Poly(propylene imine) dendrimer complexes of Cu(II), Zn(II), and Co(III) as catalysts of hydrolysis ofp-nitrophenyl diphenyl phosphate

Vassilev, Krassimir; Ford, Warren T.

doi:10.1002/(sici)1099-0518(19990801)37:15<2727::aid-pola6>3.0.co;2-s

Cited by 48 publications

(10 citation statements)

References 65 publications

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“…At this point it is also worth stressing that some experimental techniques such as electron paramagnetic resonance (EPR), transmission electron microscopy (TEM), small- -angle neutron scattering (SANS), and small-angle X-ray scattering (SAXS) have already enabled an inspection of the above described phenomena. In particular, similar migration of ions to the molecule's interior has already been detected for poly(amidoamine) (PAMAM) dendrimers and metal ions (Cu, Pd, Au) [45][46][47][48][49]. Finally, the distributions of counterions in the vicinity of the end-beads and around each other are shown in Figs.…”

Section: Resultssupporting

confidence: 67%

The Structure of Dendrimers with Charged Terminal Groups: Monte Carlo Simulations

Majtyka

Kłos

2006

Acta Phys. Pol. A

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Taking into account the full Coulomb potential and the excluded volume interactions, properties of dendrimers with generations g = 5, 6 with charged terminal groups and counterions in an athermal solvent are examined by lattice Monte Carlo simulations. The study treats counterions explicitly and focuses on the local structure of the systems inspected by pair correlation functions g ab that provide information on distributions of monomers, terminal groups and ions in space at various temperatures T * . Special emphasis is placed on counterions and their role they play in causing conformational changes of the molecules. The simulations show that counterions penetrate the interior of the dendrimers, and there is a major increase in their concentration there as T * decreases. Some of them condense onto the terminal groups and a reduction in the mean effective charge Q of the dendrimers appears. Within the range of temperatures where the condensation (as a function of T * ) is sharp the molecules weakly swell up when compared to their size at the other temperatures. This kind of behaviour is also reflected by the distributions of monomers and terminal groups.

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Section: Resultssupporting

confidence: 67%

The Structure of Dendrimers with Charged Terminal Groups: Monte Carlo Simulations

Majtyka

Kłos

2006

Acta Phys. Pol. A

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“…Upon progressive addition of Cu 2+ the NP‐DAB suspensions become deep blue, which indicates that complexation readily takes place on the surface of the NPs. The visible spectra are similar to those obtained with DAB in aqueous solution, with a λ max around 635–675 nm for the d–d transition of the Cu(II)–dendrimer complexes 36–38. The spectrophotometric titration plots for dendrimer‐coated NPs (NP‐DAB4 and NP‐DAB16) and dendrimers DAB4 and DAB16 in aqueous solutions (Figure 4) are similar, which indicates that dendrimers attached to the NP surface exhibit a solutionlike behavior and retain their chelating capacity.…”

Section: Resultssupporting

confidence: 65%

“…The surfactant‐free suspensions of dendrimer‐grafted NPs are stable in the pH ranges of 3 to 6 and 2 to 7 for NL‐DAB4 and NL‐DAB16, respectively. The pK values of generation 1–3 dendrimers are 9.8 for the primary amines and 6.0 for the tertiary amines,35, 36 so that within these pH ranges the dendrimers could be assumed to be mainly in the protonated form, thus ensuring an electrostatic stabilization of the colloidal suspensions. Assuming complete protonation of the primary amines at pH 6–7,35 the surface charge densities, which are of the order of 0.8 and 1.5 meq g −1 for NP‐DAB4 and NP‐DAB16, respectively, are large enough to prevent aggregation regardless of the dendrimer generation.…”

Section: Resultsmentioning

confidence: 99%

“…DAB dendrimers have been shown to form well‐defined complexes with transition‐metal ions, such as Cu 2+ , Zn 2+ , Ni 2+ , and Co 2+ ,15, 36–38 and this capacity to trap metal ions has been used to produce embedded‐metal nanoclusters 38–40. We determined the metal‐binding capacity of the dendrimer‐functionalized NPs by spectrophotometric titration of the copper–dendrimer complexes.…”

Section: Resultsmentioning

confidence: 99%

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Convenient Synthesis and Properties of Polypropyleneimine Dendrimer‐Functionalized Polymer Nanoparticles

Larpent

Cannizzo

Delgado

et al. 2008

Small

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A simple synthesis of polymer core-dendrimer shell nanoparticles (NPs) in the 15-20-nm-diameter range is presented. Amine-terminated polypropyleneimine (PPI) dendrimers DAB-dendri-(NH(2))(4) and DAB-dendri-(NH(2))(16) (DAB4 and DAB16) are covalently attached to the surface of primary polystyrene-based NPs bearing reactive chlorobenzyl groups produced by microemulsion polymerization in the presence of a cationic surfactant. The grafting readily proceeds under mild conditions and leads to translucent aqueous suspensions of core-shell-type NPs with a high density of peripheral amine groups that have been characterized relative to their size and chemical composition. The dendritic shell acts as a protective ionizable outer layer and provides an improvement of the colloidal stability in neutral and acidic media. The metal-binding capacity of the PPI dendrimers is retained, and spectrophotometric titrations show that the dendrimer-grafted NPs can trap a large number of Cu(2+) ions (more than 900 Cu per NP-DAB16). These properties make them potentially valuable templates for the elaboration of hybrid nanomaterials. The reactivity of the external amine groups is used to link covalently azobenzene chromophores (disperse Red 1 residues) through aza-Michael addition in aqueous suspension. This simple method gives access to colored NPs with high dye contents in the outer layer (up to 1000-1500 dye molecules per NP), which indicates that dendrimer-functionalized NPs are valuable building blocks for the construction of multifunctional nanomaterials.

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“…[5,6] Three structures for a catalyst delivery system have been investigated, namely the core of the dendrimer as the single catalytic unit, [7] the dendritic box (intermediate positions within a dendrimer) [8] and the terminal ends of the dendrimer that covalently bind to catalytic units. [9][10][11][12][13] There are many examples of the use of functionalized dendrimers in catalysis of reactions including Heck couplings, [14][15][16] decarboxylation, [17] oxidation, [18] reduction, [19] Michael addition [20] and so on.…”

Section: Introductionmentioning

confidence: 99%

Chemo‐selective reduction of nitro and nitrile compounds using Ni nanoparticles immobilized on hyperbranched polymer‐functionalized magnetic nanoparticles

Rezaei

Malekzadeh

Poulaei

et al. 2017

Applied Organom Chemis

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The nitro and nitrile groups in aromatic and aliphatic compounds containing various reducible substituents such as carboxylic acid, ketone, aldehyde and halogen are selectively reduced to the corresponding amines in water as a green solvent with excellent yields by employing NaBH 4 in the presence of Fe 3 O 4 @PAMAM/Ni(0)-b-PEG nanocatalyst. The morphology and structural features of the catalyst were characterized using various microscopic and spectroscopic techniques. The designed catalyst system because of it being covered with hydrophilic polymers is soluble in a wide range of solvents (e.g. water and ethanol) and suitable for immobilizing and stabilizing Ni nanoparticles in aqueous mediums. In addition, the catalyst can be easily recovered from a reaction mixture by applying an external magnetic field and can be reused up to six runs without significant loss of activity.

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Poly(propylene imine) dendrimer complexes of Cu(II), Zn(II), and Co(III) as catalysts of hydrolysis ofp-nitrophenyl diphenyl phosphate

Cited by 48 publications

References 65 publications

The Structure of Dendrimers with Charged Terminal Groups: Monte Carlo Simulations

The Structure of Dendrimers with Charged Terminal Groups: Monte Carlo Simulations

Convenient Synthesis and Properties of Polypropyleneimine Dendrimer‐Functionalized Polymer Nanoparticles

Chemo‐selective reduction of nitro and nitrile compounds using Ni nanoparticles immobilized on hyperbranched polymer‐functionalized magnetic nanoparticles

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