Synthesis, structural characterization, and in vitro biological activity studies of ternary metal complexes of 1,10‐phenanthroline and the anti‐inflammatory bromhexine drug

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Novel thiophene Schiff base ligand (L) was synthesized through the condensation of 2‐thiophene‐methylamine and 3‐formyl‐4‐methoxyphenylboronic acid. Transition metal complexes with the formulae [M(L)(H2O)2Cl]Cl2.xH2O (M = Er(III), x = 4 and La(III), x = 5) and [M(L)(H2O)Cl2]Cl.xH2O (M = Yb(III), x = 4 and Ru(III), x = 0) were synthesized. Different spectral and physicochemical methods were used to confirm and identify the stoichiometry, structure, and bonding style of transition metal chelates. The creation of 1:1 molar ratio (M:L) complexes was supported by elemental data. According to IR spectra, the thiophene Schiff base ligand (L) acted as a tridentate ligand that is neutrally coordinated by S‐thiophene, N‐azomethine, and o‐methoxy groups. All chelates formed in octahedral structures according to the findings data. Thermogravimetric analysis (TG and DTG) was employed to examine the heat decomposition of these compounds. DFT/B3LYP method, a molecular modeling methodology, is used to support the expected shape of the produced ligand. Chemical hardness and softness, HOMO and LUMO energy levels, electrophilic index, bond lengths, angles, dipole moment, electronegativity, and other factors were calculated. Against HepG‐2 cell line, the in vitro anticancer activity of all chelates and free ligands was evaluated. These synthesized compounds showed good effectiveness. Additionally, DPPH scavenging was used to assess antioxidant activity, with extremely positive results. Molecular docking with the hepatic protein receptor 3ELJ was used to confirm the anticancer results. Finally, the effectiveness of the current thiophene ligand's ability to block Al‐Si alloys in 1 M HCl solution was examined utilizing electrochemical methods. The high inhibition efficiency was obtained revealing the effectiveness of using this thiophene Schiff base ligand on an industrial scale.

Preparation, characterization, and computational study on transition metal complexes derived from thiophene Schiff base and evaluation of their cytotoxicity against hepatic cell line, antioxidant activities, and ligand's anticorrosive properties

Sayed,

Ashmawy,

Mohamed

et al. 2024

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Analyzing the structure of the metal complexes of biologically active azo dye ligand

Saleh,

El‐Sayed,

Zayed

et al. 2024

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A novel azo dye ligand was created by diazotizing 4‐aminoantipyrine and then coupling it with 2‐aminophenol as part of a methodical investigation of physiologically active compounds, 4‐aminoantipyrine. The novel complexes containing Cr(III), Fe(III), Mn(II), Co(II), Ni(II), Zn(II), Cu(II), and Cd(II) were created from the target ligand (L). The structures of the ligand and metal complexes were verified by elemental analyses, thermogravimetric analysis–difference thermogravimetry (TGA‐DTG), conductivity measurements, infrared (IR), UV–Vis, 1H‐nuclear magnetic resonance (NMR), X‐ray diffraction (XRD), and mass spectrometry. Using the Gaussian 09 tool, the density functional theory (DFT)/B3LYP method was utilized to compute the energy gaps and other important theoretical features. Also, the newly synthesized azo dye ligand, in comparison with metal complexes, was screened for its antimicrobial activity. The crystal structures of Staphylococcus aureus and Bacillus subtilis as gram‐positive bacteria, Salmonella sp. and Escherichia coli as gram‐negative bacteria, and fungal (Aspergillus fumigatus and Candida albicans) species were compared with the produced azo dye and its metal complexes via molecular docking. Most of the complexes exhibited greater antimicrobial activities against these organisms than did the original azo dye ligand.

Design, characterization, and different applications of naphthoquinone‐based Schiff base and its M(II/III) complexes with molecular modeling studies

Saleh,

Alminderej,

El‐Sayed

et al. 2024

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Due to the significant pharmacophoric role of 1,4‐naphthoquinone moiety, which is found in numerous biologically active natural products and well‐known chemotherapeutic drugs, including doxorubicin, shikonin, and alkannin, a newly prepared ligand ((E)‐1‐((2‐mercaptophenyl)imino)naphthalen‐2(1H)‐one) can be obtained from the condensation of 2‐aminothiophenol with diketone (1,2‐naphthoquinone) to form Schiff base (HL), which has been characterized using elemental analyses, FT‐IR, 1H‐NMR, and mass spectra. The inner ((La(III), Er(III), and Yb(III)) and outer ((Fe(III), Co(II), and Zn(II)) transitionmetal complexes have been prepared in 1:2 ratio and identified by several spectroscopic instruments. Different characterization tools have been used as elemental analyses, 1H‐NMR, molar conductivity, 13C‐NMR, FT‐IR, thermal decomposition (TG and DTG), UV‐vis, X‐ray diffraction, mass spectrometry, solid reflectance, and magnetic moment. All of them are conjugated to confirm the proposed structures of the metal complexes and are complementary. Also, molecular docking studies for the ligand and its Zn(II) and Yb(III) complexes (using MOE program) have been performed to support the experimental biological activity. Molecular docking studies recommended that (Yb(HL)2)Cl3·6H2O complex is more potent against Aspergillus niger fungus when docked with 1Y43 (aspergilloglutamic peptidase enzyme from A. niger) receptor, while Zn(II) complex recorded the strongest binding energy among the docked compounds against 2W3Z(the crystal structure of a Streptococcus mutans CE4 esterase) and 7AB4 (the crystal structure of the Escherichia coli toxin‐antitoxin system HipBST [HipT S59A]) proteins receptors, respectively. Experimental applications of the free ligand and its metal chelates as antimicrobial and antioxidant activities have been carried out. The former occurred against two fungal species (Aspergillus niger [ATCC:16404] and Candida albicans [ATCC:10231]), two G‐positive bacterial species (S. mutans [ATCC:25175] and Staphylococcus aureus [ATCC:13565]) and two G‐negative bacterial species (Klebsiella pneumonia [ATCC:10031] and E. coli [ATCC:10536]). The DPPH scavenging method has been used to measure the antioxidant activity of the tested compounds.