The synthesis and characterization of novel platinum(II) complexes containing salicylaldimine ligands derived from lipophilic amines

Abstract

Cisplatin has been used for treating cancers since its FDA approval in 1978. It’s ability to lose the chlorine atoms and form adducts within the DNA of tumor cells causing cell death makes it a useful agent in treating cancers. However, its shortfalls including low-solubility, acquired resistance to the drug, as well as its side effects and toxicity have left researchers searching for a better alternative. Recent work focused on developing a new design strategy for cisplatin analogues has utilized salicylaldehyde to form salicylaldimine, which can be coordinated to platinum in a bidentate fashion. Using this strategy, this study created three novel platinum complexes containing lipophilic amines. All Schiff bases synthesized were created from salicylaldehyde and an aniline derivative containing a long carbon chain. These were then complexed to the metal to give novel organometallic platinum(II) complexes containing a cyclooctene group. 1H NMR, 13C{1H} NMR spectroscopy were used to confirm the imine formation as well as the coordination of the free ligands to platinum. A shift in the FTIR spectra were observed when the imine coordinated to the metal centre. The melting points of both the Schiff bases and the platinum compounds were found to decrease with the increasing carbon chain length.