In this issue, L. Dell’Amico et al. review mechanisms and synthetic strategies in visible-light-driven [2+2]-heterocycloadditions, and M. Kumar et al. discuss the visualization of dynamic nanostructures within supramolecular systems chemistry. The Minireviews deal with halide chemistry in tin perovskite optoelectronics (S. A. Haque et al.) as well as emerging materials for interfacial solar-driven water purification (C. Li et al.). X. Yang and G. Wu highlight work on single platinum atom catalysts with high density. In a Correspondence, N. G. White et al. point to structural motion in a hydrogen-bonded organic framework previously reported by T. Ben et al., who reply that the water confined therein can be regarded as a molecular superfluid.

In the original research section, B. M. Goodson et al. describe anomalously large antiphase signals from hyperpolarized orthohydrogen with a metal–organic-framework-based SABRE catalyst. J. Rieger et al. found that unimer exchange is not necessary for morphological transitions in polymerization-induced self-assembly. D. Leonori et al. succeeded in olefin dihydroxylation with nitroarenes as photoresponsive oxidants. I. Krossing et al. present low-valent M_xAl₃ cluster salts with tetrahedral [SiAl₃]⁺ and trigonal-bipyramidal [M₂Al₃]²⁺ cores (M: Si, Ge; see picture).

• Angewandte Chemie 8/2023: Necessary Exchange,
  Angew. Chem. Int. Ed. 2023, 62 (8).