R.N. Jadeja

Synthesis, spectroscopic characterization and DNA nuclease activity of Cu(II) complexes derived from pyrazolone based NSO-donor Schiff base ligands.

Two neutral mononuclear Cu(II) complexes have been prepared in EtOH using Schiff bases derived from 4-toluoyl pyrazolone and thiosemicarbazide. Both the ligands have been characterized on the basis of elemental analysis, IR, (1)H NMR, (13)C NMR and mass spectral data. The molecular geometry of one of these ligands has been determined by single crystal X-ray study. It reveals that these ligands exist in amine-one tautomeric form in the solid state. Microanalytical data, Cu-estimation, molar conductivity, magnetic measurements, IR, UV-Visible, FAB-Mass, TG-DTA data and ESR spectral studies were used to confirm the structures of the complexes. Electronic absorption and IR spectra of the complexes suggest a square-planar geometry around the central metal ion. The interaction of complexes with pET30a plasmid DNA was investigated by spectroscopic measurements. Results suggest that the copper complexes bind to DNA via an intercalative mode and can quench the fluorescence intensity of EB bound to DNA. The interaction between the complexes and DNA has also been investigated by agarose gel electrophoresis, interestingly, we found that the copper(II) complexes can cleave circular plasmid DNA to nicked and linear forms.

Synthesis and spectral characterization of Cu(II) complexes of some thio-Schiff bases of acyl pyrazolone analogues

A series of tridentate pyrazolone-based thio-Schiff bases were synthesized by the interaction of 4-acyl/aroyl pyrazolones with thiosemicarbazide in an ethanolic medium. All of these ligands were characterized on the basis of elemental analysis, infrared (IR), 1H- and 13C-NMR data. Nuclear magnetic resonance (NMR) suggests the amine-one form of ligand in solution at room temperature. Copper Schiff-base complexes, [Cu(L)(H2O)], have been prepared by the interaction of the aqueous solution of copper sulfate pentahydrate with hot ethanolic solution of the appropriate ligand. The resulting complexes have been characterized by elemental analysis, metal content determination, molar conductance, fast atom bombardment mass spectra, magnetic measurements, thermogravimetric analysis (TGA), IR, and electronic spectral studies. Thermal stability, heat capacity, and activation energy of thermal degradation for these complexes were determined by TGA, differential thermal analysis, and differential scanning calorimetry. Suitable structures are proposed for these complexes.

Synthesis and characterization of Ni(II) complexes of O,N-donor Schiff bases derived from acyl pyrazolone analogues

Two bidentate Schiff bases, 5-methyl-2-p-tolyl-4-(1-p-tolylimino-propyl)-2H-pyrazol-3-ol (L1) and 2-(3-chloro-phenyl)-5-methyl-4-(1-p-tolylimino-propyl)-2H-pyrazol-3-ol (L2), were synthesized by condensation of 4-acyl pyrazolones with p-toluidine in ethanol. These ligands have been characterized by elemental analysis, infrared (IR), 1H NMR, and mass spectra. A single crystal molecular structure of ligand L2 was also solved. Nickel(II) complexes of these ligands with general formula [ML2 · 2H2O] have been prepared by the interaction of aqueous solution of Ni-acetate with ethanolic solution of the appropriate ligand. The complexes were separated, analyzed, and their structures were elucidated on the basis of elemental analysis, Ni(II) determination, IR, UV-Vis, conductance, mass, and TGA-DTA data. Octahedral structure was proposed for the synthesized complexes.

Synthesis and cytotoxicity evaluation of novel acylated starch nanoparticles.

Starch nanoparticles (StNPs) were acylated under ambient conditions to obtain various nanosized derivatives formed stable suspension in water and soluble in organic solvents. The degree of substitution (DS) was determined using (1)H NMR technique. The cytotoxicity potential of the derivatised StNPs was evaluated in mouse embryonic fibroblast (3T3L1) cells and A549 tumor cell line using MTT cell viability assay. Other parameters that determine the oxidative stress viz., reactive oxygen species (ROS) generation, intracellular reduced glutathione (GSH), superoxide generation and acridine orange/ethidium bromide staining were also investigated. The present study led to the conclusion that cytotoxic activity of acylated starch nanoparticles was dependent on their dosage, DS and type of substitution. The non-toxic nature in non-cancerous cells reveals that the nanoparticles (NPs) can be used for cancer therapy and drug delivery. The nanoparticles also offered reasonable binding propensity with CT-DNA.

A comparative study of experimental and theoretical results of conformations of oxovanadium(IV) complexes with 4-acyl pyrazolone ligands using DFT method.

The optimized structures and electronic properties of the oxovanadium(IV) complexes containing 4-acyl pyrazolone ligands were calculated using density functional theory. The total energies of both the complexes were calculated e.g. syn and anti conformation of complex 1 and complex 2 with and without solvent. The calculated total energy for syn conformation was -10.162 keV, while total energy for anti conformation was -10.155 keV. Similarly, the calculated total energy for complex 2 with solvent was obtained -10.793 keV, while total energy for complex 2 without solvent was -10.158 keV. The total energy calculation shows that syn conformation is more stable in complex 1, while complex 2 is more stable in twisted geometry with solvent. In order to investigate the electronic properties of ligands and complexes, quantum chemical parameters, such as the highest occupied molecular orbital energy (HOMO), the lowest unoccupied molecular orbital energy (LUMO), and energy gap were calculated. The theoretically calculated data of the complexes are in good agreement with the data obtained by the single-crystal X-ray diffraction analysis.

(Z)-3-Methyl-1-phenyl-4-[(p-tol­yl)(p-tolyl­amino)­methyl­idene]-1H-pyrazol-5(4H)-one

In the title molecule, C25H23N3O2, the pyrazole ring forms dihedral angles of 28.56 (7), 80.35 (7) and 31.99 (7)° with the phenyl ring, the p-tolyl ring and the p-tolylamino ring, respectively. The N—H group attached to the exocyclic C=C bond is in a syn arrangement with respect to the C=O bond of the pyrazolone group and an intramolecular N—H⋯O hydrogen bond is observed. In the crystal, weak C—H⋯π interactions link molecules along [100].