Pathway-Dependent Post-assembly Modification of an Anthracene-Edged M~Ⅱ_4L_6 Tetrahedron

摘要

Fe~Ⅱ_4L_6 tetrahedral cage 1 undergoes post-assembly modification (PAM) via a Diels-Alder cydo-addition of the anthracene panels of the cage with tetracyanoethylene (TCNE). The modified cage 2 possesses an enclosed cavity suitable for encapsulation of the fullerene C_(60), whereas original cage 1 forms a unique covalent adduct through a Diels-Alder cydoaddition of three of its anthracene ligands with C_(60). This adduct undergoes further PAM via reaction of the remaining three ligands with TCNE, enabling the isolation of two distinct products depending on the order of addition of C_(60) and TCNE. Modified cage 2 was also able to bind an anionic guest, [Co(C_2B_9H_(11)))2]~-, which was not encapsulated by the original cage, demonstrating the potential of PAM for tuning-the binding properties of supramolecular hosts.