Synthesis and characterization of outer sphere-outer sphere connected organoplatinum dendritic networks from surface-difunctionalized and surface-trifunctionalized dendritic monomers

Two different approaches toward the syntheses of cross-linked dendritic networks from surface-functionalized polyether dendritic monomers were reported. The first series (type I) of dendritic networks (G1-G3) was prepared by a 3:2 copolymerization of surface bifunctionalized (G1-G3) dendritic monomers having two reactive arylethynyl surface groups with a small size trifunctional organoplatinum branching monomer {tris[trans-chlorobis(triethylphosphine) platinum]mesitylene-2,4,6-triethynylene} containing three reactive chloroplatinum functionalities. Facile network formation was realized for the G1 dendritic monomer, while linear, nonbranching dendritic polymers were predominately produced from the higher generation G2 and G3 monomers. The second series (type II) of dendritic networks (G0-G2) was prepared by a 3:2 copolymerization of a small size bifunctional organoplatinum monomer {bis [trans-chlorobis(triethylphosphine)platinum]-4,4′-biphenylene-1, 1′-diethynylene} having two reactive chloroplatinum moieties with surface-trifunctionalized (G0-G2) dendritic branching monomers with three reactive arylethynyl surface groups, Highly cross-linked dendritic networks were formed in all three generation of dendritic monomers. The structures of the soluble, linear dendritic polymers and the insoluble dendritic networks were characterized by nuclear magnetic resonance spectroscopy, gel permeation chromatography, scanning electron microscopy, scanning tunneling microscopy and/or energy-dispersive X-ray spectroscopy. The difference in the copolymerization behavior between these two approaches was rationalized in terms of steric inhibition during cross-linking in the type I dendritic network architecture.