Novel biphenyl-substituted 1,2,4-oxadiazole ferroelectric liquid crystals: synthesis and characterization

• Mahabaleshwara Subrao,
• Dakshina Murthy Potukuchi,
• Girish Sharada Ramachandra,
• Poornima Bhagavath,
• Sangeetha G. Bhat and
• Srinivasulu Maddasani

Beilstein J. Org. Chem. 2015, 11, 233–241, doi:10.3762/bjoc.11.26

• * phase. All the compounds in the 13b (C12.Ox.C*Cn) series are found to exhibit a similar sequence of phase transitions, i.e., Iso. – SmA – SmC* – Cryst. Hence, the LC phase variance exhibited by the 13a and 13b series is confirmed as SmA and SmA, SmC*, respectively. The phase transition studies of all

• – SmC* transition is of a weak first order or second order transition due to the changeover of the orthogonal to tilted phase structure with less tilt (about the normal). The minimal ∆H values noticed can be attributed to the second order phase transition in the 13b series. The thermograms obtained

• , (v) benzyl 2,2,2-trichloroacetimidate, CF3SO3H, n-hexane, rt, (vi) LiOH, MeOH, H2O, (vii) alkyl alcohol, DCC, DMAP, DCM, (viii) Pd/C, EtOAc, H2 (1 atm), (ix) 4-bromobenzoic acid, DCC, DMAP, DCM, (x) Pd(PPh3)2, Na2CO3, 1,2-DME, H2O, MW, 120 °C, 20 min. Phase transition temperatures (°C), enthalpy

Inclusion of trans-resveratrol in methylated cyclodextrins: synthesis and solid-state structures

• Lee Trollope,
• Dyanne L. Cruickshank,
• Terence Noonan,
• Susan A. Bourne,
• Milena Sorrenti,
• Laura Catenacci and
• Mino R. Caira

Beilstein J. Org. Chem. 2014, 10, 3136–3151, doi:10.3762/bjoc.10.331

• appears to undergo more than one phase transition. A second mass loss appears in the TG trace corresponding to partial guest loss and the DSC shows a sharp but small melting endotherm at ca. 233 °C, the remaining sample decomposing soon after, at ca. 320 °C. X-ray analysis Table 1 lists the crystal data

Cyclodextrin–polysaccharide-based, in situ-gelled system for ocular antifungal delivery

• Anxo Fernández-Ferreiro,
• Noelia Fernández Bargiela,
• María Santiago Varela,
• Maria Gil Martínez,
• Maria Pardo,
• Antonio Piñeiro Ces,
• José Blanco Méndez,
• Miguel González Barcia,
• Maria Jesus Lamas and
• Francisco.J. Otero-Espinar

Beilstein J. Org. Chem. 2014, 10, 2903–2911, doi:10.3762/bjoc.10.308

• situ-gelled vehicle and CDs containing high doses of fluconazole. An ophthalmic gel containing HPBCDs was demonstrated to be safe and bioadhesive. In the presence of simulated tear solution, the in situ-gelled vehicle was able to form a strong gel following the phase transition that allows controlled

Molecular ordering at electrified interfaces: Template and potential effects

• Thanh Hai Phan and
• Klaus Wandelt

Beilstein J. Org. Chem. 2014, 10, 2243–2254, doi:10.3762/bjoc.10.233

• adsorption and phase transition of 1,1’-dibenzyl-4,4’-bipyridinium molecules (abbreviated as DBV2+) on a chloride-modified Cu(111) electrode surface. The cyclic voltammogram (CV) of the Cu(111) electrode exposed to a mixture of 10 mM HCl and 0.1 mM DBVCl2 shows three distinguishable pairs of current waves P1

• so-called “herring-bone” structure. Upon lowering the electrode potential the first electron transfer step (at P1) causes a phase transition from the DBV2+-related herring-bone phase to the so-called "alternating stripe" pattern built up by the DBV+• species following a nucleation and growth

• /P1’ and P3/P3’) [5][6][7][13][14][15][16], as well as to an order/disorder phase transition due to chloride desorption/adsorption [17]. As mentioned in the Introduction, the viologen dication (DBV2+) is known to undergo two successive one-electron transfer steps in the electrochemical environment

The effect of permodified cyclodextrins encapsulation on the photophysical properties of a polyfluorene with randomly distributed electron-donor and rotaxane electron-acceptor units

• Aurica Farcas,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert,
• Flavian Farcas,
• Iuliana Stoica and
• Anton Airinei

Beilstein J. Org. Chem. 2014, 10, 2145–2156, doi:10.3762/bjoc.10.222

• DSC results suggest that the encapsulation of molecule 1 into TMS-β-CD and TMS-γ-CD cavities leads to more rigid copolymer structures with an increased Tg (Table 1). It should be pointed out that the higher molecular weight of 4a and 4b copolymers can also influence the phase transition temperature

Influence of cyclodextrin on the UCST- and LCST-behavior of poly(2-methacrylamido-caprolactam)-co-(N,N-dimethylacrylamide)

• Alexander Burkhart and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 1951–1958, doi:10.3762/bjoc.10.203

• complexation, the cloud point in the heating curves increases from 34 °C (6a) up to 47 °C (6aCD) with a sharp phase transition. Obviously, the complexation of the attached caprolactam ring with CD leads to a higher hydrophilicity of the copolymer and therefore to a better solubility in water. The postulated

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

• kind of a nematic phase, in agreement with the optical textures. Obviously, similar clusters as in the isotropic phase are observed in the nematic phase. No changes of the X-ray pattern indicating a phase transition could be detected on heating above or on cooling below 70 °C (see Figure S1 in

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

• isotropic phase. The extinction position lies along the layer normal, which coincides with the fan symmetry axis. By shearing the sample the planar texture could be transformed into a schlieren type. In the planar texture the SmAP–SmCAPA phase transition is accompanied with modification of the textural

• is accompanied with two current peaks per half cycle of applied voltage (Figure 6), that supports the antiferroelectric character of the SmCAPA phase. On further cooling the texture features in the planar cell slightly change at the SmCAPA–SmCG phase transition at T = 143 °C. Application of an

• electric field in the SmCG phase modifies the texture in such a way that one can speculate the transition from the SmCG phase to the SmCAPA phase takes place. At T = 138 °C another phase transition (SmCG–SmCSPA) is observed and the birefringence and character of the planar texture abruptly changes. In

End-group-functionalized poly(N,N-diethylacrylamide) via free-radical chain transfer polymerization: Influence of sulfur oxidation and cyclodextrin on self-organization and cloud points in water

• Sebastian Reinelt,
• Daniel Steinke and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 680–691, doi:10.3762/bjoc.10.61

• during the phase transition is initiated at the chain ends, where the mobility is highest [36]. For poly(N-isopropylacrylamide) (PNIPAM) previous studies demonstrated a broadened phase transition for polydisperse and low molecular weight samples [18][32][43]. Although the polymers (8a–d, 9a–d

Charge-transfer interaction mediated organogels from 18β-glycyrrhetinic acid appended pyrene

• Jun Hu,
• Jindan Wu,
• Qian Wang and
• Yong Ju

Beilstein J. Org. Chem. 2013, 9, 2877–2885, doi:10.3762/bjoc.9.324

• the control experiments. No gel formation was observed in these situations, and a red solution formed for 2 with 4, indicating the skeletons of both 3 and 4 are necessary. Thermochromic phase transition The CT gels based on GA-pyrene 3 and TNF 4 showed a thermochromic phase transition as all the other

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

• DSC traces are shown in Figure 3 and the phase transition data are summarized in Table 1. For the mesomorphism of the functionalized triphenylene monomers, compound 2 [52] and 3b [57] have been reported, 3a and 3c are new. They all display typical optical textures with homeotropic alignment behavior

• of the hexagonal columnar (Colh) mesophase (Figure 1). The monomers display different phase-transition temperatures related to the connecting functional group and the length of the chain. Compound 2 displayed a Col phase at room temperature with a clearing point of 111 °C (for the heating run), and

• did not crystallize even when cooled to −50 °C. Monomer 3a exhibited a narrow columnar mesophase range between 41 °C to 60 °C for heating, and between 59 °C to 11 °C for cooling. Comparing the phase-transition temperatures of 2 and 3a, it was found that the ester connecting group has the effect of

Self-assembly of 2,3-dihydroxycholestane steroids into supramolecular organogels as a soft template for the in-situ generation of silicate nanomaterials

• Valeria C. Edelsztein,
• Andrea S. Mac Cormack,
• Matías Ciarlantini and
• Pablo H. Di Chenna

Beilstein J. Org. Chem. 2013, 9, 1826–1836, doi:10.3762/bjoc.9.213

• trap the solvent molecules in the supramolecular network to form supramolecular gels. The non-covalent nature of these interactions makes it possible for the supramolecular gel systems to achieve a reversible sol–gel phase transition by the simple application of an external stimulus. Intrinsically

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

• director); (b) temperature-dependent layer spacing of compound 3b. Complementary guanidinium sulfonate 1 and guanidinium–sulfonimide ion pairs 2 and 3. Synthesis of the potassium sulfonimides 6a and 6b. Synthesis of guanidinium sulfonimides 2a,b, 3a,b and iodides 7∙I, 8∙I. Phase-transition temperatures (°C

The conjugation of nonsteroidal anti-inflammatory drugs (NSAID) to small peptides for generating multifunctional supramolecular nanofibers/hydrogels

• Jiayang Li,
• Yi Kuang,
• Junfeng Shi,
• Yuan Gao,
• Jie Zhou and
• Bing Xu

Beilstein J. Org. Chem. 2013, 9, 908–917, doi:10.3762/bjoc.9.104

• self-assembly in water. Transmission electron microscopy (TEM) In addition to the macroscopic phase transition such as hydrogelation, another hallmark of molecular self-assembly in water is the formation of ordered nanostructures (e.g., nanofibers or nanoparticles). As revealed by the TEM images

Thermotropic and lyotropic behaviour of new liquid-crystalline materials with different hydrophilic groups: synthesis and mesomorphic properties

• Alexej Bubnov,
• Miroslav Kašpar,
• Věra Hamplová,
• Ute Dawin and
• Frank Giesselmann

Beilstein J. Org. Chem. 2013, 9, 425–436, doi:10.3762/bjoc.9.45

• . Results and Discussion Thermotropic behaviour Mesomorphic properties For the studied materials, sequences of phases were determined by characteristic textures and their changes were observed in a polarizing optical microscope (POM). The phase-transition temperatures and transition enthalpies were

• obtained at 108 °C on free-standing films (FSF) (Figure 1b), and the N–SmC phase transition obtained at about 102 °C on FSF (Figure 1c). DSC plot on heating/cooling runs for indicated nonchiral TL1, TL3 and TL4 and for chiral TL2 and TL5 are presented in Figure 2 and Figure 3, respectively. The blue phase

• (BPII) and the cholesteric phase (N*) have been detected for the chiral TL2. The peak corresponding to the Iso-BPII phase transition has not been detected by DSC and the temperature of this phase transition has been taken from observations obtained by POM (Table 2). The type of the blue phase (BPII) has

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

• calorimetry (DSC). The thermodynamic data are presented in Table 1. A representative DSC trace obtained during the initial heating and cooling cycles scanned at a rate of 10 K min−1 for 1c is presented in Figure 2. The nematic–isotropic phase-transition enthalpies are of the order of 0.15~0.29 kJ/mol for 1a

• –1c and are in agreement with the reported enthalpies at the N–I phase transition exhibited by bent-core compounds. To gain an understanding of the structure–property relationship we synthesized other homologues of the same core with variations in the position of the chloro substituent, or without any

• temperature controller configured for HCS302 from INSTEC Inc. USA). The phase transition temperatures and associated enthalpies were recorded on differential scanning calorimetry (Perkin-Elmer Pyris-1 system) with a heating/cooling rate of 10 °C/min. 4-n-Butyloxy-2-hydroxybenzaldehyde (5a): In the synthesis

Design of a novel tryptophan-rich membrane-active antimicrobial peptide from the membrane-proximal region of the HIV glycoprotein, gp41

• Evan F. Haney,
• Leonard T. Nguyen,
• David J. Schibli and
• Hans J. Vogel

Beilstein J. Org. Chem. 2012, 8, 1172–1184, doi:10.3762/bjoc.8.130

• gp41w-FKA had very little effect on the phase transitions of DPPC lipids (Figure 5). The main phase transition of DPPC, seen at 41 °C, is unaffected by the addition of peptide, while the pretransition at ~34 °C is slightly broadened and shifts to a lower temperature. When gp41w-4R and gp41w-KA were

• . This large temperature shift compared to the main phase transition of DPPC indicates that the gp41w-4R peptide destabilizes zwitterionic bilayers more effectively than any of the other gp41w derivatives. For gp41w-KA, there are a number of peaks at temperatures below the phase-transition temperature of

• small peak at ~40 °C. The addition of gp41w-KA and gp41w-FKA to DPPG gave remarkably similar DSC results. The main phase transition at 40 °C is abolished in the presence of either peptide and is replaced by a broad transition centered at 47 °C. This could be due to the formation of peptide–lipid

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

• angle from a value of ca. 25° for x16 = 0.9 to ca. 10° for x16 = 0.7. Further addition of the short compound caused the tilt angle to vanish completely, which corresponds to a concentration-induced phase transition from the SmC to the SmA phase. Optical tilt angles are compared with the tilt angles

• other peaks. In Figure 11a the pseudohexagon is marked with white lines. Precise measurements of the smectic layer spacing d were obtained by small-angle X-ray scattering (SAXS). Figure 12a shows the smectic layer spacing d of the SmC and the SmF phases of PhP16. At the phase transition, we observe a

• clear step of the layer spacing from about 40 Å in the SmC phase to higher values of about 45 Å in the SmF phase, which suggests that the tilt angle is reduced at the phase transition. Accordingly, the optical tilt angle θ of PhP16 was measured (Figure 12b); the tilt angle in the SmF phase is ca. 27

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

• . In contrast to the core system presently used in most nematic LC materials, our new core based on perhydroazulenes showed [13], e.g., improved properties regarding phase-transition temperatures. Therefore, due to its potential use as a subsystem of many natural products, as well as as the core moiety

• established in the present case. Finally, we investigated compounds 9 and 10 under a polarizing microscope for their textural features, and DSC experiments were carried out to determine the phase-transition temperatures. In the case of 9, the first melting-point peak in the DSC never recovered, but a very

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

• -hexyl tail at the other, exhibit enantiotropic CybA–N phase sequences. Similar to the trimesogens CB-Ox-CB/n, a strong influence of spacer length and spacer parity on the phase-transition temperatures for these dimesogens is also observed. The shorter compound CB-Ox/3 with even-numbered spacer (O(CH2

• arranged in the cross section. On reduction of the temperature further, there is a significant change in the XRD pattern, indicating a phase transition. The diffuse scattering on the meridian becomes sharper and strongly rises in intensity (Figure 3c). In addition, a weak second-order reflection becomes

• proposed for the SmA-type clusters forming the NcybA phase (Figure 4a). This means that at this phase transition the molecular organization does not change fundamentally, but instead the short-range SmA-like clusters simply become fused to much larger clusters. The correlation length in this phase (T = 130

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

• (Scheme 5) were carefully purified and characterized through 1D and 2D NMR as well as through their other analytical data. Investigation of the mesogenic properties of the target compounds 8a, 8b, 10a and 10b Investigation of the materials synthesized above for their phase-transition behavior showed that

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

• -cyano-biphenyl moieties. Phase-transition temperatures [°C] and enthalpies [kJ/mol] of 11 and 13.a Supporting Information Supporting Information File 138: Full experimental procedures and DSC traces of 11b and 13b. Acknowledgements Generous financial support by the Bundesministerium für Bildung und

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

• the position on the central phenyl ring. The lowering of the smectic–isotropic phase-transition temperature by introduction of the lateral methyl group in the 6-position, OH 2b, amounts to 31 K. The influence of a methyl group in the obtuse angle of OH 2c, that is in position 2, can be virtually

• -crystalline behaviour was not observed for either of the nitro derivatives H 3c or OH 3c, probably because the 5-position of the nitro group, which is at the top of the bent molecules, is sterically unfavourable in most cases. Generally, melting temperatures and phase-transition temperatures of isophthalic

• influence of the pattern of substitution at the outer and/or the central phenyl ring on the phase-transition temperatures and phase type of the compounds OH 5 and OH 6 can be seen from Table 5. For comparison, corresponding compounds having the same aromatic core but without the hydroxy groups are given

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

• determined by measuring the UV–vis scattering spectrum of the empty cell. The liquid-crystal sample was filled into the cell in its isotropic phase by capillary action. The sample was heated up to a few degrees above the liquid-crystal to isotropic phase transition temperature and then was cooled into the