A novel type of aromatic poly（ ether ether ketone） s with carboxyl groups were prepared by polycondensation of 4,4-bis（4-hydroxyphenyl）pentanoic acid with difluoro-monomers. Their mo- lecular structures were deter...A novel type of aromatic poly（ ether ether ketone） s with carboxyl groups were prepared by polycondensation of 4,4-bis（4-hydroxyphenyl）pentanoic acid with difluoro-monomers. Their mo- lecular structures were determined by ^1H-NMR and IR, respectively. Their molecular weights were measured by gel permeation chromatography （ GPC ）, which showed that all the polymers had high molecule weights （ 〉 42 000）. Due to the long side chains of polymers, all the polymers had good solubility （soluble in NMP, DMAc, THF, etc. ）. The differential scanning calorimeter （DSC） detected their excellent glass transition temperatures （ Tg ） up to 195 ℃. The Tg increased with the content of carboxylic units in the polymer chains, because the interactions of H bonds increased with increasing content of carboxylic. The polymers could form transparent and flexible films, which make them a candidate for membrane materials.展开更多
Complex [Sr2（pdc）2（H2O）7]·H2O （1, H2pdc = 2,3-pyrazinedicarboxylic acid） has been synthesized and characterized by single-crystal X-ray diffraction studies and FT-IR. Structural determination reveals that t...Complex [Sr2（pdc）2（H2O）7]·H2O （1, H2pdc = 2,3-pyrazinedicarboxylic acid） has been synthesized and characterized by single-crystal X-ray diffraction studies and FT-IR. Structural determination reveals that there are two crystallographically independent strontium ions in 1. The coordination geometry of Sr（1） is a nine-coordinated distorted monocapped tetragonal antiprism, while Sr（2） is a nine-coordinated distorted monocapped tetragonal prism. The ligand pdc2- takes two different connecting modes and links St（If） centers to generate a 2D layer structure. The 2D layers are linked through O-H...O and O-H...N hydrogen bonds to form a 3D framework structure. Thermal stability and luminescent properties of complex 1 are investigated. 1 belongs to the monoclinic system, space group P21/n with a = 10.7182（10）, b = 7.0377（6）, c = 29.225（3） A, β = 95.7170（10）°, Z = 4, V = 2193.5（3） A3, Mr = 651.56, Dc = 1.973 g/cm3, F（000） = 1296,μ = 4.951 mm-1, the final R = 0.0318 and wR = 0.0726 for 3938 observed reflections with I 〉 2σ（/）.展开更多
How to rationally design effective and practical CO_2 adsorbent is a great challenge. Herein, an ultra-microporous metal-organic framework(FJI-H19) with high concentration of free carboxyl groups and uncoordinated Lew...How to rationally design effective and practical CO_2 adsorbent is a great challenge. Herein, an ultra-microporous metal-organic framework(FJI-H19) with high concentration of free carboxyl groups and uncoordinated Lewis basic sites has been synthesized from a multi-dental ligand with a high proportion of polar CO_2-philic atoms. FJI-H19 displays a relatively high CO_2 volumetric uptake(120 cm^3?cm^(–3)) with high selectivity under practical atmosphere(298 K and 1 bar). Further researches demonstrate that such high adsorption results from an unusual synergistic effect from free carboxyl group and uncoordinated N atoms. This result will provide a potential strategy for developing more effective and pratical CO_2 adsorbent based on MOFs.展开更多
The title complex [Sm2（bdc）3（phen）2]n （1, H2bdc = 1,3-benzenedicarboxylic acid, phen = 1,10-phenanthrolin）, a new samarium（III） complex based on ligand H2bdc and 1,10-phen- anthrolin, has been hydrothermally s...The title complex [Sm2（bdc）3（phen）2]n （1, H2bdc = 1,3-benzenedicarboxylic acid, phen = 1,10-phenanthrolin）, a new samarium（III） complex based on ligand H2bdc and 1,10-phen- anthrolin, has been hydrothermally synthesized and characterized by elemental analysis, FT-IR, and single-crystal X-ray diffraction. The crystal structure reveals that the Sm（1） centre adopts an eight-coordinated distorted square anti-prism coordination geometry, while the Sm（2） centre adopts a nine-coordinated distorted monocapped square prism coordination geometry. The ligand bdc2- takes two different connecting modes and links the Sm（llI） centers to give rise to a 2D network structure. Further, 2D layers of 1 are connected together to form a 3D structure through C-H-O hydrogen bonding interactions. The luminescent property and thermal stability of complex 1 are studied. 1 belongs to the triclinic system, space group P1 with a = 10.7367（5）, b = 14.3750（7）, c = 13.7505（3）A, a = 92.8840（10）, β = 104.4010（10）, ）, = 98.1400（10）°, Z= 2, V= 2143.44（18） A3, Mr = 1153.44, Dc = 1.787 g/cm3, F（000） = 1128,μ= 2.784 mm-1, the final R = 0.0279 and wR = 0.0720 for 8226 observed reflections with 1 〉 2σ（I）.展开更多
At 225℃. caprolactone has been polymerized in the presence of succinic acid under dry nitrogen atmosphere. Characterizations of the polymer through IR and molecular weight measurements by 1H-NMR and end group titrati...At 225℃. caprolactone has been polymerized in the presence of succinic acid under dry nitrogen atmosphere. Characterizations of the polymer through IR and molecular weight measurements by 1H-NMR and end group titration have shown that the polycaprolactone obtained is of two carboxyl end groups. The molecular weight of it increases with decreasing of the acid content in the reaction mixture under the same polymerization conditions. With a certain ratio of acid to caprolactone. the maximum of molecular weight of the polymer will be reached at the reaction time of 3h.展开更多
The purpose of this experiment is to prepare a kind of large colored microspheres which can be observed under optical microscope and used for cell labelling. In the presence of organic solvent, electrolyte and dye, mi...The purpose of this experiment is to prepare a kind of large colored microspheres which can be observed under optical microscope and used for cell labelling. In the presence of organic solvent, electrolyte and dye, microspheres [styrene/acrylamide/dye (St AAm-Dye ) copolymerJ were synthesized from styrene and acrylamide by means of emulsifier-free emulsion polymerization. The carboxyl groups on the surface were derived from acrylarnide by hydrazinolysis and carboxylate reaction. The diameters of microspheres and the content of carboxyl groups on the surface were measured. The effect of the polymerization condition on microsphere size was discussed. The diam6ter of the colored microsphere was 3±0. 05μm; the content of carboxyl groups on the surface was 190. 5μmol/g (dry solids). The results indicate that it would be possible to obtain monodisperse and colored large polymer microspheres by this reported method.展开更多
The bio-mimic reactions of N-phosphoryl amino acids are very important in the study of many biochemical processes. The difference of reactivity between a-COOH and b-COOH in phosphoryl aspartic acid was studied by the...The bio-mimic reactions of N-phosphoryl amino acids are very important in the study of many biochemical processes. The difference of reactivity between a-COOH and b-COOH in phosphoryl aspartic acid was studied by theoretical study (Hartree-Fock and Density Functional methods) in this paper. The intermediates II containing five-membered ring were more stable than III with six-membered ring. While for intermediates III, the isomers with six-membered ring in apical-equatorial spanning arrangement were more stable than those with di-equatorial spanning arrangement. At B3LYP/6-31G** level, it was shown that transition states IV and V involving a-COOH or b-COOH group had energy barriers of DE = 58.67 kJmol-1 and 103.94 kJmol-1, respectively. These results were in agreement with the experimental data. So the a-COOH group was involved in form of the intramolecular penta-coordinate phosphoric-carboxylic mixed anhydride intermediates, but not b-COOH group.展开更多
Easy hydrolysis in alkaline environments limits the use of polyimide fibers in environmental protection. The hydrolysis resistance levels of polyimide fibers can be improved by crosslinking of the macromolecular chain...Easy hydrolysis in alkaline environments limits the use of polyimide fibers in environmental protection. The hydrolysis resistance levels of polyimide fibers can be improved by crosslinking of the macromolecular chains. In this work, crosslinked polyimide fibers(CPI fibers) were produced by intrinsic carboxyl decarboxylation for the first time. The thermal stability of the polyimide fibers containing the intrinsic carboxyl groups(PIC fibers) was studied, and the temperature of the decarboxylation-crosslinking reaction was determined to be 450 ℃. The PIC fibers were hotdrawn to initiate thermal crosslinking of the carboxyl groups and molecular chain orientation at high temperature. The CPI fibers had high tensile strengths(0.72-1.46 GPa) and compressive strengths(401-604 MPa). The oriented macromolecules and chemically crosslinked structure improved the tightness of the molecular chains and endowed the CPI fibers with excellent hydrolytic resistance. The CPI-50 fiber did not dissolve in a 0.5 wt% NaOH solution during heating at 90 ℃ for 10 h, and the tensile strength retention reached 87% when treated in 0.5 wt% NaOH solutions at 90 ℃ for 1 h, providing a guarantee for its application in alkaline corrosive environments.展开更多
基金Supported by Open Project of State Key Laboratory of Supramolecular Structure and Materials(SKLSSM201114)the National Natural Science Foundation of China(51103010)
文摘A novel type of aromatic poly（ ether ether ketone） s with carboxyl groups were prepared by polycondensation of 4,4-bis（4-hydroxyphenyl）pentanoic acid with difluoro-monomers. Their mo- lecular structures were determined by ^1H-NMR and IR, respectively. Their molecular weights were measured by gel permeation chromatography （ GPC ）, which showed that all the polymers had high molecule weights （ 〉 42 000）. Due to the long side chains of polymers, all the polymers had good solubility （soluble in NMP, DMAc, THF, etc. ）. The differential scanning calorimeter （DSC） detected their excellent glass transition temperatures （ Tg ） up to 195 ℃. The Tg increased with the content of carboxylic units in the polymer chains, because the interactions of H bonds increased with increasing content of carboxylic. The polymers could form transparent and flexible films, which make them a candidate for membrane materials.
基金supported by the University Science Foundation of Anhui Province(No.KJ2011Z271)Anhui Province Natural Science Foundation(No.1208085MB31)the Applied Chemistry Key Constructing Subject of Anhui Province(No.200802187C)
文摘Complex [Sr2（pdc）2（H2O）7]·H2O （1, H2pdc = 2,3-pyrazinedicarboxylic acid） has been synthesized and characterized by single-crystal X-ray diffraction studies and FT-IR. Structural determination reveals that there are two crystallographically independent strontium ions in 1. The coordination geometry of Sr（1） is a nine-coordinated distorted monocapped tetragonal antiprism, while Sr（2） is a nine-coordinated distorted monocapped tetragonal prism. The ligand pdc2- takes two different connecting modes and links St（If） centers to generate a 2D layer structure. The 2D layers are linked through O-H...O and O-H...N hydrogen bonds to form a 3D framework structure. Thermal stability and luminescent properties of complex 1 are investigated. 1 belongs to the monoclinic system, space group P21/n with a = 10.7182（10）, b = 7.0377（6）, c = 29.225（3） A, β = 95.7170（10）°, Z = 4, V = 2193.5（3） A3, Mr = 651.56, Dc = 1.973 g/cm3, F（000） = 1296,μ = 4.951 mm-1, the final R = 0.0318 and wR = 0.0726 for 3938 observed reflections with I 〉 2σ（/）.
基金supported by the National Natural Science Foundation of China(21390392,21471148)the Youth Innovation Promotion Association CAS
文摘How to rationally design effective and practical CO_2 adsorbent is a great challenge. Herein, an ultra-microporous metal-organic framework(FJI-H19) with high concentration of free carboxyl groups and uncoordinated Lewis basic sites has been synthesized from a multi-dental ligand with a high proportion of polar CO_2-philic atoms. FJI-H19 displays a relatively high CO_2 volumetric uptake(120 cm^3?cm^(–3)) with high selectivity under practical atmosphere(298 K and 1 bar). Further researches demonstrate that such high adsorption results from an unusual synergistic effect from free carboxyl group and uncoordinated N atoms. This result will provide a potential strategy for developing more effective and pratical CO_2 adsorbent based on MOFs.
基金supported by the Natural Science Foundation of Anhui Province(1208085MB31)NNSFC(21271106)+1 种基金the Applied Chemistry Key Constructing Subject of Anhui Province(200802187C)Student Research Project of Chuzhou University(2012XS18,2012XS19)
文摘The title complex [Sm2（bdc）3（phen）2]n （1, H2bdc = 1,3-benzenedicarboxylic acid, phen = 1,10-phenanthrolin）, a new samarium（III） complex based on ligand H2bdc and 1,10-phen- anthrolin, has been hydrothermally synthesized and characterized by elemental analysis, FT-IR, and single-crystal X-ray diffraction. The crystal structure reveals that the Sm（1） centre adopts an eight-coordinated distorted square anti-prism coordination geometry, while the Sm（2） centre adopts a nine-coordinated distorted monocapped square prism coordination geometry. The ligand bdc2- takes two different connecting modes and links the Sm（llI） centers to give rise to a 2D network structure. Further, 2D layers of 1 are connected together to form a 3D structure through C-H-O hydrogen bonding interactions. The luminescent property and thermal stability of complex 1 are studied. 1 belongs to the triclinic system, space group P1 with a = 10.7367（5）, b = 14.3750（7）, c = 13.7505（3）A, a = 92.8840（10）, β = 104.4010（10）, ）, = 98.1400（10）°, Z= 2, V= 2143.44（18） A3, Mr = 1153.44, Dc = 1.787 g/cm3, F（000） = 1128,μ= 2.784 mm-1, the final R = 0.0279 and wR = 0.0720 for 8226 observed reflections with 1 〉 2σ（I）.
文摘At 225℃. caprolactone has been polymerized in the presence of succinic acid under dry nitrogen atmosphere. Characterizations of the polymer through IR and molecular weight measurements by 1H-NMR and end group titration have shown that the polycaprolactone obtained is of two carboxyl end groups. The molecular weight of it increases with decreasing of the acid content in the reaction mixture under the same polymerization conditions. With a certain ratio of acid to caprolactone. the maximum of molecular weight of the polymer will be reached at the reaction time of 3h.
文摘The purpose of this experiment is to prepare a kind of large colored microspheres which can be observed under optical microscope and used for cell labelling. In the presence of organic solvent, electrolyte and dye, microspheres [styrene/acrylamide/dye (St AAm-Dye ) copolymerJ were synthesized from styrene and acrylamide by means of emulsifier-free emulsion polymerization. The carboxyl groups on the surface were derived from acrylarnide by hydrazinolysis and carboxylate reaction. The diameters of microspheres and the content of carboxyl groups on the surface were measured. The effect of the polymerization condition on microsphere size was discussed. The diam6ter of the colored microsphere was 3±0. 05μm; the content of carboxyl groups on the surface was 190. 5μmol/g (dry solids). The results indicate that it would be possible to obtain monodisperse and colored large polymer microspheres by this reported method.
基金the National Natural Science Foundation of China (No. 29802006) the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institutions of MOE P.R.C. and Tsinghua University.
文摘The bio-mimic reactions of N-phosphoryl amino acids are very important in the study of many biochemical processes. The difference of reactivity between a-COOH and b-COOH in phosphoryl aspartic acid was studied by theoretical study (Hartree-Fock and Density Functional methods) in this paper. The intermediates II containing five-membered ring were more stable than III with six-membered ring. While for intermediates III, the isomers with six-membered ring in apical-equatorial spanning arrangement were more stable than those with di-equatorial spanning arrangement. At B3LYP/6-31G** level, it was shown that transition states IV and V involving a-COOH or b-COOH group had energy barriers of DE = 58.67 kJmol-1 and 103.94 kJmol-1, respectively. These results were in agreement with the experimental data. So the a-COOH group was involved in form of the intramolecular penta-coordinate phosphoric-carboxylic mixed anhydride intermediates, but not b-COOH group.
基金financially supported by the Scientific Research Innovation Plan of Shanghai Education Commission (No. 2019-01-07-00-03-E00001)the National Natural Science Foundation of China (Nos. U21A2087 and 21975040)the Natural Science Foundation of Shanghai (No. 21ZR1400200)。
文摘Easy hydrolysis in alkaline environments limits the use of polyimide fibers in environmental protection. The hydrolysis resistance levels of polyimide fibers can be improved by crosslinking of the macromolecular chains. In this work, crosslinked polyimide fibers(CPI fibers) were produced by intrinsic carboxyl decarboxylation for the first time. The thermal stability of the polyimide fibers containing the intrinsic carboxyl groups(PIC fibers) was studied, and the temperature of the decarboxylation-crosslinking reaction was determined to be 450 ℃. The PIC fibers were hotdrawn to initiate thermal crosslinking of the carboxyl groups and molecular chain orientation at high temperature. The CPI fibers had high tensile strengths(0.72-1.46 GPa) and compressive strengths(401-604 MPa). The oriented macromolecules and chemically crosslinked structure improved the tightness of the molecular chains and endowed the CPI fibers with excellent hydrolytic resistance. The CPI-50 fiber did not dissolve in a 0.5 wt% NaOH solution during heating at 90 ℃ for 10 h, and the tensile strength retention reached 87% when treated in 0.5 wt% NaOH solutions at 90 ℃ for 1 h, providing a guarantee for its application in alkaline corrosive environments.
