Regioisomer-Free C4h b-Tetrakis(tert-butyl)metallo- phthalocyanines: Regioselective Synthesis and Spectral Investigations

Metal b-tetrakis(tert-butyl)phthalocyanines are the most commonly used phthalocyanines due to their high solubility, stability, and accessibility. They are commonly used as a mixture of four regioisomers, which arise due to the tert-butyl substituent on the b-position, and to the best of our knowledge, their regioselective synthesis has yet to be reported. Herein, the C4hselective synthesis of b-tetrakis(tert-butyl)metallophthalocyanines is disclosed. Using tetramerization of a-trialkylsilyl phthalonitriles with metal salts following acid-mediated desilylation, the desired metallophthalocyanines were obtained in good yields. Upon investigation of regioisomer-free zinc b-tetrakis(tert-butyl)phthalocyanine using spectroscopy, the C4h single isomer described here was found to be distinct in the solid state to zinc b-tetrakis(tert-butyl)phthalocyanine obtained by a conventional method.