High-Resolution Mass Spectroscopy for Revealing the Charge Storage Mechanism in Batteries: Oxamide Materials as an Example

The pursuit of high-performance electrode materials is highly desired to meet the demand of batteries with high energy and power density.However,a deep understanding of the charge storage mechanism is always challenging,which limits the development of advanced electrode materials.Herein,high-resolution mass spectroscopy(HR-MS)is employed to detect the evolution of organic electrode materials during the redox process and reveal the charge storage mechanism,by using small molecular oxamides as an example,which have ortho-carbonyls and are therefore potential electrochemical active materials for batteries.The HR-MS results adequately proved that the oxamides could reversibly store lithium ions in the voltage window of 1.5–3.8 V.Upon deeper reduction,the oxamides would decompose due to the cleavage of the C–N bonds in oxamide structures,which could be proved by the fragments detected by HR-MS,^(1)H NMR,and the generation of NH_(3)after the reduction of oxamide by Li.This work provides a strategy to deeply understand the charge storage mechanism of organic electrode materials and will stimulate the further development of characterization techniques to reveal the charge storage mechanism for developing high-performance electrode materials.

Heterometallic Trinuclear Ni_2Zn and Ni_2Mn Complexes of Macrocyclic Oxamide: Synthesis and Crystal Structures

Two novel heterometallic trinuclear complexes of macrocyclic oxamide [Mn（NiL）2（HBTC）H2O] （1） and [Zn（NiL）2（HBTC）H2O] （2） （NiL, H2L = 2,3-dioxo-5,6,14,15-dibenzo-1,4,8,12-tetraazacyclo-pentadeca-7,13-dien, H3BTC = 1,3,5-benzenetricarboxylic acid） have been solvothermally synthesized and structurally characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. For 1, the crystals crystallize in the monoclinic system, space group P21/c with a = 11.3595（5）, b = 23.1498（11）, c = 17.2558（8） and =101.2530（10）°. For 2, the crystals crystallize in the monoclinic system, space group P21/c with a = 11.5214（8）, b = 20.6566（14）, c = 18.4126（13） and = 92.6770（10）°. The structures of 1 and 2 have oxamido-bridged trinuclear [NiⅡ2MⅡ] units and consist of two-dimensional supramolecular architectures formed by strong O–H…O intermolecular hydrogen bonds.

Syntheses and Structures of Two Coordination Polymers Containing Macrocyclic Oxamide and Isophthalic Acid Derivatives

Two novel coordination polymers [Cd（NiL）（aipt）]（1） and [Mn（nipt）（NiL）2]？H2O（2）（NiL, H2L=2,3-dioxo- 5,6,14,15-dibenzo-1,4,8,12-tetraazacyclo-pentadeca-7,13-dien, H2aipt=5-aminoisophthalic acid, H2nipt=5-nitroisoph- thalic acid） were hydrothermally synthesized and characterized by single-crystal X-ray diffraction. Compounds 1 and 2 consist of different 1D chains including both oxamide and 5-aminoisophthalate or 5-nitroisophthalic bridge. And all these chains were further interlinked via hydrogen bonds, resulting in a 2D architecture in compounds 1 and 2.

Synthesis,Structure and Luminescence of Zn_(4.5)Cu_3 Heteronuclear Coordination Polymer Comprising Macrocyclic Oxamide and 5-Sulfosalicylic Ion

The complex [Zn4.5（SSA）3（CuL）3（H2O）6]n was synthesized and structurally determined, where SSA is fully deprotonated 5-sulfosalicylic acid（CuL, H2L=2,3-dioxo-5,6,14,15-dibenzo-1,4,8,12-tetraazacyclo-pentadeca- 7,13-dien）. The title complex crystallized in the triclinic system with space group P1^-, a=1.19788（17） nm, b=1.4253（2） nm, c=2.2890（4） nm, α=90.211（2）°, ,β=93.076（2）°, γ=90.600（2）°. The complex displayed a 1D ladderlike chain. All these 1D chains were further interlinked via hydrogen bonds, resulting in a 2D architecture. The luminescent property of the compound was also discussed.

SYNTHESIS AND STRUCTURE OF A NOVEL INFINITE-LAYER COPPER(Ⅱ)COMPLEX BRIDGED BY OXAMIDE AND PYRIMIDINE

The complex polymer[Cu_2(oxap)(pyr)_2]_n(ClO_4)_(2n),where oxap^(2-)stands for N,N' -bis(2—aminopropyl)oxamide,have been synthesized.It crystallizes in monoclinic system, space group P2_1/C,with a=8.721(2),b=8.679(2),c=16.741(2),β=98.59(0),Z=4.The least-square refinement coverged at R=0.054,R_w=0.055 with 1869 unique reflections.The whole structure of the complcx consists of layers of two-dimensional network arraying along a-axis with perchlorate ions interspersed in the gap between layers.Inside the layer. trans-oxamide-bridged copper(Ⅱ)dimers connected by pyrimidine in an asymmetric fashion spread out along be plane to form an infinite two-dimensional network.

SYNTHESIS AND CRYSTAL STRUCTURE OF THE FIRST THREE DIMENSIONAL NETWORK CU(Ⅱ) COMPLEX BRIDGED BY BOTH OXAMIDE AND AZIDE

A novel three dimensional network complex polymer [Cu_4(oxen)_2(N_3)_3]_n(ClO_4)_n·2nH_2O, where oxen is N,N' -bis(2-aminoethyl)oxamide dianion, has been synthesized. It crystallizes in triclinic system, space group P, with a=11.486(2), b=11.706(3), c=12.291(3) , α=77.42(2), β=67.59(2), γ=77.96(2)°, and z=2. The least-square refinements converged at R=0.047, with 3416 observed unique reflections. The complex has a pronounced three-dimensional character and can be viewed as the tetranuclear asymmetric repeating units through inversion and translation operations to extend a three-dimensional network. The structure of Cu_4 asymmetric unit consists of two square planar and two square pyramidal Cu central atoms linked by both azide ligands in end-on and end-to-end bonding modes, and oxamidate bridge in trans conformation.

Synthesis and Crystal Structure of the First Example of a Tris-Chelated Co(II) Complex Based on Oxamide Dioxime Ligand

A new cobalt(II) complex, [Co(H2 oxado)3 ]C2 O4 H2 oxado·2H2 O (H2 oxado = oxamide dioxime), has been synthesized in aqueous solution and characterized by elemental analysis and single crystal X-ray structure determination. The complex crystallizes in the triclinic space group P-1, with the parameters a = 9.46(4), b = 11.84(5), c = 12. 81(5)?&Aring, α = 104.94(6), β = 99.29(5), γ = 106.73(5), V = 1284(9) &Aring3, Z = 2. The central cobalt(II) cation is pseudo-octahedrally coordinated by six imino N atoms of the neutral oxamide dioxime ligand. In the solid state, each of the following bricks, namely the cationic complexes, the oxalate dianions as well as the oxamide dioxime crystallization molecules, pile up parallel to the a axis. The bulk structure is consolidated by an extended three-dimensional network of hydrogen bridgings—that link the ionic partners, oxamide dioxime and water molecules to one another—and by coulombic interactions.

Four-step spin-crossover in an oxamide-decorated metal-organic framework

Spin-crossover(SCO)complexes with multiple spin states are promising candidates for high-order magnetic storage and multiple switches.Here,by employing the N,N'-4-dipyridyloxalamide(dpo)ligand,we synthesize two Hofmann-type metal-organic frameworks(MOFs)[Fe(dpo){Ag(CN)_(2)}_(2)]·3DMF(1)and[Fe(dpo){Ag(CN)_(2)}_(2)]·0.5MeCN·2DEF(2),which exhibit guest dependent four-step SCO behaviors with the sequences of LS→~LS_(2/3)HS_(1/3)→LS_(1/2)HS_(1/2)→~LS_(3/10)HS_(7/10)→HS and LS→~LS_(2/3)HS_(1/3)→LS_(1/2)HS_(1/2)→~LS_(1/4)HS_(3/4)→HS,respectively.Therefore,the incorporation of hydrogen-donating/hydrogen-accepting groups into the Hofmann-type MOFs may effectively explore the multi-step SCO materials by tuning hydrogen-bonding interactions.

Accelerating photocatalytic hydrogen evolution and pollutant degradation by coupling organic co-catalysts with TiO_2

Accelerating the separation efficiency of photoexcited electron-hole pairs with the help of highly active co-catalysts has proven to be a promising approach for improving photocatalytic activity. Thus far, the most developed co-catalysts for semiconductor-based photocatalysis are inorganic materials;the employment of a specific organic molecule as a co-catalyst for photocatalytic hydrogen evolution and pollutant photodegradation is rare and still remains a challenging task. Herein, we report on the use of an organic molecule, oxamide (OA), as a novel co-catalyst to enhance electron- hole separation, photocatalytic H2 evolution, and dye degradation over TiO2 nanosheets. OA-modified TiO2 samples were prepared by a wet chemical route and demonstrated improved light absorption in the visible-light region and more efficient charge transport. The photocatalytic performance of H2 evolution from water splitting and rhodamine B (RhB) degradation for an optimal OA-modified TiO2 photocatalyst reached 2.37 mmol g^–1 h^–1 and 1.43 × 10^-2 min^-1, respectively, which were 2.4 and 3.8 times higher than those of pristine TiO2, respectively. A possible mechanism is proposed, in which the specific π-conjugated structure of OA is suggested to play a key role in the enhancement of the charge transfer and catalytic capability of TiO2. This work may provide advanced insight into the development of a variety of metal-free organic molecules as functional co-catalysts for improved solar-to-fuel conversion and environmental remediation.

One and Two-dimensional Structures of a New Oxamido Copper(II) Complex with Phthalato Bridged

A new o-phthalato-bridged oxamide copper（Ⅱ） complex 1, {[Cu2（oxap）]（pht）. 4H2O}n （oxap=N, N＇-bis（2-aminopropyl）oxamide, pht= phthalate dianion）, has been prepared and structurally characterized. It crystallizes in monoclinic, space group C2/c with a=23.424（4）, h=7.9696（14）, c=15.727（3）A°,β=129.617（2）°, C16H28Cu2N4O10, Mr=563.50, V=2261.6（7） A°, Z=4, Dc=1.655 g/cm^3, μ（MoKα）=1.939 mm^-1, F（000） = 1160, the final R=0.0393 and wR=0.0928 for 1707 observed reflections with I〉2σ（1）. Single-crystal X-ray analysis reveals that 1 displays a one-dimensional zigzag chain structure, in which each Cu（oxap） moiety adopting trans-conformation is connected by ,μ1,6-phthalate anion bridges, and these zigzag chains are further linked by another ,μ1,6-phthalate anion bridge to form a 2D sheet structure. The polar guest water molecules reside in the inter-and intrasheets to stabilize the whole crystal structure.

Synthesis and Crystal Structure of Unprecedented Pentanuclear Cu_5~Ⅱ Complex Containing both Macrocyclic and Azido Ligands

The organic-inorganic hybrid complex with formula [（CuL）2Cu3（μ-1,1-N3）4（ClO4）2], complex 1, {CuL, [5,6：14,l5-dibenzo-1,4,8,12-tetraazacyclopentadeca-7,3-diene-2,3-dione（2-）]copper（Ⅱ）}, has been synthesized and structurally determined. The crystals of complex 1 crystallize in the triclinic system with space group P1, a=0.92983（12） nm, b=1.09644（14） nm, c=1.27396（16） nm, α=70.782（2）°β=86.266（2）°,γ=78.284（2）°. In this complex, the five copper ions are bridged by macrocyclic oxamide groups and azido. Furthermore, C-H…O hydrogen bond interactions link the pentanuclear fragments to form a 2D supramolecular architecture.

Crystal Structure and Magnetic Properties of the Oxamidato-bridged Cu_3 Complex Containing Macrocyclic Ligands

One novel oxamido-bridged trinuclear complex [Cu（CuL）2（ClO4）2] has been syn-thesized and structurally determined.It crystallizes in the monoclinic system,space group P21/n with a = 10.636（4）,b = 11.645（4）,c = 16.038（6） ,β = 91.029（5）°,V = 1986.2（12） 3,C38H32Cl2Cu3N8O12,Mr = 1054.24,Dc = 1.763 Mg/m3,μ（MoKα） = 1.802 mm-1,F（000） = 1066,Z = 2,the final R = 0.0328 and wR = 0.0882 for 3152 observed reflections.The crystal structure is a trinuclear complex in which the CuII ions are bridged by macrocyclic oxamide groups.C-H···O hydrogen bonding interactions link the trinuclear fragment to form a 2D supramolecular architecture.Magnetic measurements indicate that the compound is moderately antiferromagnetically coupled.

Structure and Magnetic Properties of a Tetranuclear Copper(II) Cluster Containing Dissymmetrical Oxamidate Ligand

A new tetranuclear copper（ Ⅱ） compound containing dissyrnmetrical oxamidate ligand was synthesized and structurally characterized by IR spectroscopy, elemental analysis, single-crystal X-ray diffraction, and magnetic properties. The title compound 1 crystallizes in triclinic, space group P^-1 with a = 8.9547（9）, b = 11.7018（9）, c = 12.0288（10） A, a = 110.1790（10）, β = 100.0700（10）, ）, = 100.6780（10）°, V= 1122.97（17）A^3, C34H48C12Cu4N10O16, Mr = 1177.92, Dc = 1.742 g/cm^3,μ（MoKa） = 2.067 mm^-1, F（000） = 600, Z = 1, the final R = 0.0391 and wR = 0.1073 for 3904 observed reflections （I 〉 2σ（I））. In the structure, complex 1 consists of a tetranuclear unit and two perchlorate anions. Furthermore, its magnetic properties have also been investigated.

New carbon nitride close to C_(6)N_(7) with superior visible light absorption for highly efficient photocatalysis

The rational design and construction of novel two-dimensional(2D)carbon nitrides(CNs)beyond g-C_(3)N_(4) is a hot topic in the fields of chemistry and materials.Inspired by the polymerisation of urea,we have prepared a series of novel C-C bridged heptazine CNs UO_(x)(where x is the ratio of urea to oxamide,x=1,1.5,2,2.5,and 3),which are similar to(C_(6)N_(7))n,upon the introduction of oxamide.As predicted using density functional theory(DFT)calculations,the conjugated structure of UO_(x) was effectively extended from an individual heptazine to the entire material.Consequently,its bandgap was reduced to 2.05 eV,and its absorption band edge was significantly extended to 600 nm.Furthermore,its carrier transfer and separation were significantly enhanced,establishing its superior photocatalytic activity.The optimised UO_(2) exhibits a superior photocatalytic hydrogen production rate about 108.59 lmol h^(-1)(using 10 mg of catalyst)with an apparent quantum efficiency(AQE)of 36.12%and 0.33%at 420 and 600 nm,respectively,which is one of the most active novel CNs reported to date.Moreover,UO_(2) exhibits excellent photocatalytic activity toward the oxidation of diphenylhydrazine to azobenzene with conversion and selectivity reaching~100%,which represents a promising highly efficient 2D CN material.Regarding phenols degradation,UO_(2) also displayed significantly higher activity and durability during the degradation of phenol when compared to traditional g-C_(3)N_(4),highlighting its significant potential for application in energy,environment and photocatalytic organic reactions.