In this issue, I. Willner et al. review principles and applications of DNA switches. How can drug delivery, opening/closure of pores, and switchable catalysis be enabled? In a Minireview, D. Leonori and V. K. Aggarwal discuss stereospecific couplings of secondary and tertiary boronic esters. The Highlight deals with the range of oxidation states of iridium (P. Pyykkö and W.-H. Xu).

In the Communications section, D. C. Johnson et al. describe how the synthesis of inorganic structural isomers can be achieved by diffusion-constrained self-assembly of designed precursors (see picture). C. Poriel et al. report on derivatives of dihydroindenofluorene isomers as host materials for phosphorescent OLEDs. K. Tomooka et al. present the concise synthesis, structural analysis, and reactions of heteratom-embedded medium-sized cycloalkynes.

• Angewandte Chemie 4/2015: Curiosity and Applications,
  Angew. Chem. Int. Ed. 2015, 54 (4).