This study investigates the removal of Congo Red dye from aqueous solution using functionalized generation 3.0 and 5.0 polyamidoamine dendrimer-silica gel composite (G-3PS, G-5PS). Fourier Transform-Infra Red spectros...This study investigates the removal of Congo Red dye from aqueous solution using functionalized generation 3.0 and 5.0 polyamidoamine dendrimer-silica gel composite (G-3PS, G-5PS). Fourier Transform-Infra Red spectroscopy, Brunauer Emmett and Teller, Thermo Gravimetric Analysis, pH at point of zero charge, and scanning electron microscopy measurements have been applied to characterize the synthetic nanohybrid composite, these techniques revealed the successful functionalization of both dendrimer molecules and subsequent immobilization onto silica gel. The implications of varying adsorption parameters such as contact time, initial concentration of adsorbate, temperature and pH on both composites were studied. Experimental data obtained from batch adsorption processes were fitted into two equilibrium isotherms (Langmuir and Freundlich) and 3 kinetic models (Pseudo-First-Order, Pseudo-Second-Order, Intra Particle Diffusion). Adsorption mechanism was mainly governed by film diffusion due to electrostatic interactions between the functionalized dendrimer surface and Congo Red molecules. Thermodynamic parameters illustrate that the adsorption is endothermic and spontaneous. Findings suggest the Nanocomposites (G-3PS and G-5PS) are good adsorbents for the removal of Congo Red dye from aqueous solutions.展开更多
Due to the special viscoelastic property, traditional rubber with high performance has been widely used in human life and production. However, it is challenging to improve the damping property without sacrificing the ...Due to the special viscoelastic property, traditional rubber with high performance has been widely used in human life and production. However, it is challenging to improve the damping property without sacrificing the extensibility. In this work, a novel type of second-generation polyurethane dendrimer terminated with pyridine(G2-Py) was synthesized by using thiolactone chemistry and subsequently complexed with Zn ions. The structure and morphology of G2-Py were characterized. G2-Py-Zn2+was then mixed with chlorinated butyl rubber(CIIR) by a two-roll mill. A series of CIIR/G2-Py-Zn2+elastomers were obtained through vulcanization. CIIR/G2-Py-Zn2+elastomers could achieve high stretchability(a strain of ~1035%), high mechanical strength(a tensile stress of 7.64 MPa). This was benefitted from the friction between G2-Py and CIIR as well as variety of non-covalent bonds provided by G2-Py-Zn2+,which can dissipate energy to further improve the strength and extensibility. The coordination of Zn2+-pyridine was confirmed by Fourier transform infrared spectroscopy, stress relaxation and cycle tensile test. To further investigate the morphology and damping properties of the elastomers, scanning electron microscopy and dynamic mechanical analysis were performed. CIIR-5 showed the best damping performance with higher tan δ_(max) and wider effective damping temperatures. Therefore, this dendrimer modification technology provides wider applications for CIIR elastomers in daily life.展开更多
Topological indices(TIs)have been practiced for distinct wide-ranging physicochemical applications,especially used to characterize and model the chemical structures of various molecular compounds such as dendrimers,na...Topological indices(TIs)have been practiced for distinct wide-ranging physicochemical applications,especially used to characterize and model the chemical structures of various molecular compounds such as dendrimers,nanotubes and neural networks with respect to their certain properties such as solubility,chemical stability and low cytotoxicity.Dendrimers are prolonged artificially synthesized or amalgamated natural macromolecules with a sequential layer of branches enclosing a central core.A present-day trend in mathematical and computational chemistry is the characterization of molecular structure by applying topological approaches,including numerical graph invariants.Among topological descriptors,Zagreb connection indices(ZCIs)have much importance.This manuscript involves the establishment of general results to calculate ZCIs,namely first ZCI(FZCI),second ZCI(SZCI),third ZCI(TZCI),modified FZCI,modified SZCI and modified TZCI of two special types of dendrimers nanostars,namely,poly propylene imine octamin(PPIO)dendrimer and poly(propyl)ether imine(PPEtIm)dendrimer.Furthermore,we provide the numerical and graphical comparative analysis of our calculated results for both types of dendrimers with each other.展开更多
Oxidation of cyclohexene under 1 atmospheric pressure of molecular oxygen at 70C in the absence of solvent catalyzed by PAMAM-SA-M (Where PAMAM = polyamidoamine; SA = salicyaldehyde; M = metal ions Fe3+, Co2+, Ni2+, M...Oxidation of cyclohexene under 1 atmospheric pressure of molecular oxygen at 70C in the absence of solvent catalyzed by PAMAM-SA-M (Where PAMAM = polyamidoamine; SA = salicyaldehyde; M = metal ions Fe3+, Co2+, Ni2+, Mn2+, Cu2+, Zn2+, respectively) dendrimers, afforded 2-cyclohexen-1-ol 1, 2-cyclohexen-1-one 2, 7-oxabicyclo [4,1,0] heptane 3 and 7-oxabicyl [4,1,0] heptan-2-one 4 as the major products. The factors that affect this reaction are also discussed.展开更多
A new fourth-generation poly(propylene imine) dendrimer(G4-M) containing 32 triolefinic 15-membered macrocycles on the surfaces has been synthesized. The bimetallic Ru Rh dendrimer-stabilized nanoparticles(DSNs) were ...A new fourth-generation poly(propylene imine) dendrimer(G4-M) containing 32 triolefinic 15-membered macrocycles on the surfaces has been synthesized. The bimetallic Ru Rh dendrimer-stabilized nanoparticles(DSNs) were first prepared within G4-M by a co-complexation route. The new G4-M dendrimer has been characterized by 1H nuclear magnetic resonance, infrared radiation, and elemental analysis.The dendrimer-stabilized bimetallic ions and reduction courses were analyzed by UV-vis spectroscopy. Highresolution transmission electron microscopy and energy dispersive spectrometer were used to characterize the bimetallic nanoparticle size, size distribution, and particle morphology. The Ru Rh bimetallic DSNs showed high catalytic activity for the hydrogenation of nitrile-butadiene rubber.展开更多
A convenient synthesis and theoretical study of five CCK-functional dendrimers is described. The dendritic cores were linked with the CCK（Trp-Met-Asp（OBn）-PheNH2） fragment by forming amide bonds to give five targe...A convenient synthesis and theoretical study of five CCK-functional dendrimers is described. The dendritic cores were linked with the CCK（Trp-Met-Asp（OBn）-PheNH2） fragment by forming amide bonds to give five target molecules. The structures of CCK-functional dendrimers were characterized by NMR, MS spectrum and predicted using molecular mechanics and PM3 semi- empirical molecular orbital theory.展开更多
Carbosilane dendrimers with p-bromophenyl core were synthesized by alternating Grignard and hydrosilylation reaction. And the α-naphthalenyl was connected to the core by the Suzuki coupling reaction. A new carbosilan...Carbosilane dendrimers with p-bromophenyl core were synthesized by alternating Grignard and hydrosilylation reaction. And the α-naphthalenyl was connected to the core by the Suzuki coupling reaction. A new carbosilane dendrimer with big π-conjugated structure [4-（naphthalen-l-yl）phenyl core] was given. It shows Suzuki coupling reaction is an effective and powerful core-functionalization method and the satisfactory result can be obtained through prolonging the reaction time with the increase of the generation of dendrimer.展开更多
Carbosilane dendrimers with 4-bromo-N,N-dimethylaniline as end groups were synthesized from methyltfichlorosilane, aUyl chloride, magnesium and 4-bromo-N,N-dimethylaniline. All compounds were characterized by ^1H NMR,...Carbosilane dendrimers with 4-bromo-N,N-dimethylaniline as end groups were synthesized from methyltfichlorosilane, aUyl chloride, magnesium and 4-bromo-N,N-dimethylaniline. All compounds were characterized by ^1H NMR, IR, MS.展开更多
A novel quaternary ammonium chitosan hydrogel modified by poly（amidoamine）（PAMAM） dendrimer was prepared by using glutaraldehyde as a cross-linker. The hydrogel was characterized by Fourier transform infrared spec...A novel quaternary ammonium chitosan hydrogel modified by poly（amidoamine）（PAMAM） dendrimer was prepared by using glutaraldehyde as a cross-linker. The hydrogel was characterized by Fourier transform infrared spectroscopy（FTIR） and scanning electron microscopy（SEM）. The results confirmed its highly porous three-dimensional network structure. The swelling test of hydrogel proved that it had excellent swelling and p H-sensitive properties. The increasing PAMAM content or quaternization degree led to the increase in swelling properties. And the hydrogel with lower cross-linking agent concentration or quaternary ammonium chitosan concentration exhibited better swelling properties. The antibacterial results indicated that with the increase in the PAMAM content, quaternary ammonium chitosan concentration or cross-linking agent concentration, the hydrogels showed better antibacterial activities against both Staphylococcus aureus（S. aureus） and Escherichia coli（E. coli）. Thus, the hydrogel could serve as a promising antibacterial material in the future.展开更多
The interaction of biotinylated G4 poly(amidoamine) (PAMAM) dendrimer conjugates and G4 PAMAM dendrimers with in vitro models of the blood brain barrier (BBB) was evaluated using Langmuir Blodgett monolayer techniques...The interaction of biotinylated G4 poly(amidoamine) (PAMAM) dendrimer conjugates and G4 PAMAM dendrimers with in vitro models of the blood brain barrier (BBB) was evaluated using Langmuir Blodgett monolayer techniques, atomic force microscopy (AFM) and lactate dehydrogenase measures of cell membrane toxicity. Results indicate that both G4 and G4 biotinylated PAMAM dendrimers disrupt the composition of the liquid condensed (LC) and liquid expanded (LE) phases of the 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) lipid monolayer. The disruption is concentration dependent and more marked for G4 biotinylated PAMAMs. Lactate dehydrogenase (LDH) assays using endothelial cell culture models of the BBB indicate that biotinylation results in higher levels of toxicity than non-biotinylation. This approach provides valuable information to assess nanoparticle toxicity for drug delivery to the brain.展开更多
文摘This study investigates the removal of Congo Red dye from aqueous solution using functionalized generation 3.0 and 5.0 polyamidoamine dendrimer-silica gel composite (G-3PS, G-5PS). Fourier Transform-Infra Red spectroscopy, Brunauer Emmett and Teller, Thermo Gravimetric Analysis, pH at point of zero charge, and scanning electron microscopy measurements have been applied to characterize the synthetic nanohybrid composite, these techniques revealed the successful functionalization of both dendrimer molecules and subsequent immobilization onto silica gel. The implications of varying adsorption parameters such as contact time, initial concentration of adsorbate, temperature and pH on both composites were studied. Experimental data obtained from batch adsorption processes were fitted into two equilibrium isotherms (Langmuir and Freundlich) and 3 kinetic models (Pseudo-First-Order, Pseudo-Second-Order, Intra Particle Diffusion). Adsorption mechanism was mainly governed by film diffusion due to electrostatic interactions between the functionalized dendrimer surface and Congo Red molecules. Thermodynamic parameters illustrate that the adsorption is endothermic and spontaneous. Findings suggest the Nanocomposites (G-3PS and G-5PS) are good adsorbents for the removal of Congo Red dye from aqueous solutions.
基金supported by the National Natural Science Fundation of China((51873103)Capacity Building Project of Some Local Colleges and Universities in Shanghai(17030501200)+1 种基金Talent Program of Shanghai University of Engineering Science(2017RC422017)Postgraduate Research and Innovation Project of Shanghai University of Engineering Science(0234-E3-0903-19-01367).
文摘Due to the special viscoelastic property, traditional rubber with high performance has been widely used in human life and production. However, it is challenging to improve the damping property without sacrificing the extensibility. In this work, a novel type of second-generation polyurethane dendrimer terminated with pyridine(G2-Py) was synthesized by using thiolactone chemistry and subsequently complexed with Zn ions. The structure and morphology of G2-Py were characterized. G2-Py-Zn2+was then mixed with chlorinated butyl rubber(CIIR) by a two-roll mill. A series of CIIR/G2-Py-Zn2+elastomers were obtained through vulcanization. CIIR/G2-Py-Zn2+elastomers could achieve high stretchability(a strain of ~1035%), high mechanical strength(a tensile stress of 7.64 MPa). This was benefitted from the friction between G2-Py and CIIR as well as variety of non-covalent bonds provided by G2-Py-Zn2+,which can dissipate energy to further improve the strength and extensibility. The coordination of Zn2+-pyridine was confirmed by Fourier transform infrared spectroscopy, stress relaxation and cycle tensile test. To further investigate the morphology and damping properties of the elastomers, scanning electron microscopy and dynamic mechanical analysis were performed. CIIR-5 showed the best damping performance with higher tan δ_(max) and wider effective damping temperatures. Therefore, this dendrimer modification technology provides wider applications for CIIR elastomers in daily life.
文摘Topological indices(TIs)have been practiced for distinct wide-ranging physicochemical applications,especially used to characterize and model the chemical structures of various molecular compounds such as dendrimers,nanotubes and neural networks with respect to their certain properties such as solubility,chemical stability and low cytotoxicity.Dendrimers are prolonged artificially synthesized or amalgamated natural macromolecules with a sequential layer of branches enclosing a central core.A present-day trend in mathematical and computational chemistry is the characterization of molecular structure by applying topological approaches,including numerical graph invariants.Among topological descriptors,Zagreb connection indices(ZCIs)have much importance.This manuscript involves the establishment of general results to calculate ZCIs,namely first ZCI(FZCI),second ZCI(SZCI),third ZCI(TZCI),modified FZCI,modified SZCI and modified TZCI of two special types of dendrimers nanostars,namely,poly propylene imine octamin(PPIO)dendrimer and poly(propyl)ether imine(PPEtIm)dendrimer.Furthermore,we provide the numerical and graphical comparative analysis of our calculated results for both types of dendrimers with each other.
文摘Oxidation of cyclohexene under 1 atmospheric pressure of molecular oxygen at 70C in the absence of solvent catalyzed by PAMAM-SA-M (Where PAMAM = polyamidoamine; SA = salicyaldehyde; M = metal ions Fe3+, Co2+, Ni2+, Mn2+, Cu2+, Zn2+, respectively) dendrimers, afforded 2-cyclohexen-1-ol 1, 2-cyclohexen-1-one 2, 7-oxabicyclo [4,1,0] heptane 3 and 7-oxabicyl [4,1,0] heptan-2-one 4 as the major products. The factors that affect this reaction are also discussed.
基金supported financially by the National Natural Science Foundation of China (Project No.51273071)
文摘A new fourth-generation poly(propylene imine) dendrimer(G4-M) containing 32 triolefinic 15-membered macrocycles on the surfaces has been synthesized. The bimetallic Ru Rh dendrimer-stabilized nanoparticles(DSNs) were first prepared within G4-M by a co-complexation route. The new G4-M dendrimer has been characterized by 1H nuclear magnetic resonance, infrared radiation, and elemental analysis.The dendrimer-stabilized bimetallic ions and reduction courses were analyzed by UV-vis spectroscopy. Highresolution transmission electron microscopy and energy dispersive spectrometer were used to characterize the bimetallic nanoparticle size, size distribution, and particle morphology. The Ru Rh bimetallic DSNs showed high catalytic activity for the hydrogenation of nitrile-butadiene rubber.
文摘A convenient synthesis and theoretical study of five CCK-functional dendrimers is described. The dendritic cores were linked with the CCK（Trp-Met-Asp（OBn）-PheNH2） fragment by forming amide bonds to give five target molecules. The structures of CCK-functional dendrimers were characterized by NMR, MS spectrum and predicted using molecular mechanics and PM3 semi- empirical molecular orbital theory.
文摘Carbosilane dendrimers with p-bromophenyl core were synthesized by alternating Grignard and hydrosilylation reaction. And the α-naphthalenyl was connected to the core by the Suzuki coupling reaction. A new carbosilane dendrimer with big π-conjugated structure [4-（naphthalen-l-yl）phenyl core] was given. It shows Suzuki coupling reaction is an effective and powerful core-functionalization method and the satisfactory result can be obtained through prolonging the reaction time with the increase of the generation of dendrimer.
基金supported by the National Natural Science Foundation of China(No.20574043)the Natural Science Foundation of Shandong Province of China(No.Y2003B01).
文摘Carbosilane dendrimers with 4-bromo-N,N-dimethylaniline as end groups were synthesized from methyltfichlorosilane, aUyl chloride, magnesium and 4-bromo-N,N-dimethylaniline. All compounds were characterized by ^1H NMR, IR, MS.
基金Funded by the National Natural Science Foundation of China(Nos.51303145,51273156,51373130)
文摘A novel quaternary ammonium chitosan hydrogel modified by poly（amidoamine）（PAMAM） dendrimer was prepared by using glutaraldehyde as a cross-linker. The hydrogel was characterized by Fourier transform infrared spectroscopy（FTIR） and scanning electron microscopy（SEM）. The results confirmed its highly porous three-dimensional network structure. The swelling test of hydrogel proved that it had excellent swelling and p H-sensitive properties. The increasing PAMAM content or quaternization degree led to the increase in swelling properties. And the hydrogel with lower cross-linking agent concentration or quaternary ammonium chitosan concentration exhibited better swelling properties. The antibacterial results indicated that with the increase in the PAMAM content, quaternary ammonium chitosan concentration or cross-linking agent concentration, the hydrogels showed better antibacterial activities against both Staphylococcus aureus（S. aureus） and Escherichia coli（E. coli）. Thus, the hydrogel could serve as a promising antibacterial material in the future.
文摘The interaction of biotinylated G4 poly(amidoamine) (PAMAM) dendrimer conjugates and G4 PAMAM dendrimers with in vitro models of the blood brain barrier (BBB) was evaluated using Langmuir Blodgett monolayer techniques, atomic force microscopy (AFM) and lactate dehydrogenase measures of cell membrane toxicity. Results indicate that both G4 and G4 biotinylated PAMAM dendrimers disrupt the composition of the liquid condensed (LC) and liquid expanded (LE) phases of the 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) lipid monolayer. The disruption is concentration dependent and more marked for G4 biotinylated PAMAMs. Lactate dehydrogenase (LDH) assays using endothelial cell culture models of the BBB indicate that biotinylation results in higher levels of toxicity than non-biotinylation. This approach provides valuable information to assess nanoparticle toxicity for drug delivery to the brain.
