Water soluble near infrared dyes based on PEGylated-Tetrapyrrolic macrocycles

The design and synthesis of new near infrared (NIR) biocompatible dyes have been of great interest over the last years. Herein, the synthesis of two new water soluble NIR dyes is reported: a PEGylated (PEG = polyethyleneglycol) fluorinated bacteriochlorin [5,10,15,20-tetrakis(4-PEG(500)-2,3,5,6-fluorophenyl)bacterio-chlorin], prepared in a straightforward synthetic strategy involving a solventless reduction; and an improved strategy to prepare a PEGylated tetra-substituted free-base phthalocyanine [2(3),9(10),16(17),23(24)-tetrakis(4-PEG(200))phthalocyanine], obtained in 52% overall yield, from the PEGylated phthalonitrile. Photophysical characterization and photostability studies were performed, where both dyes showed favorable photostability and the PEGylated fluorinated bacteriochlorin presented good singlet oxygen quantum yield, showing potential to use as a photosensitizer for PDT (photodynamic therapy). Additionally, the free-base PEGylated phthalocyanine displayed reasonably high Stokes shift, suggesting high potential to use in optical imaging.

Automated summary

The design and synthesis of new near infrared (NIR) biocompatible dyes have garnered significant interest in recent years. This study reports the synthesis of two new water soluble NIR dyes with favorable photostability and potential for applications in photodynamic therapy and optical imaging.