Soft Materials with Diverse Suprastructures via the Self-Assembly of Metal–Organic Complexes

Abstract

CONSPECTUS: Inspired by assemblies in the natural world, researchers have prepared diverse suprastructures with distinct spatial arrangements by artificial self-assembly, including micelles, vesicles, ribbons, films, fibers, and tubes. The field of assembly is undergoing a transition from single-component to multicomponent assembly and single-step to multistep processing. Control over the size, shape, and composition of these building blocks has enabled the formation of suprastructures with substantial structural diversity. More importantly, harnessing noncovalent interactions to create suprastructures in a controlled manner will lead to a better understanding of the formation of complex self-organized patterns. However, for the construction of multiscale self-assemblies with controllable shapes and functions, the selection of a suitable protocol remains challenging. Coordination-driven self-assembly provides a bottom-up approach to construct various metal-organic complexes (MOCs), which could be further used as building blocks with controllable shapes and sizes. Despite the tremendous progress made in the design of MOC-based supramolecular materials, most of these MOCs have dimensions of only several nanometers, and investigations of these structures rely on the characterization of their crystal structure. However, most of the functional suprastructures in living organisms have dimensions ranging from microns to centimeters and have the form of soft materials. Thus, obtaining MOC-based highly ordered materials of larger size remains a challenge. This Account focuses on our recent advances in the construction of soft suprastructure materials with MOCs. A series of functionalized MOCs were first constructed through coordination-driven self-assembly. Then, further self-assembly of the as-prepared MOCs gave rise to the formation of higher-order structures. By changing the functional groups in the acceptors and donors in the MOCs, different suprastructures, including nanospheres, nanodiamonds, nanorods, nanofibers, membranes, films, and gels, were prepared. These studies suggest that using MOCs as building blocks is a highly efficient strategy to achieve complex architectures and functional materials for the development of desired MOC-based soft materials with high precision and fidelity.

Exploring the self-assembly of dumbbell-shaped polyoxometalate hybrids, from molecular building units to nanostructured soft materials

“…The development of nanostructured so materials through hierarchical self-assembly is drawing growing attention of scientists inspired by the structural complexity of natural systems. [1][2][3] These compounds involve a variety of interaction combinations that can lead to the emergence of innovative structures or even functionalities. 4 Classical synthetic strategies of such articial assemblies with multiple levels of organization rely on the use of molecular building units displaying orthogonal and switchable interactions (e.g.…”

Cyclodextrins Modified/Coated Metal–Organic Frameworks

“…Metal-organic frameworks (MOFs) are ordered porous solid crystalline coordination polymers [1], fabricated by polycomplexing linkers including carboxylate, phosphonates, sulfonates and imidazolates with easily tunable compositions such as various metal cations, and have wide applications in gas storage [2], separation and catalysis [1]. However, there are still some limitations and challenges for (1) preparing MOFs, e.g., usually requiring high reaction temperature and long reaction time [3], (2) tuning porosities of MOFs without affecting its stability, e.g., via external stimuli [4], as well as (3) applying MOFs to biomedicines or environmental areas in aqueous atmosphere, e.g., with poor colloidal stability [5]. Thus, moderate synthesis conditions, as well as additional functionalization of MOFs with biofriendly or stimuli-responsive moieties are highly desired, not only to control pore sizes and shapes [6,7], but also to provide the possibility of adjusting physiochemical properties of MOFs such as aqueous solubility and bioactivity [3].…”

Pillararenes Trimer for Self-Assembly

“…Self-assembly has attracted much more attention in fundamental researches of material science and interesting applications to practical engineering areas [1,2], e.g., providing not only inspiring methodological strategy in processing, but also solid functional materials to balance morphologies and properties [3]. Building ideal self-assembly begins from the molecular level [2,4,5], i.e., designing the structural geometry of molecules, modifying them with proper functional moieties, introducing and choosing proper inter/intramolecular interactions, as well as controlling the behavior of assembled molecules. Thus, designing appropriate building blocks from the molecular level is very significant in the construction of multi-dimensional self-assembly [2].…”

“…Building ideal self-assembly begins from the molecular level [2,4,5], i.e., designing the structural geometry of molecules, modifying them with proper functional moieties, introducing and choosing proper inter/intramolecular interactions, as well as controlling the behavior of assembled molecules. Thus, designing appropriate building blocks from the molecular level is very significant in the construction of multi-dimensional self-assembly [2].…”