Polymorphism in crystalline cinchomeronic acid

The structural relationship between the two crystal forms of cinchomeronic acid (CA 3,4-dicarboxypyridine) has been investigated by single crystal X-ray diffraction, IR and Raman spectroscopy and solid state NMR spectroscopy, showing that the two polymorphs form a monotropic system, with the orthorhombic form I being the thermodynamically stable form, while the monoclinic form II is unstable. In both forms CA crystallizes as a zwitterion and decomposes before melting. The crystal structure and spectroscopic analysis indicate that the difference in stability can be ascribed to the strength of the hydrogen-bonding patterns established by the protonated N-atom and the carboxylic/carboxylate O-atoms.     

1,4-二氢-2,6-二甲基-3,5-吡啶二甲酸二乙酯的合成

用季铵盐作相转移催化剂,在较温和的条件下使乙酰乙酸乙酯与甲醛和氨缩合,合成了1,4－二氢－2,6－二甲基－3,5－吡啶二甲酸二乙酯（DHP）,研究了多种反应因素对产物的影响,提出了合成DHP的最佳工艺条件,投料摩尔比mol乙酰乙酸乙酯：mol六次甲基四胺＝2：1.5,20％（wt％）乙醇水溶液作溶剂,反应温度55℃,反应时间45min,产品收率达88％。     

Synthesis and structural characterization of diorganotin(IV) complexes with 2,6‐pyridinedicarboxylic acid

Two new diorganotin(IV) derivatives of 2,6‐pyridinedicarboxylic acid, {[Ph₂Sn(2,6‐C₅H₃N)(COO)₂][Na(2,6‐C₅H₃N)(COOH) (COO)(CH₃OH)₂]} ( 1 ) and [Me₂Sn(2,6‐C₅H₃N)(COO)₂(H₂O)]^•H₂O ( 2 ) were synthesized by the reaction of Ph₃SnCl and PhMe₂SnI with 2,6‐pyridinedicarboxylic acid, respectively in the presence of sodium methoxide or potassium iso‐propoxide. The prepared compounds were characterized by mass spectrometry, IR, ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopies. The molecular structures of both complexes were determined by a single‐crystal X‐ray analysis. The X‐ray structure revealed pentagonal bipyramidal geometry around the tin atom for compound 1, which is incorporated with a hexacoordinated monosodium derivative of 2,6‐pyridinedicarboxylic acid. Complex 2 adopts a monomeric structure with two carboxylate oxygen atoms coordinated to tin in monodenate form from equatorial positions, and the coordination number is raised to six as the oxygen of water and pyridine nitrogen occupies the other equatorial positions of octahedron. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis and Crystal Structure of Bis[（2,6—pyridinedicar—boxylato）（methanol）dibenzyltion（Ⅳ）]

A novel seven‐coordinate dimer bis[(2,6‐pyridinedicarboxylato)(methanol)dibenzyltin(IV)] was synthesized by the reaction of (PhCH₂)₃SnCl with 2,6‐pyridine dicarboxylic acid in 1:1 molar ratio in methanol solution. The structure was characterized by elemental analysis, IR and ¹H NMR spectra, and the crystal structure was determined by X‐ray single crystal diffraction analysis. The crystal belongs to monoclinic space group P2₁/n, a =0.96250(19) nm, b = 1.0947(2) nm, c = 1.9965(4) nm, β = 92.31(3)°, Z = 2, V = 2.1019(7) nm³, D_c = 1.574 g/cm³, μ = 1.248 mm^?1, F(000)=1000, R₁ = 0.0675, wR₂ = 0.0836. In the crystals of the complex, each tin atom is seven‐coordinated in a distorted bipyramidal structure.     

Preparation and thermal reactivity of hydrazinium 2,n-pyridinedicarboxylates (n=3, 4, 5 and 6)

Hydrazinium 2,n-pyridinedicarboxylates of general compositions N₂H₅HA, (N₂H₅)₂A·H₂O and N₂H₅HA·H₂A, where H ₂ A=2,n-pyridinedicarboxylic acid (n=3, quinolinic acid;n=4, lutidinic acid; n=5, isocinchomeronic acid and n=6, dipicolinic acid) have been prepared by the neutralisation of aqueous solution of hydrazine hydrate with the respective acids, in stoichiometric ratios. Formation of these hydrazinium derivatives has been confirmed by analytical, IR spectral and thermal studies. Among these, the monohydrazinium salts are anhydrous whereas the dihydrazinium salts are monohydrated. While lutidinic and dipicolinic acids form all the three types of salts, the quinolinic and isocinchomeronic acids do not form N₂H₅HA·H₂A and N₂H₅HA, respectively, except the other two types. Infrared spectra of these salts reveal N-N stretching frequencies of the hydrazinium ion in the region 970-950 cm^-1. The simultaneous TG and DTA of these salts show that all of them decompose without clear melting and lose hydrazine endothermically between 200 and 280°C, except dihydrazinium isocinchomeronate monohydrate in which half of the hydrazine molecule is lost exothermically, to give pyridinemono- or dicarboxylic acid intermediate which further decomposes exothermically to gaseous products. This revised version was published online in August 2006 with corrections to the Cover Date.     

1,4-二氢-2,6-二甲基-4-(3-硝基苯基)-3,5-吡啶二羧酸二(2-甲氧基乙基)酯的合成

对1，4－二氢吡啶类钙拮抗剂西尼地平进行了结构修饰。以双乙烯酮和乙二醇单甲醚为原料，经酯化、缩合、氨化和Hantzsch环化等反应合成了1，4－二氢－2，6二甲基－4－（3－硝基苯基）－3，5－吡啶二羟酸二（2－甲氧基乙基）酯，总收率71％。目标产物结构经^1H NMR和MS确证。     

Two Isostructural 2-D Metal(Ⅱ)-organic Coordination Polymers from 4,4'-Bipyridyl and (E)-2,6-Dimethyl-4-styrylpyridine-3,5-dicarboxylic Acid

(E)-2,6-Dimethyl-4-styrylpyridine-3,5-dicarboxylic acid (H2mspda) is firstly employed in coordination chemistry.Two isostructural two-dimensional (2-D) 4-connected metal-organic coordination polymers with a general formula of {M2[(mspda)2(bpy)(H2O)2]}n (M=Zn(1) and Co(2)) are assembled from H2mspda,4,4'-bipyridyl (bpy),zinc and cobalt ions under hydrothermal conditions,and characterized by single-crystal X-ray diffraction analyses.Complex 1 crystallizes in monoclinic,space group P21/n with a=14.551(4),b=10.941(3),c=14.945(4),β=98.817(4)o,V=2351.3(1)3,Dc=1.511 g/cm3,μ(MoKα)=1.090 mm-1,F(000)=1104,Z=4,the final R=0.0335 and wR=0.0485 for 3296 observed reflections (I 2σ(I)).In compound 1,mspda2-spacers are only arrayed in a head-to-tail fashion which corresponds to a 2-D coordination polymer.Solid-state H2mspda and complex 1 have expected photoluminescence (λem=475～496 nm) at room temperature.     

吡啶-3,5-二羧酸镍(Ⅱ)配合物的合成、结构、性质及密度泛函研究(英文)

以吡啶-3,5-二羧酸、2,2′-联吡啶和硝酸镍为原料,使用水热法合成2个配合物:[Ni(pdc)(bpy)(H2O)3]·2H2O(1)和{[Ni(pdc)(bpy)]·H2O}n(2)。配合物结构经过X射线单晶衍射分析确定都属于单斜晶系,P21/c空间群。晶体1为单核结构,利用氢键连接为三维网状分子。晶体2中二价镍离子为五配位,由吡啶二羧酸阴离子连接为二维平面结构。对化合物1、2进行了红外、紫外和变温磁化率分析。并利用密度泛函方法对2的电子结构和轨道能量进行计算,计算结果与紫外光谱数据基本符合。     

Synthesis,Crystal Structure,Magnetic Property and DFT Study of a Novel 2D Polymer [Cu(pdc)(bpy)]·H_2O

A new copper complex [Cu(pdc)(bpy)]·H2 O(1, H2 pdc = 3,5-pyridinedicarboxylic acid, bpy = 2,2-bipyridine) has been solvothermally synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy, UV-vis spectroscopy and magnetic measure- ments. Complex 1 crystallizes in monoclinic system, space group P21 /c, a = 10.893(2), b = 7.3641(15), c = 1.9921(4), β = 92.16(3), V = 1596.9(6)3, Dc = 1.676 g/cm3, Mr = 402.84, Z = 4, F(000) = 820, μ = 1.404 mm-1, the final R = 0.0237 and wR = 0.0693. The Cu(II) ion is five-coordinated by two O atoms from two pdc ligands, one N atom from another pdc ligand and two N atoms from the bpy ligand. The pdc anion, which acts as a tridentate ligand, links three Cu ions, forming(3,3)-connected two-dimensional(2D) sheets. We also studied the electronic structure and orbital energies of complex 1 by DFT methods, and the results are consistent with UV-vis spectrum.     

Synthesis and Crystal Structure of Bis[(2,6-pyridinedicarboxylato)(methanol)dibenzyltin(IV)]

ＩｎｔｒｏｄｕｃｔｉｏｎＤｉｏｒｇａｎｏｔｉｎｄｅｒｉｖａｔｉｖｅｓｏｆ 2 ,6 ｐｙｒｉｄｉｎｅｄｉｃａｒｂｏｘｙｌｉｃａｃｉｄｅｘｈｉｂｉｔｈｉｇｈｉｎｖｉｔｒｏａｎｔｉｔｕｍｏｕｒａｃｔｉｖｉｔｉｅｓ .1 5Ｔｈｅｓｅｃｏｍｐｏｕｎｄｓｈａｖｅｂｅｅｎｓｙｎｔｈｅｓｉｚｅｄｂｙｔｈｅｒｅａｃｔｉｏｎｏｆｄｉｏｒｇａｎｏｔｉｎｄｉｃｈｌｏｒｉｄｅｓｏｒｄｉｏｒｇａｎｏｔｉｎｏｘｉｄｅｓｗｉｔｈ 2 ,6 ｐｙｒｉｄｉｎｅｄｉｃａｒｂｏｘｙｌｉｃａｃｉｄ ,ｂｕｔｔｈｅｒｅａｃｔｉｏｎｂｅｔｗｅｅｎｔｒｉ …