Single‐Crystal Superstructures via Hierarchical Assemblies of Giant Rubik's Cubes as Tertiary Building Units

Abstract

Intricate superstructures possess unusual structural features and promising applications. The preparation of superstructures with single-crystalline nature are conducive to understanding the structure-property relationship, however, remains an intriguing challenge. Herein we put forward a new hierarchical assembly strategy towards rational and precise construction of intricate single-crystal superstructures. Firstly, two unprecedented superclusters in Rubik's cube's form with a size of � 2 × 2 × 2 nm 3 are constructed by aggregation of eight {Pr 4 Sb 12 } oxohalide clusters as secondary building units (SBUs). Then, the Rubik's cubes further act as isolable tertiary building units (TBUs) to assemble diversified single-crystal superstructures. Importantly, intermediate assembly states are captured, which helps illustrate the evolution of TBU-based superstructures and thus provides a profound understanding of the assembly process of superstructures at the atomic level.

Plasma Regeneration of Spent Pd/Al2O3 Catalysts and Their Electrochemical Performance

“…It is worth noting that compared with the untreated spent catalyst, several small peaks in the range of 20–30° appear to weaken to different degrees or even eliminated for the catalyst treated with the plasma under three different atmospheres. This observation seems to be related to the coke removal, where crystalline carbon black is reported to exhibit diffraction peaks in the range of 20–30°. , In addition, after the plasma treatment under different atmospheres, the spent catalyst powder changed from the original brown (Figure S1a) into clay brown under the Ar condition (Figure S1b), plain brown under the O 2 condition (Figure S1c), and red brown (Figure S 1d) under the N 2 condition, respectively.…”

“…This observation seems to be related to the coke removal, where crystalline carbon black is reported to exhibit diffraction peaks in the range of 20−30°. 30,31 In addition, after the plasma treatment under different atmospheres, the spent catalyst powder changed from the original brown (Figure S1a) into clay brown under the Ar condition (Figure S1b), plain brown under the O 2 condition (Figure S1c), and red brown (Figure S 1d) under the N 2 condition, respectively. Figure 6a illustrates the results of thermogravimetry (TGA) oxidation analysis, together with the corresponding first derivative thermogravimetry (DTG) profiles in Figure 6b.…”

Structural Evolution and Properties of Praseodymium Antimony Oxochlorides Based on a Chain-like Tertiary Building Unit

“…The high purity of the title compounds was well demonstrated by the fact that the experimental PXRD pattern matched well with the calculated results from the single-crystal X-ray diffraction data ( Figure 6 ), along with various characterizations, such as elemental analysis (EA) and TGA. Note that the PXRD patterns feature broad and low-intensity diffraction peaks, which are common for these types of high-nuclearity cluster-based compounds [ 8 , 23 , 24 , 25 , 26 ]. The TGA for compounds 1 and 3 was carried out under a nitrogen atmosphere in the temperature range of 20–1000 °C ( Figure S3 ).…”

“…Therefore, it is important to search for new secondary building units (SBUs), and even tertiary building units (TBUs), for assembling complex structures. Meanwhile, systematical demonstration of structural evolution at the atomic level is meaningful to understand the assembly process and, therefore, help to design new intricate structures [ 8 ]; however, this remains a challenge because of the difficulty in obtaining precise or single-crystalline structures in each hierarchical level.…”

“…Subsequently, by changing the reaction conditions and introducing organic carboxylic acid ligands as bridging linkers to replace the terminally coordinated Cl − ions, the {Pr 4 Sb 12 } clusters could act perfectly as SBUs to assemble diversiform compounds with one-dimensional (1-D) helical chain-like, ribbon-like, or tubular structure; two-dimensional (2-D) layered structure; and three-dimensional (3-D) interspersed or porous structure [ 24 , 25 , 26 ]. Very recently, we have isolated two giant superclusters in the form of the Rubik’s cube by eight-aggregation of {Pr 4 Sb 12 } clusters as SBUs, and the superclusters further acted as TBUs to construct a series of superstructures [ 8 ]. Importantly, we were able to isolate two intermediate superstructures with coexisting SBUs and TBUs in distinct single-crystalline form, which helped in revealing the structural evolution of superstructures at the atomic level.…”