Anisotropic reticular chemistry

Reticular chemistry has been focused on making simple structures in which a few kinds of components are linked to make crystals such as metal–organic frameworks (MOFs). While this chemistry has grown into a large field, a more extensive area with fascinating directions is emerging through the introduction of multiplicity and variation into the components of MOFs. When the MOF backbone is composed of more than two kinds of components, the resulting backbone multiplicity is regular repeats of those units. However, when variations involve multiple functionalization of the organic linkers or multiple metalation of metal-containing building units, it results in an aperiodic spatial arrangement of these variations, without altering the regularity of the MOF backbone. Such variance is represented by unique sequences of functionality or metal, and the very aperiodic nature of their spatial arrangement gives rise to anisotropy. These MOF constructs represent a new form of matter in which the sequences of such units are bound to an ordered backbone, thus adding complexity to an otherwise simple system, while preserving its overall crystallinity. It’s worth noting that, when a molecule capable of either continuous or multistate anisotropic motion is integrated within a sequence in a MOF, the resulting property goes beyond what is possible in simple systems. We term this emerging area ‘anisotropic reticular chemistry’. Introducing multiplicity and variation into the components of metal–organic frameworks has emerged as new fascinating directions in reticular chemistry. In this Review, the variances in the framework backbone, functionality and metal, and their leading to sequences of chemical information, are highlighted. Anisotropy in these structures is imposed by the variance and realized along a specific direction.