Parsimonious Topology Based on Frank-Kasper Polyhedra in Metal–Organic Frameworks

A new topology previously unknown in metal–organic
frameworks
(MOFs) provides an important clue to uncovering a new series of polyhedral
MOFs. We report a novel MOF crystallized in a parsimonious mep topology based on Frank–Kasper (FK) polyhedra. The distribution
of angles in a tetrahedral arrangement (T-O-T) is crucial for the
formation of FK polyhedra in mep topology. This finding
led us to investigate the T-O-T angle distribution in related zeolites
and zeolitic imidazolate frameworks (ZIFs). Unlike zeolites, it is
extremely difficult to achieve high T-O-T angles in ZIFs, which prevents
the formation of some FK topologies. Density functional theory (DFT)
total energy calculations support a correlation between T-O-T angles
and the feasibility of new tetrahedron-based FK frameworks. This result
may lead to innovative ways of accessing new cellular topologies by
simple chemical tweaking of T-O-T angles.