Synthesis and spectral, antimicrobial, anion sensing, and DNA binding properties of Schiff base podands and their metal complexes

Schiff base podands have been synthesized by reaction of triethylene glycol bis(4-aminophenyl) ether with salicylaldehyde, 5-substituted salicylaldehydes, and 2-hydroxy-1-naphthaldehyde. Manganese(II), iron(II), cobalt(II), nickel(II), and copper(II) complexes have been prepared from the salicylaldehyde-based podand via reaction with MCl2 center dot nH(2)O. The structures of the ligands and complexes have been studied by elemental analysis, FT-IR and UV-visible spectroscopy, H-1 and C-13 NMR, and thermogravimetric analysis. The UV-visible spectral and TG data suggest tetrahedral geometry of the metal complexes. The antimicrobial activities of the ligands and metal complexes have been evaluated as minimum inhibitory concentrations with respect to bacteria and yeast cultures. The interaction of the Schiff base podands with calf thymus DNA has been investigated by UV-visible spectroscopy, and intercalative binding to DNA has been found. The anion recognition ability of all Schiff base podands has been examined by UV-visible spectroscopy. A visually detectable color change has been observed upon addition of fluoride, cyanide, hydroxide, and acetate ions due to formation of 1: 1 H-complexes and/or deprotonation of the receptor. No significant color change has been observed upon addition of other anions such as dihydrogen phosphate, bromide, iodide, thiocyanate, perchlorate, and hydrogen sulfate.