Volume 8 Issue 12, December 2016

Volume 8 Issue 12

Understanding the transport of charge across non-covalently bonded molecules is key to our understanding of many diverse systems, from oxidative damage and repair of DNA to the efficiency of organic electronic materials. Single-molecule break junctions are an important stage on which to test and develop this understanding and they have now been used by Ferdinand C. Grozema, Herre S. J. van der Zant and colleagues to show that electronic transport through a π-stacked dimer can be precisely controlled by mechanically manipulating its conformation and thus turning destructive interference effects ON or OFF. The cover shows the electrodes of a break junction connected by a π-stacked dimer, the molecular orbitals of which are also shown.Article p1099IMAGE: NICOLAS RENAUD, DELFT UNIVERSITY OF TECHNOLOGY

News and Views

  • News & Views |

    Despite their potential as drugs, peptides are generally not cell permeable, which limits their practical applications in medicine. Now, linear peptides have been cyclized by using a heteroaromatic linker. This cyclization both improves passive membrane permeability and stabilizes a biologically relevant secondary structure.

    • Fumito Saito
    •  & Jeffrey W. Bode
  • News & Views |

    Three different methods that use a single ruthenium catalyst to enable the facile formation of meta- and para-substituted alkenylarenes have now been developed. The reactions proceed through a tandem alkenylation/decarboxylation process and provide several advantages over alternative approaches.

    • Marco Simonetti
    •  & Igor Larrosa
  • News & Views |

    The targeted release of bioactive molecules to diseased tissues has the potential to improve therapeutic efficacy, but not all drugs contain a free functional group that can be easily attached to an antibody. Now, a linker technology has been developed to enable the traceless release of tertiary and heteroaryl amine-containing drugs.

    • Tiago Rodrigues
    •  & Gonçalo J. L. Bernardes

Perspective

  • Perspective |

    No longer a theoretical dream, this Perspective describes effects of oriented external electric fields on rates and selectivity patterns of nonpolar reactions. Discussions of the Diels–Alder reaction, C–H and C=C bond activations and so on, underscore the potential usage of oriented electric fields as future smart catalysts, inhibitors and reagents in chemistry.

    • Sason Shaik
    • , Debasish Mandal
    •  & Rajeev Ramanan

Articles

  • Article |

    Single-molecule junctions provide a unique platform to understand how molecular structure affects electronic transport. Now it has been shown that electronic transport through a π-stacked dimer can be precisely controlled when pulling it apart. This behaviour is caused by quantum interference effects that are turned ON or OFF depending on dimer conformation.

    • Riccardo Frisenda
    • , Vera A. E. C. Janssen
    • , Ferdinand C. Grozema
    • , Herre S. J. van der Zant
    •  & Nicolas Renaud
  • Article |

    Controlling macrocycle conformation represents a powerful tool for the construction of new bioactive molecules. Now, peptide-based macrocycles bearing a 1,3,4-oxadiazole moiety grafted into their backbone have been synthesized via a new cyclization approach. The resulting cyclic products exhibit conformationally rigid turn structures (stabilized through intramolecular hydrogen bonding) that can display passive membrane permeability.

    • John R. Frost
    • , Conor C. G. Scully
    •  & Andrei K. Yudin
  • Article |

    Many drugs contain tertiary and heteroaryl amines; however, these functional groups are difficult to reversibly crosslink to a carrier protein. Now, a method for conjugating anticancer and antibiotic drugs to antibodies via a quaternary ammonium salt has been developed. Cleavage of the linker results in the traceless release of the free drug and subsequent therapeutic activity.

    • Leanna R. Staben
    • , Stefan G. Koenig
    • , Sophie M. Lehar
    • , Richard Vandlen
    • , Donglu Zhang
    • , Josefa Chuh
    • , Shang-Fan Yu
    • , Carl Ng
    • , Jun Guo
    • , Yanzhou Liu
    • , Aimee Fourie-O'Donohue
    • , MaryAnn Go
    • , Xin Linghu
    • , Nathaniel L. Segraves
    • , Tao Wang
    • , Jinhua Chen
    • , BinQing Wei
    • , Gail D. Lewis Phillips
    • , Keyang Xu
    • , Katherine R. Kozak
    • , Sanjeev Mariathasan
    • , John A. Flygare
    •  & Thomas H. Pillow
  • Article |

    Singlet fission in assemblies of molecular chromophores offers a promising route to improving solar cell efficiencies, but its mechanism is not fully understood. Now, a series of covalently bound π-stacked terrylenediimide dimers have been studied to elucidate the role of interchromophore charge-transfer states in the mechanism of singlet fission.

    • Eric A. Margulies
    • , Claire E. Miller
    • , Yilei Wu
    • , Lin Ma
    • , George C. Schatz
    • , Ryan M. Young
    •  & Michael R. Wasielewski
  • Article |

    Pharmaceutical compound libraries are an essential part of drug discovery and the screening of libraries for new drug leads is routine. It has now been shown that these heterocycle-rich, diverse libraries can also be used for ligand discovery. The discovery and application of several new ligands to nickel-catalysed cross-electrophile coupling is demonstrated.

    • Eric C. Hansen
    • , Dylan J. Pedro
    • , Alexander C. Wotal
    • , Nicholas J. Gower
    • , Jade D. Nelson
    • , Stephane Caron
    •  & Daniel J. Weix
  • Article |

    Hampered by a lack of practical syntheses, benzazetidines are one of the few rarely explored compounds in N-heterocyclic chemical space. An efficient synthesis of various benzazetidines by Pd-catalysed intramolecular C−H amination of N-benzyl picolinamides is now reported. Reagent-controlled reductive elimination of a Pd intermediate is a key aspect of this particular method.

    • Gang He
    • , Gang Lu
    • , Zhengwei Guo
    • , Peng Liu
    •  & Gong Chen
  • Article |

    Difficulties in experimentally achieving simultaneous structural sensitivity and time resolution have hindered the real-time mapping of the vibrational energy relaxation pathways in biomacromolecules. Now, using ultrashort light pulses to locally deposit excess energy in a protein-bound haem, the temporal evolution of the subsequent energy flow has been monitored, unravelling vibrational couplings that lead to mode-specific temperature changes.

    • C. Ferrante
    • , E. Pontecorvo
    • , G. Cerullo
    • , M. H. Vos
    •  & T. Scopigno
  • Article |

    Achieving high regioselectivity in hydroarylation of alkynes has been a long-standing challenge. Now, a ruthenium-catalysed decarboxylative alkyne hydroarylation with broad substrate scope, high chemo- and stereoselectivity, as well as controlled and versatile regiochemistry, is described.

    • Jing Zhang
    • , Ruja Shrestha
    • , John F. Hartwig
    •  & Pinjing Zhao
  • Article |

    Off-target drug binding of anti-HIV protease inhibitors to a zinc metalloprotease has been suspected for some time. Now, mass spectrometry of human zinc metalloprotease ZMPSTE24 in the presence of four inhibitors has provided molecular evidence for this off-target binding. These results also enabled an investigation of the effects of the inhibitors on the processing of farnesylated prelamin A peptides.

    • Shahid Mehmood
    • , Julien Marcoux
    • , Joseph Gault
    • , Andrew Quigley
    • , Susan Michaelis
    • , Stephen G. Young
    • , Elisabeth P. Carpenter
    •  & Carol V. Robinson
  • Article |

    The selective formation of Markovnikov products in carbonylation reactions is a challenging problem, especially from unactivated substrates. Now, a highly Markovnikov-selective alkoxycarbonylation reaction is described using a catalyst system based on palladium and the cataCXium ligand POMeCy(Ph). The resulting branched carboxylates are important structural components in many flavour and fragrance products.

    • Haoquan Li
    • , Kaiwu Dong
    • , Haijun Jiao
    • , Helfried Neumann
    • , Ralf Jackstell
    •  & Matthias Beller

In Your Element

  • In Your Element |

    Discovered during secret testing by the United States, Joanne Redfern tells us about element 99 and why its namesake cautioned against the very technology that led to its creation.

    • Joanne Redfern