Consequences of isosteric replacement of benzene for pyrazine in phthalocyanines

Abstract

Tetrapyrazinoporphyrazines (TPyzPzs) likely represent the most investigated group of azaanalogs of phthalocyanines. This review highlights the author’s contributions in this field and summarizes the most important features of these interesting macrocycles with the aim of emphasizing the differences from the parent phthalocyanines. In particular, uniqueness in synthesis, spectral, photophysical and electrochemical properties are discussed. Thanks to systematic investigation of intramolecular charge transfer with TPyzPzs as electron acceptors, detailed structure-activity relationships of this ultrafast quenching process have been disclosed. This opened the door for the use of TPyzPzs as fluorescence sensors and quenchers in oligodeoxynucleotide probes, the latter being unique for TPyzPzs, which have not been investigated with phthalocyanines. These two applications seem to be much more suitable for TPyzPzs than photodynamic therapy, where the phthalocyanines typically have superior in vitro activities.