Na Xing

Neutral mononuclear, dinuclear, tetranuclear d7/d10 metal complexes containing bis-pyrazole/pyridine ligands supported by 2,6-bis(3-pyrazolyl)pyridine: synthesis, structure, spectra, and catalytic activity.

A series of novel bis-pyrazole/pyridine complexes, [Zn(2)(HL(1))(2)(μ(2)-SO(4))](2)·EtOH·H(2)O (1), [Co(2)(HL(1))(2)(μ(2)-SO(4))](2)·2DMF·6H(2)O (2), [Zn(4)(HL(1))(4)(μ(4)-SO(4))][OH](2) (3), [Zn(2)(HL(2))(2)(μ(2)-SO(4))]·2H(2)O (4), [Zn(H(2)L(2))(H(2)O)(2)](SO(4))·0.87H(2)O (5) (H(2)L(1) = 2,6-di-(5-phenyl-1H-pyrazol-3-yl)pyridine, H(2)L(2) = 2,6-di-(5-methyl-1H-pyrazol-3-yl)pyridine), were synthesized hydrothermally from the self-assembly of Zn(II) or Co(II) with different types of bipyrazolyl/pyridine derivative ligands. All the complexes were characterized by elemental analysis, IR and UV-vis spectroscopy, powder X-ray diffraction (PXRD), and single-crystal X-ray diffraction. Structural analyses revealed that metal atoms (Zn and Co) in complexes 1-5 are five-coordination modes, forming slightly distorted trigonal bipyramidal geometries. In complexes 1-3, H(2)L(1) ligand connected the two metal centers via the tetradentate fashion, and the same form of connection was found in complex 4 with H(2)L(2) ligand. While in complex 5, H(2)L(2) only connected with one metal center via the tridentate fashion, which was different from those in complexes 1-4. Additionally, there are abundant hydrogen bonding interactions in complexes 1-4. Interestingly, for hydrogen bonding connecting fashions being different, the molecules for the complexes 1 and 4 are held together by the hydrogen bond to form a 1D supramolecular structure, whereas complexes 2 and 3 are a hydrogen bonded dimer. In addition, quantum chemical calculations for 1, 3, and 4, thermal behaviors and photoluminescent properties for 1 and 3-5 were performed and discussed in detail. In the mean time, we found that these complexes had potential catalytic activity for the oxidation reaction of cyclohexane.

Multi-functional d10 metal–organic materials based on bis-pyrazole/pyridine ligands supported by a 2,6-di(3-pyrazolyl)pyridine with different spanning flexible dicarboxylate ligands: synthesis, structure, photoluminescent and catalytic properties

A series of the novel zinc complexes, Zn3(H2L1)2(ox)3(H2O)2·4H2O (1), Zn(H2L1)(ad)·2H2O (2), Zn2(HL2)2(suc)0.5·(HCOO)·H2O (3), Zn2(HL2)2(glu)·2H2O (4), Zn2(HL2)2 (ad)0.5·(OH)·0.5H2O (5), Zn2(HL2)2(seb)(H2O)·2.5H2O (6), (H2L1 = 2,6-di(5-methyl-1H-pyrazol-3-yl)pyridine, H2L2 = 2,6-di(5-phenyl-1H-pyrazol-3-yl)pyridine, H2ox = oxalic acid, H2ad = adipic acid, H2suc = succinic acid, H2glu = glutaric acid, H2seb = suberic acid) were synthesized hydrothermally from the self-assembly of a Zn(II) ion with different types of the new bi-pyrazolyl pyridine derivative ligands and different spanning flexible dicarboxylic compounds as an auxiliary ligand. They were characterized by elemental analysis, IR and UV–vis spectroscopy, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. We found that they are all molecular compounds using the above detections. The structural analysis indicates that the zinc atom in complex 1 is a six-coordinate mode of ZnO3N3, forming a slightly distorted octahedral geometry, while zinc atoms in complexes 2–6 are all penta-coordination modes of ZnO2N3 and ZnON4 in a distorted bipyramidal geometry. The H2L1 ligand is in the form of a μ1–η1–η1–η1 coordination with metallic Zn in 1 and 2; while the HL2 ligand is in a μ2–η1–η1–η1–η1 coordination mode in 3–6. For the oxalate ligand, there are two kinds of coordination modes, μ2–η1–η1–η1–η1 bridging coordination mode and μ1–η1–η1 terminal coordination mode; the coordination mode of glutaric acid ligand is in the form of μ2–η1–η1; suc2− ligand is in the form of a μ4-bridging coordination fashion with each side carboxylate group in a μ2–η1–η1-monodentate mode; the coordination of the adipic acid ligand presents two coordination modes of μ2–η1–η1and μ4–η2–η2; suberic acid ligand acts in a monodentate terminal coordination mode. In addition, thermal behaviors and photoluminescent properties for 1–6 were all performed and are discussed in detail. The catalytic activity of the complexes is evaluated firstly by the reaction of hydrogen peroxide promoted oxidation of cyclohexane and cyclopentane under mild conditions. It is found that the Zn complexes with five different spanning flexible dicarboxylic acids as an auxiliary ligand with oxalic acid, succinic acid, glutaric acid, adipate acid or sebacic acid, respectively, have potential catalytic activity in the oxidation reaction of cyclohexane.

Synthesis, structure, and catalytic bromination of supramolecular oxovanadium complexes containing oxalate

Three supramolecular complexes, [VO(phen)(C2O4)(H2O)]·CH3OH (1) [(VO)2(u2-C2O4)(C2O4)2(H2O)2]·L·H2O (2), and [(4,4′-bipyH2)0.5]+[VO2(2,6-dipic)]−·2H2O (3) (phen = 1,10-phenanthroline 4,4′-bipy = 4,4′-bipyridine, 2,6-dipic = 2,6-pyridinedicarboxylic, L = 1,4-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)benzene), have been prepared and characterized by elemental analysis, IR, and UV–vis spectroscopy and single-crystal diffraction analysis. Structural analysis shows that the three complexes all contain carboxylate and V=O moiety; vanadium of 1 and 2 are six coordinate with distorted octahedral geometry with N2O4 and O6 donor sets, respectively, while 3 is five coordinate with distorted trigonal bipyramidal geometry with a NO4 donor set. The complexes exhibit catalytic bromination activity in the single-pot reaction for the conversion of phenol red to bromophenol blue in H2O–DMF at 30 ± 0.5 C with pH 5.8, indicating that they can be considered as functional model vanadium-dependent haloperoxidases. In addition, electrochemical behaviors are also studied.

Application in the cyclohexane oxidation of a scorpionate oxovanadium(IV) complex: synthesis, structure, and properties of VO(C5H7O2)(BC9H7N6I3)

An oxovanadium(IV) complex, VO(C5H7O2)(BC9H7N6I3), derived from hydrotris(4-iodinpyrazolyl)borate was designed and synthesized at room temperature in methanol. The complex was characterized by elemental analysis, IR spectra, UV-Vis spectroscopy, and single-crystal X-ray diffraction. The structural analysis shows that the vanadium(IV) center possesses a distorted-octahedral geometry with a N3O3 core, containing a tridentate hydrotris(4-iodinpyrazolyl)borate with nitrogen as three donors. The complex is the first structurally characterized example of a vanadium(IV) complex with hydrotris(4-iodinpyrazolyl)borate. It was used as a catalyst for cyclohexane oxidation under mild conditions and the effects of a variety of factors such as amount of acid and H2O2, the kind of solvent, as well as temperatures were evaluated; the maximum turnover number value reaches 321.

Peroxo- and oxovanadium(iv) complexes with tridentate N-heterocycle ligands: synthesis, structure, and catalytic performance

Three peroxo- and oxovanadium(IV) complexes: [VO(O2)(bpz*eaT)·VO(C4H4O6)]·H2O (1), [VOSO4(bpz*eaT)]·C6H8O7 (2) (bpz*eaT = 2,4-bis(3,5-dimethyl-1H-pyrazol-1-yl)-6-diethylamino-1,3,5-triazine) and [VO(C12H8N2)(C9H7NO3)]·CH3OH·0.5H2O (3) were synthesized and characterized by elemental analysis, IR spectra, UV-Vis spectroscopy and single-crystal X-ray diffraction. In addition, the catalytic performances of complexes 1–3 and their starting materials (VO(acac)2 and VOSO4) were studied by the reaction of cyclohexane (Cy) oxidation. It is found that complex 1 exhibited the highest catalytic activity (TON(cyclohexanol) = 220, TON(cyclohexanone) = 346, Conv. = 97.9%) with H2O2 as an oxidant and HNO3 as an additive at 24 h, 40 °C, indicating that it is a potential candidate catalyst to oxidize the Cy to cyclohexanol (CyOH) and cyclohexanone (CyO) under mild conditions.

CCDC 904699: Experimental Crystal Structure Determination

Related Article: Zhaoyan Deng, Fengying Bai, Yongheng Xing, Na Xing, Liting Xu|2013|Open Journal of Inorganic Chemistry|3|76|doi:10.4236/ojic.2013.34011

A new metallate phase of V2O5 crystalline microstructure achieved in a facile route: synthesis, characterization, and measurement in catalytic reactions.

Experiencing a series of complicated changes, abundant orange crystals of novel metallic phase of vanadium pentoxide were obtained by a mild chemical method, the formula of which is defined as [V3(μ3-O)2⋅(μ1-OH)⋅O5]⋅H2O. Differ from the synthesis methods of vanadium oxide published, we have adopted a simple solution method that mixed starting materials are refluxing in the system of ethanol-water under a relatively lower temperature. Symmetry of the crystals is Monoclinic, with cell unit dimensions: a=4.9978(10)Å, b=8.4273(17)Å, c=7.8669(16)Å, β=96.44(3)° and space group of P2₁/m. The structure of the complex was characterized by elemental analysis, IR, UV-vis spectroscopy and single-crystal diffraction analysis. Powder X-ray diffraction (PXRD) was used to detect the purity of the crystals, and crystal morphology was detected by the scanning electron microscope (SEM). In addition, in order to extend application of oxidovanadium complexes, bromination catalytic activity about the complex in a single-pot reaction of the conversion of phenol red to bromophenol blue in a mixed solution of H2O-DMF at a constant temperature of 30±0.5 °C with a buffer solution of NaH2PO4Na2HPO4 (pH=5.8) was evaluated firstly, indicating that the complex can be considered as a potential functional model of bromoperoxidase, in the meantime, we have conducted the bromination catalytic reaction to simulate and measure the changes in reaction process indirectly. Besides, catalytic oxidation activity of the complex is also evaluated in the oxidation of cyclohexane (Cy) and cyclopentane with hydrogen peroxide promoted under mild conditions, showing potential catalytic activity of the complex by comparing TON (total turnover number) ratios of CyO/CyOH (CyO is the abbreviation of cyclohexanone and CyOH represents cyclohexanol) in the oxidation results.

Investigation into experimental conditions and factors for cyclohexane oxidation with VO(acac)2

The catalytic activity of VO(acac)2 for the cyclohexane(Cy) oxidation was studied. The effects of various parameters, such as the amounts of H2O2, HNO3, H2O and Cy were investigated. The highest total turnover number(TON) is 234, which can be increased to 353, 342 and 403, respectively with the adding of o-phthalic, m-phthalic or p-phthalic acid. A reaction mechanism was also supposed primarily.

CCDC 854265: Experimental Crystal Structure Determination

Related Article: Xiaoxi Zhang, Na Xing, Fengying Bai, Lijuan Wan, Hui Shan, Yanan Hou, Yongheng Xing, Zhan Shi|2013|CrystEngComm|15|9135|doi:10.1039/C3CE41213J

Crystal engineering of multiple-component organic compound: Organic co-crystals of the functional groups of carboxyl and amino with persistent hydrogen bonding motifs

Three small organic molecular co-crystal compounds (C3N6H6)·(C6H10O4)·H2O(1), C3H8N2O(3) and (H4btec)2·(4,4′-bipy)(4)(H4btec=1,2,4,5-benzenetetracarboxylic acid, 4,4′-bipy=4,4′-bipyridine) and one coordination supramolecular compound [Mn(C2O4)(H2O)2]·C6H11NO2(2) were synthesized by hydrothermal reaction. They were characterized by elemental analysis, infrared(IR) spectroscopy and single crystal X-ray diffraction(XRD). Structural analyses reveal that these 2D or 3D supramolecular networks of the compounds were formed by