Synthesis, characterisation and cytotoxicity studies of Manganese(I) and Rhenium(I) based metallacrown ethers

• Self-assembly of two components resulted into the formation of ML type metallacrown ether.
• Neutral Mn(I) and Re(I) based mononuclear metallacrown ethers were synthesised in one-pot reaction.
• Flexible polyether spacer and fac-M(CO)3 (MMn, Re) units were utilised for metallacrown ether synthesis.
• Molecular structure of metallacrown ether was ascertained by single-crystal X-ray crystallography.
• Cytotoxicity studies of Mn(I) and Re(I) compounds on cancer cells confirmed the selective inhibition of certain cancer cells.

Manganese(I) and Rhenium(I) based metallacrown ethers [M(CO)3Br(μ-pcatgd)] (1, M = Mn; 2, M = Re) were synthesised by the reaction of M(CO)5Br (M = Mn, Re) and pyridine appended bidentate ligand crafted with flexible polyether spacer. The self-assembled mononuclear compounds 1 and 2 were characterised by IR, NMR, UV–Visible absorption and emission spectroscopic techniques. Molecular structure of 2 was determined by single-crystal X-ray diffraction methods and the molecular masses of 1 and 2 were confirmed by ESI–mass spectrometry. Anticancer activities of compounds 1 and 2 were investigated by in vitro cytotoxicity studies against different cancer cell lines as well as on normal cells. Compounds 1 and 2 showed a broad-spectrum inhibition on few cancer cells that were comparable to cisplatin. Compound 1 exhibited selective inhibition of cancer cells upon irradiation at λmax 365 nm in dose-dependent manner. Morphological studies showed the induction of apoptosis in compound 1-treated cancer cells upon irradiation. The UV–Visible absorption spectroscopy-based myoglobin assay further supported the nature of compound 1 as photoactivatable CO releasing molecule (PhotoCORM).

Manganese(I) and Rhenium(I) based metallacrown ethers [M(CO)3Br(μ-pcatgd)] (1, MMn; 2, MRe) were synthesised by the reaction of M(CO)5Br and pyridine appended polyether spacer. Compounds 1 and 2 showed a broad-spectrum inhibitory activity on few cancer cells comparable to a reference compound (cisplatin).Figure optionsDownload as PowerPoint slide