Synthesis, crystal structure, spectroscopic investigations, and computational studies of Ni(II) and Pd(II) complexes with asymmetric tetradentate NOON Schiff base ligand

Synthesis, Characterization, Antimicrobial and Antimalarial Activities of Azines Based Schiff Bases and their Pd(II) Complexes

Herein, we report synthesis, characterization, antimicrobial and antimalarial activities of azines Schiff base ligands (L1 -L4 ) and their palladium (II) complexes (C1 -C4 ) of [Pd(L)(OAc)2 ] type. The azine ligands (L1 -L4 ) were prepared by condensation of carbonyl compounds with hydrazine hydrate and their complexes by the reaction of palladium acetate with L1 -L4 ligands in 1 : 1 molar ratio. The prepared ligands and their complexes were characterized by spectral characterization using 1 H &13 C-NMR, FT-IR and mass spectral studies, which revealed that the ligands coordinates via azomethine nitrogen and heteroatom or aryl carbon with palladium. Moreover, Schiff bases and their palladium (II) complexes have been screened for their antibacterial (S. aureus, B. subtillis, and S. typhi, P. aeruginosa), antifungal (C. albicans, A. niger, and A. clavatus) and antimalarial (P. falciparum) activities. The Schiff base L4 showed good results for antibacterial against S. aureus (MIC, 50 μg/mL) and antimalarial against P. falciparum (IC50 , 0.83 μg/mL). The complex C1 showed best antibacterial activity (MIC, 62.5 μg/mL) against S. typhi and the complex C4 exhibited remarkable antimalarial activity (IC50 , 0.42 μg/mL) among the tested compounds. Thus, azines based ligands and their Pd complexes can be good antimicrobial and antimalarial agents if explored further.

The crystal structure of 2,2′-((1E,1′E)-(naphthalene-2,3 diylbis(azanylylidene)) bis(methanylylidene))bis(4-methylphenol), C26H22N2O2

C26H22N2O2, monoclinic, P21/n (No. 14), a = 6.2362(2) Å, b = 16.3148(6) Å, c = 20.0521(7) Å, β = 94.308(1)°, V = 2034.38(12) Å3, Z = 4, R gt (F) = 0.0439, wR ref (F 2) = 0.1088, T = 173 K.