Pefloxacinium methane­sulfonate 0.10‐hydrate

The crystal structure of 4‐(3‐carboxy‐1‐ethyl‐6‐fluoro‐1,4‐di­hydro‐4‐oxo‐7‐quinolyl)‐1‐methyl­piperazinium methane­sulfonate 0.10‐hydrate, C₁₇H₂₁FN₃O₃⁺·CH₃O₃S^?·0.10H₂O, contains pefloxacinium cations, methane­sulfonate anions and a partially occupied water of solvation. The quinoline ring system in the cation is essentially planar. The anions lie parallel to each other about inversion centers. The structure is stabilized by strong hydrogen bonds involving the terminal piperazinyl‐N atom of the cation and an O atom of the anion [N?O 2.739 (2) Å], and a strong intramolecular hydrogen bond between carbonyl and carboxyl groups [O?O 2.523 (2) Å].     

Tetra­aqua(5‐fluoro­uracil‐1‐acetato‐O)copper(II) tetra­hydrate

In the title complex, [Cu(C₆H₄FN₂O₄)₂(H₂O)₄]·4H₂O, the Cu atom is located in the centre of a distorted octahedral geometry. The coordination atoms are six O atoms provided by two carboxyl­ate groups [coordinated in a monodentate mode, with Cu—O = 1.9551 (10) Å] and four water mol­ecules [Cu—O = 1.9241 (13) and 2.5771 (14) Å]. In addition, one intramolecular hydrogen bond and ten intermolecular hydrogen bonds make up a three‐dimensional network.     

Dimorphism in 3′‐amino­cyclo­hexane­spiro‐5′‐hydantoin

The title compound [systematic name: 1′‐amino­cyclo­hexane­spiro‐4′‐imidazole‐2′,5′(3′H,4′H)‐dione], C₈H₁₃N₃O₂, has been synthesized and was found to crystallize in two different structures, both monoclinic and both with the same P2₁/c space group. In the first structure, there are two mol­ecules in the asymmetric unit, one of which uses all of its hydrogen‐bond donors and acceptors and forms undulating layers, while the other forms chains propagating perpendicular to the layers. In the second structure, there is only one independent mol­ecule and the packing is based on a chain structure mediated by hydrogen bonding between the hydantoin moieties and further grouped into hydro­philic layers separated by layers of the hydro­phobic cyclo­hex­yl groups.     

Three 2‐amino­purine derivatives

The structure of 2‐amino‐6‐chloro­purine, C₅H₄ClN₅, (I), comprises a flat mol­ecule, with all possible strong hydrogen‐bond donors and acceptors involved in the hydrogen‐bonding network. The structures of 2‐amino‐6‐(4‐chloro­phenylsulfanyl)­purine hemihydrate, C₁₁H₈ClN₅S·0.5H₂O, (II), and 2‐amino‐6‐(4‐methylphenylsulfanyl)purine 0.33‐hydrate, C₁₂H₁₁N₅S·0.33H₂O, (III), have two and three unique mol­ecules, respectively, and one water mol­ecule in their asymmetric units. Both (II) and (III) exhibit elaborate hydrogen‐bonding networks that involve the S (for both) and Cl [for (II)] atoms in addition to the expected strong hydrogen‐bonding sites. Both structures also have offset‐stacking formations of the phenyl and purine rings.     

Two derivatives of 5‐amino­tetrazole: 5‐amino‐1‐phenyl­tetrazole and 5‐amino‐1‐(1‐naphthyl)­tetrazole

In the mol­ecules of 5‐amino‐1‐phenyl­tetrazole, C₇H₇N₅, (I), and 5‐amino‐1‐(1‐naphthyl)­tetrazole, C₁₁H₉N₅, (II), the tetrazole rings and aryl fragments are not coplanar; corresponding dihedral angles are 50.58 (5) and 45.19 (7)° for the two independent mol­ecules of (I), and 64.14 (5)° for (II). Intermolecular N—H⋯N hydrogen bonds between the amino groups and tetrazole N atoms are primarily responsible for formation of two‐dimensional networks extending parallel to the bc plane in both compounds. The presence of the amino group has a distinct effect on the geometry of the tetrazole rings in each case.     

trans‐4‐[(4‐Di­methyl­amino­phenyl)­imino­methyl]‐N‐methyl­pyridinium para‐toluene­sulfonate

In the title compound, C₁₅H₁₈N₃⁺·C₇H₇O₃S^?, the phenyl­ene and pyridyl rings are somewhat twisted with respect to each other, forming a dihedral angle of 23.49 (6)°. The compound contains a dipolar chromophoric cation, but crystallizes in the centrosymmetric space group P2₁/n and is thus not expected to display quadratic non‐linear optical effects.     

A simple compound with an ­unexpectedly complex structure: 4‐pyridone 6/5‐hydrate

The crystal structure of the title compound, C₅H₅NO·H₂O, contains five independent mol­ecules of pyridone and six independent water mol­ecules. The space group is P2₁, but four of the pyridones and four waters correspond closely to P2₁/n. The packing involves two layers; one consists of head‐to‐tail chains of pyridone mol­ecules 1–4 linked by N—H?O hydrogen bonds, and a second layer involves all the waters and the fifth pyridone. The layers are linked by hydrogen bonds from water to pyridone oxy­gen. The four water O atoms that accept only one classical hydrogen bond have their environment completed by C—H?O interactions.     

2‐Amino­thia­zole and 2‐amino­thiazolinone derivatives

The reaction of different substituted α‐cyano­oxiranes with thio­urea resulted in the formation of the 2‐amino­thia­zolinone derivative 2‐amino‐5‐(2,5‐di­methoxy­phenyl)‐1,3‐thia­zol‐4(5H)‐one, C₁₁H₁₂N₂O₃S, (I), and the 2‐amino­thia­zole derivative ethyl 2‐amino‐5‐(2,5‐di­methoxy­phenyl)‐1,3‐thia­zole‐4‐carboxyl­ate, C₁₄H₁₆N₂O₄S, (II). The geometries of the two crystallographically independent mol­ecules in (II) are nearly identical but mirror related. The crystal structures of both compounds contain two types of intermolecular hydrogen bonds.     

Hexaaqua­nickel(II) bis­(4′,7‐dimethoxy­isoflavone‐3′‐sulfonate) octa­hydrate

In the title compound, [Ni(H₂O)₆](C₁₇H₁₃O₇S)₂·8H₂O, the Ni^II atom is located on an inversion centre in the space group P2₁/c. The [Ni(H₂O)₆]²⁺, C₁₇H₁₃O₇S⁻ and H₂O components form many hydrogen bonds and there are π–π stacking inter­actions betweeen the isoflavone units. The hydrogen bonds, π–π stacking inter­actions and electrostatic inter­actions between the cation and anions link the components into a three‐dimensional structure.     

4‐Di­methyl­amino­pyridinium bromide

The crystal and molecular structure of 4‐di­methyl­amino­pyridinium bromide, C₇H₁₁N₂^+.Br^?, (I), is built up by hydrogen‐bonded dimers of crystallographic 222 symmetry and four short C—H...halogen contacts. It is remarkable that (I) and 4‐di­methyl­amino­pyridinium chloride are not isostructural.     

Hexaquacobalt(II) bis(5‐hydroxy‐7‐methoxy‐4‐oxo‐2‐phenyl‐4H‐chromene‐6‐sulfonate) tetrahydrate

The title compound, [Co(H₂O)₆](C₁₆H₁₁O₇S)₂·4H₂O, with cobalt(II) at the centre of symmetry, exhibits alternating hydrophilic and hydrophobic regions. Hydrophilic regions are generated by O—H...O hydrogen bonds among sulfonate groups, involving solvent water molecules and coordinated water molecules; π–π stacking interactions assemble the flavone skeletons into columns which form the hydrophobic regions. A three‐dimensional network is built up from an extensive array of hydrogen bonds, π–π stacking interactions and electrostatic interactions between the cation and anion. As a salt of the sulfonated derivative of naturally occurring tectochrysin (5‐hydroxy‐7‐methoxyflavone), this compound offers enhanced solubility and potential biological activity over the natural product.     

Sodium 2‐oxo‐3‐semicarbazono‐2,3‐dihydro‐1H‐indole‐5‐sulfonate dihydrate

The title compound, Na⁺·C₉H₇N₄O₅S⁻·2H₂O, presents a Z configuration around the imine C=N bond and an E configuration around the C(O)NH₂ group, stabilized by two intra­molecular hydrogen bonds. The packing is governed by ionic inter­actions between the Na⁺ cation and the surrounding O atoms. The ionic unit, Na⁺ and 2‐oxo‐3‐semicarbazono‐2,3‐dihydro‐1H‐indole‐5‐sulfonate, forms layers extending in the bc plane. The layers are connected by hydrogen bonds involving the water mol­ecules.     

Three 4‐amino­quinolines of anti­malarial interest

The structures of three compounds with potential anti­malarial activity are reported. In N,N‐diethyl‐N′‐(7‐iodo­quinolin‐4‐yl)ethane‐1,2‐diamine, C₁₅H₂₀IN₃, (I), the mol­ecules are linked into ribbons by N—H⋯N and C—H⋯N hydrogen bonds. In N‐(7‐bromo­quinolin‐4‐yl)‐N′,N′‐diethyl­ethane‐1,2‐diamine dihydrate, C₁₅H₂₀BrN₃·2H₂O, (II), two amino­quino­line mol­ecules and four water mol­ecules form an R₅⁴(13) hydrogen‐bonded ring which links to its neighbours to form a T5(2) one‐dimensional infinite tape with pendant hydrogen bonds to the amino­quinolines. The phosphate salt 7‐chloro‐4‐[2‐(diethyl­ammonio)ethyl­amino]quinolinium bis­(dihydrogen­phosphate) phospho­ric acid, C₁₅H₂₂ClN₃²⁺·2H₂PO₄⁻·H₃PO₄, (III), was prepared in order to establish the protonation sites of these compounds. The phosphate ions form a two‐dimensional hydrogen‐bonded sheet, while the amino­quino­line cations are linked to the phosphates by N—H⋯O hydrogen bonds from each of their three N atoms. While the conformation of the quinoline region hardly varies between (I), (II) and (III), the amino side chain is much more flexible and adopts a significantly different conformation in each case. Aromatic π–π stacking inter­actions are the only supramolecular inter­actions seen in all three structures.     

()‐5‐(4‐Methoxy­phenyl­amino­carbonyl)‐1‐aza­bi­cyclo­[3.3.0]octan‐2‐one benzene solvate

The title trans prolyl amide exists as a benzene solvate, C₁₅H₁₈N₂O₃·C₆H₆, with positional disorder of the prolyl ring. The molecular structure is influenced by a close intramolecular N—H⋯N contact that provides structural support for the intramolecular catalysis of peptidyl–prolyl cis–trans isomerization.     

Syntheses of 5‐Hexadecanolide, 6‐Acetoxy‐5‐hexadecanolide and Tanikolide

Total syntheses of 5‐hexadecanolide ( 1 ), 6‐acetoxy‐5‐hexadecanolide ( 2 ) and tanikolide ( 3 ) are described. 1‐Bromoundecane ( 4 ) and 5‐benzyl‐1‐pentanal ( 5 ) were chosen as starting materials. Wittig olefination and Grignard addition 4 and 5 afforded the 16‐carbon skeleton, which under went a series of functional group transformations to give δ‐lactonederivatives 1, 2 and 3.     

Di­methyl (1‐methyl‐1,3‐benzimidazol‐5‐yl)­amino­methyl­ene­propane­dioate monohydrate

In the title compound, C₁₄H₁₅N₃O₄·H₂O, there is a strong conjugation push–pull effect across the central double bond, as reflected in the molecular dimensions and the planarity of the en­amino­ne portion of the mol­ecule. The mol­ecule has an intramolecular hydrogen bond between the NH and CO groups in the Z configuration, adopting the chelated form. The two π systems of the mol­ecule (1‐methyl­benz­imidazole and en­amino­ne) are deconjugated and tilted with respect to each other by 15.6 (2)°. The solvent water mol­ecule is hydrogen bonded to the N¹ atom of the 1‐methyl­benzimidazolyl group.     

Bis­(saccharinato‐κN)zinc(II) com­plexes with N,N′‐bidentate 2‐amino­methyl­pyridine and 2‐amino­ethylpyridine

The structures of trans‐bis[2‐(amino­methyl)­pyridine‐κ²N,N′]­bis­(saccharinato‐κN)­zinc(II), [Zn(C₇H₄NO₃S)₂(C₆H₈N₂)₂], (I), and [2‐(amino­ethyl)­pyridine‐κ²N,N′]bis­(saccharinato‐κN)­zinc(II), [Zn(C₇H₄NO₃S)₂(C₇H₁₀N₂)], (II), exhibit octa‐ and tetrahedrally coordinated Zn^II atoms, respectively. The di­amine ligands behave as N,N′‐bidentate ligands, while saccharinate (sac) is coordinated through the N atom. In (I), the complex lies about an inversion centre with the Zn atom disordered and displaced by 0.256 (2) Å from a centre of symmetry towards a sac N atom. The crystal structure of (I) is stabilized by N—H⋯O hydrogen bonds and the crystal packing of (II) is determined by hydrogen bonding as well as weak π–π stacking interactions between the sac ligands.     

[N,N′‐Bis(5‐bromo­salicyl­idene)‐1,3‐di­amino­propane]­nickel(II) and [N,N′‐­bis(5‐chloro­salicyl­idene)‐1,3‐­di­amino­propane]copper(II)

The title compounds, {4,4′‐di­bromo‐2,2′‐[1,3‐propane­diyl­bis(nitrilo­methyl­idyne‐N)]­diphenolato‐O,O′}nickel(II), [Ni(C₁₇­H₁₄­Br₂­N₂O₂)], and {4,4′‐di­chloro‐2,2′‐[1,3‐pro­pane­diyl­bis­(ni­trilo­methyl­idyne‐N)]­di­phen­ol­ato‐O,O′}­copper(II), [Cu­(C₁₇­H₁₄­Cl₂­N₂O₂)], lie on crystallographic twofold axes. In both structures, the metal coordination sphere is a tetrahedrally distorted square plane formed by the four‐coordinate N₂O₂ donor set of the Schiff base imine–phenol ligands. In the Ni compound, the Ni—O and Ni—N distances are 1.908 (3) and 1.959 (4) Å, respectively, while in the Cu compound, the Cu—O and Cu—N distances are 1.907 (2) and 1.960 (2) Å, respectively. The two Schiff base moieties, which themselves are nearly planar, are inclined at an angle of 29.26 (7)° for the Ni compound and 29.26 (5)° for the Cu compound.     

Benzyl tert‐but­oxy­carbonyl‐α‐amino­isobutyrate

The small synthetic peptide, benzyl 2‐(tert‐but­oxy­carbonyl‐amino)­isobutyrate, C₁₆H₂₃NO₄, has the α‐helical conformation [|?| = 55.8 (2)° and |ψ| = 37.9 (2)°] observed in peptide fragments of peptaibols containing the α‐amino­isobutyric acid (Aib) residue. The structure shows no intramolecular hydrogen bonding, which would disrupt the limited conformational freedom associated with this amino acid. Two weak intermolecular hydrogen contacts are observed.     

5‐Methyl‐6‐aza‐2′‐deoxy­isocytidine

In the title compound, 3‐amino‐2‐(2‐deoxy‐β‐d ‐erythro‐pento­furan­osyl)‐6‐methyl‐1,2,4‐triazin‐5(2H)‐one, C₉H₁₄N₄O₄, the conformation of the N‐glycosidic bond is high‐anti and the 2‐deoxy­ribo­furan­osyl moiety adopts a North sugar pucker (²T₃). The orientation of the exocyclic C—C bond between the –CH₂OH group and the five‐membered ring is ap (gauche, trans). The crystal packing is such that the nucleobases lie parallel to the ac plane; the planes are connected via hydrogen bonds involving the five‐membered ring.