The Difference Se Makes: A Bio-Inspired Dppf-Supported Nickel Selenolate Complex Boosts Dihydrogen Evolution with High Oxygen Tolerance.

Inspired by the metal active sites of [NiFeSe]-hydrogenases, a dppf-supported nickel(II) selenolate complex (dppf=1,1'-bis(diphenylphosphino)ferrocene) shows high catalytic activity for electrochemical proton reduction with a remarkable enzyme-like H2 evolution turnover frequency (TOF) of 7838 s-1 under an Ar atmosphere, which markedly surpasses the activity of a dppf-supported nickel(II) thiolate analogue with a low TOF of 600 s-1 . A combined study of electrochemical experiments and DFT calculations shed light on the catalytic process, suggesting that selenium atom as a bio-inspired proton relay plays a key role in proton exchange and enhancing catalytic activity of H2 production. For the first time, this type of Ni selenolate-containing electrocatalyst displays a high degree of O2 and H2 tolerance. Our results should encourage the development of the design of highly efficient oxygen-tolerant Ni selenolate molecular catalysts.

Silver-Sulfur Hybrid Supertetrahedral Clusters: The Hitherto Missing Members in the Metal-Chalcogenide Tetrahedral Clusters.

The synthesis of Group 11 metal chalcogenide supertetrahedral clusters (SCs) still remains a great challenge mainly due to the high tendency of metal aggregation through metallophilicity and global charge balance. Demonstrated herein are the preparation, crystallographic characterization, and optical properties of two stable silver-sulfur SCs through ligand-control; one as a discrete zero-dimensional (0D) V3,4-type cluster and the other as a one-dimensional (1D) zigzag chain extended by alternating V3,2-type clusters. The notation Vn,m (where n is the number of metal layers, and m is the number of vacant corners) is used to describe a new series of vacant-corner SCs, which can be derived from the regular Tn clusters. The existence of vacant-corner-type SCs may be ascribed to the low valence and tri-coordinated environment of silver ions. These are the first representatives of structurally determined silver-sulfur tetrahedral clusters thus far. This work enriches the coinage-metal chalcogenide tetrahedral cluster portfolio, discovers vacant-corner SCs present in silver-sulfur hybrid tetrahedral clusters, and provides effective means for further development of Group 11 coinage-metal chalcogenide SCs.

The relationship between the boron dipyrromethene (BODIPY) structure and the effectiveness of homogeneous and heterogeneous solar hydrogen-generating systems as well as DSSCs.

A series of boron dipyrromethene (BODIPY) dyes (B1­B5) having H atoms at 2,6-positions or heavy-atom I at 2-/2,6-positions, and an ortho- or a para-COOH substituted phenyl moiety at the 8-position on the BODIPY core were synthesized and characterized. These organic dyes were applied for investigating the relationship between the BODIPY structure and the effectiveness of homogeneous and heterogeneous visible-light-driven hydrogen production as well as dye-sensitized solar cells (DSSCs). For the homogeneous photocatalytic hydrogen production systems with a cobaloxime catalyst, the efficiency of hydrogen production could be tuned by substituting with heavy atoms and varying carboxyl group orientations of BODIPYs. As a result, B5 containing two I atoms and an ortho-COOH anchoring group was the most active one (TONs = 197). The activity of hydrogen generation followed the order B5 > B3 > B2 > B1 = B4 = 0. An interesting "ortho-position effect" was observed in the present homogeneous systems, i.e., substitution groups were located at the ortho-position and higher hydrogen production activities were obtained. For the heterogeneous hydrogen production systems with a platinized TiO2 catalyst, the effectiveness of hydrogen evolution was highly influenced by the intersystem crossing efficiency, molar absorptivity and positions of the anchoring group of dyes. Thus, B3 having two core iodine atoms and a para-COOH group with TONs of 70 excelled other BODIPYs and the TONs of hydrogen generation showed the trend of B3 > B5 > B2 > B1 = B4 = 0. The results demonstrate that the present photocatalytic H2 production proceeds with higher efficiency and stability in the homogeneity than in the heterogeneity. In the case of DSSCs, the overall cell performance of BODIPY chromophores was highly dependent on both the absence or the presence of iodine atoms on the BODIPY core and ­COOH anchoring positions. The B1­TiO2 system showed the best cell performance, because the most effective surface binding mode is allowed with this structure. This is also in contrast with the case of dye-sensitized solar H2 generation, in which B3 was the most efficient chromophore. The differences between dye-sensitized hydrogen-generating systems and DSSCs may be due to rates of electron transfer and the dye aggregation tendency.

Noble-metal-free BODIPY-cobaloxime photocatalysts for visible-light-driven hydrogen production.

In this study a series of supramolecular BODIPY-cobaloxime systems Co-Bn (n = 1-4): [{Co(dmgH)2Cl}{4,4-difluoro-8-(4-pyridyl)-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene}] (Co-B1), [{Co(dmgH)2Cl}{4,4-difluoro-8-(4-pyridyl)-1,3,5,7-tetramethyl-2,6-diiodo-4-bora-3a,4a-diaza-s-indacene}] (Co-B2), [{Co(dmgH)2Cl}{4,4-difluoro-8-(3-pyridyl)-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene}] (Co-B3), and [{Co(dmgH)2Cl}{4,4-difluoro-8-(3-pyridyl)-1,3,5,7-tetramethyl-2,6-diiodo-4-bora-3a,4a-diaza-s-indacene}] (Co-B4) (BODIPY = boron dipyrromethene, dmgH = dimethylglyoxime) have been synthesized by replacing one axial chlorine of cobaloxime moieties with the pyridine residues of BODIPYs, and structurally characterized. Absorption spectra show that the optical properties of the BODIPY-cobaloximes are essentially the sum of their constituent components, indicating weak interactions between the cobaloxime units and BODIPY chromophores in the ground state. If any, electronic communications may take place through the intramolecular electron transfer across their orthogonal structures. The possibility of intramolecular electron transfer is further supported by the results of the density functional theory (DFT) calculations at UB3LYP/LANL2DZ levels on Co-B2˙(-) and Co-B4˙(-), which show that the highest occupied molecular orbitals (HOMOs) possess predominantly BODIPY character, while the lowest unoccupied molecular orbitals (LUMOs) are located on the cobalt centers. The HOMO → LUMO transition is an electron-transfer process (BODIPY˙(-) radical anions → cobaloxime fragments). In view of the possible occurrence of electron transfer, these noble-metal-free BODIPY-cobaloximes are studied as single-component homogeneous photocatalysts for H2 generation in aqueous media. Under optimized conditions, the 2,6-diiodo BODIPY-sensitized cobaloxime Co-B4 that contains a meta-pyridyl at the 8-position of BODIPY presents excellent H2 photoproduction catalytic activity with a turnover number (TON) of 85, which is comparable to that of its analogue Co-B2 that has a para-pyridyl attached onto 2,6-diiodo BODIPY (TON = 82); however, both of the noniodinated BODIPY-sensitizer cobaloximes (Co-B1, Co-B3) exhibit a complete lack of activity under the same experimental conditions. These results show that the presence of heavy atoms in the core of BODIPY is essential for the catalytic process and reductive quenching pathways (namely, the intramolecular electron transfers from BODIPY˙(-) species to the cobalt centers) for these photocatalytically active systems of Co-Bn (n = 2 and 4) are thermodynamically feasible for the hydrogen-evolving reaction.

Carbon-reinforced Ni3S2/Ti3C2Tx MXene composite as an anode for superior-performance lithium-ion capacitors.

Lithium ion capacitors (LICs) are a new generation of energy storage devices that combine the super energy storage capability of lithium ion batteries with the satisfactory power density of supercapacitors. The development of high-performance LICs still faces great challenges due to the unbalanced reaction kinetics at the anode and cathode. Therefore, it is an inevitable need to enhance the electron/ion transfer capability of the anode materials. In this paper, to obtain a superior-rate and high-capacity Ni3S2-based anode, highly conductive Ti3C2Tx MXene sheets were introduced to sever as the carrier of Ni3S2 nanoparticles and simultaneously an amorphous carbon layer which coats onto the surface of Ni3S2 nanoparticles was in-situ generated by the carbonization of dopamine reactant. The as-synthesized Ni3S2/Ti3C2Tx/C composite exhibits a high specific surface area (112.6 m2/g) because of the addition of Ti3C2Tx that can reduce the aggregation of Ni3S2 nanoparticles and the in-situ generated amorphous carbon layer that can suppress the growth of Ni3S2 nanoparticles. The Ni3S2/Ti3C2Tx/C anode possesses a remarkable reversible discharge specific capacity (626.0 mAh/g under 0.2 A/g current density), which increases to 1150.8 mAh/g after 400-cycle charge/discharge measurement at the same measurement condition indicating eminent cyclability, along with superior rate capability. To construct a superior-performance LIC device, a sterculiae lychnophorae derived porous carbon (SLPC) cathode with an average discharge specific capacity of 73.4 mAh/g@0.1A/g was prepared. The Ni3S2/Ti3C2Tx/C//SLPC LIC device with optimal cathode/anode mass ratio has a satisfactory energy density ranging from 32.8 to 119.1 Wh kg-1 at the corresponding power density of 8799.4 to 157.5 W kg-1, together with a prominent capacity retention (95.5 %@1 A/g after 10,000 cycles).

Amorphous Co-Mo-S nanospheres fabricated via room-temperature vulcanization for asymmetric supercapacitors.

Ternary metal sulfides employed in supercapacitors exhibit better electrochemical performances than their counterpart oxides due to their superior conductivity. However, the insertion/extraction of electrolyte ions can lead to a significant volume change in electrode materials, which can result in poor cycling stability. Herein, novel amorphous Co-Mo-S nanospheres were fabricated through a facile room-temperature vulcanization method. It involves the conversion of crystalline CoMoO4 by reacting it with Na2S at room temperature. In addition to the conversion of the crystalline state into an amorphous structure with more grain boundaries, which is beneficial for the transport of electron/ion and can accommodate the volume change generated by the insertion/extraction of electrolyte ions, the production of more pores led to an increased specific surface area. The electrochemical results indicate that the as-prepared amorphous Co-Mo-S nanospheres had a specific capacitance of up to 2049.7F/g@1 A/g together with good rate capability. The amorphous Co-Mo-S nanospheres can be used as the cathode of supercapacitors and assembled with an activated carbon anode into an asymmetric supercapacitor possessing a satisfactory energy density of 47.6 Wh kg-1@1012.9 W kg-1. One of the prominent features exhibited by this asymmetric device is its remarkable cyclic stability, with a capacitance retention of 107% after 10,000 cycles.

Poly[diaqua-tris(µ(4)-isophthalato)dilanthanum(III)].

In the title coordination polymer, [La(2)(C(8)H(4)O(4))(3)(H(2)O)(2)](n), there are two independent La(III) atoms which are coordinated differently in slightly distorted penta-gonal-bipyramidal and slightly disorted bicapped trigonal-prismatic environments. The La(III) ions are bridged by µ(4)-isophthalate ligands, forming two-dimensional layers. In the crystal structure, these layers are connected by inter-molecular O-H⋯O hydrogen bonds into a three-dimensional network.

Poly[[diaqua-bis-(µ(3)-isonicotinato-κN:O:O')bis-(µ(2)-isonicotinato-κN:O)gadolinium(III)disiliver(I)] nitrate monohydrate].

In the title compound, {[Ag(2)Gd(C(6)H(4)NO(2))(4)(H(2)O)(2)]NO(3)·H(2)O}(n), the Gd(III) ion is coordinated by eight O atoms from six isonicotinate ligands and two water mol-ecules in a distorted square anti-prismatic geometry. Two Ag(I) ions are each bonded to two N atoms from two isonicotinate ligands in a linear or bow-like fashion [N-Ag-N angles = 178.6 (2) and 147.1 (2)°]. These metal ions are connected by the isonicotin-ate ligands into a layer parallel to (010). O-H⋯O hydrogen bonds donated by the coordinated and uncoordinated water mol-ecules and intra-layer π-π stacking inter-actions between the pyridine rings [centroid-centroid distances = 3.551 (4) and 3.555 (4) Å] are observed. The layers inter-act with each other by inter-layer Ag⋯O(aqua) contacts [2.731 (4) Å] and π-π stacking inter-actions between the pyridine rings [centroid-centroid distances = 3.466 (3) and 3.516 (3) Å], resulting in the formation of a three-dimensional supra-molecular structure.

Bis(µ-N,N-dimethyl-dithio-carbamato-κS,S':S)bis-[(N,N-dimethyl-dithio-carbamato-κS,S')copper(II)].

In the centrosymmetric dimeric title compound, [Cu(2)(C(3)H(6)NS(2))(4)], the Cu(II) atom is five-coordinate in a square-pyramidal environment. The basal coordination positions are occupied by four S atoms from two dimethyl-dithio-carbamate ligands and the apical coordination position is occupied by an S atom also bonded to the other Cu atom.

(N,N-Diethyl-dithio-carbamato-κS,S')iodido(1,10-phenanthroline-κN,N')copper(II).

The copper(II) atom in the title compound, [Cu(C(5)H(10)NS(2))I(C(12)H(8)N(2))], is chelated by the N-heterocycle and the dithio-carbamate anion in a slightly distorted tetragonal coordination. The tetragonal-pyramidal coorination is completed by the iodine atom in the apical position. One ethyl group is disordered over two positions with site occupancies of 0.31 (2) and 0.69 (2).

(2,2'-Bipyridine-κN,N')iodido(pyrrol-idine-1-dithio-carboxyl-ato-κS,S')copper(II).

In the title compound, [Cu(C(5)H(8)NS(2))I(C(10)H(8)N(2))], the Cu(II) ion is coordinated by one iodide ion, two N atoms of the bipyridine ligand and two S atoms from the pyrrolidine-1-dithio-carboxyl-ate ligand in a distorted square-pyramidal environment.

Hydrothermal Synthesis of Co-Doped NiSe2 Nanowire for High-Performance Asymmetric Supercapacitors.

Co@NiSe2 electrode materials were synthesized via a simple hydrothermal method by using nickel foam in situ as the backbone and subsequently characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and a specific surface area analyzer. Results show that the Co@NiSe2 electrode exhibits a nanowire structure and grows uniformly on the nickel foam base. These features make the electrode show a relatively high specific surface area and electrical conductivity, and thus exhibit excellent electrochemical performance. The obtained electrode has a high specific capacitance of 3167.6 F·g-1 at a current density of 1 A·g-1. To enlarge the potential window and increase the energy density, an asymmetric supercapacitor was assembled by using a Co@NiSe2 electrode and activated carbon acting as positive and negative electrodes, respectively. The prepared asymmetrical supercapacitor functions stably under the potential window of 0⁻1.6 V. The asymmetric supercapacitor can deliver a high energy density of 50.0 Wh·kg-1 at a power density of 779.0 W·kg-1. Moreover, the prepared asymmetric supercapacitor exhibits a good rate performance and cycle stability.

A square-planar nickel dithiolate complex as an efficient molecular catalyst for the electro- and photoreduction of protons.

A square-planar nickel(ii) dithiolate complex is an active molecular catalyst for both photoreduction of protons from water with a turnover number (>1500) and electroreduction of protons from weakly acidic solutions with remarkable turnover frequencies (5575 s-1 at -1.92 V and 1441 s-1 at -1.61 V vs. SCE). DFT calculations provide in-depth insight into the catalytic cycle of the electrochemical reaction, suggesting that the sulfur atoms play crucial roles in proton exchange and hydrogen formation.

[Pb3Cu2I10(phen)4]n: a novel organic-inorganic hybrid ferromagnetic semiconductor.

An iodoplumbate-based organic-inorganic hybrid ferromagnetic semiconductor, [Pb3Cu2I10(phen)4]n, has been solvothermally synthesized. The ferromagnetic exchange interaction is resulting from the multiple aromatic π-π stacking interactions between the adjacent phen molecules.

Photocatalytic water reduction from a noble-metal-free molecular dyad based on a thienyl-expanded BODIPY photosensitizer.

A noble-metal-free molecular dyad was constructed by anchoring a thienyl-expanded BODIPY photosensitizer (PS) to a cobaloxime catalyst, which gives a 2.5-fold increase in the TON, and a 3-fold enhancement in the quantum efficiency as compared to the multicomponent catalytic system for the generation of hydrogen via the reduction of water. The stability of PS was expected to improve by introducing the thienyl moiety into the BODIPY core.

Fine Tuning of Nanocrystal and Pore Sizes of TiO2 Submicrospheres toward High Performance Dye-Sensitized Solar Cells.

In general, the properties and performance of mesoporous TiO2 are greatly dependent on its crystal size, crystallinity, porosity, surface area, and morphology; in this regard, design and fine-tuning the crystal and pore sizes of the TiO2 submicrospheres and investigating the effect of these factors on the properties and photoelectric performance of dye-sensitized solar cells (DSSCs) is essential. In this work, uniform TiO2 submicrospheres were synthesized by a two-step procedure containing hydrolysis and solvothermal process. The crystal and pore sizes of the TiO2 submicrospheres were fine-tuned and controlled in a narrow range by adjusting the quantity of NH4OH during the solvothermal process. The effect of crystal and pore size of TiO2 submicrosphere on the performance of the DSSCs and their properties including dye-loading capacity, light scattering effect, power conversion efficiency (PCE), incident photon-to-electron conversion efficiencies (IPCEs), and electron recombination were compared and analyzed. The results show that increasing pore size plays a more significant role in improving the dye-loading capacity and PCE than increasing surface area, and an overall PCE value of 8.62% was obtained for the device with a 7.0 µm film thickness based on the TiO2 submicrospheres treated with 0.6 mL of NH4OH. Finally, the best TiO2 submicrosphere based photoanode film was optimized by TiCl4 treatment, and increasing film thickness and a remarkable PCE up to 11.11% were achieved.

Discovery of polymorphism-dependent emission for crystalline boron-dipyrromethene dye.

4-Methoxycarbonylphenyl-substituted BODIPY (boron-dipyrromethene) dye gives, in the solid state, three polymorphs. In spite of the absence of any strong intermolecular interactions in all crystalline forms, the three polymorphs show different photoluminescence properties. This behavior highlights the importance of molecular arrangements of the BODIPY moieties in the crystalline state in perturbing their photophysical properties.

The layered compound poly[mu2-4,4'-bipyridyl-di-mu2-chlorido-mercury(II)].

The title compound, [HgCl2(C(10)H(8)N(2))]n, features two-dimensional [HgCl2(4,4'-bipy)]n neutral networks (4,4'-bipy is 4,4'-bipyridine), based on an octahedral Hg atom coordinated by four mu2-Cl atoms and two mu2-4,4'-bipy ligands in trans positions, yielding a HgCl(4)N(2) octahedron. The structure has mmm symmetry about the Hg atoms, with most of the atoms on at least one mirror plane, but the unsubstituted C atoms of the 4,4'-bipy rings are disordered across a mirror plane. Photoluminescent investigations reveal that the title compound displays a strong emission in the green region, which probably originates from a ligand-to-ligand charge-transfer transition.

catena-Poly[[diiodozinc(II)]-mu-4,4'-bipyridine-kappa2N:N'].

The title compound, [ZnI2(bipy)]n (bipy is 4,4'-bipyridine, C10H8N2), has been prepared by the hydrothermal reaction of ZnI2 and bipy at 433 K. Each Zn atom is coordinated by two N atoms from two different bipy ligands and by two I atoms in a distorted tetrahedral geometry, with Zn-N distances ranging from 2.068 (7) to 2.101 (8) A and Zn-I distances ranging from 2.5471 (13) to 2.5673 (13) A. The molecular structure features a zigzag polymeric chain. Face-to-face pi-pi stacking interactions between adjacent bipy ligands stabilize the structure.