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The antimicrobial activities of eleven maleimide derivatives were tested in this study. Out of the eleven samples, N-(4fluorophenyl) maleimide, N-(4-chlorophenyl) maleimide and N-(4-bromophenyl) maleimide were synthesized by reacting maleic anhydride with 4-fluorophenylaniline, 4-chlorophenylaniline and 4-bromophenylaniline, respectively in the presence of acetic acid, by refluxing overnight. Crystals were successfully obtained after the products were recrystallized with different mixture of solvents. Their chemical structures were confirmed by infrared spectroscopy (IR), H and C Nuclear Magnetic Resonance (NMR) and melting point determination. Subsequently, all the samples were screened for their biological activity using disc diffusion method. The bacteria chosen for this study were Gram-negative Escherichia coli, Gram-positive Bacillus subtilis and yeast Saccharomyces cerevisae. Positive control for bacteria was streptomycin and nystatin for the yeast. M1 to M6 compounds gave remarkable result at low concentrations whereas M8, M9 and M11 compounds are mostly inactive up to a high concentration. In contrast, the unsubstituted maleimide, M7 was highly reactive towards both bacteria and yeast at low and high concentrations.

Thioureas play an important role in medicinal chemistry and agricultures due to their biological activity such as antibacterial, antifungal, antiviral, herbicides, rodenticides, phenoloxidase enzymatic inhibitors, anti-HIV and anti-tumor agents. In this study, five substituted bis-thioureas have been synthesized. The isophataloyl chloride and 2,6pyridinedicarbonyl dichloride were easily converted to bis-isothiocyanate compound via the reaction with ammonium thiocyanate by solid–liquid phase transfer catalysis of polyethylene glycol-400 (PEG-400). Bis-isothiocyanate compound was reacted with aniline derivatives to produce substituted bis-thioureas in good yield at room temperature. All the novel compounds were obtained as yellow solid after recrystallization using DMF/EtOH/H2O. Their c h e m i c a l structures were confirmed by Infrared spectrosopy (IR), Nuclear Magnetic Resonance (NMR) H and C and mass spectrometry. The five synthesized compounds were screened for antimicrobial activities using disc diffusion method for antimicrobial activity against Gram-positive bacteria (Bacillus Subtilis and Staphylococcus Aureus), Gram-negative bacteria (Escherichia Coli and Salmonella Typhi) and a mold (Aspergillus Niger). All tested compounds showed low antimicrobial activity since the diameter of inhibition zone (IZ) measure was less than positive control inhibition zone.