Synthesis of bis(3-{[2-(allyloxy)ethoxy]methyl}-2,4,6-trimethylbenzoyl)(phenyl)phosphine oxide – a tailor-made photoinitiator for dental adhesives

• Norbert Moszner,
• Iris Lamparth,
• Jörg Angermann,
• Urs Karl Fischer,
• Frank Zeuner,
• Thorsten Bock,
• Robert Liska and
• Volker Rheinberger

Beilstein J. Org. Chem. 2010, 6, No. 26, doi:10.3762/bjoc.6.26

• two highly efficient initiating radicals: a benzoyl and a phosphinoyl radical. CQ absorbs light in the region of 400–500 nm with a low absorption coefficient due to the n-π* transitions of the dicarbonyl group. Photo-DSC is a unique method for comparing the performance of different PIs. Therefore, the

• photopolymerization of a common dental dimethacrylate resin based on mixtures of Bis-GMA (42 wt %), UDMA (37 wt %), TEGDMA (21 wt %) and the PI WBAPO or BAPO (2.38 mmol/100 g resin) was studied by photo-DSC using a blue LED (emission spectrum: 380–515 nm, λmax = 460 nm) as irradiation source. The Photo-DSC plots

• (Figure 3) confirmed the same photoinitiating activity of the two PIs taking into consideration the experimental accuracy of the DSC method. Because of the excellent performance of the synthesized WBAPO, it has been used as part of the PI system in our current SEA AdheSE® One F. This self-etching enamel

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

• -benzyloxyphenol with butyryl chloride followed by removal of the protective benzyl group under reductive conditions as described in the literature [36] (Scheme 3). Mesogenic properties Transition temperatures and enthalpies of the newly prepared compounds were determined by differential scanning calorimetry (DSC

• the SmF phase in the latter. A DSC trace for 16D[6] is shown in Figure 3, and representative textures of its mesophases are presented in Figure 4. The tilted phases in both terphenyl compounds were identified by the appearance and subsequent characteristic changes of the Schlieren textures in the

• structurally similar mesogens containing the four ring systems A–D. Experimental Optical microscopy and phase identification were performed using a PZO “Biolar” polarized microscope equipped with a HCS400 Instec hot stage. Thermal analysis was obtained using a TA Instruments 2920 DSC. Transition temperatures

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

• purified and characterised by 1H, 13C NMR, mass spectrometry and elemental analysis (see experimental section). Thermotropic Properties The thermotropic behaviour of all materials was investigated by differential scanning calorimetry (DSC) and polarised optical microscopy (POM). The results are collected

• stage. DSC was performed using a Perkin Elmer Pyris 1. X-ray diffraction measurements were carried out on powder samples in glass capillaries of 1.5 mm diameter. The nematic phases were aligned in a magnetic field (1T) upon cooling from the isotropic to the nematic phase. The WAXS measurements were

N-alkyl-N-(phosphonoethyl) substituted (meth)acrylamides – new adhesive monomers for self-etching self-priming one part dental adhesive

• Joachim E. Klee and
• Uwe Lehmann

Beilstein J. Org. Chem. 2009, 5, No. 72, doi:10.3762/bjoc.5.72

• /141.2 ppm (3d), 121.7/140.2 ppm (3h). Absorptions of the P-OH moiety were found at 1078, 3390 and 3411 cm−1 (3c, 3d). DSC investigation of 3 The polymerization behavior of N-alkyl-N-(phosphonoethyl)acrylamides and methacrylamides 3 was investigated by photopolymerization using a DSC7/DPA7 unit. The

• spectrometer (Nicolet 6700 FT-IR spectrometer (Thermo Scientific). The 1H NMR, 13C NMR and 31P NMR spectra were obtained by employing Bruker AC 250 MHz equipment. The viscosities were measured with the help of a Bohlin-Rheometer CS-50 at 23 °C. The melting temperatures were measured by using a DSC 7 (Perkin

• -Elmer). The polymerization enthalpy was conducted in the isothermal mode at 37 °C, using the photo calorimeter DSC7/DPA7 (Perkin-Elmer). The light intensity in the visible portion of the spectrum was 108 mW·cm−2. Each DSC experiment included a short dark period (typically 6 s) and the subsequent

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

• opposite signs of E. A Netzsch DSC-204 Phoenix instrument was used for differential scanning calorimetry analyses at a scan rate of 5 K min−1. Structure of different liquid crystalline phases build with two kinds of hard spherocylinders with strongly differing lengths. Molecular structure of the mesogens

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

• nucleophilic substitution. The mesomorphic behaviour of these compounds was investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and X-ray diffraction (WAXS and SAXS) and revealed smectic A mesophases for bromides, chlorides and azides 3, 4 and 6. For these compounds a

• calorimetry (DSC), polarizing optical microscopy (POM) and X-ray diffraction (WAXS and SAXS). The DSC results for bromides 3 are summarized in Table 1. Whereas compounds 3a,c,e with even chain lengths of the spacer displayed monotropic SmA phases, compounds 3b,d with odd chain lengths displayed enantiotropic

• SmA phases. A typical DSC curve of derivative 3d with a pentyloxy spacer is shown in Figure 1. On the third heating a melting transition at 40 °C into the SmA phase and a clearing transition at 57 °C could be observed. Subsequent cooling revealed an isotropic to SmA transition at 60 °C and 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

• ][25][26][27][28][29][30]. Their characterization was the result of the combination and interpretation of thermal studies (Thermogravimetry Analysis or TGA, Differential Scanning Calorimetry or DSC), direct polarized optical microscopy (POM) observation and small angle X-ray diffraction studies (SAXS

• DSC results are obtained from the second thermic cycle (2nd heating and cooling) and all phase transitions described occurred in the ionic liquids between −80 °C to 200 °C (ESI). The DSC graphs for the compounds with short aliphatic chains exhibit a glass transition during the cooling process rather

• (DSC, X-Ray, dilatometry). Acknowledgments This work was supported by the Institute for Physics and Chemistry of Materials Strasbourg, and University of Strasbourg.

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

• calorimetry (DSC) investigations only the transitions of the liquid crystal are found up to about 100 °C, where decomposition of the PVP sheath starts to take place. When fully dried the fibres also show good mechanical stability so that they can be pulled from the glass slide and folded or rolled together

• described at the end of the previous paragraph. But at least for the two highest flow rates the LC core visible in the non-POM photographs is as thick as the whole fibres in the first samples (see for Figure 3d1 and Figure 3e1). DSC thermograms of these fibres are presented in Figure 5, as well as the

• and in a subsequent second heating experiment only the N-iso. transition was found and it was shifted towards lower temperatures. This change in the effective phase sequence could be verified by textural observations during a similar experiment in the microscope. When repeating the DSC heating scan

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

• .5.57 Abstract Tetraphenylenes 2 with eight peripheral gallic esters were prepared in two steps from octamethoxytetraphenylene 1 in 19–72% yield. Investigation of the mesomorphic properties of 2 by DSC, POM and X-ray diffraction revealed that derivatives 2a–d with short alkoxy chain lengths (C5–C8) did

• purification the desired gallic ester-substituted tetraphenylenes 2a–l in 19–72%. In some cases purification turned out to be rather tedious resulting in decreased yields. Mesomorphic properties of compounds 2 were studied by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and X

• -ray diffraction (WAXS, SAXS). The DSC results are summarized in Table 1. While compounds 2a–d with chain lengths up to C8 showed only crystal to crystal transitions and isotropic melting, tetraphenylenes 2e–l with chain lengths between C9 and C16 displayed enantiotropic mesomorphism. For compounds 2e

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

• general stability order to be I−< BF4− ≈ PF6−< CF3SO3−< (CF3SO2)2N− (Figure 4). For all the compounds, the mesomorphic behaviour and phase transition temperatures were investigated by polarized optical microscopy (POM), differential scanning calorimetry (DSC), and powder X-ray diffractometry (XRD). To

• avoid possible effects of hydration of the materials, all were dried in vacuo before X-ray and DSC analyses. The phase transition temperatures and the corresponding enthalpy changes derived for compounds 1a–e are compiled in Table 2, while typical results are displayed in Figure 5. The high stability of

• 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

Synthesis of mesogenic phthalocyanine-C₆₀ donor–acceptor dyads designed for molecular heterojunction photovoltaic devices

• Yves Henri Geerts,
• Olivier Debever,
• Claire Amato and
• Sergey Sergeyev

Beilstein J. Org. Chem. 2009, 5, No. 49, doi:10.3762/bjoc.5.49

• ) mesophases. Upon heating, transitions to isotropic liquid were observed at 120 °C and 90 °C for 2c and 2d, respectively. For 2c this transition was only detectable by POM and not by differential scanning calorimetry (DSC), while for 2d DSC on heating revealed an endothermic peak at 90 °C [enthalpy 2.7 kJ/mol

• was controlled by a Linkam Scientific Instruments GS350 hot stage. For DSC, a Perkin Elmer Diamond DSC calorimeter was used. Electrochemistry. Cyclic voltammetry experiments were performed with a computer controlled Autolab potentiostat. Measurements were carried out at room temperature in a three

Pd/C- Mediated synthesis of indoles in water

• Mohosin Layek,
• Udaya Lakshmi,
• Dipak Kalita,
• Deepak K. Barange,
• Aminul Islam,
• K. Mukkanti and
• Manojit Pal

Beilstein J. Org. Chem. 2009, 5, No. 46, doi:10.3762/bjoc.5.46

• ) are given in hertz. Infrared spectra were recorded on a FTIR spectrometer. Melting points were determined by using thermal analysis and differential scanning calorimetry (DSC) was generated with the help of DSC-60A dector. MS spectra were obtained on a mass spectrometer. Chromatographic (HPLC) purity

Shape- persistent macrocycle with intraannular alkyl groups: some structural limits of discotic liquid crystals with an inverted structure

• Sigurd Höger,
• Jill Weber,
• Andreas Leppert and
• Volker Enkelmann

Beilstein J. Org. Chem. 2008, 4, No. 1, doi:10.1186/1860-5397-4-1

• observed by DSC. A recrystallization of the material during the cooling process could also not be observed, either by polarizing microscopy or by DSC measurements (for the aggregation of 26b in solution see Supporting Information File 1). These data show that the adaptable substituents are another