Synthesis and characterization of amide-derivatized, polypyridyl-based metallopolymers

A new series of soluble metallopolymers based on amide-derivatized, styrene-p-(aminomethyl) styrene, containing on the average 16 repeat units, has been synthesized. The amino copolymer was prepared by treating styrene-p-(chloromethyl)styrene with potassium phthalimide and then with hydrazine monohydrate. The derivatization chemistry is based on amide coupling to the amino polymer. The aminated polymer was derivatized by reaction with a stoichiometric amount of the acid-functionalized metal complexes, [M(II)b(2)b-COOH](PF6)(2)] (M(II) = Ru-II, Os-II; b = 2,2'-bipyridine, b-COOH = 4'-methyl-2,2'-bipyridine-4-carboxylic acid), in the presence of a coupling reagent. The remaining amino sites were capped by the acetyl group by treatment with acetic anhydride. Samples of varying composition, [co-PS-CH2NHCO-(Ru(x)(II)Me(16-x))](PF6)(2x) (x = 4, 7, 9, 12, 16) and [co-PS-CH2NHCO(Os(x)(II)Me(16-x))](PF6)(2x) (X = 4, 8, 16) have been prepared where M(II) is an abbreviation for [M(II)b(2)b-CONH-](2+) (M = Ru, Os) and Me for the methyl of the acetamide group. Compositions were determined by H-1-NMR and infrared spectroscopy. Photophysical properties of the samples have been studied as a function of loading and of solvent. All exhibit characteristic metal-to-ligand charge transfer absorptions and emissions which are only slightly solvent dependent. In some cases, luminescence decays are nonexponential but could be fit to a sum of two exponentials. Quantum yields and kinetic decay parameters are dependent on solvent, extent of loading, and incident excitation intensity.