The spectroscopy and dynamics of the low-lying triplet state of the proton-transfer tautomer in salicylaldehydes have been studied via internal heavy-atom effects coupled with a sensitive near-IR detecting system. For 3, 5-diiodosalicylaldehyde a weak proton-transfer keto-tautomer phosphorescence was resolved with a maximum at 710 nm (τ p∼ 1.8 μs, Φobs∼ 5.23× 10− 4) in a 77 K methylcyclohexane glass. The results, in combination with ...
