Electrogenerated chemiluminescence in an electrodeposited redox hydrogel

We report the electrodeposition, under physiological conditions, of an electrochemiluminescent (ECL) Ru2+/3+ complex-containing redox hydrogel. The ECL-hydrogels were formed by potential cycling of a solution of [poly(4-vinylpyridine)Ru(2,2′-bipyridine)2Cl−]+/2+, its un-coordinated backbone pyridines partially quaternized with bromoethylamine for solubility in water and for swelling to a hydrogel after crosslinking. The polymer was electrosorbed on plasma-oxidized graphite in the anodic half of the cycle and irreversibly crosslinked, to form a swelling but insoluble film, in the cathodic half cycle. The ECL resulted of the chemical reaction of electro-oxidatively produced tri-n-propylamine-radical with the hydrogel’s Ru2+ centers. The emission spectra of the photo-excited films and their ECL spectra were identical. The ECL-emission increased one thousand-fold, linearly with the tri-n-propylamine (TPrA) concentration, between 100 nM and 0.1 mM.