Synthesis, structural characterization, and molecular docking studies of bioactive bismuth(III) complexes with substituted hydrazones

Abstract

Eight new bismuth(III) complexes (1-8) of substituted hydrazones having general formula; [Bi(RCONHNCHC5H4N)Clx] and [Bi(RCONHNCHC9H6N)Clx], where R = C10H7O (1, and 8), C4H3S (2), C6H5O (3, and 6), C7H7(4), C5H4N (5, and 7), x = 2 or 3 have been prepared. The substituted hydrazones (I1-I8) were synthesized by reacting the stoichiometric amounts of the respective hydrazides such as p-toluic hydrazide, 4-hydroxybenzhydrazide, thiophene-2-carboxylic acid hydrazide, 3-hydroxy-2-naphthoic acid hydrazide, Isonicotic acid hydrazide and appropriate aromatic aldehydes like pridine-2-carboxaldehyde and quinoline-2-carboxyaldehyde. These hydrazones (ligands),then complexed to Bi(III) species to yield the target compounds. They were characterized by FTIR, and NMR spectroscopy to find out an explicit evidence about their structural motifs. The X-ray data for (1 & I6) further validate the chemical structures of the synthesized compounds. The molecular geometry for (1) is predominately distorted pentagonal bipyramidal where hepta-coordinated Bi(III) center is attached to the nitrogens of pyridine and of azomethine moieties along with the carbonyl oxygen, two chloro and two oxygens of the (two) DMSO molecules. The bond lengths for Bi(1)-O(1), Bi(1)-N(1) and Bi(1)-N(2) are 2.323(5), 2.539(6), 2.390(5) oA respectively indicating Bi(1)-O(1) as the strongest linkage to the metal center. The H-bonding, present in (1), contributed an extra stability to the structure. The synthesized compounds were initially screened for their possible antimicrobial, alpha-amylase, and protein kinase inhibition, some (1,2,6,8) exhibit significant activity. The experimental results are further endorsed by molecular docking studies against helicobacter pylori urease (1E9Y), epidermal growth factor receptor tyrosine kinase (1M17) and human pancreatic alpha amylase (5U3A) inhibition activity. The significant ligand-receptor interactions, observed at the binding pocket of the selected drug targets, further revealed the enzyme inhibition potential of the compounds and highlighting their possible roles as therapeutic agents in future drug discovery processes.