November 2015 issue
The field of crystallography, which has had a major impact on the sciences in the last 100 years, is continuing to expand scientific horizons as technical and conceptual boundaries are overcome. Structure–function–dynamics will become an integrated theme for many studies as will obtaining structures without the `benevolent tyranny' of crystals.
An IUCrJ paper by Levine et al. highlights the promise and challenge of 3D X-ray structural microscopy as a unique tool to test predictive models of materials behavior.
In the solid-state photodimerization of cinnamic acid polymorphs, can mechanical properties tell us whether Schmidt `minimal molecular movement' or Kaupp `molecular migration' is more important?
Structure–mechanical property studies confirm that the extent of mechanochromic luminescence in crystalline organic fluorophores positively correlates with the extent of plasticity.
A new interference technique to measure the transverse coherence of X-ray free-electron lasers is proposed and applied to the characterization of the coherence properties of ultra-intense focused X-ray pulses from the SPring-8 Ångstrom Compact free-electron LAser (SACLA).
Analysis of serial femtosecond crystallography data collected at the Linac Coherent Light Source using two distinct photon fluxes shows different degrees of ionization of Gd atoms bound to a lysozyme protein, due to electronic damage processes. The charge contrast on the heavy atoms is quantified using difference Fourier maps, and the way in which this could be applied to phasing is discussed.
A ground breaking new capability for measuring complete strain and stress tensors nondestructively from deeply buried, sub-micrometre sample volumes within microstructurally complex and multicomponent specimens is presented. The method is demonstrated on technologically important copper through-Si vias that are used in advanced three-dimensional microelectronics.
To understand molecular recognition, one needs to characterize the conformational changes that take place when a free (unbound) molecule forms a complex with another protein. An analysis of 281 protein components is presented, delineating such changes in terms of accessible surface area, secondary structure, crystallographic B factors and disorder-to-order transitions.
A new monoclinic polymorph, form II, of 3,4-dimethoxycinnamic acid has been isolated and shows a different photochemical and photomechanical property from the previously reported triclinic form I. The solid-state 2 + 2 photodimerization of these polymorphs is rationalized on the basis of minimum and maximum molecular movement during the reaction – the so-called Kaupp and Schmidt models for these reactions.
A theoretical investigation is presented of how radiation damage gates X-ray laser diffraction from single isolated protein molecules. The impact of this effect on the feasibility of X-ray laser single-molecule imaging with pulse durations of the order of 10 fs is discussed.
Supramolecular interactions in the solid state are discussed in the context of crystal engineering. Specific topics include halogen bonding, ambient and non-ambient conditions, isostructurality and polymorphism, and kinetic assembly of coordination polymers.