Liquid Crystalline Properties of Some Derivatives with a Long Lateral Alkoxyl Group

Abstract

This paper describes the liquid the crystalline properties of 4-(4-alkoxy-phenoxycarbonyl)phenyl 4-bromo-3-alkoxy-(2), 4-cyano-3-alkoxybenzoates(3), and 2-methyl-3-alkoxybenzoates(4). 2 and 3 are essentially smectogenic, while 4 are nematogenic. The difference in the mesomorphic properties is discussed in terms of their molecular geometrical characteristics estimated by a semi-empirical molecular orbital calculation.     

Synthesis and crystal structures of 2-amino-3-cyano-4-(2-chlorophenyl)-1,4-dihydro-2H-pyrano[3, 2-h]quinoline and 2-amino-3-cyano-4-(2-chlorophenyl)-8-(2-chlorobenzylidene)-1,4,5,6,7,8-hexahydrobenzo[b]pyran

The title compounds 2-amino-3-cyano-4-(2-chlorophenyl)-1,4-dihydro-2H-pyrano[3, 2-h]quinoline 1 (C₁₉H₁₂ClN₃O, M _r = 333.77) and 2-amino-3-cyano-4-(2-chlorophenyl)-8-(2-chlorobenzylidene)-1,4,5,6,7,8-hexahydrobenzo[b]pyran 2 were synthesized and crystallized. The crystals of compound 1 are triclinic, space group P-1, a = 7.488(2), b = 9.127(3), c = 12.252(3) Å, = 73.58(2), = 78.38(2)°, = 75.39(2), Z = 2, V = 769.5(4) ų; The compound 2 crystallizes in space group P2₁/n, with cell parameters a = 13.582(2), b = 8.974(1), c = 16.960(2) Å, = 103.34(1)° and D _calc = 1.352 g/cm^–3 for Z = 4. X-ray analysis reveals that atoms C(1)—C(5) and O form a pyran ring in compound 1, which adopts half-chair conformation. In compound 2 the atoms C(12)—C(16) and O form a pyran ring which adopts boat conformation, another six-membered ring (C(8)—C(13)) adopts a half-chair conformation. In addition, there are intermolecular hydrogen bonds in the crystal structures 1 and 2.     

Photooxygenation of 2-amino-3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophene

The photooxygenation of 2-amino-3-cyano-4,5,6,7-tetrahydro-benzo[b]thiopene1 was carried out in the presence of thiourea in order to reductively trap the intermediate; however, the rearranged compound 3-cyano-7-hydroxy-2-thio-2,4,5,6,7,7a-hexahydroindole2 was isolated. The structure, determined by X-ray crystallography, is described, and the mechanism for the formation of2 is discussed.     

Efficiency Enhancement of Polymer Solar Cells with Three-Component Active Layer

The photvoltaic performance of polymer solar cell (PSC) with a three-component active layer was studied. The incorporation of 4-cyano-4’-octylbiphenyl (8CB) as an additive to a P3HT [poly(3-hexylthiophene)]:PC₆₁BM [[6,6]-phenyl-C61-butyric acid methyl ester] blend film led to a higher absorbance, larger crystal size, closer packing of P3HT, and hence enhanced hole mobility. The power conversion efficiency of the PSC with the three-component active layer (P3HT: PC₆₁BM:8CB blend film) was improved by over 30% compared to that of the reference device without 8CB, due to an enhancement in all parameters such as short circuit current, open circuit voltage and fill factor.     

Synthesis,structures, and luminescent properties of a series of coordination compounds based on O,N-donor ligands

Four novel coordination compounds, namely, [Cd₂(pydc)₂(bpp)₂(H₂O)₂]? bpp?2H₂O (1), [Zn(Hpydc)₂]?3H₂O (2), [Cd(dhb)₂(phen)₂] (3), and [Zn(L)(phen) (H₂O)] (4) (H₂pydc?=?2,6-pyridinedicarboxylic acid, Hdhb?=?2,6-dihydroxybenzoic acid, H₂L?=?5-((2'-cyano-1,1'-biphenyl-4-yl) methoxy)isophthalic acid, bpp?=?1,3-bis(4-pyridyl)propane, and phen?=?1,10-phenanthroline) have been hydrothermally synthesized and characterized by IR spectroscopy, thermogravimetric analysis and X-ray single crystal diffraction analyses. Compounds 1, 2 and 3 feature zero-dimensional (0D) structures and 1 is further extended to one-dimensional (1D) chain structure through C-H???O hydrogen bonding interactions. Compound 4 exhibits 1D chain structure. The luminescent properties of compounds 3 and 4 have also been studied.     

Synthesis and crystal structure of 5-amino-4-cyano-1-[(5-methyl-1-t-butyl-4-pyrazolyl)carbonyl]-3-methylthio-1H-pyrazole

The title compound, 5-amino-4-cyano-1-[(5-methyl-1-t-butyl-4-pyrazolyl)carbonyl]-3-methylthio-1H-pyrazole 5, was synthesized by the treatment of 4 (5-methyl-1-t-butylpyrazole-4-carbohydrazide) with 2-cyano-3, 3-dimethylthio-acrylonitrile, and its crystal structure was determined by X-ray diffraction method. The crystal belongs to monoclinic, space group P2₁/c with unit cell parameters a = 13.566(4) Å, b = 10.833(3) Å, c = 11.202(3) Å, α = 90°, β = 98.073(5)°, γ = 90°, V = 1629.9(8) ų, Z = 4, D _c = 1.298, M _r = 318.40, μ = 0.210 mm⁻¹, F(000) = 672, R ₁ = 0.0488 and wR ₂ = 0.1250.     

The Synthesis of Deuteriated 4-n-Alkyl-4′-Cyanobiphenyls

A single synthetic route for chain-deuteriated, totally ring-deuteriated, or per-deuteriated 4-n-alkyl-4′-cyanobiphenyls has been developed. This new route gives better yields than the previously reported route for the synthesis of 4-cyano-4′-n-pentyl-d₁₁-biphenyl and also eliminates the main “impurity” present in the final product. The synthesis of 4-cyano-4′-n-pentyl-d₁₁-2′,3′,5′,6′-tetradeuteriobiphenyl is also reported.     

The structure of 2-amino-3-cyano-4-(4-methylphenyl)-6-methoxyl-1,4,9,10-tetrahydrobenzo[<Emphasis Type="Italic">f</Emphasis>]chromene

The X-ray crystal structure of 2-amino-3-cyano-4-(4-methylphenyl)-6-methoxyl-1,4,9,10-tetrahydrobenzo [f]chromene 1, C₂₂H₂₀N₂O₂, is determined. The crystals of compound 1 are triclinic, space group P-1, a = 10.120(1), b = 13.127(1), c = 15.203(2) Å, = 67.841(9), = 80.81(1), = 77.58(1), Z = 4, V = 1819.7(4) ų. It is interesting that all the atoms of the pyran ring are coplanar, which is different from other similar compounds. The structure is stabilized by intermolecular hydrogen bonds.     

Effect of Particle Size on Electro-Optic Properties of Liquid Crystal Devices Doped with γ-Cyclodextrin Stabilized Barium Titanate Nanoparticles

Barium titanate stabilized by γ-cyclodextrin nanoparticles were prepared by using a microwave reactor equipped with ultrasonic nozzle mixing at 240°C in a tetraethylene glycol solution of barium ethoxide and titanium ethoxide in the presence of γ-cyclodextrin. Particles in γ-cyclodextrin-stabilized BaTiO₃ nanoparticles had an average diameter of 2.1 nm and mainly distributed within the range of about 1 to 4 nm. The γ-cyclodextrin-stabilized BaTiO₃ nanoparticles were mixed with 4-cyano-4′-pentylbiphenyl at room temperature resulting in a liquid crystal sol of 4-cyano-4′-pentylbiphenyl. The response time of liquid crystal devices in the presence of γ-cyclodextrin-stabilized BaTiO₃ nanoparticles was faster than that in the absence.     

The hydrogen bonding in 2-amino-3-cyano-4-(3-nitrophenyl)-4,6-dihydro-5H-pyrano[3,2-c]quinolin-5-one N,N-dimethylformamide solvate monohydrate

The crystal structure of 2-amino-3-cyano-4,6-dihydro-4-(3-nitrophenyl)-5H-pyrano[3,2-c]quinolin-5-one N,N-dimethylformamide solvate monohydrate is determined by room temperature X-ray diffraction. The title compound 1, C₂₂H₂₁N₅O₆, is triclinic, space group P-1, a=9.109(2) ?, b=11.340(2) ?, c=12.485(2) ?, α=70.02(1)°, β=69.36(1)°, γ=67.32(1)°, Z=2, V=1081.4(4) ?³. It is interesting that a bridge-like hydrogen bond O–H···O is formed between the title compound and solvent molecules of water with molecular ratio of 2:2 building a bi-layer framework. In addition, there are two other types of classical hydrogen bonds N–H···N and N–H···O in the crystal structure.Supplementary material Crystallographic data for the structure reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication no. CCDC-275001. Copies of available material can be obtained, free of charge, on application to the Director, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK, (fax: +44-(0) 1223–336033 or e-mail: deposit@ccdc.cam.ac.uk).     

New Mesogenic Compounds Exhibiting a Thermotropic Optically Isotropic Phase

Abstract

The only two series of carboxylic acids, 3-nitro- or 3-cyano-4-alkoxybiphenyl-4′-carboxylic acid, are known to exhibit the optically isotropic phase (S_D). Now we synthesised 4-(branched alkoxy)-anilinebenzylidene-4′-carboxylic acid series, all being racemic, and investigated their mesophase properties by means of DSC, optical microscopy and X-ray measurement. As a result, some branched azomethine derivatives were found to form a S_D phase. We also synthesised cinnamic acid derivatives with branched alkoxy tail that were turned out to exhibit either S_D phase or hexagonal columnar phase. We tried biphenyl or azobenzene core analogues which were found to produce a highly ordered smectic phase or no mesophase, respectively. At this stage, we suppose it plays an important role that the branch is introduced into the terminal chain and a certain dipole moment is located within the mesogenic core. These factors may allow the peculiar molecular packing that causes an optically isotropic property.     

Synthesis of 1,2-dimethoxy-1,2-di(pyridin-2-yl)-1,2-ethanediol: Crystal and molecular structure determination

The compound, 2-hydroxy-[1,2-di(pyridin-2-yl)]ethane-1-one, 1, was isolated from the reaction of 2-pyridinecarboxaldehyde and 2-pyridinemethanol at 140°C without catalyst or solvent and characterized by¹H-NMR and IR spectral data. The compound 1 was treated with ethyl acetate to produce the 1,2-di(pyridin-2-yl)ethane-1,2-dione, 2. When 2 was dissolved in an excess of CH₃OH, crystals of 1,2-dimethoxy-1,2-di(pyridin-2-yl)-1,2-ethanediol, 3, were obtained. The molecular and crystal structure of 3 was determined by single crystal X-ray diffraction. The compound crystallizes in the monoclinic system belonging to the P2₁/n space group with a = 6.867(2) ?, b=9.546(4) ?, c=10.522(5) ?, α=90°, β=98.48(4)°, γ=90°. The asymmetric unit comprises two molecules of 3. Although the di-hemiketal was obtained in crystal form, it was found to be unstable, because its IR spectrum changed after a short time, indicating that it had been converted back to the original diketone, 2. The IR showed signals at 1713, and 1690 due to νC =O assigned to di-ketone group.     

Synthesis and Crystal Structure of the Salt [PPN+]2[Cu2I2Cl2]2−

Abstract The synthesis of the PPN (PPN=Ph₃P=N=PPh₃) salt of di-μ-iodo-dichlorocuprate (I) anion [Cu₂I₂Cl₂]²⁻ is described and the crystal and molecular structures of this compound are reported. It was found that the compound has the formula [PPN]₂[Cu₂I₂Cl₂]_0.7[Cu₂I₄]_0.3 (3). Compound 3 crystallizes in an orthorhombic crystal system, space group Pbca, with a = 19.654(3), b = 16.130(2), c = 20.108(3) ?, V = 6374.3(16) ?³ and Z = 4. The crystal contains 70% [Cu₂I₂Cl₂]²⁻ anions and 30% [Cu₂I₄]²⁻ anions. This was also confirmed by MSES spectroscopy. The anion [Cu₂I₂Cl₂]²⁻ is planar and the Cu atoms have a trigonal planar configuration. Graphical abstract Synthesis and Crystal Structure of the Salt [PPN ⁺ ] ₂ [Cu ₂ I ₂ Cl ₂ ] ²⁻ Andrey A. Yakovenko, Tatiana V. Timofeeva and Mikhail Yu. Antipin The title compound was synthesized and structurally investigated. The crystal contains 70% [Cu₂I₂Cl₂]²⁻ anions and 30% [Cu₂I₄]²⁻ anions. This was confirmed by MS ES spectroscopy.      

Molecular and crystal structures of 2-amino-5-benzoyl-4-(2-nitrophenyl)-3-cyano-4,5-dihydrothiophene

The crystal structure of 2-amino-5-benzoyl-4-(2-nitrophenyl)-3-cyano-4,5-dihydrothiophene is determined by X-ray diffraction analysis. The unit cell parameters are as follows: a = 10.878(2) Å, b = 12.890(3) Å, c = 13.539(4) Å, α = 108.15(2)°, β = 99.26(2)°, γ = 107.13(2)°, V = 1656(2) ų, d _calcd = 1.410 g/cm³, Z = 4, and space group P1ˉ. The molecules occupy two systems of independent positions in the crystal. Similar to the compounds studied earlier in this series, the o-nitrophenyl substituent has a synperiplanar orientation relative to the hydrogen atom at the C(4) atom of the heterocycle. __________ Translated from Kristallografiya, Vol. 45, No. 2, 2000, pp. 282–285. Original Russian Text Copyright ? 2000 by Nesterov, Kuleshova, Samet, Shestopalov.     

Structure of Three Related Diphosphorus Ligands: Highlighting the Significance of the Backbone

Abstract  

The three compounds contained in this report—4,6-bis(diphenylphosphino)-10,10-dimethylphenoxasilin (sixantphos), 1; 4,5-bis(diphenylphosphino)-9-isopropylidenexanthene, (isopropxantphos) 2 and bis-(2-diphenylphosphino)-p-tolyl) ether (PTEphos) 3, all contain a common ether-linked diphenylphosphino backbone. These structures are of interest with respect to the intra-molecular P···P distance which is 3.884(2), 4.104(2) and 5.151(2) ? for 1, 2 and 3 respectively. The differences in the P···P distances are as a result of the variations in the backbones. Structure 1 shows a significant roof-like bending of the backbone along the axis of planarity involving the oxygen and Si donor atoms. Compound 2 is also folded with a larger dihedral angle of 35.85(2)° as compared to 24.14(2)° found in 1. The backbone in structure 3 is significantly bent and twisted with a dihedral angle of 67.34(2)°. These data show the effect on the intra-molecular P···P distance of varying the backbone of three xantphos-type ligands, with respect to the nature of the heterocycle donor 1, the substituent on the donor 2 and total loss of xanthene character 3.     

Reaction of Triangular Cluster Complex Triiron Enneacarbonyl Disulfide with 1,2-bis(diphenylphosphino)ethane

Reaction of Fe₃(μ₃-S)₂(CO)₉ (A) with 1,2-bis(diphenylphosphino)ethane (Ph₂PCH₂CH₂PPh₂, dppe) in the presence of the decarbonylating agent Me₃NO·2H₂O in MeCN at room temperature afforded [Fe₃(μ₃-S)₂(CO)₈]₂(Ph₂PCH₂CH₂PPh₂) (1) containing bridging diphosphine ligand in 50% yield. The title complex 1 was structurally characterized by IR and NMR spectroscopic analysis. In addition, the molecular structure of 1 was further determined by X-ray crystallography. The molecule is centrosymmetric and the phosphorus atoms of DPPE reside in a basal position of the square-pyramidal geometry of the iron atoms.     

X-ray diffraction, DFT, and spectroscopic study of N , N ′-difluoroboryl-5-(2-thienyl)dipyrrin and fluorescence studies of related dipyrromethanes, dipyrrins and BF2-dipyrrins and DFT conformational study of 5-(2-thienyl)dipyrrin

To explore the characteristics of potential fluorescent probes that could be used to screen prospective HDS catalysts, new 5-thienyl dipyrromethene derivatives have been prepared. 5-(2-thienyl)- (1a), 5-(3-thienyl)- (1b), and 5-(3-(2,5-dibromothienyl))-dipyrromethane (1c), were oxidized with DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone) separately to give the corresponding dipyrrins 2a–2c. These were subsequently treated with F₃B·OEt₂ to afford the respective N,N′-difluoroboryl-5-(thienyl)dipyrrin compounds, 3a–3c; the latter two may serve as polymer precursors. Significant fluorescence signal enhancement is achieved with 3a–3c over 2a–2c. Orange fluorescence is observed for 3a whereas its isomer 3b gives green fluorescence (365 nm). An X-ray diffraction study of 3a was performed (orthorhombic, P2₁2₁2₁, a=10.684(10) ?, b=15.208(13) ?, c=7.256(6) ?, V=1179.0(17) ?³, Z=4, R ₁=0.0428, wR ₂=0.0686) and its geometry was studied by way of DFT (Gaussian 03; B3LYP/6-31G^*) to give a HOMO/LUMO energy level difference of 414 nm, and a 2-thienyl group rotational barrier of ∼6 kcal/mol, compared to that of ∼12 kcal/mol for the phenyl derivative. Theoretical modeling of 2a demonstrated that the [N–H⋯N] interaction is favored by ca. 10 kcal/mol, whereas [N–H⋯S] bonding is sterically unattainable.     

1:2 and 2:1 Stoichiometric Inclusion Complexes of 1,1,6,6-Tetraphenylhexa-2,4-diyne-1,6-diol and p-Anisaldehyde

Abstract  

1:2 and 2:1 stoichiometric complexes of 1,1,6,6-tetraphenylhexa-2,4-diyne-1,6-diol (DD) and p-anisaldehyde were presented in this paper. 2:1 inclusion complex of DD with p-anisaldehyde (denote 1) was fortuitously obtained from the volatile oil of medicine herb Zanthoxylum schinifolium Sieb.et Zucc. 1:2 inclusion complex of DD with p-anisaldehyde (denote 2) was obtained under ordinary crystallization conditions. The results of single crystal X-ray diffraction show that complex 1 is triclinic, space group Pī, whereas the complex 2 is monoclinic, space group P2₁/n. In the complex of 1, 1D zigzag ribbon host framework is constructed through a closed hydrogen bonding network formed by DD molecules themselves and p-anisaldehyde molecules are accommodated into the tunnel enclosed by 1D zigzag ribbons. In the complex of 2, DD and p-anisaldehyde are connected with each other via hydrogen bonding, forming a layer-type structure. DD molecule exhibits gauche conformation in complex 1 and antiperiplanar conformation in complex 2, which are regarded as supramolecular conformation stereoisomers.     

Synthesis and structure of a novel copper (II) nitrate complex of 2,4-dioxo-4-phenylbutanoic acid

2,4-Dioxo-4-phenylbutanoic acid, 1, was synthesized as a biproduct of the attempted synthesis of 1,6-bisphenyl-1,3,4,6-hexanetetrone. Crystals of [Cu(H2O)(bipy) (L)][Cu(bipy)(L)(NO3)] (H2O)(NO3) (L = 2,4-dioxolato-4-phenylbutanoic acid and bipy = 2,2′-bipyridine), 2, were grown by slow evaporation of a solution of Cu(NO₃)₂·3 H₂O, 2,2′-bipyridine, and 1 in a mixture of ethanol and water. The compound crystallized in the triclinic space group P-1 and is made up of two distinct molecular units each with approximately square pyramidal geometry: a = 10.663(2) ?, b = 13.275(3) ?, c = 15.071(3) ?, α = 80.26(3)°, β = 74.13(3)°, γ = 89.12(3)°. The copper ions are chelated by molecules of 1 and molecules of bipyridine. The molecular units are arrayed in rows held together by pi-stacking interactions and hydrogen bonding.     

Oxazoles XXI. Three Ester Ammonium Salts Resulting from the Rupture of an Oxazoline Ring

Abstract  

The synthesis and characterisation of three ammonium salts that are formed via a ring opening of a 2-oxazoline (i.e., a 4,5-dihydro-1,3-oxazole) are described. Compound 1, derived from 2-phenyl-2-oxazoline (Phox), was isolated as a major reaction product during an unrelated synthesis using Phox which was being carried out in the presence of NO₃ ⁻ ions. The isolated compound is identified as the nitrate salt of the terminal ammonium ester [H₃NCH₂CH₂OC(=O)Ph]⁺ (1). The X-ray crystal structure (C₉H₁₂N₂O₅) of 1 is revealed to be orthorhombic (space group Pna2₁) with a = 21.1304(8), b = 7.5975(2) and c = 6.8629(3)?. The analogous material 2a, obtained from the related oxazole 4,4-dimethyl-2-phenyl-2-oxazoline (MePhox) under identical conditions to that of 1, contains the [H₃NCMe₂CH₂OC(=O)Ph]⁺ cation. The X-ray crystal structure (C₁₁H₁₆N₂O₅) of 2a is monoclinic with a = 6.1270(3), b = 6.3603(3), c = 16.1632(8)? and β = 90.662(3)o and of space group P2₁. Chiral derivative 2b, was isolated from a wet CH₂Cl₂/THF solution upon treatment of MePhox with (S)-mandelic acid. This material was shown to also contain the [H₃NCMe₂CH₂OC(=O)Ph]⁺ cation, a lattice water molecule and an (S)-mandalate anion. The X-ray crystal structure of 2b (C₁₉H₂₃NO₅·H₂O) is orthorhombic (space group P2₁2₁2₁) with a = 6.4733(3), b = 11.4661(5) and c = 24.5791(11)?. One proposed mechanism by which all three materials are formed was first presented in seminal work by Deslongchamps. The compounds reported herein are representatives of a class of rarely isolated intermediates in heterocyclic ring opening reactions and they are also the first examples of (ω-ammoniumethyl)(aryl) esters to be structurally characterised.