Development of ruthenium polypyridine metallo-monomers and characterization of their metallopolymers obtained by ROMP

Abstract

Two novel metallo-monomers, [Ru(polypyridine)₂NEN](PF₆)₂, polypyridine = 1,10-phenanthroline (phen) (3) or 2,2′-bipyridine (bpy) (5), were obtained from the reaction of cis-[RuCl₂(polypyridine)₂] with the novel N,N′-bis(norbornene)ethylenediamine (NEN) monomer ligand. These metallo-monomers were investigated using spectroscopic and electrochemical techniques and showed behavior typical of polypyridine Ru(II) complexes, such as electronic transitions in the visible region with molar absorptivity of the order of 10⁴ M⁻¹ cm⁻¹ and relevant emission intensity in the 600 nm region. Complexes 3 and 5 were then copolymerized with norbornene (NBE) via ring opening metathesis polymerization (ROMP) to generate metallopolymers of type [Ru((polypyridine)NEN)_n-(NBE)_m]²⁺. ¹H NMR monitoring of the ROMP reaction, as well as spectroscopic measurements of the isolated materials in the solid state, showed that the target properties of the metallo-monomers, such as non-porous surface and luminescence, are present in the generated metallopolymers.