A novel alternative route to access rhenium(V)-phthalocyanine complexes through direct metalation of metal-free phthalocyanines (H2 Pcs) with a rhenium(VII) salt in the presence of various two-electron reducing agents is presented. Direct ion metalation of tetraamino- or tetranitrophthalocyanine with perrhenate (ReO4- ) in the presence of triphenylphosphine led to oxidative decomposition of the H2 Pcs, giving their respective phthalonitriles. Conversely, treatment of H2 Pcs with ReO4- employing sodium metabisulfite yielded the desired ReV O-Pc complex. Finally, reaction of H2 Pcs with ReO4- and NaBH4 as reducing agent led to the formation of rhenium oxide (Rex Oy ) nanoparticles (NPs). The NP synthesis was optimised, and the Rex Oy NPs were capped with folic acid (FA) conjugated with tetraaminophthalocyanine (TAPc) to enhance their cancer cell targeting ability. The cytotoxicity profile of the resultant Rex Oy -TAPc-FA NPs was assessed and found to be greater than 80 % viability in four cell lines, namely, MDA-MB-231, HCC7, HCC1806 and HEK293T. Non-cytotoxic concentrations were determined and employed in cancer cell localization studies. The particle size effect on localization of NPs was also investigated using confocal fluorescence and transmission electron microscopy. The smaller NPs (≈10 nm) were found to exhibit stronger fluorescence properties than the ≈50 nm NPs and exhibited better cell localization ability than the ≈50 nm NPs.
Keywords: hydrolytic cleavage; metalation; phthalocyanines; rhenium; rhenium oxide nanoparticles.
© 2022 The Authors. Published by Wiley-VCH GmbH.