Building up a general selection strategy and catalytic performance prediction expressions of heteronuclear double-atom catalysts for N_(2)reduction

The severe environmental problems and the demand for energy urgently require electrocatalysis to replace Haber-Bosch for the nitrogen reduction reaction(NRR).The descriptors and important properties of single-atom and homonuclear double-atom catalysts have been preliminarily explored,but the relationship between the inherent properties and catalytic activity of heteronuclear double-atom catalysts with better performance remains unclear.Therefore,it is very significant to explore the prediction expressions of catalytic activity of heteronuclear double-atom catalysts based on their inherent properties and find the rule for selecting catalytic centers.Herein,by summarizing the free energy for the key steps of NRR on 55 catalysts calculated through the first-principle,the expressions of predicting the free energy and the corresponding descriptors are deduced by the machine learning,and the strategy for selecting the appropriate catalytic center is proposed.The selection strategy for the central atom of heteronuclear double-atom catalysts is that the atomic number of central B atom should be between group VB and VIIIB,and the electron difference between central A atom and B atom should be large enough,and the selectivity of NRR or hydrogen evolution reaction(HER)could be calculated through the prediction formula.Moreover,five catalysts are screened to have low limiting potential and excellent selectivity,and are further analyzed by electron transfer.This work explores the relationship between the inherent properties of heteronuclear double-atom catalysts and the catalytic activity,and puts forward the rules for selecting the heteronuclear double-atom catalytic center,which has guiding significance for the experiment.

Mechanistic Insights into Electrocatalytic Nitrogen Reduction Reaction on the Pd-W Heteronuclear Diatom Supported on C_(2)N Monolayer:Role of H Pre-Adsorption

The electrocatalytic N_(2) reduction reaction(eNRR)is a potential alternative to the Haber-Bosch process for ammonia(NH3)production.Tremendous efforts have been made in eNRR catalyst research to promote the practical application of eNRR.In this work,by means of density functional theory calculations and the computational hydrogen electrode model,we evaluated the eNRR performance of 30 single metal atoms supported on a C_(2)N monolayer(M@C_(2)N),and we designed a new thermodynamically stable Pd-W hetero-metal diatomic catalyst supported on the C_(2)N monolayer(PdW@C_(2)N).We found that PdW@C_(2)N prefers to adsorb H over N_(2),and then,the pre-generated hydrogen-terminated PdW@C_(2)N selectively adsorbing N_(2) behaves as the actual functioning“catalyst”to catalyze the eNRR process,exhibiting excellent performance with a low overpotential(0.31 V),an ultralow NH3 desorption free energy(0.05 eV),and a high selectivity toward eNRR over hydrogen evolution reaction(HER).Moreover,PdW@C_(2)N shows a superior eNRR performance to its monomer(W@C_(2)N)and homonuclear diatom(W_(2)@C_(2)N)counterparts.The revealed mechanism indicates that the preferential H adsorption over N_(2) on the active site may not always hamper the eNRR process,especially for heteronuclear diatom catalysts.This work encourages deeper exploration on the competition of eNRR and HER on catalyst surfaces.

Synthesis,Structure and Fluorescent Property of a New Isolated Zn6Co9 Heteronuclear Cluster Constructed by Four Kinds of Ligands

A novel zero-dimensional heteronuclear cluster based on N-（phosphonomethyl）imi- no-diacetic acid （H4PMIDA） and Phen （1,10-phenanthroline）, [Zn6Co9（PMIDA）6（Phen）6（NO3）4（H2O）6]·2NO3·16H2O, has been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectrum, thermal analysis, and single-crystal X-ray diffraction. The isolated 15- nuclearity cluster [Zn6Co9（PMIDA）6（Phen）6（NO3）4（H2O）6]^2＋ was constructed by four kinds of ligands, and its charges are balanced by NO3^–. Each isolated cluster is further extended into a 3D supramolecular network through π？？？π interaction and C–H…O hydrogen bonds. Moreover, the solid-state fluorescent property of this complex has also been investigated at room temperature.

Heteronuclear intermolecular single-quantum coherences in liquid nuclear magnetic resonance

This paper analyses the heteronuclear Cosy Revamped by Asymmetric Z-gradient Echo Detection pulse sequence. General theoretical expressions of the pulse sequence with arbitrary flip angles were derived by using dipolar field treatment and signals originating from heteronuclear intermolecular single-quantum coherences （iSQCs） in highly-polarized two spin-1/2 systems were mainly discussed in order to find the optimal flip angles. The results show that signals from heteronuclear iSQCs decay slower than those from intermolecular double-quantum coherences or intermolecular zero-quantum coherences. Magical angle experiments validate that the signals are from heteronuclear iSQCs and insensitive to the imperfection of radio-frequency flip angles. All experimental observations are in excellent agreement with theoretical predictions. The quantum-mechanical treatment leads to similar predictions to the dipolar field treatment.

Syntheses and Structures of Two Heteronuclear Complexes with Glycine {[CuEr(Gly)_5(H_2O)_2](ClO_4)_5·H_2O}_n and {[Cu_2Gd_2(Gly)_10 (H_2O)_4](ClO_4)_10·4H_2O}_n

Two one dimensional heterometallic coordination polymers {[CuEr(Gly) 5(H 2O) 2](ClO 4) 5·H 2O} n (1) and {[Cu 2Gd 2(Gly) 10 (H 2O) 4](ClO 4) 10 ·4H 2O} n (2) (Gly = glycine) were synthesized and structurally and characterized magnetically. Complex 1 crystallizes in a triclinic space group of P 1 with a =1.1769(2) nm, b =1 2289(3) nm, c = 1.4452(3) nm, α = 89.90(3)°, β = 71.88(3)°, γ = 62.15(3)°, and Z =2. The carboxyl groups of glycine molecules take two coordination modes. The first one acts as a bidentate bridging ligand only. The second is a tridentate bridge that coordinates to three different metal ions. Each erbium ion is eight coordinated, taking a distorted square antiprism arrangement. The copper ion has a square pyramidal coordination polyhedron. The topological structure of complex 2 is similar to complex 1, but there are some disparities in the bond lengths and bond angles. It is also triclinic space group of P 1 with a = 1.2479(3) nm, b = 1.4489(3) nm, c =2.0885(4) nm, α = 109.56(3)°, β = 93.75(3)°, γ = 93.54(3)°, and Z =2. Variable temperature susceptibility measurements show that there is a weak ferromagnetic interaction between the Gd 3+ and Cu 2+ ions in complex 2.

Nitrilotriacetate Bridged 3d-4f Heteronuclear Complex: Synthesis and Crystal Structure of ｛[GdCu(NTA)(H_2O)_6Cl]ClO_4·H_2O｝_n

The heteronuclear gadolinium copper complex was synthesized. Its crystal structure was determined by single crystal diffraction. The crystal crystallizes in triclinic, space group P 1, a=0 8483(1) nm, b =0 9642(2) nm, c =1 2838(2) nm, α =111 17(1)°, β = 93 52(1)°, γ =100 89(1)°, Z =2, D c=2 335 g·cm -3 . The complex appears as a zigzag 1D chain. Each gadolinium ion is coordinated by three carboxylic oxygen atoms and six oxygen atoms from H 2O. Each copper ion is chelated by NTA with its nitrogen atom and three oxygen atoms of three carboxyl groups, and coordinated by a chlorine ion. The ClO 4 - is located between the chains as a counter ion.

Syntheses and Structural Characterizations of η~5-2,4-Cyclopentadien-1-yl Di-carbonyliron Heteronuclear Bi-Metallic Complexes

The novel complexes, Cp(CO) 2FeTiCp 2Cl(1) and Cp(CO) 2FeSn(CH 2CMe 2Ph) 3(2), were synthesized and characterized by means of elemental analyses and IR spectra, Cp(CO) 2FeSn· (CH 2CMe 2Ph) 3 was additionally characterized by X ray crystal structure analysis. The results of the elemental analyses are in good agreement with the theoretical values. The IR spectra show the existence of η 5 2,4 cyclopentadien 1 yl, carbonyl and methyl groups in the title complexes. The above experimental results show that the M-M bond exists in Cp(CO) 2FeSn· (CH 2Me 2Ph) 3, while the existence of the M-M bond in Cp(CO) 2FeTiCp 2Cl is highly possible, too. Both the two complexes are rather stable towards air and moisture, easily soluble in tetrahydrofuran and toluene, while their solubilities are greatly different in n hexane.

Synthesis and Crystal Structure of Heteronuclear Complex of Copper and Ytrium with Glycine

The title complex [CuY(Gly) 5(H 2O) 2](ClO 4) 5H 2O was synthesized in aqueous solution and its crystal structure was determined by X ray diffraction method. The crystal is triclinic, space group P 1 with a =1 1751(3) nm, b =1 2410(3) nm, c =1 4448(3) nm, α =72 97(2)°, β =71 82(2)°, γ =60 96(2)°, V =1 7244(6) nm 3, Z =2, d c=2 08 g/cm 3. The crystal is composed of one dimensional chain of infinite length.

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.

Crystal Structure of a Heteronuclear Complex of Erbium-Yttrium and Glycine [ErY(GIy)_6(H_2O)_4] (ClO_4)_6·5H_2O

The title complex [ErY(Gly)_6(H_2O)4](ClO_4)_6·51H_2O has been synthesized.Its crystal structure has been determined by X-ray diffraction method.The crystal is triclinic with space group P.The unit cell parameters are as follows:a=1.1518(4) nm,b=1.4105(7) nm,c=1.5530(6) nm,α=96.61(3)°,β=102.74(3)°, γ=105.70(3)°,V=2.3277(17) nm^3,Z=2,D_(calc)=2.091 g/cm^3.The structure has been refined to a final R of 0.0785.The crystal-is an infinite chain complex,in which four carboxyl groups from glycine molecules bridge the Er^(3+) and Y^(3+) ions,and the other two carboxyl groups bridge two adjacent Er^(3+) or Y^(3+) ions.

Synthesis,Crystal Structure and Properties of a 1D Heteronuclear Cobalt-sodium Polymer with Bridging Ligand 2-(2-Hydroxy-3-methoxybenzylidene) Hydrazinecarbothioamide

A new cobalt-sodium coordination polymer [CoNa（C_9H_9N_3O_2S）_2·H_2O]_2·C_2H_3N·H_2O（1） has been synthesized with cobalt chloride,2-（2-hydroxy-3-methoxybenzylidene）hydrazinecarbothio amide（L） and sodium hydroxide.It crystallizes in the triclinic space group P1,with a = 9.972（4）,b = 10.923（4）,c = 13.489（5） ？,α = 108.005（10）,β = 92.728（10）,γ = 93.16（1）o,V = 1392.0（9） ？~3,Mr = 1151.95,Dc = 1.374 g/cm^3,Z = 2,F（000） = 592,the final GOOF = 1.126,R = 0.1091 and wR = 0.2412.Each unit molecule consists of two cobalt ions and two sodium ions bridged by four 2-（2-hydroxy-3-methoxybenzylidene）hydrazinecarbothio amide anions.The coordination environment of Co ion is CoO_2N_2S_2,giving a distorted octahedral geometry and the Na（1） ion is NaO_4N,giving a distorted square pyramidal geometry.The results show that 1 shows one strong intense fluorescence emission wavelength of 429 nm with an excitation wavelength of 376 nm,and the electron transfer of 1 is irreversible in electrode reactions.

Assembly of a Heteronuclear POM {[K_5Na_6Cu_5(Ⅱ)(CH3COO)_(20)(CH_3CN)]Cl}_n via Two Kinds of Clusters as the Basic Bridge Unit

A novel 3D hetero-nuclear framework,namely {[K_5Na_6Cu_5^（Ⅱ）（CH3COO）_（20）（CH_3CN）]Cl}_n（1）,was obtained by hydrothermal reaction.Triple metal centers（including sodium/potassium or/and copper） were coordinated to acetate anions in such two heteronuclear clusters,respectively.Moreover,nine kinds of binding modes for acetate anions were illustrated in polymer 1,with the first reported pentadentate coordination mode for acetate ligand.

Synthesis and Crystal Structure of a Heteronuclear Complex［MnSc（DTPA）（H_2O）_2］·2H_2O

The title complex, [MnSc (DTPA) (H2O)2]·2H2O (DTPA is diethylenetriaminepentaacetic acid). has been synthesized in aqueous solution. Its crystal structure has been determined by four-circle X-ray diffractometer. The crystal is monoclinic with space group P21/n. The cell parameters are as follows:α=0.7886 (3) nm, b=1.5094 (5) nm. c=1. 8162(6) nm; β=100. 32(2)°, V= 2. 121 (2) nm3 , Z= 4 , Dc =1. 75 g/cm3. In the crystal,Sc3+ ion is coordinated by five oxygen atoms and three nitrogen atoms of DTPA with coordination number eight. taking a trigondodecahedron arrangement. Mn2+ ion is coordinated by four oxygen atoms from different DTPA and two oxygen atoms from H2O molecules with coordination number six, forming an octahedron. Each Sc(DTPA) is further connected with Mn2+ ions through four carboxyl groups of DPTA serving as bridges to form a three dimensional network.

CRYSTAL STRUCTURE OF A HETERONUCLEAR LANTHANIDE COMPLEX OF ERBIUM-YTTRIUM AND GLYCINE[ErY(GlY)_6(H_2O)_4](ClO_4)_65H_2O

The title complex [ErY(Gly)_6(H_2O)_4](ClO_4)_6 5H_2O has been synthesized.Its crystal structure has been determined by X-ray diffraction method.The crystal is triclinic with space group P1.The unit cell parameters are as follows:a=11.518(4),b=14.105(7),c=15.530(6) ,α=96.61(3), β=102.74(3),γ=105.70(3)°,V=2327.7(17) ~3,Z=2,Dc=2.091g/cm^3.The structure has been refined to a final R of 0.0785.The crystal is an infinite chain complex,in which four carboxyl groups from glycine molecules bridge the Er(Ⅲ)and Y(Ⅲ)ion,other two carboxyl groups bridge two adjacent Er(Ⅲ)or two Y(Ⅲ)ions.

HETERONUCLEAR COMPLEX CONTAINING COPPER-LANTHANIDE ARRAYS: THE SYNTHESIS AND CRYSTAL STRUCTURE OF Ln_2Cu_4L_8 (HL)_4(OH)_2(CIO_4)_4(H_2O)_(10)·2CH_3COCH_3 (Ln = Tb (1), Y (2); HL = 2-Pyridone C_5H_5NO)

Reaction of 2-pyridone, copper acetate and terbium(or yttrium) perchlorate in acetone with the mole ratio 6: 2: 1 results in the formation of heteronuclear complex Ln_2Cu_4L_8 (HL)_4 (OH)_2 (ClO_4)_4 (H_20)_(10) 2CH_3COCH_3(Ln = Tb (1), Y (2)). By recrystallizing (1) in CHCl_3 single crystals were obtained and the structure was determined by four-circle diffractometer. Data showed that the crystal is in space group C2/m with a=27. 454(9)A, b=13, 608A, c=30. 556(11)A, β=99. 89(3)°, v=11245. 7(7. 5)A^3. The structure was solved by a combination of Patterson method and Fourier technique. The final R value is 0. 103. In the structure, four copper and two terbium ions are bridged by 2-pyridone anions to form an essentially octahedral Cu_4Tb_2 core. The terbium atoms are each eight-coordinate and the copper atoms are five-coordinate.

Heteronuclear-filtered ^(1)H homonuclear multi-quantum correlation experiment at 100 kHz magic-angle spinning Dedicated to Professor Chaohui Ye on the occasion of his 80th birthday

Remarkable advances in fast magic-angle spinning(MAS)techniques significantly improve the resolution of^(1)H solid-state nuclear magnetic resonance(NMR)spectra.Here,we introduce a heteronuclear-filtered^(1)H homonuclear multi-quantum(MQ)correlation strategy available at a MAS rate of 100 kHz by combining^(1)H{X}heteronuclear-filtered methods and^(1)H homonuclear MQ correlation experiments.The proposed strategy was applied to selectively extract^(1)H signals of aluminum lactate(Al-Lac)in a mixture of Al-Lac and zinc lactate(Zn-Lac)using 27Al-filtered methods(i.e.,^(1)H{27Al}heteronuclear multiple quantum correlation(HMQC)or^(1)H{27Al}symmetry-based resonance-echo saturationpulse double-resonance(S-RESPDOR)).We demonstrate that incorporating these 27Al-filtered methods into two-dimensional(2D)^(1)He^(1)H double-quantum(DQ)/single-quantum(SQ),triple-quantum(TQ)/SQ,and even three-dimensional(3D)27Al/^(1)H(DQ)/^(1)H(SQ)experiments can facilitate the acquisition of spectra without signal overlap and targeted characterization of the^(1)H species surrounding 27Al sites.The proposed strategy is considered to efficiently extract key structural information from complex spin systems.

Synthesis,Structure and Photophysical Properties of Heteronuclear Pt_2Cu Alkynyl Complexes

Two luminescent hetero-trinuclear complexes [Pt2Cu（μ-dpppy）2（C≡CC6H4R-4）4]（Cl O4）（R = H,1;R = CH3,2;dpppy = 2,6-bis（diphenylphosphino）pyridine） have been synthesized and characterized by elemental analyses,ESI-MS,^1H and ^31P{^1H} NMR spectroscopy,and X-ray crystallography for 2.Their photophysical properties in the solid state and in solutions at room temperature and in frozen glasses at 77 K were studied.Both complexes 1 and 2 show strong orange-red emission in the solid state at room temperature and in frozen glasses at 77 K,and weak emission in solutions.

A Three-dimensional Tm(Ⅲ)-Zn(Ⅱ)Heteronuclear Metalorganic Framework Based on Imidazole-dicarboxylate Ligand:Synthesis,Crystal Structure and Luminescence Property

A d-f heteronuclear metal-organic framework（MOF）,{[Tm3Zn6（bipy2）2（mimda）7（H2O）3]·（H2O）5}n（1,H3 mimda = 2-methyl-1-H-imidazole-4,5-dicarboxylic acid,and bipy = 4,4？-bipyridine）,has been synthesized under solvothermal conditions,and structurally characterized by elemental analysis,IR spectra and X-ray single-crystal diffraction.It crystallizes in orthorhombic system,space group Pnma with a = 16.1102（9）,b = 33.5805（19）,c = 16.8593（10） ？,β = 97.344（11）°,V = 9120.7（9） ？-3,Z = 4,F（000） = 5184,the final R = 0.0530 and w R = 0.1306.In complex 1,the Tm（Ⅲ） ions adopt two types of coordination fashions.Complex 1 shows onedimensional（1-D） Tm-Zn heteronuclear zigzag chains,and these chains are further linked by H3 mimda ligands into Tm-Zn heteronuclear 2-D lattice-like arrays.The 2-D heteronuclear units were connected through [Zn6（mimda）6] rings to give rise to the Tm-Zn heteronuclear cages.Finally,H3 mimda ligands connected the cages into a 3-D heterometallic framework by the combination of [TmO7]n and Tm-Zn heteronuclear cages.In addition,the thermal stability and luminescent property have been investigated.

Synthesis and Crystal Structure of a Heteronuclear Erbium and Yttrium Complex with Proline: [ErY(pro)_6(H_2O)_6] (ClO_4)_6

The title complex was synthesized in an aqueous solution at pH=3. 5,and its crystal structure was determined by X-ray diffraction methods. The com-plex is triclinic with space group P1, formula C30H66O42N6Cl6ErY, Mr,= 1651. 76, a=9. 860(2), b=13. 020(5), c= 13. 632(5) A ; a= 109. 32(3), β=110. 19(2), γ=100. 96(2)°, V= 1456(1 ) A3, Dc= 1. 884 g/cm3, Z= 1, F(000) =833, P= 2. 812mm-1 ;R=0. 046, wR(F2) =0. 123 for 4897 reflections with I>2(I). The complexis of an infinite chain structure with the neibouring metal ions connected by two bridging carboxyl groups from two different proline molecules. The erbium ion and the yttrium ion statistically lies at the position of the metal ion with M=1/2(Er+Y).

An interesting synergistic effect of heteronuclear dual-atom catalysts for hydrogen production:Offsetting or promoting

To elucidate the synergistic effect of dual-atom catalysts(DACs)at the microscopic level,we propose and construct a prototype heteronuclear system,CuNi/TiO_(2),in which the two elements of a pair have significantly different d electron-donating abilities,as a piece in the puzzle.Using density functional theory calculations,we investigate charge-dependent configurations of Cu-Ni dimers anchored on TiO_(2)by the mixing of individual constituent atoms.The d electron-donating ability determines deposition sequence and position of transition metal atoms on oxides,establishing dimer pattern and metal-support interactions.The interaction between Cu and Ni,beyond the coordination environment,predominately contributes to the synergistic effect.A complex adsorption-reduction behavior of H species on CuNi/TiO_(2)is observed.The reaction mechanism and catalytic activity of CuNi/TiO_(2)for hydrogen production are explored.At room temperature and high H coverages,CuNi/TiO_(2)shows better performance and efficiency than Ni1/TiO_(2).Our findings provide a new understanding of the synergistic effect on structure-activity relationships of supported dimers,which would be beneficial in the future design of various DACs or even atomically dispersed metal catalysts.