Synthesis and antimicrobial photodynamic activities of axially {4-[(1E)-3-oxo-3-(2-thienyl)prop-1-en-1-yl]phenoxy} groups substituted silicon phthalocyanine, subphthalocyanine on Gram-positive and Gram-negative bacteria

Today, the problem of antimicrobial resistance is the most important cause of morbidity and mortality in the treatment of infectious diseases worldwide. Therefore, alternative treatment strategies are important for controlling infectious diseases. In the basic principle of antimicrobial photodynamic therapy (aPDT), when harmless light at the appropriate wavelength absorbed by the photosensitizer, undergoes a transition from a ground state to a triplet state. The triplet state photosensitizer can interact with enzym and substrate molecules to produce free radicals and radical ions, or with molecular oxygen resulting in the generation of singlet oxygen which leads to cell cytotoxicity of the microorganism. For this purpose, axially {4-[(1E)-3-oxo-3-(2-thienyl) prop-1-en-1-yl] phenoxy} group substituted silicon phthalocyanine (Es-SiPc) and subphthalocyanine (Es-SubPc) were synthesized by reaction of SiPcCl2, SubPcCl with (2E)-3-(4-hydroxyphenyl)-1-(2-thienyl)prop-2-en-1-one in the presence of NaH in toluene. The new Es-SiPc and Es-SubPc were characterized by standard spectroscopy methods. The effects of aPDT in the presence of phthalocyanines were investigated against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) strains. Also, singlet oxygen generation of Es-SiPc and Es-SubPc were investigated. Our results suggest that the aPDT in the presence of newly synthesized Es-SiPc and Es-SubPc has promising antibacterial effects on Gram-positive and Gram-negative bacteria.