Insights into organic-inorganic hybrid molecular materials: organoimido functionalized polyoxomolybdates

Polyoxometalates (POMs) are polyatomic anions that comprise transition metal group 5 (V, Nb, Ta) or group 6 (Mo, W) oxyanions connected together by shared oxygen atoms. POMs are fascinating because of their exclusive and remarkable characteristics. One of the most interesting features of POMs is their capability to function as an electron relay by performing stepwise multi-electron redox reactions while maintaining their structural integrity. Functionalization of POMs with amino organic compounds results in organoimido derivatives of polyoxometalates, which have aroused interest due to augmentation of their properties. Comprehensive study has shown that the synthesis methodologies to obtain desired organoimido derivatives of POMs by employing various imido-releasing reagents have progressed drastically in recent decades, particularly the innovative DCC-dehydrating technique. These organoimido functionalized POMs have been used as major building blocks to develop unique nanostructured organic-inorganic hybrid molecular materials. Many conventional organic synthesis processes such as Pd-catalyzed carbon-carbon coupling and esterification reactions have been performed with organoimido functionalized POMs where the presence of POM triggered the reaction process. Thus, investigation of the reactivity of organoimido derivatives of POMs foreshadows the intriguing future of POMs chemistry.

Shining a light on the photo-sensitisation of organic-inorganic hybrid polyoxometalates

Finding new ways of using visible light (or, more specifically, solar irradiation) to drive commercially significant and/or challenging chemical processes is an ongoing research goal. Polyoxometalates (POMs) are discrete, metal-oxide clusters which are cheap, robust and easily synthesised but can also act as versatile molecular building blocks, allowing for astonishing variety in their structures and properties. In particular, the rich redox chemistry and inherent photo-activity of POMs makes them attractive for use in a variety of photochemical applications, however POMs characteristically only absorb strongly in the UV region. In this perspective, we discuss the various strategies which have been employed in order to sensitise POMs to visible light, with a particular focus on hybrid inorganic-organic POM species. We will discuss the two clear photo-activation mechanisms which have been developed to date and provide an outlook on some of the possible future directions of the field.

Evolutionary Metal Oxide Clusters for Novel Applications: Toward High-Density Data Storage in Nonvolatile Memories

Because of current fabrication limitations, miniaturizing nonvolatile memory devices for managing the explosive increase in big data is challenging. Molecular memories constitute a promising candidate for next-generation memories because their properties can be readily modulated through chemical synthesis. Moreover, these memories can be fabricated through mild solution processing, which can be easily scaled up. Among the various materials, polyoxometalate (POM) molecules have attracted considerable attention for use as novel data-storage nodes for nonvolatile memories. Here, an overview of recent advances in the development of POMs for nonvolatile memories is presented. The general background knowledge of the structure and property diversity of POMs is also summarized. Finally, the challenges and perspectives in the application of POMs in memories are discussed.

The first ReI organometallic complex with an organoimido-polyoxometalate ligand

An electrochemical, spectroscopic and theoretical study of the first Re^I complex with a hybrid organoimido-polyoxometalate ligand is presented.

Synthesis, structure, self-assembly and genotoxicity evaluation of a series of Mn-Anderson cluster based polyoxometalate–organic hybrids

A new series of POM–organic hybrids have been developed which show less genotoxicity compared to the parent polyoxometalate cluster.

N-alkylation of organo-imido substituted polyoxometalates: an efficient and stoichiometric approach for the easy post-modification of polyoxometalates

A high-yield post-functionalization protocol developed here provides an easy inclusion of the desired organic groups on a POM's highly negative surface.

Dye-sensitized polyoxometalate for visible-light-driven photoelectrochemical cells

A simple and facile one-step method for the synthesis of an organic dye-functionalized polyoxometalate (POM) hybrid with visible-light photo-response was reported.

Molecule-based water-oxidation catalysts (WOCs): cluster-size-dependent dye-sensitized polyoxometalates for visible-light-driven O2 evolution

From atomic level to understand the cluster-size-dependant behavior of dye-sensitized photocatalysts is very important and helpful to design new photocatalytic materials. Although the relationship between the photocatalytic behaviors and particles' size/shape has been widely investigated by theoretical scientists, the experimental evidences are much less. In this manuscript, we successfully synthesized three new ruthenium dye-sensitized polyoxometalates (POM-n, n relate to different size clusters) with different-sized POM clusters. Under visible-light illumination, all three complexes show the stable O2 evolution with the efficient order POM-3 > POM-2 > POM-1. This cluster-size-dependent catalytic behavior could be explained by the different numbers of M = Ot (terminal oxygen) bonds in each individual cluster because it is well-known that Mo = Ot groups are the catalytically active sites for photooxidation reaction. The proposed mechanism of water oxidation for the dye-sensitized POMs is radical reaction process. This research could open up new perspectives for developing new POM-based WOCs.

Synthesis and characterization of conjugated Dawson-type polyoxometalate-porphyrin copolymers

Hybrid polyoxometalate-porphyrin copolymeric films were obtained by the electro-oxidation of zinc octaethylporphyrin (ZnOEP) in the presence of a Dawson type polyoxophosphovanadotungstate bearing two pyridyl groups (POM(py)2). The synthesis of a series of POM(py)2 consisting of [P2W15V3O62](9-) functionalized with diol-amide or triol moieties, as well as the characterization of the copolymers are presented.

Inorganic–organic hybrid polymer with multiple redox for high-density data storage

A multi-redox polyoxometalate-based hybrid polymer has been demonstrated to show multilevel resistive switching memory behaviors.

Surfactant-thermal method to synthesize a novel two-dimensional oxochalcogenide

A new two-dimensional (2D) oxosulfide, (N2H4)2Mn3Sb4S8(μ3-OH)2 (1), has been successfully synthesized under surfactant-thermal conditions with hexadecyltributylphosphonium bromide as the surfactant. Compound 1 has a layered structure and contains a novel [Mn3(μ3-OH)2]n chain along the b-axis. The photocatalytic activity for compound 1 has been demonstrated under visible-light irradiation and continuous H2 evolution was observed. Our results indicate that surfactant-thermal synthesis could be a promising method for growing novel crystalline oxochalcogenides with interesting structures and properties.