Synthesis, optical and electrochemical properties of novel phenyl- and phenoxy-substituted subphthalocyanines

• Novel phenyl- and phenoxy-substituted subphthalocyanines were synthesized.
• The influence of a heavy atom effect on intersystem crossing was demonstrated.
• Picosecond lifetimes of high-lying excited states were established.
• Higher electron-donating ability of phenyl- compared to phenoxy groups was shown.

Novel phenyl- and phenoxy-substituted subphthalocyanines bearing a halogen ion in the axial position were synthesised. The compounds obtained were characterised by 1H, 13C and 1H–1H nuclear Overhauser effect spectroscopy and high resolution mass spectrometry. The correlation between the position of the Q-band and the nature of axial or peripheral substituents was shown. Redox transitions of the compounds were characterised using cyclic voltammetry in o-dichlorobenzene. The redox potentials determined suggest a higher electron-donating ability of phenyl substituents compared to phenoxy groups. Absorption cross sections, quantum yields of fluorescence and intersystem crossing, lifetimes of excited states and non-linear optical properties were studied using UV–Vis spectroscopy, stationary and time-resolved fluorimetry, and a non-linear Z-scan technique.

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