Pd-Catalyzed [4 + 1] Annulation Strategy to Functionalized 4-Methyleneproline Derivatives.

A Pd-catalyzed formal [4 + 1] cycloaddition reaction of sulfur ylides and in situ-generated Pd-stabilized zwitterions offers a convenient route to a series of functionalized proline derivatives. The utility of this method is demonstrated by a gram-scale synthesis and chemoselective functionalization of a proline-based derivative.

Asymmetric Synthesis of Functionalizable Type II ß-Turn-Inducing α-Amino Acid Building Blocks.

Peptidomimetics are emerging as a promising class of potent and selective therapeutics. Among the current approaches to these compounds, the utilization of constrained lactams is a key element in enforcing the active peptide conformation, and the development of efficient and stereocontrolled methods for generating such lactam building blocks is an important objective. Current methods typically rely on the elaboration of existing α-amino acids, and in so doing, the side chain is sacrificed during the ring-forming process. We report a new asymmetric approach to lactam-constrained α-amino acid building blocks bearing a range of polar and hydrophobic side chains. The chemistry is amenable to rapidly generating di- and tripeptides, and the potential for these lactams to stabilize type II ß-turns is demonstrated in the synthesis of the melanocyte-inhibiting factor peptidomimetic.

Selective Center Charge Density Enables Conductive 2D Metal-Organic Frameworks with Exceptionally High Pseudocapacitance and Energy Density for Energy Storage Devices.

Conductive 2D conjugated metal-organic frameworks (c-MOFs) are attractive electrode materials due to their high intrinsic electrical conductivities, large specific surface area, and abundant unsaturated bonds/functional groups. However, the 2D c-MOFs reported so far have limited charge storage capacity during electrochemical charging and discharging, and the energy density is still unsatisfactory. In this work, a strategy of selective center charge density to expand the traditional electrode materials to the electrode-electrolyte coupled system with the prototypical of 2D Co-catecholate (Co-CAT) is proposed. Electrochemical mechanism studies and density functional theory calculations reveal that dual redox sites are achieved with the quinone groups (CAT) and metal-ion linkages (Co-O) serving as the active sites of pseudocapacitive cation (Na+ ) and redox electrolyte species (SO3 2- ). The resultant electrode delivers an exceptionally high capacity of 1160 F g-1 at 1 A g-1 and a special self-discharge rate (86.8% after 48 h). Moreover, the packaged asymmetric device exhibits a state-of-the-art energy density of 158 W h kg-1 at the power density of 2000 W kg-1 and an excellent self-discharge rate of 80.6% after 48 h. This success will provide a new perspective for the performance enhancement for the 2D-MOF-based energy storage devices.

Highly efficient and selective photocatalytic reduction of nitroarenes using the Ni2P/CdS catalyst under visible-light irradiation.

A highly efficient and selective heterogeneous photocatalytic system for nitro reduction to amino organics was established using CdS, Ni2P and Na2S/Na2SO3 as a photosensitizer, a cocatalyst and a sacrificial electron donor in aqueous solution, respectively. Two competing pathways for photocatalytic H2 production and nitro reduction were found. Also, the reduction of nitroarenes to aniline was confirmed to proceed through both the direct and condensation routes.

Synthesis and properties of new luminescent hole transporting materials containing triphenylamine and carbazole units.

Two new blue luminescent hole transporting materials (HTM) containing triphenylamine, carbazole units and olefinic linkers (TM1 and TM2) were synthesized via Wittig reaction and characterized by (1)H NMR, FT-IR, and HRMS. The compounds show good solubility in common organic solvents such as dichloromethane, chloroform, tetrahydrofuran and dimethyl formamide. Their optical, electrochemical and crystalline properties were investigated by using UV-Vis, photoluminescence (PL) spectra, cyclic voltammetry (CV) and differential scanning calorimetry (DSC), respectively. Quantum-chemical calculation was performed to obtain their optimized structures and the electron distribution of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels. The UV-Vis absorption and PL spectra of the two compounds in solid state were found to be similar to that when they were in dilute THF, which suggests that these compounds remain as an amorphous state in solid films. CV measurements show that the two compounds embody suitable HOMO levels (in a range of -5.28 to -5.23 eV) for hole injection, which is consistent with the calculation consequence. Two compounds possess high glass-transition temperature (T(g)) at 96.61 and 90.74 °C for TM1 and TM2, respectively, suggesting the two compounds could form stable amorphous glassy states. The experimental results show that the synthesized compounds have great potential for application in organic light-emitting devices (OLEDs).