Synthesis and photophysical properties of a novel zinc photosensitizer and its gold nanoparticle conjugate

The peripherally tetra substituted zinc phthalocyanine with 1,6-hexanedithiol as substituent (THdTZnPc, 3) was synthesized and is reported for the first time in this work. The potential of this zinc complex as a suitable photosensitizer for use in photodynamic therapy was determined through the investigation of the photophysical and photochemical properties. In this work complex 3 is attached to gold nanoparticles through the terminal thiol groups of the phthalocyanine resulting in a 3-AuNP conjugate whose photophysicochemical properties are investigated. Fluorescence lifetimes were determined using time correlated single photon counting and they show an increase in the abundance of the monomeric species (τ2) for the Pc in the 3-AuNP conjugate: ∼1 and 0.71 (with respective lifetimes 2.69 ns and 2.86 ns) compared to the free complex 3 with abundances of 0.12 and 0.13 (with respective lifetimes 3.36 ns and 3.28 ns) in DMSO and DMF, respectively.

Zinc phthalocyanine peripherally tetra substituted with 1,6-hexanedithiol shows improved photophysical behaviour when attached to gold nanoparticles.Figure optionsDownload as PowerPoint slideHighlights
► Zinc phthalocyanine substituted with hexanedithiol was synthesized.
► The complex was attached to gold nanoparticles.
► Fluorescence lifetimes were determined.
► Lifetimes show an increase in the abundance of the monomeric species.