In this issue, A. Greiner et al. review the use of low-density open cellular sponges as functional materials. What makes these sponges seem perfect? In a Minireview, Y. Fang and X. Wang discuss metal-free boron-containing heterogeneous catalysts. The Highlights deal with unsymmetrical biaryl compounds through metal- and reagent-free electrochemical couplings (H. J. Schäfer) and click chemistry in cell biology and drug discovery (M. Gehringer and S. A. Laufer).

In the Communications section, W. J. Smit and H. J. Bakker describe the surface of ice as supercooled water (see picture). N. J. Turner et al. found biocatalytic routes to enantiomerically enriched dibenz[c,e]azepines. M. Mazzanti et al. succeeded in the reduction of a cerium(III) siloxide to obtain a quadruple-decker arene-bridged cerium(II) sandwich complex.

• Angewandte Chemie 49/2017: Perfect Materials,
  Angew. Chem. Int. Ed. 2017, 56 (49).