LAUSR

Cationic Zn phthalocyanine complexes derived by alkylation reaction of tetra-(pyridinyloxy) phthalocyanines at the ortho, meta, and para positions to form Zn (II) Tetrakis 3-(4-(2-pyridin-1-ium-1-yl) butyl)-2-mercapto-4,5-dihydrothiazol-3-ium phthalocyanine (2), Zn (II) Tetrakis 3-(4-(3-pyridin-1-ium-1-yl) butyl)-2-mercapto-4,5-dihydrothiazol-3-ium phthalocyanine (4) and Zn (II) Tetrakis 3-(4-(4-pyridin-1-ium-1-yl) butyl)-2-mercapto-4,5-dihydrothiazol-3-ium phthalocyanine (6). The photophysicochemical behaviours of the Pc complexes are assessed. The meta and para-substituted complexes demonstrate high singlet oxygen quantum yields. The cationic Pcs demonstrate good planktonic antibacterial activity towards Staphylococcus aureus and Escherichia coli with the highest log reduction values of 9.29 and 8.55, respectively. The cationic complexes also demonstrate a significant decrease in the viability of in vitro biofilms after photo-antimicrobial chemotherapy at 100 µM for both Staphylococcus aureus and Escherichia coli biofilms.