Iridium(III) bis-terpyridine complexes incorporating pendent N-methylpyridinium groups: luminescent sensors for chloride ions

Isomeric bis-terpyridine complexes of iridium(III) incorporating meta- or para-N-methylpyridyl substituents at the terpyridine 4'-position display long-lived luminescence in solution which is quenched by chloride ions to very different extents.