Spin state switching in iron coordination compounds

• Philipp Gütlich,
• Ana B. Gaspar and
• Yann Garcia

Beilstein J. Org. Chem. 2013, 9, 342–391, doi:10.3762/bjoc.9.39

Formation of smectic phases in binary liquid crystal mixtures with a huge length ratio

• Nadia Kapernaum,
• Friederike Knecht,
• C. Scott Hartley,
• Jeffrey C. Roberts,
• Robert P. Lemieux and
• Frank Giesselmann

Beilstein J. Org. Chem. 2012, 8, 1118–1125, doi:10.3762/bjoc.8.124

Control over molecular motion using the cis–trans photoisomerization of the azo group

• Estíbaliz Merino and
• María Ribagorda

Beilstein J. Org. Chem. 2012, 8, 1071–1090, doi:10.3762/bjoc.8.119

• luminescent energy to mechanical energy. Ikeda et al. [37] demonstrated how the irradiation of a liquid-crystal elastomer (LCE) of azobenzenes with linearly polarized light is able to collapse and expand the LCE films (yellow sheet in Figure 20) in a certain direction. The film is obtained by thermal

• polymerization of the azocompound 23 (monomer), by using the diacrylate derivative 24 as a crosslinking agent. The azo-LCEs comprise a polydomain with the characteristics of a liquid crystal, formed by many microsized domains of azobenzene aligned in the same direction. Although macroscopically the direction of

• ). The consecutive irradiation with λ = 366 nm at 0°, −45°, −90° or −135° following by irradiation at λ = 540 nm produces the contraction and expansion of the film in the clockwise direction. Recently, this liquid-crystal elastomer was used in developing the first plastic photomechanical motor capable of

Perhydroazulene-based liquid-crystalline materials with smectic phases

• Zakir Hussain,
• Henning Hopf and
• S. Holger Eichhorn

Beilstein J. Org. Chem. 2012, 8, 403–410, doi:10.3762/bjoc.8.44

• formulation of various components, including about 15–20 individual LC molecules. The nematic (N) liquid crystal phase, with its orientational order only, is the most important mesophase; it is used in almost all commercially available LC displays. On the other hand, the smectic (Sm) LC phases, with their

• , although recently they have attracted considerable interest [9][10][11][12]. It has also been demonstrated that by modification of the basic structures a wide range of properties affecting the liquid crystal behavior of these materials can be changed. The core units presently used in most of the calamitic

• substituents and their substituent combinations, as well as on the stereochemistry at their central junction and the relative orientation of the respective substituents. Hydroazulene-based liquid-crystal molecules are expected to show mesogenic behavior if linearity exists in the system. Such linearity can be

Synthesis and mesomorphic properties of calamitic malonates and cyanoacetates tethered to 4-cyanobiphenyls

• Katharina C. Kress,
• Martin Kaller,
• Kirill V. Axenov,
• Stefan Tussetschläger and
• Sabine Laschat

Beilstein J. Org. Chem. 2012, 8, 371–378, doi:10.3762/bjoc.8.40

• ][8], for the construction of liquid crystal displays [9][10][11], or as anisotropic conductors [12][13]. Over the past few decades, a huge variety of organic calamitic compounds, which form nematic liquid crystals, have been synthesized and investigated [1][14]. Bulkin et al. were the first to

Liquid-crystalline nanoparticles: Hybrid design and mesophase structures

• Gareth L. Nealon,
• Romain Greget,
• Cristina Dominguez,
• Zsuzsanna T. Nagy,
• Daniel Guillon,
• Jean-Louis Gallani and
• Bertrand Donnio

Beilstein J. Org. Chem. 2012, 8, 349–370, doi:10.3762/bjoc.8.39

• organic ligand coating and their resulting phase behaviour. Mechanisms proposed to explain the supramolecular organisation of the mesogens within the liquid-crystalline phases are discussed. Keywords: hybrid; liquid crystal; mesogen; mesomorphism; mesophase; nanoparticle; self-organisation; supramolecule

• liquid crystal possess intrinsic directional order, often accompanied by various degrees of positional order, whilst remaining in a fluid state. A material that exhibits a liquid-crystalline state as a function of temperature is referred to as thermotropic, whereas those that exhibit a LC phase in the

• ligands on the NP surface are just as important as their chemical structure, or in other words, their mesogenic character. Synthesis of liquid-crystal–nanoparticle hybrids The synthesis of NP hybrids is of course largely determined by the nature of the nanoparticle, and is affected by factors such as the

Synthesis of oleophilic electron-rich phenylhydrazines

• Aleksandra Jankowiak and
• Piotr Kaszyński

Beilstein J. Org. Chem. 2012, 8, 275–282, doi:10.3762/bjoc.8.29

• preparation of a discotic liquid crystal. Results and Discussion Our initial attempts at the preparation of 3,4-dioctyloxyphenylhydrazine (1a) focused on deprotection of the trichloroethyl ester 3a under buffered reductive conditions, according to the general literature procedure [24]. In aqueous MeOH

The interplay of configuration and conformation in helical perylenequinones: Insights from chirality induction in liquid crystals and calculations

• Elisa Frezza,
• Silvia Pieraccini,
• Stefania Mazzini,
• Alberta Ferrarini and
• Gian Piero Spada

Beilstein J. Org. Chem. 2012, 8, 155–163, doi:10.3762/bjoc.8.16

• [1]. By addition of a chiral nonracemic compound, a nematic liquid crystal is transformed into a chiral nematic (or cholesteric) phase. Here the director, i.e., the local alignment direction, rotates in space in helical way, along a perpendicular axis [2][3]. The handedness of this helix reflects the

• 1 and 2 was measured in the liquid-crystal mixture E7 [30] at a temperature of 298 K. The values −12 μm−1 and +54 μm−1 were obtained for 1 and 2, respectively. The opposite sign observed for the two compounds clearly reflects their opposite configuration. The handedness of the induced cholesterics

• accounts for the stabilization of the conformer in the nematic environment and is defined as where Uj(Ω) is the orientational potential experienced by a dopant, in the orientation defined by the Euler angles Ω, inside the liquid-crystal phase [29][40]. Chemical structure of the helical perylenequinones

Laterally substituted symmetric and nonsymmetric salicylideneimine-based bent-core mesogens

• Sonja Findeisen-Tandel,
• Wolfgang Weissflog,
• Ute Baumeister,
• Gerhard Pelzl,
• H. N. Shreenivasa Murthy and
• Channabasaveshwar V. Yelamaggad

Beilstein J. Org. Chem. 2012, 8, 129–154, doi:10.3762/bjoc.8.15

• exhibiting liquid crystal (LC) phases have to be rodlike, so-called calamitic LCs. As is well known, such compounds exhibit nematic and smectic phases, which are commonly referred to as “calamitic phases”. However, the inherent fallacy of this notion was pointed out in the middle of the seventies when

Improved syntheses of high hole mobility phthalocyanines: A case of steric assistance in the cyclo-oligomerisation of phthalonitriles

• Daniel J. Tate,
• Rémi Anémian,
• Richard J. Bushby,
• Suwat Nanan,
• Stuart L. Warriner and
• and Benjamin J. Whitaker

Beilstein J. Org. Chem. 2012, 8, 120–128, doi:10.3762/bjoc.8.14

• that it provides a simple, high-yielding route to metal-free α-alkylated phthalocyanines. Liquid-crystal properties The liquid-crystal behaviour of the compounds we synthesised was investigated by polarising microscopy, differential scanning calorimetry (DSC) and, in the cases of compounds 7c–7e, by

• of theory) the space-filling properties of disordered/fluid n-alkyl and isoalkyl chains are expected to be “much the same”, there have been few studies of the differences between the liquid-crystal properties of n-alkyl and isoalkyl-substituted liquid-crystal derivatives. However, Gray and Kelly have

• -TRMC mobilities for liquid crystals that are as high as, or even higher than, that for 7c, a value of 0.14 cm2·V−1·s−1 is one of the very highest recorded for a macrodomain (time-of-flight) hole mobility of a liquid crystal. The reason why the mobilities of these α-alkylated phthalocyanines are this

Progress in liquid crystal chemistry II

• Sabine Laschat

Beilstein J. Org. Chem. 2012, 8, 118–119, doi:10.3762/bjoc.8.13

• Sabine Laschat Institut für Organische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany 10.3762/bjoc.8.13 It is a great pleasure to introduce this second Thematic Series on "Progress in liquid crystal chemistry" within the Beilstein Journal of Organic Chemistry. Why

• by Merck, the world’s largest supplier of liquid crystal materials for electro-optical applications. This increase of 38% on 2009 was attributed to the demand for liquid crystal displays (LCDs). Forecasts predict annual global shipments of over 268.8 million LCD television sets by 2014 [1]. However

• "Progress in liquid crystal chemistry" two years ago [5], the research field has further broadened and stretches currently from materials science, through energy conversion and storage, to life sciences. The interested reader might be directed to a very recent special issue of Liquid Crystals edited by John

Imidazole as a parent π-conjugated backbone in charge-transfer chromophores

• Jiří Kulhánek and
• Filip Bureš

Beilstein J. Org. Chem. 2012, 8, 25–49, doi:10.3762/bjoc.8.4

• [100] and its application in liquid-crystal media and devices was again summarized in a Merck patent in 2004 [101]. In 2004 and 2005, Carella, Centore, and co-workers utilized 2-amino-4,5-dicyanoimidazole 83 (for X-ray structure analysis, see [102]) in the synthesis of chromophores 84–86 featuring

Amphiphilic dendritic peptides: Synthesis and behavior as an organogelator and liquid crystal

• Baoxiang Gao,
• Hongxia Li,
• Defang Xia,
• Sufang Sun and
• Xinwu Ba

Beilstein J. Org. Chem. 2011, 7, 198–203, doi:10.3762/bjoc.7.26

• dendritic polyaspartic acid were designed and synthesized. The organogel and liquid crystal properties of these amphiphilic dendritic peptides were fully studied by field-emission SEM, temperature dependent FT-IR, differential scanning calorimetry, polarization optical microscopy and X-ray diffraction

• experiments. Amphiphilic dendritic peptides G3 show good organogel properties with a minimum gelation concentration as low as 1 wt %. Furthermore, amphiphilic dendritic peptides G3 can form a hexagonal columnar liquid crystal assembly over a wide temperature range. Keywords: amphiphilic; dendritic peptides

• ; liquid crystal; organogels; Introduction Peptide self-assembly has drawn a significant attention due to potential applications, especially in the fields of biomedicine and bionanotechnology [1][2][3]. Programmed self-assembly of peptides into highly ordered nanostructures creates biomaterials that

Symmetry breaking and structure of a mixture of nematic liquid crystals and anisotropic nanoparticles

• Marjan Krasna,
• Matej Cvetko and
• Milan Ambrožič

Beilstein J. Org. Chem. 2010, 6, No. 74, doi:10.3762/bjoc.6.74

• , even pure LC systems have found several applications, in particular in the electro-optics industry. We henceforth limit our attention to rod-like LC molecules and to thermotropic LCs in which liquid crystal phases are induced by lowering the temperature from the ordinary liquid (isotropic) phase. The

• nematic configuration represents the simplest liquid crystal phase [6]. In the bulk nematic phase LC molecules tend to be oriented homogeneously along a single symmetry breaking direction. At the mesoscopic level the average local orientational ordering is commonly described by the nematic director field

Self-assembled ordered structures in thin films of HAT5 discotic liquid crystal

• Piero Morales,
• Jan Lagerwall,
• Paolo Vacca,
• Sabine Laschat and
• Giusy Scalia

Beilstein J. Org. Chem. 2010, 6, No. 51, doi:10.3762/bjoc.6.51

• . R. Portici, P.le E. Fermi, I-80055 Portici (Naples) Italy Institute of Organic Chemistry, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany 10.3762/bjoc.6.51 Abstract Thin films of the discotic liquid crystal hexapentyloxytriphenylene (HAT5), prepared from solution via casting

• or spin-coating, were investigated by atomic force microscopy and polarizing optical microscopy, revealing large-scale ordered structures substantially different from those typically observed in standard samples of the same material. Thin and very long fibrils of planar-aligned liquid crystal were

• found, possibly formed as a result of an intermediate lyotropic nematic state arising during the solvent evaporation process. Moreover, in sufficiently thin films the crystallization seems to be suppressed, extending the uniform order of the liquid crystal phase down to room temperature. This should be

The C–F bond as a conformational tool in organic and biological chemistry

• Luke Hunter

Beilstein J. Org. Chem. 2010, 6, No. 38, doi:10.3762/bjoc.6.38

• liquid crystals. A liquid crystal is a fluid phase in which there is some orientational ordering of the molecules. Liquid crystal display (LCD) technology requires rod-shaped molecules that have a dipole moment perpendicular to the long axis of the molecule, and this is often achieved by incorporating

• fluorinated subunits into the liquid crystal molecule (Figure 14) [40]. In most cases (e.g. 57 and 58), the fluorine atoms act not as conformational control elements but simply as polar substituents. However, note that in the more sophisticated compound 59, the ring oxygens also contribute to the dipole

• molecular conformation as well as the molecular dipole moment. The difluoro compound 60 (Figure 15) can be viewed as a conceptual progression from the axially fluorinated liquid crystal 58. NMR and modelling data show that the fluoroalkyl chain of 60 adopts a zigzag conformation in which the two C–F bonds

Low temperature enantiotropic nematic phases from V-shaped, shape-persistent molecules

• Matthias Lehmann and
• Jens Seltmann

Beilstein J. Org. Chem. 2009, 5, No. 73, doi:10.3762/bjoc.5.73

• design a shape-persistent molecular scaffold of type I (Figure 2) based on oligo(phenylene ethynylene) building blocks. These molecules show liquid crystal behaviour only with a flat bending unit possessing a dipole along the apex of the mesogen, sufficiently long aliphatic chains R and at least one

• in Table 1. Interestingly, all phenylene ethynylene oligomers show exclusively enantiotropic nematic liquid crystal phases, even for the hockey stick shaped intermediates 3. However, the temperature intervals for the latter are small, approaching a maximum of 43 °C for compound 3c and melting in all

Molecular length distribution and the formation of smectic phases

• Nadia Kapernaum,
• C. Scott Hartley,
• Jeffrey C. Roberts,
• Robert P. Lemieux and
• Frank Giesselmann

Beilstein J. Org. Chem. 2009, 5, No. 65, doi:10.3762/bjoc.5.65

• by extensive out-of-layer fluctuations. Keywords: bidispersity; liquid crystals; phase diagrams; smectic phases; structure and dynamics; Introduction The classical (and highly successful) approach to systematically tailor liquid crystal materials for specific applications is the formulation of

• -difluorohexyloxy)pyridine (MDW510) [7] were synthesized according to published procedures and shown to have the expected physical and spectral properties. The liquid crystal 2-[4-(butoxy)phenyl]-5-(octyloxy)pyrimidine (2PhP) was obtained from a commercial source. X-Ray scattering experiments were performed with Ni

1-(4-Alkyloxybenzyl)-3-methyl-1H-imidazol-3-ium organic backbone: A versatile smectogenic moiety

• William Dobbs,
• Laurent Douce and
• Benoît Heinrich

Beilstein J. Org. Chem. 2009, 5, No. 62, doi:10.3762/bjoc.5.62

• William Dobbs Laurent Douce Benoit Heinrich Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, CNRS-Université de Strasbourg, BP 43, 23 rue du Loess, F-67034 Strasbourg Cedex 2, France 10.3762/bjoc.5.62 Abstract The merger of ionic liquid and liquid crystal fields, obtained by

• thermotropic liquid crystal behaviour. In association with different anions and in relation to the chain length incorporated in the methylimidazolium cations, we were able to tune the different transition temperatures and thus obtain stable smectic A phase from ambient temperature to 250 °C (decomposition

• , finally disappearing completely (Figure 4). This evolution will be more discussed later in regard to the results obtained with the dilatometry study. In summary, only 9 of the compounds did not show liquid crystal characteristics; 6n, which are constituted by the larger anion (bis[(trifluoromethyl

Coaxial electrospinning of liquid crystal-containing poly(vinylpyrrolidone) microfibres

• Eva Enz,
• Ute Baumeister and
• Jan Lagerwall

Beilstein J. Org. Chem. 2009, 5, No. 58, doi:10.3762/bjoc.5.58

• (vinylpyrrolidone) with the liquid crystal 4-cyano-4′-octylbiphenyl in its smectic phase as core material could be produced. The encapsulation leads to remarkable confinement effects on the liquid crystal, inducing changes in its phase sequence. We conducted a series of experiments to determine the effect of

• varying the relative flow rates of inner and outer fluid as well as of the applied voltage during electrospinning on these composite fibres. From X-ray diffraction patterns of oriented fibres we could also establish the orientation of the liquid crystal molecules to be parallel to the fibre axis, a result

• unexpected when considering the viscosity anisotropy of the liquid crystal kept in its smectic phase during electrospinning. Keywords: coaxial electrospinning; composite material; core-sheath fibres; liquid crystal; smectic phase; Introduction Electrospinning is a versatile process for producing nano- and

Novel banana-discotic hybrid architectures

• Hari Krishna Bisoyi,
• H. T. Srinivasa and
• Sandeep Kumar

Beilstein J. Org. Chem. 2009, 5, No. 52, doi:10.3762/bjoc.5.52

• and self-healing of defects owing to their dynamic nature. Furthermore, there has been considerable interest in the field of non-conventional low molar mass liquid crystals, especially in liquid crystal dimers because of their interesting mesomorphic properties. Liquid crystal oligomers serve as ideal

• , liquid crystal oligomers provide and stabilize a variety of fluid phases with fascinating functions and oligomeric approach provides a wide flexibility in the molecular design. The hybridization of above mentioned two varieties of liquid crystals may lead to novel nanostructured materials with

• in mind, we have designed and synthesized novel banana-discotic dimers. A typical five-ring banana liquid crystal and triphenylene based discotic [27] liquid crystals were chosen to prepare these novel dimers. Here we report the synthesis, characterization and phase behavior of these novel dimers

A convenient method for preparing rigid-core ionic liquid crystals

• Julien Fouchet,
• Laurent Douce,
• Benoît Heinrich,
• Richard Welter and
• Alain Louati

Beilstein J. Org. Chem. 2009, 5, No. 51, doi:10.3762/bjoc.5.51

• and fibres. These unique properties lead to their applications ranging from display technology through templating media for synthesis to biological activity (targeting and transporting of drugs and gene materials) [9]. Full convergence of the ionic liquid and liquid crystal fields could provide a vast

• structure is very close to a smectic type of organisation. The segregation between the alkyl tails and the charged rigid parts indicates that by melting the chains they could show liquid crystal behaviour at a higher temperature. In order to understand the influence of the anion on the electrochemical, UV

• the compounds was also demonstrated by the absence of significant perturbation of the DSC patterns following several heating–cooling cycles. Compounds 1e, not unexpectedly, do not show thermotropic behaviour, while the data for 1a–d give an order of anion stabilisation of liquid crystal behaviour of

Chiral amplification in a cyanobiphenyl nematic liquid crystal doped with helicene-like derivatives

• Alberta Ferrarini,
• Silvia Pieraccini,
• Stefano Masiero and
• Gian Piero Spada

Beilstein J. Org. Chem. 2009, 5, No. 50, doi:10.3762/bjoc.5.50

• Abstract The addition of a chiral non-racemic dopant to a nematic liquid crystal (LC) has the effect of transferring the molecular chirality to the phase organization and a chiral nematic phase is formed. This molecular chirality amplification in the LC provides a unique possibility for investigating the

• ; helicene; nematic liquid crystal; Surface Chirality model; Introduction Nematic liquid crystals (LCs) are fluid phases formed by anisometric molecules which, though free to rotate as in ordinary liquids, are preferentially aligned along a common axis, called director. The addition of a chiral non-racemic

• dopant to a nematic liquid crystal has the effect of transferring the molecular chirality to the phase organization and a chiral nematic (or cholesteric) phase is formed, in which the director rotates perpendicularly to an axis in a helical way (see Figure 1) [1]. For a given nematic host, the handedness

Progress in liquid crystal chemistry

• Sabine Laschat

Beilstein J. Org. Chem. 2009, 5, No. 48, doi:10.3762/bjoc.5.48

• organic light emitting diodes, photovoltaic devices, organic field effect transistors, gas sensors etc. [3][4][5][6][7][8]. One of the major issues in liquid crystal research today is still the poor knowledge of structure-property relationships and thus the synthesis of whole series of structurally

• related compounds is required in order to allow the design of liquid crystalline and other physical properties. It is the goal of this thematic series “Progress in Liquid Crystal Chemistry” to give the reader of Beilstein Journal of Organic Chemistry a flavor of the synthetic challenges of liquid crystal

• diverse topics such as phthalocyanine-fullerene hybrid materials for photovoltaic devices, functional metallomesogens, coaxial electrospinning of liquid crystal-containing microfibers, banana-discotic hybrid systems, ionic liquid crystals, relations between molecular length distribution and formation of