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The crown ether-linked iridium(III) complex [Ir(ppy)₂ (di-aza-phen)]⁺ (1) {ppy = 2-phenylpyridine and di-aza-phen = 4,7-di(1,4-dioxa-7,13-dithia-10-azacyclopenta-dec-10-yl)-1,10-phenanthroline (7)} has been prepared. Compound 1 exhibits a notable luminescence enhancement in the presence of Ag⁺ in aqueous media. The analogous ruthenium(II) complex [Ru(phen)₂(di-aza-phen)]²⁺ (4) {phen = 1,10-phenanthroline}, although equally exhibiting a luminescence enhancement in the presence of Ag⁺, is a far inferior sensor for Ag⁺ than 1. The 10 times higher luminescence enhancement (I − I₀)/I₀ of 1 was attributed to a dominance of the emission involving the di-aza-phen ligand that is responsible for binding to the metal ion. In contrast, the ³MLCT emission of 4 does not involve the di-aza-phen ligand but does involve the phen ligand, thus only allowing for a remote effect upon addition of Ag⁺ ions. While 1 is a …