Luminescent Zn and Pd Tetranaphthaloporphyrins

Zn and Pd complexes of meso-tetraphenyltetranaphthaloporphyrins (Ph4TNP) exhibit strong infrared absorption bands and luminesce in solutions at room temperature. S1 → S0 fluorescence (λmax = 732 nm, φ = 5.3%) is the predominant emission in the case of ZnPh4TNP (1). This emission is in part due to the delayed fluorescence (φ = 1.1%). Phosphorescence (T1 → S0) of 1 (λmax = 973 nm) is very weak (φ = 0.04%) and occurs with lifetime of about 440 μs in deoxygenated DMF. In the case of PdPh4TNP (2), almost no S1 → S0 fluorescence could be observed, while the main emission detected was T1 → S0 phosphorescence (λmax = 938 nm). The phosphorescence of 2 occurs with lifetime of about 65 μs and (φ=6.5%) in deoxygenated DMF solution. Metalloporphyrins 1 and 2 are promising near infrared dyes biomedical applications.