Assessment of the relevance of GaPc substituted with azido-polyethylene glycol chains for photodynamic therapy. Design, synthetic strategy, fluorescence, singlet oxygen generation, and pH-dependent spectroscopic behaviourElectronic supplementary information (ESI) available. See DOI: 10.1039/c7nj01390f

A new efficient synthetic route was used to obtain symmetrically and asymmetrically substituted gallium( iii ) phthalocyanines ( 5-GaCl and 6-GaCl ) containing azido groups with chlorine atoms at axial positions, using corresponding ZnPc derivatives ( 5-Zn and 6-Zn ) as precursors. The photophysical and photochemical properties-fluorescence, singlet oxygen generation, and photodegradation-of 5-GaCl and 6-GaCl were compared with that of 5-Zn and 6-Zn . Their pH-sensitive spectral changes were also investigated in detail, as tumours are more acidic than healthy tissues. Their amphiphilicity, quantified by their partition coefficient, appeared suitable for biological applications. 5-GaCl and 6-GaCl exhibited higher photodynamic potential than unsubstituted gallium( iii ) phthalocyanine, suggesting potential to be used as a photodynamic therapy agent. New synthetic route and PDT potential of symmetrically and asymmetrically substituted Ga( iii )Pcs with terminal azides.