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

Abstract

Poly(propylene imine) dendrimers having 8, 32, and 64 primary amine end groups form diamino Cu(II), diamino Zn(II), and tetramino Co(III) complexes that are identified spectrophotometrically and titrimetrically. The dendrimer-metal ion complexes catalyze the hydrolysis of p-nitrophenyl diphenyl phosphate in zwitterionic buffer solutions at pH Յ 8.1 with relative activities Cu(II) Ͼ Zn(II) Ͼ Co(III). The rates of hydrolysis are faster with sodium perchlorate than with sodium chloride to control ionic strength. In sodium perchlorate solutions with Cu(II) the rates increase with increasing size of the dendrimer. In sodium chloride solutions with Cu(II) the rates decrease with increasing size of the dendrimer. Rate constants in buffered sodium chloride solutions of dendrimers and 1.0mM Cu(II) are 1.3-6.3 times faster than in the absence of Cu(II). The fastest hydrolyses occurred at a dendrimer primary amine to Cu(II) ratio NH 2 /Cu Յ 2. At NH 2 /Cu ϭ 4 and with the 1,4,7,10-tetraazacyclodecane complex of Cu(II) hydrolysis rates were much slower.

Dendrimer-Encapsulated Metals and Semiconductors: Synthesis, Characterization, and Applications

“…A partial list of metal ions that have been bound to these dendrimers in this way includes Na + , K + , Cs + , Rb + , Fe 2+ , Fe 3+ , Gd 3+ , Cu + , Cu 2+ ,Ag + , Mn 2+ , Pd 2+ , Zn 2+ , Co 3+ , Rh + , Ru 2+ , and Pt 2+ [18,19,27,36,54,[82][83][84][85][86][87][88][89][90][91][92][93][94][95][96]. Turro et al have also shown that the metal ion complexes, such as tris(2,2¢-bipyridine)ruthenium (Ru(bpy) 3 ), can be attached to PAMAM dendrimer surfaces by electrostatic attraction [97].…”

“…Molecular catalysts, often in the form of metal ions complexed to a suitable ligand, can also be attached to dendrimer surfaces [3,9,10,93,94,96,148,149]. Such materials are generally structurally better defined than catalysts bounded to linear polymers, but like random-polymer catalysts they can be easily separated from reaction products.…”

Organic/inorganic hybrid nanospheres based on hyperbranched poly(ethylene imine) encapsulated into silica for the sorption of toxic metal ions and polycyclic aromatic hydrocarbons from water

“…It is well known that amine-terminated dendrimers, as for example the commercially available poly(amidoamine) and poly(propylene imine) dendrimers, can encapsulate organic molecules [1] as well as metal ions dissolved in water [2][3][4][5][6][7][8] and can therefore be employed in water purification devices. Their properties depend on the structural characteristics of the branches in their interior, and on the large number of surface end-groups that are susceptible to functionalization or even multi-functionalization, affording polymers with diversified, tailor-made, properties so as, for instance, to render these polymers insoluble in water by attaching hydrophobic groups [9] or by performing cross-linking reactions [10].…”

Preparation, structure and properties of metal–copolymer complexes of poly-4-vinylpyridine radiation-grafted onto polymer films

“…The main comments in these publications were associated with the possible use of metal-containing monomers as precursors for the preparation of catalysts and catalyst supports. Poly(propylene imine) dendrimers, which are able to form complexes with Cu(II), Zn(II), Co(III) and catalyze hydrolysis of bis-(pnitrophenyl) phosphate [6] and p-nitrophenyl diphenyl phosphate [7] have also been reported.…”