Copper-organic Framework Constructed from Rod-shaped Secondary Building Units with Selective Sorption Property

One novel metal-organic framework [Cu2（L）（μ3-OH）]n（1, H3L = [1,1＇：3＇,1＇＇-terphenyl]-4,4＇＇,5＇-tricarboxylic acid） has been synthesized and characterized by single-crystal powder X-ray diffraction, IR and thermogravimetric analyses. Complex 1 crystallizes in orthorhombic crystal system, space group Pbca with a = 21.573（19）, b = 5.404（5）, c = 33.78（3） ？, C21H（12）O7Cu2, Mr = 503.39, V = 3938（6） A^3, Z = 8, Dc = 1.698 g·cm^-3, μ = 2.202 mm^-1, F（000） = 2016, 1.531〈θ〈25.009°, λ（Mo Kα） = 0.71073 A, T = 293（2） K, the final R = 0.0448 and wR = 0.1002. The structure of complex 1 is a three-dimensional（3D） framework based on infinite rod-shaped secondary building units and can be simplified as kgd topology. The gas adsorption measurements for N2, CO2, H2O, CH3OH and CH3CH2OH have been done. Fortunately, the selective sorption of CO2 over N2 was found at 195 K.

Solid-state phase transformations toward a metal-organic framework of 7-connected Zn_(4)0 secondary building units

In the development of metal-organic frameworks(MOFs),secondary building units(SBUs)have been utilized as molecular modules for the construction of nanoporous materials with robust structures.Under solvothermal synthetic conditions,dynamic changes in the metal coordination environments and ligand coordination modes of SBUs determine the resultant product structures.Alternatively,MOF phases with new topologies can also be achieved by post-synthetic treatment of as-synthesized MOFs via the introduction of acidic or basic moieties that cause the simultaneous cleavage/reformation of coordination bonds in the solid state.In this sense,we studied the solid-state transformation of two ndc-based Zn-MOFs(ndc=1,4-naphthalene dicarboxylate)with different SBUs but the same pcu topology to another MOF with sev topology.One of the chosen MOFs with pcu nets is[Zn_(2)(ndc)_(2)(bpy)]_(n)(bpy=4,4,-bipyridine),(6C_(bpy)-MOF)consisting of a 6-connected pillared-paddlewheel SBU,and the other is IRMOF-7 composed of 6-connected Zn40(C 00)6 SBUs and ndc.Upon post-structural modification,these pcu MOFs were converted into the same MOF with sev topology constructed from the uncommon 7-connected Zri_(4)O(COO)_(7)SBU(7C-MOF).The appropriate post-synthetic conditions for the transformation of each SBUs were systematically examined.In addition,the effect of the pillar molecules in the pillared-paddlewheel MOFs on the topology conversion was studied in terms of the linker basicity,which determines the inertness during the solid-state phase transformation.This post-synthetic modification approach is expected to expand the available methods for designing and synthesizing MOFs with controlled topologies.

A new 8-connected self-penetrating metal-organic framework based on dinuclear cadmium clusters as secondary building units

A new metal-organic framework（MOF） based on metal clusters as secondary building units（SBU）,has been synthesized and structurally characterized.The reported MOF presents an interesting 8-connected self-penetrating coordination network based on dinuclear cadmium cluster with a 4^（24）·5·6~3 topology. Moreover,the thermal stability and luminescence property of this compound have been investigated.

Synthesis, characterization and catalytic properties of mesoporous MCM-48 containing zeolite secondary building units

Mesoporous aluminosilicate MCM-48 containing zeolite secondary building units in the pore wall has been synthesized in alkaline media with a two-step procedure.The aluminosilicate precursors comprising zeolite secondary building units were first synthesized by carefully controlling reaction conditions and then were assembled using co-templates of gemini surfactant[C18H37N(CH3)2(CH2)3-N(CH3)2C18H37]2+(18-3-18)and triethanolamine(TEA).X-ray Diffraction(XRD)patterns of the as-made samples indicated that highly ordered mesostructured MCM-48 was formed.Transmission Electron Microscopy(TEM)images further verified the formation of MCM-48 with uniform cubic pore channel system having the pore opening diameter of about 25Å.Compared with the conventionally synthesized MCM-48,the as-synthesized MCM-48 sample showed an adsorption band at 520–600 cm-1 in its FT-IR spectrum,which was assigned to five-membered ring vibration from zeolite structure.This suggested the presence of zeolite building units in the pore wall.N2 adsorption data showed that the material had a much higher specific surface area(1200 m2/g)than the conventional MCM-48(1100 m2/g).Finally,the cat-alytic performance of the as-made MCM-48 was evaluated by hydrogenation dealkylation reaction of heavy aromatic hydrocarbons.Catalytic results showed that the as-made MCM-48 catalyst exhibited higher conversion than the con-ventional MCM-48 catalyst.The as-made mesostructured MCM-48 may have a potential catalytic application in the conversion of bulky molecules.

Chinese Unit Neighborhood Planning Strategies: A Case Study of Beijing

Chinese unit residential buildings can be understood as a flexible urban element, and theintroduction of its concept changed the urban structure of China. In this study, starting from the constraintsof contemporary planning contexts by Chinese historical units, the categories of historical Chinese unitresidential buildings were analyzed, and how spatial order and social ties has made Chinese units becomea common framework within which collective living takes place, how does the political strategy of theChinese government creates and constructs a particular form of spatial order in each example of Chineseunit residential buildings, and the impact on the daily life of the urban population were studied. Finally,how social relations, politics, and economic strategies confront and interact within Chinese unit residentialbuildings was explored.

Synthesis,Structure Characterization and Photoluminescence of a Novel Complex with(6,4,4)-Network [Ce_2(2,5-pydc)_3(H_2O)_2](2,5-pydc = Pyridine-2,5-dicarboxylic Acid)

A new three-dimensional supramolecular [Ce2（2,5-pydc）3（H2O）2]（1） has been hydrothermally synthesized at 180 ℃ and characterized by single-crystal X-ray diffraction.X-ray crystal analyses reveal that the compound belongs to the monoclinic system,space group P21/c,C21H13Ce2N3O14,a = 6.561（1）,b = 17.986（5）,c = 9.411（3） ,β = 95.558（5）° and Z = 2.In the structure of 1,each Ce（1） center is surrounded by 2,5-pydc ligands,forming the 6-connected node,and the 2,5-pydc ligand coordinates to the Ce（Ⅲ） in two different coordination modes.In mode 1,the four oxygen atoms of two carboxyl groups connect neighboring Ce（Ⅲ） ions,giving 4-connected（4-c） second building unit（SBU-1）.Furthermore,the structure is extended into a 2-D layer from SBU-1 by sharing Ce（1） atoms.In mode 2,the ligand coordinates to the Ce（Ⅲ） ion from the adjacent chain with the 4-connected（4-c） second building unit（SBU-2）,generating a 1-D ladder from SBU-2 by sharing Ce（1） atoms.Finally,the structure is extended into a 6,4,4-c network.Its photoluminescence property was also investigated.

Ordered Arrangement of Different Metals in Discrete and Infinite Building Blocks for Heterometallic Metal-Organic Frameworks Construction

Construction of sophisticated metal-organic frameworks(MOFs)with multiple kinds of metals is essential for further advancement of porous materials toward various applications.Order and arrangement of the metals in the secondary building units(SBUs)greatly influence the MOF structures outcome.While most of the previous heterometallic MOFs either have multiple kinds of discrete SBUs with different metals,or single kind of SBU with mixed metals inside,other forms of metal distribution still need further exploration.Herein,a bifunctional linker is applied to achieving differential coordination toward different metals.With Ce and Cu serving as the carboxylate-philic and pyrazole-philic metal ions,three heterometallic MOFs(FDM-121—FDM-123)are synthesized.In addition to the common metal arrangement modes,the new MOFs provide a joint reticulation of a discrete SBU and an infinite chain-like SBU featuring different metals in FDM-121,and an assembly from heterometallic infinite chain-like SBU in FDM-122.This study demonstrates the potential of bifunctional linkers for the design and synthesis of heterometallic MOFs and opens up the possibilities to create MOFs with tailored properties for specific applications.

Two comparable Ba-MOFs with similar linkers for enhanced CO_(2)capture and separation by introducing N-rich groups

Two new different metal-organic frameworks(MOFs)[Ba(L1)(H_(2)O)_(2)]_(n)·nH_(2)O(MOF 1)and[Ba(L2)(-n2 O)_(2)]_(n)·0.5 nDMF·0.5 nH_(2)O(MOF 2)were yielded by the assembly of oxygen-friendly Ba(Ⅱ)ions and two similar linkers,namely 2-(imidazol-1-yl)terephthalic acid(H_(2)L1)and 2-(1 H-1,2,4-triazol-1-yl)terephthalic acid(H_(2)L2).Single-crystal X-ray diffractions(XRD)indicate that MOF1 is a new three-dimensional(3 D)stacking dense network formed by the one-dimensional(1 D)rod-shaped chains and L1 linkers,whereas MOF 2 presents a 3 D nanotube porous framework with cylindrical tunnels based on the 1 D loop chains as the secondary building units(SBUs)by replacing the imidazole group in H_(2)L1 with the triazole group in H_(2)L2.As a result,MOF 2 has a higher density of active sites and Lewis acid sites in the porous surface of nanotube than MOF 1.Thereby,the CO_(2)capture and separation capacity of MOF 2 is great higher than that of CH_(4)at298 K.

Discovery of Zr-based metal-organic polygon:Unveiling new design opportunities in reticular chemistry

Metal-based secondary building unit and the shape of organic ligands are the two crucial factors for determining the final topology of metal-organic materials.A careful choice of organic and inorganic structural building units occasionally produces unexpected structures,facilitating deeper fundamental understanding of coordination-driven self-assembly behind metal-organic materials.Here,we have synthesized a triangular metal-organic polygon(MOT-1),assembled from bulky tetramethyl terephthalate and Zr-based secondary building unit.Surprisingly,the Zr-based secondary building unit serves as an unusual ditopic Zr-connector,toform metal-organic polygon MOT-1,proven to be a good candidate for water adsorption with recyclability.This study highlights the interplay of the geometrically frustrated ligand and secondary building unit in controlling the connectivity of metal-organic polygon.Such a strategy can be further used to unveil a new class of metal-organic materials.

Self-assembly of 3p-Block Metal-based Metal-Organic Frameworks from Structural Perspective

Metal-organic frameworks(MOFs) are a class of porous inorganic-organic hybrid materials, which are constructed from diverse inorganic building units and multi-functional organic ligands. Highly ordered pore structures and tailored functionalization have made MOF materials potential for applications in many fields. Among various MOF materials, 3p-block metal(Al, Ga, and In)-based MOFs exhibit higher chemical stability than divalent transition metal-based MOFs due to their higher valence. In this review, Al-MOFs and In-MOFs were mainly discussed from the perspective of categories of inorganic building blocks, coordination types, and numbers of organic ligands. This review will give intuitive guidance to the design and synthesis of novel 3p-block metal-based MOFs with potential applications.

China and the United States Should Build A New Type of Major Powers Relations——A Study on China’s U.S. Policy Thinking since the New Century

Since the reform and opening-up to the outside world, China has formed a series of guidelines and policies towards the United States, which are the theoretical foundation of China’s U.S. policy thinking in the New Century. Entering the new century, the international situation has undergone profound and complicated changes, the national strength gap between China and the United States has narrowed, their common interests have expanded, differences and contradictions have increased. Therefore, China stands for both countries to adhere to the direction of developing cooperative partnership, respect each other, abide by the promises, seek equal and mutual benefits and win-win cooperation, and mutually respect each others core interests. The future development of China-U.S. relations still face many challenges and China’s U.S. policy thinking needs to keep abreast with the times.