Synthesis,characterization and catalytic performance of Mo based metal-organic frameworks in the epoxidation of propylene by cumene hydroperoxide

Two types of Mo containing metal-organic frameworks, denoted as Mo@COMOC-4 and PMA@MIL-101 (Cr), were synthesized respectively by a post-synthetic modification and a ship-in-bottle approach. The catalytic performance of both compounds in the epoxidation of propylene using cumene hydroperoxide (CHP) as oxidant was compared with MoO₃@SiO₂. A higher conversion (46.2%) and efficiency (87.4%) of CHP was observed for Mo@COMOC-4, whereas the heteropoly acids supported MIL-101 resulted in the decomposition of CHP due to its strong acidic character. Regenerability tests demonstrated that Mo@COMOC-4 could be reused for multiple runs without significant loss in both activity and stability. © 2017 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.     

Microporous aluminoborates with large channels: structural and catalytic properties

Channel zapping: PKU-1 and newly synthesized PKU-2 (Al(2)B(5)O(9)(OH)(3)?n?H(2)O; see picture) possess microporous structures with 18-ring and 24-ring channels, respectively. They show high reactivity and size selectivity in the cyanosilylation of aldehydes as heterogeneous Lewis acid catalysts. The different channel sizes determine the substrate selectivity. These examples demonstrate the potential of octahedron-based aluminoborate channels in catalysis.     

基于2,5-二溴对苯二羧酸配体的镧系金属有机骨架的合成、结构及性质

采用溶剂热法, 以2, 5-二溴对苯二甲酸(H₂L)为配体, 分别与六水合硝酸钕、六水合硝酸钆反应合成了 2种镧系金属有机骨架(MOFs):{[Nd₂(L)₃(DMF)₂(H₂O)₂]·2DMF}_n (1)和{[Gd₂(L)₃(DMF)₂(H₂O)₂]·2DMF}_n (2)。通过单晶X射线衍射、粉末X射线衍射、红外光谱、元素分析、荧光光谱、热重分析等测试方法对其进行了结构表征与性质研究。结果表明, 2个配合物均是以稀土离子为金属节点, 与配体相互连接, 形成无限延伸的三维网状结构。     

Construction of metal-organic frameworks through coordination and hydrogen bonding interactions: Syntheses, structures and photoluminescent properties of metal complexes with macrocyclic ligand

A macrocyclic ligand L with two diethylenetriamine units linked by two rigid biphenylene spacers was used as building block for construction of metal-organic frameworks. A silver(I) complex with macrocyclic and open-chain mix-type ligands [Ag₂(L)(L′)](ClO₄)₂ (1) [L′=1,6-bis(4-imidazol-1′-ylmethylphenyl)-2,5-diazahexane] was obtained by reaction of L and L′ together with AgClO₄·H₂O. It is interesting that the open-chain tetradentate ligand L′ only served as a bidentate ligand to bridge the Ag₂L units into an infinite one-dimensional (1D) cationic chain. Neutral 1D chain coordination polymer [Cu₂(L)(μ-SO₄)₂]·3H₂O·3MeOH (2) is formed by sulfate bridges between the neighboring Cu₂L units. When L reacted with nickel(II) sulfate instead of copper(II) sulfate, a monomacrocycle molecular complex [Ni₂(L)(H₂O)₄(SO₄)₂] (3) was obtained in which the sulfate anion acts as monodentate ligands rather than as bridges. When Cd(II) salts were used for the reactions with L, another two neutral 1D coordination polymers, [Cd₂(L)(μ-Cl)₂Cl₂]·2H₂O (4) and [Cd₂(L)(μ-Br)₂Br₂] (5), with the same structure were isolated. All the synthesized complexes exhibit three-dimensional framework structures linked by various hydrogen bonds. The photoluminescent properties of the synthesized complexes were studied in the solid state at room temperature, and the Ag(I) and Cd(II) complexes were found to show strong blue luminescence.     

基于2，5-二溴对苯二羧酸配体的镧系金属有机骨架的合成、结构及性质

采用溶剂热法,以2,5-二溴对苯二甲酸(H₂L)为配体,分别与六水合硝酸钕、六水合硝酸钆反应合成了2种镧系金属有机骨架(MOFs)：{[Nd₂(L)₃(DMF)₂(H₂O)₂]·2DMF}_n (1)和{[Gd₂(L)₃(DMF)₂(H₂O)₂]·2DMF}_n (2)。通过单晶X射线衍射、粉末X射线衍射、红外光谱、元素分析、荧光光谱、热重分析等测试方法对其进行了结构表征与性质研究。结果表明,2个配合物均是以稀土离子为金属节点,与配体相互连接,形成无限延伸的三维网状结构。     

Construction of three new metal-organic frameworks with distinct SBUs: trinuclear {Cd3(COO)6} clusters,inorganic -Cd-O-Cd- chains,and heterometallic trinuclear {Cd2Ba(COO)4} clusters

Three metal-organic frameworks (MOFs), [Cd₃(OABDC)₂(e-urea)₄]_n (1), [Cd₃(OABDC)₂(H₂O)₅)]_n (2) and [Cd₂Ba(OABDC)₂(H₂O)₇]_n (3) (H₃OABDC = 5-oxyacetate isophthalic acid, e-urea = 2-imidazolidinone), were prepared using H₃OABDC and metal salts. Single-crystal X-ray diffraction analyses reveal that 1 features a 2-D layered structure constructed from trinuclear {Cd₃(COO)₆} SBUs and represents a (3,6)-connected kgd topology. Compounds 2 and 3 are 3-D inorganic–organic hybrid frameworks; 2 employs infinite inorganic –Cd–O–Cd– chains as SBUs, whereas (3,6)-connected ant-type 3 employs heterometallic trinuclear {Cd₂Ba(COO)₄} clusters as SBUs. The structures of these three compounds indicate that the SBUs play an important role in the construction of MOFs. Moreover, the thermal stabilities and solid-state photoluminescent properties of these three compounds have also been investigated.     

Tuning the physisorption of molecular hydrogen: binding to aromatic,hetero-aromatic and metal-organic framework materials

We present a study on the binding properties of molecular hydrogen to several polar aromatic molecules and to a model for the metal-oxide corner of the metal organic framework materials recently investigated as promising supports for hydrogen storage. Density functional theory employing the Perdew Wang exchange-correlation functional and second order Møller-Plesset calculations are used to determine the equilibrium structures of complexes with molecular hydrogen and their stability. It is found that for most hetero-aromatics the edge sites for molecular hydrogen physisorption have stabilities comparable to the top sites. The DFT predicted binding energies compare favorably with those estimated at MP2 level, and get closer to the MP2 results for increased electrostatic contributions (induced by the polar aromatics) to the intermolecular interaction. Vibrational frequencies are also computed at the DFT level, and infrared activities of the H₂ stretching frequency are compared for the various complexes. Pyrrole, pyridine and n-oxide pyridine are predicted to form the more stable complexes among one-ring aromatics. The computed binding energies to metal-organic framework materials are in good agreement with experimental observations. It is suggested that replacement of the organic linker in MOF materials with some of the more efficient aromatics investigated here might contribute to enhance the H₂ storage properties of mixed inorganic–organic materials.     

一种新型三维配位聚合物的合成以及表征和磁性测定(英文)

通过水热法合成了三维(3D)网状金属有机框架物[Pr(NTA)(H2O)]n(NTA=nitrilotriacetic acid);利用元素分析、红外光谱分析、X射线单晶衍射等表征了产物的结构,利用热重分析和示差热重分析评价了其热稳定性,并测定了其磁性能.结果表明,目标配合物的Pr(Ⅲ)采取九配位模式(N1O8)形成三帽三角棱柱几何构型,配位聚合物通过O-C-O链组装成高度有序的3D结构.此外,合成的配合物具有较高的热稳定性,并因(O2C-C-C-CO2)2桥联而显示反铁磁性.     

Pillared, 3D metal-organic frameworks with rectangular channels. Synthesis and characterization of coordination polymers based on tricadmium carboxylates

Hydro(solvo)thermal reactions between cadmium(II) perchlorate and 4-pyridinecarboxaldehyde in the presence of various guest molecules have resulted in a series of 3-D coordination polymers based on tricadmium carboxylates [Cd6(isonicotinate)10(H2O)2](ClO4)2(EtOH)4(H2O)4, 1, [Cd3(isonicotinate)5 (EtOH)](ClO4)(EtOH)(4-nitroaniline)0.5, 2, and [Cd6(isonicotinate)11](ClO4)(EtOH)2(H2O)2(4-cyanopyridine)0.5, 3. X-ray single crystal structure determinations show that they exhibit similar pillared, 3D framework structures based on tricadmium carboxylate building blocks. Rectangular channels are clearly present in these polymeric networks and are occupied by perchlorate anions and disordered guest molecules. Quantitative NMR and X-ray powder diffraction studies and thermogravimetric analyses (TGA) reveal that these coordination networks are capable of accommodating different guest molecules. More significantly, the guest molecules can be readily removed via evacuation to result in nanoporous polymeric coordination networks retaining the framework structures of the pristine solids. Crystal data for 1: monoclinic space group P2(1)/n, a = 19.041(1) A, b = 23.654(1) A, c = 21.568(1) A, beta = 95.440(1) degrees, and Z = 4. Crystal data for 2: triclinic space group P1, a = 12.050(1) A, b = 12.277(1) A, c = 19.103(1) A, alpha = 91.669(1) degrees, beta = 96.850(1) degrees, gamma = 117.945(1) degrees, and Z = 2. Crystal data for 3: monoclinic space group P2(1)/n, a = 19.038(1) A, b = 23.834(1) A, c = 21.756(1) A, beta = 97.580(1) degrees, and Z = 4.     

Synthesis, characterization and properties of some metal(II) 5-(nicotinamido)isophthalate complexes

Four new complexes, {[M(NAIP)(H₂O)₄]·2H₂O}_n (M = Co (1), M = Mn (2)), {[Zn(NAIP)]·0.5H₂O}_n (3) and {Cd(NAIP)(H₂O)₂]·1.5H₂O}_n (4) [H₂NAIP = 5-(nicotinamido)-isophthalic acid] have been prepared and structurally characterized. The ligand NAIP²⁻ exhibits different coordination modes and leads to the formation of various architectures. Complexes 1 and 2 show a one-dimensional (1D) zigzag chain, where hydrogen-bonding interactions further link these chains to a three dimensional (3D) supramolecular structure. For complex 3, a 3D coordination network with a four-coordinated Zn(II) and NAIP²⁻ as a SBU was observed. Complex 4 presents a three-connected 2-fold interpenetrated 3D network with a (10, 3)-b net topology. Their luminescent and magnetic properties have been investigated in the solid state.     

Synthesis, crystal structure, and catalytic properties of MgCo6Ge6

The ternary compound MgCo6Ge6 represents a novel member of the RM6X6 phases, which contains a graphite-type Ge network, Kagomé nets of Co atoms, and Ge2 dumbbells with an unexpected short Ge-Ge contact in the range of a localized Ge-Ge single bond. The title compound shows a large variety of chemical bonding, which ranges from metallic to multicenter and covalent bonding. The role of polar intermetallic alloys as promising candidates for the application as catalysts for the selective hydrogenation of alpha,beta-unsaturated aldehydes is discussed. MgCo6Ge6 possesses a remarkable activity and selectivity for the hydrogenation of cis/trans-citral to geraniol and nerol.     

A microporous lanthanide metal-organic framework containing channels:Synthesis,structure,gas adsorption and magnetic properties

Under solvothermal condition,the reaction of furan-2,5-dicaboxylate(H2FDA) and glycol with Gd(NO3)3.6H2O gave microporous lanthanide metal-organic framework(MOF),{[Gd(FDA)1.5(glycol)].1.5H2O}}n(1).This compound was characterized by single crystal X-ray diffraction,infrared spectroscopy,elemental analysis,thermogravimetry analysis,and powder X-ray diffraction.The Gd(III) ions were connected by carboxylic group of FDA2-to give 1D chains,which were further linked by FDA2-,forming a 3D porous framework with 3D ...     

A series of metal-organic frameworks based on 9,10-bis(imidazol-1-ylmethyl)anthracene and structurally related aromatic dicarboxylates: Syntheses, structures, and photoluminescence

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.     

Hierarchical ZSM-11 with intergrowth structures: Synthesis,characterization and catalytic properties

Hierarchical ZSM-11 microspheres with intercrystalline mesoporous properties and rod-like crystals intergrowth morphology have been synthesized using a spot of tetrabutylammonium as a single template. XRD, FTIR, SEM, TEM and N₂ adsorption analysis revealed that each individual particle was composed of nanosized rod crystals inserting each other and the intercrystalline voids existing among rods gave a significant mesopore size distribution. Steam treatment result demonstrated the excellent hydrothermal stability of samples. Various crystallization modes including constant temperature crystallization (one-stage crystallization) and two-stage temperature-varying crystallization with different 1st stage durations were investigated. The results suggested that the crystallization modes were mainly responsible for the adjustable particle size and textural properties of samples while the small amount of tetrabutylammonium bromide was mainly used to direct the formation of both ZSM-11 framework and its intergrowth morphology. Furthermore, the performance of optimal ZSM-11 as an active component for the catalytic pyrolysis of heavy oil was also investigated. Compared with the commercial pyrolysis catalyst, the hierarchical ZSM-11 catalyst exhibited a high selectivity to desired products (LPG + gasoline + diesel), as well as a much lower dry gas and coke yield, plus a high selectivity and yield of light olefins ( ${\text{C}}_{\text{3}}^{=}-{\text{C}}_{\text{4}}^{=}$) and very poor selectivity to benzene. Therefore, fully open micropore-mesopore connectivity would make such hierarchically porous ZSM-11 zeolites very attractive for applications in clean petrochemical catalysis field.     

Rotamers of palladium complexes bearing IR active N-heterocyclic carbene ligands: Synthesis, structural characterization and catalytic activities

The preparation and properties of mono- versus bis(carbene) Pd(II) complexes bearing unsymmetrical cyano- and ester-functionalized NHC ligands as potential IR probes were studied in detail. Direct reaction of Pd(OAc)₂ with functionalized imidazolium salts afforded either bis(carbene) (3a, c) or monocarbene complexes (5, 6) with a N-coordinated imidazole co-ligand. The latter were exclusively obtained with N-ethylene substituted salts, which were found to undergo N-C cleavage reaction. The milder Ag-carbene transfer reaction on the other hand was tolerable to the length of the substituents and the nature of the functional groups. All bis(carbene) complexes (3a-c, 4a-c) were obtained as a inseparable mixture of square-planar trans-anti and trans-syn rotamers. The identity, ratio and dynamic equilibrium of these rotamers have been investigated and the relatively high rotational barrier for rotamers of 3a was estimated to be about 74 kJ mol⁻¹ at 380 K. All eight complexes were fully characterized by NMR and IR spectroscopies, ESI mass spectrometry and X-ray single crystal and powder diffraction. A preliminary catalytic study showed that ester-functionalized complexes 4a and 4b gave rise to highly active catalyst in the double Mizoroki-Heck coupling of aryl dibromides, while the in situ ester-hydrolyzed complexes were also active in the coupling of activated aryl chlorides.     

Synthesis,structure and catalytic properties of Pdii-based bimetallic complexes with ferrocenecarboxylic acid

Novel highly soluble palladium-based complexes with ferrocenecarboxylic acid of general formula [Pd(lut)₂(FcCOO)₂] (lut is 2,6-or 3,4-lutidines) were synthesized and structurally characterized by single-crystal X-ray diffraction. The catalytic oxidation of 1,2-diphenyl-acetylene with these complexes gave dibenzo[a,e]pentalene derivative along with other products.