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A new quinoline derivative, namely, 6-(diethylamino)-4-phenyl-2-(pyridin-2-yl)quinoline, C24H23N3 (QP), and its MnII complex aqua-1κO-di-μ-chlorido-1:2κ4Cl:Cl-dichlorido-1κCl,2κCl-bis[6-(diethylamino)-4-phenyl-2-(pyridin-2-yl)quinoline]-1κ2N1,N2;2κ2N1,N2-dimanganese(II), [Mn2Cl4(C24H23N3)2(H2O)] (MnQP), were synthesized. Their compositions have been determined with ESI-MS, IR, and 1H NMR spectroscopy. The crystal-structure determination of MnQP revealed a dinuclear complex with a central four-membered Mn2Cl2 ring. Both MnII atoms bind to an additional Cl atom and to two N atoms of the QP ligand. One MnII atom expands its coordination sphere with an extra water molecule, resulting in a distorted octahedral shape. The second MnII atom shows a distorted trigonal–bipyramidal shape. The UV–vis absorption and emission spectra of the examined compounds were studied. Furthermore, when investigating the aggregation-induced emission (AIE) properties, it was found that the fluorescent color changes from blue to green and eventually becomes yellow as the fraction of water in the THF/water mixture increases from 0% to 99%. In particular, these color and intensity changes are most pronounced at a water fraction of 60%. The crystal structure contains disordered solvent molecules, which could not be modeled. The SQUEEZE procedure [Spek (2015). Acta Cryst. C71, 9–18] was used to obtain information on the type and quantity of solvent molecules, which resulted in 44 electrons in a void volume of 274 Å3, corresponding to approximately 1.7 molecules of ethanol in the unit cell. These ethanol molecules are not considered in the given chemical formula and other crystal data.

Three organoplatinum(II) complexes bearing natural arylolefin and quinoline derivatives, namely, [4-methoxy-5-(2-methoxy-2-oxoethoxy)-2-(prop-2-en-1-yl)phenyl](quinolin-8-olato)platinum(II), [Pt(C13H15O4)(C9H6NO)], (I), [4-methoxy-5-(2-oxo-2-propoxyethoxy)-2-(prop-2-en-1-yl)phenyl](quinoline-2-carboxylato)platinum(II), [Pt(C15H19O4)(C10H6NO2)], (II), and chlorido[4-methoxy-5-(2-oxo-2-propoxyethoxy)-2-(prop-2-en-1-yl)phenyl](quinoline)platinum(II), [Pt(C15H19O4)Cl(C9H7N)], (III), were synthesized and structurally characterized by IR and 1H NMR spectroscopy, and by single-crystal X-ray diffraction. The results showed that the cycloplatinated arylolefin coordinates with PtII via the carbon atom of the phenyl ring and the C=Colefinic group. The deprotonated 8-hydroxyquinoline (C9H6NO) and quinoline-2-carboxylic acid (C10H6NO2) coordinate with the PtII atom via the N and O atoms in complexes (I) and (II) while the quinoline (C9H7N) coordinates via the N atom in (III). Moreover, the coordinating N atom in complexes (I)–(III) is in the cis position compared to the C=Colefinic group. The crystal packing is characterized by C—H...π, C—H...O [for (II) and (III)], C—H...Cl [for (III) and π–π [for (I)] interactions.

The complex [Pt(C9H6NO)Cl(C2H4)], (I), was synthesized and structurally characterized by ESI mass spectrometry, IR, NMR spectroscopy, DFT calculations and X-ray diffraction. The results showed that the deprotonated 8-hydroxyquinoline (C9H6NO) coordinates with the PtII atom via the N and O atoms while the ethylene coordinates in the η2 manner and in the trans position compared to the coordinating N atom. The crystal packing is characterized by C—H...O, C—H...π, Cl...π and Pt...π interactions. Complex (I) showed high selective activity against Lu-1 and Hep-G2 cell lines with IC50 values of 0.8 and 0.4 µM, respectively, 54 and 33-fold more active than cisplatin. In particular, complex (I) is about 10 times less toxic to normal cells (HEK-293) than cancer cells Lu-1 and Hep-G2. Furthermore, the reaction of complex (I) with guanine at the N7 position was proposed and investigated using the DFT method. The results indicated that replacement of the ethylene ligand with guanine is thermodynamically more favorable than the Cl ligand and that the reaction occurs via two consecutive steps, namely the replacement of ethylene with H2O and the water with the guanine molecule.

The title compound, C27H20N4O3S, crystallizes in the monoclinic system, space group P21/n, with Z = 4. The global shape of the molecule is determined by the orientation of the substituents on the central 4H-1,2,4-triazole ring. The nitrophenyl ring, phenyl ring, and naphthalene ring system are oriented at dihedral angles of 82.95 (17), 77.14 (18) and 89.46 (15)°, respectively, with respect to the triazole ring. The crystal packing features chain formation in the b-axis direction by S...O interactions. A Hirshfeld surface analysis indicates that the highest contributions to surface contacts arise from contacts in which H atoms are involved.

The molecular and crystal structure of (E)-2-[(benzo[d]thiazol-2-ylimino)methyl]-5-(diethylamino)phenol (C18H19N3O2S, Et2N-Bz) and its unexpected reaction product with triphenylborane, 2,2-diphenyl-1,3-dioxa-2-borata-1,2-dihydronaphthalene [systematic name: N,N-diethyl-2,2-diphenyl-2H-1,3λ3,2λ4-benzodioxaborinin-7-amine, C23H24BNO2, (I)] are described. For Et2N-Bz, the hydroxyl group is involved in an intramolecular hydrogen bond with the imino nitrogen atom and the C=N bond displays an E configuration. The crystal packing is characterized by layers of inversion dimers parallel to the (10\overline{1}) plane and chains of molecule in the a-axis direction formed through C—H...O interactions. Complex (I) crystallizes with two molecules (A and B) in the asymmetric unit, which differ in the orientation of the ethyl groups. The 1,3-dioxa-2-borata-1,2,3,4-tetrahydronaphthalene ring displays a slight envelope conformation with the boron atom as the flap. In the crystal packing, chains of alternating A and B molecules formed by C—H...O hydrogen bonds run in the b-axis direction. The UV–vis absorption and emission properties of the compounds are discussed and their aggregation-induced emission properties are further investigated.

Methyl 4-(1,3a,6a-triazapentalen-3-yl)benzoate (TAP1) shows interesting properties as a small molecule fluorophore. In the search for post-functionalization methods, palladium-catalyzed arylation reactions were demonstrated. Direct CH arylation reactions of TAP1 with various aryl halides resulted in 3,6-diaryltriazapentalenes TAP4, although mostly in poor yields. Bromination of TAP1 followed by Suzuki coupling, on the other hand, requires a more delicate procedure, but gave arylated products with the same regiochemistry (TAP4) in moderate to good yields. The structure of 6-phenyltriazapentalene TAP4a was confirmed by crystallographic analysis. In addition, the effect of the C6 arylation on the fluorescent properties of 3-aryl-1,3a,6a-triazapentalenes was studied in dichloromethane at room temperature and in 2-methyltetrahydrofuran at 77 K, while the photophysical properties of two saponified derivatives were measured in acetonitrile.

Overall, drug design is a dynamic and evolving field, with researchers constantly working to improve their understanding of molecular interactions, develop new computational methods, and explore innovative techniques for creating effective and safe medications. The process can involve steps such as the identification of targets, the discovery of lead compounds, lead optimization, preliminary testing, human trials, regulatory approval and finally post-marketing surveillance, all aimed at bringing a new drug from concept to market. In this article, the synthesis of the novel triazolequinoxalin (TZQ) 1-((1-hexyl-1H-1,2,3-triazol-5-yl)methyl)-3-phenylquinoxalin-2(1H)-one (4) is reported. The structure has been identified with a variety of spectroscopic methods (1H, 13C NMR, and LC-MS) and finally, the structure has been determined by X-ray diffraction (XRD) studies. The TZQ molecule has crystallized in the monoclinic space C2/c group with unit cell dimensions a = 41.201(2) Å, b = 10.6339(6) Å, c = 9.4997(4) Å, β = 93.904(4). The crystal structure is stabilized by intermolecular interactions (N–H ⋯ O and N–H … Cg) occurring within the molecule. The presence of these intermolecular interactions is evaluated through analysis of Hirshfeld surfaces (HS) and two-dimensional (2D) chemical fingerprints map. Additionally, energy frameworks were employed to identify the prevailing interaction energy influencing the molecular arrangement. Density Functional Theory (DFT) calculations were computed to establish concurrence between theoretical and experimental results. Furthermore, the HOMO-LUMO energy levels were determined using the B3LYP/6-31+G(d, p) level of theory. Finally, molecular docking was used to predict the anti-cancer activity of the compound (4) against PFKFB3 kinase and presented noticeable hydrophilic and hydrophobic interactions at the active site region.

The Nenitzescu reaction is a condensation reaction between an enamine and a quinone, which can give rise to a wide variety of reaction products depending on the nature of the starting material and the reaction conditions. The most commonly observed products are 5-hydroxyindoles and 5-hydroxybenzofurans. Both classes are of interest since they are known to possess a variety of promising bioactivities. Despite the high chemodivergency for this reaction, it remains an interesting synthetic strategy thanks to the mild reaction conditions, easily accessible starting materials and simple reaction procedures. For these reasons, our research group investigated the Nenitzescu reaction of piperazinone enaminoesters, resulting in the unexpected formation of rearranged 2-imidazolidinone benzofurans. In this work, we aimed to develop reaction conditions that favor the formation of 5-hydroxyindoles via an extensive, multivariate optimization study. This led to valuable insights into the parameters that influence regio- and chemoselectivity. Furthermore, two novel products were obtained, a pyrrolo[2,3-f]indole and a benzofuranone, both of which are rarely reported in the literature.

The title compound, C10H14BrN5O2S, is the bromobenzenesulfonamide derivative of the type 2 diabetes drug metformin. The asymmetric unit contains two molecules with almost identical conformations but a different orientation of the bromophenyl moiety. Both molecules exhibit intramolecular N—H...N and N—H...O hydrogen bonds. The molecular packing features chain formation in the a-axis direction by alternating N—H...N and N—H...O interactions. In addition, ring motifs consisting of four molecules and π–π interactions between the phenyl rings contribute to the three-dimensional architecture. A Hirshfeld surface analysis shows that the largest contributions to surface contacts arise from contacts in which H atoms are involved.

Disubstituted isothiazolo[4,3-b]pyridines are known inhibitors of cyclin G-associated kinase. Since 3-substituted-7-aryl-isothiazolo[4,3-b]pyridines remain elusive, a strategy was established to prepare this chemotype, starting from 2,4-dichloro-3-nitropyridine. Selective C-4 arylation using ligand-free Suzuki-Miyaura coupling and palladium-catalyzed aminocarbonylation functioned as key steps in the synthesis. The 3-N-morpholinyl-7-(3,4-dimethoxyphenyl)-isothiazolo[4,3-b]pyridine was completely devoid of GAK affinity, in contrast to its 3,5- and 3,6-disubstituted congeners. Molecular modeling was applied to rationalize its inactivity as a GAK ligand.

Eight polythiophene derivatives containing pyrazoline side groups were synthesized by a chemical oxidative coupling polymerization using FeCl3. The crystal structures of four monomers were determined which confirm the almost perpendicular orientation of the thiophene and pyrazoline rings, while the other substituents are more coplanar. Analyses of IR, 1H-NMR, Raman and UV-Vis spectra demonstrated that the suggested polymerization was successful to generate the synthesized polythiophenes with the expected structures. The morphology of the synthesized polythiophenes was studied by SEM. The different substituents attached to the 1- and 3-positions of the pyrazoline side chain led to differences in optical properties, electrical conductivity, and thermal stability of the synthesized polythiophenes. By adding a pyrazoline side chain to polythiophenes, some polymers achieve good solubility, electrical conductivity of about 1.3 × 10–6 S/cm, high fluorescence intensity (above 40,000 a.u.) at 505–550 nm and thermal stability up to 590°C in the air.

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. As these artificial sweeteners are also known to induce a cool sensation in the mouth, 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 (ΔHdiss). The choice of these two sweeteners also allows use of the freely available WebCSD and Mercury tools to visualize their three-dimensional structure, crystal packing and powder diffractograms, and to deepen stereochemical concepts such as stereoisomers and meso compounds.

Substituted 4-acetyl-3-hydroxy-3-pyrroline-2-ones have been prepared via three-component reactions and the tautomerism of these 3-pyrroline-2-ones is due to the slight difference of energy, and the significantly large rate constant of transformation between two tautomers. 1,4,5-Trisubstituted pyrrolidine-2,3-dione derivatives were prepared from the above mentioned 2-pyrrolidinone derivatives and aliphatic amines, which exist in enamine form and are stabilized by an intramolecular hydrogen bond. A possible reaction mechanism between 3-pyrroline-2-one and aliphatic amine (CH3NH2) was proposed based on computational results and the main product is formed favorably following the PES via the lowest ΔG# pathway in both the gas-phase and an ethanol solvent model. DFT calculations showed that kinetic selectivity is more significant than thermodynamic selectivity for forming main products.

In this work, a novel compound N-(3-(4-methoxyphenyl)isoxazolin-5-yl)methylsaccharin has been synthesized. The molecular structure of the compound was determined using various spectroscopic techniques and confirmed by a single-crystal X-ray diffraction analysis. In the single crystal, C–H…O hydrogen bonds between neighboring molecules form chains along the a-axis direction. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H…H (35.7%), H…O/O…H (33.7%), and H…C/C…H (13%) interactions. The optimized structure calculated using density functional theory at the B3LYP/6–311 G(d,p) level is compared with the experimentally determined structure in the solid state. The calculated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy gap is 4.9266 eV.

The synthesis and spectroscopic data of (E)-2-{4-[3-(thiophen-3-yl)acryloyl]phenoxy}acetic acid are described. Crystallization from an ethanol–water mixture resulted in the title compound, C30H23KO8S2 or [K(C15H11O4S)(C15H12O4S)]n, containing one molecule of the acid and one molecule of the potassium salt in the asymmetric unit. Both molecules share the H atom between their carboxyl groups and a potassium ion. The C=C bonds display an E configuration. The thiophene and phenyl rings in the two molecules are inclined by 43.3 (2) and 22.7 (2)°. The potassium ion is octahedrally coordinated by six O atoms. This distorted octahedron shares on opposite sides two oxygen atoms with inversion-related octahedra, resulting in chains of octahedra running in the [010] direction, which form ladder-like chains by C—H...π interactions. A Hirshfeld surface analysis indicates that the highest contributions to the surface contacts arise from interactions in which H atoms are involved, with the most important contribution being from H...H (31.6 and 31.9% for the two molecules) interactions.

In the title molecule, C13H13N3O, the isoxazole ring is inclined to the benzimidazole ring at a dihedral angle of 69.28 (14)°. In the crystal, N—H...N hydrogen bonds between neighboring benzimidazole rings form chains along the a-axis direction. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H...H (48.8%), H...C/C...H (20.9%) and H...N/N...H (19.3%) interactions. The optimized structure calculated using density functional theory at the B3LYP/6–311 G(d,p) level is compared with the experimentally determined structure in the solid state. The calculated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy gap is 4.9266 eV.

The title compound N-(4-methoxyphenyl)-2-[4-(3-oxo-3-phenylprop-1-en-1-yl)phenoxy]acetamide, C24H21NO4, was prepared from reaction of N-(4-methoxyphenyl)-2-chloroacetamide and (E)-3-(4-hydroxyphenyl)-1-phenylprop-2-en-1-one, which was obtained from the reaction of 4-hydroxybenzaldehyde and acetophenone. The structure of the title compound was determined by IR, 1H-NMR, 13C-NMR and HR–MS spectroscopic data and further characterized by single-crystal X-ray diffraction. The asymmetric unit contains four molecules, each displaying an E-configuration of the C=C bond. The dihedral angle between the phenyl rings in each molecule varies between 14.9 (2) and 45.8 (2)°. In the crystal, C—H...O hydrogen-bonding interactions link the molecules into chains running along the [001] direction. In addition, C—H...π interactions further stabilize the crystal packing. A Hirshfeld analysis indicates that the most important contributions to the surface contacts are from H...H (43.6%), C...H/H...C (32.1%) and O...H/H...O (18.1%) interactions.

Three new platinum(II) complexes bearing a eugenol and a pyridine derivative, namely (η2-2-allyl-4-methoxy-5-{[(propan-2-yloxy)carbonyl]methoxy}phenyl-κC1)chlorido(pyridine-κN)platinum(II), [Pt(C15H19O4)Cl(C5H5N)], (I), (η2-2-allyl-4-methoxy-5-{[(propan-2-yloxy)carbonyl]methoxy}phenyl-κC1)chlorido(4-methylpyridine-κN)platinum(II), [Pt(C15H19O4)Cl(C6H7N)], (II), and (η2-2-allyl-4-methoxy-5-{[(propan-2-yloxy)carbonyl]methoxy}phenyl-κC1)chlorido(pyridine-4-carboxylic acid-κN)platinum(II), [Pt(C15H19O4)Cl(C6H5NO2)], (III), have been synthesized and further characterized by single-crystal X-ray diffraction. The PtII atoms exhibit the usual distorted square-planar coordination and are surrounded by one Cl atom, one N atom, and a C atom and C=C double bond of the eugenol ligand. The donor N atom of the pyridine ligand occupies a cis position with respect to the double bond. Complexes (I) and (II) crystallize isomorphously in space group P\overline{1} and display a similar crystal packing characterized by C—H...O hydrogen bonding, C—H...π and π–π interactions. However, the presence of the additional methyl group in the 4-methylpyridine ligand in (II) disturbs the π–π interactions. The crystal packing of (III) is characterized by O—H...O hydrogen bonding, resulting in the formation of chains of molecules connected in a head-to-tail fashion and running in the [101] direction. The IC50 values for the HepG2 and KB cell lines are 150.9, 122.3 µM for (I) and 138.9, 93.2 µM for (II), respectively.

The title compound, C18H16N2O3S, was synthesized by reaction of 2-mercapto-3-phenylquinazolin-4(3H)-one with ethyl chloroacetate. The quinazoline ring forms a dihedral angle of 86.83 (5)° with the phenyl ring. The terminal methyl group is disordered by a rotation of about 60° in a 0.531 (13): 0.469 (13) ratio. In the crystal, C—H...O hydrogen-bonding interactions result in the formation of columns running in the [010] direction. Two parallel columns further interact by C—H...O hydrogen bonds. The most important contributions to the surface contacts are from H...H (48.4%), C...H/H...C (21.5%) and O...H/H...O (18.7%) interactions, as concluded from a Hirshfeld analysis.

In the title compound, C17H21NO4S, the 1,4-dihydropyridine ring has an envelope conformation with the Csp3 atom at the flap. The thiophene ring is nearly perpendicular to the best plane through the 1,4-dihydropyridine ring, the dihedral angle being 82.19 (13)°. In the crystal, chains running along the b-axis direction are formed through N—H...O interactions between the 1,4-dihydropyridine N atom and one of the O atoms of the ester groups. Neighbouring chains are linked by C—H...O and C—H...π interactions. A Hirshfeld surface analysis shows that the most prominent contributuion to the surface contacts are H...H contacts (55.1%).

In the title pyrazoline derivative, C16H16N2O3·H2O, the pyrazoline ring has an envelope conformation with the substituted sp2 C atom on the flap. The pyrazoline ring makes angles of 86.73 (12) and 13.44 (12)° with the trisubstituted and disubstituted benzene rings, respectively. In the crystal structure, the molecules are connected into chains running in the b-axis direction by O—H...N hydrogen bonding. Parallel chains interact through N—H...O hydrogen bonds and π–π stacking of the trisubstituted phenyl rings. The major contribution to the surface contacts are H...H contacts (44.3%) as concluded from a Hirshfeld surface analysis.

The structure of the title compound (systematic name: N-{[(2-hydroxyphenyl)methylidene]amino}morpholine-4-carbothioamide), C12H15N3O2S, was previously determined (Koo et al., 1977) using multiple-film equi-inclination Weissenberg data, but has been redetermined with higher precision to explore its conformation and the hydrogen-bonding patterns and supramolecular interactions. The molecular structure shows intramolecular O—H...N and C—H...S interactions. The configuration of the C=N bond is E. The molecule is slightly twisted about the central N—N bond. The best planes through the phenyl ring and the morpholino ring make an angle of 43.44 (17)°. In the crystal, the molecules are connected into chains by N—H...O and C—H...O hydrogen bonds, which combine to generate sheets lying parallel to (002). The most prominent contribution to the surface contacts are H...H contacts (51.6%), as concluded from a Hirshfeld surface analysis.

The synthesis, spectroscopic data, crystal and molecular structures of two N′-(1-phenylbenzylidene)-2-(thiophen-3-yl)acetohydrazides, namely N′-[1-(4-hydroxyphenyl)benzylidene]-2-(thiophen-3-yl)acetohydrazide, C13H10N2O2S, (3a), and N′-[1-(4-methoxyphenyl)benzylidene]-2-(thiophen-3-yl)acetohydrazide, C14H14N2O2S, (3b), are described. Both compounds differ in the substituent at the para position of the phenyl ring: –OH for (3a) and –OCH3 for (3b). In (3a), the thiophene ring is disordered over two orientations with occupancies of 0.762 (3) and 0.238 (3). The configuration about the C=N bond is E. The thiophene and phenyl rings are inclined by 84.0 (3) and 87.0 (9)° for the major- and minor-occupancy disorder components in (3a), and by 85.89 (12)° in (3b). Although these dihedral angles are similar, the conformation of the linker between the two rings is different [the C—C—C—N torsion angle is −ac for (3a) and −sc for (3b), while the C6—C7—N9—N10 torsion angle is +ap for (3a) and −sp for (3b)]. A common feature in the crystal packing of (3a) and (3b) is the presence of N—H...O hydrogen bonds, resulting in the formation of chains of molecules running along the b-axis direction in the case of (3a), or inversion dimers for (3b). The most prominent contributions to the surface contacts are those in which H atoms are involved, as confirmed by an analysis of the Hirshfeld surface.

The synthesis, spectroscopic data and crystal and molecular structures of four 3-(3-phenylprop-1-ene-3-one-1-yl)thiophene derivatives, namely 1-(4-hydroxyphenyl)-3-(thiophen-3-yl)prop-1-en-3-one, C13H10O2S, (1), 1-(4-methoxyphenyl)-3-(thiophen-3-yl)prop-1-en-3-one, C14H12O2S, (2), 1-(4-ethoxyphenyl)-3-(thiophen-3-yl)prop-1-en-3-one, C15H14O2S, (3), and 1-(4-bromophenyl)-3-(thiophen-3-yl)prop-1-en-3-one, C13H9BrOS, (4), are described. The four chalcones have been synthesized by reaction of thiophene-3-carbaldehyde with an acetophenone derivative in an absolute ethanol solution containing potassium hydroxide, and differ in the substituent at the para position of the phenyl ring: –OH for 1, –OCH3 for 2, –OCH2CH3 for 3 and –Br for 4. The thiophene ring in 4 was found to be disordered over two orientations with occupancies 0.702 (4) and 0.298 (4). The configuration about the C=C bond is E. The thiophene and phenyl rings are inclined by 4.73 (12) for 1, 12.36 (11) for 2, 17.44 (11) for 3 and 46.1 (6) and 48.6 (6)° for 4, indicating that the –OH derivative is almost planar and the –Br derivative deviates the most from planarity. However, the substituent has no real influence on the bond distances in the α,β-unsaturated carbonyl moiety. The molecular packing of 1 features chain formation in the a-axis direction by O—H...O contacts. In the case of 2 and 3, the packing is characterized by dimer formation through C—H...O interactions. In addition, C—H...π(thiophene) interactions in 2 and C—H...S(thiophene) interactions in 3 contribute to the three-dimensional architecture. The presence of C—H...π(thiophene) contacts in the crystal of 4 results in chain formation in the c-axis direction. The Hirshfeld surface analysis shows that for all four derivatives, the highest contribution to surface contacts arises from contacts in which H atoms are involved.

β-Propeller proteins form one of the largest families of protein structures, with a pseudo-symmetrical fold made up of subdomains called blades. They are not only abundant but are also involved in a wide variety of cellular processes, often by acting as a platform for the assembly of protein complexes. WD40 proteins are a subfamily of propeller proteins with no intrinsic enzymatic activity, but their stable, modular architecture and versatile surface have allowed evolution to adapt them to many vital roles. By computationally reverse-engineering the duplication, fusion and diversification events in the evolutionary history of a WD40 protein, a perfectly symmetrical homologue called Tako8 was made. If two or four blades of Tako8 are expressed as single polypeptides, they do not self-assemble to complete the eight-bladed architecture, which may be owing to the closely spaced negative charges inside the ring. A different computational approach was employed to redesign Tako8 to create Ika8, a fourfold-symmetrical protein in which neighbouring blades carry compensating charges. Ika2 and Ika4, carrying two or four blades per subunit, respectively, were found to assemble spontaneously into a complete eight-bladed ring in solution. These artificial eight-bladed rings may find applications in bionanotechnology and as models to study the folding and evolution of WD40 proteins.

In recent decades, considerable research attention has been devoted to new synthetic procedures for thiacyclophanes. Thiacyclophanes are widely used as host molecules for the molecular recognition of organic compounds as well as metals. Herein, we report the selective and high-yielding synthesis of novel alternate-linked-meta-para-thiacyclophanes. These novel thiacyclophanes are selectively synthesized in high-yielding procedures. Furthermore, post-functionalization of the phenolic moieties was successfully performed. The 3D structure of the alternate-linked-meta-para-[22.12]thiacyclophane was further elucidated via X-ray crystallographic analysis.

In the title compound, C15H14IN3O2·CH3OH, two aromatic rings are linked by an N-substituted hydrazide function. The dihedral angle between the aromatic rings is 10.53 (8)°. The stereochemistry about the imine function is E. The methanol molecule forms an O—H...O hydrogen bond to the hydrazide O atom. In the crystal, chains of molecules running along the c-axis direction are formed by O—H...O hydrogen bonds. Adjacent chains are linked through N—H...O hydrogen bonds and π–π stacking interactions. The intermolecular interactions in the crystal packing were investigated using Hirshfeld surface analysis, which indicated that the most significant contacts are H...H (38.2%), followed by C...H/H...C (20.6%), O...H/H...O (11.1%) and I...H/H...I (9.7%).

In the title compound, C13H11N3S2, the phenyl ring is twisted from the 1,2,4-triazole plane by 63.35 (9)° and by 47.35 (9)° from the thiophene plane. In the crystal, chains of molecules running along the c-axis direction are formed by N—H...S interactions [graph-set motif C(4)]. The 1,2,4-triazole and phenyl rings are involved in π–π stacking interactions [centroid–centroid distance = 3.4553 (10) Å]. The thiophene ring is involved in C—H...S and C—H...π interactions. The intermolecular interactions in the crystal packing were further analysed using Hirshfield surface analysis, which indicates that the most significant contacts are H...H (35.8%), followed by S...H/H...S (26.7%) and C...H/H...C (18.2%).

A practical three-step protocol for the assembly of triazolobenzodiazepine-fused diketopiperazines and hydantoins has been developed. The synthesis of these tetracyclic ring systems was initiated by an Ugi reaction, which brought together all necessary functionalities for further transformations. The Ugi adducts were then subjected to a base-induced ring closing and an intramolecular azide–alkyne cycloaddition reaction in succession to obtain highly fused benzodiazepine frameworks.

Steviol glycosides were subjected to bacteria present in a soil sample collected from a Stevia plantation in Paraguay. During the incubation experiments, next to the aglycon steviol, steviol degradation products were also formed. X-ray analysis and NMR methods in combination with chemical synthesis and GIAO NMR calculations were used to fully characterize the structure of these compounds as a tricyclic ketone and the corresponding reduced form. They were nicknamed monicanone and monicanol. The latter has the (S)-configuration at the alcohol site.

The title compound, C11H7NS2, was prepared in high yield (87%) using a solvent-free microwave-assisted synthesis. The structure shows whole-molecule disorder with occupancies for two orientations (A and B) of 0.4884 (10) and 0.5116 (10), respectively. The thiophene and benzothiazole rings are almost planar and make dihedral angles of 10.02 (18) and 12.54 (19)° for orientations A and B, respectively. Slipped π–π stacking between the aromatic rings, together with C—H...π, C—H...S and C—H...N interactions, result in a herringbone motif in the crystal packing.

In the title compound, C7H8N4S2, the thiophene ring shows rotational disorder over two orientations in a 0.6957 (15):0.3043 (15) ratio. The plane of the 1,2,4-triazole ring makes a dihedral angle of 75.02 (17)° with the major-disorder component of the thiophene ring. In the crystal, two types of inversion dimers, described by the graph-set motifs R22(8) and R22(10), are formed by N—H...S interactions. Chains of molecules running in the [101] direction are linked by weaker N—H...N interactions. The thiophene ring is involved in π–π and C—H...π interactions.

The title compound, C9H8N2O2S3, crystallizes with two molecules (A and B) in the asymmetric unit. Both have similar conformations (overlay r.m.s. deviation = 0.209 Å) and are linked by an N—H...O hydrogen bond. In both molecules, the thiophene rings show orientational disorder, with occupancy factors of 0.6727 (17) and 0.3273 (17) for molecule A, and 0.7916 (19) and 0.2084 (19) for molecule B. The five-membered rings make an angle of 79.7 (2)° in molecule A and an angle of 66.8 (2)° in molecule B. In the crystal, chains of molecules running along the a-axis direction are linked by N—H...O hydrogen bonds. The interaction of adjacent chains through N—H...O hydrogen bonds leads to two types of ring structures containing four molecules and described by the graph-set motifs R44(18) and R42(14).

The title compound, C17H12BrN3O2, was unexpectedly isolated during an attempt to synthesize pyridodiazepinediones and identified as an oxazolonaphthyridinone derivative. The almost planar oxazolonaphthyridinone ring (r.m.s. deviation = 0.016 Å) makes a dihedral angle of 61.6 (2)° with the phenyl ring. In the crystal, columns of molecules stacked along the a axis are formed by π–π interactions between the six-membered rings of the oxazolonaphthyridone moieties [centroid-to-centroid distances = 3.494 (2)–3.906 (3) Å], which further interact through C—H...π contacts with the phenyl rings.

In the title complexes, trans-(2-aminopyridine-κN)dichlorido{4-ethoxycarbonylmethoxy-3-methoxy-1-[(2,3-η)-prop-2-en-1-yl]benzene}platinum(II), [PtCl2(C5H6N2)(C14H18O4)], (I), and (2-aminopyridine-κN)chlorido{5-ethoxycarbonylmethoxy-4-methoxy-1-[(2,3-η)-prop-2-en-1-yl]phenyl-κC1}platinum(II), [Pt(C14H17O4)Cl(C5H6N2)], (II), the central PtII metal atom displays a distorted square-planar coordination, with the PtII atom coordinated by the pyridine N atom, the C=C double bond of the eugenol ligand and two Cl atoms for (I) or one Cl atom and a C atom of the phenyl ring for (II). The allyl fragment in (I) is disordered, with population parameters 0.614 (14) and 0.386 (14) for the two positions of the central C atom. The least-squares planes through the two aromatic ring systems make a dihedral angle of 51.10 (13)° for (I) and 78.5 (2)° for (II). Intramolecular N—H...O and N—H...π interactions occur in (I). In (I), inversion dimers formed by C—H...Cl interactions are further linked into chains parallel to the b axis by C—H...O hydrogen bonds. Both aromatic rings are involved in π–π interactions, with centroid-to-centroid distances of 3.508 (3) and 3.791 (3) Å. In (II), inversion dimers form chains parallel to the b axis by C—H...O interactions.

Facile synthetic routes for three 4-substituted 2,2′-bipyridine derivatives, 4-[2-(4-methylphenyl)ethynyl]-2,2′-bipyridine, C19H14N2, (I), 4-[2-(pyridin-3-yl)ethynyl]-2,2′-bipyridine, C17H11N3, (II), and 4-(indol-4-yl)-2,2′-bipyridine, C18H13N3, (III), via Sonogashira and Suzuki–Miyaura cross-coupling reactions, respectively, are described. As indicated by X-ray analysis, the 2,2′-bipyridine core, the ethylene linkage and the substituents of (I) and (II) are almost planar [dihedral angles between the two ring systems: 8.98 (5) and 9.90 (6)° for the two molecules of (I) in the asymmetric unit and 2.66 (14)° for (II)], allowing π-conjugation. On the contrary, in (III), the indole substituent ring is rotated significantly out of the bipyridine plane [dihedral angle = 55.82 (3)°], due to steric hindrance. The crystal packings of (I) and (II) are dominated by π–π interactions, resulting in layers of molecules parallel to (30-2) in (I) and columns of molecules along the a axis in (II). The packing of (III) exhibits zigzag chains of molecules along the c axis interacting through N—H...N hydrogen bonds and π–π interactions. The contributions of unknown disordered solvent molecules to the diffraction intensities in (II) were removed with the SQUEEZE [Spek (2015). Acta Cryst. C71, 9–18] algorithm of PLATON. The given chemical formula and other crystal data do not take into account these solvent molecules.

The asymmetric unit of the title compound, [Ni(H2O)6](C12H12BrN2O5S)2·H2O, contains a half hexaaquanickel(II) complex cation with the NiII ion lying on an inversion center, one 5-bromo-7-[(2-hydroxyethyl)amino]-1-methyl-6-oxidoquinolin-1-ium-3-sulfonate (QAO) anion and a half lattice water molecule on a twofold rotation axis. In the crystal, QAO anions are stacked in a column along the c axis by π–π stacking interactions [centroid–centroid distances 3.5922 (10)–3.7223 (11) Å]. The columns are interlinked by hexaaquanickel(II) cations through O—H...O and N—H...O hydrogen bonds.

In the title complexes, trans-dichlorido(4-chloroaniline-κN){3-methoxy-4-methoxycarbonylmethoxy-1-[(2,3-η)-prop-2-en-1-yl]benzene}platinum(II) 0.1-hydrate, [PtCl2(C6H6ClN)(C13H16O4)]·0.1H2O, (I), and trans-dichlorido(4-chloroaniline-κN){4-ethoxycarbonylmethoxy-3-methoxy-1-[(2,3-η)-prop-2-en-1-yl]benzene}platinum(II), [PtCl2(C6H6ClN)(C14H18O4)], (II), the PtII metal atom displays a slightly distorted square-planar coordination geometry defined by the aniline N atom, two chloride anions (trans-positioned) and one ethylenic double bond. The least-squares planes through the two aromatic ring systems make an angle of 47.3 (3)° for (I) and 38.6 (2)° for (II). Both structures show disorder for the PtCl2 fragment, in the case of (I) even further extended towards the CH2—CH=CH2 ligand. An intramolecular C—H...Cl hydrogen bond occurs in (I). In the crystal packing of (I), which is dominated by N—H...O and C—H...Cl interactions, a partially occupied water molecule is observed on a twofold rotation axis with a refined site occupancy of 0.10 (1). A C—H...π interaction is also present. In (II), inversion dimers form chains along the b-axis direction by N—H...O hydrogen bonds.

The asymmetric unit of the title compound, [Ni(H2O)6](C11H8NO8S)2·2H2O, features a half-hexaaquanickel(II) complex cation with the NiII ion on an inversion center, one deprotonated 5,6-dihydroxy-3-sulfoquinolin-7-yloxyacetic acid (QOH) molecule appearing in its zwitterionic form and one lattice water molecule. The sulfonate group is disordered over two positions with occupancy factors of 0.655 (5) and 0.345 (5). The hexaaquanickel(II) cation interacts through hydrogen bonding with eight QOH molecules and two water molecules. The six-membered rings of quinoline show π–π stacking [centroid-to-centroid distances of 3.679 (2) Å and 3.714 (2) Å].

The title compound, Ca2+xNd8–x(SiO4)6O2–0.5x (x = 0.49), was synthesized at 1873 K and rapidly quenched to room temperature. Its structure has been determined using single-crystal X-ray diffraction and compared with results reported using neutron and X-ray powder diffraction from samples prepared by slow cooling. The single-crystal structure from room temperature data was found to belong to the space group P63/m and has the composition Ca2.49Nd7.51(SiO4)6O1.75 [dicalcium octaneodymium hexakis(orthosilicate) dioxide], being isotypic with natural apatite and the previously reported Ca2Nd8(SiO4)6O2 and Ca2.2Nd7.8(SiO4)6O1.9. The solubility limit of calcium in the equilibrium state at 1873 K was found to occur at a composition of Ca2+xNd8–x(SiO4)6O2–0.5x, where x = 0.49.

In the title complex, [PtCl2(C5H11N)(C6H6N2O2)], the PtII metal atom displays a slightly distorted trans-PtN2Cl2 square-planar coordination geometry. The dihedral angle between the mean plane of the benzene and piperidine rings is 89.03 (3)°. In the crystal structure, inversion dimers are formed via N—H...Cl hydrogen-bond interactions, resulting in chains parallel to the [001] direction. The benzene rings within the chains show π–π stacking interactions [centroid-to-centroid distances of 3.801 (3) Å] and neighbouring chains interact via N—H...O hydrogen bonds.

In the title compound, C20H17NO5, the dihedral angle between the mean plane of the dihydroquinoline ring system (r.m.s. deviation = 0.003 Å) and the benzene ring is 1.83 (11)°. The almost planar conformation is a consequence of an intramolecular O—H...O hydrogen bond and the E configuration about the central C=C bond. In the crystal structure, O—H...O hydrogen bonds generate chains of molecules along the [10-1] direction. These chains are linked via π–π interactions [inter-centroid distances are in the range 3.6410 (16)–3.8663 (17) Å].

In the title compound, [Pt(C11H13O2)Cl(C5H11N)]·C2H5OH, the PtII cation is pentacoordinated in a distorted square-planar geometry. In the crystal, inversion dimers showing C—H...Cl and C—H...π interactions are further stacked in columns along the a axis via C—H...π interactions. The ethanol solvate molecule interacts with neighbouring methoxy groups of methyleugenol through O—H...O hydrogen bonds.

In the title organoplatinum(II) complex, [PtCl2(C5H5N)(C11H14O2)], the methyleugenol ligand only coordinates to the PtII atom through the ethylenic double bond. The coordination is completed by the N atom of the pyridine ligand and two Cl atoms positioned trans with respect to each other. The pyridine and benzene rings are inclined to one another by 68.6 (2)°. In the crystal, molecules are linked via a number of C—H...Cl and C—H...O hydrogen bonds, forming sheets parallel to the bc plane.

The crystal structure of the organoplatinum(II) title complex, [Pt(C9H6NO)(C11H13O2)] or [Pt(methyleugenol)(8-hydroxyquinolinato)], has been determined in order to verify the coordination environment of the PtII cation, which was found to be square-planar with the N and O atoms of the quinolinate ligand cis and trans, respectively, with respect to the ethylenic double bond. The least-squares planes through the two aromatic ring systems make an angle of 39.87 (10)°. In the crystal, chains are formed parallel to [100] sustained by C—H...O hydrogen bonds. Parallel chains further interact via C—H...O and C—H...π contacts. The complex shows interesting activity on four human cancer cell lines with IC50 values between 1.92 and 4.86 µM.

The title molecule, C17H15ClN2O2, is L-shaped with the 4-chlorobenzylidene ring almost coplanar with the planar pyrazolidine ring (r.m.s. deviation = 0.020 Å), making a dihedral angle of 4.83 (17)°. The 4-methoxyphenyl ring is almost normal to the mean plane of the pyrazolidine ring and the 4-chlorobenzylidene ring, with dihedral angles of 87.36 (17) and 89.23 (16)°, respectively. The pyrazolidine ring occurs in the betaine form with a Z configuration for the exocyclic C=N bond. In the crystal, C—H...O and C—H...π interactions generate ribbons of molecules along [1-10].

The title compound, [Pt(C10H6NO2)Cl(C5H11N)], crystallizes with one molecule in the asymmetric unit. The PtII cation has a slightly distorted square-planar coordination environment defined by a chloride anion, the quinoline N atom and a carboxylate O atom of the bidentate quinaldate ligand and a piperidine N atom. An intramolecular C—H...Cl hydrogen bond occurs. In the crystal, molecules are stacked into columns along the c axis by the formation of N—H...Cl and C—H...O hydrogen bonds.