Synthesis, X-ray structure, Hirshfeld analysis and antidiabetic assessment of a novel μ-oxalato Cu(II)-pyrazolone complex

An unexpected dinuclear [(Cu(PP)(H2O))2-mu-ox]center dot 3H2O complex; CuPPO, comprising a bridged oxalate anion (ox2-) and 5-methyl-4-nitro-3-oxo-2-(pyridin-2-yl)-2,3-dihydropyrazol-1-ide (PP) as ligands was synthesized by reaction of 4-(2-(3-methyl-5-oxo-1-(pyridin-2-yl)- 1,5-dihydro-4H-pyrazol-4-ylidene)hydrazinyl) benzenesulfonamide (HPPS) and Cu(NO3)2 center dot 3H2O in presence of nitric acid and ethanol as solvent. An unexpected oxidation of ethanol to oxalate anion in addition to hydrolysis of HPPS with subsequent nitration occurred leading to formation of the PP ligand which acting as a bidentate NN-chelate. The new complex is characterized by elemental analysis, FTIR analysis, and single crystal X-ray diffraction. In this dinuclear complex, there are two crystallographically independent penta-coordinated Cu(II) centers with square pyramidal coordination geometry. The variety of intermolecular interactions affecting the molecular packing of the Cu(II) complex were decomposed by Hirshfeld analysis. The most significant interactions are O center dot center dot center dot H (33.4 %) and C center dot center dot center dot H (10.7 %). In addition, enrichment ratios greater than 1 for O center dot center dot center dot H, O center dot center dot center dot N, O center dot center dot center dot C, H center dot center dot center dot H, N center dot center dot center dot C, and C center dot center dot center dot C revealed high predisposition of each atom pair to interact. CuPPO was evaluated for its in vitro anti-diabetic activity against alpha-glucosidase, alpha-amylase and glucose uptake and the results are compared with acarbose and berberine as reference antidiabetic drugs. CuPPO showed excellent inhibitory potential against alpha-glucosidase with IC50 values 6.52+ 0.33 mu M. Also, CuPPO showed higher glucose uptake compared to berberine with EC50 values of 19.03+0.12 mu M.