Short strong hydrogen bonds in multi-component organic acid molecular crystals exhibit temperature dependent proton migration for certain HB donor–acceptor distances.

The known complex [Ni(medpt)(η

X-ray photoelectron spectroscopy (XPS) has emerged as a technique that allows for characterization and classification of hydrogen bonding and proton transfer interactions in organic crystal structures, in a way that is complementary to crystallography by X-ray or neutron diffraction. Here, we analyze the nitrogen 1s core-level binding energies (BEs) of isonicotinamide (IN) systems with proton transfer between donor and acceptor groups at short distances. We show how a careful calibration of the BE scale places these salt systems correctly on the edge of the so-called salt–cocrystal continuum. We show how performing a fitting analysis of the data that is consistent with elemental analysis, expected stoichiometry, and quantification of adventitious carbon contamination facilitates the determination of absolute BEs with accuracy and reproducibility within ±0.1 eV. The determined N 1s core-level BEs of the protonated IN acceptors suggest that the local geometric arrangements of the donor, acceptor, and proton can influence the N 1s core-level BE significantly.

Herein, we describe the development of a novel dual air-bearing fixed-χ diffractometer for beamline I19 at Diamond Light Source. The diffractometer is designed to facilitate the rapid data collections possible with a Dectris Pilatus 2M pixel-array photon-counting detector, while allowing remote operation in conjunction with a robotic sample changer. The sphere-of-confusion is made as small as practicably possible, through the use of air-bearings for both the ω and ϕ axes. The design and construction of the new instrument is described in detail and an accompanying paper by Johnson et al. (also in this issue) will provide a user perspective of its operation.

We report a series of six isoreticular metal–organic frameworks (MOFs) for selective gas adsorption, specifically for selective adsorption of CO2 and C2H2.

It is important to be able to identify the precise position of H-atoms in hydrogen bonding interactions to fully understand the effects on the structure and properties of organic crystals. Using a combination of near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and density functional theory (DFT) quantum chemistry calculations, we demonstrate the sensitivity of core-level X-ray spectroscopy to the precise H-atom position within a donor-proton-acceptor system. Exploiting this sensitivity, we then combine the predictive power of DFT with the experimental NEXAFS, confirming the H-atom position identified using single-crystal X-ray diffraction (XRD) techniques more easily than using other H-atom sensitive techniques, such as neutron diffraction. This proof of principle experiment confirms the H-atom positions in structures obtained from XRD, providing evidence for the potential use of NEXAFS as a more accurate and easier method of locating H-atoms within organic crystals.

Abstract. We present preliminary structural results of the non-structural protein 3 (nsP3) macro domain from the Mayaro virus (MAYV), an emerging virus of South American tropic regions, by means of synchrotron X-ray powder diffraction. Indexing of the diffraction patterns indicate a trigonal/hexagonal lattice (a ¼ 61:60 A, c ¼ 94:61 A), analogous to the known lattice of the sequence homologous nsP3 macro domain from the Chikungunia virus (CHIKV), though MAYV must have looser molecular packing: the cell dimensions of MAYV are significantly altered in comparison to CHIKV and the unit cell comprises 6 molecules and 58% solvent. The results are discussed in terms of their methodological and biological importance.

Mapped electron density and ab initio modelling reveal how H-atom position and molecular environment tune short hydrogen bond characteristics and properties.