Synthesis and anion recognition of neutral receptors based on multiamide calix[4]arene

Two multiamide calix[4]arenes (5, 6) were synthesized and characterized by NMR, MS and elemental analysis. The binding properties of receptors with some anions (π-O2NPhOPO32−, π-O2NPhO−, H2PO4−, Ac−, Cl−, Br− and I−) were studied by UV-Vis spectra. The results indicate that the tetraamide calix[4]arenes (5, 6) have a good selectivity to the anions containing aromatic ring (π-O2NPhOPO32−, π-O2NPhO−). The 1 : 1 complexes between host and guest were formed through multiple hydrogen bonding and π-π interactions. The hosts 5 and 6 also show a definite binding ability for the anions (H2PO4−, Ac−, Cl−) that have no ultraviolet absorption, which provides a simple method of spectrum detection for these anions.