Graphene Oxide-terpyridine Conjugate: A Highly Selective Colorimetric and Sensitive Fluorescence Nano-chemosensor for Fe²⁺ in Aqueous Media

Abstract

A graphene oxide-terpyridine conjugate (GOTC) based colorimetric and fluorescent nano-chemosensor was synthesized. It showed high selectivity and sensitivity for Fe²⁺ and Fe³⁺ ions in neutral aqueous solution over other metal ions such as Li+, Na+, Ba²⁺, Ca²⁺, Al³⁺, Cd²⁺, Co²⁺, Cu²⁺, Hg²⁺, Mn²⁺, Ni²⁺, Pb²⁺, Zn²⁺, Cr³⁺ and Ag+. In absorption spectra, upon addition of Fe²⁺ or Fe³⁺, the sensor displ<span id="transmark" style="display: none; width: 0px; height: 0px;"></span>ayed a peak at 568 nm, by changing the color of the solution from light pink for GOTC to light magenta and deep magenta for Fe3+ and Fe²⁺, respectively. Also, the fluorescence studies revealed that, Fe²⁺, Fe³⁺ and Co²⁺ quench the emission of GOTC at 473 nm, while other metal ions do not quench the fluorescence of GOTC in solution. Colorimetric and fluorescence techniques could be used for detection of Fe²⁺ ion concentration at least about 6-10 μM in water solution. The sensing on test paper was also investigated for the naked-eye detection of Fe²⁺.