Guest inducing p-sulfonatocalix[4]arene into three-dimensional capsule architecture and a mixed A–B double layer framework

Abstract

The reactions of sodium p-sulfonatocalix[4]arene (Na5L) and terbium/europium(III) chloride in the presence of pyrazine-N,N′-dioxide (PNNO) in aqueous solutions gave the crystalline complexes 1 and 2. Both structures contain molecular capsules of p-sulfonatocalix[4]arene with PNNO as guest molecules in the cavity of the calix[4]arenes. The molecular capsules are connected through sodium and terbium (or europium) centers forming a three-dimensional framework. The yellow crystals from an aqueous solution containing Na5L and lanthanum(III) chloride reacted with PNNO in aqueous solutions, giving crystals of complex 3. Compound 3 is a special mixed A–B type layer framework of p-sulfonatocalix[4]arene. The structure of compound 3 is made up of two types of bilayered p-sulfonatocalix[4]arene with opposite charges. The two types of layers (in presence or absence of sodium centers) alternate with each other forming a mixed A–B type double bi-layer framework which is uncommon in the layer structure of p-sulfonatocalix[4]arene.