Montmorillonite K-10 Supported 11-molybdo-1-vanadophosphoric Acid (H4PMo11V1O40/K-10) Catalysts for Environmentally Benign Synthesis of 2H-indazolo[2,1-b]phthalazine-triones Under Solvent-free Condition

A series of 11-molybdo-1-vanadophosphoric acid supported on montmorillonite K-10 catalysts were prepared and characterized by FT-IR spectroscopy, thermal analysis, XRD, BET and SEM analysis techniques. Characterization data reveals the chemical immobilization of H4PMo11V1O40 catalyst on the montmorillonite K-10 support. The catalytic performance of synthesized catalysts was investigated for the synthesis of 2H-indazolo[2,1-b]phthalazine-1,6,11(13H)-trione derivatives by one-pot three-component reaction of phthalhydrazide, dimedone and aromatic aldehydes under solvent-free conditions. Among different catalysts, 20% H4PMo11V1O40 supported on to montmorillonite K-10 showed the highest catalytic activity. Effect of reaction parameters such as catalyst loading, temperature and the nature of substituents on the aromatic ring of aldehydes were also evaluated. The protocol developed using H4PMo11V1O40/K-10 has several distinct advantages such as operational simplicity, short reaction time, high yield, reusable catalyst and preclusion of toxic solvent. DOI: http://dx.doi.org/10.17807/orbital.v9i4.87

A Simple and Green Protocol for the Synthesis of 3,4-dihydropyrimidin-2(1H)-ones Using 11-Molybdo-1-vanado phosphoric Acid as a Catalyst Under Ultrasound Irradiation

A one-pot three-component reaction of ethyl acetoacetate, aldehydes and urea has efficiently been carried out in the presence of 11-molybdo-1-vanadophosphoric acid in ethanol at room temperature under ultrasound irradiation to form the corresponding 3,4-dihydropyrimidin 2(1H)-ones in high yields. The 11-molybdo-1-vanadophosphoric acid (H4PMo11V1O40) was prepared and characterized by FT-IR spectroscopy, TG-DTA analysis and XRD analysis techniques. The presence of Keggin structure and incorporation of vanadium into the Keggin structure of synthesized H4PMo11V1O40 catalyst was confirmed by FT-IR and powder XRD analysis techniques. TG-DTA analysis results indicated that H4PMo11V1O40 catalyst was thermally stable up to the temperature 434 °C. The present catalytic system is recyclable and can be reused without greater loss of reactivity. DOI: http://dx.doi.org/10.17807/orbital.v11i5.1423   </p

Montmorillonite K-10 Supported 11-molybdo-1-vanadophosphoric Acid (H4PMo11V1O40/K-10) Catalysts for Environmentally Benign Synthesis of 2H-indazolo[2,1-b]phthalazine-triones Under Solvent-free Condition

A series of 11-molybdo-1-vanadophosphoric acid supported on montmorillonite K-10 catalysts were prepared and characterized by FT-IR spectroscopy, thermal analysis, XRD, BET and SEM analysis techniques. Characterization data reveals the chemical immobilization of H4PMo11V1O40 catalyst on the montmorillonite K-10 support. The catalytic performance of synthesized catalysts was investigated for the synthesis of 2H-indazolo[2,1-b]phthalazine-1,6,11(13H)-trione derivatives by one-pot three-component reaction of phthalhydrazide, dimedone and aromatic aldehydes under solvent-free conditions. Among different catalysts, 20% H4PMo11V1O40 supported on to montmorillonite K-10 showed the highest catalytic activity. Effect of reaction parameters such as catalyst loading, temperature and the nature of substituents on the aromatic ring of aldehydes were also evaluated. The protocol developed using H4PMo11V1O40/K-10 has several distinct advantages such as operational simplicity, short reaction time, high yield, reusable catalyst and preclusion of toxic solvent. DOI: http://dx.doi.org/10.17807/orbital.v9i4.873 </p

Synthesis, spectral, thermal, potentiometric and antimicrobial studies of transition metal complexes of tridentate ligand

A series of metal complexes of Cu(II), Ni(II), Co(II), Fe(III) and Mn(II) have been synthesized with newly synthesized biologically active tridentate ligand. The ligand was synthesized by condensation of dehydroacetic acid (3-acetyl-6-methyl-(2H) pyran-2,4(3H)-dione or DHA), o-phenylene diamine and fluoro benzaldehyde and characterized by elemental analysis, molar conductivity, magnetic susceptibility, thermal analysis, X-ray diffraction, IR, 1H-NMR, UV–Vis spectroscopy and mass spectra. From the analytical data, the stoichiometry of the complexes was found to be 1:2 (metal:ligand) with octahedral geometry. The molar conductance values suggest the non-electrolyte nature of metal complexes. The IR spectral data suggest that the ligand behaves as a dibasic tridentate ligand with ONN donor atoms sequence towards central metal ion. Thermal behaviour (TG/DTA) and kinetic parameters calculated by the Coats–Redfern and Horowitz–Metzger method suggest more ordered activated state in complex formation. To investigate the relationship between stability constants of metal complexes and antimicrobial activity, the dissociation constants of Schiff bases and stability constants of their binary metal complexes have been determined potentiometrically in THF–water (60:40%) solution at 25 ± 1 °C and at 0.1 M NaClO4 ionic strength. The potentiometric study suggests 1:1 and 1:2 complexation. Antibacterial and antifungal activities in vitro were performed against Staphylococcus aureus, Escherichia coli and Aspergillus niger, Trichoderma, respectively. The stability constants of the metal complexes were calculated by the Irving–Rosotti method. A relation between the stability constant and antimicrobial activity of complexes has been discussed. It is observed that the activity enhances upon complexation and the order of antifungal activity is in accordance with stability order of metal ions