Atomically precise nanoclusters with reversible isomeric transformation for rotary nanomotors

Thermal-stimuli responsive nanomaterials hold great promise in designing multifunctional intelligent devices for a wide range of applications. In this work, a reversible isomeric transformation in an atomically precise nanocluster is reported. We show that biicosahedral [Au13Ag12(PPh3)10Cl8]SbF6 nanoclusters composed of two icosahedral Au7Ag6 units by sharing one common Au vertex can produce two temperature-responsive conformational isomers with complete reversibility, which forms the basis of a rotary nanomotor driven by temperature. Differential scanning calorimetry analysis on the reversible isomeric transformation demonstrates that the Gibbs free energy is the driving force for the transformation. This work offers a strategy for rational design and development of atomically precise nanomaterials via ligand tailoring and alloy engineering for a reversible stimuli-response behavior required for intelligent devices. The two temperature-driven, mutually convertible isomers of the nanoclusters open up an avenue to employ ultra-small nanoclusters (1 nm) for the design of thermal sensors and intelligent catalysts.

Optical Properties and Stability of Bilayer Rubrene-Alq3 Films Fabricated by Vacuum Deposition

We report on the optical and structural characterization of the two-component vacuum deposited (VD) rubrene (Rub)-Alq3 films. As is known, Rub-doped OLED active materials demonstrate both promising electroluminescence and transistor characteristics. However, in terms of operational lifetime, the Rub practical application in basic devices has a few draw-backs related to its chemical instability. Our main attention was focused on the role of the Alq3 coverage and the isomeric transformation of a Rub molecule on its chemical stability in these structures. By monitoring the evolution of PL emission in time, we found that the Rub degradation in Rub-Alq3 films is slower than that in vacuum-deposited Rub layers. These results demonstrate that the deposition of an Alq3 layer can be a way to enhance the stability of Rub to the photo-oxidation in optoelectronic devices. The Rub amorphous film crystallization at elevated temperatures in open air was observed for the first time.