Synthesis and characterization of two isostructural 3d–4f coordination compounds based on pyridine‐2,6‐dicarboxylic acid and 4,4′‐bipyridine

The design and synthesis of 3d–4f heterometallic coordination polymers have attracted much interest due to the intriguing diversity of their architectures and topologies. Pyridine‐2,6‐dicarboxylic acid (H₂pydc) has a versatile coordination mode and has been used to construct multinuclear and heterometallic compounds. Two isostructural centrosymmetric 3d–4f coordination compounds constructed from pyridine‐2,6‐dicarboxylic acid and 4,4′‐bipyridine (bpy), namely 4,4′‐bipyridine‐1,1′‐diium diaquabis(μ₂‐pyridine‐2,6‐dicarboxylato)tetrakis(pyridine‐2,6‐dicarboxylato)bis[4‐(pyridin‐4‐yl)pyridinium]cobalt(II)dieuropium(III) octahydrate, (C₁₀H₁₀N₂)[CoEu₂(C₁₀H₉N₂)₂(C₇H₃NO₄)₆(H₂O)₂]·8H₂O, (I), and 4,4′‐bipyridine‐1,1′‐diium diaquabis(μ₂‐pyridine‐2,6‐dicarboxylato)tetrakis(pyridine‐2,6‐dicarboxylato)bis[4‐(pyridin‐4‐yl)pyridinium]cobalt(II)diterbium(III) octahydrate, (C₁₀H₁₀N₂)[CoTb₂(C₁₀H₉N₂)₂(C₇H₃NO₄)₆(H₂O)₂]·8H₂O, (II), were synthesized under hydrothermal conditions and characterized by IR and fluorescence spectroscopy, thermogravimetric analysis and powder X‐ray diffraction. Both compounds crystallize in the triclinic space group P. The Eu^III and Tb^III cations adopt nine‐coordinated distorted tricapped trigonal–prismatic geometries bridged by three pydc^2? ligands. The Co^II cation has a six‐coordination environment formed by two pydc^2? ligands, two bpy ligands and two coordinated water molecules. Adjacent molecules are connected by π–π stacking interactions to form a one‐dimensional chain, which is further extended into a three‐dimensional supramolecular network by multipoint hydrogen bonds.     

Syntheses,Structures, and Photoluminescence Properties of a Series of 3D Zn‐Ln Heterometallic Complexes with 2,3‐Pyrazine Dicarboxylic Acid as a Bridging Ligand

A series of 3D d–f heterometallic coordination polymers, {[Ln₂Zn(Pzdc)₄(H₂O)₆] · 2H₂O}_n [Ln = La ( 1 ), Pr ( 2 ), Nd ( 3 ), Sm ( 4 ), Eu ( 5 ), Gd ( 6 ), Tb ( 7 ), Dy ( 8 )] (H₂Pzdc = 2,3‐pyrazine dicarboxylic acid), were synthesized by one‐pot reactions under hydrothermal conditions. X‐ray crystallographical analysis and powder X‐ray diffraction analysis reveal that the complexes 1 – 8 are isostructural and adopt a multi‐parallel quadrilateral channel network structure with {4.6 · 2}₂{4 · 2.6 · 2.8 · 2}{6 · 3}2{6 · 5.8}₂ topology, in which the central Ln^III ion is nine‐coordinate by four oxygen atoms and two nitrogen atoms from four ligands and three oxygen atoms from three coordinated H₂O molecules and the central Zn^II ion is six‐coordinate by four oxygen atoms and two nitrogen atoms from four ligands. Moreover, the photophysical properties related to the electronic transition for complexes 4 , 5 , 7 , and 8 were investigated by the excitation and emission spectra as well as the emission lifetimes.     

Synthesis,Crystal Structure,and Catalytic Properties of Porous 3d‐4f Heterometallic Coordination Polymers Constructed from Pyrazine‐2,3‐dicarboxylic Acid

Reactions of pyrazine‐2,3‐dicarboxylic acid (H₂pzdc), cobalt nitrate and lanthanide (Ln) oxide under hydrothermal conditions result in four new 3d‐4f heterometal coordination polymers, namely, [Ln₂Co(pzdc)₄(H₂O)₆] · 2H₂O [Ln = La ( 1 ), Pr ( 2 ), Eu ( 3 ) and Gd ( 4 )]. All compounds were characterized by elemental analysis, infrared spectroscopy, thermal gravimetric analysis, and X‐ray diffraction. The compounds exhibit a three‐dimensional (3D) brick‐like structure with rectangular‐shaped nano‐scale channels along a axis direction, made up of wave‐like layers containing [Ln(pzdc)]⁺ units, which are connected by one‐dimensional (1D) chain of [Co(pzdc)₂]^2–. The catalytic properties of compounds 1 and 3 were investigated in the synthesis of cyanohydrins at room temperature under solventless conditions. They showed similar catalytic activities with very high conversions of benzaldehyde and high selectivity towards cyanohydrin. The control experiment without addition of the coordination polymers only reached 16 % conversion. Other aldehydes could also be converted totally under shorter reaction times also with very high selectivities for the corresponding cyanohydrins. Compound 1 could also be recycled in another catalytic cycle.     

基于二-吡嗪-(2, 3-f: 2′3′-h)-喹喔啉和吡啶-2，5-二羧酸混合配体的两个新奇金属有机超分子骨架的水热合成、晶体结构与光致发光

以二-吡嗪-(2, 3-f: 2′3′-h)-喹喔啉(Dpq)和吡啶-2,5-二羧酸(2,5-H2pda)两种混合配体与不同金属硝酸盐为原料,通过水热反应得到了两个新奇的金属有机骨架[Zn2(Dpq)2(2,5-pda)2(H2O)2]·2H2O(1)和[Cd2(Dpq)2(2,5-pda)2]·2H2O(2),并经元素分析、TG、IR、X-射线单晶衍射分析进行了表征。结构分析表明,2,5-pda采取不同的配位方式桥连金属离子分别形成了二聚物1和2D菱形网络2。在化合物1中,相邻的二聚物通过氢键和π-π堆积作用形成扭曲的a-Po超分子结构。在化合物2中,相邻的配位聚合物层通过氢键拓展成扭曲的a-Po超分子骨架,而π-π堆积起到巩固骨架的作用。化合物1和2的结构差异表明了金属离子和配体在配位聚合物自组装过程中对结构的影响。此外固态标题化合物在室温下表现出蓝色的发光性质。     

Syntheses,Structures, and Electrochemical Properties of Two Bis‐triazole‐bis‐amide‐based Copper(II) Pyridine‐2,3‐dicarboxylate Coordination Polymers

Abstract. Two bis‐triazole‐bis‐amide‐based copper(II) pyridine‐2,3‐dicarboxylate coordination polymers (CPs), [Cu(2,3‐pydc)(dtb)_0.5(DMF)] · 2H₂O ( 1 ) and [Cu(2,3‐pydc)(dth)_0.5(DMF)] · 2H₂O ( 2 ) (2,3‐H₂pydc = pyridine‐2,3‐dicarboxylic acid, dtb = N,N′‐bis(4H‐1,2,4‐triazole)butanamide, and dth = N,N′‐bis(4H‐1,2,4‐triazole)hexanamide), were synthesized under solvothermal conditions. CPs 1 and 2 show similar two‐dimensional (2D) structures. In 1 , the 2,3‐pydc anions bridge the Cu^II ions into a one‐dimensional (1D) chain. Such 1D chains are linked by the dtb ligands to form a 2D layer. The adjacent 2D layers are extended into a three‐dimensional (3D) supramolecular architecture by hydrogen‐bonding interactions. The electrochemical properties of 1 and 2 were investigated.     

Hydrothermal Syntheses and Crystal Structures of Two New Three‐dimensional Coordination Polymers Based on 4‐Pyrid‐3‐ylbenzoic Acid

Two new coordination polymers [Co₂(pbc)₄(H₂O)]_n ( 1 ) and [Mn(pbc)₂] ( 2 ) (Hpbc = 4‐pyrid‐3‐ylbenzoic acid) were obtained by hydrothermal reaction and characterized by elemental analysis, IR spectroscopy, and single‐crystal X‐ray diffraction. Compound 1 features a 3D network with a four‐connected 6⁶ net constructed from secondary building units of dinuclear cobalt. Compound 2 exhibits a six‐connected 4¹² · 6³ topology based on dinuclear manganese.     

Multidimensional Snowflake‐shaped (3, 9)‐connected Metal‐Organic Frameworks Composed of Ni3(μ3‐O) Building Blocks and Symmetry Ligand Pyridine‐3,5‐dicarboxylic Acid

A metal‐organic polymer [Ni₃(μ₃‐O)(PDB)₃]·H₂O ( 1 ) (PDB = pyridine‐3,5‐dicarboxylate), with antiferromagnetic interactions between the adjacent Ni atoms, containing trinuclear μ₃‐oxo‐bridged metal units Ni₃(μ₃‐O) have been synthesized by hydrothermal reaction of the achiral building blocks pyridine‐3,5‐dicarboxylate (3,5‐PDB) and Ni(NO₃)₂·4H₂O. Compound 1 shows a high symmetry three‐dimensional snowflake‐shaped (3, 9)‐connected topology structures in which μ₃‐oxo mixed‐valence Ni₃O(CO₂)₆ clusters act as nine‐connected nodes and PDB ligands act as three‐connected nodes.     

The first three‐dimensional FeIII–SrII heterometallic coordination polymer: poly[[diaquatetrakis(μ3‐pyridine‐2,3‐dicarboxylato)diiron(III)strontium(II)] dihydrate]

The title compound, poly[[diaqua‐1κ²O‐tetrakis(μ₃‐pyridine‐2,3‐dicarboxylato)‐2:1:2′κ¹⁰N,O²:O^2′,O³:O^3′;2:1:2′κ⁸O³:O^3′:N,O²‐diiron(III)strontium(II)] dihydrate], {[Fe₂Sr(C₇H₃O₄)₄(H₂O)₂]·2H₂O}_n, which has triclinic (P) symmetry, was prepared by the reaction of pyridine‐2,3‐dicarboxylic acid, SrCl₂·6H₂O and Fe(OAc)₂(OH) (OAc is acetate) in the presence of imidazole in water at 363 K. In the crystal structure, the pyridine‐2,3‐dicarboxylate (pydc²⁻) ligand exhibits μ₃‐η¹,η¹:η¹:η¹ and μ₃‐η¹,η¹:η¹,η¹:η¹ coordination modes, bridging two Fe^III cations and one Sr^II cation. The Sr^II cation, which is located on an inversion centre, is eight‐coordinated by six O atoms of four pydc²⁻ ligands and two water molecules. The coordination geometry of the Sr^II cation can be best described as distorted dodecahedral. The Fe^III cation is six‐coordinated by O and N atoms of four pydc²⁻ ligands in a slightly distorted octahedral geometry. Each Fe^III cation bridges two neighbouring Fe^III cations to form a one‐dimensional [Fe₂(pydc)₄]_n chain. The chains are connected by Sr^II cations to form a three‐dimensional framework. The topology type of this framework is tfj . The structure displays O—H...O and C—H...O hydrogen bonding.     

Hydrothermal Synthesis and Structural Characterization of Two Zinc Coordination Polymers of 1,2‐Di(4‐pyridyl)ethylene and Benzenedicarboxylate

Hydrothermal reactions of Zn(NO3)2•6H2O with 1,2-di(4-pyridyl)ethylene (dpe) and 1,4-benzenedicarboxylate (1,4-BDC) or 1,3-benzenedicarboxylate (1,3-BDC) in water gave rise to two new metal-organic coordination polymers, [Zn(1,4-BDC)(dpe)]n (1) and [Zn4O(1,3-BDC)3(dpe)]n (2). Both compounds were characterized by elemental analysis and IR spectroscopy, and their structures were determined by single crystal X-ray diffraction. 1 displays a rare 5-fold interpenetrating 66-diamondoid framework while 2 possesses an interlocked 3D network formed by inclined interpenetration of 2D (4,4) networks that are constructed by μ4-oxo tetrazinc Zn4O cores and the bridging dpe and 1,3-BDC ligands. Thermal and photoluminescent properties of 1 and 2 were also investigated.     

Synthesis of New C2‐Symmetric Chiral Bisamides from (1S,2S)‐Cyclohexane‐1,2‐dicarboxylic Acid

A series of new C₂‐symmetric (1S,2S)‐cyclohexane‐1,2‐dicarboxamides was synthesized from (1S,2S)‐cyclohexane‐1,2‐dicarbonyl dichloride and N‐benzyl‐substituted aromatic amines, which were prepared from 2‐aminopyridine, 2‐chloroaniline, and 2‐aminophenol via imine formation with benzaldehyde and subsequent reduction with NaBH₄. (1S,2S)‐N,N′‐Dibenzyl‐N,N′‐bis[2‐(benzyloxy)phenyl]cyclohexane‐1,2‐dicarboxamide was converted to (1S,2S)‐N,N′‐dibenzyl‐N,N′‐bis(2‐hydroxyphenyl)cyclohexane‐1,2‐dicarboxamide via hydrogenolysis in the presence of Pd(OH)₂ on active carbon powder.     

Two new cadmium(II) coordination polymers based on bis(1,2,4‐triazol‐1‐yl)alkane ligands and pyrazine‐2,3‐dicarboxylic acid

Assemblies of pyrazine‐2,3‐dicarboxylic acid and Cd^II in the presence of bis(1,2,4‐triazol‐1‐yl)butane or bis(1,2,4‐triazol‐1‐yl)ethane under ambient conditions yielded two new coordination polymers, namely poly[[tetraaqua[μ₂‐1,4‐bis(1,2,4‐triazol‐1‐yl)butane‐κ²N⁴:N^4′]bis(μ₂‐pyrazine‐2,3‐dicarboxylato‐κ³N¹,O²:O³)dicadmium(II)] dihydrate], {[Cd₂(C₆H₂N₂O₄)₂(C₈H₁₂N₆)(H₂O)₄]·2H₂O}_n, (I), and poly[[diaqua[μ₂‐1,2‐bis(1,2,4‐triazol‐1‐yl)ethane‐κ²N⁴:N^4′]bis(μ₃‐pyrazine‐2,3‐dicarboxylato‐κ⁴N¹,O²:O³:O^3′)dicadmium(II)] dihydrate], {[Cd₂(C₆H₂N₂O₄)₂(C₆H₈N₆)(H₂O)₂]·2H₂O}_n, (II). Complex (I) displays an interesting two‐dimensional wave‐like structure and forms a distinct extended three‐dimensional supramolecular structure with the help of O—H...N and O—H...O hydrogen bonds. Complex (II) has a three‐dimensional framework structure in which hydrogen bonds of the O—H...N and O—H...O types are found.     

Dramatic Solvent Effect in the Reduction of 2,3—Allenoic Acid Esters.A Simple Synthesis of 2,3—Allenols from 2,3—Allenoates

2，3－Allenols were prepared conveniently from the reduction reaction of 2,3-allenoates with DIBAL-H(Diisobutylaluminum hydride) in toluene.A dramatic solvent effect was observed for this reaction.     

A two‐dimensional copper(II) coordination polymer based on 2‐propyl‐1H‐imidazole‐4,5‐dicarboxylic acid

Single‐crystal X‐ray diffraction analysis of poly[bis(μ₂‐5‐carboxy‐2‐propyl‐1H‐imidazole‐4‐carboxylato‐κ³N³,O⁴:O⁵)copper(II)], [Cu(C₈H₉N₂O₄)₂)]_n, indicates that one carboxylic acid group of the 2‐propyl‐1H‐imidazole‐4,5‐dicarboxylic acid (H₃PDI) ligand is deprotonated. The resulting H₂PDI⁻ anion, acting as a bridge, connects the Cu^II cations to form a two‐dimensional (4,4)‐connected layer. Adjacent layers are further linked through interlayer hydrogen‐bond interactions, resulting in a three‐dimensional supramolecular structure.     

A 2D Metal‐Organic Framework Based on 9‐(Pyridin‐4‐yl)‐9H‐carbazole‐3,6‐dicarboxylic Acid: Synthesis,Structure and Properties

A metal‐organic framework (MOF ) formulated as [Cd₂(μ₃‐L)₂(DMF )₄]•H₂O ( CdL ) [H₂L =9‐(pyridin‐4‐yl)‐ 9H ‐carbazole‐3,6‐dicarboxylic acid, DMF =N ,N ‐dimethylformamide] was synthesized under solvothermal condition. Crystal structural analysis reveals that CdL features the layered 2D framework with L^{2 −} ligands as 3‐connected nodes. The compound CdL emits blue‐violet light with the narrow emission peak and the emission maximum at 414 nm upon excitation at the maximum excitation wavelength of 340 nm. The compound CdL has a similar emission spectrum curve to the free H₂L ligand that indicates the emission of compound CdL should be originated from the coordinated L^{2 −} ligands.     

Two ZnII mononuclear coordination compounds with pyridinedicarboxylate and auxiliary N‐(pyridin‐4‐ylmethylidene)hydroxylamine ligands

Two new mononuclear coordination compounds, bis{4‐[(hydroxyimino)methyl]pyridinium} diaquabis(pyridine‐2,5‐dicarboxylato‐κ²N,O²)zincate(II), (C₆H₇N₂O)₂[Zn(C₇H₃NO₄)₂(H₂O)₂], (1), and (pyridine‐2,6‐dicarboxylato‐κ³O²,N,O⁶)bis[N‐(pyridin‐4‐ylmethylidene‐κN)hydroxylamine]zinc(II), [Zn(C₇H₃NO₄)(C₆H₆N₂O)₂], (2), have been synthesized and characterized by single‐crystal X‐ray diffractometry. The centrosymmetric Zn^II cation in (1) is octahedrally coordinated by two chelating pyridine‐2,5‐dicarboxylate ligands and by two water molecules in a distorted octahedral geometry. In (2), the Zn^II cation is coordinated by a tridentate pyridine‐2,6‐dicarboxylate dianion and by two N‐(pyridin‐4‐ylmethylidene)hydroxylamine molecules in a distorted C₂‐symmetric trigonal bipyramidal coordination geometry.     

Application of Wittig Reaction in Synthesis of Novel Pyridine Dicarboxylic Acid Derivatives with High Ligand Activity

A series of novel conjugated molecules with two pyridine dicarboxylic acid units have been synthesized by a Wittig reaction of corresponding alkyltriphenylphosphonium salts with aromatic aldehydes. The novel pyridine dicarboxylic acid derivatives with high ligand activity were completely characterized from their mass and ¹H NMR spectra. The E-configuration of these alkenes was confirmed by infrared spectroscopic data.      

Hydrothermal Synthesis of Five New Coordination Polymers Based on Benzophenone‐2, 4′‐dicarboxylic Acid and N‐Donor Spacers

Five new coordination polymers, namely, [Ni₂(L)₂(4, 4′‐bipy)₃)] · H₂O]_n ( 1 ), [Ni₂(L)₂(O) (bpp)₂]_n ( 2 ), [Zn(L)(bib)_0.5]_n ( 3 ), [Zn(L)(PyBIm)]_n ( 4 ), and [Zn₃(L)₂(OH)(im)]_n ( 5 ) [H₂L = benzophenone‐2, 4′‐dicarboxylic acid, 4, 4′‐bipy = 4, 4′‐bipyridine, bpp = 1, 3‐bis(4‐pyridyl)propane, PyBIm = 2‐(4‐pyridyl)benzimidazole, and im = imidazole] were synthesized under hydrothermal conditions. Structure determination revealed that compound 1 is a 3D network and exhibits a 4‐connected metal‐organic framework with (4².6³.8) topology, whereas compounds 2 , 3 , 4 , and 5 are two‐dimensional layer structures. In compounds 2 – 4 , dinuclear metal clusters are formed through carboxylic groups. In compound 5 , trinuclear metal clusters are formed through μ₃‐OH and carboxylic groups. The carboxylic groups exhibit three coordination modes in compounds 1 – 5 : monodentately, bidentate‐chelating, and bis‐monodentately. Furthermore, the luminescent properties for compounds 3 , 4 , and 5 were investigated.     

Synthesis,crystal structure and topological analysis of a three‐dimensional polymeric network based on zinc(II), potassium and 5‐sulfobenzene‐1,3‐dicarboxylate (SIP)

Aromatic polycarboxylate linkers provide structural rigidity and strong interactions among the metal centre and the carboxylate O atoms. A new three‐dimensional coordination polymer namely, catena‐poly[potassium [tetraaqua(μ‐5‐sulfobenzene‐1,3‐dicarboxylato)zinc(II)]], {K[Zn(C₈H₃O₇S)(H₂O)₄]}_n or {K[Zn(SIP)(H₂O)₄]}_n, where SIP is 5‐sulfobenzene‐1,3‐dicarboxylate or 5‐sulfoisophthalate, was obtained and characterized by elemental analysis and IR vibrational spectroscopy, and the single‐crystal structure was determined by X‐ray diffraction analysis. The compound crystallizes in the monoclinic space group P2₁/n with Z = 4. Topological analysis revealed that K—O interactions form a two‐dimensional network, which is uninodal 4‐connected and can be described with a point symbol (4⁴.6²), and this plane network is classified as sql/Shubnikov . The layers are connected by Zn²⁺ ions coordinated to the SIP linker, forming a three‐dimensional network. This net is a trinodal (3,5,6)‐connected system with point symbol (3.4⁴.5².6².7³.8³).(3.4⁴.5².6².7).(3.7²).     

One-Pot Hydrothermal Synthesis of Two New Copper（Ⅱ） Complexes with 4-Carboxyphenoxy Acetic Acid

The one-pot hydrothermal reaction of CuCl2 with H2CPOA and 4,4＇-bpy results in two new coordination polymers, [Cu（CPOA）（4,4＇-bpy）（H2O）2]·1.5H2O （1） and [Cu2（HCPOA）4（4,4＇-bpy）4] （2） （H2CPOA=4-carboxyphenoxy acetic acid, 4,4＇-bpy=4,4＇-bipyridine） since CPOA^2- anions reach equilibrium with HCPOA^- anions in the reaction system. The crystal structure of 1 shows a triple interpenetration CdSO4-like net with 1D channel, in which lattice water molecules are located. Complex 2 is a ladder-like 1D double chain structure assembled through coordination bonds and O—H…N hydrogen bonds.     

Molecular Iodine Promoted Synthesis of New Pyrido[2,3‐d]pyrimidin‐4‐ols

A highly ef?cient synthesis of novel pyrido[2,3‐d]pyrimidin‐4‐ols was developed via an iodine‐catalyzed tandem oxidative cyclization under focused microwave irradiation. Pyrido[2,3‐d]pyrimidin‐4‐ols were obtained from easily available 2‐amino‐4‐aryl‐6‐arylnicotinamides and benzylic amines with good to excellent yields.