Synthesis and characterization of potential organic magnetic materials, light-emitting diodes, and biosensors
Abstract (Summary)Three kinds of potential new materials: organic magnetic materials, light emitting diodes (LED), and biosensors have been designed and synthesized. Phenoxy based radicals are the research focus of the magnetic materials part of this dissertation. Three types of ferromagnetic linkages, pendant conjugated polymer backbone, hydrogen bonding, and metal coordination, were used to exchange couple the hindered 2,6-di-t -butyl-phenoxy radical system. Both regioregular and regiorandom polythiophene-based phenoxyl polyradicals have been synthesized. The regioregular polyradical exhibits a strong, persistent electron spin resonance spectrum and a UVvisible spectrum consistent with formation of the pendant phenoxyl spin-bearing units. A benzimidazole based phenoxyl radical with hydrogen bonding ability was obtained as a deep blue solid which survived in air for more than one year. This is one of the most stable phenoxyl radicals ever reported. Phenoxyl radicals with coordination ligands (pyridine, pyrimidine, carboxylate) have been synthesized by Suzuki reaction. No metal coordinated phenoxyl was obtained, though one copper coordinated precursor phenol with interesting IR properties was prepared successfully. Four poly(3-arylthiophene) based conjugated polymers have been synthesized: poly[(3,5-di-t -butyl-4-methoxyphenyl)thiophenevinylene-co- p -phenylenevinylene], poly[(3,5-di-t -butyl-4-methoxyphenyl)thiophenevinylene-co- m -phenylenevinylene], poly[(3,5-di-t -butyl-4-methoxyphenyl)thiopheneethnylene-co- m -phenyleneethnylene], and poly[4-(3,5-di-t -butyl-4-methoxyphenyl)thiophene-2-vinylene]. They are all soluble in common organic solvents and have strong fluorescence both in solution or film form. They emit light from yellow-green, yellow, red, to dark red under UV light. They are potential LED materials. A polythiophene based biosensor have been prepared in a six-step synthesis. This water-soluble conjugated polymer, sodium poly[2-(4-methyl-3-thienoxy)ethanesulfonate-co-4-methyl-3-(6-hydroxylhexyloxy)]thiophene, has been biotinylated on its side chain. The purple red neutral aqueous solution of this polymer turns green in an acidic solution.
School Location:USA - Massachusetts
Source Type:Master's Thesis
Date of Publication:01/01/2000