Abstract
A novel colorimetric cation sensor based on polyethyleneiminehydrochloride (PEI.HCl) as Schiff base was synthesized. The molecular structure of the PEI.HCl-Schiff base was characterized via FT-IR, H-1 NMR, C-13 NMR, LC-MS and UV-vis spectroscopic methods The chromogenic sensing ability of PEI.HCl-Schiff base was investigated with colorimetric and UV-vis spectroscopy. The designed sensor exhibited highly selective recognition for Fe2+, Co2+, Cu2+, Cr3+, and Fe3+ amongst a wide range of metal ions tested in water. In the presence of these cations, the sensor underwent a dramatic colour change from yellow to green, while the presence of other metal cations such as Mn2+, Ni2+, Zn2+, Cd2+, Hg2+ and Pb2+ produced no effect on the colour. The absorption spectral changes were observed upon the addition of Fe2+, Co2+, Cu2+, Cr3+, and Fe3+ with impressive naked eye detectable colour change from yellow to dark-gray, light-brown, green, light-green and brown, respectively. The most discernable colour change in the PEI.HCl-Schiff base was caused by Fe2+, Co2+, Cu2+, Cr3+, and Fe3+ suggesting the selective detection of these metal cations. Surprisingly, PEI.HCl-Schiff base behaves as highly selective chemical sensor for the oxidation of Fe2+ to Fe3+ cations. Moreover, the antimicrobial activity of PEI.HCl-Schiff base was tested for its minimum inhibitory concentration (MIC), and the interaction with calf thymus DNA (CT-DNA) was investigated using UV-vis spectroscopy. DNA cleavage study showed that PEI.HCl-Schiff base can successfully cleave DNA without any external agents. (C) 2017 Elsevier B.V. All rights reserved.
