Synthesis and anion recognition studies of new oligomethylene bis(nitrophenylureylbenzamide) receptors.

A new series of oligomethylene bis(nitrophenylureylbenzamide) receptors were synthesized varying the relative position of the urea and amide groups (4 and 8) and the length of the oligomethylene chain (C to C). An anion recognition study was performed with TBAX salts (X = AcO, BzO, F, HPO , and HPO ) by UV-vis and H NMR. The flexibility of these receptors allows a cooperative effect of both ureylbenzamide units in the receptors.