To broaden the community and encourage researchers to use photocrystallographic methods, review articles, such as that of Hatcher et al. [(2024). Acta Cryst. C80, 585–600], showing the fundamentals of the approaches, most significant examples of such studies, but also guiding the reader through various stages of sample preparation and experiment planning, are very much needed.

Communications Chemistry, Published online: 28 November 2025; doi:10.1038/s42004-025-01769-8Metal–organic crystals with dynamic behaviours like bending and jumping offer promise in applications such as smart devices and flexible electronics. Here, the authors develop a Zn-based crystal exhibiting photomechanical effects under UV light, revealing insights into its structural transformation and mechanical properties.

The first three articles of the new `Best practice in crystallography' series have been published covering a guide to growing crystals for single-crystal diffraction studies, a guide to performing photocrystallography and a review detailing what aspects of crystal structure are of particular importance to determining electrical conductance in organic materials.

We report the photogeneration and characterization of an open-shell, terminal iron nitrido (EmL)Fe(N) using a sterically encumbered dipyrrin ligand environment. The Fe–N distance in the solid-state, zero-field 57Fe Mössbauer spectrum, and computational analysis are consistent with a triplet electronic ground state of the iron nitrido. Notably, the attenuation of Fe–N multiple bond character through occupying π*Fe–N enables (i) primary C(sp3)–H amination, (ii) H2 cleavage, (iii) aromatic C–C cleavage, and (iv) photocatalytic N-atom transfer reactivity. These modes of reactivity have not previously been observed in low-spin Fe(N) analogues.

Photoinduced linkage isomers (PLIs) of NO and NO2− are selectively generated by an appropriate choice of irradiation wavelength at low temperature within the same molecular complex [Rh(NO)(NO2)2(But2PH)2]. The structures of the PLIs are characterised by photocrystallography and the corresponding vibrational

arXiv abstract link

Expanding the boundaries of synthetic tractability ─ of what molecules can be synthesized and isolated ─ is an eternal challenge for synthetic chemists. The development of new synthetic methods and strategies enables the properties and potential functions of novel molecular targets to be experimentally evaluated. In the context of catalysis, predictable synthetic strategies are often available to access kinetically persistent intermediates such as catalyst resting states. In contrast, synthesis and characterization of the reactive intermediates are often not possible due to the fleeting lifetimes of these species. In crystallo photochemistry combines single-crystal matrix isolation with cryogenic photochemistry to enable reactive intermediates to be synthesized under conditions in which they are persistent and can be (crystallographically) characterized. This Outlook highlights key achievements of in crystallo photochemistry as well as discusses opportunities and challenges that confront realization of the potential of in crystallo synthesis to redefine the boundaries of synthetic tractability.