Classroom experiments with artificial sweeteners: growing single crystals and simple calorimetry

An easily accessible experimental set-up to grow large single crystals of two sweeteners readily available in supermarkets, erythritol and xylitol, is described. The crystallization of these compounds illustrates the principles of crystallization by evaporation·The crystal-growing experiment is complemented with a simple calorimetric set-up to demonstrate the endothermic nature of the dissolution of the selected sweeteners in a more qu­anti­tative approach by measuring the heat of dissolution.

Crystal structure and Hirshfeld surface analysis of ethyl (3E)-5-(4-fluoro­phen­yl)3-{[(4-meth­oxy­phen­yl)formamido]­imino}-7-methyl-2H,3H,5H-[1,3]thia­zolo[3,2-a]pyrimidine-6-carboxyl­ate 0.25-hydrate

The di­hydro­pyrimidine ring in the title mol­ecule is distinctly non-planar. In the crystal, zigzag chains parallel to [010] are formed by N—H⋯N hydrogen bonds and are connected into layers parallel to (100) by O—H⋯O, O—H⋯F, C—H⋯O, C—H⋯F and C—H⋯N hydrogen bonds. Further C—H⋯O hydrogen bonds connect the layers.

Crystal structure, Hirshfeld surface analysis and DFT calculations of 7-bromo-2,3-di­hydro­pyrrolo[2,1-b]quinazolin-9(1H)-one

The crystal structure of the title compound has been characterized by single-crystal X-ray diffraction and Hirshfeld surface analyses. The mol­ecular structure and frontier orbitals were also investigated using DFT.

Synthesis, X-ray diffraction study, analysis of inter­molecular inter­actions and mol­ecular docking of ethyl 1-(3-tosyl­quinolin-4-yl)piperidine-4-carboxyl­ate

An easy synthetic route towards ethyl 1-(3-tosyl­quinolin-4-yl)piperidine-4-carboxyl­ate was found. Its mol­ecular and crystal structures are described as well and the biological activity is also predicted using mol­ecular docking studies.

Crystal structure of 4,4′-(diazenediyl)dipyridinium nitrate perchlorate

The title compound was obtained unexpectedly by the reaction of Co(ClO₄)₂·6H₂O and cytidine-5′-monophosphate with 4,4′-azo­pyridine in an aqueous solution of nitric acid. In the crystal, N—H⋯O hydrogen bonds between dications and anions lead to the formation of chains.

Crystal structure, Hirshfeld surface analysis and geometry optimization of 2-hy­droxy­imino-N-[1-(pyrazin-2-yl)ethyl­idene]propano­hydrazide

The title compound, 2-hy­droxy­imino-N-[1-(2-pyrazin­yl)ethyl­idene]propane­hydrazide, is a ligand able to form polynuclear metal complexes. The mol­ecule is not planar due to a twist between the oxime and amide groups. In the crystal, mol­ecules are linked by O—H⋯O hydrogen bonds into supra­molecular chains.

Effect of methyl­ene versus ethyl­ene linkers on structural properties of tert-butyl and mesityl bis­(imidazolium) bromide salts

The crystal structures of ligand precursor bis­(imidaozolium) salts 1,1′-methyl­enebis(3-tert-butyl­imidazolium) dibromide monohydrate, C₁₅H₂₆N₄⁺·2Br⁻·H₂O or [^tBuNHC₂Me][Br]₂·H₂O, 1,1′-(ethane-1,2-di­yl)bis­(3-tert-butyl­imidazolium) dibromide dihydrate, C₁₆H₂₈N₄⁺·2Br⁻·2H₂O or [^tBuNHC₂Et][Br]₂·2H₂O, 1,1′-methyl­enebis[3-(2,4,6-tri­methyl­phen­yl)imidazolium] dibromide dihydrate, C₂₅H₃₀N₄²⁺·2Br⁻·2H₂O or [^MesNHC₂Me][Br]₂·2H₂O, and 1,1′-1,1′-(ethane-1,2-di­yl)bis­[3-(2,4,6-tri­methyl­phen­yl)imidazolium] dibromide tetra­hydrate, C₂₆H₃₂N₄²⁺·2Br⁻·4H₂O or [^MesNHC₂Et][Br]₂·4H₂O, are reported. At 293 K, [^tBuNHC₂Me][Br]₂·H₂O crystallizes in the P2₁/c space group, while [^tBuNHC₂Et][Br]₂·2H₂O crystallizes in the P2₁/n space group at 100 K. At 112 K, [^MesNHC₂Me][Br]₂·2H₂O crystallizes in the ortho­rhom­bic space group Pccn while [^MesNHC₂Et][Br]₂·4H₂O crystallizes in the P2₁/c space group at 100 K.

Crystal structures of the Lewis acid–base adducts {[(C₆H₁₁)₂N]₃Ti–LB}⁺[MeB(C₆F₅)₃]⁻·1.5C₇H₈; LB = (C₆H₅)₃PO (1), p-F—C₆H₄CN (2)

In the mol­ecular structures of the two title compounds, the central titanium(IV) atoms are coordinated in a distorted tetra­hedral fashion. Thereby, the titanium atom is stabilized by the Lewis bases tri­phenyl­phosphine oxide (1) and p-fluoro­benzo­nitrile (pFBN) (2) with dative O—Ti and N—Ti bonds, respectively.

Synthesis and crystal structure of ebastinium hydrogen fumarate

Crystals of the title salt are twinned by pseudo-merohedry and the structure shows extensive disorder. A strong N—H⋯O hydrogen bond links the cation and the anion and the anions are linked into [010] chains by O—H⋯O hydrogen bonds.

Crystal structure and Hirshfeld surface analysis of N-(2,6-di­methyl­phen­yl)-2-[3-hy­droxy-2-oxo-3-(2-oxoprop­yl)indolin-1-yl]acetamide

The cup-shaped conformation of the title mol­ecule is largely determined by an intra­molecular N—H⋯O hydrogen bond. In the crystal, double layers of mol­ecules are formed by O—H⋯O and C—H⋯O hydrogen bonds.

Crystal structure of an indium–salicyl­hydroximate complex cation: [In₄(H₂shi)₈(H₂O)₆](NO₃)₄·8.57H₂O

The title compound [In₄(H₂shi)₈(H₂O)₆](NO₃)₄·8.57H₂O·solvent, where H₂shi⁻ is salicyl­hydroximate, is a dimer of two [In₂(H₂shi)₄(H₂O)₃]²⁺ units that are related by an inversion center. The overall configuration of the dimer has a step-like topology, and each In^III ion is seven coordinate with a penta­gonal–bipyramidal geometry.

Crystal structure and Hirshfeld surface analysis of 4-(3-meth­oxy­phen­yl)-2,6-di­phenyl­pyridine

The title compound was obtained via the reaction of (1E,2E)-3-(3-meth­oxy­phen­yl)-1-phenyl­prop-2-en-1-one with ethyl 2-oxo­propano­ate, using NH₄I as a catalyst. In the mol­ecule, the four rings are not in the same plane, the pyridine ring being inclined to the benzene rings by 17.26 (6), 56.16 (3) and 24.50 (6)°. In the crystal, mol­ecules are linked by C—H⋯π inter­actions into a three-dimensional network.

Crystal structure of N-butyl-2,3-bis­(di­cyclo­hexyl­amino)­cyclo­propeniminium chloride benzene monosolvate

The structure of the acid chloride salt of the superbase N-butyl-2,3-bis­(di­cyclo­hexyl­amino)­cyclo­propenimine is reported.

Crystal structure and Hirshfeld surface analysis of ethyl 2′-amino-5-bromo-3′-cyano-6′-methyl-2-oxo­spiro­[indoline-3,4′-pyran]-5′-carboxyl­ate

In the title structure, the 2,3-di­hydro-1H-indole ring system is nearly planar, while the conformation of the 4H-pyran ring is close to a flattened boat. The mean planes of these fragments are approximately perpendicular to each other. In the crystal, the mol­ecules are connected into layers by N—H⋯N and N—H⋯O hydrogen bonds.

Syntheses and crystal structures of 4-(4-meth­oxy­phen­yl)piperazin-1-ium 4-methyl­benzoate monohydrate and bis­[4-(4-meth­oxy­phen­yl)piperazin-1-ium] benzene-1,2-di­carboxyl­ate

Two salts derived from N-(4-meth­oxy­phen­yl)piperazine crystallize with six independent mol­ecular species in the asymmetric unit. In each compound, multiple hydrogen bonds link these components into complex sheets.

Crystal structure determination, Hirshfeld surface, crystal void, inter­molecular inter­action energy analyses, as well as DFT and energy framework calculations of 2-(4-oxo-4,5-di­hydro-1H-pyra­zolo[3,4-d]pyrimidin-1-yl)acetic acid

The bicyclic ring system is planar with the carb­oxy­methyl group rotated out of this plane by 81.05 (5)°. In the crystal, corrugated layers are generated by N—H⋯O, O—H⋯N and C—H⋯O hydrogen-bonding inter­actions. The layers are associated through additional C—H⋯π(ring) inter­actions.

Crystal structures of two new divalent transition-metal salts of carb­oxy­benzene­sulfonate anions

The structure of hexa­aqua­nickel(II) bis­(3-carb­oxy-4-hy­droxy­benzene­sulfonate) dihydrate consists of alternating layers of inorganic cations and organic anions linked by O—H⋯O hydrogen bonds that also include non-coordinated water mol­ecules of crystallization. The structure of hexa­aqua­cobalt(II) bis­(3-carb­oxy­benzene­sulfonate) dihydrate is also built of alternating layers of complex cations and organic anions without direct coordination to the metal by the protonated carboxyl­ate or unprotonated sulfonate groups. A robust O—H⋯O hydrogen-bonding network involving primarily the coordinated and non-coordinated water mol­ecules and sulfonate groups directs the packing.