Supercritical carbon dioxide: a solvent like no other

• Jocelyn Peach and
• Julian Eastoe

Beilstein J. Org. Chem. 2014, 10, 1878–1895, doi:10.3762/bjoc.10.196

• hydrotropic salts and phenols to microemulsions can lead to positive viscosity builds in both water-in-oil and water-in-carbon dioxide systems as observed by Eastoe et al. and John et al. [40][94][104] Emerging areas using supercritical CO2 Bicontinuous and lamellar phases, lamellar liquid crystals and foams

The influence of intraannular templates on the liquid crystallinity of shape-persistent macrocycles

• Joscha Vollmeyer,
• Ute Baumeister and
• Sigurd Höger

Beilstein J. Org. Chem. 2014, 10, 910–920, doi:10.3762/bjoc.10.89

• planar. Keywords: discotic liquid crystals; shape-persistent macrocycles; templates; X-ray scattering; Introduction The supramolecular chemistry of shape-persistent macrocycles has enormously expanded during the past several years [1][2][3][4][5][6]. It covers the non-covalent interaction between the

• naphthylene corners allow an efficient surrounding of the macrocycles with an alkyl fringe, according to the general design principle for discotic liquid crystals [47]. In addition to the macrocycles with intraannular bridges, we also synthesized and investigated a corresponding compound with an empty

• transition of liquid crystalline dimers and bent-core liquid crystals which has recently been identified as a nematic–twist bent nematic (NTB) transition (see, e.g., [59][60]). Therefore the nature of the phase change indicated by the DSC measurements could not be clarified yet. The X-ray pattern for the

Unusual polymorphism in new bent-shaped liquid crystals based on biphenyl as a central molecular core

• Anna Kovářová,
• Svatopluk Světlík,
• Václav Kozmík,
• Jiří Svoboda,
• Vladimíra Novotná,
• Damian Pociecha,
• Ewa Gorecka and
• Natalia Podoliak

Beilstein J. Org. Chem. 2014, 10, 794–807, doi:10.3762/bjoc.10.75

• dielectric measurements. The dielectric spectroscopy data are unique and presented for the first time in the SmCG phase providing new information about the molecular dynamics. Keywords: bent-shaped; biphenyl core; liquid crystals; mesomorphic behaviour; SmCG phase; Introduction Achiral bent-shaped liquid

• ], semifluorinated alkyl chains [14][20], and fullerene [21] into the terminal chain(s), variation of the linkage groups [10][22][23][24] (ester, azo, azoxy, imine, H-bond, cinnamoyl). Also dimeric, dendritic, and polymeric liquid crystals possessing the biphenyl moiety in the centre of the bent mesogenic unit were

• series of materials IV–VI, we utilized lengthening arms of phenols 7a–c and two-ring acids 8–10. All intermediates were obtained previously by known methods [47][48][49]. The bent-shaped liquid crystals I–III were synthesized in three steps (Scheme 1). The protected acids 1a,b were esterified with

Triphenylene discotic liquid crystal trimers synthesized by Co₂(CO)₈-catalyzed terminal alkyne [2 + 2 + 2] cycloaddition

• Bin Han,
• Ping Hu,
• Bi-Qin Wang,
• Carl Redshaw and
• Ke-Qing Zhao

Beilstein J. Org. Chem. 2013, 9, 2852–2861, doi:10.3762/bjoc.9.321

• mesomorphism. Keywords: Co2(CO)8 catalyzed cycloaddition; columnar mesophase; discotic liquid crystal; triphenylene; oligomer; Introduction Discotic liquid crystals (DLCs) with nematic phase have been commercially utilized in the liquid crystal display industry as optical compensating films for widening the

Synthesis of guanidinium–sulfonimide ion pairs: towards novel ionic liquid crystals

• Martin Butschies,
• Manuel M. Neidhardt,
• Markus Mansueto,
• Sabine Laschat and
• Stefan Tussetschläger

Beilstein J. Org. Chem. 2013, 9, 1093–1101, doi:10.3762/bjoc.9.121

• Martin Butschies Manuel M. Neidhardt Markus Mansueto Sabine Laschat Stefan Tussetschlager Institut für Organische Chemie, Universität Stuttgart, Pfaffenwalring 55, 70569 Stuttgart, Germany 10.3762/bjoc.9.121 Abstract The recently introduced concept of ionic liquid crystals (ILCs) with

• sulfonimide anion directly attached to the mesogenic unit. Keywords: anion exchange; ionic liquid crystals; ion pairs; mesophases; sulfonimides; Introduction While ionic liquids, i.e., molten salts composed of either organic cation or anion (or both) with melting points far below 100 °C, are extensively

Synthesis and structure of trans-bis(1,4-dimesityl-3-methyl-1,2,3-triazol-5-ylidene)palladium(II) dichloride and diacetate. Suzuki–Miyaura coupling of polybromoarenes with high catalytic turnover efficiencies

• Jeelani Basha Shaik,
• Venkatachalam Ramkumar,
• Babu Varghese and
• Sethuraman Sankararaman

Beilstein J. Org. Chem. 2013, 9, 698–704, doi:10.3762/bjoc.9.79

• find application in the areas of molecular electronics, organic discotic liquid crystals and OLEDs [24][25]. One of the ways to approach the synthesis of these interesting compounds is to carry out multiple C–C coupling reactions with suitable polybromoarene derivatives. In multiple C–C coupling

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

A new family of four-ring bent-core nematic liquid crystals with highly polar transverse and end groups

• Kalpana Upadhyaya,
• Venkatesh Gude,
• Golam Mohiuddin and
• Rao V. S. Nandiraju

Beilstein J. Org. Chem. 2013, 9, 26–35, doi:10.3762/bjoc.9.4

• -core mesogens; cyanobiphenyl; dipole moment; liquid crystals; nematic phase; polarity; Introduction Following the discovery of chiral and polar properties of mesomorphic bent-core compounds [1][2][3][4][5][6] the area of design, synthesis and properties of banana or bent-shaped liquid crystals (LC

• ~1606 cm−1, C=C stretching of an aromatic ring 1490 cm−1 and C–O–C stretching of an ester at ~1290 and ~1170 cm−1. The importance of the resorcylidene aniline core, present in calamitic ferroelectric liquid crystals [49][50][51][52][53], apparently seems superior to that of the benzylidene aniline core

Efficient electroorganic synthesis of 2,3,6,7,10,11-hexahydroxytriphenylene derivatives

• Carolin Regenbrecht and
• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2012, 8, 1721–1724, doi:10.3762/bjoc.8.196

• common structural motif. The use of triphenylenes in discotic liquid crystals [1][2] as building blocks in supramolecular chemistry [3][4] as well as in solid-state chemistry [5] is well documented. Furthermore, triphenylenes are applied as components of functional polymers [6][7] and fluorescent labels

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

• phase of the longer mesogen was identified as a smectic F phase. Keywords: bidispersity; liquid crystals; phase diagrams; smectic phases; smectic F phase; structure and dynamics; Introduction The mixing of different liquid crystals is a common technique to tailor their properties for specific

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

• conformational changes in polymers. There may also be variations in the organization of large assemblies of molecules in gels or liquid crystals. When polarized light is used, the photoisomerization often induces a reorganization of chromophores that can be reflected in the circular dichroism spectra. The basic

• photoswitch is a part of a macromolecular structure. A variety of photosensitive devices, such as smart polymers [36][37], liquid crystals [38][39], intelligent enzymes [40], and various switches and molecular machines [41][42][43][44][45][46][47][48], have been developed by using the photochromic properties

meta-Oligoazobiphenyls – synthesis via site-selective Mills reaction and photochemical properties

• Raphael Reuter and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2012, 8, 877–883, doi:10.3762/bjoc.8.99

• reduction of ~3.5 nm rendering it an ideal candidate for changing spatial arrangements on the molecular level. This change has been featured in a variety of applications [7][8][9], such as, switchable sensors [10], ion channels [11], catalysts [12], or liquid crystals [13]. In most of these applications

Synthesis of 2,6-disubstituted tetrahydroazulene derivatives

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

Beilstein J. Org. Chem. 2012, 8, 693–698, doi:10.3762/bjoc.8.77

• route by using carbene adduct intermediates. The protocol can be applied for the construction of functionalized hydroazulene skeletons as key components of many natural products as well as the core system of novel liquid-crystalline materials. Keywords: carbene addition; hydroazulenes; liquid crystals

Liquid-crystalline heterodimesogens and ABA-heterotrimesogens comprising a bent 3,5-diphenyl-1,2,4-oxadiazole central unit

• Govindaswamy Shanker,
• Marko Prehm and
• Carsten Tschierske

Beilstein J. Org. Chem. 2012, 8, 472–485, doi:10.3762/bjoc.8.54

• bent-core mesogens are of special interest for achieving biaxial nematic phases of the orthorhombic type. The orthogonal (NcybA) and skewed (NcybC) cybotactic nematic phases were distinguished by XRD and optical observations. Keywords: bent-core mesogens; cybotactic nematic phases; dimesogen; liquid

• crystals; 1,2,4-oxadiazoles; trimesogen; Introduction Liquid-crystalline (LC) dimers of low-molar-mass compounds formed by the coupling of two mesogenic segments are of contemporary interest [1][2][3][4]. These compounds exhibit fascinating properties, often different from the single mesogens, and they

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

• narrow temperature ranges. The dependence of the mesogenic behavior of the new materials on the stereochemistry of the core system was also investigated. All newly synthesized compounds were fully characterized by the usual spectroscopic and analytical methods. Keywords: hydroazulenes; liquid crystals

• ; nematic phases; smectic phases; Introduction Liquid crystals for display applications have to fulfill a complex, interdependent set of properties [1]. First of all, they must display a broad nematic phase, typically ranging from −30 °C to +80 °C. The absolute value for the dielectric anisotropy Δε should

• molecular design of new liquid crystals, electro-optical properties can now be predicted quite precisely based on molecular modeling [1][2]. However, full evaluation of the value of a new structure is still only possible after synthesis. In the past few years many attempts have been made to improve the

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

• differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction (WAXS). Keywords: cyanoacetates; 4-cyanobiphenyls; liquid crystals; malonates; nematic; Introduction Nematic liquid crystals display mesophases in which the molecules are oriented along one vector defined by the director

• axis, but with the molecular arrangement in random positional order [1]. Nematic phases typically display low viscosity [2][3][4]. Due to the long-range orientational order they reveal anisotropic properties. These features make nematic liquid crystals very attractive materials for electronics [5][6][7

• ][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

• background of liquid crystals is beyond the scope of this review, and the interested reader is directed to numerous texts on the subject [25][26][27][28][29]. The liquid-crystalline state is intermediate between that of a perfectly ordered crystal and a disordered isotropic liquid. The moieties within a

• presence of a solvent are known as lyotropic. A material that exhibits LC properties is referred to as a mesogen and is said to exhibit mesomorphism; although something that is mesogenic (e.g., proto-mesogens) is not necessarily mesomorphic. Thermotropic liquid crystals are usually formed by molecules that

• triphenylene discotic liquid crystals without disruption of the nature of the mesophase. Furthermore, thin films of Au@236,6 displayed 2-D hexagonal ordering on TEM grids, with interparticle distances less than twice the length of the organic moieties suggesting that the ligands at the surface were

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

Progress in liquid crystal chemistry II

• Sabine Laschat

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

• liquid crystals? Liquid crystals have a major impact on our modern society, reaching from simple digital calculators to high-resolution flat-panel displays, and their market volume is expected to further increase. For example, in 2010 revenues of €1,013 million from sales of liquid crystals were reported

• , the chemistry behind liquid crystals, and particularly the synthesis, is the platform for such tremendous technological achievements, and this is true for both calamitic (rod-like) as well as discotic (disk-shaped) or other types of liquid crystals [2][3][4]. Since our initial Thematic Series

• "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

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