Department of Chemistry (Ch.)

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Synthesis and Antimicrobial Activities of Chromene Derivatives
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2017-05) Islam, Md. Tarikul; Badal, Prof. Dr. Md. Mizanur Rahman
The design and synthesis of chalcone and chromene derivatives and their antibacterial activities were studied in this research. Conveniently, all products were synthesized from commercially available acetophenone, 4-hydroxybenzaldehyde and dimedone. Different synthetic strategies were used to obtain an easily accessible chromene scaffold with appropriate handles. At first, this research work was involved in an efficient procedure for the attachment of 4-hydroxybenzaldehyde and acetophenone in the presence of 10% NaOH to produce 3-(4-Hydroxy-phenyl)-1-phenyl-propenone. 4-{3-[(2,4-Dinitro-phenyl)-hydrazono]-3-phenyl-propenyl}-phenol phenylamine has been synthesized by the reaction of 2,4 dinitro phenyl hydrazine with chalcone. Reaction of dimedone with chalcone under refluxing condensation using dry benzene and zinc chloride as a catalyst to give the corresponding chromene derivative 4-(4-Hydroxy-phenyl)-7,7-dimethyl-2-phenyl-4,6,7,8-tetrahydro-chromen-5-one. This reaction also carried out by Microwave Irradiation and use ethanol as a solvent, without any catalyst. It was found that the preparation time for the compounds was reduced from 72 hours to 5-10 minutes during microwave irradiation. The structures of the all synthesized compounds were characterized by their IR, 1H NMR spectral data. The antibacterial and antifungal activity of the compounds was also investigated. The antimicrobial activity of the compounds at concentration 300 μg/disc was performed against three gram-positive bacteria (Bacillus cereus, Staphylococcus aureus and Listeria monocytogenes) and three gram-negative bacteria (Escherichia coli, Salmonella typhimurium, and citobacteria frundi) by Kirby-Bauer disc diffusion method using Ciprofloxacin as standard. Antifungal screening was carried out against one fungi (Tricodarma harzianum) using Michonazole as standard. Compound, I, 3-(4-Hydroxy-phenyl)-1-phenyl-propenone exhibits no activity against the tested bacterial strains Bacillus cereus, Listeria monocytogenes, Escherichia coli, Salmonella typhimurium, Citrobacter freundii, but showed moderate activity against the tested bacteria Staphylococcus aureus having inhibition zone 8 mm and also show antifungal activity aganist Trichoderma harzianum inhibition zone 10mm. Compound, II, 4-{3-[(2,4-Dinitro-phenyl)-hydrazono]-3-phenyl-propenyl}-phenol exhibits no activity against gram negative, gram positive strains but showed antifungal activity against Trichoderma harzianum inhibition zone 6 mm. Compound, III, 4-(4-Hydroxy-phenyl)-7,7-dimethyl-2-phenyl-4,6,7,8-tetrahydro-chromen-5-one showed activity against Gram positive, Gram negative except Listeria monocytogenes, Escherichia coli, Salmonella typhimurium. This compound, III also showed antifungal activity against Trichoderma harzianum inhibition zone 8 mm.
Synthesis and Spectral Characteristics of Substituted 2,6-Dibenzylidene Cyclohexanone
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2018-05) Islam, Hasan Md. Ashekul; Badal, Prof. Dr. Md. Mizanur Rahman
The design and synthesis of substituted 2,6-Dibenzylidene cyclohexanone based bischalcone derivatives were studied in this research through one of the most important Claisen-Schmidt condensation reaction of donor-acceptor conjugated system and their spectral properties has been studied. A number of substituted 2,6-Dibenzylidene cyclohexanone was synthesized through the reaction of commercially available para substituted benzaldehyde and cyclohexanone in presence of basic NaOH, where NaOH acts as a catalyst. The structures of the synthesized products were characterized by their physical, chemical and UV, IR & 1H NMR spectra. The compounds were soluble in most organic solvents. 2,6-Bis-(4-dimethyl-amino benzylidene)-cyclohexanone showed acidochromic behavior with the change of pH. This compound when interacts with acids changed the color of compounds due to the presence of chromophore. 2,6-Dibenzylidenecyclohexanone 1 absorbed at 330 nm and 2,6-Bis-(4-dimethylamino-benzylidene)- cyclohexanone 5 disclosed high absorption at 452 nm. The bathochromic shifts for compound 5 is due to the presence of electron donating N(CH3)2 substituents and the hypsochromic shifts for compound 1 is mainly due to the basic chalcone framework where no substituent is present. Also 2,6-Bis-(4-methoxy-benzylidene)-cyclohexanone 4 showed absorption at 359 nm (bathochromic shifts, lesser than compound 5) due to the presence of electron donating MeO substituents. Probably the halogen substituent contributed very little effect to the absorption and hence 2,6-Bis-(4-chloro-benzylidene)-cyclohexanone 2 exhibited absorption at 333 nm. Further 2,6-Bis-(4-nitro-benzylidene)-cyclohexanone 3 showed absorption at 340 nm. The solvatochromic behavior study of these compounds revealed that when these compounds were dissolved in different solvents (Ethanol, Ethyl acetate and Dichloromethane) formed hydrogen bonds on the basis of the polarity of the solvent and stabilized the product. EtOH is a polar protic solvent and the polarity of etanol is more than ethyl acetate and dichloromethane hence in case of compounds 1,4 & 5 exposed greater max (bathochromic shifts) in EtOH due to the formation of hydrogen bonds. This shifts turned to hypsochromic from ethyl acetate to DCM as these are aprotic. This could be due to the decrease in energy of the excited state as a function of increase in solvent polarity, which is in the order: DCM < Ethyl acetate < EtOH and stabilized the compound.
Synthesis of Pyrimidine Derivatives and Investigation of their Antimicrobial Activity
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2017-05) Parvin, Reshma; Badal, Prof. Dr. Md. Mizanur Rahman
The research work was involved in an efficient procedure for the attachment of 4- amino acetophenone with benzaldehyde in the presence of 10% NaOH to produce 1-(4-Aminophenyl)-3-phenyl-propenone (I) or arylidine acetophenone. 4-{1-[(2,4-Dinitro-phenyl)-hydrazono]-3-phenyl-allyl}-phenylamine (II) has been synthesized by the reaction of 2,4 DNP with 1-(4-Amino-phenyl)-3-phenyl-propenone. Reaction of barbituric acid with arylidine acetophenone under refluxing condensation using 50% aqueous ethanol which on further reflux to give the corresponding pyrimidine derivatives, 7-(4-Amino-phenyl)-5-phenyl-1, 5-dihydro-pyrano [2, 3-d] pyrimidine-2, 4-Dione (III). The structures of the synthesized compounds were characterized by their IR, NMR spectral data. The antibacterial and antifungal activity of the compounds was also investigated. The antimicrobial activity of the compounds at concentration at 300μg/disc was performed against three gram-positive bacteria (Bacillus cereus, Staphylococcus aureus and Listeria monocytogenes) and three gramnegative bacteria (Escherichia coli, Salmonella typhimurium, and citobacteria frundi) by Kirby-Bauer disc diffusion method using Ciprofloxacin as standard. Antifungal screening was carried out against one fungi ( Tricodarma harzianum) using Michonazole as standard. Compound I, 1-(4-Amino-phenyl)-3-phenyl-propenone exhibits no activity against the tested bacterial strains but showed moderate activity against the tested fungi Trichoderma harziniaum having inhibition zone 11 mm. Compound III, 7-(4-Amino-phenyl)-5-phenyl- 1,5-dihydro-pyrano[2,3-d] pyrimidine-2,4-Dione exhibits broad spectrum activity against both gram negative and gram positive strains tested except Listeria monocytogenes. Also the compound II, 4-{1-[(2,4-Dinitro-phenyl)-hydrazono]-3-phenyl-allyl}-phenylamine showed promising antibacterial activity having inhibition zone of 24 mm against Ctirobacteria freundi having no antifungal activity. Those bacteria revealed the zone of inhibition were 11-24 mm. The presence of an amino and unsaturated ketone function in synthesized compound may be responsible for their antibacterial and antifungal activity.
Synthesis, Characterization and Structural Optimization Using Density Functional Theory of Hydrazone Schiff Base Derivatives
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2019-01) Hossain, Md. Zakaria; Badal, Prof. Dr. Md. Mizanur Rahman
This thesis paper is related in an effective method for the addition of 2,4-dinitrophenyl hydrazine and various substituted 2,6-dibenzylidene cyclohexanone based bis-chalcones in the presence of hydrochloric acid to produce various hydrazone Schiffbase derivatives. First product, N[2,6bis(4:chlorobenzylidene)cyclohexylidene]-N'-(2,4-dinitrophenyl)-hydrazine has been synthesized by the reaction of 2,4-dinitrophenyihydrazine with 2,6-bis-(4-chlorobenzylidene)-cyclohexanone at reflux conditionat 2 hours. The isolated product was red in color and the melting point of the pure product was 185 °C. Second synthesized product. N-[2,6-bis-(4-methoxy-benzylidene)-cyclohexylidene]-N'-(2,4-dinitrophenyi)-hydrazifle has been synthesized by the reaction of 2,4-dinitrophenyl hydrazine with 2,6-bis-(4-methoxybenzylidene)-cyclohexanone at the same condition. The pure product was coffee color and the melting point of the pure product was 225 °C. Final product, N-[2,6-bis-(4-dirnethylamino-benzylidene)-cyclohexylidene]-N'-(2,4-dinitrophenyl)-hydrazifle has been synthesized by the reaction of 2,4-dinitrophenyihydrazine with 2,6-bis-(4-dimethylbenzylidene)-cyclohexanone also at the same condition. The product of the color was black and the melting point of the pure product was 245 °C. The structures of the synthesized products were characterized by their physical, UV, FTIR, 'H NMR & '3C NMR spectra. Their optimized structures have been investigated by computational method, Gaussian 16 software Revision B.01. Their molecular geometry and vibrational frequencies were computed at density functional theory, DFT-133LYP/6-3 1 1+G (2d, p) level of theory.