The Mesogenic Behavior of Isomeric and Nonisomeric Series of Novel Azoesters. 4-(4′-n-Alkoxy Benzoyloxy) Phenylazo-2″-Bromobenzenes

A novel homologous series: 4-(4′-n-alkoxy benzoyloxy) phenylazo-2^″-bromobenzenes is synthesized and studied with a view to understanding and establishing the effects of molecular structure on mesogenic behavior in a series. The mesogenic property commences from fifth homologue to the last homologue. The transition temperatures of the series are relatively low ranging between 68°C and 143°C. The mesogenic range varies between 6°C and 22°C. The novel azoester series is nematogenic without exhibition of any smectogenic property and an average thermal stability of 89.4°C. The mesogenic behavior of the novel series is compared with structurally similar isomeric/nonisomeric other known series.     

Relation Between Structure and Mesogenic Activity in α,α′-Dimethylbenzalazines Influence of Intramolecular H-Bonding (II)

The central molecular geometry of three series of benzalazines: 4,4′-Dialkoxy-α,α′-Dimethylbenzalazines, 4,4′-dialkoxy-2,2′-dihydroxy-α,α′-Dimethylbenzalazines, and 4,4′-dialkoxy-2-hydroxy-α,α′-Dimethylbenzalazines was studied by U.V., I.R., and ¹H.N.M.R. spectroscopy.

All the compounds studied show the E-E configuration. The intramolecular H-bond between the nitrogen of the azine central group and the H of the OH group in position 2 of the aromatic ring is “exceptionally” strong in accordance with the calculations made using Schaefer's equation. This bond conditions the geometry of the molecules, as well as their mesogenic properties. The intramolecular H-bonding favors the formation of mesophases whose properties are also related to the number of bonds of this type which the molecules contain.     

A Homologous Series containing Ester and Amide Groups as Central Linkages: 4(4'-n-Alkoxybenzoyloxy)-4”-n-Heptyloxy Benzanilides

The first extensive homologous series, comprising thirteen members, with both ester and amide groups as central linkages has been synthesised and the mesomorphic properties have been determined. The homologues are comparatively high melting and exhibit liquid crystal phases. The molecular structure seems to favour smectic properties since smectic phases commence with the ethoxy derivative as a monotropic phase. The ethoxy to hexadecyloxy derivatives are poly-mesomorphic in nature, while the octadecyloxy derivative is purely smectic. The mesomorphic behaviour and mesophase thermal stabilities are compared with those of other structurally related series, and the effect of the amide group on mesomorphism is evaluated.     

Synthesis and Mesomorphic Properties of the Homologous Series of Di-(4′- n-alkylphenyl)- trans-cyclohexane-1,4-dicarboxylates

The homologous series of di-(4′- n-alkylphenyl)- trans-cyclohexane-1,4-dicarboxylates in which the alkyl group is C₁-C₁₂ has been prepared by esterification of trans-1,4-cyclo-hexanedicarboxylic acid or dicarbonyl chloride with 4-alkylphenols. Mesomorphic properties and phase transitions as determined by hot-stage polarizing microscopy and DSC are discussed in relationship to various structural features. Comparisons of these properties with those for the corresponding alkoxy series and the analogous terephthalic acid diesters are also presented and discussed.     

Electronic Properties,Reactivity, Flexibility,Polarity, Thermodynamic Properties,and Dynamic Simulation of a Series of Hybrid Organic–Inorganic Polyoxoselenomolybdate Compounds

Crystallography Reports - A large theoretical study of three hybrid inorganic-organic polyoxoselenomolybdate-based systems (C7H10N)4[Se2Mo5O21]⋅5H2O (1), (C6H8N)4[Se2Mo5O21]⋅7H2O (2)...     

Syntheses and Crystal Structures of a Series of Dysprosium–Manganese–Sodium 12-Metallacrown-4 Compounds with Halogenated Benzoate Bridging Anions

Journal of Chemical Crystallography - A series of heterotrimetallic dysprosium–manganese–sodium 12-metallacrown-4 compounds has been synthesized and characterized by single-crystal...     

Syntheses,Structures and Optical Properties of a Series of Lanthanide Complexes with Chelidamic Acid and 4,4′-Bipyridyl

Abstract  

The title complexes, (C₁₀H₈N₂)·[Y(C₇H₃NO₅)(C₇H₄NO₅)·2H₂O]·3H₂O (1), (C₁₀H₈N₂)·[Er(C₇H₃NO₅)(C₇H₄NO₅)·2H₂O]·3H₂O (2), (C₁₀H₈N₂)·[La(C₇H₃NO₅)(C₇H₄NO₅)·2H₂O]·4.5H₂O (3), (C₁₀H₈N₂)·[Sm(C₇H₃NO₅)(C₇H₄NO₅)·2H₂O]·4.75H₂O (4), (C₁₀H₈N₂)·[Pr(C₇H₃NO₅)(C₇H₄NO₅)·2H₂O]·4.75H₂O (5) were synthesized and characterized by X-ray single-crystal diffraction. The crystal structures of 1–2 reveal that they are isomorphous, among which the metal atoms are all eight-coordinate with a distorted dodecahedron coordination geometry. The structures of 3–5 are isomorphic, among which the metal atoms are all nine-coordinate with distorted tricapped trigonal prismatic coordination geometries by two chelidamic acid ligands. Complexes 1–5 are formed into 3D networks by H-bonds. The optical properties of 1–5 were investigated in terms of fluorescent spectra, which all exhibit strong luminescence.     

Synthesis and Evaluation of Liquid Crystal Behavior of a Novel Homologous Series: 4-(4′-n-Alkoxy benzoyloxy) Phenylazo-2″, 6″-dimethylbenzenes

A novel homologous series entitled 4-(4′-n-alkoxy benzoyloxy) phenyl azo 2^″, 6^″-dimethyl benzenes consisting of 12 members is reported. Liquid crystal behavior as a nematogenic mesophase commences from the pentyloxy homologue monotropically and then continues enantiotropically until the last hexadecyloxy homologue without exhibition of any smectogenic behavior. An odd-even effect is observed for nematic-isotropic transition curve of the phase diagram. The textures of the nematic mesophase are of the threaded or Schlieren type. Analytical and spectral data support the molecular structure of the homologues. Transition temperatures of the novel homologues were determined by an optical polarizing microscopy. Liquid crystal properties of a novel homologous series are compared with other known homologous series. The average thermal stability for the nematic phase is 77.1°C.     

Spectroscopic, Thermal and Structural Studies of Cocrystals of 2,2′-Diamino-4,4′-bis(1,3-thiazole) with 2,5-Bis(4-pyridyl)-3,4-Diaza-2,4-Hexadiene and 1,2-Bis(4-pyridyl)Ethylenediamine

Abstract  

Two cocrystals of 2,2′-diamino-4,4′-bis(1,3-thiazole) (DABTZ) with 2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene (bpdh) and 1,2-bis(4-pyridyl)ethylenediamine (bpen) {[(DABTZ)(bpdh)] and [(DABTZ)(bpen)], respectively} have been synthesized and characterized by elemental analysis, IR-, ¹H NMR-, ¹³C NMR spectroscopy and were studied by thermal analysis and X-ray crystallography. Self-assembly of these compounds in the solid state is likely caused by hydrogen bonding with minor contributions from π–π stacking, C–H···π and possibly charge transfer interactions.     

Chain Ordering and Sm-N Transition in Different Members of the Homologous Series 4-(4′- n-AIkoxy Benzylideneamino) Biphenyls

Our extension of Marcelja's theory of nematic-isotropic transition to the smectic A phase is used to calculate the smectic A-nematic (Sm-N) transition temperatures for the homologous series 4–(4′- n-alkoxy benzylideneamino) biphenyls. In a mean field calculation, explicit inclusion of the conformational energies of the alkyl chain of a molecule in the partition function shows an even-odd effect generally observed in experiments on Sm-N transitions. It is found that the members of this series showing the smectic phase will have first order Sm-N transitions and the transition entropies for individual members are calculated.     

Polymorphism in Dethoxyprone,a steroidal anesthetic. II. Crystal and molecular structure of 11α-dimethylamino-2β-ethoxy-3α-hydroxy-5α-pregnan-20-one (Dethoxyprone,form II)

The crystal and molecular structure of 11-dimethylamino-2-ethoxy-3-hydroxy-5-pregnan-20-one (Dethoxyprone, formII) (C₂₅H₄₃NO₃) has been determined by direct methods, and refined to a finalR of 0.067 for 4508 observed reflections. The compound crystallizes in space groupP2₁2₁2₁ with cell dimensionsa=10.830 (2),b=12.703 (2),c=17.490 (1) Å;Z=4,D _x =1.12 g cm^–3, (CuK )=5.28 cm^–1. The rings of the steroid skeleton are trans connected. Rings A, B, and C have chair conformations, while ring D has a half-chair conformation. The molecules are hydrogen bonded in a head to tail fashion through the hydroxy and keto groups.     

Syntheses and Crystal Structures of Two New Cadmium(II) and Nickel(II) Complexes with 1,4-Phenylenediacetate and 2,2′-Bipyridyl-Like Ligands

Abstract  

Two new complexes, namely [Cd(PDA)_0.5(2,2′-bpy)Cl](H₂PDA) (1) and [Ni(PDA)(phen)(H₂O)]₂ (2) (H₂PDA = 1,4-phenylenediacetic acid, 2,2′-bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline), have been synthesized and characterized by elemental analysis, IR spectra and X-ray crystal diffraction. Single-crystal X-ray diffraction analysis shows that complex 1 crystallizes in the triclinic space group P-1 with unit cell dimensions a = 8.760 (4) ?, b = 11.190 (5) ?, c = 13.917 (7) ?, α = 110.383 (5)°, β = 101.736 (5)°, γ = 100.612 (5)°, V = 1202.8 (10) ?³, Z = 2, R ₁ = 0.0314 and wR ₂ = 0.0898. Complex 2 crystallizes in the monoclinic space group P2(1)/n with unit cell dimensions a = 9.911 (3) ?, b = 17.924 (6) ?, c = 10.638 (4) ?, β = 94.998 (5)°, V = 1882.7 (11) ?³, Z = 2, R ₁ = 0.0397 and wR ₂ = 0.1150. In complex 1, Cd(II) ions are alternately bridged by PDA ligands and chloride ions into 1D chains and the PDA ligands display trans-configuration. Complex 2 is a dimer and two Ni(II) ions are linked by two PDA ligands with cis-configuration, resulting in a cyclic structure. In spite of these differences, both in complexes 1 and 2 there are π–π stacking interactions and hydrogen bonding to make them 3D supramolecular frameworks.     

Properties of the Liquid Crystals Formed by the N-Oxides of Certain 4-(4′-pyridyl)phenyl 4″-n-Alkoxybenzoates: Comparison of the N-Oxide and Cyano-groups as Mesogenic Terminal Substituents

The liquid liquid crystal transition temperatures of the N-oxides of certain 4-(4′-pytidyl)phenyl 4″ -n-alkoxybenzoates are reported. The effects on smectic and nematice thermal stability of the N-oxide function and the cyano-group in terminal positions in mesogens are compared and discussed.     

Spectroscopic and Thermal Study of Mixed Ligand Complexes of Cobalt (II) with β-Diketones and Pyrazinamide.

Abstract

The synthesis of mixed ligand of cobalt (II) with β-diketones (β-dik) (acetylacetone and hexafluoroacetylacetone) and pyrazinamide is proposed. The compounds were investigated by IR- and diffuse reflectance spectroscopies, differential thermal analysis. It is shown that Co (II) β-diketonates (acetylacetone, hexafluoroacetylacetone) mixed ligand complexes with pyrazinamide have a structure corresponding to a distorted octahedron, having D_4h symmetry. The complexes are bonded through hydrogen bonds via water molecules.     

Two Mononuclear Compounds with bis(Pyrimidin-2-yl)amine as a Ligand and as a Hydrogen-bonded Lattice Molecule. Synthesis, Structure and Spectroscopy of {[M(dipm)(H2O)(A)](dipm)(A)(H2O)} (M?=?Cd with A?=?ClO4; and Zn with A?=?BF4)

Abstract  Two isostructural mononuclear compounds with formula {[Cd(dipm)(H₂O)(ClO₄)](dipm)(ClO₄)(H₂O)} (1) {[Zn(dipm)(H₂O)(BF₄)](dipm)(BF₄)(H₂O)} (2) and (in which dipm = bis(pyrimidin-2-yl)amine) have been synthesised and characterised by X-ray crystallography and infrared spectroscopy. The structure of compound 1 has been solved in the space group P2₁/n with a = 18.860(4), b = 8.579(2), c = 20.917(4) ?, β = 101.33(3)°, V = 3318.4(12) ?³, Z = 4 with final R = 0.0454. The structure of compound 2 has also been solved in the space group P2₁/n with a = 19.026(4), b = 8.389(1), c = 20.720(4) ?, β = 101.37(3)°, V = 3242.2(10) ?³, Z = 4 with final R = 0.0689. The geometry around the metal ions is octahedral, and is constituted by four nitrogen atoms from two dipm molecules, an oxygen atom from a water molecule and a semi-coordinating anion atom ( for compound 1 and for compound 2). In the lattice are also present: a non-coordinating water molecule, an anion molecule and a dipm molecule. For compound 1, the Cd–N distances are between 2.296 and 2.328 ?. The distance is 2.310 ? and the is 2.477 ?. The Zn–N distances in compound 2 are between 2.121 and 2.164 ?. The distance is 2.147 ? and the distance is 2.373 ?. A hydrogen bond interaction of the Watson–Crick type is observed between the amine N atom of a dipm ligand to a pyrimidyl N atom and a non-coordinating dipm ligand with N···N distances, which vary from 3.066(5) to 3.109(5) ?. Furthermore medium to strong hydrogen bond interactions are present between oxygen atoms of the water molecules and the anions of the compounds. Index Abstract  Two isostructural mononuclear compounds with formula {[Cd(dipm)(H₂O)(ClO₄)](dipm)(ClO₄)(H₂O)} (1) {[Zn(dipm)(H₂O)(BF₄)](dipm)(BF₄)(H₂O)} (2) and (in which dipm = bis(pyrimidin-2-yl)amine) have been synthesised and characterised by X-ray crystallography and infrared spectroscopy. . Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Synthesis and Structural Characterization of Bis(μ2-Iodo)-Bis(Diethyl Ether)-(N-N′-(Bis(2,6-Diisopropylphenyl)Pentane-2,4-Diketiminato)-Lithium-Chromium, a Cr(II) (β-Diketiminato) Complex with a Coordinated LiI Salt

Abstract  Addition of CrI₂ to the lithium salt of N-N′-bis(2,6-diisopropylphenyl)-2,4-diketiminate in diethylether yields a Cr(II) iodide complex with a coordinated, solvated LiI salt. This complex is the intermediate in the synthesis of a bridging iodide complex that is itself a precursor to a side-on bridging dinitrogen complex. This complex crystallizes in the P2₁/n space group with the crystal cell parameters a = 12.3160(19) ?, b = 21.067(3) ?, c = 15.837(3)?, β = 96.767°, V = 4080.6(11) ?³ and Z = 4. Graphical Abstract  Addition CrI2 to the lithium salt of N-N′-bis(2,6- diisopropylphenyl)-2,4-diketiminate in diethylether yields a Cr(II) iodide complex with a coordinated, solvated LiI salt. Herein we report the spectroscopic and structural characterization. An erratum to this article can be found at