Assembly of a metal–organic framework by sextuple intercatenation of discrete adamantane-like cages

Abstract

Metal-organic frameworks form a unique class of multifunctional hybrid materials and have myriad applications, including gas storage and catalysis. Their structure is usually achieved through the infinite coordination of metal ions and multidentate organic ligands by means of strong covalent bonds. Threaded molecules such as catenanes and rotaxanes have largely been restricted to comprising components of two-dimensional interlocking rings or polygons. There are very few examples of the catenation of polyhedral cages. Although it has been postulated that the infinite extended architecture can be obtained from the polycatenation of a discrete cage based on such threading, this has not been documented to date. Here we describe an infinite three-dimensional metal-organic framework composed of catenated polyhedral cages, in which the framework is achieved by mechanical interlocking of all of the vertices of the cages. The three-dimensional polycatenated framework shows twofold self-interpenetration in its crystal packing. The penetration of polycatenanes creates nanosized voids into which the Keggin polyoxometalate anions are perfectly accommodated as counteranions.

Controllable Coordination Self‐Assembly Based on Flexible Tripodal Ligands: From Finite Metallocages to Infinite Polycatenanes Step by Step

“…The first such polycatenane was reported by Lu and co-workers, who prepared a 3D infinite polycatenane based on adamantane-like metallocages. [64] Dehnen and colleagues then reported the second one. [65] Both polycatenanes are constructed from rigid ligands.…”

An infinite chainmail of M6L6 metallacycles featuring multiple Borromean links

“…41 There are also examples of coordination cages being linked through catenane formation into chain motifs, 28 and into 3D infinite frameworks. 27 In the crystal lattice of 1 the metallacycle chainmail layers stack along the c crystallographic axis. Between the chainmail layers there are face-to-face - stacking interactions between the uncoordinated iso-nicotinoyl groups of adjacent layers at ring centroid separations 3.67 and 3.78 Å, and between some phenyl groups at 3.64 Å, Fig.…”

“…Whole coordination networks may be entangled through interpenetration or polycatenation, [21][22][23] and infinite networks have been reported to form through catenane formation between chemically independent rings 24,25 catenane formation between 1D coordination polymers, 26 or between 3D metallo-cages. 27,28 A Borromean ring or link is composed of three independent rings that are linked together but where no two rings are interlocked into a catenane. They have three principal representations:…”

Cadmium(II)–Triazole Framework as a Luminescent Probe for Ca2+ and Cyano Complexes

“…[1][2][3] Because there are numerous organic and inorganic functional moieties incorporated into the porous materials, MOFs demonstrate remarkable properties for applications in many fields, such as luminescence, gas storage, sensing, magnetics, and catalysis. [4][5][6][7] Nowadays, porous metal-organic frameworks (PMOFs) with dynamic behavior have received considerable interest because these functional coordination frameworks can exhibit guest-induced structural changes of the host lattice. [8] These porous frameworks contain potential or strain energy and undergo dramatic changes in functional properties and structure with the release of energy in response to specific external stimuli.…”