Revisiting the Hitherto Elusive Cyclohexanehexone Molecule: Bulk Synthesis, Mass Spectrometry, and Theoretical Studies.

The cyclohexanehexone (C6O6) octahydrate molecule was claimed to be synthesized as early as 1862. However, the chemical in the 1862 study and the chemicals used in most of the existing studies and sold by most chemical vendors are actually dodecahydroxycyclohexane dihydrate (C6(OH)12·2H2O). Here we revisit our bulk synthesis method of C6O6 by the dehydration of the C6(OH)12·2H2O material, and report the mass spectrum of C6O6 that has been highly challenging to obtain owing to its high sensitivity toward ambient conditions. A new home-built electrospray ionization mass spectrometry setup in a glovebox is utilized to detect C6O6 in the form of C6O6H-. Tandem mass spectrometry MSn (n = 2-4) presents consecutive losses of CO molecules, further confirming the structure of C6O6. Theoretical calculations are performed to recover the chemical bonding of C6O6 and to rationalize the synthetic method. This work provides a benchmark understanding of the historically elusive C6O6.

A Two-Dimensional Metal-Organic Polymer Enabled by Robust Nickel-Nitrogen and Hydrogen Bonds for Exceptional Sodium-Ion Storage.

Organic electrode materials suffer from low electronic conductivity and poor structure stability. Herein, a metal-organic polymer, Ni-coordinated tetramino-benzoquinone (Ni-TABQ), is synthesized via d-π hybridization. The polymer chains are stitched by hydrogen bonds to feature as a robust two-dimensional (2D) layered structure. It offers both electron conduction and Na+ diffusion pathways along the directions of the polymer chains and the hydrogen bonds. With both the conjugated benzoid carbonyls and imines as the redox centers for the insertion and extraction of Na+ , the Ni-TABQ delivers high capacities of about 469.5 mAh g-1 at 100 mA g-1 and 345.4 mAh g-1 at 8 A g-1 . The large capacities are sustained for 100 cycles with almost 100 % coulombic efficiencies. The exceptional electrochemical performance is attributed to the unique 2D electron conduction and Na+ diffusion pathways enabled by the robust Ni-N and hydrogen bonds.

A High-Power Aqueous Zinc-Organic Radical Battery with Tunable Operating Voltage Triggered by Selected Anions.

In contrast to traditional rechargeable rock-chair metal-ion batteries, dual-ion batteries (DIBs) involve redox reactions with anions rather than cations in p-type cathodes. In principle, regulating the electrochemical performance of the DIB by different anion species is highly feasible. Herein, the anion effect on the electrochemical performance of a DIB, the aqueous Zn- organic radical battery (Zn-ORB), consisting of a poly(2,2,6,6tetramethylpiperidinyloxy-4-yl vinyl ether) cathode and a Zn anode, was investigated by DFT calculations. SO4 2- , CF3 SO3 - , and ClO4 - with different molecular electrostatic potential values were selected as anion models. DFT calculations revealed that a stronger electrostatic interaction of the anion with the organic radical resulted in a higher operating voltage of the Zn-ORB, which was consistent with experimental results. These results bring new insight into the redox chemistry of p-type organic radicals with anions and will promote the development of high-power aqueous Zn-ORBs as well as inspire more investigations into the anion effect towards novel battery designs.

Cyclohexanehexone with Ultrahigh Capacity as Cathode Materials for Lithium-Ion Batteries.

Organic carbonyl compounds show potential as cathode materials for lithium-ion batteries (LIBs) but the limited capacities (<600 mA h g-1 ) and high solubility in electrolyte restrict their further applications. Herein we report the synthesis and application of cyclohexanehexone (C6 O6 ), which exhibits an ultrahigh capacity of 902 mA h g-1 with an average voltage of 1.7 V at 20 mA g-1 in LIBs (corresponding to a high energy density of 1533 Wh kg-1 C 6 O 6 ). A preliminary cycling test shows that C6 O6 displays a capacity retention of 82 % after 100 cycles at 50 mA g-1 because of the limited solubility in high-polarity ionic liquid electrolyte. Furthermore, the combination of DFT calculations and experimental techniques, such as Raman and IR spectroscopy, demonstrates the electrochemical active C=O groups during discharge and charge processes.

Mesoscale Graphene-like Honeycomb Mono- and Multilayers Constructed via Self-Assembly of Coclusters.

Honeycomb structure endows graphene with extraordinary properties. But could a honeycomb monolayer superlattice also be generated via self-assembly of colloids or nanoparticles? Here we report the construction of mono- and multilayer molecular films with honeycomb structure that can be regarded as self-assembled artificial graphene (SAAG). We construct fan-shaped molecular building blocks by covalently connecting two kinds of clusters, one polyoxometalate and four polyhedral oligomeric silsesquioxanes. The precise shape control enables these complex molecules to self-assemble into a monolayer 2D honeycomb superlattice that mirrors that of graphene but on the mesoscale. The self-assembly of the SAAG was also reproduced via coarse-grained molecular simulations of a fan-shaped building block. It revealed a hierarchical process and the key role of intermediate states in determining the honeycomb structure. Experimental images also show a diversity of bi- and trilayer stacking modes. The successful creation of SAAG and its stacks opens up prospects for the preparation of novel self-assembled nanomaterials with unique properties.

A mild and efficient direct α-amination of ß-dicarbonyl compounds using iodosobenzene and p-toluenesulfonamide catalyzed by perchlorate zinc hexahydrate.

A direct α-amination of ß-dicarbonyl compounds has been achieved by using iodosobenzene (PhIO) as an oxidant and p-toluenesulfonamide (TsNH(2)) as an aminating reagent in the presence of a catalytic amount of perchlorate zinc hexahydrate. The present amination reaction proceeds quickly at rt (<30 min needed for most tested substrates) to provide the corresponding α-N-tosylamido ß-dicarbonyl compounds in high to excellent yields.