Lower rim 1,3-di-amide-derivative of calix[4]arene possessing bis-{N-(2,2′-dipyridylamide)} pendants: a dual fluorescence sensor for Zn2+ and Ni2+

Single crystal XRD structure of the lower rim 1,3-di-amide-derivative of calix[4]arene possessing bis-{N-(2,2′-dipyridylamide)} pendants (L) exhibit two distinct binding cores, viz., N4 and O6. L was found to be selective for Zn2+ by switch-on and for Ni2+ by switch-off fluorescence by forming 1:1 complexes. The binding and the composition of the complex formed have been addressed based on steady state and time-resolved fluorescence spectroscopy in addition to the absorption and ESI MS. As L can detect Zn2+ and Ni2+ to a concentration as low as 142 and 203 ppb, respectively, L can be a very sensitive molecular probe for these ions. The coordination details of the metal ion-bound complexes have been addressed based on ab initio calculations showing that the stabilization energies are commensurate with the coordination formed.

Single crystal XRD structure of the lower rim 1,3-di-amide-derivative of calix[4]arene possessing bis-{N-(2,2′-dipyridylamide)} pendants (L) exhibits two distinct binding cores, viz., N4 and O6. L was found to be selective to Zn2+ by switch-on and to Ni2+ by switch-off fluorescence by forming 1:1 complexes, where the lowest Zn2+ and Ni2+ concentration detection limits are 142 and 203 ppb, respectively. The coordination aspects of these complexes have been addressed based on computational calculations.Figure optionsDownload as PowerPoint slide