The ligand coordination approach for improving the stability of low-mercury catalyst in the hydrochlorination of acetylene

Mercuric chloride supported on activated carbon(HgCl_2/AC) is used as an industrial catalyst for the hydrochlorination of acetylene. Loss of HgCl_2 by sublimating from the surface of activated carbon causes the irreversible deactivation of mercury catalyst and environmental pollution. In this work, a ligand coordination approach based on the Principle of Hard and Soft Acids and Bases(HSAB) was employed to design more stable lowmercury catalyst. The low-mercury catalysts(4% HgCl_2 loading) were prepared by using HgCl_2 and potassium halides(KX, X = Cl, I) as precursors. The HgCl_2-4KI/AC catalyst showed best catalytic stability than HgCl_2/AC and HgCl_2-4KCl/AC in the hydrochloriantion of acetylene. HgCl_2 could form more stable complex with KI,K_2HgI_4 as the main active component of the HgCl_2-4KI/AC catalyst. The characterizations of XRD and EDX analysis illustrated that the active component of HgCl_2-4KI/AC was highly dispersed on the surface of activated carbon.The sublimation rates of HgCl_2 from the catalysts verified that the active component with larger stability constant had better thermal stability. Using Hg(Ⅱ) complexes with high stability constant as the active component may be the research direction of developing highly stable low-mercury catalyst for the hydrochlorination of acetylene.

Syntheses,Crystal Structures and Luminescent Properties of Two Lanthanide Coordination Polymers Based on Bifunctional Ligand

Two lanthanide coordination polymers, [Eu（HL）（L）（H2O）2]n（1） and [Tb（H0.5L）2]n（2）, based on bifunctional 5-（1H-imidazol-1-yl） isophthalic acid（H2L）, are hydrothermally synthesized and characterized by both single-crystal and powder X-ray diffraction analyses, and FT-IR. In compound 1, the basic inorganic building unit of the coordination network is the dinuclear [Eu2（COO）6] cluster. Each [Eu2（COO）6] cluster connects four HL^- ligands and each HLligand links two [Eu2（COO）6] clusters, resulting in a 2D coordination layer. The adjacent 2 D layers are further connected via neighboring inter-layer hydrogen bonds to give a 3D supramolecular structure. In compound 2, the Tb^3＋ is coordinated to six oxygen atoms. Each Tb^3＋ ion connects six ligands and each ligand links three Tb^3＋ ions, leading to a 3D coordination polymeric network which exhibits remarkably high thermal stability up to 500℃. Furthermore, due to the successful incorporation of Tb^3＋, compound 2 displays characteristic luminescent emission in the solid state at room temperature. The combination of high thermal stability and fluorescent property of compound 2 would make it as a promising light-emitting material.

A Pair of 3D Homochiral Coordination Polymers with Open Channels Constructed by Lactic Acid Derivative Ligands and In-situ Formed Anions

With the help of in-situ formed CH_3COO- anion, a pair of 3D homochiral coordination polymers with open channels were constructed by the assembly of lactic acid derivative ligands, 1.4-DIB ligands and Cd（II） ions, namely [Cd3（（R）-CIA）2（CH3CO2）_2（1.4-DIB）2（H2O）2]·x（Guest）（1-D） and [Cd3（（S）-CIA）2（CH3CO2）2（1.4-DIB）2（H2O）2]·x（Guest）（1-L）. They contain 1D interesting ladder-like Cd-（R）-CIA（3-） chains and exhibit SHG-active behavior and photoluminescent property.

Syntheses and Crystal Structures of Two Copper(Ⅱ) Coordination Polymers Derived from Aromatic Carboxylic Acids and Bis(imidazoles)Ligands

Two compounds have been obtained by the reaction of metal（Cu（II））, 4,4＇-bis（imidazol-l-yl）diphenyl thioether（BIDPT） with two carboxylic acids, 4,4＇-oxydibenzoic acid（H2oba） and phthalic acid（H2pht）. The crystal structures of the resulting compounds, namely {[Cu（BIDPT）（oba）]·H2O}n（1） and {Cu（BIDPT）（pht）}n（2）, have been determined by single-crystal X-ray diffraction analysis. Compound 1 is of orthorhombic system, space group Pbcn with a = 27.8310（3）, b = 10.7791（1）, c = 19.3913（2）A, V = 5817.0（3） ？3 and Mr = 656.15. Compound 2 belongs to the monoclinic system, space group C2/c with a = 18.2678（2）, b = 11.0259（1）, c = 22.906（2） A, β = 97.727（2）o, V = 4571.8（8） A3 and Mr = 545.04. Structural analyses reveal that compounds 1 and 2 respectively exhibit two-dimensional（2D） wavy and corrugated layer structures. Through intermolecular hydrogen bonding, compound 1 is assembled into a 3D supramolecular structure. The thermal stability and ultraviolet spectroscopy properties of the two compounds are also investigated.

Synthesis and Crystal Structure of a New Zinc(Ⅱ)Coordination Polymer Assembled by 4-Nitrophthalic Acid and Bis(imidazol)Ligands

A new complex [Zn（4-nph）（bib）]（2n）·nH2O（1） has been obtained by the reaction of metal（Zn（Ⅱ））,1,4-bis（imidazol-1-yl）-butane（bib） with 4-nitrophthalic acid（4-H（2nph））.The crystal structure of 1 has been determined by single-crystal X-ray diffraction analysis.Compound 1 is of triclinic system,space group P1 with a = 10.3251,b = 12.4503,c = 16.6497 A,α = 88.487（3）,β = 72.529（3）,γ = 79.991（3）°,V = 2009.8（5）A^3 and Mr = 945.47.Complex 1 shows a three-dimensional（3 D） framework.Moreover,through intermolecular hydrogen bonds,compound 1 is assembled into a supramolecular structure.The thermal stability and luminescent properties of 1 are also investigated.

Syntheses,Structures and Properties of Two New Coordination Polymers with Flexible Ligands as Linkers

Two new coordination polymers,[ZnL1]n（1,H2L1 = 5-（4-pyridyl）-methoxyl isophthalic acid） and[Ni（L2）2（H2O）4]n（2,HL2 = 4-（pyridin-4-ylmethoxy）benzolic acid）,have been synthesized and characterized by elemental analysis,PXRD,IR spectra,and single-crystal X-ray diffraction.Compound 1 has a three-dimensional framework constructed by 6-bridged L1^2- anions connecting the Zn2（O2C）4 paddlewheel-like units.Compound 2 contains a mononuclear molecular unit,and the central nickel atom adopts a slightly distorted octahedral geometry by two nitrogen atoms from different L2^- ligands and four oxygen atoms from water molecules.These molecular units link each other via four types of O-H…O hydrogen bonds to form an extended three-dimensional（3D） supramolecular network.The thermal and photoluminescent properties of 1 and 2 have also been investigated.

Two Metal-organic Coordination Polymers with Rigid Bis(triazole) Ligand： Assembly, Structures, and Fluorescence Properties

Two new coordination polymers containing rigid bis（triazole）, namely, [Ni（btb）_（0.5）（nph）（H_2O）]_n（1） and [Zn（btb）（SO_4）]_n（2）（btb = 4,4a-bis（1,2,4-triazolyl-1-yl）-biphenyl, H_2nph = 3-nitrophthalic acid） have been synthesized and characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction. Complex 1 shows a 3D trinodal（3,4,4）-connected sqc69 topology. Complex 2 presents a 2D uninodal 4-connected sql network, which is further packed into a 3D supramolecular framework by C-H···O hydrogen bonds. Thermal stabilities and fluorescence properties of two complexes have been discussed in detail.

Syntheses,Crystal Structures and Luminescent Properties of Two New Zinc(Ⅱ) Complexes Based on Bifunctional Ligand

By using solvothermal method,two novel coordination polymers based on 4-（4-carboxyphen-yl）-1,2,4-triazole（Hcpt） and Zn（Ⅱ） cations,[Zn（cpt）（OH）]_n·n H_2O（FJU-32） and [Zn（cpt）（atrz）]n（FJU-33）（Hatrz = 3-amino-1,2,4-triazolate）,were synthesized and characterized by single-crystal X-ray diffraction analyses,elemental analyses,FT-IR and powder X-ray diffraction. FJU-32 crystallizes in monoclinic,space group P21/c with a = 3.7441（3）,b = 23.0384（19）,c = 11.8562（10） ？,β = 99.069（8）o,V = 1009.91（15） ？3,Dc = 1.898 g/cm3,C_9H_9N_3O_4Zn,Mr = 288.57,F（000） = 916,μ（MoKα） = 2.439 mm^（-1）,Z = 4,R = 0.0600 and wR = 0.1306 for 2412 observed reflections（I 〉 2σ（I））,and R = 0.0704 and wR = 0.1349 for all data. FJU-33 crystallizes in monoclinic space group P21/c with a = 12.7483（5）,b = 9.9922（3）,c = 9.8403（3） ？,β = 100.756（4）°,V = 1231.47（7） ？~3,Dc = 1.816 g/cm^3,C_（11）H_9N_7O_2Zn,Mr = 336.62,F（000） = 680,μ（Cu Kα） = 2.957 mm^（-1）,Z = 4,R = 0.0478 and w R = 0.1184 for 2466 observed reflections（I 〉 2σ（I））,and R = 0.0687 and w R = 0.1309 for all data. In FJU-32,Zn（Ⅱ） is coordinated to three μ3-OH groups forming an unprecedented 1D zigzag-like double chain,and the 1D double chains are connected to four neighbouring double chains by the cpt ligands to form an extended 3D porous coordination polymer. In FJU-33,the adjacent [Zn（atrz）] 2D layers are further connected by the cpt ligands via Zn–O coordinated bonds and neighboring interlayer hydrogen-bonding interactions to give rise to an overall 3D pillared layer structure. The neutron triazole group of the cpt ligand has weaker coordination ability than the triazolate anion of atrz ligand. Furthermore,FJU-32 and FJU-33 display high thermal stability up to 300 ℃,and the solid state fluorescence reveals that two new complexes are potential optical materials.

ASYMMETRIC SYNTHESIS WITH ORGANO-TITANATE REAGENTS COORDINATED BY TARTARATE-LIKE LIGAND

A series of substituted chiral benzhydrols were synthesized by the reaction of aromatic aldehydes with chiral intermediates formed from chiral titanates and arylmagnesium halides.

Syntheses,Structures,and Properties of Three New Polymers Based on Flexible and Rigid Ligands

Three new supramolecular polymers, [（IP）（H2SO4）（H2O）]（1）, [（H2SDC）（BPA）]（2） and [Mn（SDC）（IP）2]n （3）, have been constructed by three modes（rigid IP, rigid SDC ＋ flexible BPA, rigid IP ＋ rigid SDC）. Polymers 1 and 2 are supramolecular structures, assembled by hydrogen bonds and π···π interactions. X-ray structure analysis of 3 shows waved 1D chains which form a 3D supramolecular network by hydrogen bonds and π···π interactions. Solid-state properties of thermal stability, luminescent properties, and X-ray powder diffractions for these crystalline materials have also been investigated, and polymer 3 is considered to be a good stable luminescence material.

Two Novel Complexes Based on N-N Bridged Ligand:Syntheses,Crystal Structures,Fluorescence and Magnetic Property

Two novel coordination compounds,1[Zn4（L1）4（NO3）2（H2O）2]（NO3）2·2H2O and 2[Mn2（L2）2（DMF）（H2O）3]（ClO4）2·DMF（HL1 = N＇-[（1E）-pyridine-2-ylmethylidene]pyrazine-2-carbohydrazide,H2L2 = 2-hydroxy-3-methoxybenzaldehyde（pyrazin-2-ylcarbonyl）hydrazone）,based on the N-N bridged ligands were prepared and structurally characterized.Compound 1represents the[2＊2]molecular squares,in which both N atoms belonging to the N-N bridged ligands are connected to the Zn centers.The emission of compound 1 exhibits a blue shift,which can be assigned to strong electrostatic interaction between Zn^Ⅱ ions and the L1^-1.Compound 2represents a rare phenol-O bridged Mn2^Ⅱ complex.The magnetic investigation indicates weak antiferromagnetic interactions between the Mn^Ⅱ centers.

In Situ Control of Multicolor Luminescence over the Entire Visible Spectral Region in a Single Chromophore by Sol–Gel Transformation and Dynamic Metal–Ligand Coordination

Controlling multicolor luminescence in a single chromophore is of fundamental significance but remains a great challenge.In this study,a carbazole group was incorporated into terpyridine through acylamide to produce a novel chromophore(N-{4-[(2,2′:6′,2″-terpyridine)-4′-yl]benzyl}-9-hexyl-9H-carbazole-3-carboxamide,TBCC)for achieving programmable luminescence switches.Significantly different emission states,such as nonemissive,blue,green,yellow,red,and white,were achieved in situ by controlling sol–gel transformation with sonication/heat and the reversible metal–ligand coordination between TBCC and various metal salts.