BSA/DNA binding behavior and the photophysicochemical properties of novel water soluble zinc(II)phthalocyanines directly substituted with piperazine groups

In the current research, two novel zinc(II) phthalocyanines (ZnPcs) ( 1 and 2 ) directly connecting with 4-(4-methylpiperazin-1-yl)phenyl groups have been synthesized through the Suzuki–Miyaura coupling reaction. These ZnPcs 1 and 2 were converted to their water-soluble derivatives ( 1Q and 2Q ) by quaternization. The photochemical and photophysical properties were determined in DMSO for the non-ionic zinc(II) phthalocyanines ( 1 and 2 ) and in both DMSO and aqueous solutions for the quaternized cationic derivatives ( 1Q and 2Q ) to establish their photosensitizer capabilities in photodynamic therapy (PDT). The spectrofluorometric and spectrophotometric techniques were employed for the determination of interaction between water-soluble ZnPcs ( 1Q and 2Q ) and BSA or ct-DNA. The binding constants of these compounds to BSA were found in the order of 10 8 M −1 . The binding constant of the ct-DNA interaction with 2Q (1.09 × 10 5 M −1 ) was found higher than 1Q (6.87 × 10 4 M −1 ). The thermodynamic constants were determined for both 1Q and 2Q . The endothermic and spontaneous nature of interaction was observed with ct-DNA. Besides, the thermal denaturation and viscosity studies proved the non-intercalative mode of binding for both compounds to ct-DNA. Graphic abstract