Molecular Binding Behaviors of Sulfonated Calixarenes with Phenanthroline-diium in Aqueous Solution and Solid State: Cavity Size Governing Capsule Formation

摘要

The molecular binding behaviors of psulfonatocalix[4]arene (SC4A), p-sulfonatocalix[5]arene (SC5A), and p-sulfonatothiacalix[4]arene (STC4A) with 5,6-dihydropyrazion[1,2,3,4-lmn][1,10]phenanthroline-4,7-diium (DP~(2+)) were systematically investigated by crystallography, NMR spectroscopy, and microcalorimetry at pH 1?2. The obtained results showed that, in both aqueous solution and the solid state, DP~(2+) was immersed into the cavity of the sulfonated calixarene host in a slantwise degree with the aromatic moiety being included first. The different slantwise degree of the guest in the host cavity determined whether the host? guest capsule could be formed in the solid state. Furthermore, all three sulfonated calixarene hosts showed high affinities with DP~(2+) in the magnitude of 10~5?10~6 M~(?1) in aqueous solution, and the binding modes for host?guest complexation were explained from a thermodynamic viewpoint.