Directed Synthesis of Stable Large Polyoxomolybdate Spheres

Abstract

Polyoxometalates or POMs, a class of inorganic transition metal-oxide based clusters, have gained significant interest owing to their catalytic, magnetic, and material science applications. All such applications require high surface area POM based materials. However, chemically synthesized POMs are still at most in the range of a few nanometers, with their size and morphology being difficult to control. Hence, there is an immediate need to develop design principles that allow easy control of POM morphology and size on mesoscopic (50-500 nm) length scales. Here, we report a design strategy to meet this need. Our method reported here avoids a complex chemical labyrinth by using a prefabricated cationic 1,2-dioleol-3-trimethylammonium-propane (DOTAP) vesicle as a scaffold/structure directing agent and gluing simple anionic heptamolybdates by electrostatic interaction and hydrogen bonds to form large POM spheres. By this method, complexity in the resulting structure can be deliberately induced either via the scaffold or via the oxometalate. The high degree of control in the matter of the size and morphology of the resulting POM superstructures renders this method attractive from a synthetic standpoint.

“SOFT OXOMETALATES” (SOMs): A VERY SHORT INTRODUCTION

“…In that example, a prefabricated cationic vesicle is used as a scaffold/structure directing agent and glues simple anionic oxomolybdates by electrostatic interaction and hydrogen bonds to form large DeSOM spheres. [33] (Figure 2) By this method, complexity in the resulting structure can be deliberately This picture is further consistent with the surface area of DOTAP [34] and heptamolybdate [1] reported in the literature. So, the DeSOM supersphere is most likely a vesicular DOTAP covered with a heptamolybdate monolayer where every three DOTAP molecules bind with one heptamolybdate of the monolayer.…”

“…All the above DeSOMs were characterized by using a multitude of different Mo=O groups pointing toward the C=O) is implied. For details please refer [32] and [33].…”

Photochemical reduction of carbon dioxide coupled with water oxidation using various soft-oxometalate (SOM) based catalytic systems

“…Such vesicle-like super-structure formation of the metal oxide clusters is well known and studied by our group and we have proposed them to be called so-oxometalates (SOMs). [43][44][45][46][47][48][49][50] Very recently we have exploited various properties of SOMs and thereby, their usability in a large range of applications have been explored. SOMs can undergo topological transformation, 51 can be used in patterning 52,53 and as active particles.…”

Two linear trinuclear clusters with bridging triazole: crystal structure and magnetism

“…The exchange parameters lie in the range observed for 4-substituted triazoles, which might be expected from the similarity of the overall structures of the compounds. Further research is in progress to produce other clusters based on triazoles; future directions might include attaching clusters on the surface of colloids with suitable complementary charge as shown with other metal clusters and to observe the magnetic behaviors thereof [35][36][37].…”