We report a green and efficient method for chemoselective deoxidization of graphene oxide via the ultraviolet irradiation catalyzed with 2,2,6,6-tetramethyl-4-piperidinol. While the sp(2)-hybridized oxygen functional groups are removed after the reduction, the epoxy and hydroxyl groups are retained in the chemoselectively reduced graphene oxide (CrGO). The obtained CrGO nanosheets exhibit the high solubility and excellent electronic stability, which allows for the fabrication of thin film devices through a solution processing. As a proof of concept, a CrGO-based write-once-read-many-times memory device with the desirable stability and long-time operation is fabricated.

Nonplane molecules with multiple large aromatic planes could be promising candidates to form various polyhedral micro/nanocrystals by manipulating the different π···π stacking, tuning the cohesive energies of crystal facets, and controlling the kinetic growth process. Spirocyclic aromatic hydrocarbons (SAHs) not only have two cross-shaped aromatic planes but also offer the feature of supramolecular steric hindrance, making it favorable for the heterogeneous kinetic growth into highly symmetric polyhedra. Herein, we report that a novel SAH compound, spiro[fluorene-9,7'-dibenzo[c,h]acridine]-5'-one (SFDBAO), can self-assemble into various monodispersed shapes such as hexahedra, octahedra, and decahedra through the variation of either different types of surfactants, such as Pluronic 123 (P123) and cetyltrimethyl ammonium bromide (CTAB), or growth parameters. In addition, the possible mechanism of crystal facet growth has been proposed according to the SEM, XRD, TEM, and SAED characterization of organic polyhedral micro/nanocrystals. The unique cruciform-shaped SAHs have been demonstrated as fascinating supramolecular synthons for various highly symmetric polyhedral assembling.

Supramolecular steric hindrance designs make pyrene-functionalized spiro[fluorene-9,7'-dibenzo[c,h]acridine]-5'-one (Py-SFDBAO) assemble into 2D nanostructures that facilitate aqueous phase large-area synthesis of high-quality and uniform crystalline thin films. Thin-film diodes using aqueous nanosheets as active layers exhibit a non-volatile bistable electrical switching feature with ON/OFF ratios of 6.0 × 10(4) and photoswitching with conductive gains of 10(2) -10(3). Organic nanosheets are potentially key components for eco-friendly aqueous dispersed organic nano-inks in the application of printed and flexible electronics.

Negative thermal expansion (NTE) is an abnormal physical behavior that has promising applications for high precision thermal control. Since Prussian blue analogues have the two central linking atoms of -C≡N-, they have large structure exibility and are suitable to explore new NTE materials. However, understanding the nature of structure exibility from the point of view of chemical bonding is important and urgent. Here, we adopt for the rst time rst-principles calculations to predict that the cubic TiCo(CN) 6 and ScCo(CN) 6 have NTE behavior. The calculated results for M in MCo(CN) 6 (M = Fe, Ti and Co) indicated that the Sc-N bond is the strongest, but with the weakest direction dependence among the M-N bonds in the three systems. The lattice dynamics calculations results revealed that the low-frequency phonon vibration modes for NTE in MCo(CN) 6 have much stronger relationship with the M-N bond feature. The present work reveals the important role of the related bond in the NTE open-framework materials.

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