Self-Assembly of a Binodal Metal-Organic Framework Exhibiting a Demi-Regular Lattice
Designing metal-organic frameworks with new topologies is a long-standing quest be-cause new topologies often accompany new properties and functions. Here we report that 1,3,5-tris[4-(pyridin-4-yl)phenyl]benzen molecules coordinate with Cu atoms to form a two-dimensional framework in which Cu adatoms form a nanometer-scale demi-regular lattice. The lattice is articulated by perfectly-arranged twofold and threefold pyridyl-Cu coordination motifs at a ratio of 1:6 and features local dodecagonal symmetry. This structure is thermodynamically robust and emerges solely when the molecular density is at a critical value. In comparison, we present three framework structures that comprise of semi-regular and regular lattices of Cu atoms self-assembled out of 1,3,5-tris[4-(pyridin-4-yl)phenyl]benzene and trispyridylbenzene molecules. Thus a family of regular, semi-regular and demi-regular lattices can be achieved by Cu-pyridyl coordination.