Assembling metal-organic framework (MOF)-based particles is an emerging approach for creating colloidal superstructures and hierarchical functional materials. However, realization of this goal requires strategies that not only regulate particle interactions but also harness the anisotropic morphologies and functions of various frameworks. Here, by exploiting depletion interaction induced by ionic amphiphiles, we show the assembly of a broad range of low-dimensional MOF colloidal superstructures, including 1D straight chains, alternating or bundled chains, 2D films of hexagonal, square, centered rectangular, and snowflake-like architectures, and quasi-3D supercrystals. With well-defined polyhedral shapes, the MOF particles are mutually oriented upon assembly, producing super-frameworks with hierarchically coordinated crystallinity and micropores. We demonstrate this advantage by creating functional MOF films with optical anisotropy, in our cases, birefringence and anisotropic fluorescence. Given the variety of MOFs available, our technique should allow access to advanced materials for sensing, optics, and photonics.

Introducing the concept of programmability paves the way for designing complex and intelligent materials, where the materials’ structural information is pre-encoded in the components that build the system. With highly tunable interactions, DNA-coated particles are promising building elements to program materials at the colloidal scale, but several grand challenges have prevented them from assembling into the desired structures and phases. In recent years, the field has seen significant progress in tackling these challenges, which has led to the realization of numerous colloidal structures and dynamics previously inaccessible, including the desirable colloidal diamond structure, that are useful for photonic and various other applications. We review this exciting progress, focusing in detail on how DNA-coated colloids can be designed to have a sophisticatedly tailored surface, shape, patches, as well as controlled kinetics, which are key factors that allow one to program in principle a limitless number of structures. We also share our view on how the field may be directed in future.

Colloidal micromotors can autonomously propel due to their broken symmetry that leads to unbalanced local mechanical forces. Most commonly, micromotors are synthesized to possess a Janus structure or its variants, having two components distinct in shape, composition, or surface joined together on opposite sides. Here, we report on an alternative approach for creating micromotors, where microcrystals of metal–organic frameworks (MOFs) with various polyhedral shapes are propelled under an AC electric field. In these cases, symmetry breaking is realized by orienting the polyhedral particles in a unique direction to generate uneven electrohydrodynamic flow. The particle orientations are controlled by a delicate competition between the electric and gravitational forces exerted on the particle, which we rationalize using experiments and a theoretical model. Furthermore, by leveraging the MOF types and shapes, or surface properties, we show that the propulsion of MOF motors can be tuned or reversed. Because of the flexibility in designing MOFs and their one-step scalable synthesis, our strategy is simple yet versatile for making well-defined functional micromotors.