In this issue, B. N. Bhawal and B. Morandi review catalytic isofunctional reactions. How has the repertoire of shuttle and metathesis reactions been expanded? The Minireviews deal with bent crystals (P. Naumov et al.) and polarization in photocatalysis (T. Ma et al.). S. Sproules comments on a recent Communication on the stabilization of low-valent iron(I) in a high-valent vanadium(V) oxide cluster by C. Streb et al., and the latter reply.

In the original research section, L.-B. Sun et al. report on the generation of hierarchical porosity in metal-organic frameworks by the modulation of cation valence (see picture). J. D. Keasling et al. present a high-throughput mass spectrometric enzyme activity assay, which has enabled the discovery of cytochrome P450 biocatalysts. R. A. Layfield et al. describe the synthesis, structure, and chemical bonding of uranocenium. Y. Morimoto et al. detail switching of the cyclization modes of polyepoxides in response to the acidity of the reaction solvent.

• Angewandte Chemie 30/2019: Expanding the Repertoire,
  Angew. Chem. Int. Ed. 2019, 58 (30).