Highly selective and sensitive receptor for Fe3+ probing.

A new fluorescent receptor 1,1'-(4-methylbenzene-1,3-diyl)bis[3-(2-sulfanylphenyl)urea] (1) has been designed and synthesized. The receptor showed excellent selectivity for Fe(3+) in DMSO/H2O (8:2, v/v) solvent system over other commonly coexistent metal ions. The binding constant (Ka) of receptor with Fe(3+) was calculated to be 11,250 M(-1), 12,970 M(-1) and 12,970 M(-1) using Benesi-Hildebrand, Scatchard and Connor plot, respectively. The experimental results have been further supported by the detailed DFT calculations.