Metal schiff base complexes of tridentate antipyrine based ligand: Synthesis, spectral characterisation, image analysis and biological studies

Preparation, Spectral Characterization and Antioxidant Activities of Aminothiophene-Containing Schiff Base and Co(II) and Pd(II) Complexes

This research focused on synthesizing a Schiff base (L) and its Co(II) and Pd(II) complexes under appropriate conditions to contribute to enhancing antioxidant activity. The ligand was synthesized by reacting methyl 2-amino-4-ethyl-5-methylthiophene-3-carboxylate with 5-bromo-2-hydroxybenzaldehyde. Various analytical techniques were employed to characterize the ligand and its resulting complexes, including microanalysis, 1H and 13C NMR spectroscopy, FTIR, electronic spectra, mass spectrometry, magnetic susceptibility, molar conductance, and thermo-gravimetric analysis. Electronic spectra and magnetic moment values were used to confirm the geometric structures of the synthesized compounds. Thermo-gravimetric analyses (TGA-DTA) were conducted to evaluate the thermal stability of the complexes. The Pd(II) complex was found to have a square planar structure, while a tetrahedral structure was suggested for the Co(II) complex. The results from the elemental analysis were consistent with both the ligand and metal complexes, showing good agreement between calculated and experimental values. The in vitro antioxidant activities of the newly synthesized compounds were examined using different antioxidant methods. Experiment results exhibited that the Pd(II) complex had better activities than the Schiff base and Co(II) complex. According to ABTS experimental results, Pd(II) complex (IC50:1.25) showed similar activity to the standards. In contrast, CUPRAC results revealed that Pd(II) complex (7.55 µg TE/mL) showed better activity than the standards. The results indicate that Pd(II) complex has strong potential as effective antioxidants, making them valuable for food and medicine applications.

Design, Synthesis and Antibacterial Assessment of Active (4-Arylazo-3-Methyl-2-Thienyl) 4-Antipyrine Ketones

The chemicals formed from antipyrines are flexible organic building blocks that are employed in the development of pharmaceuticals. By diazotizing (4-arylazo-3-hydroxy-2-thienyl) 4-antipyrine ketones 1a, 1b and 1c and (4-arylazo-3-methyl-2-thienyl) 4-antipyrine ketones (2a, 2b and 2c) further replaced with six other coupling components, a broad spectrum of hybrid molecules have been created. Mass spectra, NMR, FTIR, and elemental analyses have all been used to confirm the structures of the synthesised compounds. The antimicrobial screening was investigated by agar well diffusion and diluting the broth technique against both Gram-negative and positive-tested bacterial strains. (3-methyl-5-(phenylamino)-4-(4-tolylazo)-2-thienyl) 4-antipyrine ketone (2a) was found to be superior to Ciprofloxacin against test strains: Acinetobacter sp (34.33±1.15 mm), Listeria monocytogenes (29.33±1.15 mm) and Streptococcus sp. (19.33±1.15 mm). Also, good to moderate activities were expressed as minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) which were recorded at 9±1 to 59.67±4.51 μg/mL and 16±4 to >512 μg/mL, respectively, using compounds 2a, 2b, and 2c. MBC/MIC ratio showed, that only, 2a and 2b have a bactericidal effect but other antipyrines with bacteriostatic strength. To conclude, it was suggested that the use of these novel synthesized (4-arylazo-3-methyl-2-thienyl) 4-antipyrine ketone derivatives molecules as a new chemical class of antimicrobial agents to perform new drug discovery in pharmaceutical preparations and medicinal research.

Synthesis and characterization of the new ligand, 1,2,4-triazino[5,6-b]indol-3-ylimino methyl naphthalene-2-ol and its Ni(II) and Cu(II) complexes: comparative studies of their in vitro DNA and HSA Binding

A new ligand 1,2,4-triazino[5,6-b]indol-3-ylimino methyl naphthalene-2-ol (HL) was derived from 5H-[1,2,4]triazino[5,6-b]indol-3-amine and 2-hydroxy-1-naphthaldehyde. The metal complexes of the type [Ni(L)(Bipy)]1/2SO₄ (1), [Cu(L)(Bipy)(H₂O)₂]1/2SO₄ (2), [Ni(L)(Phen)]1/2SO₄ (3) and [Cu(L)(Phen)(H₂O)₂]1/2SO₄ (4) were synthesized. The ligand (HL) and complexes 1-4 were thoroughly characterized by elemental analysis and spectroscopic methods (FT-IR, ToF-MS, ¹H NMR, ¹³C NMR), molar conductance and magnetic moment determination. The Ni(II) complexes 1 and 3 adopt the square planar geometry and Cu(II) complexes 2 and 4 acquire distorted octahedral arrangement. In vitro DNA binding behavior of ligand (HL) and metal complexes 1-4 was explored by fluorescence spectral and ethidium bromide studies. The outcomes reveal that the complexes interact with DNA via non-covalent groove binding and electrostatic interactions. The higher binding constant (K) values of 4.35 × 10⁴ and 9.12 × 10⁴ M^-1 for complexes 2 and 4 indicate stronger binding ability with DNA. Moreover, in vitro human serum albumin (HSA) binding experiment with HL and complexes 1-4 reveals conformational modulations in the Trp-214 microenvironments in the subdomain IIA pocket.