Sulfonylcalixaren-Based ortho-Dicarboxylate-Bridged Coordination Containers for Guest Encapsulation and Separation

Four new sulfonylcalix[4]arene-supported coordination containers have been designed and synthesized through the self-assembly of Co(II)/Ni(II), p-tert-butylsulfonylcalix[4]arene, and ortho-dicarboxylate linkers, i.e., 1,2-benzenedicarboxylate or 2,3-naphthalenedicarboxylate. Due to the combined effects of rigid directionality of sulfonylcalixarene-capped tetranuclear subunits and the steric repellent between two ortho carboxylate groups, these synthetic coordination containers suffer from a distorted bonding between the tetranuclear units and dicarboxylate linkers. With the extension of the aromatic system from benzene to naphthalene, significant multiple intermolecular hydrogen bonding and π–π stacking interactions were enhanced, leading to maintaining solid state porosities for small gas molecules. Moreover, they exhibit similar guest binding behaviors toward bulkier dye guests, showing selectively cationic dye adsorption from an aqueous solution of either methylene blue or a methylene blue–eosin Y mixture at the solid–liquid interface. The results not only provide a new designing approach for construction of calixarene-based coordination containers, but also indicate a promising opportunity of these new materials for the application of guest recognition and separation.