Synthetic and Biocidal Studies on Novel Coordination Compounds of Substituted 4,5-Dihydropyrazoles

Abstract

Reaction of 1-acetyl-3-aryl-5-(2-thienyl)-4,5-dihydropyrazoles (AATP; Ar=2-OHC₆,H₄, 1-OHC₁₀H₆ and 2-OHC₁₀H₆) with divalent metal ions in ethanolic solution afforded novel complexes of the type ML₂. The structures of the isolated complexes have been elucidated on the basis of elemental analysis, molecular weight determination, molar conductance, magnetic moment and spectroscopic data. The IR spectra indicated that the ligands coordinated in a tridentate manner via OH (phenolic) after deprotonation, azomethine nitrogen (C=N), and carbonyl oxygen (C=O) of acetyl group attached to the nitrogen of the pyrazole ring. The ligands exhibited powerful in vitro microbiocidal activity against phytopathogenic fungi viz., Alternaria alternate, Colletotrichum capsicum, Fusarium oxysporum, Rhizoctonia solani and bacteria viz., gram positive Bacillus subtilis and gram negative Escherichia coli which was significantly enhanced on coordination with the metal ions. The trend of