Structure of 1-ethyl-2-(2′-chloro-4′-nitrostyryl)benzimidazole

The title compound C₁₇H₁₄ClN₃O₂ (et-4-nsbiz) is monoclinic, witha=12.240(2),b=12.144(4),c=10.544(4)Å,=100.09(2)°,V=1543(1)ų,Z=4,D _x =1.411 g cm^–3, (MoK)=0.71073Å,=2.57 cm^–1,F(000)=680,M _r =327.77,T=298K. The structure was solved by heavy atom and Fourier methods and refined toR=0.049 for 1503 unique observed reflections in space groupP2₁/c. Except for the ethyl group, the molecule is almost planar, with a dihedral angle of 9.5(5)° between the benzimidazole and phenyl rings. The dihedral angle between the ethyl group and the benzimidazole ring to which it is attached is 91.5(2)°.     

Crystal Structure of 3′-(4-Methoxyphenyl)-2-Phenyl-4′-(4-Ethoxyphenyl)-1,2-Dihydro-4H,4′H-Spiro [Isoquinoline-3,5′-Isoxazol]-4-One

The title compound, 3′-(4-methoxyphenyl)-2-phenyl-4′-(4-ethoxyphenyl)-1,2-dihydro-4H,4′H-spiro[isoquinoline-3,5′-isoxazol]-4-one was synthesized from the reaction of dipolarophile with p-methoxybenzadoxime in the presence of sodium hypochlorite in chloroform solution. The structure of the synthesized compound was determined by IR, ¹H NMR, mass spectroscopic data, ¹³C NMR spectroscopy, elemental analysis and X-ray crystallography. The structure was solved in monoclinic, space group C2/c with a = 21.941 (4), b = 17.233 (3), c = 15.404 (3) Å, β = 122.193 (2), V = 4928.9 (16) Å³, Z = 8 and with R_int = 0.154. The geometry of the title compound showed that the piperidine ring adopts a half-chair conformation. In the crystal structure, molecules are linked by C–H···O and C–H···N contacts. Weak C–H···π interactions plays an important role in stabilizing the supramolecular structure.     

Synthesis and crystal structure of 1-(1′,3′-dimethyl-5′-chloropyrazol-4′-carbonyl′-3-(2′-chlorophenyl)-5-amino-4-cyanopyrazole

The title compound 1-(1,3-dimethyl-5-chloropyrazol-4-carbonyl)-3-(2-chlorophenyl)-5-amino-4-cyanopyrazole (C₁₆H₁₂Cl₂N₆O) has been synthesized and characterized by X-ray diffraction: Triclinic, space group P1, with a = 8.6712(8) Å, b = 9.5091(10) Å, c = 11.2170(11) Å = 71.531(2)°, = 84.683(2)°, = 74.099(2)° Z = 2; V = 843.7(14) ų. C(10), O(1), C(11), and N(2) atoms are coplanar with the average deviation of 0.0071 Å, which form 11.03° and 43.93° dihedral angles with pyrazole planes (I) and (II), respectively.     

Structure of 2-(2′-bromo-5′-nitrostyryl)benzothiazole

The title compound C₁₅H₉BrN₂O₂S (brnsb) is monoclinic, witha=7.730(2),b=26.847(5),c=7.773(2) Å,=117.48(1)°,V=1431(1) ų,Z=4,D _x=1.677,(MoK)=29.9 cm^–1,F(000)=720,T=298K in space groupP2₁/c. The structure was solved by heavy atom and Fourier methods and refined toR=0.034 for 1776 unique observed reflections. The molecule is nearly planar, with a dihedral angle of only 3.8(1.1)° between the benzothiazole and phenyl rings. The C-S-C angle in the thiazole ring is 89.0°, while the C-N-C angle in that ring is 111.5(3)°.     

Physical Studies of Homologous 4-Cyanophenyl Esters of 4′- n-Alkylcinnamic Acids

The mean polarizabilities of homologous series of nematic liquid crystals of 4-cyanophenyl esters of 4′- n-alkylcinnamic acids are evaluated by using the MLδP method. From these polarizabilities the mean diamagnetic susceptibilities of the liquid crystals are also calculated. The orientational order parameters of these compounds are also estimated using the Vuks and Neugebauer methods. The variation of the order parameter with temperature is discussed.     

Some Cholesteric Derivatives of S-(+)-4-(2′-Methylbutyl) Phenol

A facile synthesis of S-(+)-4-(2′-methylbutyl)phenol and its interaction with a number of different acids are used to provide a wide variety of new chiral nematic liquid crystals. These new cholesterogens display a range of liquid crystal and other physical properties, and are potentially useful for application in display device and other technologies. Of particular interest in this respect are the materials containing two chiral centres and which therefore have very small helical pitch lengths-as low as 0.1 μm.     

Synthesis and Structure of 1-Chlorosulfonyl-2-(4′-Nitrophenoxy)-5-Methylbenzene

Abstract  Diphenyl ethers are structural elements found in medicinally useful antibiotics such as vancomycin as well as in biological toxins in the environment such as dioxins. The purpose of this paper is to report the synthesis and characterization of the previously unreported 1-chlorosulfonyl-2-(4′-nitrophenoxy)-5-methylbenzene, a trisubstituted diphenyl ether derivative. ¹H NMR (CDCl₃) δ 2.45 (3H, methyl₅, s), 7.07 (1H, H₄, d, J ~8.27 Hz), 7.13 (2H, H_2′, H_6′, d, J ~9.0 Hz), 7.54 (1H, H₃, d, J ~8.28 Hz), 7.87 (1H, H₆, s), 8.22 (2H, H_3′, H_5′, J ~9 Hz); ¹³C NMR (CDCl₃) δ 20.7, 118.2, 121.9, 126.0, 129.8, 135.2, 135.8, 137.8, 143.8, 150.3, 161.4. An X-ray analysis has provided valuable insight into the effect of steric factors on the three dimensional shape of this compound which serves as a useful advanced intermediate in the synthesis of these biologically active molecules. A multistep synthesis of this molecule has been designed by retrosynthetic analysis as part of an ongoing program aimed at a function-oriented, multi-step economical synthesis of vancomycin lead antibiotics. Crystals are triclinic, space group P-1, a = 7.6537(15), b = 8.976(2), c = 11.050(2) ?, α = 67.645(11), β = 79.735(11), γ = 87.798(10)°, V = 690.5(2) ?³, Z = 2. Graphical Abstract  The synthesis and characterization of the previously unreported trisubstituted diphenyl ether derivative are reported. The phenyl rings form a dihedral angle of 64.49(4)° and the chlorosulfonyl group has a C–C–S–Cl torsion angle of 62.95(11)°.      

Crystal and molecular structure of 2′,4′-dimethoxyflavone

C₁₇H₁₄O₄,M _r =282.3, triclinic,P-1,a=8.469(3),b=8.516(2),c=20.425(8)Å,=84.95(3),=81.98(3), =70.47(2)°,V=1373(13)ų,Z=4,D _x =1.365 g cm^–3, (MoK )=0.71069 Å,=0.91 cm^–1,F(000)=592,T=294K,R=0.038 for 3577 observed reflections (F>3 (F)). The asymmetric unit is composed of two molecules. These two molecules, which are in planar conformations, differ in 4-methoxyl group orientation. Short intramolecular contacts are found between the -benzopyran portion and the dimethoxyphenyl ring.     

A structural model for a new class of conformationally constrained retinoid: (2Z,4E)-4-[3′,4′-dihydro-1′(2′H)-naphthalene-1′-ylidene]-2-butenoic acid

Racemic (2Z,4E)-4-[3′,4′-dihydro-1′(2′H)-naphthalene-1′-ylidene]-2-butenoic acid (1) is a polyene chain-shortened analog of (9Z)-retinoic acid (3) which uses a tetrahydronaphthyl ring to conformationally constrain the C6-C7 single bond (retinoic acid numbering). The structure of (1) was obtained to determine the effects of the tetrahydronaphthyl ring on the ring to polyene chain conformation as compared to a published crystal structure for (9Z)-retinal (2). The results reveal significant differences between the solid state structures of (1) and (2), particularly for torsion angles about C6, C7 and C8, C9. The title compound crystallizes in the centrosymmetric monoclinic space groupP2₁/n withZ=4. (Cell dimensions:a=10.863(2) Å,b=7.637(2) Å,c=15.781(3) and β=106.11(3)°.) The structure was refined toR=3.88% for those 1132 unique data with |F _o|>6σ(F _o). In the crystal structure, the molecules adopt a hydrogen bonded dimeric structure.     

Polymorphism and design of noncentrosymmetric crystals of 4-hydroxybenzaldehyde-4-nitrophenylhydrazone and N′-(2-phenyl-1H-indole-3-aldehyde)-4-nitrophenylhydrazone

The products of crystallization of 4-hydroxybenzaldehyde-4-nitrophenylhydrazone (I) and N′-(2-phenyl-1H-indole-3-aldehyde)-4-nitrophenylhydrazone (II) from different solvents are studied by X-ray diffraction with the aim of examining the polymorphism of hydrazone derivatives. The structural features of the crystals prepared are analyzed. It is shown that, in the case when molecules of organic compounds with a high molecular hyperpolarizability are capable of forming stable acentric supramolecular associates in the crystal, knowledge of their polymorphism offers strong possibilities for designing the noncentrosymmetric crystal structure necessary for a manifestation of the nonlinear optical activity.     

Crystal and molecular structure of 2-(2′-chloro-5′-nitrostyryl)benzoselenazole

The title compound C₁₅H₉ClN₂O₂Se (nsbse) is orthorhombic, witha=6.823(2),b=7.860(2),c=26.349(5) Å,Z=4,D _x =1.709,(MoK)=28.3 cm^–1,F(000)=720,T=298K in space groupP2₁2₁2₁. The structure was solved by heavy atom and Fourier methods and refined toR=0.045 for 1095 unique observed reflections. The molecule is almost planar, with a dihedral angle of 4.8(2)° between the benzoselenazole and phenyl rings. The C-Se-C angle in the selenazole ring is very small, 84.6(4)°, while the C-N-C angle in that ring is 113.7(7)°.     

Structural studies of N-2-(3-picolyl)- and N-2-(4-picolyl)-N′-tolylthioureas

Reactions of 2-aminopicolines with 2- and 4-tolyl isothiocyanates yielded N-2-(4-picolyl)-N-4-tolylthiourea, 1, N-2-(3-picolyl)-N-4-tolylthiourea, 2, and N-2-(4-picolyl)-N-2-tolylthiourea, 3. Compound 1 is monoclinic, of space group P2₁/c with a = 7.456(1) Å, b = 13.135(3) Å, c = 13.959(3) Å, = 104.99(3)°, and V = 1320.5(5) ų with Z = 4, for d _calc = 1.294 g/cm³. Compound 2 is triclinic, of space group with a = 6.877(3) Å, b = 7.590(5) Å, c = 13.213(9) Å, = 78.38(2)°, = 77.96(4)°, = 86.36(4)°, and V = 660.5(7) ų with Z = 2, for d _calc = 1.294 g/cm³. Compound 3 is monoclinic, of space group P2₁/c with a = 12.604(2) Å, b = 15.592(3) Å, c = 6.875(2) Å, = 91.05(2)°, and V = 1350.9(2) ų with Z = 4, for d _calc = 1.265 g/cm³. The three thioureas are found in both solid state and solution in a conformation resulting from intramolecular hydrogen bonding. Compounds 1 and 3 present an intermolecular hydrogen bond involving the thione sulfur and the NH hydrogen, which is not present in 2 owing to the steric hindrance of the methyl group in the phenyl ring. The geometry of the molecule is affected by the position of the methyl groups on the pyridine and aryl rings.     

X-ray crystal structure of 2-hydroxy-2′-(1,4-bisoxo-6-hexanol)-1,1′-biphenyl

The X-ray crystal structure of 2-hydroxy-2-(1,4-bisoxo-6-hexanol)-1,1-biphenyl, 3, is presented. This molecule crystallizes in the monoclinic space group P2₁/n (a = 9.440(2), b = 12.679(3), c = 11.679(3) Å = 94.60(2)° V = 1382.5(5) ų; Z = 4). One of the unique features of the X-ray structure of 3 is the intramolecular hydrogen bonding. The hydrogens of the phenolic and hydroxy groups occupies bridging positions via hydrogen bonding to an ether oxygen (O₁) and a phenolic oxygen (O₄), respectively. This hydrogen bonding does not affect the interplanar angle between phenyl rings (49.34°), which is in the range expected for ortho-disubstituted biphenyl compounds. The hydrogen bonding of this type explains why it is difficult to alkylate both phenoxy groups of 2,2-biphenol with tetrahydropyranyl protected 2-(2-chloroethoxy)ethanol.     

Structure of 2,2′-anhydro-3′-O-acetyl-2′thio-1-β-D-arabinofuranosylcytosine hydrochloride1

2,2-Anhydro-3-O-acetyl-2-thio-1--D-arabinofuranosylcytosine hydrochloride crystallizes in space group P2₁2₁2₁ witha=10.373(1),b=14.517(2),c=9.496(1) Å. Reflections were measured on a diffractometer and the structure was solved by direct methods. Least-squares refinement converged atR=0.056 andR _w =0.063. The study of this crystal structure showed that the alterations in the geometry of 2,2-anhydro-1--D-arabinofuranosylcytosine when the bridge oxygen is replaced by sulfur are localized in the region of the fused ring. The angle at the bridge atom decreases to nearly 90°, with concomitant enlargements of about 5°–7° in the angles opposite to the bridge atom. Angle C(1)-N(1)-C(6) decreases by 4°. Also, the amount of double bond character in the bond formed by C(2) and the bridge atom decreases. A survey of the conformational features of S,2-cyclonucleosides and comparison with O,2-cyclonucleosidcs showed that their preferred conformations are the same. However, S,2-cyclonucleosides exhibit a wider range of P and values. This correlates with a greater ease of the sulfur containing five-membered ring to pucker as compared to the oxygen-cyclo ring.This paper is part of the authors' dissertation (Vitali, 1986).     

Structure of a liquid crystal of 4-cyano-4′-n-octyloxybiphenyl

The structure of a liquid crystal of 4-cyano-4′-n-octyloxybiphenyl (C₂₁H₂₅NO) is determined by X-ray diffraction analysis. The compound crystallizes in the triclinic crystal system with unit cell parameters a = 7.322(1) Å, b = 12.693(3) Å, c = 20.393(2) Å, α = 92.45(1)°, β = 99.96(1)°, γ = 99.35(2)°, and space group $P\bar 1$ . The structure is solved by the direct method and refined to R = 0.057. Two independent molecules are located in the asymmetric unit. No short intermolecular contacts are observed in the crystal packing.     

Crystal structure of 5-(2′-aminophenyl)-2-dimethylamino-1,3,4-thiadiazole

The crystal structure of 5-(2′-Aminophenyl)-2-dimethylamino-1,3,4-thiazole is determined by X-ray diffraction. The compound is prepared by an unusual recyclization of 3-N, N-dimethylthioureidoquinazolin-4(3H)-one. The crystal is monoclinic, space group P2₁/c, a = 7.420(2) Å, b = 10.466(5) Å, c = 14.752(9) Å, β = 109.2(4)°, ρ_calcd = 1.359 g/cm³, and Z = 4 for the C₁₀H₁₂N₄S composition. The molecule consists of the thiadiazole and phenyl rings and the dimethylamine N(CH₃)₂ and amine NH₂ groups attached to the rings. The molecule as a whole is planar. The dihedral angle between the rings is 8.9°. The N(1) and N(4) atoms in the molecule are bound through the intramolecular interaction (2.76 Å). Molecules, which are linked in pairs by antiparallel hydrogen bonds, form a framework structure.     

Crystal structures of two substituted biphenyl derivatives: 5,5′-di t-butyl-2-2′-biphenyldiol and 5,5′-dimethyl-2,2′-biphenyldiol

5,5-Di t-butyl-2,2-biphenyldiol (I), C₂₀H₂₆O₂, crystallizes in the orthorhombic space group P2₁2₁2₁ with a = 18.243(2), b = 9.947(2), c = 9.685(3) Å, and Z = 4; 5,5-dimethyl-2,2-biphenyldiol (II), C₁₄H₁₄O₂, crystallizes in the monoclinic space group P2₁/c with a = 9.959(2), b = 7.932(3), c = 15.392(2) Å, = 105.43(2)°, and Z = 4. The aromatic rings are tilted by 52.7(1) and 43.8(1)° to each other in compounds (I) and (II), respectively. Strong intra- and inter-molecular H-bonds connect the molecules in the crystals.     

Surface Order Parameter of 4-n-Heptyl-4′-Cyanobiphenyl

We measured the order parameter near the interface between a liquid crystal and the solid substrate treated by several methods. The interfacial order parameter is different according to the surface treatment, and is larger than the bulk order parameter. Moreover, in the temperature above the clearing point, the interfacial order still has a finite value.     

Synthesis of 1 - (4-Alkoxy or Alkyl- Benzoyloxy-Phenyl) - 2- (4′- Pentylphenyl) - Ethanes. Influence of the Central Group on the Mesomorphic Properties

An homologous series of mesomorphic compounds, the I-(4-alkoxy or alkyl-benzoyloxyphényl)-2-(4′-pentylphenyl)-ethanes, has been synthesized. The compounds with R = alkyl have low-melting points and wide mesomorphic ranges, for example from 33.5°C to 106.5C. The compounds with R = alkoxy exhibit a smectic polymorphism; for example a compound of this series is successively smectic B, F and C. The influence of the central linkage when the ethane group is replaced by an ester, single bond, ethylene, azomethine, azo, methylenecetone or cetone groups, is discussed.     

X-ray structure investigation of two polymorphic modifications of 1-acetyl-3-(4-nitrophenyl)-5-(2′-furyl)pyrazoline

Two polymorphic modifications of 1-acetyl-3-(4-nitrophenyl)-5-(2′-furyl)pyrazoline (I) are investigated by X-ray diffraction with the purpose of analyzing the factors responsible for the formation of crystal structures of the optical nonlinear organic compounds. Both modifications crystallize simultaneously upon slow evaporation of a solution of compound I in an isopropanol-acetonitrile (3: 1) mixture. It is found that the molecular geometry of the polymorphic modifications is characterized by the rotation of the furan substituent with respect to the plane of the pyrazoline ring. The molecular hyperpolarizabilities (β) of both conformers are calculated.