Synthesis of ionic boron amphiphilic diblock copolymers and pyridylborate ligands for transition metal complexes.

摘要

Atom transfer radical polymerization (ATRP) has been successfully used to prepare well-defined poly(trimethylsilyl)styrenes and the diblock copolymers, poly(trimethylsilyl)styrene-b-polystyrene, with controlled molecular weight and low polydispersity. Quantitative replacement of trimethylsilyl groups with boron tribromide in dichloromethane provided an important highly Lewis acidic intermediate that have allowed for the preparation of novel boron containing borate and boronium types of homopolymers and amphiphilic diblock copolymers with different post-polymerization modification processes. Characterizations including NMR spectroscopy, gel permeation chromatography (GPC) and the representative elemental analysis have been applied to confirm the quantitative transformations from the silylated polymers to the boron containing ionic polymers. The self-assembly properties in block selective solvents of the amphiphilic block copolymers were extensively studied. Most importantly, through an electro-static interaction, the weakly coordinating pentafluorophenyl borate block copolymers were successfully used to attach an organo-rhodium catalyst and then underwent self-assembly in selective solvent to give rise to transition metal containing micelles with well-defined nanostructures.;In the last chapter, synthesis and characterizations of a variety of novel multidentate pyridylborate ligands are described. An appropriate procedure for synthesis of 2-pyridyl magnesium chloride in a usual dimeric structure was developed. The 2-pyridyl magnesium chloride was then used to react with different arylbromoboranes in dichloromethane or toluene affording different multidentate ligands. The tris(2-pyridyl)borate ligands were the first pyridine based tripod ligands with a boron atom as the bridging head and their complexation with Fe(II) was studied by cyclic voltammetry (CV) and UV-vis spectroscopy. All the structures of the ligands and metal complexes were determined by single crystal X-ray spectroscopy. The styryltris(2-pyridyl)borate monomer was successfully polymerized in a free radical polymerization to give a polymer with good yield and high molecular weight. NMR analysis was used to confirm the formation of this novel polydentate polymer.