Investigation of Dipodal oxy-Schiff base and its salen and salophen Fe(III)/Cr(III)/Mn(III) Schiff bases (N2O2) caped complexes and their magnetic and thermal behaviors

Elucidation of the Microwave-Assisted Synthesis and Characterization of Heteronuclear Complexes of Bisbenzimidazole Derivatives and Their Biological Activities by In Vitro and In Silico Assays

A novel and efficient protocol for the microwave-assisted synthesis of diversely substituted 2,2'-bisbenzimidazol-5,6'-dicarboxylic acid (BIMCA) from the reaction of 3,4-diaminobenzoic acid with oxalic acid has been developed, which proceeds through sequential nucleophilic addition and electrophilic substitution in accordance with the Philips method. The synthetic utility of this strategy was demonstrated by the concise, one-pot synthesis of (BIMCA) and metal complexes. (BIMCA) with a [{Fe(salen)}2O] Schiff base ligand complex and new benzimidazole coordination compounds with double oxygen [(BIMCA){Fe(salen)}2] ligand complexes were obtained. The resulting [(BIMCA){Fe(salen)}2] ligand complex was then synthesized from Co(CH3COO)2.4H2O, Ni(CH3COO)2.4H2O and Cu(CH3COO)2.H2O heteronuclear complexes. The condensations proceed with good yield to give products that, in certain instances, are not readily attainable by conventional condensation techniques. The structures of the compounds were identified by Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR), elemental analysis and magnetic susceptibility. The mutagenic potential of the synthesized chemicals was evaluated by the Ames test towards mutant Salmonella typhimurium strains TA98 and TA100. It was recorded that these chemicals had no mutagenic action. Also, antimicrobial activities were screened by broth microdilution test. It was seen that the minimum inhibitory concentration (MIC) against Klebsiella pneumoniae, Staphylococcus aureus and Staphylococcus epidermidis was 0.195 mg/mL, followed by a MIC value of 0.390 mg/mL against Escherichia coli and Salmonella typhimurium. [(BIMCA){Fe(salen)}2Co(II)] demonstrated significant antimicrobial activity against Proteus mirabilis and Staphylococcus aureus, with an MIC of 0.195 mg/mL, followed by an MIC of 0.390 mg/mL against Pseudomonas aeruginosa, K. pneumonia and Salmonella typhimurium. The antioxidant properties were examined using various chemical assays, and [(BIMCA){Fe(salen)}2O] and (BIMCA) exhibited greater 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability, when compared with other compounds. Enzyme inhibitory effects were tested against acetylcholinesterase (AChE), amylase, butyrylcholinesterase (BChE) and tyrosinase. [(BIMCA){Fe(salen)}2Cu(II)] displayed the best AChE (IC50 0.51 mg/mL), BChE (IC50 0.51 mg/mL) and tyrosinase (IC50 1.52 mg/mL) inhibitory effects. Furthermore, molecular docking calculations were performed to gain insights into the interaction between [(BIMCA){Fe(salen)}2] and AChE, and between [(BIMCA){Fe(salen)}2Cu(II)] and amylase. Both compounds showed the potential inhibition of the protein targets.

Orto-hydroxy bioactive schiff base compounds: Design, comprehensive characterization, photophysical properties and elucidation of antimicrobial and mutagenic potentials

Preparation and comprehensive characterization of three Schiff base ligands; with trimethoxy substitution (1E,1'E)-N,N'-(naphthalene-1,5-diyl)bis(1-(3,4,5-trimethoxyphenyl)methanimine, 1, with ortho-hydroxy substitution 6,6'-((1E,1'E)-(naphthalene-1,5-diylbis(azaneylylidene))bis(methaneylylidene))bis(2-methoxyphenol), 2 and 3,4-bis(((E)-2-hydroxy-3-methoxy benzylidene)amino)benzoicacid, 3 and their Ni(II), Cu(II), Co(II), Zn(II), Fe(II), Mn(II) complexes have been reported. Their spectral properties were studied in solution and solid-state by a combination of different analytical techniques; FT-IR spectroscopy, ¹H NMR and ¹³C NMR spectroscopy, elemental analysis and thermal analysis. Diamagnetic and paramagnetic natures of the complexes were also determined by magnetic susceptibility measurements in solid-state. Promising photophysical properties were observed as; A_max. were recorded at 226 nm for 2; at 795 nm for 2-Ni, at 782 nm for 2-Cu, at 784 nm for 2-Co, at 702 nm for 2-Zn, at 784 nm for 2-Fe, at 702 nm for 2-Mn and at 289 nm for 3, at 786 nm for 3-Ni, at 797 nm for 3-Cu, at 746 nm for 3-Co, at 794 nm for 3-Zn, at 699 nm for 3-Fe, at 781 nm for 3-Mn ; and I_max were also recorded at; 380, 490, 725 nm for 2 and 2-Metal; 375 nm, 510 nm, 725 nm for 3 and 3-Metal when excitated at 220 nm. Antibacterial activities against different microorganisms; Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC 70603, Staphylococcus aureus ATCC 43,300 (MRSA), Salmonella enteritidis ATTC 13076, Sarcina lutea ATCC 9341, Bacillus cereus ATTC 11778, and antifungal activities against Candida albicans NRRL Y-417 of the compounds 1, 2, 3, 2-Cu, 2-Fe, 3-Zn, 3-Fe were determined. Mutagenic properties of the compounds were also studied and according to the results 2-Cu and 3 have been found non-mutagenic in Ames test but also they have strong antimicrobial potential against pathogen microorganisms. For 2-Cu MIC values were ranging between 0.39 and 0.024 mg/ml and the lowest minimum inhibitory concentration (0.024 mg/ml) was determined against E. coli. The 3 numbered compound revealed strong antimicrobial activity at doses of ranging between 0.39 and 0.097 mg/ml and E. coli was the most sensitive bacterium against this chemical.

Microwave Irradiation Assists the Synthesis of a Novel Series of bis-Arm s-Triazine Oxy-Schiff Base and Oxybenzylidene Barbiturate Derivatives

A novel series of s-triazines incorporating 4-hydroxybenzaldehyde and 4-hydroxy-3-methoxybenzaldehyde was prepared and fully characterized. The reaction was carried out via stepwise nucleophilic aromatic substitution of chlorine atoms in cyanuric chloride. The first chlorine was substituted by different amines (morpholine, piperidine, or diethylamine) to afford 2,4-dichloro-6-substituted-1,3,5-triazine. The second and third chlorines were substituted by benzaldehyde derivatives in the presence of Na₂CO₃ as a HCl scavenger to afford the target products: s-triazine oxyaldehyde derivatives (dipodal). The dipodal derivatives were reacted with acid hydrazide, hydralazine, barbituric, or thiobarbituric acid derivatives using conventional heating or microwave irradiation to afford the di-arm s-triazine oxy-Schiff base and oxybenzylidene barbiturate derivatives in good yields. Microwave irradiation done in less solvent afforded the target product in less reaction time with good yield and purity. These types of derivatives might have special interest in coordination and medicinal chemistry.