Self-assembly of m-phenylenediamine and polyoxometalate into hollow-sphere and core-in-hollow-shell nanostructures for selective adsorption of dyes

Abstract

Supramolecular self-assembly is an effective method to assemble organic and inorganic units into various hierarchical structures with excellent properties and is widely used in material and life science. In this article, the self-assembled hollow-sphere and core-in-hollow-shell nanostructures composed of m-phenylenediamine and a novel Preyssler-type polyoxometalates (POM, K12.5Na1.5[NaP5W30O110]·15H2O (abbreviated as P5W30)) without template were successfully realized by adjusting the non-covalent interactions. For comparison, we also selected o-phenylenediamine and p-phenylenediamine to investigate whether isomerides have different effects on the self-assembly behavior with P5W30. The results indicated that only m-phenylenediamine/P5W30 can form hollow spheres and core-in-hollow-shell structure while o-phenylenediamine/P5W30 and p-phenylenediamine/P5W30 cannot which revealed that the self-assembly process can be regulated via isomer effects. Moreover, the detailed analysis of the formation of hollow spheres and core-in-hollow-shell structure are studied and the mechanism is mainly due to the Ostwald ripening. In addition, m-phenylenediamine/P5W30 composite has a good adsorption capacity for methylene blue (MB) dyes, even in the presence of other dyes such as rhodamine B (RB) and amaranth (AR). Our findings further confirmed that supramolecular self-assembly between organic molecules and POM can unique a distinctive “bottom-up” strategy to construct diversiform structures with functional properties.