Pyrazolylcyclotriphosphazene Containing Pendant Polymers:  Synthesis, Characterization, and Phosphate Ester Hydrolysis Using a Cu(II)-Metalated Cross-Linked Polymeric Catalyst

Abstract

A multi-pyrazolyl cyclotriphosphazene containing polymerizable group N(3)P(3)(3,5-Me(2)Pz)(5)(O-C(6)H(4)-p-C(6)H(4)-p-CH=CH(2)) (2) has been prepared from the corresponding chloro derivative N(3)P(3)Cl(5)(O-C(6)H(4)-p-C(6)H(4)-p-CH=CH(2)) (1). The X-ray structures of 1 and 2 have been determined. Compound 2 undergoes ready metalation with CuCl(2) to afford N(3)P(3)(3,5-Me(2)Pz)(5)(O-C(6)H(4)-p-C(6)H(4)-p-CH=CH(2)).CuCl(2) (3). Model compound N(3)P(3)(3,5-Me(2)Pz)(5)(O-C(6)H(4)-p-CHO).CuCl(2) (6) has been prepared and characterized by spectroscopy and X-ray crystallography. In this compound, the coordination around copper is distorted trigonal bipyramidal, and the cyclotriphosphazene coordinates in a non-gem N(3) mode. Compound 2 has been copolymerized with divinylbenzene to afford cross-linked multisite coordinating polymer CPPL which is readily metalated with CuCl(2) to afford copper-containing polymer CPPL-Cu. The coordination environment around copper in CPPL-Cu has been evaluated by obtaining its EPR, optical, and IR spectra and comparing them with those of model compounds 3 and 6. The utility of CPPL-Cu as a heterogeneous catalyst has been demonstrated in the phosphate ester hydrolysis involving three model phosphate esters: p-nitrophenyl phosphate (pNPP), bis(p-nitrophenyl) phosphate (bNPP), and 2-(hydroxypropyl)-p-nitrophenyl phosphate (hNPP). In all of these reactions, a significant rate enhancement of ester hydrolysis is observed. Detailed kinetic analyses to evaluate Michaelis-Menten parameters have also been carried out along with experiments to elucidate the effect of pH, solvent, and temperature on the rate of hydrolysis. Recycling experiments on the hydrolysis of pNPP with CPPL-Cu shows that it can be recycled several times over without affecting the rates.

Tailored Control and Optimisation of the Number of Phosphonic Acid Termini on Phosphorus‐Containing Dendrimers for the Ex‐Vivo Activation of Human Monocytes

“…Spectroscopic data are in accordance with that described by Chandrasekhar et al [37] Figure 6. Screening of the bioactivity of various dendrimers towards human monocytes (mfi-R for HLA-DR and CD14 markers).…”

Transition Metal‐Assisted Hydrolysis of Pyrazole‐Appended Organooxotin Carboxylates Accompanied by Ligand Transfer

“…[3][4][5] We and others have been pursuing the possibility of using inorganic cores for building star-burst-type molecules. [6][7][8][9][10][11][12][13][14] Thus, inorganic rings such as cyclophosphazenes, [6,8] cyclosiloxanes, [9] and borazines [10] have been used recently as supports for the preparation of novel compounds which contain a central inorganic core and a periphery of judiciously placed functional substituents. Other inorganic rings and cages that contain Al-N or Al-C units have been similarly investigated.…”

A Copper‐Metalated, Hybrid Inorganic–Organic Polymer as an Oxidative Nuclease

“…From the nitrogen analysis it is concluded that every gram of the polymer contains 0.33 g of the cyclophosphazene monomer corresponding to 4.09 × 10 -4 moles. From the AAS analysis the amount of copper present per gram of CPPL-Cu was found to be 21.7 mg. [21] Plasmid (pBR322) modification assisted by the CPPLCu complex was studied in the presence of exogenously added co-oxidants MMPP and oxone. Initial experiments were performed using a varying amount of polymer in the www.eurjic.org presence of MMPP to study the concentration-dependent cleavage of pBR322.…”