The reductive cyclocoupling of isocyanides is a pivotal reaction that facilitates the rapid construction of intricate cyclic compounds in a single-step process.In this work,treatment of simple precursor1(Cp^(#)CrLCl,L...The reductive cyclocoupling of isocyanides is a pivotal reaction that facilitates the rapid construction of intricate cyclic compounds in a single-step process.In this work,treatment of simple precursor1(Cp^(#)CrLCl,L=CAAC,NHC,PCy_(3),or PPh_(2)Et;Cp^(#)=Cp^(*)or Cp^(*TMS))with XylNC(2,6-dimethylphenyl isocyanide)led to the reductive coupling of isocyanides,yielding either complex 2{(Cp^(*TMS)Cr)_(2)[μ-C_(4)(NXyl)_(4)]}or complex 6{(Cp^(*)CrCl)_(2)[μ-C_(4)(NXyl)_(4)]},corresponding to the tetramerization of isocyanides.Control experiments and in-situ monitoring were carried out to understand the reaction mechanism,revealing various side reaction pathways during the isocyanide tetramerization.SQUID and DFT calculations provided insights into the electronic structures.In complex 2,the energies of nonet and broken-symmetry singlet states are close and significantly lower than other spin states,indicating two independent highspin Cr(Ⅱ)centers with weak antiferromagnetic coupling.A similar situation is observed in complex 6,where two independent high-spin Cr(Ⅲ)centers are coupled antiferromagnetically.In both complexes 2 and 6,the tetrameric isocyanide rings,receiving two electrons from Cr centers,show averaged bond lengths and display moderate aromatic characteristics.展开更多
Since microwave irradiation could promote hydrolysis and olation of chromium tanning liquor,but the influence of microwave on chromium complex component in the liquor was still unknown.Chromium sulphate solution(0%bas...Since microwave irradiation could promote hydrolysis and olation of chromium tanning liquor,but the influence of microwave on chromium complex component in the liquor was still unknown.Chromium sulphate solution(0%basicity)and 33%basicity chromium tanning liquor were subjected microwave(MW)and water bath(WB)heating,and the samples without any warming were regarded as control.Ion exchange chromatography(IEC)and gel filtration chromatography(GFC)were used to measure the charge composition and molecular size of chromium complexes in each sample.FT-IR was used to characterize the structure of chromium complexes in each composition separated by IEC.Moreover,the chromium tanning liquor after warming was used in hide powder tanning trials to illustrate whether microwave would affect its tanning ability.The results show there are more high positive charge and large molecular size complexes in chromium tanning liquor after warming but the phenomena are more significant in MW samples compared with WB due to non-thermal effect of microwave.In addition,microwave has more powerful effect on 33%basicity chromium tanning liquor hydrolysis and olation to generate larger molecular size complexes.In FT-IR results,the combination pattern between chromium and ligands are changed after warming but there is no difference between WB and MW.The chromium exhaustion and thermal stability of hide powder tanned with chromium tanning liquor after microwave irradiation are both higher.It could conclude that both thermal and non-thermal effects of microwave promote the process together,and the nonthermal effect leads to more high positive charge and large molecular size complexes and has stronger influence on high polarity system.In short,this work would provide theoretical basis for applying microwave in tanning agent modification and chrome tanning process further.展开更多
Three electrokinetic（EK） experiments were designed to study the remediation efficiency of Cr（Ⅲ） by EK-oxidation method and to investigate the influence of complexes and p H buffer solution in EK-oxidation process...Three electrokinetic（EK） experiments were designed to study the remediation efficiency of Cr（Ⅲ） by EK-oxidation method and to investigate the influence of complexes and p H buffer solution in EK-oxidation process. Sediments Cr（Ⅲ） can be oxidized into Cr（Ⅵ） effectively by KMn O4, but the oxidation efficiency is not proportional to the dose of oxidant, and chemical oxidation process leads to a bit lower buffering capacity of the sediment. Compared with the simple EK remediation, the removal efficiency of total Cr in the sediments increased 32.6% by EK-oxidation method, and the concentrations of total chromium in the sediment showed increasing trend from the cathode to the anode after EK-oxidation treatment. The p H control and KMn O4 improved the removal of Cr（Ⅵ） and total Cr from the sediments. Due to stronger complexation action of citric acid with Cr（Ⅲ） in sediments, citric acid in the catholyte obviously increased the removal rate of total Cr in sediments. Finally, the removal rate of total Cr from sediments reached 60.9% by adding complex and controlling the p H of cathode and anode pond solution on EK-oxidation processes.展开更多
The novel chromium（Ⅲ） complex with salicylaldehyde semicarbazone was synthesized and characterized by IR spectra and single-crystal X-ray diffraction analysis. The crystal belongs to the orthorhombic system, space ...The novel chromium（Ⅲ） complex with salicylaldehyde semicarbazone was synthesized and characterized by IR spectra and single-crystal X-ray diffraction analysis. The crystal belongs to the orthorhombic system, space group Pbca with a = 8.9849（13）, b = 12.0475（16）, c = 34.522（5）A, V = 3736.9（9）A3, Z = 8, C16H18C1CrN6O5, Mr= 461.81, De= 1.642 g/cm^3, F（000） = 1896,A（MoKα） = 0.799 mm^-1, the final R = 0.0370 and wR = 0.0827 for 2908 observed reflections with I 〉 2σ（I）. The interaction between the chromium（Ⅲ） complex with calf thymus DNA （Ct-DNA） has been investigated by absorption spectroscopy, fluorescence spectroscopy and viscosity measurements. The results indicated that the complex was bonded to Ct-DNA through a non-classical intercalative mode.展开更多
Inoculation of high chromium cast iron is made by RE complex inoculant. Influence of inoculating on rolling fatigue wear characteristics of high chromium cast iron is investigated. The experimental resutls indicate th...Inoculation of high chromium cast iron is made by RE complex inoculant. Influence of inoculating on rolling fatigue wear characteristics of high chromium cast iron is investigated. The experimental resutls indicate that high chromium cast iron inoculated by RE complex inoculation is improved in structure and properties, i. e. fatigue wear sevice life is prolonged and relative wear resistance is increased greatly.展开更多
The preparation process of the Cr（III） bath was studied based on a perspective of accelerating the formation of active Cr（III） complexes. The results of ultraviolet-visible absorption spectroscopy （UV-Vis） and e...The preparation process of the Cr（III） bath was studied based on a perspective of accelerating the formation of active Cr（III） complexes. The results of ultraviolet-visible absorption spectroscopy （UV-Vis） and electrodeposition showed that active Cr（III） complexes in the bath prepared at room temperature in several days were rare for depositing chromium. The increase of heating temperature, time, and pH value during the bath preparation promoted the formation of active Cr（III） complexes. The chromium deposition rate increased with the concentration of active Cr（III） complexes increasing. Increasing the heating temperature from 60 to 96℃, the chromium deposition rate increased from 0.40 to 0.71μm/min. When the concentration of active Cr（III） complexes increased, the grain size of Cr coatings increased, and the carbon content of the coating decreased. It is deduced that Cr（H20）4（OH）L2＋ （L is an organic ligand, and its valence is omitted） is a primary active Cr（III） complex.展开更多
The chromium(Ⅲ)complexes with rutin and quercetin were synthesized and characterized by IR,UV-vis,element analysis,AAS,TG-DSC-DTG respectively.The results indicated that Cr3+ formed steady complexes with rutin and qu...The chromium(Ⅲ)complexes with rutin and quercetin were synthesized and characterized by IR,UV-vis,element analysis,AAS,TG-DSC-DTG respectively.The results indicated that Cr3+ formed steady complexes with rutin and quercetin.展开更多
基金the financial support by the National Natural Science Foundation of China(No.22201013)。
文摘The reductive cyclocoupling of isocyanides is a pivotal reaction that facilitates the rapid construction of intricate cyclic compounds in a single-step process.In this work,treatment of simple precursor1(Cp^(#)CrLCl,L=CAAC,NHC,PCy_(3),or PPh_(2)Et;Cp^(#)=Cp^(*)or Cp^(*TMS))with XylNC(2,6-dimethylphenyl isocyanide)led to the reductive coupling of isocyanides,yielding either complex 2{(Cp^(*TMS)Cr)_(2)[μ-C_(4)(NXyl)_(4)]}or complex 6{(Cp^(*)CrCl)_(2)[μ-C_(4)(NXyl)_(4)]},corresponding to the tetramerization of isocyanides.Control experiments and in-situ monitoring were carried out to understand the reaction mechanism,revealing various side reaction pathways during the isocyanide tetramerization.SQUID and DFT calculations provided insights into the electronic structures.In complex 2,the energies of nonet and broken-symmetry singlet states are close and significantly lower than other spin states,indicating two independent highspin Cr(Ⅱ)centers with weak antiferromagnetic coupling.A similar situation is observed in complex 6,where two independent high-spin Cr(Ⅲ)centers are coupled antiferromagnetically.In both complexes 2 and 6,the tetrameric isocyanide rings,receiving two electrons from Cr centers,show averaged bond lengths and display moderate aromatic characteristics.
基金National Natural Science Foundation of China(No.21576171).
文摘Since microwave irradiation could promote hydrolysis and olation of chromium tanning liquor,but the influence of microwave on chromium complex component in the liquor was still unknown.Chromium sulphate solution(0%basicity)and 33%basicity chromium tanning liquor were subjected microwave(MW)and water bath(WB)heating,and the samples without any warming were regarded as control.Ion exchange chromatography(IEC)and gel filtration chromatography(GFC)were used to measure the charge composition and molecular size of chromium complexes in each sample.FT-IR was used to characterize the structure of chromium complexes in each composition separated by IEC.Moreover,the chromium tanning liquor after warming was used in hide powder tanning trials to illustrate whether microwave would affect its tanning ability.The results show there are more high positive charge and large molecular size complexes in chromium tanning liquor after warming but the phenomena are more significant in MW samples compared with WB due to non-thermal effect of microwave.In addition,microwave has more powerful effect on 33%basicity chromium tanning liquor hydrolysis and olation to generate larger molecular size complexes.In FT-IR results,the combination pattern between chromium and ligands are changed after warming but there is no difference between WB and MW.The chromium exhaustion and thermal stability of hide powder tanned with chromium tanning liquor after microwave irradiation are both higher.It could conclude that both thermal and non-thermal effects of microwave promote the process together,and the nonthermal effect leads to more high positive charge and large molecular size complexes and has stronger influence on high polarity system.In short,this work would provide theoretical basis for applying microwave in tanning agent modification and chrome tanning process further.
基金Supported by the“Twelfth Five-Year”National Science and Technology Major Projects(2014ZX07104-005)
文摘Three electrokinetic（EK） experiments were designed to study the remediation efficiency of Cr（Ⅲ） by EK-oxidation method and to investigate the influence of complexes and p H buffer solution in EK-oxidation process. Sediments Cr（Ⅲ） can be oxidized into Cr（Ⅵ） effectively by KMn O4, but the oxidation efficiency is not proportional to the dose of oxidant, and chemical oxidation process leads to a bit lower buffering capacity of the sediment. Compared with the simple EK remediation, the removal efficiency of total Cr in the sediments increased 32.6% by EK-oxidation method, and the concentrations of total chromium in the sediment showed increasing trend from the cathode to the anode after EK-oxidation treatment. The p H control and KMn O4 improved the removal of Cr（Ⅵ） and total Cr from the sediments. Due to stronger complexation action of citric acid with Cr（Ⅲ） in sediments, citric acid in the catholyte obviously increased the removal rate of total Cr in sediments. Finally, the removal rate of total Cr from sediments reached 60.9% by adding complex and controlling the p H of cathode and anode pond solution on EK-oxidation processes.
基金Supported by the Scientific Research Common Program of Beijing Municipal Commission of Education, PRC (KM200510028005)
文摘The novel chromium（Ⅲ） complex with salicylaldehyde semicarbazone was synthesized and characterized by IR spectra and single-crystal X-ray diffraction analysis. The crystal belongs to the orthorhombic system, space group Pbca with a = 8.9849（13）, b = 12.0475（16）, c = 34.522（5）A, V = 3736.9（9）A3, Z = 8, C16H18C1CrN6O5, Mr= 461.81, De= 1.642 g/cm^3, F（000） = 1896,A（MoKα） = 0.799 mm^-1, the final R = 0.0370 and wR = 0.0827 for 2908 observed reflections with I 〉 2σ（I）. The interaction between the chromium（Ⅲ） complex with calf thymus DNA （Ct-DNA） has been investigated by absorption spectroscopy, fluorescence spectroscopy and viscosity measurements. The results indicated that the complex was bonded to Ct-DNA through a non-classical intercalative mode.
文摘Inoculation of high chromium cast iron is made by RE complex inoculant. Influence of inoculating on rolling fatigue wear characteristics of high chromium cast iron is investigated. The experimental resutls indicate that high chromium cast iron inoculated by RE complex inoculation is improved in structure and properties, i. e. fatigue wear sevice life is prolonged and relative wear resistance is increased greatly.
基金financially supported by the National Basic Research and Development Program of China(No.2013CB632606)the National Natural Science Foundation of China(No.51274180)
文摘The preparation process of the Cr（III） bath was studied based on a perspective of accelerating the formation of active Cr（III） complexes. The results of ultraviolet-visible absorption spectroscopy （UV-Vis） and electrodeposition showed that active Cr（III） complexes in the bath prepared at room temperature in several days were rare for depositing chromium. The increase of heating temperature, time, and pH value during the bath preparation promoted the formation of active Cr（III） complexes. The chromium deposition rate increased with the concentration of active Cr（III） complexes increasing. Increasing the heating temperature from 60 to 96℃, the chromium deposition rate increased from 0.40 to 0.71μm/min. When the concentration of active Cr（III） complexes increased, the grain size of Cr coatings increased, and the carbon content of the coating decreased. It is deduced that Cr（H20）4（OH）L2＋ （L is an organic ligand, and its valence is omitted） is a primary active Cr（III） complex.
文摘The chromium(Ⅲ)complexes with rutin and quercetin were synthesized and characterized by IR,UV-vis,element analysis,AAS,TG-DSC-DTG respectively.The results indicated that Cr3+ formed steady complexes with rutin and quercetin.
