Joshua A. Obaleye

Synthesis and biological activities on metal complexes of 2,5-diamino-1,3,4-thiadiazole derived from semicarbazide hydrochloride.

A bioactive ligand, 2,5-diamino-1,3,4-thiadiazole (L), derived from semicarbazide hydrochloride, and its metal complexes were prepared and characterized. The complexes were characterized using elemental, infra-red, ultraviolet/visible, magnetic moment, atomic absorption, thin layer chromatography and molar conductance measurements. The IR data revealed that the ligand (L) behaved as a tridentate neutral ligand. It coordinated to the metal ion via sulphur and nitrogen of the amines. The molar conductance data reveal that the chelates are non-electrolytes. From the Ultraviolet/Visible spectra and magnetic moment data, the complexes were found to have octahedral geometrical structure. In vivo evaluation of the antimicrobial activities of the metal complexes and the ligands showed greater activity against some micro-organisms when compared to the parent compounds. The chelates do not show toxicity against the activities of enzymes from homogenates of liver, kidney and serum in experimental rats.

Organotin Compounds. I. The Synthesis of Some Dibutyltin and Dibenzyltin Azides and Sulfonates

Abstract SUMMARY The reactions of dibutyltin dichloride and dibenzyltin dichloride with sodium azide, sodium p-toluenesulfonate and silver trifluoromethanesulfonate have been investigated. The products of these reactions include the expected dialkyltin azides and p-toluenesulfonates. In the reactions involving silver trifluoromethanesulfonate, the dialkyltin dichlorides gave only the 1,1,3,3-tetraalkyl-1,3-bis (trifluoromethanesulfonato)- distannoxanes. Other distannoxanes containing the azide and trifluoromethanesulfonato groups attached to tin were also prepared. The infrared spectra and the conductivity characteristics of these compounds are discussed.

Copper(II) Complexes of 4, 4- Diaminodiphenylsulphone: Synthesis, Characterization and Biological Studies

Five complexes of copper(II) 4,4-diaminodiphenylsulphone have been synthesized. Copper salts of counter ion (sulphate, nitrate, chloride) and different reaction media (solvents) were used for the synthesis. The complexes varied in colour and composition. The compounds were characterized by conductivity, IR, UV, NMR and mass spectroscopies. The ligand coordinated to metal ion in a monodentate and bidentate manner. All the five complexes have tetrahedral configuration. The biological activities data showed that the complexes are more active against Esherichia coli , Klebbsiella pneumoniae and Staphylococcus aureus than the free ligand (4,4- diaminodiphenyl sulphone). Antimalaria activities of the complexes and the ligand were investigated using mice infected with Plasmodium berghei . All the complexes exhibited lower activity than the ligand and chloroquine. The effect of administration of the complexes on alkaline phosphatase activities of kidney, liver and serum of Albino rats were investigated. The serum ALP activity showed no significant change (P> 0.05), suggesting non-damaging effect on the plasma membrane of liver and kidney cells.

Synthesis and Characterization of Some Metal Complexes of Vitamin C. Part 21—Ascorbate Complexes of Mn(II), Fe(III) and Co(II)

Abstract Previously we reported the synthesis and characterisation of vitamin C complexes of Cu(II) and Zn(II) metal ions1. In this work, we have synthesised and characterised vitamin C metal complexes of Mn(II), Fe(III) and Co(II) by elemental analyses, magnetic moments, i.r. and u.v. spectral studies. The ascorbic acid was bidentate in its mode of complexation and binds through the carbonyl and C-2 enolic hydroxy groups. All the complexes prepared were paramagnetic and possess an octahedral structure.

Some nontoxic metal-based drugs for selected prevalent tropical pathogenic diseases

Metal coordination of bioorganic compounds from both natural and synthetic products is not only gaining recognition in drug design and medicinal inorganic chemistry research, also they are being considered in the improvement of the bioactivity of drugs. What is done in this paper is a review of recent advances in the study of coordination-driven drug delivery, i.e., metal-based drugs (MBDs). The role of some late first row transition metal ions namely Fe, Cu and Zn in the biological activities of metallodrugs such as antimalarials and antimicrobials are highlighted. It was revealed that the interaction between these bio-essential transition metal ions and the organic drugs could enhance the diagnostic and therapeutic potentials of such formed drugs. This is because such interactions were proved to have improved the stability, bioavailability and cell delivery functions of the metallodrugs. Emphasizing on the challenge of metal ions toxicity, the researchers concluded on the need for the development of MBDs to combat drug resistant parasites without causing injury to normal cells. This would be of significance in addressing the concern World Health Organisation of ameliorating the increasing mortality rate in developing countries.

Pentafluorophenylbromine(III) difluoride

Abstract Pentafluorophenylbromine(III) difluoride has been prepared by oxidation of pentafluorophenyl bromide at 128°C with elemental fluorine.

Pentafluorophenylbromine(V) tetrafluoride

Abstract Pentafluorophenylbromine(V) tetrafluoride has been prepared by the oxidation of pentafluorophenyl bromide at 128°C with elemental fluorine.

Pentafluorophenylchlorine(III) difluoride

Abstract Pentafluorophenylchlorine(III) difluoride has been prepared by the oxidation of pentafluorophenyl chloride at 117°C with elemental fluorine.

Metal Complexes as Prospective Antibacterial Agents

Ninety elements occur naturally on earth. Out of these, nine are radioactive and among the remaining eighty one that could support life, sixty one are metals. Our bodies are 3% metal. Thus, it is surprising that some of the most serious challenges to human life, externally, the pollutants cadmium, mercury and lead are attracting more attention, whereas internally, there is a constant battle against sodium and calcium that are rejected by cells and accumulated elsewhere in the body during the ageing process. Furthermore, some diseases release metals into the blood stream. Their use in the fight against diseases was first described by Schubert in 1965. Man just like other vertebrates requires cations of the metals to facilitate a great many essential life processes. Moreover, many of the metals are essential for all other forms of life process. Around 5000 years ago the Egyptians used copper metal to sterilize water and gold was used in a variety of medicines in Arabian and China, but the practice emanated from the value of pure metal rather than from therapeutic effects.

Synthesis of 1,2 difluoro-1,2-bis(pentafluorophenyl)dichlorane

Abstract 1,2-Difluoro-1,2-bis(pentafluorophenyl)dichlorane is a new class of organic polyvalent chlorine compound. The closeness of the retention time of this compound and that of chloropentafluoro- benzene made its purification difficult. All attempts to obtain this compound in high yield have failed. 1,2-Difluoro-1,2-bis- (pentafluorophenyl)dichlorane is prepared by fluorination of chloropentafluorobenzene at 128°C with elemental fluorine. It has been characterized by 19 F n.m.r., i.r., mass spectroscopy and elemental analysis.