Synthesis of and Ferromagnetic Coupling in Poly(phenylenevinylene)s Bearing Built-in t-Butyl Nitroxides

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Abstract
Poly[[2- or 4-[N-t-butyl-N-(triethylsiloxy- or t-butyldimethylsiloxy)amino]-1,4- or 1,2-phenylene]vinylene] was synthesized by polymerizing 4- or 2-bromo-2- or 4-[N-t-butyl-N-(triethylsiloxy- or t-butyldimethylsiloxy)amino]styrene with a palladium catalyst, respectively. They were deprotected and chemically oxidized to yield poly(1,4- or 1,2-phenylenevinylene)s bearing a 2- or 4-substituted built-in nitroxide radical. The polyradicals were chemically stable, and their spin concentration was increased to 0.8 spin/unit. A SQUID measurement which included the corresponding diradicals and triradicals indicated that a partial, but strong, intramolecular ferromagnetic coupling was established through the conjugated backbone, despite a spin defect in the side radical moiety, for the poly(1,2- phenylenevinylene) bearing 4-substituted built-in nitroxide radical.