Gemini guests with spacers of various length drive the self-assembling of supramolecular capsules in water at neutral pH differently

Water-soluble homodimeric capsules resulting from the electrostatic and hydrophobic interactions between a tetracationic calixarene receptor and gemini guests having the negatively charged ends separated by a (-CH2-)(n) (n=2-6) spacer are reported. The formation of the supramolecular capsules occurs through concerted hydrophobic and electrostatic interactions between the charged and aromatic groups of the guests and the host as indicated by H-1 NMR and DOSY NMR data. The different size of the guests may strongly affect the stability of the capsule. The surprising features of these host-guest systems disclose new paths for the design of more efficient anion-templated capsules in highly competitive media such as water.