Synthesis,characterization, and antibacterial activity of 6-Chloro-8-methyl-2-oxo-2H-chromene-3-carboxylic acid ethyl ester

The title compound was synthesized by reacting 2-hydroxy-4-methoxy-benzaldehyde with diethyl malonate in the presence of piperidine catalyst and ethanol as solvent. The chemical structure of the title compound was elucidated by elemental analysis, ¹H-NMR, and IR. The crystal structure was determined by X-ray diffraction data. It crystallizes in monoclinic crystal system, P2₁/c space group with unit cell parameters, a = 12.840(2) Å, b = 24.790(4) Å, c = 7.8544(13) Å, β = 98.035(5)°, V = 2475.5(7) ų, and Z = 8. The molecular and crystal structure of the title compound is stabilized by inter- and intramolecular interactions of the type C—H···O. The newly synthesized compound was screened for its antibacterial activity against two gram-positive and two gram-negative bacteria.     

The molecular and crystal structure of 2-oxo-1-pyrrolidine-acetamide

C₆H₁₀N₂O₂, P1 , a = 6,607(2) Å, b = 8,538(2) Å, c = 6,392(2) Å, α = 102,43(2)°, β = 91,11(2)°, y = 79,82(2)°, V = 349,1 ų, Z = 2, D_m = 1,36 g × cm⁻³, D_x = 1,35 g × × cm⁻³, MoKα radiation, λ = 1.71069 Å, μ(MoKα) = 1.11 cm⁻¹. The structure was solved by direct methods. The parameters were refined by full matrix least squares technique to a final R = 0.088 for 834 reflections with ∥F₀∥ > 4σ(F₀). The dihedral angle between the least-squares plane through the pyrrolidine ring and that through the acetamide group is 90.4°. The N H … O hydrogen bonds connect molecules to form bands parallel to the z axis.     

Synthesis,Crystal Structure and ab Initio Studies of 5-Phenylamino-3-phenylimino-3H[1, 2]dithiole-4-carboxylic acid ethyl ester

Abstract  

5-Phenylamino-3-phenylimino-3H[1, 2]dithiole-4-carboxylic acid ethyl ester, C₁₈H₁₆N₂O₂S₂, (I), has been synthesized and the structure has been solved by X–ray diffraction. The crystals are triclinic, space group P[`1] P\bar{1} , with a = 5.7127(2) ?, b = 12.1757(5) ?, c = 14.0734(5) ?, α = 112.1217(16)°, β = 97.786(2)°, γ = 100.694(2)°, Mr = 356.45, V = 868.11(6) ?³, Z = 2 and R = 0.0373. In the title compound there is an intramolecular N–H···O hydrogen bond. The crystal structure is stabilized only by weak C–H···π and π···π interactions as well as by van der Waals forces. The geometry of the isolated molecule was optimized by ab initio quantum mechanical calculations, employing both molecular orbital Hartree-Fock (HF) and density functional theory (DFT) methods. In the DFT calculation the minimum energy was achieved for a conformation very similar to that of the solid-state molecule.     

Molecular structure of isopropyl 1-phenyl-4-phenylhydrazono-5-oxo-3-pyrazolecarboxylate

The new azopyrazolone dye has been synthesized and its crystal structure has been investigated. Crystals of C₁₉H₁₈N₄O₃ are triclinic: ,a=7.484(1),b=10.646 (1),c=11.897(1) Å, =82.28(1), =72.86(1), =86.83(1)°,Z=2. The structure has been solved by direct methods and refined by full-matrix least-squares techniques toR=0.050 for 2622 unique reflections. The tautomeric form of the molecules has been determined as a hydrazo form. Delocalization of the C5=O3 and C4=N3 -electrons and delocalization of the lone-pair electrons of N1, N3, and N4 atoms has been observed. The intramolecular N–H...O hydrogen bond forms the six-membered ring C₂N₂H...O condensed with the pyrazolone ring. The molecules are connected by intramolecular C–H...O hydrogen bonds.     

Synthesis,spectroscopic characterization and crystal structure of 5-bromo-1-(2-cyano-pyridin-4-yl)-1H-indazole-3-carboxylic acid diethylamide

The title compound 5-bromo-1-(2-cyano-pyridin-4-yl)-1H-indazole-3-carboxylic acid diethylamide, C₁₈H₁₆BrN₅O, is prepared from 5-bromoindazole-3-carboxylic acid methylester. N ¹-arylation is carried out with 4-chloro-2-cyanopyridine and the resulting product is converted to diethylamide by reacting with thionyl chloride and diethylamine. The structure is identified from its FT-IR, ¹H NMR, ¹³C NMR spectroscopy, elemental analysis data and unambiguously confirmed by single crystal X-ray diffraction studies. There are two symmetry independent molecules in the asymmetric unit with no significant differences in bond lengths and angles. The title compound crystallizes in the triclinic system, space group \(P\bar 1\) , with a = 11.2330(2); b = 11.6130(2); c = 15.4710(3) Å, α = 92.515(1)°; β = 109.956(1)°; γ = 107.199(1)°; V = 1788.45(6)ų and z = 4. An intramolecular C-H…N hydrogen bond forms an S(6) ring motif in one of the unique molecules. In the crystal, two molecules are linked about a center of inversion by C-H…O hydrogen bonded dimers generating an R ₂ ² (16) ring motif. The crystal packing is stabilized by C-H…N, C-H…O hydrogen bonds and π…π stacking interactions.     

Molecular structure of 3-(3-oxo-bicyclo[2.2.1]hept-5-en-2-yl)-oxirane-2-carboxylic acid methyl ester

The crystal and molecular structure of an epoxy ester is described. The structure has been solved by vector search methods and refined by least squares methods toR ₁=0.0372 [I>2(I)]. The structure consists of two independent molecules in the asymmetric unit. These molecules are chemically the same. Crystal data: C₁₁H₁₂O₄, triclinic, space group ,a=10.324(3),b=10.553(7),c=10.869(5)Å, =61.77(4), =88.64(4), =88.16(6)°,V=1042.7(9)ų,Z=4.     

Molecular and crystal structure of 4-hexylbenzoic acid: Design of the mesophase

The crystal structure of 4-hexylbenzoic acid C₆H₁₃-C₆H₄-COOH, which forms a nematic mesophase upon melting, is determined. The crystal contains three crystallographically independent molecules. Their molecular skeletons are made up of two almost planar fragments: a benzene ring, π-conjugated with the carboxyl group and a planar zigzag aliphatic fragment. One of the independent molecules forms centrosymmetric dimers via pairs of hydrogen bonds between carboxyl groups, whereas the two others are linked via hydrogen bonds. The dimers in the crystal are packed into pseudostacks with a pronounced nonparallel arrangement of conjugated fragments. There is no good mutual projecting of benzene rings in the stacks, which corresponds to efficient π-stacking interaction. The graph describing the mesophase of this compound contains only one structure-forming element (a hydrogen bond) and corresponds to the nematic mesophase.     

Molecular and crystal structure of mesomorphic para-n-hexyloxybenzoic acid

The triclinic modification of para-n-hexyloxybenzoic acid is studied using X-ray diffraction analysis (MoK _α radiation) at 120 K. The crystallographic parameters of the compound are as follows: space group, $P\overline 1 $ a = 7.8854(4) Å, b = 14.3021(7) Å, c = 33.0513(16) Å, α = 88.738(1)°, β = 85.701(1)°, γ = 78.331(1)°, and Z = 12. The asymmetric unit of the crystal contains six molecules of the acid with different orientations of the aliphatic chain. In the crystal, the molecules are joined into dimers by hydrogen bonds between the carboxyl groups. The crystal packing is built on the principle of the separation of aromatic and aliphatic regions.     

Synthesis and crystal structure of 3-[2-oxo-2-(4-methyloxyphenylsulfonamidophenyl)ethylidene]-3,4-dihydro-1H-quinoxalin-2-one

3-[2-Oxo-2-(4-methyloxyphenylsulfonamidophenyl)ethylidene]-3,4-dihydro-1H-quinox-alin-2-one (4) was synthesized and characterized by ¹H NMR,¹³C NMR, IR, and single-crystal X-ray diffraction techniques. The crystallographic results show that the composition of the title compound is C₂₃H₁₉N₃O₅S. It belongs to triclinic crystal system and P-1 space group, with a=7.273(6) ?, b=9.092(7) ?, c=15.928(13) ?; α=85.135(11)°, β=78.297(10)°, γ=84.619(11)°, V=1024.4(14) ?³, Z=2, D _c=1.457 mg/m³, μ = 0.201 mm⁻¹, F(000)=468, R=0.0597, wR=0.1438. Supplementary material CCDC-281953 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge at www.ccdc.cam.ac.uk/retrieving.html or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44-1223-336033; e-mail: deposit@ccdc.cam.ac.uk.     

Molecular and crystal structure of tris-(2-hydroxyethyl)ammonium 4-chlorophenoxy acetate

Tris-(2-hydroxyethyl)ammonium 4-chlorophenoxy acetate has been synthesized and characterized by ¹H NMR spectra. The molecular structure of this compound has been established by single-crystal X-ray diffractometry (a = 7.5298(23) ?, b = 22.8112(46) ?, c = 10.0921(16) ?, ?? = 111.42(2)°, V = 1613.7(7) ?³, sp. gr. P2₁/c, d _calcd = 1.382 g/cm³). In a cation, the hydrogen atom, in the presence of a nitrogen atom, forms three intramolecular hydrogen bonds with the O atoms of hydroxyl groups [2.29(3)?C2.31(3) ?]. At the same time, all three cation hydroxyl groups are involved in the formation of three intermolecular H bonds with oxygen atoms of the carboxyl anion group [H-O = 1.81(5)?2.06(4) ?].     

The structure of ethyl allyl 1,4-dihydro-2,6-dimethyl-4-[4-(4H-4-oxo-1-benzopyran-2-yl)phenyl]-3,5-pyridine dicarboxylate

The crystal and molecular structure of the title compound has been determined by direct methods, and refined to a finalR of 0.070 for 1466 observed reflections. The compound crystallizes in space group P2_l/n with cell dimensionsa=10.706(8),b=21.127(11),c=12.038(10) Å, Z=4.1,4-dihydropyridine ring adopts a boat shaped conformation. The flavon molecule is planar and it's phenyl ring is almost perpendicular to the 1,4-DHP. The C36 atom of the allyl group shows disorder.     

Molecular co-crystals of carboxylic acids, part 29. The effect of competitive interactions on adduct formation involving 2-aminopyrimidine: the crystal structure of the 1∶1 adduct of 2-aminopyrimidine with indole-2-carboxylic acid

The crystal structure of the 1∶1 adduct of 2-aminopyrimidine with indole-2-carboxylic acid has been determined by single crystal X-ray diffraction, revealing a novel interactive mode. The utility of 2-aminopyrimidine in formation of stable hydrogen-bonded networks with carboxylic acids is discussed and the modes of interaction are reviewed.     

Molecular co-crystals of carboxylic acids, part 29. The effect of competitive interactions on adduct formation involving 2-aminopyrimidine: the crystal structure of the 1∶1 adduct of 2-aminopyrimidine with indole-2-carboxylic acid

The crystal structure of the 1∶1 adduct of 2-aminopyrimidine with indole-2-carboxylic acid has been determined by single crystal X-ray diffraction, revealing a novel interactive mode. The utility of 2-aminopyrimidine in formation of stable hydrogen-bonded networks with carboxylic acids is discussed and the modes of interaction are reviewed. Part 28.,Aust. J. Chem., 1997, (submitted).     

Crystal and molecular structure of benzoyl-l-leucyl-glycine ethyl ester (l-LEUGLY)

The crystal structure of the dipeptide derivative benzoyl-l-leucylglycine ethyl ester has been determined by direct methods (Multan 78), and refined by fullmatrix least squares toR=0.092 for 1638 reflections;I>3(I), CuK radiation. The space group isP2₁2₁2₁,a=20.679(7),b=16.440(6),c=11.034(5) Å,Z=8. Disorder observed in the ethyl ester and leucyl side-chains of the two independent molecules per asymmetric unit probably accounts, at least partially, for the weak diffracting power of the crystals. Both molecules exhibit markedly coiled hydrogen-bonded conformations. An attempt was made to obtain improved hydrogen bond geometry by the use of neutron diffraction data.     

Molecular and crystal structures of 1-methyl-2-Oxo-3-acetoxy-4-hydroxy-4-(Phenyl)piperidine, 1-ethyl-2-oxo-3,4-dihydroxy-4-(Pyridyl)piperidine, and 1-benzyl-2-oxo-3,4-dihydroxy-4-(Pyridyl)piperidine and the role of hydrogen bonds in molecular packing in crystals

The molecular and crystal structures of 1-methyl-2-oxo-3-acetoxy-4-hydroxy-4-(phenyl)hydropyridine, 1-ethyl-2-oxo-3,4-dihydroxy-4-(pyridyl)piperidine, and 1-benzyl-2-oxo-3,4-dihydroxy-4-(pyridyl)piperidine are determined by X-ray diffraction analysis. These three hydroxy derivatives of hydropyridine are the convenient model compounds in studies of the influence of intramolecular and intermolecular hydrogen bonds on the conformation and packing of molecules in crystals. The molecules of hydroxy derivatives possess a considerable conformational flexibility and can form an extended network of intramolecular and intermolecular hydrogen bonds. It is shown that these compounds more often than others form noncentrosymmetric and polysystem crystals. The role of the molecular association and the type of hydrogen-bonded associates (syntons) in crystal packing are discussed.     

Molecular and crystal structure of 2-amino-4-(tricyclo[3.3.1.1.3,7]decyl-1)-6-N-methyl-piperazino-1,3,5-triazine

The crystal and molecular structure of the title compound has been determined by X-ray diffraction. The compound crystallizes in the rhombohedral space groupR3 witha=b=c=17.804(9)Å,===116.48(2)° andZ=6. The structure was solved by direct methods and a full-matrix least-squares refinement converged to a finalR=0.061 for 1922 unique reflections. The adamantyl moiety is statically disordered in the crystal structure, and adopts two conformations related by the rotation of approximately 60° about the C(4)-C(9) bond. A hydrogen bond between N(7)N(21) arranges molecules into hexamers stacked along the threefold axis and provides for empty hydrophobic channels bounded by the adamantyl groups.     

The crystal structure of 5-amino-2-nitrobenzoic acid

The crystal structure of 5-amino-2-nitrobenzoic acid (5A2NB) was determined by the X-ray diffraction method. The 5-amino-2-nitrobenzoic acid crystallizes in the monoclinic P2₁/c space group with a = 3.898(2) Å, b = 13.531(3) Å, c = 14.301(3) Å, and = 90.83(3)°. The adjacent molecules form a cyclic dimmer by intermolecular hydrogen bonds of type O—HsO with their carboxyl groups. In the crystal structure NH₂ group forms a three-center hydrogen bond with oxygen atoms of NO₂ group. The IR spectrum and thermal properties of acid are discussed.     

Mesophase design: II. Molecular structure and crystal packing of 4-alkyloxycyanobiphenyls

A joint analysis of the molecular geometry and crystal packings of the members of a homologous series of 4-alkyloxycyanobiphenyl C _n H_{2n + 1}-O-C₆H₄-C₆H₄-CN with n = 5–12 does not reveal a direct relationship between the molecular geometry and mesogenic properties of these compounds. The crystal packings of all of them are built from alternating loose aliphatic and dense aromatic regions. The closely packed aromatic regions of crystals exhibit weak intermolecular directed interactions of different natures which are responsible for the occurrence of the mesophase. The type of mesophase depends on the number s of structure-forming elements, the ratio of their energies (if s > 1), and the melting temperature of the compound. A graph system is used to describe the crystal packings and the mesophase. It is shown that, although the mesophase graph is similar to the crystal graph, they may differ somewhat, because some symmetric limitations (for example, lattice) on the molecular associate structure are removed in the melt.