Solvent-free synthesis of novel chiral unsymmetrical urea molecular tweezers under microwave irradiation

Seven novel chiral unsymmetrical urea molecular tweezers based on 1, 3-phenoxyacetic acid have been designed and synthesised using solid K2CO3 as supporter in the solvent-free conditions under microwave irradiation. This method is simple, fast, efficient and eco-friendly. The structures of target compounds were characterised by IR, 1H NMR, MS spectra and elemental analyses and their molecular recognition properties were investigated by UV-Vis spectral titration. The preliminary results indicated that these molecular tweezers possess good selectivity for D/L amino acid methyl esters and some anions.