A C₆₀-Templated Tetrameric Porphyrin Barrel Complex via Zinc-Mediated Self-Assembly Utilizing Labile Capping Ligands

Abstract

Coordination-driven self-assembly utilizing labile capping ligands has been exploited as a novel strategy for metallo-cage containers. Herein, we report a tetrameric porphyrin barrel complex [C60⊂Zn814(H2O)4(OTs)12](OTs)4 (2) (OTs = p-CH3C6H4SO3) formed from a tetrakis(bipyridyl)porphyrin ligand 1, Zn(OTs)2, and a template guest, C60 fullerene. The tetrameric-barrel 2 contains two kinds of bis(bpy) Zn(II) centers coordinated by TsO(-) anions which serve as labile capping ligands in the formation of the finite structure of 2.

Reversible C60 Ejection from a Metallocage through the Redox‐Dependent Binding of a Competitive Guest

“…In particular, the development of systems able to encapsulate and liberate fullerenes has emerged as an attractive method for the purification of this important class of molecules . The development of highly diverse coordination‐based nanoreceptors exhibiting high binding affinity and selectivity for different‐size fullerenes (i.e., trigonal, tetrahedral and cubic cages, barrel, capsule) has been described in the last decade. On the other hand, several strategies have been applied to liberate the sequestered fullerene from supramolecular receptors.…”

Sponge-like molecular cage for purification of fullerenes

“…Host platforms containing extended p-systems have been designed because of their affinity towards the sphere-like unsaturated structure of fullerenes. In this line, several covalent or supramolecular approaches pursued include: (a) macrocyclic arene-based receptors [18][19][20][21][22][23][24] , (b) macrocyclic structures containing aromatic heterocycles [25][26][27][28] , (c) p-extended TTF receptors [29][30][31][32][33] and (d) macrocyclic or jawlike structures containing porphyrin moieties 17,[34][35][36][37][38][39][40][41][42][43][44][45] . Interestingly, Fujita and co-workers reported the use of the empty channels of a metal-organic framework (MOF) for encapsulating fullerenes upon soaking MOF crystals in fullerene-containing toluene.…”

Guest‐Induced Transformation of a Porphyrin‐Edged FeII4L6 Capsule into a CuIFeII2L4 Fullerene Receptor

“…Models of C 70 ⊂ 3 (Figure S36) reveal no features that would be indicative of strain, with the porphyrins bowed outwards in a similar fashion to that observed in the crystal structure of 2 (Figure 1) to create the internal cavity necessary to house C 70 . Fullerene encapsulation thus appears to provide enough of an energetic driving force, in the form of more favorable π interactions between the porphyrin units of the host and the guest,5c,f, 15 to drive the transformation of 2 into 3 . Geometric factors and the strength of guest binding thus tip the balance against the tendency for iron(II) to maintain coordinative saturation 16.…”