A novel solid Bronsted-Lewis acid catalyst La-PW-SiO_(2)/SWCNTs(single-wall carbon nanotubes)was synthesized from the synergistic modification of H_(3)PW_(12)O_(40)(HPW)by single-walled carbon nanotubes functionalized...A novel solid Bronsted-Lewis acid catalyst La-PW-SiO_(2)/SWCNTs(single-wall carbon nanotubes)was synthesized from the synergistic modification of H_(3)PW_(12)O_(40)(HPW)by single-walled carbon nanotubes functionalized with sidewall hydroxyl groups(SWCNTs–OH)and La^(3+) via sol–gel method.The freshly prepared catalyst was characterized by several methods,and the catalytic activity and stability of it were studied from the esterification of oleic acid and methanol.Results showed that the highest conversion of oleic acid was 93.1%(mass)and maintained as high as 88.7%(mass)after six cycles of La-PW-SiO_(2)/SWCNTs.The high catalytic activity and stability of La-PW-SiO_(2)/SWCNTs can be attributed to the strong electron withdrawing effect of La^(3+) on π bond of SWCNTs,because it can facilitate the formation of a large number of strong Lewis acid sites.Therefore,the reduction of catalytic activity of a solid acid catalyst due to the fact that hydration reaction of its Bronsted acid sites can be effectively reduced.La-PW-SiO_(2)/SWCNTs can be an efficient and economical catalyst,because it shows good catalytic activity and stability.展开更多
We report an exclusively tandem C—O and C—C bond forming beyond the esterification and cyclization reaction of 2-acylbenzoic acids with alcohols to regio-and stereoselective synthesis of the(Z)-3-ylidenephthalides.T...We report an exclusively tandem C—O and C—C bond forming beyond the esterification and cyclization reaction of 2-acylbenzoic acids with alcohols to regio-and stereoselective synthesis of the(Z)-3-ylidenephthalides.The reaction uses the nontoxic,inexpensive H_(3)PMo1_(2)O_(40) as catalyst and produces water as the sole by-product,making the reaction environmentally benign and sustainable.Moreover,this reaction features an eco-friendly reaction condition,facile scalability,and easy derivatization of the products to drugs and bioactive compounds.The mechanism studies and density functional theory calculations reveal that the appropriate acid catalyst is the key to the selectivity of this transformation.展开更多
It has been found that the two-phase reactions of aqueous HCl, HOAc or H_3PO_4 with primary amine N_ 1923 in chloroform are oscillating reactions. Their power-time curves were measured by the titration microcalorimet...It has been found that the two-phase reactions of aqueous HCl, HOAc or H_3PO_4 with primary amine N_ 1923 in chloroform are oscillating reactions. Their power-time curves were measured by the titration microcalorimetric method, and the induction period (t_ in). The first oscillating period (t_ p.1) and the second oscillating period (t_ p.2) were determined. The apparent activating parameters and the orders of the oscillating systems were calculated and the following relationships were established: for the oscillating system of hydrochloric acid t_ in∝c 0.147_ HClexp(1.35×10 3T), t_ p.1∝c 0.241_ HCl· exp(4.33×10 3T), t_ p.2∝c 0.290_ HClexp(5.59×10 3T); for the oscillating system of acetic acid, t_ in∝c 0.883_ HOAcexp(2.32×10 3T), t_ p.1∝c 0.399_ HOAc· exp(4.50×10 3T), t_ p.2∝c 0.301_ HOAcexp(5.88×10 3T); for the oscillating system of phosphoric acid, t_ in∝c 1.14_ H_3PO_4exp(7.70×10 4T), t_ p.1∝c 1.42_ H_3PO_4exp(1.14×10 4T), t_ p.2∝c 1.47_ H_3PO_4exp(1.27×10 4T).展开更多
A shape-persistent dendritic molecule,tris(4-(2,7-dibromo-9-phenyl-9-fluoren-9-yl)phenyl)amine (TF-6Br),has been readily synthesized in high yield through a concise Friedel-Crafts reaction from triphenylamine and 2,7-...A shape-persistent dendritic molecule,tris(4-(2,7-dibromo-9-phenyl-9-fluoren-9-yl)phenyl)amine (TF-6Br),has been readily synthesized in high yield through a concise Friedel-Crafts reaction from triphenylamine and 2,7-dibromo(9-phenyl-fluoren-9-ol).It was further employed as the key building block to achieve the synthesis of conjugated porous polymer via Sonogashira coupling with 1,4-diethynylbenzene.Under experimental reaction conditions,the resulting porous polymer shows exceptionally nanotubular morphology,which further allows for a template-free synthesis of porous carbon nanotubes via thermal treatment at high temperature.The obtained nitrogen-doped carbon nanotubes feature with an improved porosity and high surface area.展开更多
The separator with excellent mechanical and thermal properties are highly required for lithium ion batteries(LIBs).Therefore,it is crucial to develop novel nanofbrous membranes with enhanced mechanical strength and th...The separator with excellent mechanical and thermal properties are highly required for lithium ion batteries(LIBs).Therefore,it is crucial to develop novel nanofbrous membranes with enhanced mechanical strength and thermal stability.In this work,the fuorinated polyimide(FPI)was synthesized and blended with polyvinylidene fuoride(PVDF)to fabricate composite nanofbrous membranes(CNMs)via electrospinning method.Benefting from the introduction of aromatic FPI,the prepared PVDF/FPI nanofbrous membranes were endowed with enhanced mechanical strength and thermal stability.When the FPI content increased from 0 to 30 wt%,the tensile strength of composite nanofbrous membranes enhanced from 1.57 to 2.30 MPa.Moreover,there are almost no dimensional shrinkage for the CNM-30 containing 30 wt%FPI after heat treatment at 160℃ for 1 h.Furthermore,the prepared CNMs show improved electrochemical performances in comparison with neat PVDF and commercial Celgard membranes.The electrolyte uptake and ionic conductivity of the CNMs could reach to 522.4% and 1.14 ms·cm^(−1),respectively.The prepared CNMs could provide an innovative and promising approach for the development and design of high-performance separators.展开更多
In this study, cucurbit[8]uril (CB[8]) was utilized as a kind of new adsorbent to remove Pb^2+ ions from aqueous solution. With the solution pH increased from 2 to 6, the removal efficiency of adsorption increased ...In this study, cucurbit[8]uril (CB[8]) was utilized as a kind of new adsorbent to remove Pb^2+ ions from aqueous solution. With the solution pH increased from 2 to 6, the removal efficiency of adsorption increased from 55.6% to 74.5%correspondingly. The uptake of Pb^2+ increased rapidly in the initial 30 min, and then the adsorption rate became slower. The Pseudo-second order model could be used to interpret the adsorption kinetics satisfactorily; and the rate determining step in Pb^2+ adsorption onto CB[8] was the external mass transfer step. Equilibrium isotherm study reveals that the Langmuir model gave a better fitting result than Freundlich model. The maximum adsorption capacity calculated by the Langmuir model was 152.67 mg/g for 298 K, 149.70 mg/g for 313 K and 136.42 mg/g for 323 K, respectively. The adsorption is a spontaneous process of exothermic nature. The effect of the adsorbent dosage and the influences of solution pH and co-existing cations were also investigated. The CB[8] was synthesized and characterized by 1H NMR, IR, ESI-MS spectra, SEM-EDAX, Zeta-potential and BET-analysis. The adsorption mechanism was due to the coordination between CB[8] molecule and Pb^2+ ions.展开更多
Two copolymers of P1 and P2 comprising benzothiadiazole, 1,4-bis(dodecyloxy)-benzene units were synthesized by Sonogashira coupling polymerization based on ethynyl-linked 1,2,5,6-naphthalenediimide. Their thermal, o...Two copolymers of P1 and P2 comprising benzothiadiazole, 1,4-bis(dodecyloxy)-benzene units were synthesized by Sonogashira coupling polymerization based on ethynyl-linked 1,2,5,6-naphthalenediimide. Their thermal, optical, electrochemical as well as charge transport properties were studied. Bottom-gate top-contact organic field-effect transistors (OFETs) measurements of P1 and P2 thin films showed different charge transport behaviors. P1 displayed pure electron transport behaviors in OFETs with electron mobility up to 10^-3 cm^2·V-1·s^-1, while P2 exhibited hole transport features. The molecular structure analysis revealed that the structure of P1 has the acceptor-linker-acceptor' (A-L-A') characteristic, and P2 possesses the donor-linker-acceptor (D-L-A) structure feature. The results demonstrate that different molecular structures lead them to have distinct charge transport behaviors. In particular, the first pure electron transport copolymer in OFETs based on 1,2,5,6-naphthalenediimide is achieved.展开更多
基金supported by the National Natural Science Foundation of China(21766009)Program of Qingjiang Excellent Young Talents(Jiangxi University of Science and Technology)。
文摘A novel solid Bronsted-Lewis acid catalyst La-PW-SiO_(2)/SWCNTs(single-wall carbon nanotubes)was synthesized from the synergistic modification of H_(3)PW_(12)O_(40)(HPW)by single-walled carbon nanotubes functionalized with sidewall hydroxyl groups(SWCNTs–OH)and La^(3+) via sol–gel method.The freshly prepared catalyst was characterized by several methods,and the catalytic activity and stability of it were studied from the esterification of oleic acid and methanol.Results showed that the highest conversion of oleic acid was 93.1%(mass)and maintained as high as 88.7%(mass)after six cycles of La-PW-SiO_(2)/SWCNTs.The high catalytic activity and stability of La-PW-SiO_(2)/SWCNTs can be attributed to the strong electron withdrawing effect of La^(3+) on π bond of SWCNTs,because it can facilitate the formation of a large number of strong Lewis acid sites.Therefore,the reduction of catalytic activity of a solid acid catalyst due to the fact that hydration reaction of its Bronsted acid sites can be effectively reduced.La-PW-SiO_(2)/SWCNTs can be an efficient and economical catalyst,because it shows good catalytic activity and stability.
基金the National Natural Science Foundation of China(Nos.22001034 and 21804019)the Open Fund of the Jiangxi Province Key Laboratory of Synthetic Chemistry(No.JXSC202008)the Research Found of East China University of Technology(Nos.DHBK2019265,DHBK2019267,DHBK2019264)for financial support.
文摘We report an exclusively tandem C—O and C—C bond forming beyond the esterification and cyclization reaction of 2-acylbenzoic acids with alcohols to regio-and stereoselective synthesis of the(Z)-3-ylidenephthalides.The reaction uses the nontoxic,inexpensive H_(3)PMo1_(2)O_(40) as catalyst and produces water as the sole by-product,making the reaction environmentally benign and sustainable.Moreover,this reaction features an eco-friendly reaction condition,facile scalability,and easy derivatization of the products to drugs and bioactive compounds.The mechanism studies and density functional theory calculations reveal that the appropriate acid catalyst is the key to the selectivity of this transformation.
基金ProjectsupportedbytheNaturalScienceFoundationofShandongProvince (No .Y2 0 0 0B0 3)
文摘It has been found that the two-phase reactions of aqueous HCl, HOAc or H_3PO_4 with primary amine N_ 1923 in chloroform are oscillating reactions. Their power-time curves were measured by the titration microcalorimetric method, and the induction period (t_ in). The first oscillating period (t_ p.1) and the second oscillating period (t_ p.2) were determined. The apparent activating parameters and the orders of the oscillating systems were calculated and the following relationships were established: for the oscillating system of hydrochloric acid t_ in∝c 0.147_ HClexp(1.35×10 3T), t_ p.1∝c 0.241_ HCl· exp(4.33×10 3T), t_ p.2∝c 0.290_ HClexp(5.59×10 3T); for the oscillating system of acetic acid, t_ in∝c 0.883_ HOAcexp(2.32×10 3T), t_ p.1∝c 0.399_ HOAc· exp(4.50×10 3T), t_ p.2∝c 0.301_ HOAcexp(5.88×10 3T); for the oscillating system of phosphoric acid, t_ in∝c 1.14_ H_3PO_4exp(7.70×10 4T), t_ p.1∝c 1.42_ H_3PO_4exp(1.14×10 4T), t_ p.2∝c 1.47_ H_3PO_4exp(1.27×10 4T).
基金financially supported by the National Natural Science Foundation of China(21174083)the China Postdoctoral Science Foundation(2011M500767)+1 种基金the Key Program of Science and Technology Commission Foundation of Shanghai(11JC1405400)Shanghai Jiao Tong University(211 Project)
文摘A shape-persistent dendritic molecule,tris(4-(2,7-dibromo-9-phenyl-9-fluoren-9-yl)phenyl)amine (TF-6Br),has been readily synthesized in high yield through a concise Friedel-Crafts reaction from triphenylamine and 2,7-dibromo(9-phenyl-fluoren-9-ol).It was further employed as the key building block to achieve the synthesis of conjugated porous polymer via Sonogashira coupling with 1,4-diethynylbenzene.Under experimental reaction conditions,the resulting porous polymer shows exceptionally nanotubular morphology,which further allows for a template-free synthesis of porous carbon nanotubes via thermal treatment at high temperature.The obtained nitrogen-doped carbon nanotubes feature with an improved porosity and high surface area.
基金The authors gratefully acknowledge the supports from the Emergency Support and Public Safety Scientifc Research Projects of National Advanced Functional Fiber Innovation Center(2020-fx020009)The Postgraduate Innovation Foundation of Xi’an Polytechnic University(CHX2020037)Natural Science Foundation of Education Department of Shaanxi Province(21JK0657).
文摘The separator with excellent mechanical and thermal properties are highly required for lithium ion batteries(LIBs).Therefore,it is crucial to develop novel nanofbrous membranes with enhanced mechanical strength and thermal stability.In this work,the fuorinated polyimide(FPI)was synthesized and blended with polyvinylidene fuoride(PVDF)to fabricate composite nanofbrous membranes(CNMs)via electrospinning method.Benefting from the introduction of aromatic FPI,the prepared PVDF/FPI nanofbrous membranes were endowed with enhanced mechanical strength and thermal stability.When the FPI content increased from 0 to 30 wt%,the tensile strength of composite nanofbrous membranes enhanced from 1.57 to 2.30 MPa.Moreover,there are almost no dimensional shrinkage for the CNM-30 containing 30 wt%FPI after heat treatment at 160℃ for 1 h.Furthermore,the prepared CNMs show improved electrochemical performances in comparison with neat PVDF and commercial Celgard membranes.The electrolyte uptake and ionic conductivity of the CNMs could reach to 522.4% and 1.14 ms·cm^(−1),respectively.The prepared CNMs could provide an innovative and promising approach for the development and design of high-performance separators.
基金support provided by the National Nature Science Foundation of China (Nos. 51208179, 21202037)the Doctor Fund of Henan University of Technology (No. 2013BS066)
文摘In this study, cucurbit[8]uril (CB[8]) was utilized as a kind of new adsorbent to remove Pb^2+ ions from aqueous solution. With the solution pH increased from 2 to 6, the removal efficiency of adsorption increased from 55.6% to 74.5%correspondingly. The uptake of Pb^2+ increased rapidly in the initial 30 min, and then the adsorption rate became slower. The Pseudo-second order model could be used to interpret the adsorption kinetics satisfactorily; and the rate determining step in Pb^2+ adsorption onto CB[8] was the external mass transfer step. Equilibrium isotherm study reveals that the Langmuir model gave a better fitting result than Freundlich model. The maximum adsorption capacity calculated by the Langmuir model was 152.67 mg/g for 298 K, 149.70 mg/g for 313 K and 136.42 mg/g for 323 K, respectively. The adsorption is a spontaneous process of exothermic nature. The effect of the adsorbent dosage and the influences of solution pH and co-existing cations were also investigated. The CB[8] was synthesized and characterized by 1H NMR, IR, ESI-MS spectra, SEM-EDAX, Zeta-potential and BET-analysis. The adsorption mechanism was due to the coordination between CB[8] molecule and Pb^2+ ions.
基金financially supported by the National Natural Science Foundation of China(No.21674126)the"Strategic Priority Research Program"(No.XDB12010100)the Shanghai Science and Technology Committee(No.16JC1400603)
文摘Two copolymers of P1 and P2 comprising benzothiadiazole, 1,4-bis(dodecyloxy)-benzene units were synthesized by Sonogashira coupling polymerization based on ethynyl-linked 1,2,5,6-naphthalenediimide. Their thermal, optical, electrochemical as well as charge transport properties were studied. Bottom-gate top-contact organic field-effect transistors (OFETs) measurements of P1 and P2 thin films showed different charge transport behaviors. P1 displayed pure electron transport behaviors in OFETs with electron mobility up to 10^-3 cm^2·V-1·s^-1, while P2 exhibited hole transport features. The molecular structure analysis revealed that the structure of P1 has the acceptor-linker-acceptor' (A-L-A') characteristic, and P2 possesses the donor-linker-acceptor (D-L-A) structure feature. The results demonstrate that different molecular structures lead them to have distinct charge transport behaviors. In particular, the first pure electron transport copolymer in OFETs based on 1,2,5,6-naphthalenediimide is achieved.