The title complex 1,{[CuEu（Hbidc）2（H2O）4]·H2O}n（H3bidc = 1H-benzimidazole-5,6-dicarboxylic acid）,has been solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction.Comple...The title complex 1,{[CuEu（Hbidc）2（H2O）4]·H2O}n（H3bidc = 1H-benzimidazole-5,6-dicarboxylic acid）,has been solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction.Complex 1 crystallizes in triclinic,space group P1,with a = 7.791（2）,b = 12.058（3）,c = 12.109（3）,α = 82.189（5）,β = 72.407（5）,γ = 89.184（4）°,V = 1073.7（5）3,C18H18CuEuN4O13,Mr = 713.86,Dc = 2.208 g/cm3,μ（MoKα） = 3.967 mm-1,F（000） = 700,GOOF = 0.950,Z = 2,the final R = 0.0531 and wR = 0.1068 for I 2σ（I）.Complex 1 possess a tape-like chain structure consisting of Eu2C8O4 and Cu2Eu2C18N4O4 metallic rings alternatively arranged and is the first 3d-4f heterometallic complex based on the 1H-ben-zimidazole-5,6-dicarboxylato ligand（Hbidc）.Plenty of hydrogen-bonding and π...π stacking interactions connect the 1D chains to construct a 3D supramolecular architecture.展开更多
Two novel ligands named 4-styrylpyridine-2,6-dicarboxylic acid (4-SPDA) and 4-(4-(2-(2, 6-dicarboxypyridin-4-yl)- vinyl)styryl)pyridine-2,6-dicarboxylic acid(DSPDA) and their complexes with Tb(Ⅲ) were synthesized and...Two novel ligands named 4-styrylpyridine-2,6-dicarboxylic acid (4-SPDA) and 4-(4-(2-(2, 6-dicarboxypyridin-4-yl)- vinyl)styryl)pyridine-2,6-dicarboxylic acid(DSPDA) and their complexes with Tb(Ⅲ) were synthesized and characterized by infrared spectrometry, 1H nuclear magnetic resonance, elemental analysis and gas chromatograph-mass spectrometry. The ligand synthetic route was optimized. The fluorescence properties of the complex in solid state, in different kind of solvents and in solutions with different pH values were investigated in detail. The results show that the yields of DSPDA and 4-SPDA reach over 78% by Wittig-Horner reaction and other eight pyridine-2, 6-dicarboxylic acid derivatives with different substituents on pyridine ring, and their complexes with Tb(Ⅲ) are also obtained. The fluorescence intensities of the complexes with electron-donating groups are more intense than those of the complexes with electron-withdrawing groups on pyridine ring; fluorescence intensities of the complexes are the strongest in neutral solution (pH=7), and the less the dipole moment of solvent molecule is, the stronger the fluorescence intensity is. It is found that the two ligands (4-APDA and DSPDA) are the good sensitizers for Tb(Ⅲ) ion.展开更多
A polynuclear complex [Cd（endc）（H20）]n·nH2O （endc = endo-norbornene-cis- 5,6-dicarboxylate anion） has been synthesized by the hydrothermal reaction of cadmium nitrate tetrahydrate with endo-norbornene-cis-5...A polynuclear complex [Cd（endc）（H20）]n·nH2O （endc = endo-norbornene-cis- 5,6-dicarboxylate anion） has been synthesized by the hydrothermal reaction of cadmium nitrate tetrahydrate with endo-norbornene-cis-5,6-dicarboxylic acid in 1：1 molar ratio, and structurally characterized by single-crystal X-ray diffraction. It crystallizes in monoclinic, space group P21/c with α = 1.16471（7）, b = 0.95334（7）, c = 0.91109（9） nm, Z= 4, V= 1.01035（14） nm^3, D, = 2.160 g/cm^3,μ = 2.172 mm^-1, F（000） = 648, R = 0.0302 and wR = 0.0752. According to structural analysis, each Cd（II） ion is coordinated to six O atoms from three endc anions and one water molecule, giving a distorted octahedral geometry. Two- dimensional layer arrangement of the title complex is constructed from the bridging nature of endc. It is worth notice that adjacent two-dimensional layers are joined together to form a three-dimensional supramolecular framework via intermolecular hydrogen bonding interactions.展开更多
This paper reports that the low-temperature heat capacities of pyridine-2,6-dicarboxylic acid were measured by a precision automatic calorimeter over a temperature range from 78 K to 380 K. A polynomial equation of he...This paper reports that the low-temperature heat capacities of pyridine-2,6-dicarboxylic acid were measured by a precision automatic calorimeter over a temperature range from 78 K to 380 K. A polynomial equation of heat capacities as a function of temperature was fitted by the least-squares method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at intervals of 5 K. The constant-volume energy of combustion of the compound was determined by means of a precision rotating-bomb combustion calorimeter. The standard molar enthalpy of combustion of the compound was derived from the constant-volume energy of combustion. The standard molar enthalpy of formation of the compound was calculated from a combination of the datum of the standard molar enthalpy of combustion of the compound with other auxiliary thermodynamic quantities through a Hess thermochemical cycle.展开更多
This research took 2,6-dimethylpyridine as raw materials under microwave irradiation to syntheses pyridine 2,6-dicarboxylic acid by adding oxidation potassium permanganate. However, there are lots of factors affecting...This research took 2,6-dimethylpyridine as raw materials under microwave irradiation to syntheses pyridine 2,6-dicarboxylic acid by adding oxidation potassium permanganate. However, there are lots of factors affecting the yield including the amount of potassium permanganate and sulfuric acid, reaction time, power, 2,6-dimethylpyridine dosage. We made the further research, using orthogonal experiment to find the optimal process conditions. Thus our research changed the synthesis process from a traditional method to a new type of microwave technology.展开更多
Various 4-alkoxypyridine-2, 6-dicarboxylic acids were synthesized starting from 2, 6- lutidine. Through aldol condensation and Michael addition, various 4-arylpyridine-2, 6-dicarboxylic acids were synthesized starting...Various 4-alkoxypyridine-2, 6-dicarboxylic acids were synthesized starting from 2, 6- lutidine. Through aldol condensation and Michael addition, various 4-arylpyridine-2, 6-dicarboxylic acids were synthesized starting from aromatic aldehydes and 2-acetylfuran.展开更多
Two lanthanide coordination polymers, {[Ln（Hbidc）（bidc）（H2 O）3]·3 H2 O}n（H3 bidc = benzimidazole-5,6-dicarboxylic acid, Ln = Eu（1）, Sm（2）） have been hydrothermally synthesized. Both compounds are isos...Two lanthanide coordination polymers, {[Ln（Hbidc）（bidc）（H2 O）3]·3 H2 O}n（H3 bidc = benzimidazole-5,6-dicarboxylic acid, Ln = Eu（1）, Sm（2）） have been hydrothermally synthesized. Both compounds are isostructure and crystallize in the P21/c space group of monoclinic system. Complex 1: a = 11.087（6）, b = 8.972（5）, c = 23.064（13） ?, b = 95.027（5）o, V = 2285.4（2） ?3, Z = 4, Mr = 669.35, Dc = 1.945 g/cm3, F（000） = 1328, S = 1.044, μ = 2.827 mm-1, R = 0.0393 and wR = 0.0801 for 3458 observed reflections（I > 2s（I））. Complex 2: a = 11.087（6）, b = 8.972（5）, c = 23.064（13） ?, b = 95.027（5）°, V = 2285.4（2） ?3, Z = 4, Mr = 667.74, Dc = 1.941 g/cm3, F（000） = 1324, S = 1.071, μ = 2.652 mm-1, R = 0.0329 and wR = 0.0809 for 3744 observed reflections（I > 2s（I））. Complexes 1 and 2 have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectroscopy, and thermogravimetric analyses（TGA）. The single-crystal X-ray diffraction analysis reveals that complexes 1 and 2 are the isostructural 1 D zigzag chain structures, which are further extended into a 3 D supramolecular structure through hydrogen bonds and p···p stacking interactions. Furthermore, the thermal stability, UV-vis absorption spectra and fluorescent properties of complexes 1 and 2 have been investigated and discussed in detail.展开更多
Some spectral properties and luminescence intensities of Tb 3+ chelates of substituted pyridine 2, 6 dicarboxylic acids and 4 phenyl pyridine 2, 6 dicarboxylic acid analogues were measured in some solutions...Some spectral properties and luminescence intensities of Tb 3+ chelates of substituted pyridine 2, 6 dicarboxylic acids and 4 phenyl pyridine 2, 6 dicarboxylic acid analogues were measured in some solutions (H 2O and EtOH etc.) by synergistic effect of EDTA. The substitution at the aromatic ring has a significant effect upon the observed luminescence intensities, excitation wavelengths, and lifetime of the complexes. Moreover, the changes in the environment cause great variation in those properties of certain Tb 3+ chelates. The results show that some of hte chelates (4 acetaminopoxypyridine 2, 6 dicarboxylic acid, 4 ethoxypyridine 2, 6 dicarboxylic acid and 4 methoxypyridine 2, 6 dicarboxylic acid etc.) have a stronger emission and longer lifetime at room temperature and may thus be used as perfectly sensitizers in fluorescence analysis.展开更多
Recently,azobenzene-4,4'-dicarboxylic acid(ADCA)has been produced gradually for use as an organic synthesis or pharmaceutical intermediate due to its eminent performance.With large quantities put into application ...Recently,azobenzene-4,4'-dicarboxylic acid(ADCA)has been produced gradually for use as an organic synthesis or pharmaceutical intermediate due to its eminent performance.With large quantities put into application in the future,the thermal stability of this substance during storage,transportation,and use will become quite important.Thus,in this work,the thermal decomposition behavior,thermal decomposition kinetics,and thermal hazard of ADCA were investigated.Experiments were conducted by using a SENSYS evo DSC device.A combination of differential iso-conversion method,compensation parameter method,and nonlinear fitting evaluation were also used to analyze thermal kinetics and mechanism of ADCA decomposition.The results show that when conversion rate α increases,the activation energies of ADCA's first and main decomposition peaks fall.The amount of heat released during decomposition varies between 182.46 and 231.16 J·g^(-1).The proposed kinetic equation is based on the Avrami-Erofeev model,which is consistent with the decomposition progress.Applying the Frank-Kamenetskii model,a calculated self-accelerating decomposition temperature of 287.0℃is obtained.展开更多
基金Supported by the Nanjing University of Posts and Telecommunications(No.NY209032)the National Natural Science Foundation of China(No.21001065)the Major State Basic Research Development Program of China (973 Program,No.2009CB930600)
文摘The title complex 1,{[CuEu（Hbidc）2（H2O）4]·H2O}n（H3bidc = 1H-benzimidazole-5,6-dicarboxylic acid）,has been solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction.Complex 1 crystallizes in triclinic,space group P1,with a = 7.791（2）,b = 12.058（3）,c = 12.109（3）,α = 82.189（5）,β = 72.407（5）,γ = 89.184（4）°,V = 1073.7（5）3,C18H18CuEuN4O13,Mr = 713.86,Dc = 2.208 g/cm3,μ（MoKα） = 3.967 mm-1,F（000） = 700,GOOF = 0.950,Z = 2,the final R = 0.0531 and wR = 0.1068 for I 2σ（I）.Complex 1 possess a tape-like chain structure consisting of Eu2C8O4 and Cu2Eu2C18N4O4 metallic rings alternatively arranged and is the first 3d-4f heterometallic complex based on the 1H-ben-zimidazole-5,6-dicarboxylato ligand（Hbidc）.Plenty of hydrogen-bonding and π...π stacking interactions connect the 1D chains to construct a 3D supramolecular architecture.
基金Project(20761002) supported by the National Natural Science Foundation of China
文摘Two novel ligands named 4-styrylpyridine-2,6-dicarboxylic acid (4-SPDA) and 4-(4-(2-(2, 6-dicarboxypyridin-4-yl)- vinyl)styryl)pyridine-2,6-dicarboxylic acid(DSPDA) and their complexes with Tb(Ⅲ) were synthesized and characterized by infrared spectrometry, 1H nuclear magnetic resonance, elemental analysis and gas chromatograph-mass spectrometry. The ligand synthetic route was optimized. The fluorescence properties of the complex in solid state, in different kind of solvents and in solutions with different pH values were investigated in detail. The results show that the yields of DSPDA and 4-SPDA reach over 78% by Wittig-Horner reaction and other eight pyridine-2, 6-dicarboxylic acid derivatives with different substituents on pyridine ring, and their complexes with Tb(Ⅲ) are also obtained. The fluorescence intensities of the complexes with electron-donating groups are more intense than those of the complexes with electron-withdrawing groups on pyridine ring; fluorescence intensities of the complexes are the strongest in neutral solution (pH=7), and the less the dipole moment of solvent molecule is, the stronger the fluorescence intensity is. It is found that the two ligands (4-APDA and DSPDA) are the good sensitizers for Tb(Ⅲ) ion.
基金This work was supported by the National Natural Science Foundation of China (No. 20571057)
文摘A polynuclear complex [Cd（endc）（H20）]n·nH2O （endc = endo-norbornene-cis- 5,6-dicarboxylate anion） has been synthesized by the hydrothermal reaction of cadmium nitrate tetrahydrate with endo-norbornene-cis-5,6-dicarboxylic acid in 1：1 molar ratio, and structurally characterized by single-crystal X-ray diffraction. It crystallizes in monoclinic, space group P21/c with α = 1.16471（7）, b = 0.95334（7）, c = 0.91109（9） nm, Z= 4, V= 1.01035（14） nm^3, D, = 2.160 g/cm^3,μ = 2.172 mm^-1, F（000） = 648, R = 0.0302 and wR = 0.0752. According to structural analysis, each Cd（II） ion is coordinated to six O atoms from three endc anions and one water molecule, giving a distorted octahedral geometry. Two- dimensional layer arrangement of the title complex is constructed from the bridging nature of endc. It is worth notice that adjacent two-dimensional layers are joined together to form a three-dimensional supramolecular framework via intermolecular hydrogen bonding interactions.
基金Project supported by the National Natural Science Foundations of China (Grant Nos.20673050 and 20973089)
文摘This paper reports that the low-temperature heat capacities of pyridine-2,6-dicarboxylic acid were measured by a precision automatic calorimeter over a temperature range from 78 K to 380 K. A polynomial equation of heat capacities as a function of temperature was fitted by the least-squares method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at intervals of 5 K. The constant-volume energy of combustion of the compound was determined by means of a precision rotating-bomb combustion calorimeter. The standard molar enthalpy of combustion of the compound was derived from the constant-volume energy of combustion. The standard molar enthalpy of formation of the compound was calculated from a combination of the datum of the standard molar enthalpy of combustion of the compound with other auxiliary thermodynamic quantities through a Hess thermochemical cycle.
文摘This research took 2,6-dimethylpyridine as raw materials under microwave irradiation to syntheses pyridine 2,6-dicarboxylic acid by adding oxidation potassium permanganate. However, there are lots of factors affecting the yield including the amount of potassium permanganate and sulfuric acid, reaction time, power, 2,6-dimethylpyridine dosage. We made the further research, using orthogonal experiment to find the optimal process conditions. Thus our research changed the synthesis process from a traditional method to a new type of microwave technology.
文摘Various 4-alkoxypyridine-2, 6-dicarboxylic acids were synthesized starting from 2, 6- lutidine. Through aldol condensation and Michael addition, various 4-arylpyridine-2, 6-dicarboxylic acids were synthesized starting from aromatic aldehydes and 2-acetylfuran.
基金supported by the Key Basic Research Project of Hebei Province(18961031D)the High-Level Talents Funding Project of Hebei Province(A201400233)+2 种基金the Science and Technology Research Project of Hebei’s Colleges and University(No.BJ 2017035)the Science and Technology Research and Development Program of Hebei Province,Zhangjiakou City(17120011D)the Doctoral Foundation of Hebei North University(12995557)
文摘Two lanthanide coordination polymers, {[Ln（Hbidc）（bidc）（H2 O）3]·3 H2 O}n（H3 bidc = benzimidazole-5,6-dicarboxylic acid, Ln = Eu（1）, Sm（2）） have been hydrothermally synthesized. Both compounds are isostructure and crystallize in the P21/c space group of monoclinic system. Complex 1: a = 11.087（6）, b = 8.972（5）, c = 23.064（13） ?, b = 95.027（5）o, V = 2285.4（2） ?3, Z = 4, Mr = 669.35, Dc = 1.945 g/cm3, F（000） = 1328, S = 1.044, μ = 2.827 mm-1, R = 0.0393 and wR = 0.0801 for 3458 observed reflections（I > 2s（I））. Complex 2: a = 11.087（6）, b = 8.972（5）, c = 23.064（13） ?, b = 95.027（5）°, V = 2285.4（2） ?3, Z = 4, Mr = 667.74, Dc = 1.941 g/cm3, F（000） = 1324, S = 1.071, μ = 2.652 mm-1, R = 0.0329 and wR = 0.0809 for 3744 observed reflections（I > 2s（I））. Complexes 1 and 2 have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectroscopy, and thermogravimetric analyses（TGA）. The single-crystal X-ray diffraction analysis reveals that complexes 1 and 2 are the isostructural 1 D zigzag chain structures, which are further extended into a 3 D supramolecular structure through hydrogen bonds and p···p stacking interactions. Furthermore, the thermal stability, UV-vis absorption spectra and fluorescent properties of complexes 1 and 2 have been investigated and discussed in detail.
文摘Some spectral properties and luminescence intensities of Tb 3+ chelates of substituted pyridine 2, 6 dicarboxylic acids and 4 phenyl pyridine 2, 6 dicarboxylic acid analogues were measured in some solutions (H 2O and EtOH etc.) by synergistic effect of EDTA. The substitution at the aromatic ring has a significant effect upon the observed luminescence intensities, excitation wavelengths, and lifetime of the complexes. Moreover, the changes in the environment cause great variation in those properties of certain Tb 3+ chelates. The results show that some of hte chelates (4 acetaminopoxypyridine 2, 6 dicarboxylic acid, 4 ethoxypyridine 2, 6 dicarboxylic acid and 4 methoxypyridine 2, 6 dicarboxylic acid etc.) have a stronger emission and longer lifetime at room temperature and may thus be used as perfectly sensitizers in fluorescence analysis.
基金supported by National Natural Science Foundation of China(51974166).
文摘Recently,azobenzene-4,4'-dicarboxylic acid(ADCA)has been produced gradually for use as an organic synthesis or pharmaceutical intermediate due to its eminent performance.With large quantities put into application in the future,the thermal stability of this substance during storage,transportation,and use will become quite important.Thus,in this work,the thermal decomposition behavior,thermal decomposition kinetics,and thermal hazard of ADCA were investigated.Experiments were conducted by using a SENSYS evo DSC device.A combination of differential iso-conversion method,compensation parameter method,and nonlinear fitting evaluation were also used to analyze thermal kinetics and mechanism of ADCA decomposition.The results show that when conversion rate α increases,the activation energies of ADCA's first and main decomposition peaks fall.The amount of heat released during decomposition varies between 182.46 and 231.16 J·g^(-1).The proposed kinetic equation is based on the Avrami-Erofeev model,which is consistent with the decomposition progress.Applying the Frank-Kamenetskii model,a calculated self-accelerating decomposition temperature of 287.0℃is obtained.
