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Hydrothermal reactions of N-auxiliary flexible exo-bidentate ligand 1,3-bis(4-pyridyl)propane (bpp) and carboxylates ligands naphthalene-2,6-dicarboxylic acid (2,6-H2ndc) or 4,4′-(hydroxymethylene)dibenzoic acid (H2hmdb), in the presence of cadmium(II) salts have given rise to two novel metal-organic frameworks based on flexible ligands (FL-MOFs), namely, [Cd2(2,6-ndc)2(bpp)(DMF)]·2DMF (1) and [Cd3(hmdb)3(bpp)]·2DMF·2EtOH (2) (DMF=N,N-Dimethylformamide). Single-crystal X-ray diffraction analyses revealed that compound 1 exhibits a three-dimensional self-penetrating 6-connected framework based on dinuclear cluster second building unit. Compound 2 displays an infinite three-dimensional ‘Lucky Clover’ shape (2,10)-connected network based on the trinuclear cluster and V-shaped organic linkers. The flexible bpp ligand displays different conformations in 1 and 2, which are successfully controlled by size-matching mixed ligands during the self-assembly process.

A new multifunctional enantiopure ligand, (S)-2-(1,8-naphthalimido)-3-(4-imidazole)propanoate (s-nip), containing a homochiral center derived from l-histidine and a strong π···π stacking 1,8-naphthalimide synthon, has been used to prepare three novel metal–organic frameworks. The frameworks of [Zn(s-nip)2]n (1) and {[Co(s-nip)2]·(H2O)0.5}n (2) are isostructural three-dimensional (3D) homochiral supramolecular structures organized one-dimensional (1D) ribbons by strong hydrogen bonds and π···π interactions, which display ferroelectric behavior at room temperature. The complex [Cu(nia)2·(H2O)5]n (3) was constructed under a hydrothermal in situ ligand synthesis reaction, in which the new ligand 2-(1,8-naphthalimido)-3-(4-imidazole)acrylate (nia) was formed from the s-nip ligand via a dehydrogenation reaction. The two-dimensional network of 3 stacks into a 3D structure via π···π interactions resulting in 1D hydrophilic channels.

Cubic boron nitride (cBN) is a excellent super hard materials with superior mechanical properties that has been widely used in different industrial applications. Conventional cBN was sintered with binder in the cBN powder, and the binder affect the mechanical properties of cBN. Here we report that we sinter the polycrystalline cBN on WC-16wt%Co substrates without any sintering agent at the pressure 5.5 GPa and temperatures of 1300-1600°C for 10 min. In the sintering, we used 1-2μm fine grained cBN powder as the starting materials, also, liquid substance infiltrated from the substrates and occurred chemical reactions with cBN powder. Reaction contents were investigated at different temperatures according to X-ray diffraction (XRD). Plenty of direct BN-BN bonding was formed in the scanning electron microscopy ( SEM) observation.The hardness of best samples reach 38.5 GPa under the loading force of 5 kg, which have high hardness for the formation of direct BN-BN fine grains in the sample. .

Two isomorphic 2D metal–organic coordination polymers, [Zn(bpndc)(H2O)]∞ (1) and [Cd(bpndc)(H2O)]∞ (2), have been hydrothermally prepared by exploring a semi-rigid V-type dicarboxylate ligand, benzophenone-4,4′-dicarboxylic acid (H2bpndc). Two complexes were characterized by single crystal X-ray diffraction, elemental analyses, IR spectrum, powder X-ray diffraction, thermal analyses, UV–Vis and fluorescence emission spectra. The metal ions in 1 and 2 are connected by carboxylate groups of bpndc to generate a 1D chain with doubly helical structures. The chains are linked by bpndc to form a 2D sinusoidal wavelike layer, which are further assembled with O–H⋯O hydrogen bonds to generate a 3D supramoleclar networks. The topology of 2D structure is an unusual flat (3,4)-connected net forming 4 and 6-gons with the Schlafli notation of (4·62)(42·62) (see Natarajan and Mahata, 2009 [14]).

A novel three-dimensional metal–organic framework, [Mn(pydc)(DMF)]n (1) (pydc = pyridine-3,4-dicarboxylate, DMF = N,N-dimethylformamide), has been hydrothermally synthesized and structurally characterized, which consists of one-dimension Mn(COO)2 chains and rhombic channels. The porous complex 1 displays a 4-connected ABW–zeolite topology with vertex symbols of 4.6.4.6.6.82, and exhibits high thermal stability (315 °C) and anti-ferromagnetic properties.

Two 3D noninterpenetrated pillar-layered metal–organic frameworks have been synthesized under solvothermal reactions based on a N,N′-di(4-pyridyl)-1,4,5,8-naphthalenetetracarboxydiimide (DPNDI) pillar. Single-crystal X-ray diffraction analyses revealed that compound [Co3(BDC)3(DPNDI)(DMF)2]·2CH3CN (1) displays an eight-connected hex net with Schlafli symbol 36·418·53·6 and consists of a DPNDI pillar and 2D 36 net layer that was constructed from a pinwheel trimetallic secondary building unit and 1,4-benzenedicarboxylate (BDC) linker. Compound [Zn2(HFIPBB)2(DPNDI)]·8DMF (2) exhibits a six-connected mab net with Schlafli symbol 44·610·8 and consists of a DPNDI pillar and 2D wavelike 44 net layer with helical channels that was constructed from a paddlewheel dimetallic secondary building unit and bent V-type 4,4′-(hexafluoroisopropylidene)bis(benzoate) linker. The phase purity, thermal stability, and N2 adsorption/desorption of 1 and 2 were measured; the antiferromagnetic property of 1 as well as the photochro...

Two novel Mg-based metal–organic framework isomers with the formula [Mg2(HCO2)2(NH2-BDC)(DMF)2]n (NH2-BDC = 2-amino-1,4-benzenedicarboxylate) have been synthesized based on a 6-connected [24-MC-6] metallacrown secondary building unit (SBU), which display a two-dimensional (2D) 36 net (1) and three-dimensional primitive rhombohedral net (2) derived from a different extended orientation of SBU, respectively. The 2D framework of 1 exhibits relevant thermal stability, solvents stability, high CO2 adsorption, and strong luminescent properties.

In this paper, three types of polycrystalline diamond (PCD) tools marked as PCD 030, PCD 010 and PCD 005 (equivalent to 30, 10, and 5μm average grain size of original diamond) were tested, and their wear behaviors was studied. The wear of PCD cutting tools in machining granite bars was invested by a turning process. The experiments were carried out under wet condition. Wear volume was measured by optical microscopy and wear morphology was examined by scanning election microscopy (SEM) and optical microscopy. By comparing the flank face, the experiments results show that the PCD tools with coarse original diamond grain size have long life at three cutting speeds, and the tool life of the three PCD tools decreases with the increase of cutting speed. SEM morphology by secondary electron image analysis indicates that the dominant wear mechanism for PCD 010 and PCD 005 is abrasive wear. While for PCD 030, the abrasive wear mechanism is predominant wear in the machining, occasionally some cleavage wear are also observed.

In this paper, we report the photoluminescence from high-quality nanocrystalline ZnO thin films. The high-quality nanocrystalline ZnO thin films are prepared by thermal oxidation of ZnS films at 800℃, which are deposited by low-pressure metal-organic chemical vapor deposition technique. X-ray diffraction indicated that the nanocrystalline ZnO thin films have a polycrystalline hexagonal wurtzite structure. A strong ultraviolet emission peak at 3.26 eV was observed and the deep-level emission band was barely observable at room temperature. The strength (ΓLO) of the exciton-longitudinal-optical (LO)-phonon coupling is deduced from the temperature dependence of the full width at half maximum of the fundamental excitonic peak. ΓLO is reduced greatly due to the quantum confinement effect.