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

• Bologna, Italy Dipartimento di Scienze Molecolari Agroalimentari, Università degli Studi di Milano, via Celoria 2, 20133 Milano, Italy 10.3762/bjoc.8.16 Abstract The chirality transfer in liquid crystals induced by two helical perylenequinones (namely, the natural compounds cercosporin and phleichrome

• essentially determined by the axial chirality (helicity) of the core of the perylenequinones. Keywords: chirality; conformational analysis; DFT calculations; helical twisting power; nematic liquid crystals; Introduction The phenomenon of chiral induction in nematic mesophases has been known for a long time

• configuration of the dopant: Enantiomers induce oppositely handed cholesterics. Only in the last few decades has the generation of cholesteric liquid crystals and the amplification of the molecular chirality observed upon doping nematic phases with chiral derivatives attracted great interest in the field of

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

• mesophases are relatively unknown in detail and differ strongly from those known for calamitic liquid crystals. In this paper symmetric and nonsymmetric five-ring salicylideneaniline-based bent-core mesogens are presented, and the effect of lateral substituents attached at the outer phenyl rings (F, Cl, Br

• corresponding molecular movements, is sensitive to variations in the molecular structure. Keywords: antiferroelectric smectic phases; bent-core mesogens; electro-optical behaviour; liquid crystals; salicylideneanilines; Introduction For a long time there was a general perception that molecules capable of

• compounds have been synthesized with various combinations of structural fragments, and thus, they represent a new subfield of liquid crystals. Generally speaking, these mesogens prefer to pack in layers so as to yield smectic phases. Due to their bent shape there is a lateral correlation of molecular

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

• effort has been expended on designing columnar liquid crystals with high hole mobilities. There are fewer examples of good liquid crystalline electron conductors, and most of those known can only be used in an oxygen-free environment [12][13]. However, the columnar phases of 1,4,8,11,15,18,22,25

• ][32]. Yields of phthalocyanines prepared by this route are generally poor and usually less than 25% [29][30][31][32]. This, together with the need for chromatographic purification, limits the scale on which metal-free phthalocyanine liquid crystals can be made. Such low yields are common for

• conformational space available to the intermediate, they would favour cyclisation. This phenomenon is clearly related to the effect of gem-dimethyl groups on the cyclisation of acyclic compounds (the Thorpe–Ingold effect) [37]. From the standpoint of making phthlocyanine-based liquid crystals, its importance is

Single enantiomer synthesis of α-(trifluoromethyl)-β-lactam

• Václav Jurčík,
• Alexandra M. Z. Slawin and
• David O'Hagan

Beilstein J. Org. Chem. 2011, 7, 759–766, doi:10.3762/bjoc.7.86

• some such motifs are emerging in new chemical entities licenced for the pharmaceuticals market, but also in organic materials area, e.g., liquid crystals [9]. Methodologies continue to emerge for the asymmetric introduction of the CF3 group [10][11][12][13]. In this contribution, we report a synthesis

Oxidative allylic rearrangement of cycloalkenols: Formal total synthesis of enantiomerically pure trisporic acid B

• Silke Dubberke,
• Muhammad Abbas and
• Bernhard Westermann

Beilstein J. Org. Chem. 2011, 7, 421–425, doi:10.3762/bjoc.7.54

• building block for the synthesis of dienes leading to nagilactones, 1b has been utilized for the preparation of ferroelectric liquid crystals [14][15]. Starting from (−)-1c a vast number of cyclohexene carboxylic acid-based natural products bearing additional alkyl substituents can be synthesized. These

The preparation of 3-substituted-1,5-dibromopentanes as precursors to heteracyclohexanes

• Bryan Ringstrand,
• Martin Oltmanns,
• Jeffrey A. Batt,
• Aleksandra Jankowiak,
• Richard P. Denicola and
• Piotr Kaszynski

Beilstein J. Org. Chem. 2011, 7, 386–393, doi:10.3762/bjoc.7.49

• been used as structural elements of liquid crystals [1][2][3][4][5][6] as well as antithrombotic and neuroprotectant agents [7][8]. Some thianes IV are found in petroleum distillates [9] and several have been used for the preparation of sulfones [7][10][11], sulfoxides [11][12], and sulfonium

• the development of polar, zwitterionic nematic liquid crystals having large longitudinal dipole moments for formulation of nematic materials with positive dielectric anisotropy [24][25]. The zwitterions consist of six-membered sulfonium rings attached to a boron cluster, either [closo-1-CB9H10]− or

• designed dielectrophiles that are important intermediates in the preparation of polar liquid crystals. In this context, we demonstrated the preparation of sulfonium derivatives 11c and 11d from dibromides 1c and 1d as precursors to such compounds. Other examples will be reported elsewhere. Methods for

Air-stable, recyclable, and time-efficient diphenylphosphinite cellulose-supported palladium nanoparticles as a catalyst for Suzuki–Miyaura reactions

• Qingwei Du and
• Yiqun Li

Beilstein J. Org. Chem. 2011, 7, 378–385, doi:10.3762/bjoc.7.48

• the most powerful tools for the preparation of unsymmetrical biaryl compounds [4] and has been applied to many areas, including pharmaceuticals, herbicides, and natural products, as well as in the fields of engineering materials, such as conducting polymers, molecular wires, liquid crystals and

Studies on Pd/NiFe₂O₄ catalyzed ligand-free Suzuki reaction in aqueous phase: synthesis of biaryls, terphenyls and polyaryls

• Sanjay R. Borhade and
• Suresh B. Waghmode

Beilstein J. Org. Chem. 2011, 7, 310–319, doi:10.3762/bjoc.7.41

• products, pharmaceutical intermediates, pesticides, advanced materials and liquid crystals [8][9][10]. These applications, in turn, have led to the production of biaryls and polyaryls on the industrial scale [11]. The Suzuki reaction is usually performed with homogeneous palladium catalysts in the presence

• , antithrombotic, anticoagulant and cytotoxic activities [44][45][46][47]. Polyphenyls are also an important structural element in liquid crystals and fluorescent compounds [48][49][50][51][52]. Terphenyls have been previously synthesized by the reaction of aryl- or benzylzinc reagents with functionalized biphenyl

Effects of anion complexation on the photoreactivity of bisureido- and bisthioureido-substituted dibenzobarrelene derivatives

• Heiko Ihmels and
• Jia Luo

Beilstein J. Org. Chem. 2011, 7, 278–289, doi:10.3762/bjoc.7.37

• ], liquid crystals [18], chiral crystals [19][20][21][22][23], or cyclodextrins (CDs) [24][25][26] in such a way that the chiral environment within the binding site has an influence on preferential reaction pathways, thus inducing stereoselective photoreactions. Along these lines, the di-π-methane (DPM

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

• oligopeptides can act as useful building blocks for chiral supramolecular liquid crystals [15][16]. Herein, we present the synthesis of amphiphilic dendritic peptides (ADPs) composed of an aspartic acid core and an aliphatic periphery, and their self-assembly which leads not only to organogels but also to

• liquid crystals. Results and Discussion Synthesis and characterization The amphiphilic dendritic peptides were synthesized convergently as depicted in Scheme 1 via standard EDCI coupling of N-carbobenzyloxy-L-aspartic acid and L-aspartic acid dodecyl ester (readily prepared by the esterification of

• characteristic of hexagonal columnar liquid crystals. The conic fan-shaped textures of G3 grow (Figure 6B), and no longer change at 50 °C (Figure 6C). Figure 7 shows the XRD scan for the birefringent phase of G3 at 50 °C. The birefringent phases of G3 were further confirmed as a hexagonal columnar liquid crystal

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

• impact of NPs on orientational ordering of LCs for appropriate concentrations of NPs is reminiscent to the influence of quenched random fields which locally enforce a biaxial ordering. Keywords: liquid crystals; nanoparticles; orientational order; quenched disorder; symmetry breaking; Introduction The

• are cases where the host component is a soft material [6]. These materials can then exhibit relatively strong responses, even to local low-energy excitations. Typical representatives of soft materials, with great application potential, are various liquid crystals phases [6]. Their soft character is

• spatially homogeneous structure is gradually attained. However, if impurities are present, they can pin the defects [12][13][14]. Consequently, the domain structure can be stabilized. In this contribution we study numerically a mixture of uniaxial nematic liquid crystals and rod-like NPs using a Lebwohl

Suzuki–Miyaura cross-coupling reaction of 1-aryltriazenes with arylboronic acids catalyzed by a recyclable polymer-supported N-heterocyclic carbene–palladium complex catalyst

• Guangming Nan,
• Fang Ren and
• Meiming Luo

Beilstein J. Org. Chem. 2010, 6, No. 70, doi:10.3762/bjoc.6.70

• ; recyclable catalyst; Suzuki–Miyaura reaction; Introduction The unsymmetrical biaryls feature in a diverse range of organic compounds, such as natural products, advanced materials, liquid crystals, ligands and molecules of medicinal interest [1][2][3][4]. The palladium-catalyzed Suzuki–Miyaura cross-coupling

Synthesis and crystallographic analysis of meso-2,3-difluoro-1,4-butanediol and meso-1,4-dibenzyloxy-2,3-difluorobutane

• Bruno Linclau,
• Leo Leung,
• Jean Nonnenmacher and
• Graham Tizzard

Beilstein J. Org. Chem. 2010, 6, No. 62, doi:10.3762/bjoc.6.62

• 1,3-C–F bonds are destabilised. As an application, liquid crystals have been prepared containing a vicinal difluoride motif [14][17][18]. Efficient stereodefined synthesis of vicinal difluoride moieties is not straightforward. Direct methods include fluorination of alkenes with F2 [19], XeF2 [20], or

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

• compared to the bulk situation, where the same material crystallizes into a polymorphic structure at 68 °C. Keywords: AFM; discotic liquid crystals; hexapentyloxytriphenylene; self-organization; thin films; Introduction Discotic liquid crystals are an interesting type of organic semiconductors that allow

• columns, which then behave like molecular wires. Their good performance makes them promising for use as transistors [3] in electronic circuits, for light emitting diodes [4] and in solar cells [5][6]. Liquid crystals (LCs) possess a long range, even if imperfect, order that is beneficial for creating a

• discotic liquid crystals in micrometer-sized regions of uniform planar alignment. The self-organizing nature of discotics is thus a powerful and promising tool for creating controlled nanometric or micrometric structures. Experimental HAT5 was dissolved in toluene at different concentrations and deposited

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

• of functional molecules that exploit these conformational effects will then be presented, drawing from a diverse range of molecules including pharmaceuticals, organocatalysts, liquid crystals and peptides. Keywords: conformation; functional molecules; organofluorine chemistry; stereochemistry

• novel liquid crystals. A distinguishing feature of compounds such as 54 is their stereochemical complexity. It is necessary to control these stereocentres during synthesis so that the conformational properties of different diastereoisomers can be compared. This has been explored with compounds

• 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

The subtle balance of weak supramolecular interactions: The hierarchy of halogen and hydrogen bonds in haloanilinium and halopyridinium salts

• Kari Raatikainen,
• Massimo Cametti and
• Kari Rissanen

Beilstein J. Org. Chem. 2010, 6, No. 4, doi:10.3762/bjoc.6.4

• in crystal engineering [18][19], and lately it has widely and successfully applied in other fields of material science, such as in supramolecular separations, liquid crystals, organic semiconductors and paramagnetic materials technologies [20][21]. Recently, the important role of XBs in biological

Competition between local disordering and global ordering fields in nematic liquid crystals

• Matej Cvetko,
• Milan Ambrožič and
• Samo Kralj

Beilstein J. Org. Chem. 2010, 6, No. 2, doi:10.3762/bjoc.6.2

• Department, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia 10.3762/bjoc.6.2 Abstract We study the influence of external electric or magnetic field B on orientational ordering of nematic liquid crystals or of other rod-like objects (e.g. nanotubes immersed in a liquid) in the presence of random

• disordered regime. Memory effects are apparent only in the latter case, i.e. for B < Bc. PACS numbers: 47.51.+a, 47.54.-r, 07.05.Tp, 61.30.-v Keywords: disorder; Imry-Ma theorem; liquid crystals; memory effect; orientational order; Introduction For years there has been a strong interest in the phase and

• structural behavior of randomly perturbed liquid crystals (LCs) [1]. Such systems could be used in various electro-optical applications. On the other hand they represent also an adequate testing ground [2] to study fundamental questions concerning the impact of disorder [3][4][5][6] on various phase and

Looking forward to volume six

• Jonathan Clayden

Beilstein J. Org. Chem. 2010, 6, No. 1, doi:10.3762/bjoc.6.1

• way within the journal, these papers can be viewed together using the “thematic series” tool on the website. Recent series have covered the topical themes of flow chemistry [1], supramolecular chemistry [2] and liquid crystals [3], and further series on carbohydrate chemistry and on organofluorine

Ring-alkyl connecting group effect on mesogenic properties of p-carborane derivatives and their hydrocarbon analogues

• Aleksandra Jankowiak,
• Piotr Kaszynski,
• William R. Tilford,
• Kiminori Ohta,
• Adam Januszko,
• Takashi Nagamine and
• Yasuyuki Endo

Beilstein J. Org. Chem. 2009, 5, No. 83, doi:10.3762/bjoc.5.83

• B) than for carbocyclic derivatives (C and D). Analysis indicates that this effect may have quadrupolar and conformational origin. Keywords: p-carborane; liquid crystals; structure-property relationship; Introduction During the past decade, we have been investigating mesogenic derivatives of p

• -carboranes A and B (Figure 1) in the context of fundamental and applied studies of liquid crystals and development of new materials for electrooptical applications [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. p-Carboranes belong to an extensive family of closo-boranes

• isostructural mesogenic derivatives of p-carboranes (A and B), bicyclo[2.2.2]octane (C), and benzene (D), we have been probing fundamental aspects of structure-property relationships in liquid crystals such as the effect of conformational properties [1][2], the structure of the linking group [5], and tail

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

• , indicating the alignment of two molecular axes along individual directors in the magnetic field. These observations may be rationalised with larger assemblies of V-shaped molecules isotropically distributed around the direction of the magnetic field. Keywords: biaxial nematics; liquid crystals; phase

• engineering; thiadiazoles; V-shaped mesogens; Introduction Most molecules forming nematic liquid crystals, the nematogens, are based on rod-shaped (calamitic), anisometric cores with peripheral flexible chains along the molecular long axis [1]. Nematic phases are the simplest liquid crystalline mesophases

• of a series of thiadiazoles of general structure II is presented and the successful approach to low temperature, enantiotropic nematic liquid crystals in the family of bent-shaped oligo(phenylene ethynylenes) will be discussed. Results and Discussion Synthesis The shape-persistent arms of the new

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

Influence of spacer chain lengths and polar terminal groups on the mesomorphic properties of tethered 5-phenylpyrimidines

• Gundula F. Starkulla,
• Elisabeth Kapatsina,
• Angelika Baro,
• Frank Giesselmann,
• Stefan Tussetschläger,
• Martin Kaller and
• Sabine Laschat

Beilstein J. Org. Chem. 2009, 5, No. 63, doi:10.3762/bjoc.5.63

• maximum phase width was observed for the C5 spacer regardless of the terminal group, whereas the hydroxy- and cyano-substituted derivatives 5 and 7, respectively, were non mesomorphic and showed only melting transitions. Keywords: calamitic; liquid crystals; 5-phenylpyrimidines; Introduction A

• tremendous amount of work has been done on calamitic liquid crystals, which has led to applications in the field of LC displays [1]. Among the large family of various calamitic mesogens 2-alkoxy-5-phenylpyrimidines 1 are prominent members due to the fact that the two nitrogen atoms increase the polarity of

• are possible, i.e. 4-, 5-, and 2-phenylpyrimidine, only the latter two are suitable for liquid crystals. Furthermore 5- and 2-phenylpyrimidines differ in their overall conformation. According to ab initio calculation by Barone [2], 2-phenylpyrimidine is almost planar, whereas 5-phenylpyrimidine has a

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

• using the imidazolium ring as a common element, has allowed us to tailor a new set of materials which associate specific functionalities. These functionalities are consequences of the original properties of the component, ionic liquids, liquid crystals and their association in a single compound. The

• ; supramolecular arrangement; Introduction Uniting the properties of ionic derivatives with those of liquid crystals, with their many forms of labile macroscopic ordering, raises interesting prospects [1]. By themselves ionic liquids are organic salts (i.e. totally composed of cations and anions) that are

• , none of these cations are as popular as the imidazolium ion. In particular, the modification of the N,N′ substituents in imidazolium systems is a facile mean of creating various amphotropic liquid crystals. Such imidazolium liquid crystals have especially great potential as ordered reaction media that

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

• special properties (in particular optical) that result from the unique combination of fluidity and long-range order of liquid crystals are interesting from different points of view. On the one hand, the LC can give the fibre new functionality, in particular sensitivity to temperature variations or to the

Saddle-shaped tetraphenylenes with peripheral gallic esters displaying columnar mesophases

• Eugen Wuckert,
• Constanze Hägele,
• Frank Giesselmann,
• Angelika Baro and
• Sabine Laschat

Beilstein J. Org. Chem. 2009, 5, No. 57, doi:10.3762/bjoc.5.57

• was detected. Keywords: columnar mesophases; discotic liquid crystals; tetraphenylene; Introduction Columnar liquid crystals have received increasing interest during the last decade due to their 1D charge transport and self-healing properties, which make them particularly promising candidates for

• anomalous odd-even effect is a more general phenomenon than previously thought. Investigations to extend this concept to other classes of liquid crystals are currently in progress. Experimental General Melting points were measured on a Mettler Toledo DSC822 and are uncorrected. NMR spectra were recorded on