p-tert-Butylthiacalix[4]arenes functionalized by N-(4’-nitrophenyl)acetamide and N,N-diethylacetamide fragments: synthesis and binding of anionic guests

New p-tert-butylthiacalix[4]arenes, which are mono-, 1,2-di- and tetrasubstituted at the lower rim containing N-(4’-nitrophenyl)acetamide and N,N-diethylacetamide groups in cone and partial cone conformations have been synthesized. Their complexation ability towards a number of tetrabutylammonium salts n-Bu(4)NX (X = F(−), Cl(−), Br(−), I(−), CH(3)CO(2)(−), H(2)PO(4)(−), NO(3)(−)) was studied by UV spectroscopy. The effective receptor for the anions studied as well as selective receptors for F(−), CH(3)CO(2)(−) and H(2)PO(4)(−) ions, which based on the synthesized thiacalix[4]arenes, have been obtained. It was shown that p-tert-butylthiacalix[4]arene tetrasubstituted at the lower rim by N-(4’-nitrophenyl)acetamide moieties bonded to the anions studied with association constants within the range of 3.55 × 10(3)–7.94 × 10(5) M(−1). Besides, the binding selectivity for F(−), Cl(−), CH(3)CO(2)(−), and H(2)PO(4)(−) anions against other anions was in the range of 4.1–223.9. Substituting one or two fragments in the macrocycle with N,N-diethylacetamide groups significantly reduces the complexation ability of the receptor. In contrast to the 1,3-disubstituted macrocycle containing two N-(4’-nitrophenyl)acetamide moieties, the 1,2-disubstituted thiacalix[4]arene, which contains only one such fragment and a N,N-diethylacetamide moiety, selectively binds F(−) anions.