Pyrazine- and Diazepine- Substituted Phthalocyanines: Synthesis and Optical Properties by Metal Ion Coordination

Abstract

The synthesis and characterization of new functionalized phthalocyanines with directly appended heterocyclic moieties (Pc1: pyrazines and Pc2: diazepines) are described. These phthalocyanine compounds (Pcs) contain four external metal binding sites, and each of them is formed by three nitrogen atoms. UV-vis spectral changes in the Pcs in CHCl₃ on adding metal ions indicated the occurrence of molecular aggregation, and UV titration studies showed 1:4 host-guest stoichiometry for complexation of Pcs especially with Cu²⁺ and Pb²⁺. Additionally, ESI-MS spectra and fluorescent X-ray spectroscopy also indicated the formation of a metal-phthalocyanine complex coordinated from the outside. The design strategy and optical properties of the Pcs help to extend the development of a phthalocyanine-based chemosensor for metal ions.