Towards new nanoporous biomaterials: self-assembly of sulfopillar[5]arenes with vitamin D₃ into supramolecular polymers

Novel water-soluble, deca-substituted pillar[5]arenes containing thiasulfate and thiacarboxylate fragments were synthesized and characterized. UV-vis, 2D ¹H- ¹H NOESY and DOSY NMR spectroscopy revealed the ability of pillar[5]arenes containing thiasulfate fragments to form an inclusion complex with cholecalciferol (vitamin D ₃) in a 1 : 2 ratio (lg K _ass= 2.2). Using DLS and SEM it was found that upon concentration and/or evaporation of the solvent, the supramolecular polymer (pillar[5]arene/vitamin D ₃(1 : 2)) forms a porous material with an average wall diameter of 53 nm. It was shown that the supramolecular polymer is stable during photolysis by UV radiation (k ₁= 1.7 × 10 ⁻⁵s ⁻¹).