N-(Benzothiazol-2-yl)-4-chlorobenzenesulphonamide (NBTCS) was synthesized by condensation reaction of 4-chlorobenzenesulphonyl chloride and 2-aminobenzothiazole in acetone under reflux. Neodymium(III) and thallium(III) complexes of the ligand were also synthesized. Both ligand and metal complexes were characterized using UV-Vis, IR, 1H- and 13C-NMR spectroscopies, elemental analysis and molar conductance measurement. IR studies revealed that the ligand is tridentate and coordinates to the metal ions through nitrogen and oxygen atoms of the sulphonamide group and nitrogen atom attached to benzothiazole ring. The neodymium(III) complex displays a coordination number of eight while thallium(III) complex displays a coordination number of six. The ligand and its complexes were screened in vitro for their antibacterial activities against Escherichia coli strains (E. coli 6 and E. coli 13), Proteus species, Staphylococcus aureus and Pseudomonas aeruginosa using the agar well diffusion technique. The synthesized compounds were found to be more active against the microorganisms screened relative to ciprofloxacin, gentamicin and co-trimoxazole.

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Copper(II) complexes of bis(4-hydroxypent-2-ylidene)diaminoethane (BHPDE) were prepared by extractive method. Job’s continuous variation and equilibrium constant methods, as well as spectral and elemental analyses were applied in the determination of the nature of extracted species. The results indicate the formation of mixed ionic complexes of the types Cu(H2L)X2, Cu(H2L)2X2and CuL (where H2L = BHPDE and X = NO3-, CIO4-, Cl-or ½SO42-). Cu(H2L)X2and Cu(H2L)2X2predominate at low pH extractions while CuL chelate predominates at high pH extraction. The complexes exist in two isomeric forms, the blue readily-water-soluble and the violet less water-soluble forms. Both complexes show maximum absorption at 540 nm and molar absorptivity values of about 2.0 x 102dm3mole-1cm-1.

_____________________________________________________________________________Their solubilities and melting points were also determined.

A novel tripodal Schiff base ligand, 5‐amino‐2,4,6‐tris(4‐carboxybenzimino)‐1,3‐pyrimidine (TTPS), was synthesized for the first time by the reaction of 2,4,5,6‐tetraaminopyrimidine with 4‐carboxybenzaldehyde. The ligand was characterized by means of ultraviolet–visible, Fourier transform infrared, one‐dimensional 1H‐NMR, and one‐dimensional 13C‐NMR spectroscopies and elemental microanalysis. The Fourier transform infrared and NMR studies revealed that one of the NH2 group in 2,4,5,6‐tetraaminopyrimidine is not involved in bonding. The in vitro antimicrobial activities of the ligand were investigated against Gram‐negative bacteria: Escherichia coli (ATCC 6749) and Pseudomonas aeruginosa (ATCC 9027), Gram‐positive bacteria: Staphylococcus aureus (ATCC 6538P) and Bacillus cereus (ATCC 14579), and fungi: Candida albicans and Aspergillus niger by the agar well diffusion technique. TTPS exhibits good activity against the test microorganisms. The minimum inhibitory concentrations of TTPS against S. aureus were compared with tetracycline and gentamicin, which are conventional bacterial drugs. The upper level of Lorke's method was used to determine the acute toxicity of the compound. The acute toxicity test indicates that TTPS is toxic at doses above 2154 mg/kg. The in vivo antimalarial assay was carried out on Plasmodium berghei based on the 4‐day suppressive method. The result shows a general dose‐dependent significant parasitemia inhibition compared with the negative control with TTPS having inhibition of 72.20% at 50 mg/kg and 65.81% at 25 mg/kg close to the value (87.22%) of the standard drug artesunate 5 mg/kg. Density functional theory method was used to complement this experimental investigation.

Synthesis, electronic, infrared, elemental micro analytical studies were carried on N-(benzothiazol-2-yl)trichloroethanamide [4] and N-(benzothiazol-2-yl)chloroethanamide [5]. They were also screened in vitro and in vivo for antibacterial activity. The results indicate that the compounds are very stable and that they show high antibacterial activities against both grampositive and gram-negative bacteria tested. Both derivatives of 2-aminobenzothiazole were active against the multiresistant bacteria with IZD ranging from 9 -18 mm [5] and 9 – 20mm [4]. From the MIC results it is observed that the [5] derivative produced a better antibacterial activity than the [4] derivative. The lethal concentrations (LC50) of the compounds were also determined. Their solubilities and melting points were also determined.

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