Search

Objective: Testicular fat deposition has been reported to affect animal reproduction. However, the underlying mechanism remains poorly understood. The present study explored whether sperm meiosis and testosterone synthesis contribute to mouse testicular fat depositioninduced reproductive performance. Methods: High fat diet (HFD)-induced obesity CD1 mice (DIO) were used as a testicular fat deposition model. The serum hormone test was performed by agent kit. The quality of sperm was assessed using a Sperm Class Analyzer. Testicular tissue morphology was analyzed by histochemical methods. The expression of spermatocyte marker molecules was monitored by an immuno-fluorescence microscope during meiosis. Analysis of the synthesis of testosterone was performed by real-time polymerase chain reaction and reagent kit. Results: It was found that there was a significant increase in body weight among DIO mice, however, the food intake showed no difference compared to control mice fed a normal diet (CTR). The number of offspring in DIO mice decreased, but there was no significant difference from the CTR group. The levels of follicle-stimulating hormone were lower in DIO mice and their luteinizing hormone levels were similar. The results showed a remarkable decrease in sperm density and motility among DIO mice. We also found that fat accumulation affected the meiosis process, mainly reflected in the cross-exchange of homologous chromosomes. In addition, overweight increased fat deposition in the testis and reduced the expression of testosterone synthesis-related enzymes, thereby affecting the synthesis and secretion of testosterone by testicular Leydig cells. Conclusion: Fat accumulation in the testes causes testicular cell dysfunction, which affects testosterone hormone synthesis and ultimately affects sperm formation. [ABSTRACT FROM AUTHOR]

Long term thermal stability and temperature induced ageing mechanisms of different solar absorber coatings are investigated in this study. These coatings are chromium, chromium nitride and chromium oxynitride based coatings on aluminium substrate. The coatings were annealed at 278 °C for 600 h during the first round test. The second round test was performed at 308 °C for 342 h. An additional test at 400 °C for 200 h is designed for the sake of obtaining more degradation information. Thermal stability, microstructure, composition distribution, element diffusion and oxidation were studied using UV/VIS/NIR spectrophotometer, FTIR spectrometer, scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and Auger electron spectroscopy (AES) respectively. The result shows that the main ageing mechanism is diffusion and oxidation of Cr, Al, N and O. And the microstructure defects, such as enlarged grain boundaries, micro cracks and holes, act as a facilitating role during the ageing process because they provide fast diffusion paths for short-circuit diffusion. [ABSTRACT FROM AUTHOR]

In this paper, we are concerned with a class of Schrödinger-Poisson systems with the asymptotically linear or asymptotically 3-linear nonlinearity. Under some suitable assumptions on V, K, a, and f, we prove the existence, nonexistence, and asymptotic behavior of solutions via variational methods. In particular, the potential V is allowed to be sign-changing for the asymptotically linear case. [ABSTRACT FROM AUTHOR]

Mucus lubricants are widely distributed in living organisms. Such lubricants consist of a gel structure constructed by associative mucin. However, limited tribological studies exist on associative mucin fluids. The present research is the first to investigate the frictional behavior of a typical intact vertebrate mucin (loach skin mucin), which can recover the gel structure of mucus via hydrophobic association under physiological conditions (5-10 mg/mL loach skin mucin dissolved in water). Both rough hydrophobic and hydrophilic polydimethylsiloxane (PDMS) rubber plates were used as friction substrates. Up to 10 mg/mL loach skin mucin dissolved in water led to a 10-fold reduction in boundary friction of the two substrates. The boundary-lubricating ability for hydrophilic PDMS decreased with rubbing time, whereas that for hydrophobic PDMS remained constant. The boundary-lubricating abilities of the mucin on hydrophobic PDMS and hydrophilic PDMS showed almost similar responses toward changing concentration or sodium dodecyl sulfate (SDS). The mucin fluids reduced boundary friction coefficients (μ) only at concentrations (c) in which intermucin associations were formed, with a relationship shown as μ ~ c-0.7. Destroying intermucin associations by SDS largely impaired the boundary-lubricating ability. Results reveal for the first time that intermolecular association of intact mucin in bulk solution largely enhances boundary lubrication, whereas tightly adsorbed layer plays a minor role in the lubrication. This study indicates that associated mucin should contribute considerably to the lubricating ability of biological mucus in vivo. [ABSTRACT FROM AUTHOR]

Selective adsorption and separation of CO2 are of great importance for different target applications. Metal–organic frameworks (MOFs) represent a promising class of porous materials for this purpose. Here we present a unique MOF material, [Cu(tba)2]n (tba = 4-(1H-1,2,4-triazol-1-yl)benzoate), which shows high CO2 adsorption selectivity over CH4/H2/O2/Ar/N2 gases (with IAST selectivity of 41–68 at 273 K and 33–51 at 293 K). By using a critical point dryer, the CO2 molecules can be well sealed in the 1D channels of [Cu(tba)2]n to allow a single-crystal X-ray analysis, which reveals the presence of not only Cδ+—H···Oδ− bonds between the host framework and CO2 but also quadrupole–quadrupole (CO2δ−···δ+CO2) interactions between the CO2 molecules. Furthermore, [Cu(tba)2]n will suffer divergent kinetic and thermodynamic hydration processes to form its isostructural hydrate {[Cu(tba)2](H2O)}n and a mononuclear complex [Cu(tba)2(H2O)4] via single-crystal to single-crystal transformations. [ABSTRACT FROM AUTHOR]

Reaction of Ph2SnCl2 with 1,3-bis(3,5-dimethylpyrazol-1-yl)-2-propanol (L) in a 1:1 ratio yields L(SnPh2Cl2)2 adduct, which partly hydrolyzes to the title complex (C25H31Cl3N4OSn, Mr = 628.58) during crystal growing in the air. The title complex is of monoclinic, space group P21/n with a = 9.0338(9), b = 17.890(1), c = 17.340(1) Å, β = 95.533(1)o, V = 2798.9(5) Å3, Z = 4, Dc = 1.492 Mg/m3, λ(Mo Kα) = 0.71073 Å, μ = 1.224 mm−1, F(000) = 1272, R = 0.023, wR = 0.054 for 4212 observed reflections with I ≥ 2σ( I). The crystal structure indicates that there is no direct interaction between the pyrazolyl ligand and the tin atom, but this complex forms a supramolecular structure through weak intermolecular C–H⋯Cl and O–H⋯Cl hydrogen bonds. Reaction of Ph2SnCl2 with 1,3-bis(3,5-dimethylpyrazol-1-yl)-2-propanol (L) in a 1:1 ratio yields L(SnPh2Cl2)2 adduct, which partly hydrolyzes to (PzCH2CHOHCH2PzH)·(Ph2SnCl3) (Pz = 3,5-dimethylpyrazol-1-yl) during crystal growing in the air. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

This work presents eight coordination assemblies based on divalent metal ions (M = CoII, CuII, ZnII, and CdII), dicyanamide anion (N(CN)2−, dca), and two isomeric bent dipyridyl coligands (L), namely, 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (3-bpo) and 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (4-bpo). In the resulting crystalline materials, both bpo and dca tectons generally display the bidentate bridging fashion (except in the mononuclear species 5), extending the metal centers to afford diverse one-, two-, and three-dimensional (1-D, 2-D, and 3-D) coordination networks that are not commonly observed in M−dca−L systems. Notably, the inclined polycatenated 2-D → 3-D framework and 3-D polyknotting network with the unique 6-connected (44.611) topology are formed for the CuIIand CdIIspecies with dca and 4-bpo. For the polymeric CoIIand CuIIcomplexes, very weak antiferromagnetic or ferromagnetic interactions are observed between the metal centers due to the μ1,5-bridging mode of dca, and their magneto-structural correlations have been discussed in detail. The ZnIIand CdIIcomplexes show solid-state fluorescent emissions at room temperature. [ABSTRACT FROM AUTHOR]

Reaction of isonicotinic acid N-oxide (HINO) with AgClO4or AgBF4under similar conditions unexpectedly generates two distinct crystalline products {[Ag3(INO)2(HINO)2]·(ClO4)}n(1) and {[Ag(INO)]·(H2O)}n(2). Complex 1consists of a 3-D cationic net with mixed-connected topology and the included perchlorate counterions, whereas 2has a 3-D neutral open framework (4-connected crbtopology) with the accommodation of lattice water. The anion exchange/competition and guest desorption/adsorption behavior have also been thoroughly explored. [ABSTRACT FROM AUTHOR]

Co-crystallization of a versatile building module 4-amino-3,5-bis(4-pyridyl)-1,2,4-triazole (4-bpt) with isophthalic acid (H2ip) and its 5-substituted derivatives R–H2ip (R = –NH2, –SO3H, and –CO2H) affords a series of supramolecular solids 1–5. All compounds have been characterized by IR, microanalysis, and powder X-ray diffraction, and their thermal stability has been investigated by TG-DTA technique. Single crystal X-ray diffraction reveals that compounds 1and 2with the formula [(H2ip)·(4-bpt)] exhibit polymorphism, which can be isolated viaa similar synthetic procedure without or with the metal ion as structure-directing reagent, and display distinct hydrogen-bonding assemblies of 3-D and double-layer networks, respectively. Multifarious 3-D supramolecular architectures are observed for compounds [(NH2–H2ip)·(4-bpt)] (3), [(SO3–H2ip)−·(H-4-bpt)+]·2H2O (4), and [(CO2H–H2ip)·(4-bpt)]·2H2O (5), in which the substituent groups of isophthalic acid are involved in different hydrogen-bonding interactions. The results clearly display the substituent effect on the structural assembly of organic co-crystals, which will be significant in the rational design and construction of such crystalline materials with specific hydrogen-bonding networks. [ABSTRACT FROM AUTHOR]

This work presents a series of coordination polymers with a dipyridyl-type building block bis[3,5-dimethyl-4-(4′-pyridyl)pyrazol-1-yl]methane (pypz) and different anionic co-ligands. The elongated and flexible backbone of the pypz ligand facilitates the formation of diverse entangled coordination networks, which are well regulated by the auxiliary anionic components. Generally, the anions of nitrate, chloride, and pseudohalide (such as dicyanamide, thiocyanate, and azide) display a monodentate binding mode in this system and serve as terminal pendants of the metal–pypz coordination layers. As a result, 2D → 3D polythreading architectures are mostly observed, except in the case of small chloride anion that leads to twofold parallel interpenetration of the layers. On the other hand, the aromatic dicarboxylates such as terephthalate and biphenyl-4,4′-dicarboxylate behave as rod-like linkers for the construction of diversiform 2D or 3D interpenetrated coordination networks with the aid of pypz. Besides, these crystalline materials may also be significantly affected by other assembled elements such as metal ion, solvent, and metal-to-ligand ratio. [ABSTRACT FROM AUTHOR]

This work presents the structural assemblies of a series of coordination polymers by utilizing the familiar metal ions with two flexible and versatile pyridylcarboxylate derivative ligands as anionic building blocks, namely, 5-(4-pyridyl)-1,3,4-oxadiazole-2-thioacetate and its 3-N-pyridyl isomer. These complexes display multifarious polymeric coordination frameworks, such as the 1-D double-strand chain, 2-D homochiral layer, as well as 3-D (3,6)-connected networks with anatase or rutile topology, in which the unsymmetric organic modules may serve for two-connected spacers (for 1-D and 2-D species) or three-connected nodes (for 3-D species) with dissimilar coordination modes and configurations. Apparently, the metal centers also play a critical role in facilitating the structural diversity by adopting different network linkages. Hydrogen-bonding contacts are generally found to extend and/or stabilize the overall crystalline lattices when aqua molecules are available. [ABSTRACT FROM AUTHOR]

A series of nine CoII, CuII, and CdII mixed-ligand coordination complexes with a 3,3′-dipyridyl connector 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole (3-bpt) have been achieved, by changing the incorporated benzenedicarboxylic co-ligands from isophthalic acid (H2ip) to its 5-substituted derivatives 5-nitroisophthalic acid (–NO2, H2nip) and trimesic acid (–COOH, H3tma). All compounds have been structurally determined by the X-ray diffraction technique. It is indicated that most of them are coordination polymers, with the ligands of benzenecarboxylic acids being doubly deprotonated to compensate the charge and bridge the metal ions, except for a monomeric ion-pair product [Co(3-bpt)2(H2O)4]·(H2tma)2·(H2O)2 (1c). These polymers display a variety of coordination frameworks, such as 1-D double-strand chain, 2-D layer with (4,4) topology, 2-D double layer, 2-D layer with (6,3) topology and 1-D molecular ladder etc. The results evidently reveal the profound substituent effect of the R-isophthalate building blocks on engineering such coordination arrays, in virtue of the versatility of 3-bpt with diversiform configurations and binding fashions. Nevertheless, the choice of metal ion is also significant in the structural assembly, and the low-dimensional coordination networks are further extended to diverse 3-D supramolecular crystalline lattices via noncovalent interactions especially hydrogen bonding. Solid-state properties such as thermal stability and fluorescence have also been investigated. [ABSTRACT FROM AUTHOR]

This work presents a systematic investigation on coordination chemistry of a pharmaceutical agent pamoic acid (H2PA), and also reveals the significant function of supramolecular interactions in managing the resultant crystalline networks with the incorporation of secondary co-ligands. Assemblies of pamoic acid with transition metal ions under similar conditions yield a series of eleven MnII, CuII, ZnII, and CdII complexes, in the absence/presence of the organonitrogen ligands such as 2,2′-bipyridyl (2,2′-bipy), 1,10-phenanthroline (phen), and 4,4′-bipyridyl (4,4′-bipy). These compounds, together with the DMF solvate of pamoic acid, have been characterized by IR, elemental analysis, and single-crystal X-ray diffraction techniques. Generally, these complexes display similar 1-D pamoate-bridged coordination arrays (or 2-D coordination layers by introducing bridging 4,4′-bipy). Remarkably, distinct extended network architectures are further constructed with the aid of weak secondary interactions especially aromatic stacking. Amongst them, complexes 6, 8, 9, and 12, which exhibit unusual interpenetrating networks of (6,3) layers or 3-D 5-connected frameworks regulated by stacking forces, are representative paradigms of this research. Structural evolution under the co-ligand intervention in this series of complexes, as well as the general coordination rule of pamoate, has been further discussed. Thermal stability of these crystalline materials and fluorescent properties of the polymeric ZnII and CdII complexes have also been explored. [ABSTRACT FROM AUTHOR]

We study the friction behaviors of poly(vinyl alcohol) (PVA) gel sliding against glass surface in dilutepoly(ethylene oxide) (PEO) aqueous solution with various molecular weights, Mw, and concentrations. At low sliding velocity (10-5, 10-4m/s), distinct PEO polymer effects are observed:  The frictional stress in PEO 2E4 (Mw2 × 104g/mol) solutions is lower than that in pure water, decreasing with the increase in PEO concentration and reaching a minimum at the crossover concentration, c. However, in higher molecular weight solution, PEO 4E6 (Mw4 × 106g/mol), this friction reduction effect is only observed for very dilute concentration (0.01csolution), and the friction stress in higher concentration (0.1c, 0.3c, and csolution) is higher than that in pure water, accompanied by the appearance of “plateau”. At fast sliding velocity (10-2, 10-1m/s), all the friction curves in dilute PEO solution superpose with the curve in pure water, independent of Mwand concentration of PEO. These results indicate that in the low sliding velocity region, where adsorption of PVA gel on glass plays the dominant role in friction, PEO chain screens the adsorption of PVA chains to glass surface. In the fast sliding velocity region, PEO chain is either extensively stretched or forms a deplete layer on the glass surface by the high shear rate, so the liquid lubrication with a viscosity of waterprevails. The results also support the theoretical prediction that the effective concentration of PEO in the confined 2-dimentional space between gel and glass interface is enhanced for high molecular weight PEO. [ABSTRACT FROM AUTHOR]

A series of nine mixed-ligand metal-organic frameworks (MOFs) have been prepared by the combination of a bent dipyridyl linker 4-amino-3,5-bis(4-pyridyl)-1,2,4-triazole (bpt) and three benzenedicarboxylate isomers (pa = phthalate, ip = isophthalate, and tp = terephthalate), respectively, with different metal ions such as CoII, NiII, CuII, ZnII, and CoII. The framework structures of these neutral polymeric complexes have been determined by the X-ray single- crystal diffraction technique. Structural analysis reveals that the benzenedicarboxylate isomers display versatile coordination modes to manage the metal ions to form 1-D chain or ribbon arrays, which are further extended via the exo-bidentate bpt connectors to give rise to a variety of coordination networks, such as a simple (4,4) layer, 2-D double layer with decorated (4,4) topology, 2-D layer with decorated (3,6) topology, 2-D bilayer with 8².10 topology (2-fold interpenetration), 3-D polythreaded architecture (1-D + 2-D), and 2-fold interpenetrating porous lattice of (4,4) layers. The accessorial secondary interactions such as hydrogen bonding and/or aromatic stacking are also helpful for the extension and stabilization of the final supramolecular aggregates. This work evidently indicates that the isomeric effect of the anionic benzenedicarboxylate is significant in the construction of these network structures, which are also well regulated by the metal centers. The ZnII and CdII MOFs exhibit strong solid-state luminescence emissions at room temperature, which originate differently from intraligand transition or ligand-to-metal charge transfer. Thermal stability of these crystalline materials has been explored by thermogravimetric analysis of mass loss. The 3-D host frameworks of MOFs 8 and 9 show similar porous cavities, and their desorption/ adsorption behaviors of guest solvents have also been investigated. [ABSTRACT FROM AUTHOR]

Two new flexible dipyridyl building blocks, N,N‘-bis(4-picolinoyl)hydrazine (4-bph) and its N-orientation isomer N,N‘-bis(3-picolinoyl)hydrazine (3-bph), have been synthesized as versatile cocrystallizing agents and introduced into the reactions with pyromellitic acid (H4BTA) and fumaric acid (H2Fa). Hydrogen-bonded directed assemblies of two hydrates of bphs and four binary cocrystals were validated by single-crystal X-ray diffraction analysis. With the presence of the reliable hydrogen-bonding donor/acceptor(s) of bph, the crystalline lattices of 4-bph·2H2O (1) and 3-bph·2H2O (4) are managed by N−H···Owaterand O−H···Ocarbonylto afford one-dimensional (1D) arrays, which are further extended to distinct three-dimensional (3D) (for 1) and two-dimensional (2D) (for 4) networks via O−H···Npyridylinteractions. While for the concomitant polymorphs (H2BTA)·(H2-4-bph) (2and 3), charge-assistant bifurcated N−H···O bonds do favor 1D acid−base hydrogen-bonding tapes, which are interlinked to result in a 2D layer in 2and a 3D network in 3through the competition of O−H···Ocarboxyland O−H···Ocarbonylforces. (H3BTA)2·(H2-3-bph)·4H2O (5) is also a charge-transfer organic salt with a 2D bilayered array. Proton transfer from weak H2Fa to 3-bph is not observed, and this leads to the formation of a binary neutral cocrystal (H2Fa)·(3-bph) (6), in which the 2D undulating herringbone pattern is constructed via the expected carboxylpyridyl heterosynthon and amide−amide homosynthon. [ABSTRACT FROM AUTHOR]

Four novel ZnII and CdII metal-organic coordination polymers with a versatile building block 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol (Hpyt) have been prepared under different conditions. (Zn3(pyt)4(OH)2]n (1) and [Cd(pyt)(HCOO)]n (3) were obtained through a solvothermal method, whereas {[Zn(pyt)2(H2O)2]•(DMF)2}n (2) and {[Cd(pyt)2]CHCl3}n (4) were isolated under general conditions. X-ray single-crystal diffraction indicates that the anionic ligand pyt adopts a thioamide isomer in 1, 2, and 4, but a thiolate form in 3. Four types of binding modes involving monodentate (η-Noxa), bidentate (μ-Npy,Noxa, or μ-NpyS,S) and tridentate (μ-Npy,Noxa,S) are observed. The discrepancy of the synthetic routes and metal-coordination preferences facilitates the production of the final crystalline materials with distinct network structures, including a 1D zigzag array of 1 with dangling arms, a common 2D (4,4) coordination layer of 2, a decorated 3D α-Po network of 3, and an unprecedented (3,6)-connected 3D framework of 4 with a (4².6)2(4².6².87.10²) topology. Notably, the hydrolysis of DMF solvates leads to the formation of formate ions, being a component in the structure of 3. Complexes 2 and 4 show 1D channels in which the solvates are accommodated, and even after the exclusion of these guests, the porous host frameworks are still retained. Thermal stability and gas adsorption properties have also been studied. [ABSTRACT FROM AUTHOR]

A series of new metal-organic polymeric complexes, {[Co(bpt)(Htma)(H2O3]·2.25H2O}n (1), [Co(bpt)(Htma)(H2O)]n (2), [Ni(bpt)(Htma)(H2O)]n (3), [Zn(bpt)2(H2tma)2·6H2O (4), {[Cd(bpt)(Htma)(H2O)]·(C2H5OH)(H2O)1.5}n (5), and {-[Cd(bpt)(Htma)(H2O)2]·5.5H2O}n (6), was prepared from solution reactions of 4-amino-3,5-bis(4-pyridyl)-1,2,4-triazole (bpt) and trimesic acid (H3tma) with different metal salts under diverse conditions. All these compounds were structurally determined by X-ray single-crystal diffraction, and the bulk new materials were further identified by X-ray powder diffraction. Complexes 1 and 6 show 1-D zigzag or linear Htma-bridged polymeric chains, with the terminal bpt ligands as pendants, which are extended to 2-D hydrogen-bonded arrays with 4.82 or (6,3) network topology. Coordination polymers 2 and 3, in which the 2-D corrugated metal-organic frameworks make the interdigitated 3-D packing, are isostructural. Complex 4 has a mononuclear structure, and its subunits are hydrogen-bonded to each other to give a 2-D gridlike net. For complex 5, the CdII centers are linked by bpt/Htma ligands to form a 2-D (4,4) coordination layer, and these layers are interdigitated in pairs. Notably, secondary noncovalent forces, such as hydrogen bonds, play an important role in extending and stabilizing these structural topologies. Interestingly, distinct products are obtained for CoII (1 and 2) and CdII (5 and 6) under ambient or hydrothermal conditions; however, for NiII and ZnII, single products, 3 and 4, are generated. The thermal stabilities of 1-6 were studied by thermogravimetric analysis of mass loss. The desorption/adsorption properties of the porous material 5 are also discussed. Solid-state luminescent spectra of the ZnIIand CdII complexes, 4-6, indicate intense fluorescent emissions at ca. 380 nm. [ABSTRACT FROM AUTHOR]

A bent dipyridyl compound, 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (4-bpo), was employed to crystallize with 1,4-cyclohexanedicarboxylic acid (H2chdc), hydroquinone, citric acid (H4ca·H2O), barbituric acid, and ferrocene dicarboxylic acid (H2Fc) under general conditions, affording binary cocrystals [(H2chdc)·(4-bpo)] (1), [(hydroquinone)·(4-bpo)2] (2), [(H4ca)·(4-bpo)] (3), [(barbituric acid)·(4-bpo)] (4), and [(HFc)·(H-4-bpo)] (5) in high yield. X-ray single-crystal structures of these compounds reveal that a supramolecular synthon [%@mt;sys@%R%@sx@%2%@be@%2%@sxx@%%@mx@%(7)] containing classical O−H···N and weak C−H···O interactions, usually observed in organic cocrystals of carboxylic acid and heterocyclic base, is again involved in constructing the hydrogen-bonding networks of 1, 3, and 5. Its ionic analogous synthon [consisting of strong N−H···O and weak C−H···O/C%@mt;sys@%R%@sx@%2%@be@%2%@sxx@%%@mx@%(7)] also appears in the partly charge-transfer salt 5. For 2, only hydroxyl of the hydroquinone component can act as the hydrogen-bonding contributor, giving a strong O−H···N bond with 4-bpo. Multiple hydrogen-bonded donating/accepting sites in compound 3 saline 86.3 +/- 34.3 nmol/L per milligram of tissue per hour;4, another heterosynthon ring [containing strong N−H···N and weak C−H···O/C%@mt;sys@%R%@sx@%2%@be@%2%@sxx@%%@mx@%(7)] is formed due to the presence of the imide functional group. As a consequence, robust hydrogen-bonding interactions in these compounds afford diverse 2-D waved or planar layers (1 or 4), 1-D extended tape (2), 3-D net (3), and 1-D molecular-box type (5) supramolecular architectures. Thermal stability of these compounds has been investigated by thermogravimetric analysis (TGA) of mass loss. [ABSTRACT FROM AUTHOR]

The formation, crystal structures, and properties of a series of three-dimensional (3-D) CuII coordination polymers, {[Cu(L)2(H2O)2](PF6)2(H2O)1.25}n (1), {[CuL(N3)2](H2O)1.5}n (2), and {[CuL(H2O)(SO4)](H2O)2}n (3), with an angular bridging ligand 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (L) are reported. Complex 1 crystallizes in the tetragonal /41/a space group (a = b = 13.462(2) Å, c = 46.47(1) Å, Z = 8), complex 2 in the orthorhombic Pna21 space group (a = 6.379(2) Å, b = 10.060(3) Å, c = 27.232(9) A, Z = 4), and complex 3 in the orthorhombic P212121 space group (a = 5.510(2) Å, b = 10.576(4) ,Å, c = 28.34(1) Å, Z = 4). Different polymeric frameworks are obtained by only varying the counterions. These include the 2-fold interpenetrated diamondoid structure of 1, the acentric α-Po network of 2, and the chiral open framework of 3 with (6³).(69.8) topology. The interesting anion-exchange, porous, and magnetic properties of these coordination supramolecules have been investigated in detail. [ABSTRACT FROM AUTHOR]

The reaction of various Cu[sup II] salts with 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (L)in CH[sub 3]CN-H[sub 2]O medium affords different complexes, the solid structures of which are controlled only by the choice of the counteranions. Reaction of Cu(ClO[sub 4])[sub 2]·6H[sub 2]O or Cu(NO[sub 3])[sub 2]·3H[sub 2]O and L yields the novel bimetallic macrocyclic complex [Cu[sub 2]L[sub 2](H[sub 2]0)[sub 6]](CIO[sub 4])[sub 4](H[sub 2]0)[sub 4] (1) [monoclinic, space group P2[sub 1]/m, a = 8.745(5) Å, b = 16.179(10) Å, c = 14.930(8) Å, β = 93.253(10)°, Z = 2] or [CuL(NO[sub 3])[sub 2]][sub 2](CH[sub 3]CN)[sub 2] (2) [triclinic, space group P&1macr;, a = 7.863(3) Å, b = 8.679(3) Å, c = 13.375(5) Å, α = 74.121(5)°, β = 78.407(6)°, γ = 86.307(6)°, Z = 1]. However, with the replacement of Cu[sup II] perchlorate or nitrate salts with CuSO[sub 4]·5H[sub 2]O or Cu(OAc)[sub 2]·H[sub 2]O in the above reaction, two different one-dimensional (1-D) coordination polymers {[Cu[sub 2]L[sub 2](H[sub 2]O)[sub 6](SO[sub 4])[sub 2]](H[sub 2]O)[sub 6]}[sub n] (3) [triclinic, space group P&1macr;, a = 7.078(3) Ā, b = 11.565(4) Å, c = 12.561(5) Å, α = 109.511(6)°, β = 105.265(6)°, γ = 94.042(6)°, Z= 1] or {[Cu[sub 2]L(µ-OAc)[sub 4]]},[sub n](4)[monoclinic, space group C2/c, a = 20.007(7) Å, b = 7.506(2) Å, c = 16.062(5) Å, β = 108.912(5)°, Z = 4] were obtained. These results unequivocally indicate that the nature of the counteranions, which play different roles in each complex, is the key factor governing the structural topologies of them. The magnetic properties of these Cu[sup II] complexes have been investigated by variable-temperature magnetic susceptibility and magnetization measurements, and the magneto-structural correlation has been analyzed in detail. [ABSTRACT FROM AUTHOR]

Examines the crystal structure with three-dimensional coordination of polymer with angular dipyridyl ligand. Discussion on the magnetic properties and anion effects; Degree of interpenetration of diamondoid networks; Integration of diffraction profiles.

Investigates the varying coordination modes and magnetic properties of copper(II) complexes with diazamesocyclic ligands by altering additional donor pendants on 1,5-diazacyclooctane. Syntheses of ligands; Description of the crystal structures; Binuclear, trinuclear and polymeric complexes; Electronic spectra.

Discusses the mechanism of sperm-egg recognition during subzonal (perivitelline space) insemination, with reference to a study conducted on the issue. Details on three existing kinds of microinsemination techniques; Methodology used to conduct the study; Results of the study.

This work presents a mesoporous DyIII metal--organic framework with two types of void cages (diameters: 4.4 and 2.8 nm), which can efficiently adsorb a variety of chemical pollutants, including toxic metals, iodine, and formaldehyde. [ABSTRACT FROM AUTHOR]

The reaction of copper(II) nitrate, oxamide, and an angular bridging ligand 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (4-bpo) under hydrothermal conditions affords a 3D pillared-layer coordination framework {[Cu2(4-bpo)(ox)2](H2O)4}n (1) (ox = oxalate), featuring the unique zeolite-type NiP2 network and interesting properties. [ABSTRACT FROM AUTHOR]

Assembly of pamoic acid (H2PA) with piperazine (PIPO) or 4,4′-bipyridyl (BIPY) results in two distinct supramolecular complexes [(PA)·(H2PIPO)]·3H2O (1) and [(H2PA)·(BIPY)] (2). The former displays triple-helix host arrays via charge-assisted N+−H···O−interactions with the inclusion of helical water chains, whereas the latter represents the first cocrystal of pamoic acid sustaining by the familiar carboxyl-pyridyl H-bonding synthons. Notably, the structure of 1can be dehydrated/rehydrated with retention of crystallinity. [ABSTRACT FROM AUTHOR]

The combination of biphenyl-4,4′-dicarboxylic acid (H2bpa) and the bent dipyridyl base 2,5-di-4-pyridyl-1,3,4-oxadiazole (4-bpo) in a 1:1 molar ratio leads to the formation of the mol­ecular cocrystal (H2bpa)·(4-bpo) or C14H10O4·C12H8N4O. The asymmetric unit contains one-half of an H2bpa unit lying across a centre of inversion and one-half of a 4-bpo mol­ecule lying across a twofold rotation axis. Inter­molecular O—H⋯N inter­actions connect the acid and base mol­ecules to form a one-dimensional zigzag chain. Through further weak C—H⋯O hydrogen bonds between adjacent chains, a two-dimensional sheet-like supramolecular network is afforded. As an extended analogue of terephthalic acid (H2tp), the backbone geometry of H2bpa has an evident influence on the hydrogen-bonding pattern of the title cocrystal compared with that of (H2tp)·(4-bpo). [ABSTRACT FROM AUTHOR]

The mol­ecular structure of the neutral mononuclear title complex, [Mn(NCS)2(C12H8N4O)2(H2O)2], is centrosymmetric; the MnII atom lies on an inversion center and is six-coordinate (MnN4O2), with an octa­hedral geometry comprising two trans monodentate 2,5-di-3-pyrid­yl-1,3,4-oxadiazole ligands, two thio­cyanate ligands and two bound water mol­ecules. Inter­molecular O—H⋯N hydrogen bonds between these monomeric units result in two-dimensional supramolecular layers with a parallel arrangement, which are stabilized by intra­layer aromatic stacking and further extended to a three-dimensional network via inter­layer weak C—H⋯S inter­actions. [ABSTRACT FROM AUTHOR]

In the crystal structure of the title complex, [Cu(bda)(bipy)2]·4H2O [H2bda = ( p-phenyl­ene­dioxy)­di­acetic acid or benzene-1,4-dioxy­acetic acid (C10H10O6) and bipy = 2,2′-bi­pyridine (C10H8N2)], the CuII centre is pentacoordinated, with a square-pyramidal geometry comprising four N atoms from two chelating bipy ligands and one carboxyl­ate O atom of the bda ligand. The other three uncoordinated carboxyl­ate O atoms of the bda ligand act as the acceptors of four O—H⋯O hydrogen bonds from the water molecules, among which another four O—H⋯O hydrogen-bonding interactions are also observed, resulting in a two-dimensional supramolecular pattern. [ABSTRACT FROM AUTHOR]

The article focuses on the crystallization of the compound hexaquacobalt(II) bis(isonicotinate N-oxide). A redetermination and analysis of the hydrogen-bonding interactions was done. In the crystal structure of the complex the cobalt center is in an elongated octahedral environment composed of six coordinated water molecules. In the experiment isonicotinic acid nitrogen oxide was dissolved in methanol. Pink block-like single crystals were obtained.

The article focuses on the crystallization of the compound μ-Acetato-di-μ-hydroxo-bis{acetato[bis(2-pyridyl)-amine] cobalt(III)} acetate tetrahydrate. It is a novel mixed-bridged dinuclear Co(III) complex with bis(2-pyridyl)amine as terminal ligands. In the crystal structure each cobalt ion has an approximate octahedral geometry, coordinated by two pyridyl nitrogen atoms of the terminal bpa ligand. Well defined block-shaped single crystals of the title complex were formed in the experiment.

Examines the three-dimensional hydrogen-bonding supramolecular architecture of 2-(3-pyridinio)-5-(3-pyridyl)-1,2,3-oxadiazole perchlorate. Capacity of protonated cation in adopting a cis-I conformation and planar geometry; Role of each perchlorate anion; Interaction of hydrogen bonds in between the protonated cations.

Examines the crystal structure of the organic compound 5-Nitro-2,3-bis(2-pyridyl)quinoxaline. Hydrogen bonding in the compound; Crystallization system of the compound; Arrangements of pyridyl rings in the compound.

Metallic nickel (Ni) is a promising candidate to substitute Pt-based catalysts for hydrogen oxidation reaction (HOR), but huge challenges still exist in precise modulation of the electronic structure to boost the electrocatalytic performances. Herein, we present the use of single-layer Ti3C2Tx MXene to deliberately tailor the electronic structure of Ni nanoparticles via interfacial oxygen bridges, which affords Ni/Ti3C2Tx electrocatalyst with exceptional performances for HOR in an alkaline medium. Remarkably, it shows a high kinetic current of 16.39 mA cmdisk -2 at the overpotential of 50 mV for HOR [78 and 2.7 times higher than that of metallic Ni and Pt/C (20%), respectively], also with good durability and CO antipoisoning ability (1,000 ppm) that are not available for conventional Pt/C (20%) catalyst. The ultrahigh conductivity of single-layer Ti3C2Tx provides fast transmission of electrons for Ni nanoparticles, of which the uniform and small sizes endow them with high-density active sites. Further, the terminated -O/- OH functional groups on Ti3C2Tx directionally capture electrons from Ni nanoparticles via interfacial Ni-O bridges, leading to obvious electronic polarization. This could enhance the Nids- O2p interaction and weaken Nids-H1s interaction of Ni sites in Ni/Ti3C2Txenabling a suitable H-/OH-binding energy and thus enhancing the HOR activity. [ABSTRACT FROM AUTHOR]

In this paper, we are concerned with the Schrödinger–Poisson system {−Δu+u+ϕu=|u|p−2uin Rd,Δϕ=u2in Rd. Due to its relevance in physics, the system has been extensively studied and is quite well understood in the case . In contrast, much less information is available in the planar case which is the focus of the present paper. It has been observed by Cingolani S and Weth T (2016 On the planar Schrödinger–Poisson system Ann. Inst. Henri Poincare33 169–97) that the variational structure of (0.1) differs substantially in the case and leads to a richer structure of the set of solutions. However, the variational approach of Cingolani S and Weth T (2016 On the planar Schrödinger–Poisson system Ann. Inst. Henri Poincare33 169–97) is restricted to the case which excludes some physically relevant exponents. In the present paper, we remove this unpleasant restriction and explore the more complicated underlying functional geometry in the case with a different variational approach. [ABSTRACT FROM AUTHOR]

Co-crystallization of hemimellitic acid (benzene-1,2,3-tricarboxylic acid) dihydrate (H3HMA·2H2O) with 4,4′-bipyridine (4,4′-bpy) affords the 1:1 co-crystal benzene-1,2,3-tricarboxylic acid–4,4′-bipyridine (1/1), H3HMA·4,4′-bpy or C9H6O6·C10H8N2. Strong O—H⋯O hydrogen bonds connect the acid mol­ecules to form a one-dimensional zigzag chain, around which the 4,4′-bpy components are fixed as arms via O—H⋯N inter­actions, resulting in a ladder motif. Through weak C—H⋯O non-covalent forces, the resulting acid layers are extended into a three-dimensional pillar-layered architecture supported by rod-like 4,4′-bpy components. The influence on hydrogen-bonding models is also discussed, with the discovery of an unexpected inter­action motif that does not follow the routine hydrogen-bonded hierarchical rule in the construction of an acid–base co-crystal. [ABSTRACT FROM AUTHOR]

By using different organic acids as additive agents, hydrothermal reactions of AgNO3 with 3,5-bis(2-pyridyl)-4-amino-1,2,4-triazole (2-bpt) lead to formation of two conformational polymorphs of [Ag(2-bpt)](NO3) with bimetallocyclic and 1-D helical coordination patterns. Interconversion between the two supramolecular isomers can be achieved under proper conditions, which will pass through the same intermediate state. [ABSTRACT FROM AUTHOR]

Abstract: Self-penetrating coordination networks have recently been demonstrated as an important family of coordination polymers with new topologies and properties. However, the design and control of self-penetrating systems is still an enthralling challenge. In this review, we present the topological types of self-penetrating coordination networks, mainly with single-connectivity, and summarize their designing and constructing strategy. [Copyright &y& Elsevier]

A series of CdIIcoordination polymers have been designed and hydrothermally synthesized by using a bent dipyridyl tecton 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (3-bpo) and R-isophthalic acids (H2ip-R; R = –H, –CH3, –OCH3, –tBu, –OH, and –NO2), which exhibit diverse 1D and 2D polymeric coordination networks. The results demonstrate that the substituent effect of R-isophthalates does play a decisive role in directing the structural assemblies of this system, in which secondary interactions such as H-bonding and ππ stacking are generally observed to extend the coordination motifs. Notably, the 3-bpo building block shows adaptable conformations (cisoid-I, cisoid-II, and transoid) to facilitate the structural diversity of these complexes. Solid state properties such as thermal stability and fluorescence for these crystalline materials will also be presented. [ABSTRACT FROM AUTHOR]

A series of mixed-ligand coordination complexes have been prepared using diffusion method, by reacting the CoII, NiII, ZnII, AgI, CdII, CuII, or PbIInitrate with tetrabromoterephthalic acid (H2tbta) and 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (4-bpo). These complexes show various 0D, 1D, 2D, and 3D coordination motifs with different geometries of the metal centers, indicating a metal-directed assembly. The synthetic condition will also affect the resulting crystalline products for ZnIIspecies. Crystal structure analysis reveals that secondary interactions such as hydrogen bonding and aromatic stacking will further extend the coordination arrays to diverse supramolecular architectures. All complexes have been characterized by IR, elemental analysis, and powder X-ray diffraction techniques. In addition, the polymeric coordination systems with d10metal centers show solid-state fluorescent emissions at room temperature, which thus may be applied as potential hybrid luminescent materials. [ABSTRACT FROM AUTHOR]

A new coordination polymer, {[Mn(mip)(dps)](dpts)0.5}2n(1) (mip = 5-methylisophthalate) has been solvothermally synthesized by in situgeneration of 4,4′-dipyridylsulfide (dps) and 4,4′-dipyridyltrisulfide (dpts) ligands from a 4,4′-dipyridyldisulfide (dpds) precursor. The coordination framework of 1shows a new (3,5)-connected 3-D net topology with a Schläfli symbol of (42.65.83)(42.6), in which weak antiferromagnetic interactions are observed between the MnIIions. [ABSTRACT FROM AUTHOR]

Chlorine, bromine and iodine substituted derivatives of 5,5′-bisdiazo-dipyrromethane have been synthesized and their crystal structures were studied by X-ray crystallography. In the three structures, the 5,5′-bisdiazo-dipyrromethanes form interlocked dimers through quadruple N–HN hydrogen bonds. The halogenπ synthons also provide a significant contribution to the resulting supramolecular motifs. [ABSTRACT FROM AUTHOR]

A helical water chain, reversibly inlayed in a magnesium imidazole-4,5-dicarboxlylate, was characterized by single-crystal X-ray diffraction, thermogravimetric analysis, as well as temperature-variable Fourier transform infrared spectroscopy and powder X-ray diffraction techniques. [ABSTRACT FROM AUTHOR]

Three kinds of three-dimensional (3D) cadmium(II) pyridine-2,4,6-tricarboxylate ( L) coordination polymers, L-[Cd( L)](NH 2Me 2) ( 1a), R-[Cd( L)](NH 2Me 2) ( 1b), [Cd 3( L) 2(H 2O) 4] ( 2), and [Cd 4( L) 2(OH) 2(H 2O) 3](H 2O) ( 3), have been hydro/solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction. The variations of reaction medium and temperature not only led to an occurrence of spontaneous chiral resolution but also afforded two achrial molecular building block structures. Complexes 1aand 1bcrystallize in trigonal P3 121 and P3 221 space groups with homochiral left- and right-handed double-helical strand arrays, while 2and 3self-assemble into two kinds of achiral coordination polymers with molecular building block structures. Complexes 2and 3remain intact after removal of the coordinated water molecules, which indicates that their dehydrated frameworks possess guest-free metal coordination sites. Complexes 1– 3also display strong fluorescent emissions at 638, 594, and 604 nm in the solid state. [ABSTRACT FROM AUTHOR]

Six new metal-organic coordination networks based on linking unit 2,5-bis(4-pyridyl)-l,3,4-thiadiazole (L¹) or 2,5bis(3-pyridyl)-l,3,4-oxadiazole (L³) and inorganic CuΙΙ CdΙΙ, and CoΙΙ salts have been prepared and structurally characterized by single-crystal X-ray analysis. Using L¹ to react with three different CuΙΙsalts, Cu(OAc)2·H2O, Cu(NO3)2·3H2O, and CuSO4·5H20, respectively, two different one-dimensional (l-D) coordination polymers, {[Cu2L¹(μOAc)4](CHCI3)2}n (1) [triclinic, space group P1macr;, a = 7.416(3) Å, b = 8.207(3) Å, c = 14.137(5) Å, α = 100.333(7)°, β = 105.013(6)°, γ = 94.547(6)°, Z = 1] and {[CuL¹(NO3)2](CHCI3)0.5}n (2)[monoclinic, space group C2/c, a = 28.070(8) Å, b = 9.289(3) Å, c= 15.235(4) Å, β = 113.537(5)°, Z = 8], and a chiral 3-D open framework, {[CuL¹(H2O)(SO4)](H20)2}n (3)[orthorhombic, space group P212121, a = 5.509(2), Å b = 10.545(4) Å, c = 29.399(11) Å, Z = 4], were obtained. Reaction of L¹ and Cd(ClO4)2·6H2O or Co(ClO4)2·6H2O, in the presence of NH4SCN, yielded another 3-D open framework, {[CdL¹(NCS)2](CH3OH) 1,5}n (4) [monoclinic, space group C2/c, a = 28.408(10) Å, b = 9.997(5) Å, c = 7.358(4) Å, β = 99.013(8)°, Z= 4], or a 2-D network, {[Co(L¹)2 (NCS) 2](H2O)2.5}n (5) [orthorhombic, space group Pnna, a = 22.210(5) Å, b = 12.899(3) Å, c = 20.232(4) Å, Z = 4]. When L¹ was replaced by L³ to react with Co(CIO4)2·6H20 and NH4SCN, another 2-D coordination polymer, [Co(L³)2(NCS)2]n (6) [monoclinic, space group P21/c, a = 8.120(3) Å, b = 9.829(4) Å, c = 17.453(6) Å, β = 103.307(6)°, Z = 2], was constructed. These results indicate that the nature of the ligands, metal centers, or counteranions plays the critical role in construction of these novel coordination polymers. The interesting porous natures of two 3-D open frameworks 3 and 4 were investigated by TGA and XPRD techniques, and the magnetic properties of the CuΙΙ and CoΙΙ complexes were studied by variable-temperature magnetic susceptibility and magnetization measurements. [ABSTRACT FROM AUTHOR]

Evaluates the properties of copper complexes formed by the hydrolysis of 3,6-Di-2-pyridyl-1,2,4,5-tetrazine. Crystal values of the copper complexes; Function of oxodiazole complex in mononuclear and polymer complexes; Mechanism of the metal assisted hydrolysis.

Examines the features of metal complexes with a flexible bis(sulfinyl). Propensity to form multidimensional coordination polymers with transition metals and rare earth elements; Preference for O-binding in hard acid metal complexes; Ability of the ligands to form diverse extended networks.

Examines the crystallography and photophysical and electrochemical properties of dinuclear or chain polymeric silver(I) complexes with polypyridyl bridging ligands by cyclic voltammetry and emission and electronic absorption spectra. Bond lengths and angles; Thermal ellipsoid at 30% probability.