In this issue, P. Melchiorre et al. review mechanisms in photocatalysis. How can the understanding of these reactions be improved? In his Guest Editorial, E. Reiser calls for a more holistic approach in photocatalysis. The Minireviews deal with confined nanopipette sensing (Y.-L. Ying et al.) and isolable silylene ligands to boost efficiency and selectivity in metal-mediated catalysis (Y.-P. Zhou and M. Driess). P. J. Ragogna et al. share a Viewpoint on antibacterial activity of polymers and the nature of amphiphilic balance, and D. E. Lewis contributes an Essay on the historic treatise of Butlerov and Markovnikov on the transformation from chemical structure to reaction regiochemistry.

In the Communications section, M.-H. Zeng et al. track the process of a solvothermal domino reaction that leads to a stable triheteroarylmethyl radical (see picture). M. C. Breadmore et al. succeeded in the in-transit electroextraction of small-molecule pharmaceuticals from blood. V. V. Rybkin et al. simulated the dynamics of the bulk hydrated electron from many-body wave-function theory, and H. F. Bettinger et al. investigated the superelectrophilicity of 1,2-azaborine and the formation of xenon and carbon monoxide adducts.

• Angewandte Chemie 12/2019: Understanding Reactions,
  Angew. Chem. Int. Ed. 2019, 58 (12).