Tridentate cycloplatinated thiosemicarbazone complexes have been prepared from a biologically significant ligand, 3,4-dichloroacetophenone thiosemicarbazone (1). The tetranuclear complex 2 was prepared by reaction of the ligand with K2[PtCl4]. Two mononuclear (3 and 4) and two dinuclear (5 and 6) complexes were isolated upon cleavage of the Pt–Sbridging bonds of the tetranuclear complex 2 with the appropriate phosphane ligand. Each complex was characterized using various analytical and spectroscopic techniques, and the molecular structures of 2–4 were also elucidated. The in vitro antiparasitic activities of these complexes against Plasmodium falciparum strains (D10 (chloroquine sensitive) and Dd2 (chloroquine resistant)) and Trichomonas vaginalis have been determined. Preliminary studies into their potential plasmodial target in the form of β-hematin formation inhibition assays were also completed. Preliminary results suggest that ligand 1 and complex 3 do not hinder formation of β-hematin. The antiproliferative activity of the complexes against the cisplatin-senstive A2780 and cisplatin-resistant A2780cisR human ovarian cancer cell lines has been evaluated. The complexes were found to exhibit moderate to weak inhibitory activities.

New polynuclear organometallic Platinum Group Metal (PGM) complexes containing di- and tripyridyl ester ligands have been synthesised and characterised using analytical and spectroscopic techniques including (1)H, (13)C NMR and infrared spectroscopy. Reaction of these polypyridyl ester ligands with either [Ru(p-cymene)Cl2]2, [Rh(C5Me5)Cl2]2 or [Ir(C5Me5)Cl2]2 dimers yielded the corresponding di- or trinuclear organometallic complexes. The polyaromatic ester ligands act as monodentate donors to each metal centre and this coordination mode was confirmed upon elucidation of the molecular structures for two of the dinuclear complexes. The di- and trinuclear PGM complexes synthesized were evaluated for inhibitory effects on the human protozoal parasites Plasmodium falciparum strain NF54 (chloroquine sensitive), Trichomonas vaginalis strain G3 and the human ovarian cancer cell lines, A2780 (cisplatin-sensitive) and A2780cisR (cisplatin-resistant) cell lines. All of the complexes were observed to have moderate to high antiplasmodial activities and the compounds with the best activities were evaluated for their ability to inhibit formation of synthetic hemozoin in a cell free medium. The in vitro antitumor evaluation of these complexes revealed that the trinuclear pyridyl ester complexes demonstrated moderate activities against the two tumor cell lines and were also less toxic to model non-tumorous cells.

Two new di-and tripyridyl aromatic ether ligands (1 and 2) have been synthesized using the Williamson ether method. Functionalization of these ligands with either dichlorido(p-cymene)ruthenium(II), dichlorido(pentamethylcyclopentadienyl)rhodium-(III), or dichlorido(pentamethylcyclopentadienyl)iridium(III) fragments yielded three di-and three trinuclear organometallic complexes (1a−c and 2a−c). Both ligands act as monodentate donors to each metal center via the pyridyl nitrogen atoms, and this coordination mode of the polyaryl ether ligands has been confirmed upon elucidation of the molecular structure of the dinuclear iridium complex 1c. All of the synthesized compounds were evaluated for inhibitory effects on the Plasmodium falciparum strain NF54 (chloroquine-sensitive) and found to have moderate to high antiplasmodial activities, with the trinuclear complexes displaying activities in the nanomolar range. The most active compounds were studied for their ability to inhibit formation of synthetic hemozoin in a cell-free medium. Against the Trichomonas vaginalis strain G3, these aryl ether compounds were only moderately active.

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A series of mono- and bis-salicylaldimine ligands and their corresponding Rh(i) complexes were prepared. The compounds were characterised using standard spectroscopic techniques including NMR, IR spectroscopy and mass spectrometry. The salicylaldimine ligands and complexes were screened for antiparasitic activity against two strains of Plasmodium falciparum i.e. the NF54 CQ-sensitive and K1 CQ-resistant strain as well as against the G3 isolate of Trichomonas vaginalis. The monomeric salicylaldimine quinolines exhibited good activity against the NF54 strain and the dimeric salicylaldimine quinolines exhibited no cross resistance across the two strains. The binuclear 5-chloro Rh(i) complex displayed the best activity against the Trichomonas vaginalis parasite, possibly a consequence of its enhanced lipophilicity. The compounds were also screened for cytotoxicity in vitro against WHCO1 oesophageal cancer cells. The monomeric salicylaldimine quinolines exhibited high selectivity towards malaria parasites compared to cancer cells, while the dimeric compounds were less selective.