SiO2 supported chitosan Schiff-base Palladiam catalyst was prepared and used in the Heck reaction.Effects of the molar ratio of butyl acrylate and iodobenzene,base,the molar ratio of base and ioidobenzene,reaction tem...SiO2 supported chitosan Schiff-base Palladiam catalyst was prepared and used in the Heck reaction.Effects of the molar ratio of butyl acrylate and iodobenzene,base,the molar ratio of base and ioidobenzene,reaction temperature,reaction time and the amount of catalyst used on the yield were investigated by using orthogonal designation method.The order of the effect of the above factors is:base>the amoun t of catalyst>reaction temperature>the molar ratio of base and and iodobenzene>react ion time>the molar ratio of butyl acrylate and iodobenzene.Under the optimal reaction conditions:2 mmol iodobenzene,1.5∶1 molar ratio of butyl acrylate and iodobenzene,1.8∶1 molar ratio of（n-Bu）3N and iodobenzene,0.07g catalyst,4mLODMF,140℃for 4 hours,99.9%yield of buty l cinnamate can be achieved,and the catalyst could be reused for 12 times without the loss of activity.It can also catalyze the coupling reaction of the other substrates in high yields.展开更多
Stable integration of hydrogel implants with host tissues is of critical importance to cartilage tissue engineering.Designing and fabricating hydrogels with high adhesive strength,stability and regeneration potential ...Stable integration of hydrogel implants with host tissues is of critical importance to cartilage tissue engineering.Designing and fabricating hydrogels with high adhesive strength,stability and regeneration potential are major challenges to be overcome.This study fabricated injectable adhesive hyaluronic acid(HA)hydrogel modified by aldehyde groups and methacrylate(AHAMA)on the polysaccharide backbone with multiple anchoring mechanisms(amide bond through the dynamic Schiff base reaction,hydrogen bond and physical interpenetration).AHAMA hydrogel exhibited significantly improved durability and stability within a humid environment(at least 7 days),together with higher adhesive strength(43 KPa to skin and 52 KPa to glass),as compared to commercial fibrin glue(nearly 10 KPa)and HAMA hydrogel(nearly 20 KPa).The results showed that AHAMA hydrogel was biocompatible and could be easily and rapidly prepared in situ.In vitro cell culture experiments showed that AHAMA hydrogel could enhance proliferation(1.2-folds after 3 days)and migration(1.5-folds after 12 h)of bone marrow stem cells(BMSCs),as compared to cells cultured in a culture dish.Furthermore,in a rat osteochondral defect model,implanted AHAMA hydrogel significantly promoted integration between neo-cartilage and host tissues,and significantly improved cartilage regeneration(modified O’Driscoll histological scores of 16.0±4.1 and 18.3±4.6 after 4 and 12-weeks of post-implantation in AHAMA groups respectively,12.0±2.7 and 12.2±2.8 respectively in HAMA groups,9.8±2.4 and 11.5±2.1 respectively in untreated groups).Hence,AHAMA hydrogel is a promising adhesive biomaterial for clinical cartilage regeneration and other biomedical applications.展开更多
Three new cobalt complexes were synthesized by solid-state reaction at room temperature. It was found that one mole of complex reacted with two moles of oxygen at room temperature. And the oxygenated complexes [Co...Three new cobalt complexes were synthesized by solid-state reaction at room temperature. It was found that one mole of complex reacted with two moles of oxygen at room temperature. And the oxygenated complexes [Co·(L1)2·2O2](NO3)2·2H2O (L1=N,N′-bis(4-hydroxyl-3-methoxy-benzyl)-triethylenetetramine), [Co·(L2)2·2O2](NO3)2 ·2H2O (L2=N,N′-bis(4-hydroxyl-benzyl)-triethylenetetramine) and [Co·L3·2O2](NO3)2·2H2O (L3=N,N′-bis(2-hydroxyl-benzyl)-triethylenetetramine) were obtained and characterized by elemental analysis, IR spectra, 1H NMR, TG/DTA, UV-Vis and molar conductance. The coordinated oxygen contents in the oxygenated complex were also determined by weight method. It was found that one O2 molecule coordinated to the Co ion and formed superoxo type oxygenated complex.展开更多
Supramolecular self-assembly,an important strategy in nanotechnology,has been widely studied in the past two decades.In this review,we have introduced the recent progress on construction of two-dimensional(2D)nanostru...Supramolecular self-assembly,an important strategy in nanotechnology,has been widely studied in the past two decades.In this review,we have introduced the recent progress on construction of two-dimensional(2D)nanostructures by host-guest supramolecular chemistry at solid-liquid interface,and the interactions between the host assembly and the guest molecules are the major concerns.At first,the hydrogen bonds connected hybrid structures are discussed.And then we have paid a close attention on the surface-confined condensation reactions that has flourished recently in direct preparing novel nanostructures with increasing structural complexity.In the end,the cavity confinement of the 2D supramolecular host-guest architectures has been studied.On the basis of the above-mentioned interactions,a group of functional hybrid structures have been prepared.Notably,scanning tunneling microscopy(STM),a unique technique to probe the surface morphology and information at the single molecule level,has been used to probe the formed structures on highly oriented pyrolytic graphite(HOPG)surface.展开更多
文摘SiO2 supported chitosan Schiff-base Palladiam catalyst was prepared and used in the Heck reaction.Effects of the molar ratio of butyl acrylate and iodobenzene,base,the molar ratio of base and ioidobenzene,reaction temperature,reaction time and the amount of catalyst used on the yield were investigated by using orthogonal designation method.The order of the effect of the above factors is:base>the amoun t of catalyst>reaction temperature>the molar ratio of base and and iodobenzene>react ion time>the molar ratio of butyl acrylate and iodobenzene.Under the optimal reaction conditions:2 mmol iodobenzene,1.5∶1 molar ratio of butyl acrylate and iodobenzene,1.8∶1 molar ratio of（n-Bu）3N and iodobenzene,0.07g catalyst,4mLODMF,140℃for 4 hours,99.9%yield of buty l cinnamate can be achieved,and the catalyst could be reused for 12 times without the loss of activity.It can also catalyze the coupling reaction of the other substrates in high yields.
基金This work was supported by the National Natural Science Foundation of China grant(81772334)Peking University Medicine Seed Fund for Interdisciplinary Research(BMU2018ME001).
文摘Stable integration of hydrogel implants with host tissues is of critical importance to cartilage tissue engineering.Designing and fabricating hydrogels with high adhesive strength,stability and regeneration potential are major challenges to be overcome.This study fabricated injectable adhesive hyaluronic acid(HA)hydrogel modified by aldehyde groups and methacrylate(AHAMA)on the polysaccharide backbone with multiple anchoring mechanisms(amide bond through the dynamic Schiff base reaction,hydrogen bond and physical interpenetration).AHAMA hydrogel exhibited significantly improved durability and stability within a humid environment(at least 7 days),together with higher adhesive strength(43 KPa to skin and 52 KPa to glass),as compared to commercial fibrin glue(nearly 10 KPa)and HAMA hydrogel(nearly 20 KPa).The results showed that AHAMA hydrogel was biocompatible and could be easily and rapidly prepared in situ.In vitro cell culture experiments showed that AHAMA hydrogel could enhance proliferation(1.2-folds after 3 days)and migration(1.5-folds after 12 h)of bone marrow stem cells(BMSCs),as compared to cells cultured in a culture dish.Furthermore,in a rat osteochondral defect model,implanted AHAMA hydrogel significantly promoted integration between neo-cartilage and host tissues,and significantly improved cartilage regeneration(modified O’Driscoll histological scores of 16.0±4.1 and 18.3±4.6 after 4 and 12-weeks of post-implantation in AHAMA groups respectively,12.0±2.7 and 12.2±2.8 respectively in HAMA groups,9.8±2.4 and 11.5±2.1 respectively in untreated groups).Hence,AHAMA hydrogel is a promising adhesive biomaterial for clinical cartilage regeneration and other biomedical applications.
文摘Three new cobalt complexes were synthesized by solid-state reaction at room temperature. It was found that one mole of complex reacted with two moles of oxygen at room temperature. And the oxygenated complexes [Co·(L1)2·2O2](NO3)2·2H2O (L1=N,N′-bis(4-hydroxyl-3-methoxy-benzyl)-triethylenetetramine), [Co·(L2)2·2O2](NO3)2 ·2H2O (L2=N,N′-bis(4-hydroxyl-benzyl)-triethylenetetramine) and [Co·L3·2O2](NO3)2·2H2O (L3=N,N′-bis(2-hydroxyl-benzyl)-triethylenetetramine) were obtained and characterized by elemental analysis, IR spectra, 1H NMR, TG/DTA, UV-Vis and molar conductance. The coordinated oxygen contents in the oxygenated complex were also determined by weight method. It was found that one O2 molecule coordinated to the Co ion and formed superoxo type oxygenated complex.
基金supports from the National Basic Research Program of China(2011CB932303,2013CB934200)the National Natural Science Foundation of China(21073048,51173031,91127043)are also gratefully acknowledged
文摘Supramolecular self-assembly,an important strategy in nanotechnology,has been widely studied in the past two decades.In this review,we have introduced the recent progress on construction of two-dimensional(2D)nanostructures by host-guest supramolecular chemistry at solid-liquid interface,and the interactions between the host assembly and the guest molecules are the major concerns.At first,the hydrogen bonds connected hybrid structures are discussed.And then we have paid a close attention on the surface-confined condensation reactions that has flourished recently in direct preparing novel nanostructures with increasing structural complexity.In the end,the cavity confinement of the 2D supramolecular host-guest architectures has been studied.On the basis of the above-mentioned interactions,a group of functional hybrid structures have been prepared.Notably,scanning tunneling microscopy(STM),a unique technique to probe the surface morphology and information at the single molecule level,has been used to probe the formed structures on highly oriented pyrolytic graphite(HOPG)surface.
