© 2021In the present study, peripherally tetra-substituted metal-free (H2Pc), Mg(II) (MgPc) and In(III)CI (InPc) phthalocyanine compounds containing carboxylic acid moieties were synthesized and characterized by various spectroscopic techniques. Photophysical, photochemical and aggregation properties of these compounds, which are show good solubility in DMSO, DMF and THF, were investigated. Aggregation behaviors of these phthalocyanines were investigated using DMSO and DMF in different concentrations. The photophysicochemical properties including fluorescence spectra and quantum yield, singlet oxygen generation and photodegradation behavior were researched in DMSO and DMF to clarify the usability of these compounds as a photosensitizers. In addition, the effects of the presence and absence of metal ion on photochemical and photophysical properties of these phthalocyanines are also examined. The metallo phthalocyanines (Mg(II) and In(III)CI) showed high singlet oxygen generation efficiency compared to metal-free phthalocyanine derivative. According to singlet oxygen generation efficiency, we can say that the presence of metal ion on phthalocyanine ring increases singlet oxygen generation. The results show that these compounds may have potential to be used as a photosensitizers in photodynamic therapy (PDT) applications.