Three novel phthalocyanine derivatives equipped with bulky substituents at non-peripheral positions were synthesized and their physico-chemical properties were analyzed. Singlet oxygen generation as well as the aggregation properties of the phthalocyanines with different sizes of peripheral substituents were thoroughly studied. An insertion of benzyloxy or 3,5-bis(benzyloxy)benzyloxy groups to the non-peripheral positions of phthalocyanines increased the singlet oxygen generation efficacy compared with a phthalocyanine substituted with 2-propoxy groups.