Creating Quasi Two-Dimensional Cluster-Assembled Materials through Self-Assembly of a Janus Polyoxometalate-Silsesquioxane Co-Cluster

Wu, H (Wu, Han)^[ 1,2 ] ; Zhang, YQ (Zhang, Yu-Qi)^[ 1,2 ] ; Hu, MB (Hu, Min-Biao)^[ 1,2 ] ; Ren, LJ (Ren, Li-Jun)^[ 1,2 ] ; Lin, Y (Lin, Yue)^[ 4 ] ; Wang, W(Wang, Wei)^[ 1,2,3 ]

LANGMUIR, 2017, 33(21): 5283-5290

DOI: 10.1021/acs.langmuir.7b01015

 WOS:000402581700022

Abstract

Clusters are an important class of nanoscale molecules or superatoms that exhibit an amazing diversity in structure, chemical composition, shape, and functionality. Assembling two types of clusters is creating emerging cluster-assembled-materials (CAMs). In this paper, we. report an effective approach to produce quasi two-dimensional (2D) CAMs of two types of spherelike clusters, polyhedral oligomefic sllsesquioxanes (POSS), and poly-oxometalates (POM). To avoid macrophase separation between the two clusters, they are covalently linked to form a POM POSS cocluster with Janus characteristics and a dumbbell shape. This Janus characteristics enables the cocluster to self-assemble into :diverse nanoaggregates, as conventional amphiphilic molecules and macromolecules do, in selective solvents. In our study, we obtained micelles, vesicles, nariosheets, and nanoribbons by tuning the n-hexane content in mixed solvents of acetone and n-hexane. Ordered packing of clusters in the nanosheets and nanoribbons were directly. visualizedusing high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) technique. We infer that the increase of packing order results in :the vesicle-to-sheet transition and the change in packing mode causes the sheet-to-ribbon transitions. Our findings have verified the effectivity of creating quasi 2D cluster-assembled materials though the cocluster self-assembly as a new approach to produce novel CAMs.