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
This paper described the first example of polyamidoamine dendrimers ester(PAMAM) used as a gel electrolyte with a short-chain polyethylene glycol (MPEG-400) as aplasticizer. The polymer films are solid and sticky. Bac...This paper described the first example of polyamidoamine dendrimers ester(PAMAM) used as a gel electrolyte with a short-chain polyethylene glycol (MPEG-400) as aplasticizer. The polymer films are solid and sticky. Background cyclic voltammetry (CV) shows apotential window between +0.7 and -0.7 V vs. Ag/AgCl. The voltammetry of ferrocene and7,7,8,8-tetracyanoquinodimethane (TCNQ) indicates that diffusion coefficients are in the range of10^(-8) -10^(-9) cm^2/s. Ionic conductivities are approximately 10^(-6) S/cm. Similar films usingdimethyl sulfoxide (DMSO) as a plasticizer instead of MPEG-400 have demonstrated ionicconductivities of 10^(-4) S/cm and reversible voltammetry. However, UV spectropho-tometry shows that70% of the DMSO is lost under vacuum, indicating the difficulty in quantifying the DMSO contentwhen exposed to vacuum.展开更多
Peroxide-cured high-temperature vulcanized (HTV) silicone rubber was prepared by using allyl-capped carbosilane dendrimers, in which the core molecule is Si(CHaCH=CH2)4, as the cross-linker. It showed that this ki...Peroxide-cured high-temperature vulcanized (HTV) silicone rubber was prepared by using allyl-capped carbosilane dendrimers, in which the core molecule is Si(CHaCH=CH2)4, as the cross-linker. It showed that this kind of allyl-capped carbosilane dendrimer improved the mechanical properties of silicone rubber.展开更多
This paper describes the facile synthesis and characterization of novel dendrimers bearing 9 and 12 CCK peptide fragments on the surface by a convergent method. The structures of dendrimers are characterized by NMR an...This paper describes the facile synthesis and characterization of novel dendrimers bearing 9 and 12 CCK peptide fragments on the surface by a convergent method. The structures of dendrimers are characterized by NMR and MS spectrum.展开更多
A general procedure for surface modification of nano-alumina using N, N'-dicyclohexyl- carbodiimide (DCC) mediated amidation is reported. Aliphatic and aromatic carboxylic acids reacted smoothly with nano-alumina p...A general procedure for surface modification of nano-alumina using N, N'-dicyclohexyl- carbodiimide (DCC) mediated amidation is reported. Aliphatic and aromatic carboxylic acids reacted smoothly with nano-alumina pretreated with 3-aminopropyltriethoxysilane in the presence of DCC, giving modified aluminas having organic surfaces. The grafted aluminas have been characterized qualitatively by FT-IR or ^13C CPMAS NMR spectroscopy, and quantitatively by thermogravimetric analysis and elemental analysis. The procedure was applied to polyether dendrons bearing carboxyl groups at the focal points, giving successful grafting of dendrimers onto nano-alumina.展开更多
New functional dendrimers bearing 4, 8 and 16 axial chiral units on their surface were synthesized from achiral PAMAM dendrimers and axial chiral (R)-BINOL derivative.
Some novel peptide dendrimers bearing four amino acids, GD and RGD peptides on their surface were synthesized from tetrakis[(carboxyethoxy)methyl]-methane using DCC method.
Fluorinated polyether dendritic sectors 4, 7 and 10 from the first to the third generations, respectively, were prepared by a convergent approach from readily available pentafluorophenol, phloroglucinol and 1,3-dibrom...Fluorinated polyether dendritic sectors 4, 7 and 10 from the first to the third generations, respectively, were prepared by a convergent approach from readily available pentafluorophenol, phloroglucinol and 1,3-dibromopropane. These dendritic sectors have good solubility properties and are stable in both acidic and basic media. Hence they are useful dendritic building blocks for the preparation of functional dendrimers.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 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
Polysiloxane was a good solvent for hydrosilation reaction of carbosilane dendrimers with pentafluorophenyl core and HSiMeE(CH2)3C6F5. A new kind of dendrimer with both pentafluorophenyl core and terminal groups was...Polysiloxane was a good solvent for hydrosilation reaction of carbosilane dendrimers with pentafluorophenyl core and HSiMeE(CH2)3C6F5. A new kind of dendrimer with both pentafluorophenyl core and terminal groups was synthesized. The studies showed that with the increase of fluorination, the viscosity values of carbosilane dendrimers decreased.展开更多
A series of novel pentaerythritol-based carbosilane dendrimers have been synthesized. Using pentaerythritol-based tetraallyl ether as core molecule, the dendrimers have been prepared up to the third generation with 10...A series of novel pentaerythritol-based carbosilane dendrimers have been synthesized. Using pentaerythritol-based tetraallyl ether as core molecule, the dendrimers have been prepared up to the third generation with 108 allyl groups on the periphery by alternate allylation-hydro- silylation approach.展开更多
The preparation of carbosilane dendrimers with cores of myo-inositol and the outmost periphery groups of allyl groups has been reported. By using alternate hydrosilylation and alkenylation reactions, the dendrimer ha...The preparation of carbosilane dendrimers with cores of myo-inositol and the outmost periphery groups of allyl groups has been reported. By using alternate hydrosilylation and alkenylation reactions, the dendrimer have been carried up to the third generation with 48 allyl groups on the periphery.展开更多
First to third-generation calix[4] resorcinarene core dendrimers, compounds 4a, 4b, 7a, 7b, 10a and 10b, were prepared via the divergent method in seven steps with the corresponding tetraphenyl- and tetra (hydroxyphe...First to third-generation calix[4] resorcinarene core dendrimers, compounds 4a, 4b, 7a, 7b, 10a and 10b, were prepared via the divergent method in seven steps with the corresponding tetraphenyl- and tetra (hydroxyphenyl) calix[4] resorcinarenes (compounds 1a, 1b) as the starting material. The repeat units of the polyamidoamines of these dendrimers were obtained by the ammonolysis of ethyl calixarylacetates 2a and 2b with 1,3-diaminopropane, that is, amide derivatives with terminal amino groups, which in turn reacted with ethyl acrylate to give a higher generation of ester derivatives. The structures of these dendrimers were characterized by IR, ^1H and ^13C NMR spoctrometries. The crystal structure of compound 2b with 12 ethoxycarbonylmethoxy groups was determined by X-ray analysis.展开更多
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.
基金This work was financially supported by the National Natural Science Foundation of China (No. 29875018) the Natural Science Foundation of Gansu Province (No. ZS991-A25-008-Z)the Doctorate Foundation of Northwestern Politech-nical University (No. CX200
文摘This paper described the first example of polyamidoamine dendrimers ester(PAMAM) used as a gel electrolyte with a short-chain polyethylene glycol (MPEG-400) as aplasticizer. The polymer films are solid and sticky. Background cyclic voltammetry (CV) shows apotential window between +0.7 and -0.7 V vs. Ag/AgCl. The voltammetry of ferrocene and7,7,8,8-tetracyanoquinodimethane (TCNQ) indicates that diffusion coefficients are in the range of10^(-8) -10^(-9) cm^2/s. Ionic conductivities are approximately 10^(-6) S/cm. Similar films usingdimethyl sulfoxide (DMSO) as a plasticizer instead of MPEG-400 have demonstrated ionicconductivities of 10^(-4) S/cm and reversible voltammetry. However, UV spectropho-tometry shows that70% of the DMSO is lost under vacuum, indicating the difficulty in quantifying the DMSO contentwhen exposed to vacuum.
文摘Peroxide-cured high-temperature vulcanized (HTV) silicone rubber was prepared by using allyl-capped carbosilane dendrimers, in which the core molecule is Si(CHaCH=CH2)4, as the cross-linker. It showed that this kind of allyl-capped carbosilane dendrimer improved the mechanical properties of silicone rubber.
基金support of National Natural Science Foundation of China(No.20472055).
文摘This paper describes the facile synthesis and characterization of novel dendrimers bearing 9 and 12 CCK peptide fragments on the surface by a convergent method. The structures of dendrimers are characterized by NMR and MS spectrum.
文摘A general procedure for surface modification of nano-alumina using N, N'-dicyclohexyl- carbodiimide (DCC) mediated amidation is reported. Aliphatic and aromatic carboxylic acids reacted smoothly with nano-alumina pretreated with 3-aminopropyltriethoxysilane in the presence of DCC, giving modified aluminas having organic surfaces. The grafted aluminas have been characterized qualitatively by FT-IR or ^13C CPMAS NMR spectroscopy, and quantitatively by thermogravimetric analysis and elemental analysis. The procedure was applied to polyether dendrons bearing carboxyl groups at the focal points, giving successful grafting of dendrimers onto nano-alumina.
文摘New functional dendrimers bearing 4, 8 and 16 axial chiral units on their surface were synthesized from achiral PAMAM dendrimers and axial chiral (R)-BINOL derivative.
基金the financial support of the National Natural Science Foundation of China (Project No. 20472055).
文摘Some novel peptide dendrimers bearing four amino acids, GD and RGD peptides on their surface were synthesized from tetrakis[(carboxyethoxy)methyl]-methane using DCC method.
文摘Fluorinated polyether dendritic sectors 4, 7 and 10 from the first to the third generations, respectively, were prepared by a convergent approach from readily available pentafluorophenol, phloroglucinol and 1,3-dibromopropane. These dendritic sectors have good solubility properties and are stable in both acidic and basic media. Hence they are useful dendritic building blocks for the preparation of functional dendrimers.
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.
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supported by the National Natural Science Foundation of China(No 50503010).
文摘Polysiloxane was a good solvent for hydrosilation reaction of carbosilane dendrimers with pentafluorophenyl core and HSiMeE(CH2)3C6F5. A new kind of dendrimer with both pentafluorophenyl core and terminal groups was synthesized. The studies showed that with the increase of fluorination, the viscosity values of carbosilane dendrimers decreased.
基金This work was supported by the National Natural Science Foundation of China(No.29874020,59573029).
文摘A series of novel pentaerythritol-based carbosilane dendrimers have been synthesized. Using pentaerythritol-based tetraallyl ether as core molecule, the dendrimers have been prepared up to the third generation with 108 allyl groups on the periphery by alternate allylation-hydro- silylation approach.
基金We are grateful to the National Natural Science Foundation of China for financial support(No.29874020).
文摘The preparation of carbosilane dendrimers with cores of myo-inositol and the outmost periphery groups of allyl groups has been reported. By using alternate hydrosilylation and alkenylation reactions, the dendrimer have been carried up to the third generation with 48 allyl groups on the periphery.
文摘First to third-generation calix[4] resorcinarene core dendrimers, compounds 4a, 4b, 7a, 7b, 10a and 10b, were prepared via the divergent method in seven steps with the corresponding tetraphenyl- and tetra (hydroxyphenyl) calix[4] resorcinarenes (compounds 1a, 1b) as the starting material. The repeat units of the polyamidoamines of these dendrimers were obtained by the ammonolysis of ethyl calixarylacetates 2a and 2b with 1,3-diaminopropane, that is, amide derivatives with terminal amino groups, which in turn reacted with ethyl acrylate to give a higher generation of ester derivatives. The structures of these dendrimers were characterized by IR, ^1H and ^13C NMR spoctrometries. The crystal structure of compound 2b with 12 ethoxycarbonylmethoxy groups was determined by X-ray analysis.