Self-assembly of a symmetrical dimethoxyphenyl substituted Zn(II) phthalocyanine into nanoparticles with enhanced NIR absorbance for singlet oxygen generation

Phthalocyanine (Pc) molecules have been investigated as photosensitizers (PS) for singlet oxygen (1O2) generation because of their intense absorption bands in the near-infrared region, which is desirable for applications such as photodynamic therapy (PDT). Here, we have designed a sterically crowded symmetrical Zn(II) phthalocyanine (PC-1), which contains 8 dimethoxyphenyl substituents, and studied its optical properties. PC-1 exhibits good thermal stability, appropriate theoretical HOMO and LUMO energy levels and band gap which are suitable for optoelectronic applications. PC-1 was converted into hydrophilic nanoparticles (PC-1NPs) via a solvent exchange based self-assembly approach, which exhibited good water dispersability, as well as uniform morphology and size. Optical studies revealed a bathochromic-shift in absorbance in the NIR wavelength region and 1O2 generation. These results suggest that PC-1 phthalocyanine is a potential candidate for photoinduced oxidative processes in biological and catalytic applications.