Controlling the conformation and interplay of p-sulfonatocalix[6]arene as lanthanide crown ether complexes |
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Authors: | Dalgarno Scott J Hardie Michaele J Makha Mohamed Raston Colin L |
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Institution: | Department of Chemistry, Univeristy of Leeds, UK. |
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Abstract: | Control over the conformational flexibility of p-sulfonatocalix6]arene in the solid state is possible in the presence of varied stoichiometric amounts of 18]crown-6 and selected lanthanide(III) chlorides. Complexes 1 and 2 have the calixarene in the elusive up-up double cone conformation, whilst complex 3 has the calixarene in the centrosymmetric up-down double partial cone conformation, whereby it acts as a divergent receptor. Complex 1 has a double molecular capsule arrangement which is composed of two p-sulfonatocalix6]arenes shrouding two 18]crown-6 molecules, also with both coordinated and homoleptic aquated lanthanide ions around the hydrophilic sulfonate rims of the calixarenes. Complex 2 has a ferris wheel arrangement with one lanthanide metal centre coordinated to a sulfonate group and another coordinated to the crown ether whilst tethered to a sulfonate group of the calixarene. Complex 3 forms from a solution with large excess of 18]crown-6, and possesses a crown ether molecule in each of the partial cones and has homoleptic aquated lanthanide ions involved in a complicated hydrogen-bonding regime within the extended structure. |
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Keywords: | calixarenes crown compounds host–guest systems self‐assembly supramolecular chemistry |
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