Biological active novel 2,4-dinitro phenyl hydrazones as the colorimetric sensors for selective detection of acetate ion

• Novel multidentate hydrazones (L1 and L2) as anion sensors were synthesized and characterized.
• Selective colorimetric determination of acetate ion.
• UV–vis and NMR studies were performed.
• Antimicrobial activity of L1 and L2 were tested.

Novel hydrazones such as 1-(2,4-dinitrophenyl)-2-((3-methylthiophen-2-yl)methylene)hydrazine (L1) and 1-(6-(2-(2,4-dinitrophenyl)hydrazono)ethyl)pyridine-2-yl)ethanone (L2) have been synthesized and explored as colorimetric sensors. Systematic studies of ionophores (L1 and L2) with acetate ion in DMSO revealed that they involved in H-bonding and proton transfer with acetate ion. Due to these interactions change in visible region of spectrum was observed and colour of both the ionophores changed from yellow (L1) and orange yellow (L2) to magenta. Further ligand–acetae ion interactions were studied with the help of 1H NMR titration in DMSO and found that binding is the combined function of hydrogen bonding, electrostatic interactions and structure of binding site. Antimicrobial activities of ionophores (L1 and L2) were examined and tested against fungi: Rhizoctonia solani and Bipolaris oryzae using agar well diffusion method. Both ligands L1 and L2 were found to be exhibit antifungal activity against these strains. Antibacterial activity of L1 and L2 was also studied against Gram positive bacteria: Staphylococcus aureus, Bacillus brevis and Gram negative bacteria: Escherichia coli, Pycnoclavella diminuta using disc diffusion method and it was cleared that ligands were not inhibiting the growth of these strains even at higher concentration of both the ligands.

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