Strapped-calix[4] pyrroles bearing acridine moiety

Calix[4] pyrrole bearing 5-aryl acridine-derived straps on one side of the tetrapyrrolic core have been synthesized and characterized. The solution state binding studies of the synthesized hosts were investigated by proton NMR spectroscopy and Isothermal Titration Calorimetry (ITC) in acetonitrile. The system displayed enhanced affinities for chloride and bromide anion with high selectivity and the inner aryl C-H of the strap served as a C-H hydrogen bond donor site. The fluorescence measurement indicated that the incorporated acridine moiety has minimal interaction with the anion binding event.