New molecular clips based on diazacrown-n ethers and p-tert-butylcalix[4]arenes molecules? Unusually behavior.

Previously, we demonstrated the complexing abilities of a molecular clip based on diaza-18-crown-6 as a central fragment and p-tert-butylcalix[4]arene molecules which are attached to the diazacrown via an amide groups. This work discloses the comparison of the complexing properties of clips based on diazacrown-n ethers (n = 4, 5, 6). It was found that the molecular clip based on diaza-12-crown-4, demonstrates high selectivity towards rubidium cations among alkali metals, and is able to form binuclear complexes with Mg and Ca cations among alkaline earth metals. The clip based on the unsymmetrical diaza-15-crown-5 ether is an exclusively selective ligand for Cs cations in the alkali metal series, and forms 1:2 (L:M) complexes with cesium and biligand complexes with barium cations. The clip based on diaza-18-crown-6 demonstrates exceptional selectivity for barium cations in the alkaline earth metal series with the formation of 1:1 complexes. The study of the interaction of the obtained clips with transition metal cations indicates that the ligand based on diaza-18-crown-6 is capable of forming predominantly 1:1 complexes with nickel, lead, cadmium, manganese, and cobalt cations (logK>4). In the case of diaza-12-crown-4, the formation of 1:1 complexes with manganese, cadmium, copper and cobalt cations, and biligand mononuclear complexes with nickel, lead and iron cations is observed. A different behavior is characteristic of the clip with diaza-15-crown-5 ether: interaction with nickel, lead, manganese and iron cations leads to the formation of 1:2 (L:M) complexes, but with cadmium, copper and cobalt cations the formation of stable biligand complexes is observed.