Molecular binding behavior of water-soluble calix[4]arenes with asymmetric 4,4'-bipyridinium guests in aqueous solution: regioselective recognition or not?

作者：Wang, Kui^*; Cui, Jian-Hua; Xing, Si-Yang^*; Dou, Hong-Xi

来源：Organic and Biomolecular Chemistry, 2016, 14(46): 10804-10811.

DOI：10.1039/c6ob02105k

• SULFONATED CALIXARENES
• P-SULFONATOCALIXARENE
• DYNAMICS SIMULATIONS
• ENZYME ASSAYS
• LIFE-SPAN
• COMPLEXES
• CATIONS
• POLYMER
• THERMODYNAMICS
• CYCLODEXTRIN

The molecular binding behavior of water-soluble calix[4] arenes (p-sulfonatocalix[4] arene (SC4A) and p-sulfonatothiacalix[4] arene (STC4A)) with two asymmetric 4,4'-bipyridinium guests (N-methyl-N'-adamantane carbomethyl-4,4'-bipyridinium dibromide (MVAd(2+)) and N-methyl-N'-(naphthalen-2-ylmethyl)-4,4'-bipyridinium bromide iodide (MVNp2+)) was systematically studied using NMR spectroscopy and microcalorimetry in a neutral aqueous solution. Either the methyl group or the adamantane moiety in MVAd(2+) could enter into the SC4A and STC4A cavities, without regioselectivity. The STC4A cavity can also accommodate MVNp2+, either through incorporation of the methyl group or the naphthalene moiety, without regioselectivity. However, we were surprised to find that MVNp2+ could only be included within the SC4A cavity through incorporation of the methyl group, with regioselectivity, which is rare for a flexible host. Furthermore, both SC4A and STC4A can form stable inclusion complexes with the two investigated asymmetric 4,4'-bipyridinium guests, driven by very favorable enthalpy changes, and the thermodynamic origins of the host selectivities for MVAd(2+) and MVNp2+ can be well explained through their binding modes. The finding of this novel regioselective recognition is promising for potential applications in the development of more sophisticated biomimetic materials.

• 出版日期2016
• 单位天津师范大学