Synthesis of novel coordination compounds of 5-aryl-4,5-dihydro-3-(2-hydroxyphenyl)pyrazoles as potential fungicides

Base-catalyzed condensation of 2-hydroxyacetophenone with araldehydes gave 3-aryl-1-(2-hydroxyphenyl)prop-2-en-1-ones with E-configuration, which on c yclization with hydrazine hydrate afforded the title ligands, 5-aryl-4,5-di hydro-3-(2-hydroxyphenyl)pyrazoles (ADHP; Ar = Ph, 4-CH3O-C6H4-, 2-furyl, 2 -thienyl; HL1 - HL4). Reaction of HL1 - HL4 with divalent metal ions, Mn2+, Co2+, Ni2+, Cu2+, and Zn2+, afforded novel coordination compounds of the t ype [ML2(H2O)(2)] (M = Mn, Co, Ni, Cu, Zn) which were characterized by elem ental analyses, molecular weight determinations, molar conductances, magnet ic moments, electronic and infrared spectral data. The ligands behaved as b identates, coordinating through the phenolic oxygen after deprotonation and N-2 of the pyrazole ring. The ligands and their complexes were evaluated f or growth-inhibiting activity against phytopathogenic fungi namely, Alterna ria alternata, Colletotrichum falcatum, Fusarium oxysporum and Rhizoctonia bataticola. Some of the ligands and their metal complexes exhibited promisi ng activity.