Selective Cation Recognition by p-Tetranitrocalix[4]arene

The present study explores the copper selective complexation character of 5,11,17,23-tetranitro-25,26,27,28-tetrahydroxycalix[4]arene (p-TNC4) among a series of different alkali, alkaline earth and transition metal ions, i.e. Li+, Na+, K+,Cs+ Mg2+, Ba2+, Hg2+, Cd2+, Pb2+, Co2+ Ni2+ and Zn2+ using absorption spectroscopic technique. p-TNC4 shows pronounced discriminative specificity towards Cu2+ even the interference study of other co-existing ions also proved this selectivity. Furthermore, the solvatochromic effect, effect of acid (acetic acid), alkali (piperidine) on spectra, response time measurement and the stability of p-TNC4-Cu2+ complex in MeCN has also been investigated. The stoichiometric analysis (i.e. Jobs plot) reveals that p-TNC4 forms 1:1 host-guest complex with Cu2+.