Effects of metal ion in cationic Pd(II) and Ni(II) phthalocyanines on physicochemical and photodynamic inactivation properties

Four novel tetra non-peripheral 2-hydroxypyridine substituted palladium (II) and nickel (II) phthalocya-nines and their quaternized derivatives were synthesized. The phthalocyanines were fully characterized by different spectroscopic methods such as UV-Vis, FT-IR, 1 H NMR and MALDI-TOF mass spectrome-try. The quaternized phthalocyanines showed solubility in DMSO and water within a wide concentra-tion range and with lack of aggregation behavior. The singlet oxygen generation properties were deter-mined for quaternized phthalocyanine complexes in DMSO, water, and water + TritonX 100 solutions. The uptake capability and in vitro photodynamic activity studies performed on two pathogenic bacteria namely Gram (+) Methicillin-resistant Staphylococcus aureus (MRSA) and Gram (-) Aeromonas hydrophila suggested good potential of palladium (II) phthalocyanine complex (5) for the uptake and inactivation of planktonic cultured bacteria. Significant localization of water-soluble Pd(II) phthalocyanine complex was observed for MRSA biofilms. However, this resulted in low efficiency of pathogen inactivation. The newly synthesized nickel (II) phthalocyanine (6) showed lack of inactivation towards both bacterial strains under the applied mild treatment conditions. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Four novel tetra non-peripheral 2-hydroxypyridine substituted palladium (II) and nickel (II) phthalocyanines and their quaternized derivatives were synthesized and fully characterized. The quaternized phthalocyanines showed good solubility and singlet oxygen generation properties. The palladium (II) phthalocyanine complex demonstrated good uptake and inactivation capabilities towards Gram (+) Methicillin-resistant Staphylococcus aureus (MRSA) while the newly synthesized nickel (II) phthalocyanine lacked inactivation towards both bacterial strains.