Crystalline transformers: more within than meets the eye

Single-crystal diffraction studies yield information on the complex motions involved in phase transitions in molecular crystals. There is reason to believe that extensive potential exists for further discovery in this field.

The puzzling structure of Cu₅FeS₄ (bornite) at low temperature

Several studies have focused on the positions of cations in bornite; however there is still a lack of definitive proof on the ordering of iron. Comparison between high-resolution diffraction data and EXAFS strongly suggests that the preferred location of iron is on two specific sites. Moreover, the high-resolution X-ray powder diffraction revealed that a low-temperature first transition occurs towards a even more puzzling structure, studied on the basis of the room-temperature structure.

Azulene revisited: solid-state structure, invariom modeling and lattice-energy minimization of a classical example of disorder

Azulene, the classical example of a disordered structure, is revisited. Aspherical-atom least-squares refinement of high-resolution diffraction data is complemented with lattice-energy computations of model structures.

Tri­ethylphosphine as a molecular gear — phase transitions in ferrocenyl–acetylide–gold(I)

A sequence of single-crystal-to-single-crystal phase transitions has been observed at low temperature for a ferrocenyl–acetylide–gold(I) complex with triethylphosphine. These phase transitions involve almost uniquely the conformational change of triethylphosphine – a gear-like rotation around the P—Au axis. The changes are sequential, occurring in well separated layers within the crystal lattice and result in a noticeable contraction of the crystal cell volume.

Inflexible stoichiometry in bulk pyrite FeS₂ as viewed by in situ and high-resolution X-ray diffraction

The stoichiometry of iron pyrite, FeS₂, is rigorously studied using high-resolution and in situ X-ray diffraction. The upper bound on the concentration of sulfur vacancies in FeS₂ is investigated.

Determination of the miscibility gap in the solid solutions series of methyl­ammonium lead iodide/chloride

The determination of the miscibility gap and of the maximum degree of Cl substitution in the hybrid perovskite solid solution series CH₃NH₃Pb(I,Cl)₃, relevant for photovoltaic applications, based on high-resolution synchrotron powder X-ray data, is presented

Crystal packing control of a tri­fluoro­methyl-substituted furan/phenylene co-oligomer

Trifluoromethyl substituents control the crystal packing and optical properties of a furan/phenylene co-oligomer. All obtained crystals are highly emissive; however, their photophysical properties strongly depend on the crystal packing.

Melting point, molecular symmetry and aggregation of tetra­chloro­benzene isomers: the role of halogen bonding

The melting behaviour of tetra­chloro­benzene isomers is mainly associated with the nature of Cl⋯Cl halogen bonds. The significance of these interactions was confirmed by Hirshfeld surface analysis and quantum mechanical calculations showing correlations with the molecular symmetry.