Volume 10 Issue 12, December 2018

Volume 10 Issue 12

Sulfone so good for COF catalysis

Although organic photocatalysts are an attractive option for water splitting because they can be tuned relatively easily through synthesis, they tend not to be very efficient. Now, a team led by Andrew Cooper has shown that a covalent organic framework (COF) comprising β-ketoenamine nodes and benzothiophene sulfone-based linkers is a good hydrogen-evolution catalyst (an artistic representation of the process is shown on the cover). Its activity — attributed to the COF’s crystallinity, strong visible-light absorption and the wettable, hydrophilic nature of its sulfone-lined mesopores — can be further improved by dye sensitization.

See Wang et al.

Image: Adam Kewley, adamkewley.com. Cover Design: Tulsi Voralia.

News & Views

  • News & Views |

    Superoxide dismutase mimics can help regulate the levels of O2•− in the body, but typically rely on redox-active metals that are toxic in their free form. Now, a complex featuring a redox-active quinol moiety complexed to a redox-inactive zinc centre has been shown to catalyse O2•− dismutation.

    • Diane E. Cabelli
  • News & Views |

    Covalent organic frameworks (COFs), whose heterogeneous backbones can be easily tuned at the molecular level, are promising photocatalysts for artificial photosynthesis. Sulfone-rich crystalline, wettable COFs have now been shown to exhibit high photocatalytic hydrogen evolution rates with platinum nanoparticles as co-catalysts.

    • Tanmay Banerjee
    •  & Bettina V. Lotsch
  • News & Views |

    Magnetic or electric fields have long been used to align or orient atomic or molecular species in a molecular beam. Now, experiments in a merged beam apparatus show that an external magnetic field can be used to favour one particular reaction path.

    • Astrid Bergeat
    •  & Christian Naulin

Articles

  • Article |

    The inherent synthetic tuneability of organic materials makes them attractive in photocatalysis, but they tend to have low quantum efficiencies for water splitting. A crystalline covalent organic framework featuring a benzo-bis(benzothiophene sulfone) moiety has now been shown to exhibit high activity for photochemical hydrogen evolution from water.

    • Xiaoyan Wang
    • , Linjiang Chen
    • , Samantha Y. Chong
    • , Marc A. Little
    • , Yongzhen Wu
    • , Wei-Hong Zhu
    • , Rob Clowes
    • , Yong Yan
    • , Martijn A. Zwijnenburg
    • , Reiner Sebastian Sprick
    •  & Andrew I. Cooper
  • Article |

    Steric effects in a fundamental energy-transfer reaction at collision energies from over 1,000 K down to 20 mK have now been studied. At high energies a pronounced dependence of the reactivity on the reactant orientation is observed, but this effect is not present at the lowest energies because of dynamic reorientation.

    • Sean D. S. Gordon
    • , Juan J. Omiste
    • , Junwen Zou
    • , Silvia Tanteri
    • , Paul Brumer
    •  & Andreas Osterwalder
  • Article |

    So far, monosubstituted carbenes have only been spectroscopically characterized at very low temperatures. Now, it has been shown that a bulky, chemically inert, amino substituent is enough to tame the intrinsic tendency of carbenes towards dimerization, enabling their isolation at room temperature.

    • Ryo Nakano
    • , Rodolphe Jazzar
    •  & Guy Bertrand
  • Article |

    A 27 kDa photosensitizer protein (PSP) has now been developed and used to design a miniature photocatalytic CO2-reducing enzyme. Visible light drives the PSP efficiently to the long-lived triplet excited state (PSP*), and then to a super-reducing radical (PSP), which is strong enough to reduce many CO2-reducing catalysts. The 3D structure of PSP at 1.8 Å resolution was determined by X-ray crystallography.

    • Xiaohong Liu
    • , Fuying Kang
    • , Cheng Hu
    • , Li Wang
    • , Zhen Xu
    • , Dandan Zheng
    • , Weimin Gong
    • , Yi Lu
    • , Yanhe Ma
    •  & Jiangyun Wang
  • Article |

    Catalytic superoxide dismutase mimics typically involve manganese centres. Now, a complex based on redox-inactive zinc(ii) and a redox-active quinol ligand is found to catalytically degrade superoxide. The reaction, proposed to occur through oxidation of the ligand to a quinoxyl radical, is hastened rather than inhibited by the presence of phosphate.

    • Meghan B. Ward
    • , Andreas Scheitler
    • , Meng Yu
    • , Laura Senft
    • , Annika S. Zillmann
    • , John D. Gorden
    • , Dean D. Schwartz
    • , Ivana Ivanović-Burmazović
    •  & Christian R. Goldsmith
  • Article |

    Inhibiting the interaction between amyloid-β (Aβ) and a neuronal cell surface receptor, LilrB2, could offer a potential route for treating Alzheimer’s disease. Now, binding sites between Aβ and LilrB2 have been discovered and computational selection has identified inhibitors that block this binding site. Cell-penetrating inhibitors were found to block the Aβ–LilrB2 interaction and limit Aβ-induced cytotoxicity.

    • Qin Cao
    • , Woo Shik Shin
    • , Henry Chan
    • , Celine K. Vuong
    • , Bethany Dubois
    • , Binsen Li
    • , Kevin A. Murray
    • , Michael R. Sawaya
    • , Juli Feigon
    • , Douglas L. Black
    • , David S. Eisenberg
    •  & Lin Jiang
  • Article |

    Chemically depolymerizing biomass polysaccharides to simple sugars is often controlled by the balance between depolymerization and degradation kinetics, which has limited the concentration of solutions that can be obtained and overall yields. The reversible stabilization of carbohydrates by acetal formation pushes back these limits and creates stabilized sugars that have advantageous properties for further upgrading.

    • Ydna M. Questell-Santiago
    • , Raquel Zambrano-Varela
    • , Masoud Talebi Amiri
    •  & Jeremy S. Luterbacher
  • Article |

    A direct conversion of carboxylic acids to alpha-olefins without the need for a stoichiometric additive has now been reported. The transformation is enabled by a dual cobalt/iridium proton-reduction–photoredox catalyst system, and can proceed on abundant fatty acids as well as on complex carboxylic acids.

    • Xiang Sun
    • , Junting Chen
    •  & Tobias Ritter
  • Article |

    A chemical proteomic strategy has now been developed for profiling pyridoxal-phosphate dependent enzymes (PLP-DEs) in cells. Pyridoxal-based probes are phosphorylated in situ and bind to cellular PLP-DEs as cofactor mimics. The method accessed 73% of the Staphylococcus aureus PLP-dependent proteome and annotated uncharacterized proteins as novel PLP-DEs.

    • Annabelle Hoegl
    • , Matthew B. Nodwell
    • , Volker C. Kirsch
    • , Nina C. Bach
    • , Martin Pfanzelt
    • , Matthias Stahl
    • , Sabine Schneider
    •  & Stephan A. Sieber
  • Article |

    MoS2 single layers spontaneously undergo a slow oxygen substitution reaction under ambient conditions giving rise to solid-solution-type 2D molybdenum oxy-sulfide crystals. The oxygen substitution sites of the 2D MoS2xOx crystals act as efficient single-atom catalytic centres for the hydrogen evolution reaction.

    • János Pető
    • , Tamás Ollár
    • , Péter Vancsó
    • , Zakhar I. Popov
    • , Gábor Zsolt Magda
    • , Gergely Dobrik
    • , Chanyong Hwang
    • , Pavel B. Sorokin
    •  & Levente Tapasztó
  • Article |

    Binding interactions, whether between a biological receptor and ligand or between a synthetic host and guest, are frequently stronger for larger molecules than for smaller ones. This is commonly believed to arise from increased dispersion interactions, but it has now been shown that cavitation energies—always required to dissolve molecules in solution—can be more important.

    • Suhang He
    • , Frank Biedermann
    • , Nina Vankova
    • , Lyuben Zhechkov
    • , Thomas Heine
    • , Roy E. Hoffman
    • , Alfonso De Simone
    • , Timothy T. Duignan
    •  & Werner M. Nau
  • Article |

    A series of in vitro and in vivo studies has now shown that 5fC is linked to increased nucleosome occupancy and stability. Moreover, there is evidence that Schiff base formation between histones and 5fC impacts RNA polymerase II transcription activity in mouse embryonic stem cells.

    • Eun-Ang Raiber
    • , Guillem Portella
    • , Sergio Martínez Cuesta
    • , Robyn Hardisty
    • , Pierre Murat
    • , Zhe Li
    • , Mario Iurlaro
    • , Wendy Dean
    • , Julia Spindel
    • , Dario Beraldi
    • , Zheng Liu
    • , Mark A. Dawson
    • , Wolf Reik
    •  & Shankar Balasubramanian

Amendments & Corrections

In Your Element

  • In Your Element |

    Stuart Cantrill explains why looking to the heavens for element 61 — named after the Titan who stole fire from the gods — could extend the periodic table.

    • Stuart Cantrill