I will present a successful attempt to incorporate tetraaryl-extended calix[4]pyrrole derivatives into a transition metal−organic framework (calixMOF1) by simply incorporating four terminal carboxylic functional groups at the upper rim of the macrocyclic scaffold. Remarkably, the structures of the metal organic framework and its transition-metal carboxylate clusters (secondary building units, SBU) are governed by the position of the carboxylic substituent in the functionalized meso-aryl units of the linker. Only the tetra-α-meso-arylextended tetracarboxylic calix[4]pyrrole isomer L1, substituted in a single meta-position of their aryl rings, yields a two-dimensional MOF architecture assembled through complex CuII-carboxylate clusters. The metal clusters featured higher nuclearity than the CuII2-(O2CR)4 paddle wheels produced as SBUs during the assembly of the para-substituted counterpart L2 Remarkably, the length of the dialkylformamide used as solvent (DMF or DEF) in the synthesis of the CuII-organic materials derived from L2 played a key role in the structure of the final solid material. The solid-state assembly of discrete CuII paddle wheel-mediated capsular dimers of L2 switched to that of a one-dimensional linear coordination polymer by increasing the solvent’s alkyl chains in a single methylene. Ligand L3, which featured a longer alkyl spacer between the para-substituted calix[4]pyrrole core and the terminal carboxylic groups than L2, self-assembled, exclusively, into discrete capsular coordination dimers also mediated by CuII paddle wheel. Recently, the transfer of the dimeric CuII paddle wheel-mediated capsules from the solid state to solution has been achieved and the preliminary results of binding experiments using these unprecedented assemblies will be discussed.

CuII paddle wheel-mediated dimeric capsules based on tetra-arylextended calix[4]pyrrole ligands

255th National Meeting (2018)

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