, 1 ) with palladium(II) chloride in acetonitrile/methanol leads to the N,S-coordinated complex [Pd(η²-AMTTO-N,S)Cl₂] · CH₃OH ( 2 ). 2 has been characterized by IR and MS techniques. The ligand 1 and the complex 2 were also investigated by X-ray structure determinations. 1 crystallizes in the space group P1¯ with the lattice dimensions at –70 °C: a = 419.6(1), b = 598.2(1), c = 1351.3(1) pm, α = 92.23(1), β = 91.20(1), γ = 100.51(1)°, Z = 2, R₁ = 0.0441. 2 crystallizes in the space group P2₁/c with the lattice dimensions at 20 °C: a = 683.3(1), b = 1323.0(1), c = 1254.2(1) pm, β = 92.61(1)°, Z = 4, R₁ = 0.0361. According to the structure analysis 1 consists of planar C,N-heterocycles connected by hydrogen bridges forming an infinite chain along [110]. The basic heterocyclic skeleton of 2 is essentially planar and linked three-dimensionally through hydrogen bridges.     

Synthesis and Crystal Structure of a New Manganese Complex

In order to study the relationship between the manganese ion and the biological coordination agent, the role ofmanganese ion in the active sites and the structure of the active sites in the manganese enzymes, small molecule complexes are often applied to modeling the structure and the properties of reaction in the active centers. In this pa per, we will report the synthesis and crystal structure of a new manganese(Ⅱ) complex, catena[ aqua-(p-methoxybenzoato- O, O′ ) - (p-methoxybenzoato- O )- (2,2′-bipyridine)-manganese (Ⅱ) ] (p-methoxybenzoic acid). The crystal structure was confirmeded by X-ray crystallography analysis.     

新型镍配合物的溶剂热合成及其晶体结构

以2-乙氧基-6-亚氨甲基苯酚(HL)为配体,与氨水和Ni(ClO4)2.6H2O经溶剂热法合成了新型镍配合物[Ni(L)2](1),其结构经IR,元素分析和XRD表征。1属三斜晶系,Pī空间群,晶胞参数a=0.843 3(3)nm,b=1.009 4(2)nm,c=1.188 4(2)nm,α=111.16(3)°,β=97.43(3)°,γ=102.43(3)°,V=0.897 2(11)nm3,Mr=387.05,Z=2,Dc=1 433 g.cm-3,F(000)=404,μ=1.105 mm-1,S=1.015。1中Ni2-分别与两个L-上的两个N原子和两个O原子配位,形成了平面四边形几何构型。分子通过一对N-H┈O氢键形成二聚体;二聚体进一步通过N-H┈O氢键和C-H┈Ni氢键的相互作用形成二维网状结构。     

Hydrothermal Synthesis and Crystal Structure of a Manganese Complex

The title compound [Mn(Phen)(p-MBA)2]n(1) was synthesized via the hydro-thermal reaction of KMnO4 and NaOH with phen and p-methybenzoic acid(p-MBA) in water.The title compound was characterized by elemental analysis and infrared spectra.The crystal of 1 crystallizes in orthorhombic,space group Pbcn with a = 24.132(1),b = 10.404(0),c = 9.386(0) ,V = 2356.65(13) 3,Z = 4,C28H22MnN2O4,Mr = 505.42,Dc = 1.424 g/cm3,F(000) = 1044 and μ(MoKα) = 0.598 mm-1.The final R = 0.0781 and wR = 0.1363 for 1972 observed reflections with Ⅰ 2σ(Ⅰ) and R = 0.0897 and wR = 0.1420 for all data.X-ray diffraction reveals that the Phen and p-methy benzoic acid ligand link the Mn atoms into a single one-dimensional coordination polymer,and extensive intermolecular π-π interactions lead these 1D chains to form a two-dimensional supramolecular architecture.     

Hydrothermal Synthesis and Crystal Structure of a Copper Complex

The title compound [Cu(IB)2]n·n(H2O) 1 was synthesized via the hydrothermal reaction of CuSO4·5H2O and NaOH with 4-(1H-Imidazol-1-yl)benzoic acid(HIB),and character-rized by elemental analysis and infrared spectra.The crystal of 1 crystallizes in monoclinic,space group C2/c with a = 14.349(7),b = 5.977(3),c = 21.368(9) ,β = 104.956(9)o,V = 1770.5(2)3,Z = 4,C20H16CuN4O5,Mr = 455.92,Dc = 1.710 g/cm3,F(000) = 932 and μ(MoKα) = 1.279 mm-1.The final R = 0.0337 and wR = 0.0888 for 1972 observed reflections with Ⅰ 2σ(Ⅰ) and R = 0.0369 and wR = 0.0926 for all data.X-ray diffraction reveals that the IB ligand links the Cu(Ⅱ) atoms into a double stranded chain.The extensive supramolecular interactions lead to the formation of an infinite 2D structure.     

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.     

氰根桥连的锰钴五核配合物的合成与晶体结构

Reaction of [Mn(bpm)₂]²⁺ with K₃[Co(CN)₅(NO)] produces a cyano-bridged bimetallic compound,{[Mn(bpm)₂]_1.5[Co(CN)₅(NO)]}·2H₂O (1), (bpm=bis(1-pyrazol)methane). Compound 1 crystallizes in the tetragonal space group P4₃2₁2 with a=1.305 08(8) nm, b=1.305 08(8) nm, c=4.386 7(5) nm, V=7.471 5(10) nm³, and Z=8. Complex 1 exhibited a structure of a pentanuclear cluster. The Mn²⁺ ions each are surrounded by bpm ligands, forming the [Mn(bpm)₂]²⁺ cation fragment. Three cation fragments are connected to the two anion fragments, [Co(CN)₅(NO)]^3-, by cyanide bridges. The five metal ions form a trigonal bipyramidal structure, where the Mn²⁺ ions are situated in the equatorial plane and the Co²⁺ ions are on both sides of the plane. As a semirigid ligand, bpm is more flexible than rigid 2,2′-bipydine, and it results in the two different configurations in the [Mn(bpm)₂]²⁺ cation fragment. CCDC: 635764.     

Synthesis and Crystal Structure of a New Mononuclear Copper Complex

<正>A new kind of Cu (II) complex [Cu(tpmb)2Cl2]·CH3OH·H2O (tpmb = 1,3,5-tri(2-pyrimidinyl)sulfanylmethyl-2,4,6-trimethylbenzene) was synthesized, and its structure has been determined by X-ray single-crystal diffraction. It crystallizes in the triclinic, space group P 1 with a = 8.8397(2), b = 13.327(3), c = 13.926(3) A, α = 63.27(3), β = 86.96(3), r = 80.68(3)°, V = 1445.6(5) A3, C49H51Cl2CuN12O2S6, Mr= 1166.82,Z=1, F(000) = 604, Dc = 1.340 g/cm3, μ = 0.735 mm-1, R = 0.0545 and wR = 0.1575 for 4521 observed reflections (I > 2σ(I)). X-ray analysis reveals that the Cu (II) ion is coordinated by two Cl- anions and two nitrogen atoms from different pyrimidine groups, forming a square structure.     

Synthesis and Crystal Structure of a Cadmium Complex with Isonicotinate

The cadmium(II) complex, [Cd(iso) 2 (H 2 O) 4 ] (where iso is the anion of isonicotinic acid), has been synthesized and characterized by element analysis, thermal analysis and IR spectroscopy. An X-ray crystal structure reveals that the cadmium ion is trans -octahedral with two pyridyl nitrogens and two aqua oxygens in equational positions and two aqua oxygens in axial positions. The complex forms a three-dimensional network through intermolecular hydrogen bonds.     

Crystal Structure and ESR Study of a Bimetallic Copper/Iron Crown Ether Inclusion Complex

Bimetallic inclusion complexes have been synthesized by a secondary coordination interaction between the guest complex [Fe(η⁵-C₅H₅)(CO)₂(NH₃)][PF₆] and copper(II) complex 1a or nickel(II) complex lb containing crown-ether hosts. The X-ray crystal-structure analysis established that the Cu,Fe inclusion complex 2 crystallize as a centrosymmetric dimer with a Cu? Cu separation of 3.73 Å and a novel out-of-plane Cu? N interaction. The magnetic parameters for 2 were obtained by ESR and ENDOR spectroscopy. ESR susceptibility measurements down to 6 K exclude the presence of any antiferromagnetic coupling interaction between the Cu^IIcenters of the dimer.