Highly Cross-linked Polymers Containing N,N′,N′′-Chelate Ligands for the Cu(II)-Mediated Hydrolysis of Phosphoesters Alexander Schiller, Rosario Scopelliti, Meriem Benmelouka, and Kay Severin* Institut des Sciences et Inge ´ nieries Chimiques, E Ä cole Polytechnique Fe ´ de ´ rale de Lausanne (EPFL), 1015 Lausanne, Switzerland Received March 28, 2005 Three immobilized Cu(II) complexes were generated by the following: (a) homopolymerization of the N,N′,N′′- chelate ligand tris[2-(1-vinylimidazolyl)]phosphine (1) and subsequent metalation with CuCl 2 ; (b) copolymerization of 1 with ethyleneglycol dimethacrylate (EGDMA) und subsequent metalation with CuCl 2 ; or (c) molecular imprinting with the organometallic Mo-complex [Mo(η 3 -C 4 H 7 )(CO) 2 (1)](TsO) (5) and EGDMA and subsequent replacement of Mo(II) by Cu(II). All three polymeric Cu complexes were found to efficiently promote the hydrolysis of activated phosphoesters with the relative activity being dependent on the nature of the polymer and the substrate. Introduction Copper(II) complexes of bi- and tridentate N-donor ligands such as bipyridine, 1 terpyridine, 2 and 1,4,7-triazacyclononane 3 and their derivatives have been investigated intensively as artificial phosphoesterases. 4 Being substitutionally labile and a strong Lewis acid, Cu 2+ is well-suited for such reactions. Compared to structurally related complexes of other M 2+ ions such as Zn 2+ , copper complexes often show a superior performance. 4 Nevertheless, most Cu-based synthetic phos- phoesterases described so far display some drawbacks. A general problem, which is shared by many other biomimetic hydrolases, was found to be product inhibition, resulting in low catalytic turnover. 4 Another setback frequently encoun- tered was the formation of catalytically inactive hydroxy- bridged dimers [L n Cu(µ-OH) 2 CuL n ] 2+ (L n ) multidentate N-donor ligand). 1c,e,2b,c,g,3a,c,d,f To circumvent this unfavorable dimer formation, sterically demanding groups were attached to the N-donor ligands. This strategy has been quite successful in producing complexes with an enhanced catalytic activity but an obvious drawback of such an approach is the reduced accessibility of the metal center. Furthermore, these groups may lead to a lower solubility of the catalyst in aqueous solution. The immobilization of Cu complexes on solid supports offers a potential alternative to reduce problems of aggregation and solubility and our efforts in this direction are reported below. 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Chem. 2005, 44, 6482-6492 6482 Inorganic Chemistry, Vol. 44, No. 18, 2005 10.1021/ic0504588 CCC: $30.25 © 2005 American Chemical Society Published on Web 08/12/2005