Foreword to the special issue Crystallography in Latin America: a vibrant community

This collection highlights the diversity and quality of research conducted by Latin American scientists, and emphasizes the interdisciplinary nature of crystallography, highlighting its connections with other research fields and presenting innovative and thought-provoking studies.

Fast event-based electron counting for small-mol­ecule structure determination by MicroED

Fast readout event-based electron counting (EBEC) is a promising detection strategy to determine accurate ab initio structures of beam-sensitive small mol­ecules by MicroED. A fast EBEC approach enhances the dynamic range of MicroED data by limiting the likelihood of coincidence loss (CL) – the undercounting of electrons due to their spatially and temporally unresolved arrival on a direct electron detector. As implemented by new counting detectors, fast EBEC allows structure-worthy data sets to be captured from individual small-mol­ecule crystals in under a minute.

Magnesium and potassium scorpionate com­plexes based on di­hydro­bis­(pyrazol­yl)borate

Analysis of the crystal structure of [di­hydro­bis­(pyrazol-1-yl)borato]tris­(tetra­hydro­furan)magnesium(II) tetra­benzyl­borate reveals a pronounced boat-shaped central Mg(N–N)₂B moiety with a weak pseudo-axial B—H⋯Mg inter­action. A novel counter-ion, [B(C₇H₇)₄)]⁻, has been obtained by the reaction between KBH₄ and (PhCH₂)MgCl to produce a polymeric potassium tetra­benzyl­borate with predominant (η⁶-C₆H₅)⋯K and (η³-C₆H₅)⋯K inter­actions.

Two nonlinear optically responsive crown ether inclusion com­pounds based on a sulfonimide anion assembly

Two novel benzyl­amine-based crown ether inclusion com­plexes have been synthesized and they exhibit nonlinear optical properties. Notably, [(C₆H₅–CH₂–NH₃)(18-crown-6)][TfNMs] [TfNMs = methyl­sulfon­yl)(tri­fluoro­meth­ylsulfon­yl)azanide] represents the first example of an 18-crown-6 com­plex with TfNMs as the counter-ion, enriching the family of crown ether inclusion com­plexes.

Rb₂Ca₂Si₂O₇: a new alkali alkaline-earth silicate based on [Si₂O₇]⁶⁻ anions

The crystal structure and thermal expansion of Rb₂Ca₂Si₂O₇ have been investigated from single-crystal diffraction data. The structural relationships with other pyrosilicates are discussed.

Synthesis, crystal structure elucidation, theoretical characterization and thermochemistry analysis of the potential anti­cancer drug BFS

A new crystal structure of the fluorine analogue of busulfan was ob­tained and analyzed using single-crystal X-ray diffraction and various com­putational methods. The crystal structure is stabilized by, among other factors, hy­dro­gen bonds, as confirmed by density functional theory calculations.

Synthesis and crystal structure of a nickel(II) 2′-de­oxy-6-thio­guanosine nitrate com­plex

The cationic tris-com­plex [Ni^II(d-tG)₃]²⁺ features bidentate N,S-chelating ligands in a distorted fac-S₃N₃ octa­hedral geometry with one Δ and two Λ isomers observed in the three independent cations, each with crystallographic threefold rotation symmetry.

Synthesis and characterization of coumarin-derived sulfur analogues using Lawesson's reagent

The synthesis and characterization of six novel coumarin derivatives containing O and S atoms are described. Hirshfeld surface and energy framework analyses show that stacked π–π ring inter­actions occur for all the structures and various hy­dro­gen-bond inter­actions link the stacks to form three-dimensional energy frameworks.