Polyoxometalate Clusters: Sub-nanometer Building Blocks for Construction of Advanced Materials

Abstract

Cluster-assembled materials based on polyoxometalates (POMs) process unprecedented structural tunability and polymer-like behaviors because of the sub-nanometer-sized building blocks and their non-covalent linkage. Through the whole journey in their development, exquisite POM cluster assemblies with advanced functions spring up, and the control over their nanostructures tends to be more precise and reach their nature at molecular level. In this paper, recent progress in cluster-assembled materials based on POMs is overviewed, including the assembly of covalently and non-covalently modified POM clusters as well as the co-assembly of POM clusters and inorganic entities. By surfactant encapsulation, POM clusters are compatible in various solvents, and hybrid assemblies with diverse morphologies and unique properties have been achieved. The Janus POM-POSS clusters feature intricate assemblies in mixed solvent systems, which provide instructive understanding for solution behaviors of macro-ions. Notably, the POM clusters can also intervene in the nucleation of nanocrystals, resulting in the formation of cluster-nuclei co-assembled materials with well-organized structures and wide-ranging composition compatibility. Meanwhile, the chemistry of cluster-assembled materials has not been well explored, and there are great potentials as well as challenges that lie ahead.

Triblock Copolymer/Polyoxometalate Nanocomposite Electrolytes with Inverse Hexagonal Cylindrical Nanostructures

“…Besides the aforementioned ionic additives for block copolymers, polyoxometalates (POMs), the nanosized, anionic molecularly defined clusters of metal oxides have attracted much attention for their abilities in inducing phase transitions as multi‐charged ions and fabricating functional hybrid polymer materials as typical inorganic moieties. [ 23–36 ] Recently, their high proton conductivity, thermal stability and water‐retention capability have been appealing for nanostructured proton‐conducting polymer hybrid electrolytes. [ 37–40 ] For example, Guiver et al.…”

Multiscale Assembly of [AgS4] Tetrahedrons into Hierarchical Ag–S Networks for Robust Photonic Water

“…[ 8–12 ] In addition to the latest developments in atomically precise ultrasmall particles (mainly limited to below 3 nm), there is also a need to realize their programmable structure (or self‐assembly) into functional materials with a high level of hierarchy, complexity, and accuracy, up to the micro‐ or even macroscale. [ 13–20 ] This multiscale assembly of atomically precise ultrasmall particles provides a reliable platform for the bottom‐up construction of artificial functional materials across all scales, which is an intrinsic requirement for manifesting universal functionality in nature and life. [ 21–23 ] In addition, it also enables the assembly to have imposed stability, collective (and often synergistic) functionality, and expected processability, thereby increasing their acceptance in various fields of practical applications.…”

“…In this context, with continuous progress, several feasible strategies have been deployed: 1) using various directing agents to perform long‐distance self‐assembly/crystallization of atomically precise ultrasmall particles through weak forces (e.g., dipolar, van der Waals, and supramolecular interactions), where the surface chemistry and the specific colloidal environment of the atomically precise ultrasmall particles are keys to the success of this method; [ 13,14,24–26 ] 2) introducing predesigned organic linkers to coordinate with atomically precise ultrasmall particles to construct periodically extended solids, which usually have well‐defined geometry and connectivity; [ 27–29 ] and 3) using a neat polymerization of atomically precise ultrasmall particles through effective homogeneous or heterogeneous metallophilic interactions, which are usually observed in single crystals. [ 30,31 ] These obtained atomically precise ultrasmall particles based micro‐/macroscale materials have shown impressive performance in optical, electronic, and catalytic applications.…”

Molybdenum–Tungsten Blue Nanoparticles as a Precursor for Ultrafine Binary Carbides

“…Polyoxometalate complexes have a fixed size of the order of 3–5 nm [ 16 , 17 , 18 , 19 , 20 , 21 ]. Today, the class of polyoxometalate complexes is being actively studied, and structures of various compositions, shapes, and sizes were previously obtained [ 22 , 23 , 24 , 25 , 26 ]. Research found that polyoxometalates containing molybdenum are formed as a result of the self-assembly process from the initial building blocks Mo 1 , Mo 2 , Mo 8 , etc.…”