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2014 Volume 25 Issue 6
2014, 25(6): 823-828
doi: 10.1016/j.cclet.2014.04.032
Abstract:
Reaction temperature is one of the key parameters in the synthesis ofmetal-organic frameworks (MOFs). Though there is no convergence with regard to the various experimental parameters, reaction temperature has been found to have remarkable influence on the formation and structure of MOFs, especially toward the control of topology and dimensionality of the MOF structures. Theoretically, the reaction temperature affects directly the reaction energy barrier in reaction thermodynamics and the reaction rate in the reaction kinetics. This review aims to show the influence of reaction temperature on crystal growth/assembly, structural modulation and transformation of MOFs, and to provide primary information and insights into the design and assembly of desired MOFs.
Reaction temperature is one of the key parameters in the synthesis ofmetal-organic frameworks (MOFs). Though there is no convergence with regard to the various experimental parameters, reaction temperature has been found to have remarkable influence on the formation and structure of MOFs, especially toward the control of topology and dimensionality of the MOF structures. Theoretically, the reaction temperature affects directly the reaction energy barrier in reaction thermodynamics and the reaction rate in the reaction kinetics. This review aims to show the influence of reaction temperature on crystal growth/assembly, structural modulation and transformation of MOFs, and to provide primary information and insights into the design and assembly of desired MOFs.
2014, 25(6): 829-834
doi: 10.1016/j.cclet.2014.05.025
Abstract:
Two 3d-4f heterometallic one-dimensional chains with neutral 4,4'-bipyridine ligands as linkers and [Cu2Ln2] clusters (Ln=Gd for 1, Dy for 2) as nodes have been hydrothermally synthesized and structurally characterized. Magnetic studies indicate that complex 1 exhibits a relatively large magnetocaloric effect, with an entropy change -△Smmax=24:8 J kg-1 K-1, whilst, complex 2 features slow magnetic relaxation at low temperature.
Two 3d-4f heterometallic one-dimensional chains with neutral 4,4'-bipyridine ligands as linkers and [Cu2Ln2] clusters (Ln=Gd for 1, Dy for 2) as nodes have been hydrothermally synthesized and structurally characterized. Magnetic studies indicate that complex 1 exhibits a relatively large magnetocaloric effect, with an entropy change -△Smmax=24:8 J kg-1 K-1, whilst, complex 2 features slow magnetic relaxation at low temperature.
2014, 25(6): 835-838
doi: 10.1016/j.cclet.2014.05.005
Abstract:
Two new mixed-ligated metal phosphonates, M2(pbtcH)(phen)2(H2O)2 [M(II)=Co (1), Ni (2)] (pbtcH5=5-phosphonatophenyl-1,2,4-tricarboxylic acid, phen=1,1'-phenanthroline), have been synthesized and characterized. Both show one-dimensional double chain structures, where the M(phen)(H2O) moieties are chelated and bridged by pbtcH4- through the carboxylate and phosphonate oxygen atoms. The chains are connected by hydrogen bonding interactions and π-π stacking, forming a three-dimensional supramolecular structure. The IR and magnetic properties of the two compounds are also investigated.
Two new mixed-ligated metal phosphonates, M2(pbtcH)(phen)2(H2O)2 [M(II)=Co (1), Ni (2)] (pbtcH5=5-phosphonatophenyl-1,2,4-tricarboxylic acid, phen=1,1'-phenanthroline), have been synthesized and characterized. Both show one-dimensional double chain structures, where the M(phen)(H2O) moieties are chelated and bridged by pbtcH4- through the carboxylate and phosphonate oxygen atoms. The chains are connected by hydrogen bonding interactions and π-π stacking, forming a three-dimensional supramolecular structure. The IR and magnetic properties of the two compounds are also investigated.
2014, 25(6): 839-843
doi: 10.1016/j.cclet.2014.05.027
Abstract:
The stabilities of [M12Ag32(SR)30]4- (M=Ag, Au and SR=SPhF2, SPhCF3, SPhF) clusters having the same structure but different surface ligands or counter cations were systematically studied. It was clearly revealed that a subtle structural change in the surface ligands or counter cations could significantly alter the overall stability of [M12Ag32(SR)30]4- although they all had an electronic structure of 18-electron superatom shell closure. SPhCF2 was found as a better surface ligand than SPhCF3 or SPhF to stabilize [M12Ag32(SR)30]4-. And the use of more bulky [(PPh3)2N]+ as the counter cations was revealed to bemore deleterious to the overall stability of [M12Ag32(SR)30]4- clusters than PPh4+. [Au12Ag32(SR)30]4- was muchmore stable than [Ag44(SR)30]4- with the same surface ligands and counter cations. An exceptional stability was observed on (PPh4)4[Au12Ag32(SPhCF2)30] which was stable in DMF for more than 8 days in air at 80℃. More research efforts are still needed to deeply understand why a small structural change could result in a significant change in the stability of noble metal nanoclusters.
The stabilities of [M12Ag32(SR)30]4- (M=Ag, Au and SR=SPhF2, SPhCF3, SPhF) clusters having the same structure but different surface ligands or counter cations were systematically studied. It was clearly revealed that a subtle structural change in the surface ligands or counter cations could significantly alter the overall stability of [M12Ag32(SR)30]4- although they all had an electronic structure of 18-electron superatom shell closure. SPhCF2 was found as a better surface ligand than SPhCF3 or SPhF to stabilize [M12Ag32(SR)30]4-. And the use of more bulky [(PPh3)2N]+ as the counter cations was revealed to bemore deleterious to the overall stability of [M12Ag32(SR)30]4- clusters than PPh4+. [Au12Ag32(SR)30]4- was muchmore stable than [Ag44(SR)30]4- with the same surface ligands and counter cations. An exceptional stability was observed on (PPh4)4[Au12Ag32(SPhCF2)30] which was stable in DMF for more than 8 days in air at 80℃. More research efforts are still needed to deeply understand why a small structural change could result in a significant change in the stability of noble metal nanoclusters.
2014, 25(6): 844-848
doi: 10.1016/j.cclet.2014.05.028
Abstract:
The title compound, tetramethylammonium nickel nitrite [(CH3)4N][Ni(NO2)3], has a hexagonal perovskite-type structure with formula ABX3. It undergoes two reversible phase transitions occurring at about 409.1 and 428.4 K, associated with dielectric transitions. DSC measurement and dielectric measurement confirm the transition. The variable-temperature X-ray structural determinations and the powder X-ray diffraction (PXRD) experiments reveal that this compound has the same space group P3m1 (No. 164) at 293 K, 413 K and 438 K. The phase transitions are caused by the rotation of the [(CH3)4N]+ cation.
The title compound, tetramethylammonium nickel nitrite [(CH3)4N][Ni(NO2)3], has a hexagonal perovskite-type structure with formula ABX3. It undergoes two reversible phase transitions occurring at about 409.1 and 428.4 K, associated with dielectric transitions. DSC measurement and dielectric measurement confirm the transition. The variable-temperature X-ray structural determinations and the powder X-ray diffraction (PXRD) experiments reveal that this compound has the same space group P3m1 (No. 164) at 293 K, 413 K and 438 K. The phase transitions are caused by the rotation of the [(CH3)4N]+ cation.
2014, 25(6): 849-853
doi: 10.1016/j.cclet.2014.03.031
Abstract:
PbTe/SnTe hybrid nanocrystals with designed shape, chemical composition and narrow size distribution were synthesized by an efficient solvothermal approach. This approach enables mass and economical synthesis of PbTe-based nanocrystals. The organic ligands were completely removed by pretreatment with a super-hydride solution, making it possible to fabricate fully dense and robust thermoelectric devices with increased electrical conductivity.
PbTe/SnTe hybrid nanocrystals with designed shape, chemical composition and narrow size distribution were synthesized by an efficient solvothermal approach. This approach enables mass and economical synthesis of PbTe-based nanocrystals. The organic ligands were completely removed by pretreatment with a super-hydride solution, making it possible to fabricate fully dense and robust thermoelectric devices with increased electrical conductivity.
2014, 25(6): 854-858
doi: 10.1016/j.cclet.2014.05.026
Abstract:
A coordination polymer formulated as {[Mn2L(N3)4]•2H2O}n(1) [L=1,4-bis(pyridinil-3-carboxylato)-l,4-dimethylbenzene] was synthesized and structurally and magnetically characterized. The uniform Mn(II) chains withmixed (μ-EO-N3)2(μ-COO) triple bridges (EO=end-on) are linked by L ligands to generate a 2-fold interpenetrating 3D framework. Meanwhile, magnetism analysis reveals antiferromagnetic coupling for 1.
A coordination polymer formulated as {[Mn2L(N3)4]•2H2O}n(1) [L=1,4-bis(pyridinil-3-carboxylato)-l,4-dimethylbenzene] was synthesized and structurally and magnetically characterized. The uniform Mn(II) chains withmixed (μ-EO-N3)2(μ-COO) triple bridges (EO=end-on) are linked by L ligands to generate a 2-fold interpenetrating 3D framework. Meanwhile, magnetism analysis reveals antiferromagnetic coupling for 1.
2014, 25(6): 859-864
doi: 10.1016/j.cclet.2014.04.010
Abstract:
Ionic liquid gel polymers have widely been used as the electrolytes in all-solid-state supercapacitors, but they suffer from low ionic conductivity and poor electrochemical performance. Arc discharge is a fast, low-cost and scalable method to prepare multi-layered graphene nanosheets, and as-made graphene nanosheets (denoted as ad-GNSs) with few defects, high electrical conductivity and high thermal stability should be favorable conductive additive materials. Here, a novel ionic liquid gel polymer electrolyte based on an ionic liquid (EMIMNTF2) and an copolymer (P(VDF-HFP)) was modified by the addition of ad-GNSs as an ionic conducting promoter. This modified gel electrolyte shows excellent thermal stability up to 400℃ and a wide electrochemical window of 3 V. An all-solid-state supercapacitor based on commercial activated carbon was fabricated using this modified ionic liquid gel polymer electrolyte, which shows obviously improved electrochemical behaviors compared with those of the corresponding all-solid-state supercapacitor using pure ionic liquid gel polymer electrolyte. Specially, smaller internal resistance, higher specific capacitance, better rate performance and cycling stability are achieved. These results indicate that the ionic liquid gel polymers modified by ad-GNSs would be promising and suitable gel electrolytes for high performance all-solid-state electrochemical devices.
Ionic liquid gel polymers have widely been used as the electrolytes in all-solid-state supercapacitors, but they suffer from low ionic conductivity and poor electrochemical performance. Arc discharge is a fast, low-cost and scalable method to prepare multi-layered graphene nanosheets, and as-made graphene nanosheets (denoted as ad-GNSs) with few defects, high electrical conductivity and high thermal stability should be favorable conductive additive materials. Here, a novel ionic liquid gel polymer electrolyte based on an ionic liquid (EMIMNTF2) and an copolymer (P(VDF-HFP)) was modified by the addition of ad-GNSs as an ionic conducting promoter. This modified gel electrolyte shows excellent thermal stability up to 400℃ and a wide electrochemical window of 3 V. An all-solid-state supercapacitor based on commercial activated carbon was fabricated using this modified ionic liquid gel polymer electrolyte, which shows obviously improved electrochemical behaviors compared with those of the corresponding all-solid-state supercapacitor using pure ionic liquid gel polymer electrolyte. Specially, smaller internal resistance, higher specific capacitance, better rate performance and cycling stability are achieved. These results indicate that the ionic liquid gel polymers modified by ad-GNSs would be promising and suitable gel electrolytes for high performance all-solid-state electrochemical devices.
2014, 25(6): 865-868
doi: 10.1016/j.cclet.2014.05.004
Abstract:
High-performance supercapacitor electrode materials are prepared from the commercially available activated carbon (AC) through a facile and low-cost chemical activation method. The obtained results show that AC activated by KOH with an alkali/carbon ratio of 6/1 (ACK6) possesses a specific surface area of 3405 m2/g, a large pore volume of 2.01 cm3/g, and exhibits the highest initial specific capacitance of 335 F/g at the current density of 0.5 A/g in 6 mol/L KOH, and 85% coloumbic efficiency for 5000 cycles at 20 mV/s.
High-performance supercapacitor electrode materials are prepared from the commercially available activated carbon (AC) through a facile and low-cost chemical activation method. The obtained results show that AC activated by KOH with an alkali/carbon ratio of 6/1 (ACK6) possesses a specific surface area of 3405 m2/g, a large pore volume of 2.01 cm3/g, and exhibits the highest initial specific capacitance of 335 F/g at the current density of 0.5 A/g in 6 mol/L KOH, and 85% coloumbic efficiency for 5000 cycles at 20 mV/s.
2014, 25(6): 869-873
doi: 10.1016/j.cclet.2014.04.030
Abstract:
Mesoporous single crystal-like Y2O3 nanocubes have been prepared through a coordination-based selfassembly process. Firstly, a uniform nanocube-like Y-lysine precursor was simply prepared with hydrothermal treatment. After the simple thermal treatment process, nanocube-shaped yttrium oxides with the morphology inherited from the Y-lysine precursor were successfully prepared. The phase, morphology, size and crystalline structure were well characterized by XRD, SEM and TEM. N2 adsorption-desorption demonstrates the mesoporous characteristics of the Y2O3 nanocubes, showing a relatively high surface area of 60 m2/g.
Mesoporous single crystal-like Y2O3 nanocubes have been prepared through a coordination-based selfassembly process. Firstly, a uniform nanocube-like Y-lysine precursor was simply prepared with hydrothermal treatment. After the simple thermal treatment process, nanocube-shaped yttrium oxides with the morphology inherited from the Y-lysine precursor were successfully prepared. The phase, morphology, size and crystalline structure were well characterized by XRD, SEM and TEM. N2 adsorption-desorption demonstrates the mesoporous characteristics of the Y2O3 nanocubes, showing a relatively high surface area of 60 m2/g.
2014, 25(6): 874-878
doi: 10.1016/j.cclet.2014.03.038
Abstract:
In this work, we developed a templated self-assembly approach to fabricate self-supporting Au/TiO2 binary nanoparticles-nanotubes (NPNTs) for the first time. The stable Au/TiO2 nanoparticles colloids were pre-synthesized and then deposited onto an AAO template, following by a mild calcination process. Au/TiO2 binary NPNTs can be achieved after removing the AAO template by NaOH solution. In addition, Au/TiO2 NPNTs with different thicknesses and size distributions could be achieved by tailoring the process parameters, such as the molar ratio of AuNPs to TiO2NPs, deposition modes and calcinations conditions. Therefore, these findings made controllable formation of Au/TiO2 NPNTs attractive for promising fabrication methodologies of metal/metal oxides NPNTs.
In this work, we developed a templated self-assembly approach to fabricate self-supporting Au/TiO2 binary nanoparticles-nanotubes (NPNTs) for the first time. The stable Au/TiO2 nanoparticles colloids were pre-synthesized and then deposited onto an AAO template, following by a mild calcination process. Au/TiO2 binary NPNTs can be achieved after removing the AAO template by NaOH solution. In addition, Au/TiO2 NPNTs with different thicknesses and size distributions could be achieved by tailoring the process parameters, such as the molar ratio of AuNPs to TiO2NPs, deposition modes and calcinations conditions. Therefore, these findings made controllable formation of Au/TiO2 NPNTs attractive for promising fabrication methodologies of metal/metal oxides NPNTs.
2014, 25(6): 879-882
doi: 10.1016/j.cclet.2014.01.039
Abstract:
Left-handed, coiled, 4,4'-biphenylene bridged polybissilsesquioxane, tubular nanoribbons were prepared according to the published literature. After carbonization and removal of silica using HF aqueous solution, left-handed, coiled, carbonaceous, tubular nanoribbons were obtained. The lefthanded, coiled, carbonaceous, tubular nanoribbons were characterized using field-emission scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, Raman spectrophotometer, diffuse reflectance circular dichroism (DRCD), and N2 adsorptions. Micropores were formed due to the removal of silica. The nitrogen BET surface area is 1727 m2/g. A broad, positive DRCD signal, identified at 40'-800 nm, indicates the carbonaceous, tubular nanoribbons exhibit optical activity. The helical pitch is proposed to play an important role in the position of the DRCD signal.
Left-handed, coiled, 4,4'-biphenylene bridged polybissilsesquioxane, tubular nanoribbons were prepared according to the published literature. After carbonization and removal of silica using HF aqueous solution, left-handed, coiled, carbonaceous, tubular nanoribbons were obtained. The lefthanded, coiled, carbonaceous, tubular nanoribbons were characterized using field-emission scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, Raman spectrophotometer, diffuse reflectance circular dichroism (DRCD), and N2 adsorptions. Micropores were formed due to the removal of silica. The nitrogen BET surface area is 1727 m2/g. A broad, positive DRCD signal, identified at 40'-800 nm, indicates the carbonaceous, tubular nanoribbons exhibit optical activity. The helical pitch is proposed to play an important role in the position of the DRCD signal.
2014, 25(6): 883-886
doi: 10.1016/j.cclet.2014.04.005
Abstract:
Awell-ordered and spherical LiNi0.6Co0.2Mn0.2O2 cathode material was successfully synthesized from Ni and Mn concentration-gradient precursors via co-precipitation. The crystal structure, morphology and electrochemical properties of LiNi0.6Co0.2Mn0.2O2 were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, and charge-discharge tests. The material delivered an initial discharge capacity of 174.3 mAh/g at 180 mA/g (1 C rate) between 2.8 and 4.3 V and more than 93.1% of that was retained after 100 cycles. In addition, it also exhibited excellent rate capability, high cut-off voltage and temperature performance.
Awell-ordered and spherical LiNi0.6Co0.2Mn0.2O2 cathode material was successfully synthesized from Ni and Mn concentration-gradient precursors via co-precipitation. The crystal structure, morphology and electrochemical properties of LiNi0.6Co0.2Mn0.2O2 were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, and charge-discharge tests. The material delivered an initial discharge capacity of 174.3 mAh/g at 180 mA/g (1 C rate) between 2.8 and 4.3 V and more than 93.1% of that was retained after 100 cycles. In addition, it also exhibited excellent rate capability, high cut-off voltage and temperature performance.
2014, 25(6): 887-891
doi: 10.1016/j.cclet.2014.01.012
Abstract:
The novel coordination structures of europium and terbium chloride-picolinamide complexes (EuCl3•(C6H6N2O)2•5H2O, Eu-pa and TbCl3•(C6H6N2O)2•5H2O, Tb-pa) are reported. The crystal structures in the solid state are characterized by X-ray single crystal diffraction, FTIR, Raman, FIR, THz and luminescence spectroscopy. In the crystal structures, the pyridyl nitrogen and carbonyl oxygen atoms in picolinamide are coordinated to the metal ions to form a five-membered ring structure. The experimental results indicate the similar coordination structures of Eu and Tb-pa complexes and the changes of hydrogen bonds and conformation of the ligands induced by complexation. The results provide models for the coordination structures of lanthanide ions with ligands having amide groups.
The novel coordination structures of europium and terbium chloride-picolinamide complexes (EuCl3•(C6H6N2O)2•5H2O, Eu-pa and TbCl3•(C6H6N2O)2•5H2O, Tb-pa) are reported. The crystal structures in the solid state are characterized by X-ray single crystal diffraction, FTIR, Raman, FIR, THz and luminescence spectroscopy. In the crystal structures, the pyridyl nitrogen and carbonyl oxygen atoms in picolinamide are coordinated to the metal ions to form a five-membered ring structure. The experimental results indicate the similar coordination structures of Eu and Tb-pa complexes and the changes of hydrogen bonds and conformation of the ligands induced by complexation. The results provide models for the coordination structures of lanthanide ions with ligands having amide groups.
2014, 25(6): 892-896
doi: 10.1016/j.cclet.2014.03.007
Abstract:
Absolute quantum yield (Φ) is one of the most important parameters to evaluate the potential of novel materials. Lanthanide complexes EuxGd1-x(TTA)3phens are synthesized with the ratio of Gd3+ dopant concentration ranging from 10% to 90% to improve the absolute quantum yield. EuxGd1-x(TTA)3phens possess similar infrared and ultraviolet spectra, showing that they have similar molecular structures. The absolute emission quantum yields of EuxGd1-x(TTA)3phens are determined using a fluoromax-4 spectrofluorometer equipped with an integrating sphere. The fluorescence lifetimes of the EuxGd1-x(TTA)3phens are measured in the same experiment. It was found that both absolute quantum yields and fluorescence lifetimes of EuxGd1-x(TTA)3phens are of quasi-periodic variation with the change of the Gd3+ dopant concentrations. The absolute quantum efficiency and fluorescence lifetime vary with respect to the Gd content in an opposite fashion, indicating that the rate of energy absorption by the EuxGd1-x(TTA)3phens and the conversion to light energy is critical for the absolute quantum efficiency. The radiative rate constant Kr and non-radiative rate constant Knr are calculated. The dependence of Kr and Knr on the Gd3+ dopant concentrations is very similar to that of absolute quantum efficiency. The radiation rate constant Kr and absolute quantum efficiency have a linear relationship.
Absolute quantum yield (Φ) is one of the most important parameters to evaluate the potential of novel materials. Lanthanide complexes EuxGd1-x(TTA)3phens are synthesized with the ratio of Gd3+ dopant concentration ranging from 10% to 90% to improve the absolute quantum yield. EuxGd1-x(TTA)3phens possess similar infrared and ultraviolet spectra, showing that they have similar molecular structures. The absolute emission quantum yields of EuxGd1-x(TTA)3phens are determined using a fluoromax-4 spectrofluorometer equipped with an integrating sphere. The fluorescence lifetimes of the EuxGd1-x(TTA)3phens are measured in the same experiment. It was found that both absolute quantum yields and fluorescence lifetimes of EuxGd1-x(TTA)3phens are of quasi-periodic variation with the change of the Gd3+ dopant concentrations. The absolute quantum efficiency and fluorescence lifetime vary with respect to the Gd content in an opposite fashion, indicating that the rate of energy absorption by the EuxGd1-x(TTA)3phens and the conversion to light energy is critical for the absolute quantum efficiency. The radiative rate constant Kr and non-radiative rate constant Knr are calculated. The dependence of Kr and Knr on the Gd3+ dopant concentrations is very similar to that of absolute quantum efficiency. The radiation rate constant Kr and absolute quantum efficiency have a linear relationship.
2014, 25(6): 897-901
doi: 10.1016/j.cclet.2014.01.010
Abstract:
A novel synthesis of hierarchical porous carbons (HPCs) with 3D open-cell structure based on nanosilicaembedded emulsion-templated polymerization was reported. An oil-in-water emulsion containing SiO2 colloids was fabricated using liquid paraffin as an oil phase, resorcinol/formaldehyde and silica sol as an aqueous phase, and Span 80/Tween 80 as emulsifiers. HPCs with macropore cores, open meso/macropore windows, and abundant micropores were synthesized by the polymerization and carbonization of the emulsion, followed by scaffold removal and further KOH activation. A typical HPCs sample as supercapacitor electrode shows the charge/discharge capability under large loading current density (30 A/g) coupling with a reasonable electrochemical capacitance in KOH electrolyte solution.
A novel synthesis of hierarchical porous carbons (HPCs) with 3D open-cell structure based on nanosilicaembedded emulsion-templated polymerization was reported. An oil-in-water emulsion containing SiO2 colloids was fabricated using liquid paraffin as an oil phase, resorcinol/formaldehyde and silica sol as an aqueous phase, and Span 80/Tween 80 as emulsifiers. HPCs with macropore cores, open meso/macropore windows, and abundant micropores were synthesized by the polymerization and carbonization of the emulsion, followed by scaffold removal and further KOH activation. A typical HPCs sample as supercapacitor electrode shows the charge/discharge capability under large loading current density (30 A/g) coupling with a reasonable electrochemical capacitance in KOH electrolyte solution.
2014, 25(6): 902-906
doi: 10.1016/j.cclet.2014.01.011
Abstract:
A novel energetic combustion catalyst, 4-amino-3,5-dinitropyrazole copper salt ([Cu(adnp)2(H2O)2]), was synthesized in a yield of 93.6% for the first time. The single crystal of [Cu(adnp)2(H2O)2] was determined by single crystal X-ray diffraction. It crystallizes in a triclinic system, space group P 1 with crystal parameters a=5.541(3)Å, b=7.926(4)Å, c=10.231(5)Å, b=101.372(8)°, V=398.3(3)Å3, Z=1, m=1.467 mm-1, F(0 0 0)=243, and Dc=2.000 g cm-3. The thermal behavior and non-isothermal decomposition reaction kinetics of [Cu(adnp)2(H2O)2] were studied by means of different heating rate differential scanning calorimetry (DSC). The kinetic equation of major exothermic decomposition reaction for [Cu(adnp)2(H2O)2] was obtained. The entropy of activation (ΔS≠), enthalpy of activation (ΔH≠), free energy of activation (ΔG≠), the self-accelerating decomposition temperature (TSADT) and the critical temperature of thermal explosion (Tb) are 59.42 J mol-1 K-1, 169.5 kJ mol-1, 1141.26 kJ mol-1, 457.3 K and 468.1 K, respectively.
A novel energetic combustion catalyst, 4-amino-3,5-dinitropyrazole copper salt ([Cu(adnp)2(H2O)2]), was synthesized in a yield of 93.6% for the first time. The single crystal of [Cu(adnp)2(H2O)2] was determined by single crystal X-ray diffraction. It crystallizes in a triclinic system, space group P 1 with crystal parameters a=5.541(3)Å, b=7.926(4)Å, c=10.231(5)Å, b=101.372(8)°, V=398.3(3)Å3, Z=1, m=1.467 mm-1, F(0 0 0)=243, and Dc=2.000 g cm-3. The thermal behavior and non-isothermal decomposition reaction kinetics of [Cu(adnp)2(H2O)2] were studied by means of different heating rate differential scanning calorimetry (DSC). The kinetic equation of major exothermic decomposition reaction for [Cu(adnp)2(H2O)2] was obtained. The entropy of activation (ΔS≠), enthalpy of activation (ΔH≠), free energy of activation (ΔG≠), the self-accelerating decomposition temperature (TSADT) and the critical temperature of thermal explosion (Tb) are 59.42 J mol-1 K-1, 169.5 kJ mol-1, 1141.26 kJ mol-1, 457.3 K and 468.1 K, respectively.
2014, 25(6): 907-911
doi: 10.1016/j.cclet.2014.04.031
Abstract:
Pt:Pd:Co ternary alloy nanoparticles were synthesized by sodium borohydride reduction under nitrogen, and were supported on carbon black as catalysts for methanol and formic acid electro-oxidation. Compared with Pt0.65Co0.30/C, Pt/C, Pd0.65Co0.30/C, and Pd/C catalyst, Pt0.35Pd0.35Co0.30/C exhibited relatively high durability and strong poisoning resistance, and the Pt-mass activity was 3.6 times higher than that of Pt/C in methanol oxidation reaction. Meanwhile, the Pt0.35Pd0.35Co0.30/C exhibited excellent activity with higher current density and higher CO tolerance than that of Pt0.65Co0.30/C, Pt/C, Pd0.65Co0.30/C, and Pd/C in formic acid electro-oxidation.
Pt:Pd:Co ternary alloy nanoparticles were synthesized by sodium borohydride reduction under nitrogen, and were supported on carbon black as catalysts for methanol and formic acid electro-oxidation. Compared with Pt0.65Co0.30/C, Pt/C, Pd0.65Co0.30/C, and Pd/C catalyst, Pt0.35Pd0.35Co0.30/C exhibited relatively high durability and strong poisoning resistance, and the Pt-mass activity was 3.6 times higher than that of Pt/C in methanol oxidation reaction. Meanwhile, the Pt0.35Pd0.35Co0.30/C exhibited excellent activity with higher current density and higher CO tolerance than that of Pt0.65Co0.30/C, Pt/C, Pd0.65Co0.30/C, and Pd/C in formic acid electro-oxidation.
2014, 25(6): 912-914
doi: 10.1016/j.cclet.2014.03.041
Abstract:
A facile approach for constructing diverse architectures of unmodified C60 was developed via simple evaporation of pure C60 solution in CS2 under various poor solvent atmospheres. Diverse architectures such as belts, sheets, and starfishes were successfully constructed under different experimental conditions. C60 belts obtained under EtOH atmosphere were confirmed to be a face-centered cubic (fcc) structure. The solvent atmospheres not only slowed down the evaporation speed, but also could reorganize the self-assembly of C60 by partially re-dissolving the initially formed architectures. This concept represents a novel method for preparation of nanostructures of C60 and could also be applied for controlling of the self-assembly of other functional organic molecules.
A facile approach for constructing diverse architectures of unmodified C60 was developed via simple evaporation of pure C60 solution in CS2 under various poor solvent atmospheres. Diverse architectures such as belts, sheets, and starfishes were successfully constructed under different experimental conditions. C60 belts obtained under EtOH atmosphere were confirmed to be a face-centered cubic (fcc) structure. The solvent atmospheres not only slowed down the evaporation speed, but also could reorganize the self-assembly of C60 by partially re-dissolving the initially formed architectures. This concept represents a novel method for preparation of nanostructures of C60 and could also be applied for controlling of the self-assembly of other functional organic molecules.
2014, 25(6): 915-918
doi: 10.1016/j.cclet.2014.04.013
Abstract:
Rose flower-like SnO hierarchical 3D architectures consisting of well-ordered microsheets were synthesized by a template-free and surfactant-free hydrothermal method based on the reaction between SnCl2 and NaOH in ethanol/water. The ethanol amount is a crucial factor in controlling the size and morphology of the microsheets. Ethanol can accelerate the delamination of the SnO blocks to the microsheets, and the microsheets changed from a quasi square to an octodecahedral shape with the increase of the ethanol ratio. When the volume ratio of ethanol/water is 2:1, the microstructure of SnO presents a rose flower-like hierarchical architecture with a diameter of about 40 mm, which is regularly composed of numerous well-ordered thin microsheets with octodecahedral shape, and the microsheets were formed by countless nanoparticles. A possible growth mechanism of the architectures was proposed. Moreover, SnO2 nanospheres were synthesized by a similar experiment only without NaOH, which showed that NaOH was crucial to the formation of SnOx.
Rose flower-like SnO hierarchical 3D architectures consisting of well-ordered microsheets were synthesized by a template-free and surfactant-free hydrothermal method based on the reaction between SnCl2 and NaOH in ethanol/water. The ethanol amount is a crucial factor in controlling the size and morphology of the microsheets. Ethanol can accelerate the delamination of the SnO blocks to the microsheets, and the microsheets changed from a quasi square to an octodecahedral shape with the increase of the ethanol ratio. When the volume ratio of ethanol/water is 2:1, the microstructure of SnO presents a rose flower-like hierarchical architecture with a diameter of about 40 mm, which is regularly composed of numerous well-ordered thin microsheets with octodecahedral shape, and the microsheets were formed by countless nanoparticles. A possible growth mechanism of the architectures was proposed. Moreover, SnO2 nanospheres were synthesized by a similar experiment only without NaOH, which showed that NaOH was crucial to the formation of SnOx.
2014, 25(6): 919-922
doi: 10.1016/j.cclet.2014.05.006
Abstract:
We describe a novel method for the synthesis a new magnetic bromochromate hybrid nanomaterial, Fe3O4@SiO2@TEA@[CrO3Br], as a catalyst.Thephysical properties,morphology andmagnetic investigations of magnetic bromochromate hybrid nanomaterials are identified by transmission electron microscopy (TEM), scanning electronmicroscopy (SEM)and vibrating samplemagnetometer (VSM)techniques. Fourier transform infrared (FT-IR), elemental analysis, X-ray fluorescence (XRF), X-ray diffraction (XRD) were also used for structural identification. The quantity of chromiumis approximately 0.38%, which confirms to the immobilization amount of [CrO3Br] and is equal to 0.007 mol/100 g.
We describe a novel method for the synthesis a new magnetic bromochromate hybrid nanomaterial, Fe3O4@SiO2@TEA@[CrO3Br], as a catalyst.Thephysical properties,morphology andmagnetic investigations of magnetic bromochromate hybrid nanomaterials are identified by transmission electron microscopy (TEM), scanning electronmicroscopy (SEM)and vibrating samplemagnetometer (VSM)techniques. Fourier transform infrared (FT-IR), elemental analysis, X-ray fluorescence (XRF), X-ray diffraction (XRD) were also used for structural identification. The quantity of chromiumis approximately 0.38%, which confirms to the immobilization amount of [CrO3Br] and is equal to 0.007 mol/100 g.
2014, 25(6): 923-928
doi: 10.1016/j.cclet.2014.03.006
Abstract:
Usingmagnetic layered double hydroxide (MLDH) as carrier of fluorescein (FLU), a fluorescent composite of MLDH-FLU was prepared via intercalation reaction of ion change. The crystal properties of MLDH-FLU were investigated through XRD, IR, TEM and TG-DSC characterization. It is shown that the crystal type of MLDH-FLU composite matched well with R-hexagonal crystal system of MLDH, with crystal cell parameters of a, c and channel height h equal to 0.3199, 2.411 and 0.3267 nm respectively. The superabundant pigment adsorbed outside the composite should be cleared before interference with cells, but excessive wash would decrease stability and cause crystal phase transformation of MLDH.
Usingmagnetic layered double hydroxide (MLDH) as carrier of fluorescein (FLU), a fluorescent composite of MLDH-FLU was prepared via intercalation reaction of ion change. The crystal properties of MLDH-FLU were investigated through XRD, IR, TEM and TG-DSC characterization. It is shown that the crystal type of MLDH-FLU composite matched well with R-hexagonal crystal system of MLDH, with crystal cell parameters of a, c and channel height h equal to 0.3199, 2.411 and 0.3267 nm respectively. The superabundant pigment adsorbed outside the composite should be cleared before interference with cells, but excessive wash would decrease stability and cause crystal phase transformation of MLDH.
2014, 25(6): 929-932
doi: 10.1016/j.cclet.2014.03.039
Abstract:
In this paper, activated carbons (ACs) with high specific surface areas were successfully synthesized by simple one-step carbonization-activation from paulownia sawdust biomass, and the effects of the synthetic conditions on their CO2 capture capacity were investigated as well. The results show that, when the mass ratio between activator and biomass is 4, the activation temperature is 700℃ and the activation time is 1 h, as-made AC provides the most micropores for CO2 adsorption. As a consequence, the maximum CO2 uptake of 8.0 mmol/g is obtained at 0℃ and 1 bar.
In this paper, activated carbons (ACs) with high specific surface areas were successfully synthesized by simple one-step carbonization-activation from paulownia sawdust biomass, and the effects of the synthetic conditions on their CO2 capture capacity were investigated as well. The results show that, when the mass ratio between activator and biomass is 4, the activation temperature is 700℃ and the activation time is 1 h, as-made AC provides the most micropores for CO2 adsorption. As a consequence, the maximum CO2 uptake of 8.0 mmol/g is obtained at 0℃ and 1 bar.
2014, 25(6): 933-936
doi: 10.1016/j.cclet.2014.01.013
Abstract:
This study aims at preparing water soluble aspartic acid (ASP)modified CdTe quantum dots with tunable fluorescence emission controlled by reaction time. The size of the synthesized CdTe quantum dots was evaluated using transmission electron microscope (TEM) and also calculated based on their UV-vis spectra. The optical properties of TGA-CdTe quantum dots were characterized by UV-vis and fluorescence (FL) spectroscopy. The red-shift in the UV-vis absorption and FL emission with the increase of reaction time was observed. The biocompatibility examination indicated that the ASP modified CdTe QDs had low cytotoxicity.
This study aims at preparing water soluble aspartic acid (ASP)modified CdTe quantum dots with tunable fluorescence emission controlled by reaction time. The size of the synthesized CdTe quantum dots was evaluated using transmission electron microscope (TEM) and also calculated based on their UV-vis spectra. The optical properties of TGA-CdTe quantum dots were characterized by UV-vis and fluorescence (FL) spectroscopy. The red-shift in the UV-vis absorption and FL emission with the increase of reaction time was observed. The biocompatibility examination indicated that the ASP modified CdTe QDs had low cytotoxicity.
2014, 25(6): 937-940
doi: 10.1016/j.cclet.2014.01.009
Abstract:
The bimetallic hexanuclear cluster [Mn4Ni2O2(Cl-Sao)6•(CH3OH)8]•10CH3OH (1) was synthesized. Single-crystal X-ray analysis reveals that 1 consists of two [Mn2Ni(μ3-O)(Cl-Sao)3] subunits linked together via two pairs of long Ni-O bonds involving two oximate oxygen atoms and two phenolate oxygen atoms. Each Mn and Ni center achieves six-coordination with axialmethanol molecules. The spin centers of the MnIII and NiII ions exchange magnetic coupling through O2-, Ophenolate- and -N-O-bridges. The magnetic properties of the cluster have been investigated.
The bimetallic hexanuclear cluster [Mn4Ni2O2(Cl-Sao)6•(CH3OH)8]•10CH3OH (1) was synthesized. Single-crystal X-ray analysis reveals that 1 consists of two [Mn2Ni(μ3-O)(Cl-Sao)3] subunits linked together via two pairs of long Ni-O bonds involving two oximate oxygen atoms and two phenolate oxygen atoms. Each Mn and Ni center achieves six-coordination with axialmethanol molecules. The spin centers of the MnIII and NiII ions exchange magnetic coupling through O2-, Ophenolate- and -N-O-bridges. The magnetic properties of the cluster have been investigated.
2014, 25(6): 941-946
doi: 10.1016/j.cclet.2014.03.050
Abstract:
A novel composite, CdSe-graphene, was synthesized using facile hydrothermal method. The structural characteristics studies of the synthesized composites were investigated by X-ray diffraction (XRD), scanning electronmicroscope (SEM), transmission electronmicroscope (TEM), Brunauer, Emmett, Teller specific surface area (BET) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity was investigated by the degradation of methylene blue as standard dye. The degradation of MB was calculated based on the decrease in concentration of the dye with respect to regular time intervals. The reusability tests were done to investigate the stability of the used catalysts. Additionally the antibacterial activity of CdSe-graphene was also investigated using bacterium Streptococcus aureus (S. aureus).
A novel composite, CdSe-graphene, was synthesized using facile hydrothermal method. The structural characteristics studies of the synthesized composites were investigated by X-ray diffraction (XRD), scanning electronmicroscope (SEM), transmission electronmicroscope (TEM), Brunauer, Emmett, Teller specific surface area (BET) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity was investigated by the degradation of methylene blue as standard dye. The degradation of MB was calculated based on the decrease in concentration of the dye with respect to regular time intervals. The reusability tests were done to investigate the stability of the used catalysts. Additionally the antibacterial activity of CdSe-graphene was also investigated using bacterium Streptococcus aureus (S. aureus).
2014, 25(6): 947-952
doi: 10.1016/j.cclet.2014.04.009
Abstract:
Pre-treatment process is the key step for electroless plating. Once a suitable pre-treatment film is in place, the desired metals can be plated. In this paper, Ni-P coating was successfully prepared on AZ33 magnesium alloy with Mg(OH)2 pre-treatment film by electroless plating. To investigate the role of MgF2 in Ni-P coating, the deposition procedures between Mg(OH)2 pre-treatment film and Mg(OH)2-MgF2 pre-treatment film (a traditional process) were compared. The surfacemorphology variations of coatings were observed with scanning electron microscopy and the compositions were analyzed by energy dispersive spectrometry. The results showed that during the plating, both MgF2 and Ni-P deposited at the initial stage, and MgF2 distributed in the bottom of the coating, forming a transitional interlayer with Ni-P. According to the heat quench test, a poor adhesion of the coating mainly occurred between the MgF2 and Ni-P coating.
Pre-treatment process is the key step for electroless plating. Once a suitable pre-treatment film is in place, the desired metals can be plated. In this paper, Ni-P coating was successfully prepared on AZ33 magnesium alloy with Mg(OH)2 pre-treatment film by electroless plating. To investigate the role of MgF2 in Ni-P coating, the deposition procedures between Mg(OH)2 pre-treatment film and Mg(OH)2-MgF2 pre-treatment film (a traditional process) were compared. The surfacemorphology variations of coatings were observed with scanning electron microscopy and the compositions were analyzed by energy dispersive spectrometry. The results showed that during the plating, both MgF2 and Ni-P deposited at the initial stage, and MgF2 distributed in the bottom of the coating, forming a transitional interlayer with Ni-P. According to the heat quench test, a poor adhesion of the coating mainly occurred between the MgF2 and Ni-P coating.
2014, 25(6): 953-956
doi: 10.1016/j.cclet.2014.03.025
Abstract:
The pure TiO2 and Fe salts [Fe(C2O4)2•5H2O]-doped TiO2 electrodes were prepared by the hydrothermal method. The pure TiO2 or Fe-doped TiO2 slurry was coated onto the fluorine-doped tin oxide glass substrate by the Doctor Blade method and then sintered at 450℃. The Mott-Schottky plot indicates that the flat band potential of TiO2 was shifted positively after Fe-doped TiO2. The positive shift of the flat band potential improves the driving force of injected electrons from the LUMO of the dye to the conduction band of TiO2. This study shows that photovoltaic efficiency increased by 22.9% from 6.07% to 7.46% compared to pure TiO2, and the fill factors increased from 0.53 to 0.63.
The pure TiO2 and Fe salts [Fe(C2O4)2•5H2O]-doped TiO2 electrodes were prepared by the hydrothermal method. The pure TiO2 or Fe-doped TiO2 slurry was coated onto the fluorine-doped tin oxide glass substrate by the Doctor Blade method and then sintered at 450℃. The Mott-Schottky plot indicates that the flat band potential of TiO2 was shifted positively after Fe-doped TiO2. The positive shift of the flat band potential improves the driving force of injected electrons from the LUMO of the dye to the conduction band of TiO2. This study shows that photovoltaic efficiency increased by 22.9% from 6.07% to 7.46% compared to pure TiO2, and the fill factors increased from 0.53 to 0.63.
2014, 25(6): 957-961
doi: 10.1016/j.cclet.2014.05.032
Abstract:
A new application ofmetal organic framework (MOF) as a pseudo-capacitive material for supercapacitors is investigated. To this end, a simple nickel-based MOF, formulated Ni3(btc)2•12H2O, is synthesized via a hydrothermal reaction. As an electro-active material, such nickel-based MOF exhibits superior pseudocapacitive behavior in KOH aqueous electrolyte with a high specific capacitance of 726 F g-1. Also, it displays good electrochemical stability with 94.6% of the initial capacitance over consecutive 1000 cycles. In addition, a simple asymmetric supercapacitor with a high energy density of 16.5 Wh kg-1 is successfully built using the nickel-based MOF as positive electrode and commercial activated carbon as negative electrode in KOH electrolyte.
A new application ofmetal organic framework (MOF) as a pseudo-capacitive material for supercapacitors is investigated. To this end, a simple nickel-based MOF, formulated Ni3(btc)2•12H2O, is synthesized via a hydrothermal reaction. As an electro-active material, such nickel-based MOF exhibits superior pseudocapacitive behavior in KOH aqueous electrolyte with a high specific capacitance of 726 F g-1. Also, it displays good electrochemical stability with 94.6% of the initial capacitance over consecutive 1000 cycles. In addition, a simple asymmetric supercapacitor with a high energy density of 16.5 Wh kg-1 is successfully built using the nickel-based MOF as positive electrode and commercial activated carbon as negative electrode in KOH electrolyte.
2014, 25(6): 962-966
doi: 10.1016/j.cclet.2014.05.034
Abstract:
Rod-shaped mesoporous titanosilicate composites (RMTSs) with controllable aspect ratios (ARs) were fabricated using cetyltrimethylammonium bromide (CTAB) and ammonium hydroxide (NH4OH) at a continuous stirring rate, resulting in ARs ranging from 1 to 5. Slowing the stirring rate or increasing the concentration of CTAB mainly impacted the length growth, whereas NH4OH affected the width growth. Photocatalytic activity studies revealed that the length of RMTSs played a more significant role than the width at lower ARs in their photocatalytic activity.
Rod-shaped mesoporous titanosilicate composites (RMTSs) with controllable aspect ratios (ARs) were fabricated using cetyltrimethylammonium bromide (CTAB) and ammonium hydroxide (NH4OH) at a continuous stirring rate, resulting in ARs ranging from 1 to 5. Slowing the stirring rate or increasing the concentration of CTAB mainly impacted the length growth, whereas NH4OH affected the width growth. Photocatalytic activity studies revealed that the length of RMTSs played a more significant role than the width at lower ARs in their photocatalytic activity.
2014, 25(6): 967-971
doi: 10.1016/j.cclet.2014.05.038
Abstract:
Reacting homochiral (R)-2-methylpiperazine with cobalt sulfate heptahydrate by the solution method in the presence of concentrated sulfuric acid (H2SO4) yielded two coordination compounds (C5H14N2) [Co(H2O)6](SO4)2 (1 and 2). They are polymorphs, but their hydrogen bonds structure differ significantly. Both 1 and 2 crystallize in chiral space group P21 which is related with point group C2, and experimental results suggest that 1 displays ferroelectric behaviors.
Reacting homochiral (R)-2-methylpiperazine with cobalt sulfate heptahydrate by the solution method in the presence of concentrated sulfuric acid (H2SO4) yielded two coordination compounds (C5H14N2) [Co(H2O)6](SO4)2 (1 and 2). They are polymorphs, but their hydrogen bonds structure differ significantly. Both 1 and 2 crystallize in chiral space group P21 which is related with point group C2, and experimental results suggest that 1 displays ferroelectric behaviors.
