Synthesis, crystal structure, and electronic structure of Li₂PbSiS₄: a quaternary thio­silicate with a compressed chalcopyrite-like structure

The new quaternary thio­silicate, Li₂PbSiS₄ (dilithium lead silicon tetra­sulfide), crystallizes in the noncentrosymmetric stannite structure type and belongs to a large family of severely compressed chalcopyrite-like compounds. The structure features a relatively regular SiS₄ tetra­hedron, a flattened LiS₄ tetra­hedron, and a distorted PbS₈ dodeca­hedron. Electronic structure calculations using density functional theory indicate that the yellow compound is an indirect bandgap semiconductor.

The influence of the type of halogen substituent and its position on the mol­ecular conformation, inter­molecular inter­actions and crystal packing for a series of 1-benzoyl-3-(halogenophen­yl)thio­ureas

Five new 1-benzoyl-3-(halogenophen­yl)thio­ureas have been synthesized and characterized. Hydrogen bonding, mol­ecular conformations and inter­molecular inter­actions have been examined in detail. The structures are described in com­parison to related previously described 1-benzoyl­thio­ureas.

Conformational polymorphs of 3-cyclo­propyl-5-(3-methyl-[1,2,4]triazolo[4,3-a]pyridin-7-yl)-1,2,4-oxa­diazole

Two conformational polymorphic structures of dipharmacophore 3-cyclo­propyl-5-(3-methyl-[1,2,4]triazolo[4,3-a]pyridin-7-yl)-1,2,4-oxa­diazole have been studied in detail using both X-ray diffraction and quantum chemical calculations. Stacking inter­actions of different types are strongest in the two crystals. In addition, the polymorphic structures differ with regard to the type of main structural motif of the crystal packing, which is a double column in the monoclinic structure and a single column in the ortho­rhom­bic structure.

Syntheses and structures of three macrocyclic supra­molecular com­plexes and one Zn^II-containing coordination polymer generated from a semi-rigid multidentate N-containing ligand

The semirigid organic ligand 4-{2-[(pyridin-3-yl)meth­yl]-2H-tetra­zol-5-yl}pyridine, with tetra­zole and pyridine fragments, has been used successfully to prepare coordination com­plexes with Zn^II salts. The ligand displays different conformations during the process of constructing coordination com­plexes. The results indicate that the selection of different counter-anions and different solvents plays an important role in the construction of various coordination com­plexes and has an important effect on the fluorescence properties through the hydrogen-bonding system and weak C—Cl⋯π or π–π inter­actions.

Polymorphism of methyl 4-amino-3-phenyl­iso­thia­zole-5-car­box­ylate: an experimental and theoretical study

Methyl 4-amino-3-phenyl­iso­thia­zole-5-car­box­yl­ate, being a close analogue of amflutizole, was used to study the capability of iso­thia­zole to form polymorphic structures. The application of experimental methods and quantum chemical calculations allowed an indication of the differences in the crystal packing of the noncentrosymmetric structure obtained due to faster crystallization and the centrosymmetric structure formed due to slower crystallization from a denser solvent.

Tri­thio­cyanuric acid: novel cocrystals and analysis of its tautomeric forms

The structures of two cocrystals of tri­thio­cyanuric acid with 2,2′-bipyridyl and 4-methyl­benzohydrazide have been determined. In the crystalline state, the mol­ecular com­ponents are linked by N—H⋯S hydrogen bonds, forming (8) synthons. The observed tautomerism of tri­thio­cyanuric acid was characterized by quantum chemistry methods.

Two-step crystal–crystal phase transformation of N-salicyl­idene-p-amino­benzoic acid by gas–solid reaction with aqua–ammonia vapour

N-Salicyl­idene-p-amino­benzoic acid crystals undergo a two-step gas–solid reaction with aqua–ammonia vapour in the crystalline state. Moreover, the photochromic behaviour of the crystals was switched from OFF to ON and back to OFF through a phase transformation.