Selective oxidation of ß-keto ester modulated by the d-band centers in D-A conjugated microporous metallaphotoredox catalysts containing M-salen (MZn, Cu and Co) and triazine monomers.

Photocatalytic selective oxidation plays an important role in developing green chemistry. However, it is challenging to design an efficient photocatalyst for controlling the selectivity of photocatalytic oxidation reaction and exploring its detailed mechanism. Here, we synthesized three conjugated microporous polymers (CMPs) with D-A structures, named M-SATE-CMPs (MZn, Cu and Co), with different d-band centers based on different metal centers, resulting in the discrepancy in adsorption and activation capacities for the reactants, which produces the selectivity of ß-keto esters being catalyzed into α-hydroperoxide ß-keto esters (ROOH) or to α-hydroxyl ß-keto esters (ROH). Density functional theory (DFT) calculations also demonstrate that the adsorption and activation capacities of the metal active centers in M-SATE-CMPs (MZn, Cu and Co) for ROOH are the key factors to influence the photocatalytic selective oxidation of ß-keto ester. This study provides a promising strategy for designing a metallaphotoredox catalyst whose photocatalytic selectivity depends on the d-band center of metal site in the catalyst.

A linker conformation induced metal-organic framework with high stability and efficient upgrading of natural gas.

Natural gas plays an important role in daily life and the petrochemical industry, but there are often large amounts of impurities which prevent the full use of methane in natural gas. Developing excellent adsorbents to purify CH4 from multi-component mixtures is crucial, but also faces great challenges. Here, by utilizing a ligand conformation preorganization strategy, we employ a flexible nonplanar hexacarboxylate ligand with C2 symmetry to successfully construct a robust microporous metal-organic framework {[Cu3(bmipia)(H2O)3]·(DMF)(CH3CN)2}n (GNU-1, bmipia = 5-[N,N-bis(5-methylisophthalic acid)amion] isophthalate) with an unprecedented topology. More importantly, the obtained GNU-1 not only exhibits good stability in acid-base and water environments, but also shows potential utility as an adsorbent for efficient separation and purification of natural gas under ambient conditions. The adsorption isotherms of GNU-1a (activated GNU-1) exhibit strong binding affinities for C2H6 and C3H8, a remarkable uptakes of C3H8 (6.64 mmol g-1) and C2H6 (4.6 mmol g-1) and an excellent selectivity of 330.1 and 17.5 for C3H8/CH4 and C2H6/CH4 mixtures, respectively, at 298 K and 1 bar. The breakthrough experiments demonstrate that the ternary CH4/C2H6/C3H8 mixtures are completely separated using a fixed-bed separator packed with GNU-1a at ambient temperature and also show great potential for recovering the C2H6 and C3H8 contents from natural gas. Finally, Grand Canonical Monte Carlo simulations are adopted to ascertain potential gas adsorption mechanisms. This work proves the feasibility of optimizing the structure and pore size of MOF materials by regulating the conformation of ligands for application in the field of light hydrocarbon adsorption/separation.

Fabrication of a lead-free ternary ceramic system for high energy storage applications in dielectric capacitors.

The importance of electroceramics is well-recognized in applications of high energy storage density of dielectric ceramic capacitors. Despite the excellent properties, lead-free alternatives are highly desirous owing to their environmental friendliness for energy storage applications. Herein, we provide a facile synthesis of lead-free ferroelectric ceramic perovskite material demonstrating enhanced energy storage density. The ceramic material with a series of composition (1-z) (0.94Na0.5Bi0.5TiO3-0.06BaTiO3)-zNd0.33NbO3, denoted as NBT-BT-zNN, where, z = 0.00, 0.02, 0.04, 0.06, and 0.08 are synthesized by the conventional solid-state mix oxide route. Microphases, microstructures, and energy storage characteristics of the as-synthesized ceramic compositions were determined by advanced ceramic techniques. Powder X-ray diffraction analysis reveals pure single perovskite phases for z = 0 and 0.02, and secondary phases of Bi2Ti2O7 appeared for z = 0.04 and 0.08. Furthermore, scanning electron microscopy analysis demonstrates packed-shaped microstructures with a reduced grain size for these ceramic compositions. The coercive field (Ec) and remnant polarization (Pr) deduced from polarization vs. electric field hysteresis loops determined using an LCR meter demonstrate decreasing trends with the increasing z content for each composition. Consequently, the maximum energy storage density of 3.2 J/cm3, the recoverable stored energy of 2.01 J/cm3, and the efficiency of 62.5% were obtained for the z content of 2 mol% at an applied electric field of 250 kV/cm. This work demonstrates important development in ceramic perovskite for high power energy storage density and efficiency in dielectric capacitors in high-temperature environments. The aforementioned method makes it feasible to modify a binary ceramic composition into a ternary system with highly enhanced energy storage characteristics by incorporating rare earth metals with transition metal oxides in appropriate proportions.

A Nanocluster [Ag307Cl62(SPhtBu)110]: Chloride Intercalation, Specific Electronic State, and Superstability.

The controlling synthesis of novel nanoclusters of noble metals (Au, Ag) and the determination of their atomically precise structures provide opportunities for investigating their specific properties and applications. Here we report a novel silver nanocluster [Ag307Cl62(SPhtBu)110] (Ag307) whose structure is determined by X-ray single crystal diffraction. The structure analysis shows that nanocluster Ag307 contains a Ag167 core, a surface shell of [Ag140Cl2S110], and a Cl60 intermediate layer located between Ag167 and [Ag140Cl2S110]. It is a first example that such many chlorides are intercalated into a Ag nanocluster. Chlorides are released in situ from solvent CHCl3. Nanocluster Ag307 exhibits superstability. Differential pulse voltammetry experiment reveals that Ag307 has continuous charging/discharging behavior with a capacitance value of 1.39 aF, while the Ag307 has a surface plasmonic feature. These characteristics show that Ag307 is of metallic behavior. However, its electron paramagnetic resonance (EPR) spectra display a spin magnetic behavior which could be originated from the unpassivated dangling bonds of surface atoms. The direct capture of EPR signals can be attributed to the Cl- intercalating layer which partly suppresses the electronic interactions between core and surface atoms, resulting in the relatively independent electronic states for core and surface atoms.

Synthesis, structural characterization and antitumor activity of six rare earth metal complexes with 8-hydroxyquinoline derivatives.

The rare earth metal Gd(III), Yb(III), Lu(III), Eu(III), Tb(III) and Ho(III) complexes 1-6 with 2-((2-(pyridin-2-yl)hydrazono)methyl)quinolin-8-ol (H-L) as ligands were synthesized. The in vitro cytotoxicity assay indicated that the cytotoxicity of 1 was equivalent to cisplatin and higher than that of H-L and other complexes towards T24 tumor cells. The mechanism study indicated that 1 caused significant up-regulation of the proteins p27, p21 and p53 in T24 cells and cell cycle arrest in G2 phase. In addition, 1 induced effective T24 cells apoptosis via mitochondrial dysfunction pathway, which was indicated by changes in mitochondrial membrane potential (Δψ), reactive oxygen species (ROS), intracellular Ca2+ and the mitochondria-related proteins (including cytochrome C (Cyt C), B-cell lymphoma-2 (Bcl-2), Bcl-2-associated x (Bax) and apoptotic protease activating factor-1 (Apaf-1)). Moreover, 1 could activate caspase-3/8/9 in T24 cells. Therefore, complex 1 is a promising and potent anticancer drug candidate.

A Discrete Tetrahedral Indium Cage as an Efficient Heterogeneous Catalyst for the Fixation of CO2 and the Strecker Reaction of Ketones.

A discrete tetrahedral indium cage, {[In12(µ3-OH)4(HCO2)24(tcma)4]} (In12-GL), was synthesized solvothermally by the reaction of indium nitrate with the tripodal tricarboxylic acid ligand N,N,N-tris{(2'-carboxy[1,1'-biphenyl]-4-yl)methyl}methylammonium chloride ([H3tcma]+Cl). This cage consists of four trimeric units [In3(µ3-OH)(µ2-CO2)3(µ2-HCO2)3] and four [tcma]2- ligands, which all perform as 3-connection nodes to bridge each other, resulting in a tetrahedral cage structure. The trimeric unit [In3(µ3-OH)(µ2-CO2)3(µ2-HCO2)3] is observed for the first time in the family of In-based metal-organic structures and can be considered as an evolution of a 6-connected [In3(µ3-O)(µ2-CO2)6] unit. Each In3+ is terminally coordinated by a µ1-HCO2 group. This cage contains potential Lewis acidic/basic active sites endowed by In3+ ions as Lewis acidic sites and the uncoordinated oxygen atoms of µ1-HCO2 moieties as Lewis basic sites and was explored as an effective heterogeneous catalyst in the cycloaddition of CO2 with epoxides and the Strecker reaction for amino nitriles. These catalytic reactions were deduced to happen on the surface of the In12-GL cage.

[Ag15(N-triphos)4(Cl4)](NO3)3: a stable Ag-P superatom with eight electrons (N-triphos = tris((diphenylphosphino)methyl)amine).

A first and stable Ag-P superatom nanocluster [Ag15(N-triphos)4(Cl4)](NO3)3 (1) has been successfully synthesized and characterized. X-ray analysis shows that this Ag15 cluster has a hexacapped body-centered cubic (bcc) framework which is consolidated by four tripodal N-triphos ligands. The identity of 1 is confirmed by high resolution ESI-MS. Cluster 1 has an electronic and geometric shell closure structure with 8 free electrons, matching the stability idea of superatom theory for a nanocluster. DFT calculation of this Ag15 cluster reveals the superatom feature with a 1S21P6 configuration. The chelation of multidentate phosphines enhances the stability of this Ag15 cluster. The AgAg distances between the centered and the vertical Ag atoms of this bcc (Ag@Ag8) are in the range of 2.57-2.71 Å, and the distances between the face-capped and the vertical silver atoms are in the range of 2.84-2.92 Å, showing strong AgAg interactions within this cluster core. This superatom complex exhibits a relatively high thermal and photolytic stability.

Rare double spin canting antiferromagnetic behaviours in a [Co24] cluster.

A fish-basket-shaped [Co24] cluster, [Co24(µ3-O)4(ampc)4(µ3-OH)4(µ2-OH)4(NO3)5(HCO2)22(H2O)10]·[(HCO2)·2(CH3OH)·x(H2O)], was woven by bridging oxygen atoms from O(2-), OH(-), NO3(-) and HCO2(-) groups, and stabilized terminally by a semi-rigid organic ligand 4',4'-[(dimethylamino)dimethylene]-bis[(1,1'-biphenyl)-2-carboxylate] (ampc(-)). Magnetic analyses indicate that the [Co24] cluster exhibits two types of spin canting orders, spin flop and a small hysteresis with a coercive field of ca. 661 Oe and a remanent magnetization of 0.466 Nß.

Aggregation of the metallocycles {Cu8} and {Cu20} using [Cu(bp)] units (H2bp = bis(2-hydroxybenzyl)amine): structures and magnetic properties.

Two metallocycles, {Cu8(bp)4(OH)4(H2O)4(ClO4)4} (1) and {Cu20(bp)20} (2), were afforded by the reactions of the semi-flexible tridentate ligand bis(2-hydroxybenzyl)amine (H2bp) with Cu(ClO4)2·6H2O and Cu(OAc)2·H2O. Complex 1 has a saddle-shaped cyclic structure and complex 2 has a nanosized wheel-shaped structure. The two compounds consist of [Cu(bp)] units.

Nanospheric [M20(OH)12(maleate)12(Me2NH)12]4+ clusters (M = Co, Ni) with O(h) symmetry.

Nanospheric hydroxo-bridged clusters of [M(20)(OH)(12)(maleate)(12)(Me(2)NH)(12)](BF(4))(3)(OH)·nH(2)O (M = Co (1), Ni (2)) with O(h) symmetry were afforded under hydrothermal condition with Co(BF(4))(2)·6H(2)O/Ni(BF(4))(2)·6H(2)O and fumaric acid in a DMF/EtOH mixed solvent. They are characterized by elemental analysis, IR, and X-ray diffraction. X-ray single crystal diffraction analyses show that these two complexes are isostructural containing an ideally cubic M(8) core in that each two M atoms are doubly bridged at the edges by one OH(-) and one maleate, while these OH(-) and maleate groups are coordinated further by exterior identical 12 M atoms which construct a perfect M(12) icosahedron to encapsulate the cubic core. To our knowledge, such large clusters with O(h) symmetry are seldom. The variable-temperature magnetic susceptibility studies reveal that these two isostructures exhibit antiferromagnetic interactions.

Synthesis, structural characterization and luminescent properties of a series of Cu(I) complexes based on polyphosphine ligands.

A series of Cu(I) complexes with a [Cu(NN)(PP)](+) moiety, [Cu(phen)(pba)](BF(4)) (1a), [Cu(2)(phen)(2)(pbaa)](BF(4))(2) (2a), [Cu(2)(phen)(2)(pnaa)](BF(4))(2) (3a), [Cu(2)(phen)(2)(pbbaa)](BF(4))(2) (4a), [Cu(dmp)(pba)](BF(4)) (1b), [Cu(2)(dmp)(2)(pbaa)](BF(4))(2) (2b), [Cu(2)(dmp)(2)(pnaa)](BF(4))(2) (3b) and [Cu(2)(dmp)(2)(pbbaa)](BF(4))(2) (4b) (phen = 1,10-phenanthroline, dmp = 2,9-dimethyl-1,10-phenanthroline, pba = N,N-bis((diphenylphosphino)methyl)benzenamine, pbaa = N,N,N',N'-tetrakis((diphenylphosphino)methyl)benzene-1,4-diamine, pnaa = N,N,N',N'-tetrakis((diphenylphosphino)methyl)naphthalene-1,5-diamine and pbbaa = N,N,N',N'-tetrakis((diphenylphosphino)methyl)biphenyl-4,4'-diamine), were rationally designed and synthesized. These complexes were characterized by (1)H and (31)P NMR, electrospray mass spectrometry, elemental analysis and X-ray crystal structure analysis. Introduction of different central arene spacers (phenyl, naphthyl, biphenyl) into ligands, resulting in the size variation of these complexes, aims to tune the photophysical properties of the complexes. Each Cu(I) ion in these complexes adopts a distorted tetrahedral geometry constructed by the chelating diimine and phosphine groups. Intermolecular C-H···π and/or π···π interactions are involved in the solid states. The dmp-containing complex exhibits better emission relative to the corresponding phen complex due to the steric encumbrance of bulky alkyl groups. Furthermore, for complexes with identical diimine but different phosphine ligands, the tendency of increased emission lifetime as well as blue-shifted emission in the solid state follows with the decrease in size of complexes. Intermolecular C-H···π interactions have an influence on the final solid state photophysical properties through vibrationally relaxed non-radiative energy transfer in the excited state. Smaller-sized complexes show better photophysical properties due to less vibrationally relaxed behavior related to flexible C-H···π bonds. Nevertheless, the tendency for increased quantum yield and emission lifetime, as well as blue-shifted emission in dilute solution goes with the increase in size of complexes. The central arene ring (phenyl, naphthyl or biphenyl) has an influence on the final photophysical properties. The larger the π-conjugated extension of central arene ring is, the better the photophysical properties of complex are. The rigid and large-sized complex 3b, with a high quantum yield and long lifetime, is the best luminophore among these complexes.

A double-layered zinc(II) coordination polymer with the ligand 3,5-bis(carboxylatomethoxy)benzoate.

In the title compound, poly[hexaaquabis[mu(4)-3,5-bis(carboxylatomethoxy)benzoato]trizinc(II)], [Zn(3)(C(11)H(7)O(8))(2)(H(2)O)(6)](n), there are two crystallographically distinct Zn(II) cations which are bridged by polycarboxylate ligands in a mu(4)-bridging mode. A pair of ligands bridges adjacent Zn atoms to give centrosymmetric dimetal building blocks which act as four-connected nodes to be further interlinked into a two-dimensional double-layered framework with (4,4) topology. Other Zn atoms, lying on inversion centres, occupy the cavities of this topological structure. This submission shows a versatile polycarboxylate ligand with rigid and flexible functional groups, the co-operation and complementarity of which would meet the coordination requirements of a variety of topological structures.

{µ-trans-N,N'-Bis[(diphenyl-phosphan-yl)meth-yl]benzene-1,4-diamine-κP:P'}bis-{(acetonitrile-κN)[dipyrido[3,2-a:2',3'-c]phenazine-κN,N]copper(I)} bis-(tetra-fluoridoborate).

In the centrosymmetric dinuclear title compound, [Cu(2)(C(2)H(3)N)(2)(C(18)H(10)N(4))(2)(C(32)H(30)N(2)P(2))](BF(4))(2), the Cu(I) centre is coordinated by two N atoms from a dipyridophenazine ligand, one P atom from an N,N'-bis-[(diphenyl-phosphan-yl)meth-yl]benzene-1,4-diamine (bpbda) ligand, and one N atom from an acetonitrile mol-ecule in a distorted tetra-hedral geometry. The bpbda ligand, lying on an inversion center, bridges two Cu(I) centres into a Z-shaped complex. Intra-molecular π-π inter-actions between the dipyridophenazine ligand and the benzene ring of the bpbda ligand are observed [centroid-centroid distance = 3.459 (3) Å]. The crystal structure also involves inter-molecular π-π inter-actions between the dipyridophenazine ligands [centroid-centroid distance = 3.506 (3) Å], which lead to a one-dimensional supra-molecular structure.

Bis[4-(2-hydroxy-benzyl-ideneamino)benzoato-κO]tetrakis-(methanol-κO)manganese(II).

In the title mononuclear complex, [Mn(C(14)H(10)NO(3))(2)(CH(3)OH)(4)], the Mn(II) atom, lying on an inversion centre, exhibits a distorted octa-hedral geometry, defined by two O atoms from two monodentate ligands and four O atoms from four methanol mol-ecules. The crystal structure involves intra-molecular O-H⋯N and O-H⋯O and inter-molecular O-H⋯O hydrogen bonds.

[µ-N,N'-Bis(diphenyl-phosphinometh-yl)benzene-1,4-diamine-κP:P']bis-[(2,2'-bipyridine-κN,N')silver(I)] bis-(per-chlorate) acetone disolvate.

The title complex, [Ag(2)(C(10)H(8)N(2))(2)(C(32)H(30)N(2)P(2))](ClO(4))(2)·2CH(3)COCH(3), is a centrosymmetric dimer with pairs of Ag(I) atoms bridged by N,N'-bis-(diphenyl-phosphinometh-yl)ben-zene-1,4-diamine ligands. In addition, each Ag(I) atom is coordin-ated by one chelating 2,2'-bipyridine ligand, giving a distorted trigonal coordination environment.

[µ-N,N,N',N'-Tetra-kis(diphenyl-phosphino-meth-yl)benzene-1,4-diamine-κP,P':P'',P''']bis-[bis-(nitrato-κO)palladium(II)].

The asymmetric unit of the title complex, [Pd(2)(NO(3))(4)(C(58)H(52)N(2)P(4))], contains one half-mol-ecule, in which the central benzene ring is located on a crystallographic centre of inversion. The Pd atom has a distorted square-planar coordination consisting of two P and two O atoms. In the crystal structure, inter-molecular C-H⋯O inter-actions link the mol-ecules into chains, and π-π contacts between the phenyl rings [centroid-centroid distance = 3.928 (3) Å] may further stabilize the structure.

A coordination polymer of CdCl2 with the novel zwitterionic dicarboxylate ligand 2,2'-(2-methylbenzimidazolium-1,3-diyl)diacetate (pda).

The title compound, poly[chlorido[mu(4)-2,2'-(2-methylbenzimidazolium-1,3-diyl)diacetato]cadmium(II)], [Cd(C(12)H(11)N(2)O(4))Cl](n), is an undulating two-dimensional polymer consisting of a paddlewheel Cd(2)(CO(2))(4) cluster which lies on an inversion centre. These paddlewheel clusters act as four-connected square building units interlinked via bridging zwitterionic dicarboxylate ligands into a corrugated layer which is consolidated by pi-pi interactions between benzene rings of benzimidazole groups. Neighbouring layers are further assembled via interlayer pi-pi interactions into a three-dimensional supramolecular structure. The key feature of this study is the synthesis of a paddlewheel-based polymer constructed with a novel multifunctional zwitterionic dicarboxylate ligand.

catena-poly[[[pyridinecopper(II)]bis[mu3-4-(2-oxidobenzylideneamino)benzoato]] dimethylformamide disolvate], a polymer composed of dimeric dicopper building units.

The title compound, {[Cu(C(14)H(9)NO(3))(C(5)H(5)N)].C(3)H(7)NO}n or {[Cu(2)L(2)(py)(2)].2DMF}n [py is pyridine, L is 4-(salicylideneamino)benzoate and DMF is dimethylformamide], is composed of dimeric dicopper [CuL(py)]2 building units, which are interlinked into a one-dimensional chain through the formation of Cu-O(COO) bonds. The dimeric unit is centrosymmetric, containing two Cu(II) atoms linked by bridging phenolate O atoms into a Cu(2)O(2) plane with a chelating Cu-O bond length of 1.927 (2) A and a bridging Cu-O bond length of 2.440 (2) A. Interchain C-H...O and pi-pi stacking interactions are responsible for an extensive three-dimensional structure in which the resulting channels are filled by DMF solvent molecules.