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

• in X-ray measurements. Experimental Measurements All compounds were studied using differential scanning calorimetry (DSC). The materials of 2–5 mg were hermetically closed in the aluminium pans and placed in nitrogen atmosphere of a Perkin–Elmer Pyris Diamond calorimeter. Cooling and heating rates of

Total synthesis and cytotoxicity of the marine natural product malevamide D and a photoreactive analog

• Werner Telle,
• Gerhard Kelter,
• Heinz-Herbert Fiebig,
• Peter G. Jones and
• Thomas Lindel

Beilstein J. Org. Chem. 2014, 10, 316–322, doi:10.3762/bjoc.10.29

• ) and acidic deprotection afforded diazirine diol 25. Figure 2 shows the DSC (differential scanning calorimetry) profile of 25, which melts at 54 °C and starts to decompose above 80 °C, indicating sufficient thermal stability for biological studies. Monosilylation of the primary hydroxy group of 25

The difluoromethylene (CF₂) group in aliphatic chains: Synthesis and conformational preference of palmitic acids and nonadecane containing CF₂ groups

• Yi Wang,
• Ricardo Callejo,
• Alexandra M. Z. Slawin and
• David O’Hagan

Beilstein J. Org. Chem. 2014, 10, 18–25, doi:10.3762/bjoc.10.4

• palmitic acids are characterized by differential scanning calorimetry (DSC) to determine melting points and phase behaviour relative to palmitic acid (62.5 °C). It emerges that 6c, with the CF2 groups placed 1,4- to each other, has a significantly higher melting point (89.9 °C) when compared to the other

• bond proved efficient and the resultant tetrafluoropentadecabenzene 26 was readily oxidized to palmitic acid 6c as illustrated in Scheme 2. This completed the syntheses of the palmitic acid analogues 6a–c. Differential scanning calorimetry (DSC) data was then measured for all three of the palmitic acid

Synthesis, characterization and initial evaluation of 5-nitro-1-(trifluoromethyl)-3H-1λ³,2-benziodaoxol-3-one

• Nico Santschi,
• Roman C. Sarott,
• Elisabeth Otth,
• Reinhard Kissner and
• Antonio Togni

Beilstein J. Org. Chem. 2014, 10, 1–6, doi:10.3762/bjoc.10.1

• kinetic studies showed that this new derivative is almost one order of magnitude more reactive. Furthermore, differential scanning calorimetry measurements indicated that, in addition, it is also safer to handle. Keywords: cyclic voltammetry; differential scanning calorimetry; electrophilic

• of the I–CF3 bond should display a higher activation barrier. Recently, differential scanning calorimetry (DSC) measurements for reagent 2 and its precursors were published indicating a decomposition energy of 159 kJ/mol (502 J/g) for 2 [17]. Furthermore, a Koenen test suggested explosiveness

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

• with 10 mol % of Co2(CO)8 as the catalyst in refluxing 1,4-dioxane. The liquid crystalline properties were investigated by using polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Trimer 4 with an ester connecting group and a longer spacer

• oligomers. Mesomorphism POM and DSC Initially, we studied the mesomorphic properties of the monomers and trimers by using polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The POM results of the monomers and trimers are summarized in Figure 1 and Figure 2, respectively. The

Oligomeric epoxide–amine adducts based on 2-amino-N-isopropylacetamide and α-amino-ε-caprolactam: Solubility in presence of cyclodextrin and curing properties

• Julian Fischer and
• Helmut Ritter

Beilstein J. Org. Chem. 2013, 9, 2803–2811, doi:10.3762/bjoc.9.315

• mixtures were analyzed by oscillatory rheology and differential scanning calorimetry, whereby significant differences in setting time, viscosity, and stiffness were observed. Keywords: amino acids; curing properties; cyclodextrin; epoxide–amine oligomers; LCST; Introduction Many partially hydrophobic

Crystal design using multipolar electrostatic interactions: A concept study for organic electronics

• Peer Kirsch,
• Qiong Tong and
• Harald Untenecker

Beilstein J. Org. Chem. 2013, 9, 2367–2373, doi:10.3762/bjoc.9.272

• system equipped with a 7000A Triple Quad detector. Melting points were determined by differential scanning calorimetry (DSC) performed on a Universal V4.5A (TA Instruments) at a heating/cooling rate of 20 K∙min−1. The temperature was calibrated with indium. The measurements were performed under a

Polymeric redox-responsive delivery systems bearing ammonium salts cross-linked via disulfides

• Christian Dollendorf,
• Martin Hetzer and
• Helmut Ritter

Beilstein J. Org. Chem. 2013, 9, 1652–1662, doi:10.3762/bjoc.9.189

• determined using differential scanning calorimetry (DSC). As a reference poly(DEAAm-co-DMAEMA, 1:1) (3) with a Tg of 43 °C was used. Cross-linking with CL 2 slightly increases the Tg from 43 to 47 and 49 °C for 5a, 5b and 5c, respectively. In contrast, samples containing CL 1 showed a stronger influence of

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

• % yield, respectively. In comparison the guanidinium iodide 7∙I was obtained in 94% yield by heating 7∙Cl with KI in MeCN under reflux (Scheme 3). The mesomorphic properties of ion pairs 2,3 and guanidinium halides 7∙I, 7∙Cl, 8∙I were studied by differential scanning calorimetry (DSC) and polarizing

• spectrometer. Polarizing optical microscopy: Olympus BX50 polarizing microscope combined with a Linkam TP93 central controller. MS (ESI): Bruker Daltonics microTOF-Q spectrometer. Differential scanning calorimetry (DSC): Mettler-Toledo DSC 822e (heating/cooling rates were 10 K min−1). X-ray diffraction (WAXS

1-n-Butyl-3-methylimidazolium-2-carboxylate: a versatile precatalyst for the ring-opening polymerization of ε-caprolactone and rac-lactide under solvent-free conditions

• Astrid Hoppe,
• Faten Sadaka,
• Claire-Hélène Brachais,
• Gilles Boni,
• Jean-Pierre Couvercelle and
• Laurent Plasseraud

Beilstein J. Org. Chem. 2013, 9, 647–654, doi:10.3762/bjoc.9.73

• pentaerythritol as initiator alcohols, and the products were fully characterized by 1H and 13C{1H} NMR spectroscopy, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). BMIM-2-CO2 acts as an N-heterocyclic carbene precursor, resulting from in situ decarboxylation, either by heating

• spectroscopy, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). Polymerization data are summarized in Table 1 and Table 2. As shown in Table 1 and Table 2, full conversion is observed for all ROPs of ε-caprolactone initiated by the various alcohols while conversions in the range

• differential scanning calorimetry is summarized in Table 4. DSC profiles are depicted in Supporting Information File 2 (Figure S1). Samples with molecular weight in the 1100–1500 Da range (Table 4), show similar Tm and Tc, although the endings of the chains are different. However, values for the crystallinity

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

• behaviour. Such materials are of high potential interest for challenging issues such as the self-organization of carbon nanotubes or various nanoparticles. Thermotropic mesomorphic properties have been studied by using polarizing optical microscopy, differential scanning calorimetry and X-ray scattering

• evaluated from differential scanning calorimetry (DSC) measurements. Thermotropic liquid-crystalline properties of all compounds under study are summarized in Table 2. On cooling from the isotropic state, TL1 and TL4, with quite a different structure of the molecular core and aliphatic chains (see Table 1

• stabilisation within ±0.1 K. Phase-transition temperatures and enthalpies were determined by differential scanning calorimetry (DSC - Pyris Diamond Perkin-Elmer 7) on samples of 3–6 mg hermetically sealed in aluminium pans in cooling/heating runs in a nitrogen atmosphere at a heating/cooling rate of 5 K min−1

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

• characterization is consistent with data from elemental and spectroscopic analysis. The materials thermal behaviour and phase characterization have been investigated by differential scanning calorimetry and polarizing microscopy. All the compounds exhibit a wide-ranging monotropic nematic phase. Keywords: bent

• is more stable towards hydrolysis due to intramolecular hydrogen bonding. We report here the synthesis and characterization of the compounds 1a–1f (Scheme 1) by elemental analysis, spectroscopic data, polarized optical microscopy (POM) and differential scanning calorimetry (DSC). Results and

• 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

Polysiloxane ionic liquids as good solvents for β-cyclodextrin-polydimethylsiloxane polyrotaxane structures

• Narcisa Marangoci,
• Rodinel Ardeleanu,
• Laura Ursu,
• Constanta Ibanescu,
• Maricel Danu,
• Mariana Pinteala and
• Bogdan C. Simionescu

Beilstein J. Org. Chem. 2012, 8, 1610–1618, doi:10.3762/bjoc.8.184

• deformation. Various rheological parameters were calculated by using the Rheoplus software. Differential scanning calorimetry (DSC) DSC measurements were conducted on a DSC 200 F3 Maia device (Netzsch, Germany). About 10 mg of each sample was heated in pressed and pierced aluminum crucibles. A heating rate of

Influence of cyclodextrin on the solubility of a classically prepared 2-vinylcyclopropane macromonomer in aqueous solution

• Helmut Ritter,
• Jia Cheng and
• Monir Tabatabai

Beilstein J. Org. Chem. 2012, 8, 1528–1535, doi:10.3762/bjoc.8.173

• differential scanning calorimetry (DSC) with a Perkin-Elmer Model DSC-7 in nitrogen atmosphere; about 10 mg samples were used at a scan rate of 15 K/min. Tg was taken as the average of three measurements using the midpoint method. LCST were determined by transmission changes (at 500 nm) of the solutions heated

Synthesis and characterization of low-molecular-weight π-conjugated polymers covered by persilylated β-cyclodextrin

• Aurica Farcas,
• Ana-Maria Resmerita,
• Andreea Stefanache,
• Mihaela Balan and
• Valeria Harabagiu

Beilstein J. Org. Chem. 2012, 8, 1505–1514, doi:10.3762/bjoc.8.170

• taken into consideration. The thermal stability of the inclusion-complex BTc, PDOF-BT and the PDOF-BTc copolymers was investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), as shown in Figure 5 and Figure 6, and the results are summarized in Table 2. The

• . The molecular weights of copolymers were determined by gel permeation chromatography (GPC) in CH2Cl2 by using a Water Associates 440 instrument and polystyrene calibrating standards. Differential scanning calorimetry (DSC) was performed with a Mettler Toledo DSC-12E calorimeter with two repeated

The preferred conformation of erythro- and threo-1,2-difluorocyclododecanes

• Yi Wang,
• Peer Kirsch,
• Tomas Lebl,
• Alexandra M. Z. Slawin and
• David O'Hagan

Beilstein J. Org. Chem. 2012, 8, 1271–1278, doi:10.3762/bjoc.8.143

• 5b. The C–CHF–C angle (115.62°) is the largest; however some C–CH2–C angles are clearly strained at ~115.0°. Supporting Information The Supporting Information contains NMR spectra and results of the differential scanning calorimetry, variable-temperature NMR, and computational studies. Supporting

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

• not disrupt bilayer organization in neutral liposomes to the same extent as gp41w or gp41w-4R (Figure 4C). Differential scanning calorimetry The gp41w derivatives were added to 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dipalmitoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DPPG) lipid

• suspensions and the resulting lipid and peptide mixtures were examined by differential scanning calorimetry (DSC) to determine the effect of the peptides on the thermotropic phase behaviour of phospholipids. Eukaryotic membranes typically have a high phosphatidylcholine content, while bacterial membranes are

• component of bee venom and a known lytic peptide, was used as a positive control. Calcein leakage was measured for LUVs made from lipid mixtures of ePC:ePG, ePE:ePG or ePC:ePE. Differential scanning calorimetry Lipid films of 0.5 mg pure DPPC or DPPG were prepared as described above and stored at −20 °C

Synthesis and characterization of a novel carboxyl group containing (co)polyimide with sulfur in the polymer backbone

• Miroslav Mrsevic,
• David Düsselberg and
• Claudia Staudt

Beilstein J. Org. Chem. 2012, 8, 776–786, doi:10.3762/bjoc.8.88

• during the polyaddition reaction. DSC measurements Differential scanning calorimetry (DSC) is a method to characterize the thermal properties of polymers and is also useful in disclosing composition based correlations. In order to do so, the glass-transition temperatures of all (co)polyimides synthesized

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

• studied by optical polarizing microscopy (PM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). All dimesogens exhibit broad ranges of cybotactic nematic phases (NcybA and NcybC), in some cases accompanied by additional mesophases (CybA or SmC) at lower temperature. The combination of

• differential scanning calorimetry (DSC, DSC-7, Perkin-Elmer). The assignment of the mesophases is based on the combined results of optical textures and X-ray diffraction (XRD) studies. XRD investigations on aligned samples were performed by using a 2D wire detector (HI-Star, Siemens AG). Alignment was achieved

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

• several liquid-crystalline phases over a wide temperature range. Variable-temperature optical polarized microscopy (vt-OPM) and differential scanning calorimetry (DSC) measurements revealed that compound 8b is converted into a SmC phase at ~28 °C and converts into a short-temperature-range SmA and N phase

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

• ,b were isolated as colourless solids in 59% and 41% yield. The obtained malonate and cyanoacetic esters 11a,b and 13a,b were subjected to differential scanning calorimetry (DSC) studies (Figure 1, Figure 2, and Table 1). During the first heating runs all compounds did not show the appearance of any

• referenced to an internal Me4Si (TMS) standard. IR: Bruker 22 FT-IR spectrometer with a golden-gate single-reflection diamond ATR system. MS: Bruker Daltonics mikro-TOF-Q (ESIMS). Differential scanning calorimetry (DSC): Mettler-Toledo DSC 822e (heating/cooling rates were 5 or 10 K·min−1). Polarizing optical

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

• by differential scanning calorimetry, polarising microscopy, X-ray diffraction and dielectric and electro-optical measurements. The paper reports on new findings with respect to the structure–property relationships of bent-core mesogens. On one hand, the disruptive effect of laterally substituted

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

• obtained by this route is 22 ± 5% (based on the fourteen known examples) [29][30][31][32]. Phase behaviour of the phthalocyanines determined by differential scanning calorimetry (second heating and first cooling cycle and a heating/cooling rate of 10 °C min−1). Supporting Information Synthesis, analytical

Novel carbazole–pyridine copolymers by an economical method: synthesis, spectroscopic and thermochemical studies

• Aamer Saeed,
• Madiha Irfan and
• Shahid Ameen Samra

Beilstein J. Org. Chem. 2011, 7, 638–647, doi:10.3762/bjoc.7.75

• of P2a in THF at room temperature. Thermochemical properties of the polymers The thermal properties of the two series of polymers, P1 and P2 were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). For TGA the samples were heated (PerkinElmer Thermal Analysis

• (ADLAS DPY 425II, output power ≈ 400 mW at λ = 532 nm) as the light source. Thermogravimetric analysis (TGA) was performed with a PerkinElmer Thermal analysis System 409. Differential scanning calorimetry (DSC) measurements were performed using Bruker Reflex II thermosystem. The TGA and DSC measurements