Macrocyclic Schiff Base Metal Complexes Derived from Isatin: Structural Activity Relationship and DFT Calculations

Macrocyclic metal complexes viz., Co(II), Ni(II), Cu(II) and Zn(II) have been prepared using a macrocyclic Schiff base as ligand, which was derived from Isatin, 4-aminoantipyrine and o-phenylenediamine. Further, the complexes have been characterized by elemental analysis, magnetic susceptibility, molar conductance, mass spectrometry, FT-IR-, Far-IR-, UV-Vis-, EDX spectroscopy, 1H NMR and 13C NMR, ESR spectroscopy and SEM. The octahedral geometry of the complexes has been revealed by the spectral data of UV-Vis and ESR as well as by the results of the magnetic susceptibility measurements. Antimicrobial screening tests indicated that the Zn(II) metal complexes showed an excellent antimicrobial activity compared to the other studied metal complexes. The nuclease activity of the metal complexes showed that the Co(II) complex has effectively cleaved DNA. The optimized molecular structure, bond length, bond angle, dihedral angle, chemical reactivity and total energy have been evaluated using the density functional theory (DFT) with B3LYP functional level.

Synthesis of novel derivatives of oxindole, their urease inhibition and molecular docking studies

We synthesized a series of novel 5-24 derivatives of oxindole. The synthesis started from 5-chlorooxindole, which was condensed with methyl 4-carboxybezoate and result in the formation of benzolyester derivatives of oxindole which was then treated with hydrazine hydrate. The oxindole benzoylhydrazide was treated with aryl acetophenones and aldehydes to get target compounds 5-24. The synthesized compounds were evaluated for urease inhibition; the compound 5 (IC50 = 13.00 ± 0.35 μM) and 11 (IC50 = 19.20 ± 0.50 μM) showed potent activity as compared to the standard drug thiourea (IC50 = 21.00 ± 0.01 μM). Other compounds showed moderate to weak activity. All synthetic compounds were characterized by different spectroscopic techniques including (1)H NMR, (13)C NMR, IR and EI MS. The molecular interactions of the active compounds within the binding site of urease enzyme were studied through molecular docking simulations.

Influence of the diversified structural variations at the imine functionality of 4-bromophenylacetic acid derived hydrazones on alkaline phosphatase inhibition: synthesis and molecular modelling studies

Putative binding mode of 4g inside the active pocket of h-PLAP.

Crystal structure of (E)-N'-benzyl-idene-2-meth-oxy-benzohydrazide

In the title benzoyl-hydrazide derivative, C15H14N2O2, the dihedral angle between the planes of the two phenyl rings is 12.56 (9)°. The azomethine double bond adopts an E configuration stabilized by an N-H⋯O hydrogen bond. In the crystal, the components are linked by C-H⋯O inter-actions to form chains along the b axis.

(E)-3-Chloro-N'-(2-fluoro-benzyl-idene)thio-phene-2-carbohydrazide

The title compound, C₁₂H₈ClFN₂OS, is a hydrazide derivative adopting an E conformation with an azomethine N=C double bond length of 1.272 (2) Å. The mol­ecular skeleton is approximately planar; the terminal five- and six-membered rings form a dihedral angle of 5.47 (9)°. In the crystal, mol­ecules are linked by N—H⋯O and C—H⋯O hydrogen bonds into zigzag chains propagating in [100].

Phenoxyacetohydrazide Schiff bases: β-glucuronidase inhibitors

Phenoxyacetohydrazide Schiff base analogs 1–28 have been synthesized and their in vitroβ-glucouoronidase inhibition potential studied. Compounds 1 (IC₅₀ = 9.20 ± 0.32 µM), 5 (IC₅₀ = 9.47 ± 0.16 µM), 7 (IC₅₀ = 14.7 ± 0.19 µM), 8 (IC₅₀ = 15.4 ± 1.56 µM), 11 (IC₅₀ = 19.6 ± 0.62 µM), 12 (IC₅₀ = 30.7 ± 1.49 µM), 15 (IC₅₀ = 12.0 ± 0.16 µM), 21 (IC₅₀ = 13.7 ± 0.40 µM) and 22 (IC₅₀ = 22.0 ± 0.14 µM) showed promising β-glucuronidase inhibition activity, better than the standard (D-saccharic acid-1,4-lactone, IC₅₀ = 48.4 ± 1.25 µM).

Synthesis, crystal structure, DFT studies and evaluation of the antioxidant activity of 3,4-dimethoxybenzenamine schiff bases

Schiff bases of 3,4-dimethoxybenzenamine 1-25 were synthesized and evaluated for their antioxidant activity. All the synthesized compounds were characterized by various spectroscopic techniques. In addition, the characterizations of compounds 13, 15 and 16 were supported by crystal X-ray determinations and their geometrical parameters were compared with theoretical DFT calculations at the B3LYP level of theory. Furthermore, the X-ray crystal data of two non-crystalline compounds 8 and 18 were theoretically calculated and compared with the practical values of compounds 13, 15, 16 and found a good agreement. The compounds showed good DPPH scavenging activity ranging from 10.12 to 84.34 μM where compounds 1-4 and 6 showed stronger activity than the standard n-propyl gallate. For the superoxide anion radical assay, compounds 1-3 showed better activity than the standard.

Synthesis of 4-methoxybenzoylhydrazones and evaluation of their antiglycation activity

A series of 4-methoxybenzoylhydrazones 1-30 was synthesized and the structures of the synthetic derivatives elucidated by spectroscopic methods. The compounds showed a varying degree of antiglycation activity, with IC50 values ranging between 216.52 and 748.71 µM, when compared to a rutin standard (IC50=294.46±1.50 µM). Compounds 1 (IC50=216.52±4.2 µM), 3 (IC50=289.58±2.64 µM), 6 (IC50=227.75±0.53 µM), 7 (IC50=242.53±6.1) and 11 (IC50=287.79±1.59) all showed more activity that the standard, and these compounds have the potential to serve as possible leads for drugs to inhibit protein glycation in diabetic patients. A preliminary SAR study was performed.

(E)-N′-(3,4-Dihydroxybenzylidene)-2,4-dimethylbenzohydrazide monohydrate

In the title compound, C₁₆H₁₆N₂O₃·H₂O, the dihedral angle between the benzene rings is 30.27 (7)°. In the crystal, the components are linked by N—H⋯O, O—H⋯O and C—H⋯O inter­actions into a three-dimensional network.