4-tert-butylcalix[4]arene having nitrile pendant groups as Hg2+ selective receptors

We synthesized a series of 4-tert-butylcalix[4]arene nitriles (5–7) by the reaction of 4-tert-butylcalix[4]arene (1) with 4′-(6-bromohexyloxy)biphenyl-4-carbonitrile (2), 4′-(10-bromode-cyloxy)biphenyl-4-carbonitrile (3), and 4′-(12-bromododecyloxy)biphenyl-4-carbonitrile (4) and characterized their structures, respectively. The extraction abilities of newly synthesized 5–7 toward some selected heavy metal cations, such as Co2+, Cu2+, Ni2+, Zn2+, Cd2+, and Hg2+, were first evaluated and compared by the solvent extraction method. The extraction results revealed that 5–7 were efficient and selective cation receptors for Hg2+ over-selected cations. On the other hand, the complexation behavior of Hg2+ with 5–7 was also investigated by using NMR, UV–vis, and IR spectroscopic methods.