PREPARATION AND PHOTOPHYSICAL PROPERTIES OF AMIDE-LINKED, POLYPYRIDYLRUTHENIUM-DERIVATIZED POLYSTYRENE

The polymer (4{2-[N,N-bis(trimethylsilyl)amino]ethyl}styrene), prepare d by anionic polymerization and of low polydispersity (M-w/M-n = 1.10- 1.18), has been derivatized by amide linkage to [Ru-II(bpy)(2)(4-(CO-) -4'-CH3-bpy)-](2+) (bpy is 2,2'-bipyridine; 4-(CO-)-4'-CH3-bpy is 4-ca rbonyl-4'-methyl-2,2'-bipyridine). Unreacted amine sites were converte d into acetamides by treatment with acetic anhydride to give derivatiz ed polymers of general formula [PS-CH2CH2NHCO(Ru-n(II),Me-m)](PF6)(2n) , where m + n = 11, 18, or 25, PS represents the polystyrene backbone, and Ru-II and Me present the attached complex and acetamide, respecti vely. Spectral and electrochemical properties of the derivatized polym ers are similar to those of the model [Ru(bpy)(2)(4-CONHCH2CH2C6H5-4'- CH3-bpy)](2+) (4-CONHCH2CH2C6H5-4'-CH3-bpy is '-methyl-2,2'-bipyridiny l-4-(2-phenylethylamide)), but emission quantum yields (phi(em)) and t ime-resolved emission decays are slightly dependent on the level of Ru -II loading, with nonexponential, irradiation-dependent decays appeari ng at high loadings. The decays could be fitted satisfactorily to the first derivative of the Williams-Watts distribution function. These re sults are discussed with reference to possible structural and multichr omophoric effects on excited-state decay.