The effects of amino groups and open metal sites of MOFs on polymer-based electrolytes for all-solid-state lithium metal batteries

Metal-organic frameworks(MOFs) are becoming more and more popular as the fillers in polymer electrolytes in recent years. In this study, a series of MOFs(NH_(2)-MIL-101(Fe), MIL-101(Fe), activated NH_(2)-MIL-101(Fe) and activated MIL-101(Fe)) were synthesized and added to PEO-based solid composite electrolytes(SCEs). Furthermore, the role of the —NH_(2) groups and open metal sites(OMSs) were both examined. Different ratios of MOFs vs polymers were also studied by the electrochemical characterizations. At last, we successfully designed a novel solid composite electrolyte containing activated NH_(2)-MIL-101(Fe),PEO, Li TFSI and PVDF for the high-performance all-solid-state lithium-metal batteries. This work might provide new insight to understand the interactions between polymers and functional groups or OMSs of MOFs better.

High-throughput computational screening of Cu-MOFs with open metal sites for efficient C_2H_2/C_2H_4 separation

Cost effective separation of acetylene(C_2H_2)and ethylene(C_2H_4)is of key importance to obtain essential chemical raw materials for polymer industry.Due to the low compression limit of C_2H_2,there is an urgent demand to develop suitable materials for efficiently separating the two gases under ambient conditions.In this paper,we provided a high-throughput screening strategy to study porous metal-organic frameworks(MOFs)containing open metal sites(OMS)for C_2H_2/C_2H_4 separation,followed by a rational design of novel MOFs in-silico.A set of accurate force fields was established from ab initio calculations to describe the critical role of OMS towards guest molecules.From a large-scale computational screening of 916 experimental Cu-paddlewheel-based MOFs,three materials were identified with excellent separation performance.The structure-performance relationships revealed that the optimal materials should have the largest cavity diameter around 5-10?and pore volume in-between 0.3-1.0 cm^3 g^(-1).Based on the systematic screening study result,three novel MOFs were further designed with the incorporation of fluorine functional group.The results showed that Cu-OMS and the-F group on the aromatic rings close to Cu sites could generate a synergistic effect on the preferential adsorption of C_2H_2 over C_2H_4,leading to a remarkable improvement of C_2H_2 separation performance of the materials.The findings could provide insight for future experimental design and synthesis of high-performance nanostructured materials for C_2H_2/C_2H_4 separation.

Coordination cage with structural “defects” and open metal sites catalyzes selective oxidation of primary alcohols

Coordination cages with intrinsic enzyme-like activity are a class of promising catalysts for improving the efficiency of organic reactions.We present herein a viable strategy to conveniently construct multimetallic active sites into a coordination cage via self-assembly of a pre-formed sulfonylcalix[4]arene-based tetranuclear copper(II)precursor and an amino-functionalized dicarboxylate linker.The cage exhibits a“defective”,partially open cylindrical structure and features coordinatively labile dimetallic Cu(II)sites.Modulated by this unique inner cavity environment,promising catalytic activity toward selective oxidation of primary alcohols to carboxylic acids at room temperature is achieved.Mechanistic studies reveal that the coordinatively labile dimetallic Cu(II)sites can efficiently capture and activate the substrate and oxidant to catalyze the reaction,while the confined nano-cavity environment modulates substrate binding and enhances the catalytic turnover.This study provides a new approach to designing biomimetic multifunctional coordination cages and environmentally friendly supramolecular catalysts.

Porous zinc(Ⅱ)-organic framework with potential open metal sites:Synthesis,structure and property

Reaction of Zn(NO3)2.6H2O with 5-(isonicotinamido) isophthalic acid(H2INAIP) in N,N-dimethylformamide(DMF) affords a new three-dimensional(3D) coordination polymer {[Zn(INAIP)(DMF)].0.5DMF.4H2O}n(1).The X-ray crystallographic structural analysis reveals that complex 1 is a 3D porous framework containing a potential open metal site inside the pores.Topology analysis confirms that complex 1 is a two-fold interpenetrated(10,3)-b net with both metal ion and ligand acting as 3-connecting nodes.The thermal stability,variable temperature X-ray diffraction pattern and N2 adsorption property of the complex are investigated.

Construction of metal-organic frameworks with unsaturated Cu sites for efficient and fast reduction of nitroaromatics:A combined experimental and theoretical study

Metal-organic frameworks(MOFs)functionalized with open metal sites(OMSs)have received widespread attention in various applications due to their fascinating electronic properties and unique interactions with guest molecules.However,rational tailoring of the coordination environment of metal nodes dur-ing the synthesis of MOFs remains a great challenge due to their tendency of saturated coordination with linkers.Herein,we reported the construction of three new MOFs featuring unsaturated Cu(Ⅱ)sites,namely[Cu(HCOO)(pzta)]_(n)(HL-1),{[Cu(PTA)0.5(pzta)(H_(2)O)]·2H_(2)O}_(n)(HL-2)and[Cu(NA)0.5(pzta)]_(n)(HL-3)(Hpzta=3-pyrazinyl-1,2,4-triazole;PTA=terephthalic acid;NA=1,4-naphthalene dicarboxylic acid),based on the mixed-linker strategy via specific selection of versatile Hpzta ligand and carboxylate ligands.Re-markably,the obtained MOFs exhibited excellent activity and good recyclability for the catalytic reduction of nitroaromatics under mild conditions(25℃and 1 atm).In particular,the complete conversion of 4-nitrophenol(4-NP)took only 30 s on HL-2,reaching a record-high TOF value compared with previously reported metal catalysts.The combined experimental and theoretical studies on HL-2 revealed that the open Cu site with positive-charged nature could improve the adsorption and subsequent electron trans-port between the substrates,and was responsible for the outstanding performance.This work shined lights on the further enhancement of performance for MOFs through rational OMSs construction.

Underlying mechanism of the hydrothermal instability of Cu3（BTC）2 metal-organic framework

Water induced decomposition of Cu3（BTC）2 （BTC= benzene-l,3,5-tricarboxylate） metal-organic framework （MOF） was studied using dynamic water vapour adsorption. Small-angle X-ray scattering, Fourier transform infrared spectroscopy and differential scanning calorimetry analyses revealed that the underlying mechanism of Cu3（BTC）2 MOF decomposition under humid streams is the interpenetration of water molecules into Cu-BTC coordination to displace organic linkers （BTC） from Cu centres.

A New Microporous Metal-Organic Framework for Highly Selective C2H2/CH4 and C2H2/CO2 Separation at Room Temperature

We have successfully designed and synthesized a new tetracarboxylic linker, which constructed its first three-dimensional microporous metal-organic framework （MOF）, [Cu2（DDPD）（H2O）2]·Gx （ZJU-13, H4DDPD= 5,5＇-（2,6-dihydroxynaphthalene-1,5-diyl）diisophthalic acid, ZJU=Zhejiang University, G=guest molecules） via solvothermal reaction. Due to open Cu^2＋ sites and optimized pore size, the activated ZJU-13a displays high separation selectivity for CzH2/CH4 of 74 and C2H2/CO2 of 12.5 at low pressure by using Ideal Adsorbed Solution Theory （IAST） simulation at room temperature.

The competitive and synergistic effect between adsorption enthalpy and capacity in D_(2)/H_(2)separation of M_(2)(m-dobdc)frameworks

Hydrogen isotope separation is a challenging task due to their similar properties.Herein,based on the chemical affinity quantum sieve(CAQS)effect,the D_(2)/H_(2)separation performance of M_(2)(m-dobdc)(M=Co,Ni,Mg,Mn;m-dobdc^(4-)=4,6-dioxido-1,3-benzenedicarboxylate),a series of honeycomb-shaped MOFs with high stability and abundant open metal sites,are studied by gases sorption and breakthrough experiments,in which two critical factors,gas uptake and adsorption enthalpy,are taken into consideration.Among these MOFs,Co_(2)(m-dobdc)exhibits the longest D_(2)retention time of 180 min/g(H_(2)/D_(2)/Ne:1/1/98)at 77 K because of its second-highest adsorption enthalpy(10.7 kJ/mol for H_(2)and 11.8 kJ/mol for D_(2))and the best sorption capacity(5.22 mmol/g for H_(2)and 5.49 mmol/g for D_(2))under low pressure of 1 kPa and 77 K,which make it a promising material for industrial hydrogen isotope separation.Moreover,the results indicate that H_(2)and D_(2)capacities under low pressure(about 1 kPa)dominate the final D_(2)/H_(2)separation property of MOFs.