The helical melamine–Keggin hybrid nanorods: syntheses and characterizations with two strategies,one-step solid-state chemical reaction and experimental solvent diffusion method

Two new Melamine-Keggin hybrid nanorods, MELH-PMo₁₂ and MELH-PW₁₂, for the first time are successfully synthesized by two chemical methods, one-step solid-state chemical reaction method and experimental solvent diffusion method at room temperature. One-step solid-state reactions involve grounded nanorod materials along with grinding of row material and with solvent diffusion method these nanorods synthesized in single crystals form. These compounds crystallized in trigonal space groups P-3. Elemental analysis, infrared spectroscopy, UV spectroscopy and XRD analysis results prove that the samples still possess Keggin type structure. Transmittance electron microscopy and single-crystal X-ray have shown that the samples have nanorod structures.     

Syntheses,structure and characterization of a fourfold interpenetrated 3D Cd(II) organic framework constructed with a zwitterionic ligand

A 3-D cadmium(II) organic framework with a fourfold interpenetrated diamond topological structure, {[CdLBDC]·(H₂O)₂}_n (1), was synthesized through zwitterionic ligand H₃LBr₃ (1,1′,1″-(2,4,6-trimethylbenzene-1,3,5-triyl)-tris(methylene)tris(4-carboxypyridinium)tribromide), secondary ligand H₂BDC (1,4-benzenedicarboxylic acid) and Cd(NO₃)₂·4H₂O by solvothermal method. Compound 1 was characterized by elemental analyses, FT-IR spectroscopy, powder, and single-crystal X-ray diffraction and thermogravimetric analysis. The photophysical properties of 1 were investigated by solid-state diffuse reflectance spectrum. In 1, each L is linked by two separate Cd(II)-centered distorted tetrahedra, which are also linked by two L, thereby forming a head-to-tail connected 2-D layer structure and further building the 3-D framework through BDC^2?-chelating-bridging between layers.     

Pyridine and benzonitrile adducts of bis(4-nonafluorobiphenyl)zinc

Treatment of (Ar_F′)₂Zn(OEt₂)₂ (Ar_F′ = 4-C₆F₅C₆F₄) with 2 equiv. of benzonitrile, 4-(phenyl)benzonitrile, 4-(pyrrolyl)benzonitrile, pyridine, 4-(phenyl)pyridine or 4-(pyrrolyl)pyridine in dichloromethane afforded the corresponding adducts (Ar_F′)₂ZnL₂ in near quantitative yield. The 2,2′-bipyridine adduct was prepared similarly. Multinuclear NMR spectroscopy indicated that zinc′s four-coordinate character was maintained in solution. The pyridine complex crystallized from dichloromethane with a solid-state structure free of face-to-face aryl–aryl interactions. In contrast, the 4-(pyrrolyl)pyridine adduct crystallized from both dichloromethane and 1,2-difluorobenzene, with solvent of crystallization, but otherwise essentially identical supramolecular architectures assembled through aryl–aryl synthons, including a face-to-face pentafluorophenyl–pyrrole interaction.     

Novel Lanthanide (III) Complexes Derived from an Imidazole–Biphenyl–Carboxylate Ligand: Synthesis,Structure and Luminescence Properties

A series of neutral mononuclear lanthanide complexes [Ln(HL)₂(NO₃)₃] (Ln = La, Ce, Nd, Eu, Gd, Dy, Ho) with rigid bidentate ligand, HL (4′-(1H-imidazol-1-yl)biphenyl-4-carboxylic acid) were synthesized under solvothermal conditions. The coordination compounds have been characterized by infrared spectroscopy, thermogravimetry, powder X-ray diffraction and elemental analysis. According to X-ray diffraction, all the complexes are a series of isostructural compounds crystallized in the P2/n monoclinic space group. Additionally, solid-state luminescence measurements of all complexes show that [Eu(HL)₂(NO₃)₃] complex displays the characteristic emission peaks of Eu(III) ion at 593, 597, 615, and 651 nm.     

Synthesis and crystal structure of two lanthanide coordination compounds of 4-(quinolin-8-yloxy)butanoic acid

Two lanthanide coordination compounds, [La(QYBA)₃H₂O]₂?·?2H₂O (1) and [Eu(QYBA)₃(phen)]₂?·?2H₂O (2), have been synthesized and characterized structurally by X-ray diffraction, where QYBA?=?4-(quinolin-8-yloxy)butanoic acid and phen?=?1,10-phenanthroline. Their solid-state structures have been characterized by elemental analysis and IR spectroscopy. Both form a dimeric molecular structure through bridging oxygen atoms of carboxylate groups and both are nine-coordinate. Adjacent dimers in 1 are interlinked by QYBA into an infinite chain structure, while the dimers in 2 are interlinked by hydrogen bonds and π–π stacking interactions into a two-dimensional network.     

Spectroscopic,thermal and X-ray crystal structure studies of some bis-(pyrazine-2-carboxylato) nickel(II) complexes

Three nickel(II) complexes [Ni(PC)₂(H₂O)₂], 1, [Ni(PC)₂(TU)₂], 2 and [Ni(PC)₂(ABI)₂]· 2(H₂O), 3, PC?=?pyrazine-2-carboxylate, TU?=?thiourea and ABI?=?2-aminobenzimidazole, were synthesized and characterized by elemental analysis, IR spectroscopy and thermal analysis. The complexes were also investigated by single crystal X-ray diffraction analysis. Structures of the monomeric complexes showed nickel(II) chelated to two PC ions from an oxygen atom of carboxylate ion and the adjacent hetero nitrogen atom. The three complexes were crystallized in a monoclinic system with P2 ₁ /c space group for 1, while 2 and 3 had C2/c space groups. The structure of 1 showed two coordinated water molecules occupying the trans positions of a slightly elongated octahedron. The structure of 2 consisted of two PC ions and two thiourea molecules in trans positions. The structure of 3 was different and showed a highly distorted octahedron with two ABI molecules chelated to the nickel ion in cis positions through their hetero nitrogen atoms. Two water molecules of crystallisation were shown in the structure of 3.     

Microstructure elucidation of historic silk (Bombyx mori) by nuclear magnetic resonance

¹H NMR cryoporometry and solid-state ¹³C cross-polarization (CP) magic-angle spinning (MAS) NMR spectroscopy were used to characterize the microstructure of historic and fresh silk samples. Silk is a polymeric bicomponent material composed of fibroin and water located in micropores. According to the ¹H NMR cryoporometry method, the intensity of the water resonance as a function of the temperature was used to obtain the pore size distribution, which was strongly asymmetric with a well-defined maximum at 1.1 nm. Compared with the fresh silk samples, the volume of pores around 1.1 nm decreased distinctly in the historic silk, and more pores larger than 2 nm emerged accordingly. In addition, these results correlated well with solid-state ¹³C CP/MAS NMR spectroscopy as the percentage of random coil in the historic silk sample was much less than that in the fresh silk samples. Therefore, it is suggested that the water-filled microvoids grow larger as the random coil conformation fades away in the degradation process.

Assembly of a new circle connecting circle chain through exerting the template role of a Keggin polyoxometalate

By using the flexible bis(triazole) ligand 1,2-bis(1,2,4-triazol-1-yl)ethane (bte), a polyoxometalate-templated compound, [Zn₂(bte)₄(SiW₁₂O₄₀)]·2H₂O (1), was synthesized under hydrothermal conditions. The compound was characterized by single-crystal X-ray diffraction, elemental analyses, IR spectroscopy, photoluminescence spectroscopy, and cyclic voltammetry. Compound 1 is constructed from two motifs: the [SiW₁₂O₄₀]^4? polyanion and a bi-nuclear metal-organic circle [Zn₂(bte)₂]⁴⁺. The polyanion exerts a template role, inducing the formation of the bi-nuclear circle. The circles build a 1-D circle connecting circle chain through sharing the same Zn ions. Adjacent circles in the chain are vertical with each other. The template polyanion is surrounded by four circles from four different 1-D chains, forming a 3-D supramolecular structure.     

Solvothermal synthesis,characterization and properties of [ReCl<Subscript>5</Subscript>(py)]<Superscript>−</Superscript> complex with T (Néel) of 5.5 K

The synthesis and properties of a rhenium(IV) complex with pyridine as a ligand are presented. The complex, with the formula (2-methyl-pyH)[ReCl₅(py)] 4,4′-bipyridyl 1 has been characterized by elemental analysis, IR spectroscopy, SQUID and X-ray measurements. The single crystal X-ray structure of 1 shows that the rhenium center is of distorted octahedral environment, consisting of five chloride atoms and one pyridine ligand. The solid-state magnetic measurements show antiferromagnetic interactions with T (Néel) of 5.5 K.     

Dynamic study of the noncrystalline phase of 13C-labeled polyethylene by variable-temperature 13C CP/MAS NMR spectroscopy

The ¹³C spin-lattice relaxation times T₁ of ¹³C-labeled polyethylene crystallized under different conditions were measured at temperatures from ?120 to 44°C by variable-temperature solid-state high-resolution ¹³C nuclear magnetic resonance (NMR) spectroscopy, in order to determine accurately the dynamics of the noncrystalline region of the polymer. From these results, it was found that the T₁ minimum for the CH₂ carbons in the noncrystalline region of solution-crystallized polyethylene with high crystallinity appears at higher temperature by about 20°C than that of melt-quenched polyethylene with low crystallinity. This means that the molecular motion of the CH₂ carbons in the noncrystalline regions is more constrained at a given temperature in the material of higher crystallinity. Furthermore, dynamics of the noncrystalline region is discussed in terms of the ¹³C dipolar dephasing times.     

Two diverse temperature-directed cobalt-based coordination polymers: environmentally friendly photocatalysts for degradation of organic dyes

Two new cobalt-based coordination polymers (CPs) based on a semirigid naphthalene-bridged bis-pyridyl-bis-amide ligand, namely [Co(4-bmnpd)(5-HNIP)₂(H₂O)₂] (1) and [Co₄(4-bmnpd)₄(5-NIP)₄]·2H₂O (2) (4-bmnpd?=?N,N′-bis(4-methylenepyridin-4-yl)-2,6-naphthalenedicarboxamide, 5-H₂NIP?=?5-nitroisophthalic acid), have been prepared under hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction analyses, infrared (IR) spectroscopy, and powder X-ray diffraction (PXRD). The structural analyses show that 1 has a one-dimensional (1D) chain structure while 2 exhibits a two-dimensional (2D) network. The effect of temperature on the structures of the CPs is discussed. The solid-state fluorescent properties of 1 and 2 were determined at room temperature. Furthermore, their photocatalytic degradation properties were also studied. Photocatalysts 1 and 2 are environmentally friendly and can effectively degrade organic dye Congo Red (CR) under ultraviolet (UV) light. In addition, the possible degradation mechanism was also investigated.

     

Anion-directed self-assembly of a 2,6-bis(2-anilinoethynyl)pyridine bis(amide) scaffold

Bis(sulfonamide) receptors based on the 2,6-bis(2-anilinoethynyl)pyridine scaffold form persistent dimers with water and halides in solution and in the solid-state. The structurally related bis(amide) receptor derived from 3,5-dinitrobenzoyl chloride is a dimer in the solid-state with two HCl molecules directing the self-assembly. The 2+2 dimer, with a twisted ‘S’-shaped backbone, is held together by six hydrogen bonds. Dissolution of the (H2⁺√Cl ^? )₂ adduct in CHCl₃ results, however, in a monomeric structure. DOSY and ¹H NMR experiments were used to identify the dominance of monomer in solution for both 2 and H2⁺√Cl ^? . The ‘OFF–ON’ fluorescence response of 2,6-bis(2-anilinoethynyl)pyridine is retained with amide arms.     

pH-dependent synthesis of a cadmium coordination compound from a compound based on Hpytz ligand [Hpytz = 5-(4-pyridyl)tetrazole]

Reactions of CdSO₄·6H₂O and Hpytz [Hpytz = 5-(4-pyridyl)tetrazole] under high pH values produced a known compound, [Cd(pytz)₂(H₂O)₄]·2H₂O (1), which can be used to prepare [Cd(Hpytz)(SO₄)(H₂O)₂] (2) by adjusting the pH to a lower level using sulfuric acid under hydrothermal conditions. These compounds were characterized by elemental analysis, IR spectroscopy, and single-crystal diffraction. X-ray analysis reveals that 1 features a mononuclear structure, while 2 affords a 1-D polymeric chain structure. Compound 1 displays a 2-D network, while 2 shows a 3-D network by hydrogen bonding interactions. Furthermore, the luminescent properties were investigated at room temperature in the solid state.     

Structural motifs of Au(I)-Cu(I) N-heterocyclic carbene halide complexes

A series of Au(I)–Cu(I) N-heterocyclic carbene (NHC) halide complexes [AuCu₂(im(CH₂py)₂)₂X]²⁺ where X?=?Cl (1), Br (2), I (3) was prepared by refluxing [AuCu₂(im(CH₂py)₂)₂(NCCH₃)₄]³⁺ with the appropriate halide in acetonitrile. The compounds were characterized by NMR, absorption, and fluorescence spectroscopy. They feature similar solution behavior and solid-state photoemissions. The solid-state structures feature a rhomboidal [AuCu₂X]²⁺ core which is influenced by the type of halide. Compared to other Au(I)–Cu(I) NHC complexes, 1–3 comprise a new structural motif containing a bridging halide. The benzimidazolium analog of 1 was also characterized crystallographically. The structure of [AuCu₂(benzim(CH₂py)₂)₂Cl]²⁺(4) features different coordination modes of the NHC ligands with the carbenic carbon bonded to both gold and copper and the pyridyl groups bonded to the same copper(I) ion.     

Charge-assisted N(+)–H···(−)S hydrogen bonds in the crystal structure of selected diammonium thiophenolates

New salts of thiophenol with three flexible aliphatic diamines H₂N(CH₂)_nNH₂ (n = 2, 4 and 6) have been synthesized and characterized by elemental analyses, IR spectroscopy and X-ray crystallography in order to analyze their supramolecular architecture. Structural analyses indicate that in the crystals, proton transfer has occurred, with the –SH group giving ⁽⁺⁾N–H···S^(?) hydrogen bonding interaction. The structure of compound 1 exhibits a two-dimensional network and compounds 2–3 a three-dimensional supramolecular networks, and each of them is based on hydrogen bonds and CH···π interactions. The transfer of proton from the thiol to the diamines was confirmed by the solid-state FTIR spectra of 1–3.

     

一些二茂铁苯基亚胺化合物的合成与表征

通过回流对应的二茂铁苯胺和芳香醛的混合物的同样路径合成了一系列新颖的二茂铁苯基亚胺化合物(5~12)。当暴露于空气时化合物5~12稳定,不发生任何分解。所有化合物均用¹H、¹³C NMR,MS,IR,UV-Vis和元素分析表征。还报导了化合物N-(3-bromo-2-hydroxylbenzylidene)-4-ferrocenylimine(10)的单晶结构,其结晶属单斜晶系P2₁/c空间群。     

Chemical characteristics of the products of the complexation reaction between copper(II) and a tetra-aza macrocycle in the presence of chloride ions

The reaction of copper(II) perchlorate with the hydrochloride salt of 3,6,9,15-tetra-azabicyclo[9.3.1]penta-deca-1,11,13-triene (L1) in acetonitrile forms two macrocyclic complexes that can be characterized: [L1Cu^IICl][ClO₄] (1) and [L1Cu^IICl]₂[CuCl₄] (2). The structural, electronic, and redox properties of these complexes were studied using spectroscopy (EPR and UV–visible) and electrochemistry. In addition, the solid-state structure of 1 was obtained using X-ray diffraction. The copper(II) is five-coordinate ligated by four N-atoms of the macrocycle and a chloride atom. EPR studies of 1 both in DMF and aqueous solution indicate the presence of a single copper(II) species. In contrast, EPR studies of 2 performed in frozen DMF and in the solid-state reveal the presence of two spectroscopically distinct copper(II) complexes assigned as [L1Cu^IICl]⁺ and [Cu^IICl₄]^2?. Lastly, electrochemical studies demonstrate that both [L1Cu^IICl]⁺ and [Cu^IICl₄]^2? are redox active. Specifically, the [L1Cu^IICl]⁺ undergoes a quasi-reversible Cu(II)/(I) redox reaction in the absence of excess chloride. In the presence of chloride, however, the chemical irreversibility of this couple becomes evident at concentrations of chloride that exceed 50 mM. As a result, the presence of chloride from the chemical equilibrium of this latter species impedes the reversibility of the reduction of [L1Cu^IICl]⁺ to [L1Cu^ICl]⁰.     

A series of tetranuclear [Ln4] clusters with defect-dicubane cores including a Dy4 single-molecule magnet

A series of tetranuclear lanthanide compounds, [Ln₄(μ₃-OH)₂L₄(NO₃)₂(DMF)₂] (H₂L = 2-(2-hydroxy-3-methoxybenzylideneamino)phenol; Ln = Dy (1); Tb (2); Er (3); and Gd (4)), have been prepared under hydrothermal conditions. X-ray crystal structure analysis reveals that 1–4 are polymorphs. The cores of the structures can be described as co-planar defect-dicubane. The solid-state luminescent properties indicate that the Ln^III ions have very deep influence on the luminescence of H₂L. The magnetic properties for 1–4 were studied. The Dy₄ complex exhibits single-molecule magnet behavior.     

缩氨基(硫)脲席夫碱化合物的自发对称性破缺研究

制备了4-苯基-1-(吡啶-2-亚甲基)氨基脲(PPMSC)和4-苯基-1-(吡啶-2-亚甲基)氨基硫脲(PPMTC).用元素分析、MS、1HNMR、UV吸收光谱、X射线单晶衍射和固体CD光谱等对其进行了表征.晶体结构数据显示PPMSC属于Sohncke P212121空间群,单个分子之间通过氢键形成一个一维螺旋链状结构,沿a轴形成左手螺旋结构.固体CD光谱和重结晶实验证明,PPMSC手性晶体的形成是结晶诱导的绝对不对称合成.PPMTC的固体CD光谱和重结晶实验具有与PPMSC类似现象.