IUCrJ on passing its tenth anniversary and entering its second decade: progress, current status and prospects for the future

This Editorial briefly celebrates the history and progress of IUCrJ in its first decade, reviews its present status, and suggests some pointers for the future.

Using high pressure to understand the behavior of organic molecular crystals

In the recent publication by Zhou et al. [(2025). IUCrJ, 12, 16–22], the crystal structure of benzo[a]pyrene was studied under high pressure up to 28 GPa using single-crystal X-ray diffraction and DFT calculations. This commentary highlights the importance of high pressure for analyzing organic molecular crystals.

Connecting lattice and molecular vibrations to organic crystal properties

Understanding dynamic processes in molecular crystals is becoming crucial for the development of next-generation smart crystalline materials. In this context, Zwolenik & Makal [(2025). IUCrJ, 12, 23–35] shed light on the complex dynamics–structure–properties relation of a pyrene derivative by correlating molecular and lattice anharmonic vibrations with the unusual thermal expansion of the compound.

FAIR data – the photon and neutron communities move together towards open science

The German project DAPHNE4NFDI together with the European Synchrotron and Free Electron Laser User Organization (ESUO), the European Neutron Scattering Association (ENSA), and European synchrotron and neutron facilities continue the development of FAIR data handling procedures laid out by the EU-funded projects PaNOSC and ExPaNDS. Written by members of these organizations, this `white paper' documents the current status of this discussion.

Structural transformations and stability of benzo[a]pyrene under high pressure

This study explores the high-pressure behavior of benzo[a]pyrene, revealing two previously unknown polymorphs at 4.8 and 7.1 GPa. These findings enhance our understanding of the structural dynamics and stability of polycyclic aromatic hydrocarbons under extreme conditions.

Tracking anharmonic oscillations in the structure of β-1,3-di­acetylpyrene

A recently discovered β polymorph of 1,3-diacetylpyrene has turned out to be a prominent negative thermal expansion material. Its unique properties can be linked to anharmonic oscillations in the crystal structure. The onset and development of anharmonic behavior have been successfully tracked over a wide temperature range by single-crystal X-ray diffraction experiments. Sufficient diffraction data quality combined with modern quantum crystallography tools allowed a thorough analysis of the elusive anharmonic effects for a moderate-scattering purely organic compound.

Exploiting fourth-generation synchrotron radiation for enzyme and photoreceptor characterization

(Time-resolved) macromolecular crystallography at the new ID29 beamline at the ESRF is described.

Structure of an ex vivo Drosophila TOM complex determined by single-particle cryoEM

A 3.3 Å resolution map and structural model of the TOM complex from Drosophila melanogaster were determined by single-particle cryoEM. The complex was extracted from native membranes of the fly retina following targeted expression of a Tom40 transgene.

Incommensurately modulated structure of Zn₄Si₂O₇(OH)₂·H₂O at high pressure

Refinement of the hemimorphite crystal structure using single-crystal synchrotron X-ray diffraction data collected at high pressure revealed a structural phase transition into an incommensurately modulated structure, accompanied by the appearance of satellite reflections.

Towards improved accuracy of Hirshfeld atom refinement with an alternative electron density partition

We demonstrate that applying the alternative electron density partition in a Hirshfeld atom refinement may significantly improve the accuracy of hydrogen atom parameters. The new partition leads to less overlapping atomic densities. As a result, hydrogen atom parameters are less dependent on the structural parameters of their neighbours and their inaccuracies.

Managing negative linear compressibility and thermal expansion through steric hindrance: a case study of 1,2-bis­(4′-pyridyl)­ethane cocrystals

The negative linear compressibility and negative thermal expansion behaviours of two isostructural 1:1 cocrystals of 1,2-bis­(4′-pyridyl)­ethane with fumaric and succinic acids were revealed and compared, showing surprisingly strong ramifications of a small steric hindrance on the magnitude of both effects.

Real-time data processing for serial crystallography experiments

We report the use of streaming data interfaces to process data in real time from serial crystallography experiments, with a latency of less than 1 s per frame and without requiring intermediate data storage on disk.

SCXRD, CSP-NMRX and microED in the quest for three elusive polymorphs of meloxicam

The case of three elusive polymorphs of meloxicam highlights the strengths and weaknesses of single-crystal X-ray diffraction, crystal structure prediction–NMR crystallography and microcrystal electron diffraction as crystal structure determination approaches. Each method was successful in solving only one of the polymorphs, showcasing the advantage of using the whole arsenal of available techniques.

Advancing dynamic quantum crystallography: enhanced models for accurate structures and thermodynamic properties

By implementing the aspherical atom model to normal mode refinement, we obtained accurate structures [including H-atom positions and anisotropic displacement parameters (ADPs)] and heat capacity from single-crystal X-ray diffraction data.