Use of intensity quotients and differences in absolute structure refinement

Pseudallenes A and B, new sulfur-containing ovalicin sesquiterpenoid derivatives with antimicrobial activity from the deep-sea cold seep sediment-derived fungus Pseudallescheria boydii CS-793

Pseudallenes A and B (1 and 2), the new and rare examples of sulfur-containing ovalicin derivatives, along with three known analogues 3-5, were isolated and identified from the culture extract of Pseudallescheria boydii CS-793, a fungus obtained from the deep-sea cold seep sediments. Their structures were established by detailed interpretation of NMR spectroscopic and mass spectrometric data. X-ray crystallographic analysis confirmed and established the structures and absolute configurations of compounds 1-3, thus providing the first characterized crystal structure of an ovalicin-type sesquiterpenoid. In the antimicrobial assays, compounds 1-3 showed broad-spectrum inhibitory activities against several plant pathogens with MIC values ranging from 2 to 16 μg/mL.

(+)-Cedrol hemihydrate: a natural product derived from drying eastern red cedar (Juniperus virginiana) wood

Cedrol-like compounds are of pharmacological interest due to their diverse range of medicinal effects and are used globally in traditional medicines and cosmetics. Many cedrol tautomers are known from molecular studies but few have been studied in crystalline form by X-ray diffraction. Acicular white crystals collected from the wood of eastern red cedar (Juniperus virginiana) are determined to be (+)-cedrol hemihydrate, namely, (1S,2R,5S,7R,8R)-2,6,6,8-tetramethyltricyclo[5.3.1.01,5]undecan-8-ol hemihydrate, C15H26O·0.5H2O, a novel packing of two unique cedrol molecules (Z' = 2) with a single water molecule [space group P212121; a = 6.1956 (1), b = 14.5363 (1), and c = 30.9294 (4) Å]. The hydrogen bonding forms a one-dimensional spiral chain running along the a axis, following the chirality of the cedrol molecule, through hydrogen-bonding interactions with a right-handed helical configuration in graph-set notation Δ-C33(6) > a > c > b. The crystal packing and symmetry are different from crystalline isocedrol due to the different hydrogen-bonding geometry.

High-throughput nanoscale crystallization of dihydropyridine active pharmaceutical ingredients

Single-crystal X-ray diffraction analysis of small molecule active pharmaceutical ingredients is a key technique in the confirmation of molecular connectivity, including absolute stereochemistry, as well as the solid-state form. However, accessing single crystals suitable for X-ray diffraction analysis of an active pharmaceutical ingredient can be experimentally laborious, especially considering the potential for multiple solid-state forms (solvates, hydrates and polymorphs). In recent years, methods for the exploration of experimental crystallization space of small molecules have undergone a `step-change', resulting in new high-throughput techniques becoming available. Here, the application of high-throughput encapsulated nanodroplet crystallization to a series of six dihydropyridines, calcium channel blockers used in the treatment of hypertension related diseases, is described. This approach allowed 288 individual crystallization experiments to be performed in parallel on each molecule, resulting in rapid access to crystals and subsequent crystal structures for all six dihydropyridines, as well as revealing a new solvate polymorph of nifedipine (1,4-dioxane solvate) and the first known solvate of nimodipine (DMSO solvate). This work further demonstrates the power of modern high-throughput crystallization methods in the exploration of the solid-state landscape of active pharmaceutical ingredients to facilitate crystal form discovery and structural analysis by single-crystal X-ray diffraction.

CP, Mendoza Á, Hernández Téllez G. (S)-(+)-1-(4-Bromo-phen-yl)-N-[(4-methoxyphen-yl)methyl-idene]ethyl-amine and bis-{(S)-(+)-1-(4-bromo-phen-yl)-N-[(4-methoxyphen-yl)methyl-idene]ethyl-amine-κN}di-chlorido-palladium(II)

The (S)-(+)-1-(4-bromo-phen-yl)-N-[(4-methoxyphen-yl)methyl-idene]ethyl-amine ligand, C16H16BrNO, (I), was synthesized through the reaction of 4-meth-oxy-anisaldehyde with (S)-(-)-1-(4-bromo-phen-yl)ethyl-amine. It crystallizes in the ortho-rhom-bic space group P212121 belonging to the Sohncke group, featuring a single mol-ecule in the asymmetric unit. The refinement converged successfully, achieving an R factor of 0.0508. The PdII com-plex bis-{(S)-(+)-1-(4-bromo-phen-yl)-N-[(4-methoxyphen-yl)methyl-idene]ethyl-amine-κN}di-chlorido-pal-ladium(II), [PdCl2(C16H16BrNO)2], (II), crystallizes in the monoclinic space group P21 belonging to the Sohncke group, with two mol-ecules in the asymmetric unit. The central atom is tetra-coordinated by two N atoms and two Cl atoms, resulting in a square-planar configuration. The imine moieties exhibit a trans configuration around the PdII centre, with average Cl-Pd-N angles of approximately 89.95 and 90°. The average distances within the palladium com-plex for the two mol-ecules are ∼2.031 Å for Pd-N and ∼2.309 Å for Pd-Cl.

1-Ethyl-3,3-di-methyl-spiro-[indoline-2,8'-phenaleno[1,9-fg]chromene]

The title pyrene-fused spiro-pyran derivative, C30H25NO, crystallizes with two mol-ecules in the asymmetric unit with dihedral angles between their fused-ring sub units of 76.20 (8) and 89.38 (9)°. In the crystal, weak C-H⋯π inter-actions link the mol-ecules into a three-dimensional network.

Synthesis and crystal structure of [1,3-bis-(2,6-diiso-propyl-phen-yl)imidazol-2-yl-idene](iso-cyanato-κN)gold(I)

The title complex, [Au(NCO)(C27H36N2)], was synthesized by ligand metathesis from [1,3-bis-(2,6-diiso-propyl-phen-yl)imidazol-2-yl-idene]gold(I) chloride and sodium cyanate in anhydrous tetra-hydro-furan and crystallized from toluene at 233 K in the ortho-rhom-bic space group P212121, as a neutral complex with the central Au atom di-coordinated by an N-heterocyclic carbene [Au-C = 1.963 (2) Å] and an iso-cyanate [Au-N 1.999 (2) Å] ligands, with a linear CAuNCO moiety. The crystal packing is consolidated by C-H⋯O hydrogen bonds.

Crystal structures of the alkali aluminoboracites A4B4Al3O12Cl (A = Li, Na)

Single crystals of alkali aluminoboracites, A 4B4Al3O12Cl (A = Li, Na), were grown using the self-flux method, and their isotypic cubic crystal structures were determined by single-crystal X-ray diffraction. Na4B4Al3O12Cl is the first reported sodium boracite, and its lattice parameter [13.5904 (1) Å] is the largest among the boracites consisting of a cation-oxygen framework reported so far. For both crystals, structure models refined in the cubic space group F 3c, which assume that all cubic octant subcells in the unit cell are equivalent, converged with R1 factors of ∼0.03. However, the presence of weak hhl reflections with odd h and l values indicates that refinements in the space group F23, which presume a checkerboard-like ordering of two types of subcells with slightly different atomic positions, are more appropriate.

Synthesis and crystal structure of N1,N2-di-methyl-ethane-dihydrazide

The title compound, N 1,N 2-di-methyl-ethane-dihydrazide, C4H10N4O2, was obtained by the methyl-ation of oxalyl dihydrazide protected with phthalimide. The mol-ecule is essentially non-planar with a dihedral angle between the two planar hydrazide fragments of 86.5 (2)°. This geometry contributes to the formation of a multi-contact three-dimensional supra-molecular network via C-H⋯O, N-H⋯O and N-H⋯N hydrogen bonds.

Cadmium phosphates Cd2(PO4)OH and Cd5(PO4)2(OH)4 crystallizing in mineral structures

Single crystals of two basic cadmium phosphates, dicadmium orthophosphate hydroxide, Cd2(PO4)OH, and penta-cadmium bis-(orthophosphate) tetra-kis-(hydroxide), Cd5(PO4)2(OH)4, were obtained under hydro-thermal conditions. Cd2(PO4)OH adopts the triplite [(Mn,Fe)2(PO4)F] structure type. Its asymmetric unit comprises two Cd, one P and five O sites, all situated at the general Wyckoff position 8 f of space group I2/a; two of the O atoms are positionally disordered over two sites, and the H atom could not be localized. Disregarding the disorder, distorted [CdO6] polyhedra form a tri-periodic network by edge-sharing with neighbouring [CdO6] units and by vertex-sharing with [PO4] units. The site associated with the OH group is coordinated by four Cd atoms in a distorted tetra-hedral manner forming 1 ∞[(OH)Cd4/2] chains parallel to [001]. The oxygen environment around the OH site suggests multiple acceptor atoms for possible O-H⋯O hydrogen-bonding inter-actions and is the putative reason for the disorder. Cd5(PO4)2(OH)4 adopts the arsenoclasite [Mn5(AsO4)2(OH)4] structure type. Its asymmetric unit comprises five Cd, two P, and twelve O sites all located at the general Wyckoff position 4 a of space group P212121; the H atoms could not be localized. The crystal structure of Cd5(PO4)2(OH)4 can be subdivided into two main sub-units. One consists of three edge-sharing [CdO6] octa-hedra, and the other of two edge- and vertex-sharing [CdO6] octa-hedra. Each sub-unit forms corrugated ribbons extending parallel to [100]. The two types of ribbons are linked into the tri-periodic arrangement through vertex-sharing and through common [PO4] tetra-hedra. Qu-anti-tative structure comparisons are made with isotypic M 5(XO4)2(OH)4 crystal structures (M = Cd, Mn, Co; X = P, As, V).

Synthesis and crystal structures of boryl ortho-silylaryl tri-fluoro-methane-sulfonates

We report the synthesis and structural characterization of three crystalline borylated ortho-silylaryl tri-fluoro-methane-sulfonates: 5-(4,4,5,5-tetra-methyl-1,3,2-dioxaborolan-2-yl)-2-(tri-methyl-sil-yl)phenyl tri-fluoro-methane-sulfonate, C16H24BF3O5SSi (1a), 4-(4,4,5,5-tetra-methyl-1,3,2-dioxaborolan-2-yl)-2-(tri-methyl-sil-yl)phenyl tri-fluoro-methane-sulfonate, C16H24BF3O5SSi (1b), and 2-methyl-4-(4,4,5,5-tetra-methyl-1,3,2-dioxaborolan-2-yl)-6-(tri-methyl-silyl)phen-yl tri-fluoro-methane-sulfonate, C17H26BF3O5SSi (2), which are versatile aryne precursors. For all three compounds, the heteroatom substituents are almost coplanar with the central aromatic moiety. C-heteroatom bonding metrics are unexceptional and fall withing the typical range of C-B, C-Si, and C-O single bonds. Despite numerous electronegative sites, only weak inter-molecular inter-actions are observed in the solid state.

Synthesis, crystal structure and thermal properties of di-bromido-bis-(2-methyl-pyridine N-oxide-κO)cobalt(II)

Reaction of CoBr2 with 2-methyl-pyridine N-oxide in n-butanol leads to the formation of the title compound, [CoBr2(C6H7NO)2] or [CoBr2(2-methyl-pyridine N-oxide)2]. Its asymmetric unit consists of one CoII cation as well as two bromide anions and two 2-methyl-pyridine N-oxide coligands in general positions. The CoII cations are tetra-hedrally coordinated by two bromide anions and two 2-methyl-pyridine N-oxides, forming discrete complexes. In the crystal structure, these complexes are linked predominantly by weak C-H⋯Br hydrogen bonding into chains that propagate along the crystallographic a-axis. Powder X-ray diffraction (PXRD) measurements indicate that a pure phase was obtained. Thermoanalytical investigations prove that the title compound melts before decomposition; before melting, a further endothermic signal of unknown origin was observed that does not correspond to a phase transition.

α-D-2'-Deoxyadenosine, an irradiation product of canonical DNA and a component of anomeric nucleic acids: crystal structure, packing and Hirshfeld surface analysis

α-D-2'-Deoxyribonucleosides are products of the γ-irradiation of DNA under oxygen-free conditions and are constituents of anomeric DNA. They are not found as natural building blocks of canonical DNA. Reports on their conformational properties are limited. Herein, the single-crystal X-ray structure of α-D-2'-deoxyadenosine (α-dA), C10H13N5O3, and its conformational parameters were determined. In the crystalline state, α-dA forms two conformers in the asymmetric unit which are connected by hydrogen bonds. The sugar moiety of each conformer is arranged in a `clamp'-like fashion with respect to the other conformer, forming hydrogen bonds to its nucleobase and sugar residue. For both conformers, a syn conformation of the nucleobase with respect to the sugar moiety was found. This is contrary to the anti conformation usually preferred by α-nucleosides. The sugar conformation of both conformers is C2'-endo, and the 5'-hydroxyl groups are in a +sc orientation, probably due to the hydrogen bonds formed by the conformers. The formation of the supramolecular assembly of α-dA is controlled by hydrogen bonding and stacking interactions, which was verified by a Hirshfeld and curvedness surface analysis. Chains of hydrogen-bonded nucleobases extend parallel to the b direction and are linked to equivalent chains by hydrogen bonds involving the sugar moieties to form a sheet. A comparison of the solid-state structures of the anomeric 2'-deoxyadenosines revealed significant differences of their conformational parameters.

Crystal structure, Hirshfeld surface analysis and energy frameworks of 1-[(E)-2-(2-fluoro-phen-yl)diazan-1-yl-idene]naphthalen-2(1H)-one

The title compound, C16H11N2OF, is a member of the azo dye family. The dihedral angle subtended by the benzene ring and the naphthalene ring system measures 18.75 (7)°, indicating that the compound is not perfectly planar. An intra-molecular N-H⋯O hydrogen bond occurs between the imino and carbonyl groups. In the crystal, the mol-ecules are linked into inversion dimers by C-H⋯O inter-actions. Aromatic π-π stacking between the naphthalene ring systems lead to the formation of chains along [001]. A Hirshfeld surface analysis was undertaken to investigate and qu-antify the inter-molecular inter-actions. In addition, energy frameworks were used to examine the cooperative effect of these inter-molecular inter-actions across the crystal, showing dispersion energy to be the most influential factor in the crystal organization of the compound.

Prop-2-ynyl 3-meth-oxy-4-(prop-2-yn-yloxy)benzoate

The title compound, C14H12O4, comprises of two crystallographically independent mol-ecules in the asymmetric unit, linked via C-H⋯O inter-actions to form dimeric entities. The allylic groups are twisted out of the phenyl planes with dihedral angles varying between 7.92 (13) and 25.42 (8)°. In the crystal, the packing follows a zigzag pattern along the c-axis direction. The absolute configuration of the sample could not be determined reliably.

Discovery of highly functionalized grayanane diterpenoids from the flowers of Rhododendron molle as potent analgesics

A systematical investigation on the chemical constituents of the flowers of Rhododendron molle (Ericaceae) led to the isolation and characterization of thirty-eight highly functionalized grayanane diterpenoids (1-38), including twelve novel analogues molleblossomins A-L (1-12). Their structures were elucidated by comprehensive methods, including 1D and 2D NMR analysis, calculated ECD, 13C NMR calculations with DP4+ probability analysis, and single crystal X-ray diffraction. Molleblossomins A (1), B (2), and E (5) are the first representatives of 2β,3β:9β,10β-diepoxygrayanane, 2,3-epoxygrayan-9(11)-ene, and 5,9-epoxygrayan-1(10),2(3)-diene diterpenoids, respectively. Molleblossomins G (7) and H (8) represent the first examples of 1,3-dioxolane-grayanane conjugates furnished with the acetaldehyde and 4-hydroxylbenzylidene acetal moieties, respectively. All grayanane diterpenoids 1-38 were screened for their analgesic activities in the acetic acid-induced writhing model, and all of them exhibited significant analgesic activities. Diterpenoids 6, 13, 14, 17, 20, and 25 showed more potent analgesic effects than morphine at a lower dose of 0.2 mg/kg, with the inhibition rates of 51.4%, 68.2%, 94.1%, 66.9%, 97.7%, and 60.0%, respectively. More importantly, even at the lowest dose of 0.04 mg/kg, rhodomollein X (14), rhodojaponin VI (20), and rhodojaponin VII (22) still significantly reduced the number of writhes in the acetic acid-induced pain model with the percentages of 61.7%, 85.8%, and 64.6%, respectively. The structure-activity relationship was summarized and might provide some hints to design novel analgesics based on the functionalized grayanane diterpenoids.

trans-Di-chlorido-bis-[(S)-(-)-1-(4-methyl-phen-yl)ethyl-amine-κN]palladium(II)

The title complex, [PdCl2(C9H13N)2], comprises a single mol-ecule in the asymmetric unit. The PdII atom is tetra-coordinated by two N atoms from two trans-aligned organic ligands and two Cl ligands, forming a square-planar metal coordination environment. The distances from the ortho-H atoms on the phenyl ring to the central PdII atom fall within the range 4.70-5.30 Å, precluding any significant intra-molecular Pd⋯H inter-actions.

Bis(2-hy-droxy-2,3-di-hydro-1H-inden-1-aminium) tetra-chlorido-palladate(II) hemihydrate

A new square-planar palladium complex salt hydrate, (C9H12NO)2[PdCl4]·0.5H2O, has been characterized. The asymmetric unit of the complex salt comprises two [PdCl4]2- dianions, four 2-hy-droxy-2,3-di-hydro-1H-inden-1-aminium cations, each derived from (1R,2S)-(+)-1-amino-indan-2-ol, and one water mol-ecule of crystallization. In the crystal, a two-dimensional layer parallel to (001) features a number of O-H⋯O, N-H⋯O, O-H⋯Cl and N-H⋯Cl hydrogen bonds.

Crystal structure and Hirshfeld surface analysis of 3-benzyl-2-[bis(1H-pyrrol-2-yl)methyl]thiophene

In the title compound, C20H18N2S, the asymmetric unit comprises two similar mol-ecules (A and B). In mol-ecule A, the central thio-phene ring makes dihedral angles of 89.96 (12) and 57.39 (13)° with the 1H-pyrrole rings, which are bent at 83.22 (14)° relative to each other, and makes an angle of 85.98 (11)° with the phenyl ring. In mol-ecule B, the corresponding dihedral angles are 89.49 (13), 54.64 (12)°, 83.62 (14)° and 85.67 (11)°, respectively. In the crystal, mol-ecular pairs are bonded to each other by N-H⋯N inter-actions. N-H⋯π and C-H⋯π inter-actions further connect the mol-ecules, forming a three-dimensional network. A Hirshfeld surface analysis indicates that H⋯H (57.1% for mol-ecule A; 57.3% for mol-ecule B), C⋯H/H⋯C (30.7% for mol-ecules A and B) and S⋯H/H⋯S (6.2% for mol-ecule A; 6.4% for mol-ecule B) inter-actions are the most important contributors to the crystal packing.

X-ray crystallographic structure of a novel enantiopure chiral isothiourea with potential applications in enantioselective synthesis

The synthesis of a chiral isothiourea, namely, (4aR,8aR)-3-phenyl-4a,5,6,7,8,8a-hexahydrobenzo[4,5]imidazo[2,1-b]thiazol-9-ium bromide, C15H17N2S+·Br-, with potential organocatalytic and anti-inflammatory activity is reported. The preparation of the heterocycle of interest was carried out in two high-yielding steps. The hydrobromide salt of the isothiourea of interest provided suitable crystals for X-ray diffraction analysis, the results of which are reported. Salient observations from this analysis are the near perpendicular arrangement of the phenyl ring and the mean plane of the heterocycle. This conformational characteristic may be relevant with regard the stereoselectivity induced by the chiral isothiourea in asymmetric reactions. Furthermore, evidence was found for the existence of an S...Br- halogen bond.

(4-Butyl-1-ethyl-1,2,4-triazol-5-yl-idene)[(1,2,5,6-η)-cyclo-octa-1,5-diene](tri-phenyl-phosphane)rhodium(I) tetra-fluorido-borate

In the title triazole-based N-heterocyclic carbene rhodium(I) cationic complex with a tetra-fluorido-borate counter-anion, [Rh(C8H12)(C8H15N3)(C18H15P)]BF4, which crystallizes with two cations and two anions in the asymmetric unit, the Rh center has a distorted square-planar coordination geometry with expected bond distances. Several nonclassical C-H⋯F hydrogen-bonding inter-actions help to consolidate the packing. Two of the F atoms of one of the anions are disordered over adjacent sites in a 0.814 (4):0.186 (4) ratio.

Synthesis, crystal structure and properties of chlorido-tetra-kis-(pyridine-3-carbo-nitrile)-thio-cyanato-iron(II)

Reaction of FeCl2·4H2O with KSCN and 3-cyano-pyridine (pyridine-3-carbo-nitrile) in ethanol accidentally leads to the formation of single crystals of Fe(NCS)(Cl)(3-cyano-pyridine)4 or [FeCl(NCS)(C6H4N2)4]. The asymmetric unit of this compound consists of one FeII cation, one chloride and one thio-cyanate anion that are located on a fourfold rotation axis as well as of one 3-cyano-pyridine coligand in a general position. The FeII cations are sixfold coordinated by one chloride anion and one terminally N-bonding thio-cyanate anion in trans-positions and four 3-cyano-pyridine coligands that coordinate via the pyridine N atom to the FeII cations. The complexes are arranged in columns with the chloride anions, with the thio-cyanate anions always oriented in the same direction, which shows the non-centrosymmetry of this structure. No pronounced inter-molecular inter-actions are observed between the complexes. Initially, FeCl2 and KSCN were reacted in a 1:2 ratio, which lead to a sample that contains the title compound as the major phase together with a small amount of an unknown crystalline phase, as proven by powder X-ray diffraction (PXRD). If FeCl2 and KSCN is reacted in a 1:1 ratio, the title compound is obtained as a nearly pure phase. IR investigations reveal that the CN stretching vibration for the thio-cyanate anion is observed at 2074 cm-1, and that of the cyano group at 2238 cm-1, which also proves that the anionic ligands are only terminally bonded and that the cyano group is not involved in the metal coordination. Measurements with thermogravimetry and differential thermoanalysis reveal that the title compound decomposes at 169°C when heated at a rate of 4°C min-1 and that the 3-cyano-pyridine ligands are emitted in two separate poorly resolved steps. After the first step, an inter-mediate compound with the composition Fe(NCS)(Cl)(3-cyano-pyridine)2 of unknown structure is formed, for which the CN stretching vibration of the thio-cyanate anion is observed at 2025 cm-1, whereas the CN stretching vibration of the cyano group remain constant. This strongly indicates that the FeII cations are linked by μ-1,3-bridg-ing thio-cyanate anions into chains or layers.

Resolution by diastereomeric salts: Access to both enantiomers of racemic acid using the same enantiomer of resolving base

Racemic carboxylic acid, a Diels-Alder cycloadduct derived from 5-bromo-3-phenyl-α-pyrone and acrylate dienophile, was resolved into enantiomers by diastereomeric salt crystallization. Quinidine was used as a sole resolving base. The salt of (+)-acid crystallized from aqueous acetonitrile solution. Once this salt was separated by filtration, quinidine salt with (-)-acid crystallized from mother liquor. As a result, both enantiomers of Diels-Alder cycloadduct were isolated in high enantiomeric purity.

Synthesis, characterization, crystal structure and Hirshfeld surface analysis of isobutyl 4-[4-(di-fluoro-meth-oxy)phen-yl]-2,6,6-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxyl-ate

In the title compound, C24H29F2NO4, which crystallizes in the ortho-rhom-bic Pca21 space group with Z = 4, the 1,4-di-hydro-pyridine ring adopts a distorted boat conformation, while the cyclo-hexene ring is in a distorted half-chair conformation. In the crystal, the mol-ecules are linked by N-H⋯O and C-H⋯O inter-actions, forming supra-molecular chains parallel to the a axis. These chains pack with C-H⋯π inter-actions between them, forming layers parallel to the (010) plane. The cohesion of the crystal structure is ensured by van der Waals inter-actions between these layers. Hirshfeld surface analysis shows the major contributions to the crystal packing are from H⋯H (56.9%), F⋯H/H⋯F (15.7%), O⋯H/H⋯O (13.7%) and C⋯H/H⋯C (9.5%) contacts.

Three previously undescribed metabolites from Cordyceps cicadae JXCH-1, an entomopathogenic fungus

Three previously undescribed compounds, cordycicadione (1), cordycicadin F (2), and 7-hydroxybassiatin (3), were isolated from the cultures of Cordyceps cicadae JXCH1, an entomopathogenic fungus. Their structures and relative configurations were elucidated primarily by NMR spectroscopic analysis. The absolute configurations of 1 and 2 were determined by ECD calculations. Single-crystal X-ray diffraction method was adopted to determine the absolute configuration of 3. Compound 2 is a polycyclic polyketide with an unusual enol ether moiety and a spiro ring. The compounds obtained in this study were subjected to screening their inhibition against the proliferation of the human lung cancer cell line A549 and the production of nitric oxide in murine macrophages RAW264.7.

Host-guest system of a phosphorylated macrocycle assisting structure determination of oily molecules in single-crystal form

X-ray crystallography is the most reliable method for structure elucidation and absolute configuration determination of organic molecules based on their single-crystal forms. However, many analytes are hard to crystallize because of their low melting points (an oily state at room temperature) or conformational flexibility. Here, we report the crystallization of a macrocycle, CTX[P(O)Ph] (host), which is a cyclotrixylohydroquinoylene (CTX) derivative, with 26 oily organic molecules (guests), which is applied for the structural determination of the guest with X-ray crystallography. With the aid of the host, CTX[P(O)Ph], the guest molecules were well-ordered with full occupancy in crystal structures. In most cases, at least one guest structure without any disorder could be observed; solvent masking was not necessary for the single crystal X-ray structural analysis, and thus the structures of the guests could be successfully determined, and the absolute configuration could be assigned reliably for chiral guests with this method. The crystallization mechanism was further discussed from theoretical and experimental perspectives, suggesting that the negative electrostatic potential surface of CTX[P(O)Ph] and noncovalent interactions between the host and guest were crucial for the ordered arrangements of the guest.

Design, Synthesis, and Biological Evaluation of Novel Camphor-Based Hydrazide and Sulfonamide Derivatives as Laccase Inhibitors against Plant Pathogenic Fungi/Oomycetes

To discover novel natural product-based fungicidal agrochemicals, 41 novel camphanic acid hydrazide and camphor sulfonamide derivatives were designed, synthesized, and tested for their antifungal profile against four plant pathogenic fungi and three oomycetes. As a result, some derivatives presented pronounced inhibitory activities toward Botryosphaeria dothidea, Fusarium graminearum, Phytophthora capsici, and Phytophthora nicotianae. Especially, compound 4b demonstrated the most potent anti-B. dothidea activity (EC50 = 1.28 mg/L), much stronger than positive control chlorthalonil. The in vivo assay showed that 4b displayed significant protective and curative effects on apple fruits infected by B. dothidea. The primary antifungal mechanism study revealed that 4b could obviously enhance the cell membrane permeability, destroy the mycelial surface morphology and the cell ultrastructure, and reduce the ergosterol and exopolysaccharide contents of B. dothidea. Further, 4b showed potent laccase inhibitory activity in vitro with an IC50 value of 11.3 μM, superior to positive control cysteine. The molecular docking study revealed that 4b could dock well into the active site of laccase by forming multiple interactions with the key residues in the pocket. The acute oral toxicity test in rats presented that 4b had slight toxicity with an LD50 value of 849.1 mg/kg bw (95% confidence limit: 403.9-1785.3 mg/kg bw). This research identified that the camphanic acid hydrazide derivatives could be promising leads for the development of novel laccase-targeting fungicides.

Synthesis, crystal structure, Hirshfeld surface analysis, DFT and NBO study of ethyl 1-(4-fluoro-phen-yl)-4-[(4-fluoro-phen-yl)amino]-2,6-diphenyl-1,2,5,6-tetra-hydro-pyridine-3-carboxyl-ate

The title com-pound, C32H28F2N2O2, a highly functionalized tetra-hydro-pyridine, was synthesized by a one-pot multi-com-ponent reaction of 4-fluoro-aniline, ethyl aceto-acetate and benzaldehyde at room temperature using sodium lauryl sulfate as a catalyst. The com-pound crystallizes with two mol-ecules in the asymmetric unit. The tetra-hydro-pyridine ring adopts a distorted boat conformation in both mol-ecules and the dihedral angles between the planes of the fluoro-substituted rings are 77.1 (6) and 77.3 (6)°. The amino group and carbonyl O atom are involved in an intra-molecular N-H⋯O hydrogen bond, thereby generating an S(6) ring motif. In the crystal, mol-ecules are linked by C-H⋯F hydrogen bonds forming a three-dimensional network and C-H⋯π inter-actions. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H⋯H (47.9%), C⋯H/H⋯C (30.7%) and F⋯H/H⋯F (12.4%) contacts. The optimized structure calculated using density functional theory (DFT) at the B3LYP/6-311+G(2d,p) level is compared with the experimentally determined molecular structure in the solid state. The HOMO-LUMO behaviour was used to determine the energy gap and the Natural Bond Orbital (NBO) analysis was done to study donor-acceptor interconnections.

Cytotoxic tetronic acid derivatives from the mangrove endophytic fungus Hypomontagnella monticulosa YX702

Three new tetronic acid derivatives, nodulisporacid A ethyl ester (3), isosporothric acid methyl ester (4), and (R)-3-(methoxycarbonyl)-2-methyleneundecanoic acid (5) were isolated from mangrove endophytic fungus Hypomontagnella monticulosa YX702, together with three known analogues nodulisporacid A (1), nodulisporacid A methyl ester (2), and dihydrosporothriolide (6). The structures of these new compounds were elucidated by analysis of NMR and HR-ESI-MS spectroscopic data. In addition, the absolute configuration of nodulisporacid A (1) was confirmed by single-crystal X-ray diffraction for the first time. Subsequently, the absolute configuration of compounds 2 and 3 were determined by chemical derivatization of nodulisporacid A (1). The absolute configuration of compound 4 and 5 were established by TDDFT ECD calculations. Compounds 1 and 2 exhibited cytotoxic activities against A549 and Hela cancer cell lines with the IC50 values between 5.64 and 8.14 μM.

2-[4-(2-Chloro-benz-yl)-3-methyl-6-oxo-1,6-di-hydro-pyridazin-1-yl]-N-(4-fluoro-phen-yl)acetamide

The conformation of the title mol-ecule, C20H17ClFN3O2, is partly determined by an intra-molecular C-H⋯O hydrogen bond, which leads to a dihedral angle of 14.7 (4)° between the fluoro-benzene ring and the acetamide group. The 2-chloro-benzyl group is rotationally disordered over two orientations in a 0.656 (2): 0.344 (2) ratio. In the crystal, a layered structure is formed by N-H⋯O, C-H⋯O and C-H⋯F hydrogen bonds plus slipped π-π stacking inter-actions.

Poly[[[μ-1,4-bis-(pyridin-4-ylmeth-yl)piperazine][μ-4-(2-carboxyl-atoeth-yl)benzoato]copper(II)] monohydrate], a coordination polymer with twofold inter-penetrated cds topology networks

The title compound, {[Cu(C10H8O4)(C16H20N4)]·H2O}n, contains square-planar coordinated CuII ions linked by 4-(carboxyl-atoeth-yl)benzoato (ceb) and 1,4-bis-(pyridin-4-ylmeth-yl)piperazine (bpmp) ligands into a tri-periodic coordination polymer with twofold inter-penetrating 658 cds topology. Positional crystallographic disorder among the copper atoms, the ethyl-carb-oxy group of the ceb ligands, and the water mol-ecules of crystallization exists in a refined 0.655 (6)/0.345 (6) ratio.

Isomeric eremophilane lactones from the whole plant of Parasenecio albus and their cytotoxic and immunosuppressive activities

Ten previously unreported eremophilane lactones (parasalbolides A-J), including three pairs of C-10 epimers (parasalbolides A and G, B and H, and F and I, respectively), were isolated and identified from the whole plant of Parasenecio albus. Their structures were established on the basis of the HRESIMS and NMR spectroscopic analyses, combined with the comparison of the ECD spectra. The absolute configuration of parasalbolide A was confirmed by single-crystal X-ray diffraction using Cu Kα radiation. Parasalbolides A-J represent the first examples of 1,2,10-trioxygenated eremophila-7(11),8-dien-12,8-olides. The cytotoxic and immunosuppressive activities of selected isolates were evaluated and the (10S)-eremophilane lactones (parasalbolides A, B, and F) showed more potent activities than the (10R)-ones (parasalbolides G, H, and I).

Indium Kα radiation from a MetalJet X-ray source: comparison of the Eiger2 CdTe and Photon III detectors

The MetalJet source makes available new Kα radiation wavelengths for use in X-ray diffraction experiments. The purpose of this paper is to demonstrate the application of indium Kα radiation in independent-atom model refinement, as well as approaches using aspherical atomic form factors. The results vary greatly depending on the detector employed, as the energy cut-off of the Eiger2 CdTe provides a solution to a unique energy contamination problem of the MetalJet In radiation, which the Photon III detector cannot provide.

Factors Controlling Complex Morphologies of Isomorphous Metal-Organic Frameworks

We demonstrate here how nitrate salts of bivalent copper, nickel, cobalt, and manganese, along with an achiral organic ligand, assemble into various structures such as symmetrical double-decker flowers, smooth elongated hexagonal bipyramids, and hexagonal prisms. Large morphological changes occur in these structures because of different metal cations, although they maintain isomorphous hexagonal crystallographic structures. Metal cations with stronger coordination to ligands (Cu and Ni) tend to form uniform crystals with unusual shapes, whereas weaker coordinating metal cations (Mn and Co) produce crystals with more regular hexagonal morphologies. The unusual flower-like crystals formed with copper nitrate have two pairs of six symmetrical petals with hexagonal convex centers. The texture of the petals indicates dendritic growth. Two different types of morphologies were formed by using different copper nitrate-to-ligand ratios. An excess of the metal salt results in uniform and hexagonal crystals having a narrow size distribution, whereas the use of an excess of ligand results in double-decker morphologies. Mechanistically, an intermediate structure was observed with slightly concave facets and a domed center. Such structures most likely play a key role in the formation of double-decker crystals that can be formed by fusion processes. The coordination chemistry results in isostructural chiral frameworks consisting of two types of continuous helical channels. Four pyridine units from four separate ligands are coordinated to the metal center in a plane having a chiral (propeller-type) arrangement. The individual double-decker flower crystals are homochiral and a batch consists of crystals having both handedness.

Inert Transition Metal Ion Complexes in Organic Synthesis: Protection and Activation

Single-crystal X-ray diffraction studies for a variety of metal ion complexes of functionalised sarcophagines (sarcophagine=sar=3,6,10,13,16,19-hexa-azabicyclo[6.6.6]icosane) have further confirmed not only that the form of the metal ion/sar unit is unique for each metal, albeit with a sensitivity of the conformation to the associated counter anions, but also that for any given metal and ligand substituent, the dimensions (bond lengths and angles) of the complex and the substituent at the secondary nitrogen centres do not differ significantly from those of the isolated components. Despite this, where the substituent contains reactive sites, the reactivity differs markedly from that of their form in an uncoordinated substrate. Rationalisations are offered for these differences, in part through the use of Hirshfeld surface analysis of the intermolecular interactions. The kinetic inertness of the complexes means that the metal ions can be considered to act as regioselective protecting groups.

3-Nitro-benzo-nitrile

The crystal structure of 3-nitrobenzonitrile, C7H4N2O2, was elucidated by low-temperature single-crystal X-ray diffraction. The compound crystallizes in the Sohncke space group P21 and features two mol-ecules in the unit cell. Aromatic π-π stacking leads to stacks of mol-ecules in the [100] direction. The absolute structure was established from anomalous dispersion.

Synthesis, characterization and crystal structure of methyl 2-(2-oxo-2H-chromen-4-yl-amino)-benzoate

Methyl 2-(2-oxo-2H-chromen-4-yl-amino)-benzoate, C17H13NO4 (1), was pre-pared by condensation between 4-hy-droxy-coumarin and methyl 2-amino-benzoate. It crystallizes in the ortho-rhom-bic space group Pca21 at 300 K. The mol-ecule of compound 1 consists of the 2H-chromen-2-one part connected by an amine moiety (-NH-) to the methyl benzoate ring. The supra-molecular array is formed by hydrogen bonds between the aromatic ring and the O atoms of the lactone and ester portions. The structural details match the spectroscopic data acquired from NMR and IR spectroscopy.

Optimal estimated standard uncertainties of reflection intensities for kinematical refinement from 3D electron diffraction data

Estimating the error in the merged reflection intensities requires a full understanding of all the possible sources of error arising from the measurements. Most diffraction-spot integration methods focus mainly on errors arising from counting statistics for the estimation of uncertainties associated with the reflection intensities. This treatment may be incomplete and partly inadequate. In an attempt to fully understand and identify all the contributions to these errors, three methods are examined for the correction of estimated errors of reflection intensities in electron diffraction data. For a direct comparison, the three methods are applied to a set of organic and inorganic test cases. It is demonstrated that applying the corrections of a specific model that include terms dependent on the original uncertainty and the largest intensity of the symmetry-related reflections improves the overall structure quality of the given data set and improves the final Rall factor. This error model is implemented in the data reduction software PETS2.

Diastereotopic groups in two new single-enanti-omer structures (R2)P(O)[NH-(+)CH(C2H5)(C6H5)] (R = OC6H5 and C6H5)

The crystal structures of two single-enanti-omer compounds, i.e. diphenyl [(R)-(+)-α-ethyl-benzyl-amido]-phosphate, C21H22NO3P or (C6H5O)2P(O)[NH-(R)-(+)CH(C2H5)(C6H5)] (I), and N-[(R)-(+)-α-ethyl-benz-yl]-P,P-di-phenyl-phosphinic amide, C21H22NOP or (C6H5)2P(O)[NH-R-(+)CH(C2H5)(C6H5)] (II), were studied. The different environments at the phospho-rus atoms, (O)2P(O)(N) and (C)2P(O)(N), allow the P=O/P-N bond strengths to be compared, as well as the N-H⋯O=P hydrogen-bond strengths, and P=O/N-H vibrations. The following characteristics related to diastereotopic C6H5O/C6H5 groups in I/II were considered: geometry parameters, contributions to the crystal packing, solution 13C/1H NMR chemical shifts, conformations, and NMR coupling constants. The phospho-rus-carbon coupling constants nJ PC (n = 2 and 3) in I and mJ PC (m = 1, 2, 3 and 4) in II were evaluated. For a comparative study, chiral analogous structures were retrieved from the Cambridge Structural Database (CSD) and their geometries and conformations are discussed.

Accurate X-ray diffraction data required for proper evaluation of bond valence sums and global instability indexes: redetermination of the crystal structures of diamond-like Cu2CdSiS4 and Cu2HgSnS4 as a case study

Our calculations of the global instability index (G) values for some diamond-like materials with the general formula I2-II-IV-VI4 have indicated that the structures may be unstable or incorrectly determined. To compute the G value of a given compound, the bond valence sums (BVSs) must first be calculated using a crystal structure. Two examples of compounds with high G values, based on data from the literature, are the wurtz-stannite-type dicopper cadmium silicon tetrasulfide (Cu2CdSiS4) and the stannite-type dicopper mercury tin tetrasulfide (Cu2HgSnS4), which were first reported in 1967 and 1965, respectively. In the present study, Cu2CdSiS4 and Cu2HgSnS4 were prepared by solid-state synthesis at 1000 and 900 °C, respectively. The phase purity was assessed by powder X-ray diffraction. Optical diffuse reflectance UV/Vis/NIR spectroscopy was used to estimate the optical bandgaps of 2.52 and 0.83 eV for Cu2CdSiS4 and Cu2HgSnS4, respectively. The structures were solved and refined using single-crystal X-ray diffraction data. The structure type of Cu2CdSiS4 was confirmed, where Cd2+, Si4+ and two of the three crystallographically unique S2- ions lie on a mirror plane. The structure type of Cu2HgSnS4 was also verified, where all ions lie on special positions. The S2- ion resides on a mirror plane, the Cu+ ion is situated on a fourfold rotary inversion axis and both the Hg2+ and the Sn4+ ions are located on the intersection of a fourfold rotary inversion axis, a mirror plane and a twofold rotation axis. Using the crystal structures solved and refined here, the G values were reassessed and found to be in the range that indicates reasonable strain for a stable crystal structure. This work, together with some examples gathered from the literature, shows that accurate data collected on modern instrumentation should be used to reliably calculate BVSs and G values.

The synthesis and characterization of a series of cocrystals of an isoniazid derivative with butan-2-one and propan-2-one

Four cocrystals containing N'-(butan-2-ylidene)pyridine-4-carbohydrazide (izbt) and one cocrystal containing N'-isopropylideneisonicotinohydrazide (izact) were synthesized by reacting isoniazid with either butan-2-one (for the former) or acetone (for the latter). The coformers used to synthesize the izbt cocrystals were 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2-chloro-4-nitrobenzoic acid and 1-naphthoic acid. 1-Naphthoic acid was also used with izact to form a cocrystal. The 1:1 cocrystals are: N'-(butan-2-ylidene)pyridine-4-carbohydrazide-1-naphthoic acid (izbt-1nta), C10H13N3O·C11H8O2, N'-(butan-2-ylidene)pyridine-4-carbohydrazide-2,4-dihydroxybenzoic acid (izbt-2,4-dhba), C10H13N3O·C7H6O4, N'-(propan-2-ylidene)pyridine-4-carbohydrazide-1-naphthoic acid (izact-1nta), C9H11N3O·C11H8O2, N'-(butan-2-ylidene)pyridine-4-carbohydrazide-2-chloro-4-nitrobenzoic acid (izbt-2c4n), C10H13N3O·C7H4ClNO4, and N'-(butan-2-ylidene)pyridine-4-carbohydrazide-2,5-dihydroxybenzoic acid (izbt-2,5-dhba), C10H13N3O·C7H6O4. The cocrystals containing izbt were compared to those containing the same (or similar) coformers with izact that have been reported either here or in the Cambridge Structural Database (CSD). Most of the cocrystals showed different packing despite having the same hydrogen-bonding motifs. The cocrystals were characterized by single-crystal X-ray diffraction (SC-XRD), powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC).

Hemilability and structural considerations in complexes of platinum(II) comprising bis(diphenylphosphanyl)methane monoxide, monosulfide, and monoselenide

The structure of a platinum(II) complex containing (R)-(dimethylamino)ethylnapthyl and bis(diphenylphosphanyl)methane monosulfide ligands, namely, {(R)-1-[1-(dimethylamino)ethyl]napthyl-κ2N,C2}[(diphenylphosphanylmethyl)diphenylphosphine sulfide-κ2P,S]platinum(II) hexafluoridoantimonate dichloromethane monosolvate, [Pt(C14H16N)(C25H22P2S)][SbF6]·CH2Cl2, was determined. The structural features are compared with analogous platinum bis(diphenylphosphanyl)methane monoxide [dppm(O)] and bis(diphenylphosphanyl)methane monoselenide [dppm(Se)] complexes in relation to their potential hemilability and stereochemical nonrigidity.

Crystal structure of the nucleoside 2'-de-oxy-guanosine dimethyl sulfoxide disolvate

The title com-pound, C10H13N5O4·2C2H6OS, which is of inter-est with respect to its biological activity, at 183 K has ortho-rhom-bic (P212121) crystal symmetry. The structure displays a network of inter-molecular N-H⋯N, N-H⋯O and O-H⋯O hydrogen bonds. 2'-De-oxy-guanosine mol-ecules are linked to each other and to the two dimethyl sulfoxide solvent mol-ecules by hydrogen bonding.

3-Ferrocenyl-estra-1,3,5 (10)-triene-17-one: Synthesis, Crystal Structure, Hirshfeld Surface Analysis, DFT Studies, and Its Binding to Human Serum Albumin Studied through Fluorescence Quenching and In Silico Docking Studies

3-ferrocenyl-estra-1,3,5 (10)-triene-17-one (2), [Fe(C5H5)(C24H25O3)], crystallizes in the monoclinic space group C2. The cyclopentadienyl (Cp) rings adopt a nearly eclipsed conformation, and the Cp plane is tilted by 87.66° with respect to the substituted phenyl plane. An average Fe-C(Cp) bond length of 2.040(13) Å was determined, similar to the one reported for ferrocene. Hirshfeld surfaces and two-dimensional fingerprint plots were generated to analyze weak intermolecular C-H···π and C-H···O interactions. Density functional theory studies revealed a 1.15 kcal/mol rotational barrier for the C3-O1 single bound. Fluorescence quenching studies and in silico docking studies suggest that human serum albumin forms a complex with 2 via a static mechanism dominated by van der Waals interactions and hydrogen bonding interactions.

5-Fluoro-3-(1H-indol-3-ylmeth-yl)-1H-indole

The title compound, C17H13FN2, was synthesized as a potential ligand for the construction of metal-organic frameworks. The two indole motifs present two potential coordination modes. It crystallizes in the ortho-rhom-bic system with space group P212121. The dihedral angle between the fused ring systems is 68.77 (10)°. Weak F⋯H inter-actions are observed in the crystal.

Diethyl 2,2'-[({2-chloro-5-[(2-eth-oxy-2-oxoeth-yl)(2-methyl-indolin-1-yl)carbamo-yl]phen-yl}sulfon-yl)aza-nedi-yl]di-acetate

The majority of the title mol-ecule, C28H34ClN3O9S, is disordered over two closely spaced sets of sites; the site occupancy of the major component = 0.542 (3). The conformation of each component is approximately U-shaped with the chloro-benzene ring forming the base and the indolinyl and sulfamoyl groups the sides; an intra-molecular C-H⋯Cl hydrogen bond possibly contributes to the stabilization of the conformation. In the crystal, a corrugated layer structure parallel to the ab plane is formed by C-H⋯O and C-H⋯Cl hydrogen bonds together with C-H⋯π(ring) inter-actions.

Resolving a Natural Product Cold Case: Elucidation of Fusapyrone Structure and Absolute Configuration and Demonstration of Their Fungal Biofilm Disrupting Properties

Fusapyrones are fungal metabolites, which have been reported to have broad-spectrum antibacterial and antifungal properties. Despite the first members of this chemical class being described three decades prior, many aspects of their structures have remained unresolved, thereby constraining efforts to fully understand structure-activity relationships within this metabolite family and impeding the design of streamlined syntheses. Among the main challenges posed by fusapyrones is the incorporation of several single and groups of stereocenters separated by atoms with freely rotating bonds, which have proven unyielding to spectroscopic analyses. In this study, we obtained a series of new (2-5 and 7-9) and previously reported fusapyrones (1 and 6), which were subjected to a combination of spectroscopic, chemical, and computational techniques enabling us to offer proposals for their full structures, as well as provide a pathway to reinterpreting the absolute configurations of other published fusapyrone metabolites. Biological testing of the fusapyrones revealed their abilities to inhibit and disrupt biofilms made by the human fungal pathogen, Candida albicans. These results show that fusapyrones reduce hyphae formation in C. albicans, as well as decrease the surface adherence capabilities of planktonic cells and cells transitioning into early-stage biofilm formation.

Spontaneous Chiral Resolution of a MnIII Spin-Crossover Complex with High Temperature 80 K Hysteresis

Non-centrosymmetric spin-switchable systems are of interest for their prospective applications as magnetically active non-linear optical materials and in multiferroic devices. Chiral resolution of simple spin-crossover chelate complexes into the Δ and Λ forms offers a facile route to homochiral magnetic switches, which could be easily enantiomerically enriched. Here, we report the spontaneous resolution of a new hysteretic spin-crossover complex, [MnIII (sal2 323)]SCN ⋅ EtOH (1), into Δ and Λ forms, without the use of chiral reagents, where sal2 323 is a Schiff base resulting from condensation of 1,2-bis(3-aminopropylamino)ethane with 2-hydroxybenzaldehyde. The enantiopurity of the Δ and Λ isomers was confirmed by single crystal X-ray diffraction and circular dichroism. Quantum chemistry calculations were used to investigate the electronic structure. The opening of a wide 80 K thermal hysteresis window at high temperature highlights the potential for good magneto-optical function at ambient temperature for materials of this type.

Oxepine-containing pyrazinopyrimidine alkaloids and quinolinone derivatives produced by Aspergillus versicolor AS-212, a deep-sea-derived endozoic fungus

Four new oxepine-containing pyrazinopyrimidine alkaloids, versicoxepines A - D (1-4), two quinolinone alkaloid analogs including 3-hydroxy-6-methoxy-4-phenylquinolin-2(1H)-one (5) and 3-methoxy-6-hydroxy-4-phenylquinolin-2(1H)-one (6) which were new naturally occurring compounds, together with two known compounds (7 and 8) were isolated from Aspergillus versicolor AS-212, an endozoic fungus isolated from the deep-sea coral Hemicorallium cf. imperiale, which was collected from the Magellan Seamounts in the Western Pacific Ocean. Their structures were determined by extensive analysis of the spectroscopic and X-ray crystallographic data as well as by chiral HPLC analysis, ECD calculation, and DP4+ probability prediction. Structurally, versicoxepines B and C (2 and 3) represent the first example of a new oxepine-containing pyrazinopyrimidine alkaloid whose cyclic dipeptide moiety is composed of the same type of amino acid (Val or Ile). Compound 5 displayed antibacterial activity against aquatic pathogens, Vibrio harveyi and V. alginolyticus, with MICs of 8 μg/mL.

Synthesis, optical properties and crystal structure of (E,E)-1,3-(3,4:9,10-dibenzododeca-1,11-diene-5,7-diyne-1,12-di-yl)benzene

The de-hydro-benzannulene (E,E)-1,3-(3,4:9,10-dibenzododeca-1,11-diene-5,7-diyne-1,12-di-yl)benzene, C26H16, was successfully synthesized via photocatalyst-assisted stereoselective reductive de-sulfonyl-ation of 1,3-bis-{1-phenyl-sulfonyl-2-[2-(tri-methyl-silylethyn-yl)phen-yl]ethen-yl}benzene, C44H42O4S2Si2, and subsequent desilylative cyclization of the resulting (E,E)-bis-silyl-protected dienyne, C32H34Si2. The structure of the de-hydro-benzannulene thus obtained was confirmed by single-crystal X-ray analysis; three benzene rings are connected to one another by a 1,3-butadiynylene and a pair of ethenylene arrays. Although the π-system expanded efficiently in the de-hydro-benzannulene, it was observed that the butadiynylene and ethenylene arrays were strained, showing smaller [171.3 (2)-172.6 (2) °] and larger bond angles [122.5 (2)-131.9 (2)°] than the conventional bond angles, respectively. In CHCl3, the de-hydro-benzannulene showed the longest absorption band at 377 nm. When irradiated by UV light, it emitted fluorescence at 468 nm (ΦF = 0.26) and 504 nm (ΦF = 0.24) in CHCl3 and in the powdered state, respectively.

4-Oxo-N-phenyl-1,4-di-hydro-pyridine-3-carboxamide

The title compound, C12H10N2O2, shows a nearly planar conformation. The crystal structure is sustained by hydrogen bonds between the NH and the carbonyl O function of the 4-oxo-1,4-di-hydro-pyridine ring of the mol-ecules, forming infinite chains along the b-axis direction.