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Search for "circular dichroism" in Full Text gives 130 result(s) in Beilstein Journal of Organic Chemistry.

Cycloheximide congeners produced by Streptomyces sp. SC0581 and photoinduced interconversion between (E)- and (Z)-2,3-dehydroanhydrocycloheximides

  • Li Yang,
  • Ping Wu,
  • Jinghua Xue,
  • Huitong Tan,
  • Zheng Zhang and
  • Xiaoyi Wei

Beilstein J. Org. Chem. 2017, 13, 1039–1049, doi:10.3762/bjoc.13.103

Graphical Abstract
  • conformers of both stereoisomers were subjected to TDDFT calculations of the electronic circular dichroism (ECD) spectra. As shown in Figure 3, the calculated ECD spectra of (4R,6R,αS)-1 and (4R,6R,αR)-1 were similar to one another and both in good agreement with the measured spectrum of 1, which indicated a
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Published 30 May 2017

Interactions between shape-persistent macromolecules as probed by AFM

  • Johanna Blass,
  • Jessica Brunke,
  • Franziska Emmerich,
  • Cédric Przybylski,
  • Vasil M. Garamus,
  • Artem Feoktystov,
  • Roland Bennewitz,
  • Gerhard Wenz and
  • Marcel Albrecht

Beilstein J. Org. Chem. 2017, 13, 938–951, doi:10.3762/bjoc.13.95

Graphical Abstract
  • formation, which might prevent the accessibility of the CD-moieties located on the polymer backbone, was avoided by the presence of pyridine as a non-polar solvent. Both NOESY NMR experiments and circular dichroism (results not shown) do not indicate any significant interaction of the CDs and the aromatic
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Published 18 May 2017

New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

  • Pavel Nagorny and
  • Zhankui Sun

Beilstein J. Org. Chem. 2016, 12, 2834–2848, doi:10.3762/bjoc.12.283

Graphical Abstract
  • close chiral anion-pair complexes would then undergo a chiral counterion-controlled asymmetric reaction with a nucleophile. This proposal was validated experimentally, and a chloride-induced conformational switch to form a helical backbone was experimentally observed by circular dichroism (CD) during
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Published 23 Dec 2016

Characterization of the synthetic cannabinoid MDMB-CHMCZCA

  • Carina Weber,
  • Stefan Pusch,
  • Dieter Schollmeyer,
  • Sascha Münster-Müller,
  • Michael Pütz and
  • Till Opatz

Beilstein J. Org. Chem. 2016, 12, 2808–2815, doi:10.3762/bjoc.12.279

Graphical Abstract
  • samples. For this purpose, we used analytical methods such as NMR, tandem mass spectrometry, vibrational and electronic circular dichroism spectroscopy (VCD and ECD), as well as chiral HPLC. Results and Discussion Pure MDMB-CHMCZCA (3) was obtained as a so-called “research chemical” (RC) from an online RC
  • ECD spectra were obtained on a J-815 circular dichroism spectropolarimeter (Jasco) in a 1 mm (path length) quartz glass cuvette and a spectral range of 400–185 nm. The measurements were carried out with an acetonitrile solution of MDMB-CHMCZCA (0.25 mmol/L), a scan speed of 20 nm/min and 8 repetitions
  • . The baseline was corrected by subtraction of a solvent spectrum recorded with the same parameters. Vibrational spectroscopy The infrared (IR) and vibrational circular dichroism (VCD) spectra were recorded with a Tensor 27 IR spectrometer (Bruker Optics) equipped with a PMA50 module for polarization
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Published 21 Dec 2016

Interactions between cyclodextrins and cellular components: Towards greener medical applications?

  • Loïc Leclercq

Beilstein J. Org. Chem. 2016, 12, 2644–2662, doi:10.3762/bjoc.12.261

Graphical Abstract
  • group of Yamamoto studied the effect of β-, γ-, G1-β-, and Me-α-CD on the thermal stability of an aqueous buffered solution of chicken egg white lysozyme by circular dichroism and fluorescence spectroscopy [91]. The thermal stability is significantly lowered in the presence of β-, γ-, and G1-β-CD
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Published 07 Dec 2016

Inhibition of peptide aggregation by means of enzymatic phosphorylation

  • Kristin Folmert,
  • Malgorzata Broncel,
  • Hans v. Berlepsch,
  • Christopher H. Ullrich,
  • Mary-Ann Siegert and
  • Beate Koksch

Beilstein J. Org. Chem. 2016, 12, 2462–2470, doi:10.3762/bjoc.12.240

Graphical Abstract
  • of phosphorylation, time-dependent CD (circular dichroism) measurements were performed. To ensure comparable and reproducible starting conditions, a disaggregation and concentration validation assay using HFIP (1,1,1,3,3,3-hexafluoropropan-2-ol) was performed. Thus, all aggregates that may have
  • solution was stored at −20 °C. Circular dichroism CD spectra were recorded by using a Jasco J-810 spectropolarimeter (Jasco, Gross-Umstadt, Germany) at 24 °C (Jasco PTC-348W1 peltier thermostat) using 0.2 mm path length Quartz Suprasil cuvettes (Hellma, Müllheim, Germany). After background correction, the
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Published 18 Nov 2016

Determination of the absolute stereostructure of a cyclic azobenzene from the crystal structure of the precursor containing a heavy element

  • Reji Thomas and
  • Nobuyuki Tamaoki

Beilstein J. Org. Chem. 2016, 12, 2211–2215, doi:10.3762/bjoc.12.212

Graphical Abstract
  • date there have been several spectroscopic, diffraction methods developed to determine the absolute stereostructure of chiral molecules [26][27][28][29][30][31][32][33][34][35]. The non-empirical methods employed to determine the absolute configuration of a molecule include circular dichroism, exciton
  • chirality methods [28][29], NMR spectroscopy [30][31][32], X-ray diffraction [33][34][35], etc. In addition to these methods, many researchers explored a combination of vibrational circular dichroism and quantum mechanical calculations to determine the absolute stereostructures [36][37][38]. Among various
  • known chirality to obtain the target molecule. We could determine the stereostructure of the cyclic azobenzene by comparing the HPLC data obtained with a chiral column and the circular dichroism (CD) spectra of the product obtained by reduction of the enantiopure precursor and the target molecule
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Published 19 Oct 2016

New furoisocoumarins and isocoumarins from the mangrove endophytic fungus Aspergillus sp. 085242

  • Ze’en Xiao,
  • Senhua Chen,
  • Runlin Cai,
  • Shao’e Lin,
  • Kui Hong and
  • Zhigang She

Beilstein J. Org. Chem. 2016, 12, 2077–2085, doi:10.3762/bjoc.12.196

Graphical Abstract
  • methyl protons H-4' and H-5' to C-2', and chelated hydroxy proton 8-OH to C-8, C-7, and C-8a (Figure 2). The negative circular dichroism at 265 nm (Figure 5) suggested R configuration at C-3, by comparison with data for isocoumarin derivatives described in the literature [13]. Thus, asperisocoumarin E (5
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Published 23 Sep 2016

Varioloid A, a new indolyl-6,10b-dihydro-5aH-[1]benzofuro[2,3-b]indole derivative from the marine alga-derived endophytic fungus Paecilomyces variotii EN-291

  • Peng Zhang,
  • Xiao-Ming Li,
  • Xin-Xin Mao,
  • Attila Mándi,
  • Tibor Kurtán and
  • Bin-Gui Wang

Beilstein J. Org. Chem. 2016, 12, 2012–2018, doi:10.3762/bjoc.12.188

Graphical Abstract
  • time-dependent density functional theory-electronic circular dichroism (TDDFT-ECD) calculations. A similar compound, whose planar structure was previously described but the relative and absolute configurations and 13C NMR data were not reported, was also identified and was tentatively named as
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Published 09 Sep 2016

From supramolecular chemistry to the nucleosome: studies in biomolecular recognition

  • Marcey L. Waters

Beilstein J. Org. Chem. 2016, 12, 1863–1869, doi:10.3762/bjoc.12.175

Graphical Abstract
  • attractive scaffold because a two-state approximation for folding was reasonable in most cases and the β-hairpin is far more amenable to NMR analysis than α-helices, which were usually characterized by Circular Dichroism (CD). Additionally, because the sidechains in β-hairpins interdigitate, they provide
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Published 17 Aug 2016

Artificial Diels–Alderase based on the transmembrane protein FhuA

  • Hassan Osseili,
  • Daniel F. Sauer,
  • Klaus Beckerle,
  • Marcus Arlt,
  • Tomoki Himiyama,
  • Tino Polen,
  • Akira Onoda,
  • Ulrich Schwaneberg,
  • Takashi Hayashi and
  • Jun Okuda

Beilstein J. Org. Chem. 2016, 12, 1314–1321, doi:10.3762/bjoc.12.124

Graphical Abstract
  • (polyethylene-polyethylene glycol), SDS (sodium dodecyl sulfate), TEV (Tobacco Etch Virus), MALDI–TOF–MS (matrix-assisted laser desorption/ionisation and time-of-flight mass spectrometry), FhuAΔCVFtev (FhuA Δ1-159_C545_V548_F501_tev), CD (circular dichroism), ESI-MS (electrospray ionization-mass spectrometry
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Published 24 Jun 2016

Three new trixane glycosides obtained from the leaves of Jungia sellowii Less. using centrifugal partition chromatography

  • Luíse Azevedo,
  • Larissa Faqueti,
  • Marina Kritsanida,
  • Antonia Efstathiou,
  • Despina Smirlis,
  • Gilberto C. Franchi Jr,
  • Grégory Genta-Jouve,
  • Sylvie Michel,
  • Louis P. Sandjo,
  • Raphaël Grougnet and
  • Maique W. Biavatti

Beilstein J. Org. Chem. 2016, 12, 674–683, doi:10.3762/bjoc.12.68

Graphical Abstract
  • Armen Instrument (Saint-Avé, France) fitted with a 1000 mL rotor containing 2016 twin-cells, equipped with a gradient pump and a 50 mL loop injection 6-way valve. Electronic circular dichroism (ECD) spectra were recorded in acetonitrile using a Jasco XLC 3195CD detector. Plant material The leaves of J
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Published 12 Apr 2016

Self and directed assembly: people and molecules

  • Tony D. James

Beilstein J. Org. Chem. 2016, 12, 391–405, doi:10.3762/bjoc.12.42

Graphical Abstract
  • electrochemistry [77]. The system has also been used with Eric Anslyn (University of Texas at Austin) to determine the ee of amines using circular dichroism (CD) spectroscopy [78]. The system was more recently used to measure the ee of amines using fluorescence [79]. The UK Office of Science and Innovation (OSI
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Published 01 Mar 2016

Interactions of cyclodextrins and their derivatives with toxic organophosphorus compounds

  • Sophie Letort,
  • Sébastien Balieu,
  • William Erb,
  • Géraldine Gouhier and
  • François Estour

Beilstein J. Org. Chem. 2016, 12, 204–228, doi:10.3762/bjoc.12.23

Graphical Abstract
  • CDs. The correlation between inclusion parameters and catalytic properties of CDs was studied by induced circular dichroism (ICD) of the inclusion complexes using rotational-strength analysis method. ICD analysis underlines a change of the environment in the cavity due to the formation of the
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Published 05 Feb 2016

Bifunctional phase-transfer catalysis in the asymmetric synthesis of biologically active isoindolinones

  • Antonia Di Mola,
  • Maximilian Tiffner,
  • Francesco Scorzelli,
  • Laura Palombi,
  • Rosanna Filosa,
  • Paolo De Caprariis,
  • Mario Waser and
  • Antonio Massa

Beilstein J. Org. Chem. 2015, 11, 2591–2599, doi:10.3762/bjoc.11.279

Graphical Abstract
  • to obtain both the enantiomers of chiral bioactive compounds. In this case, we focused on (R,R)-8a, which afforded the required (S)-7 (the absolute configuration has been previously determined by vibrational circular dichroism) [31]. Asymmetric synthesis of 9 by decarboxylation of (S)-7 Although
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Published 15 Dec 2015

Chiroptical properties of 1,3-diphenylallene-anchored tetrathiafulvalene and its polymer synthesis

  • Masashi Hasegawa,
  • Junta Endo,
  • Seiya Iwata,
  • Toshiaki Shimasaki and
  • Yasuhiro Mazaki

Beilstein J. Org. Chem. 2015, 11, 972–979, doi:10.3762/bjoc.11.109

Graphical Abstract
  • systems having strong chiroptical properties because they have great potential for use in optical devices involving polarized light [1][2][3]. Chiral response, in electronic circular dichroism (ECD) based on an exciton coupling between two adequate π-chromophores, can express a pronounced chiroptical
  • −341 (c 0.83 in CH2Cl2), respectively. Figure 2 depicted the electronic circular dichroism (ECD) spectra of the enantiomers of (+)/(−)-3 and (+)/(−)-9, and their UV–vis absorption spectra. The ECD spectrum of the (−)-9 enantiomer exhibited a clear bisignate CD curve with a negative peak at 274 nm and a
  • -IA3 column (20 Ø × 250 mm). The optical rotations were measured with JASCO P-1300 spectropolarimeter in 1 dm quartz cell at 24 °C. Electronic circular dichroism (ECD) spectra were recorded on JASCO J-725 spectrodichrometer. The spectra were combined after the baseline correction of each measurement
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Published 08 Jun 2015

Impact of multivalent charge presentation on peptide–nanoparticle aggregation

  • Daniel Schöne,
  • Boris Schade,
  • Christoph Böttcher and
  • Beate Koksch

Beilstein J. Org. Chem. 2015, 11, 792–803, doi:10.3762/bjoc.11.89

Graphical Abstract
  • included in this study by adding one, two, or three heptad repeats containing alanine in their f-positions (R2A3, R2A4 and R2A5); these were based on the sequence of R2A2 (Figure 1). Secondary and quaternary structure of the model peptides Circular dichroism (CD) spectroscopy and analytical
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Published 15 May 2015

TEMPO-derived spin labels linked to the nucleobases adenine and cytosine for probing local structural perturbations in DNA by EPR spectroscopy

  • Dnyaneshwar B. Gophane and
  • Snorri Th. Sigurdsson

Beilstein J. Org. Chem. 2015, 11, 219–227, doi:10.3762/bjoc.11.24

Graphical Abstract
  • in the melting temperature, while UA destabilized the duplex by more than 10 °C. Circular dichroism (CD) measurements indicated that all three labels were accommodated in B-DNA duplex. The mobility of the spin label TA varied with different base-pairing partners in duplex DNA, with the TA•T pair
  • gel electrophoresis. The incorporation of TA, UA and UC into DNA was confirmed by MALDI–TOF mass spectrometry (Table S1, Supporting Information File 1). Circular dichroism measurements showed that the incorporation of TA, UA and UC does not alter the B-DNA conformation of DNA duplexes containing these
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Published 09 Feb 2015

A comparative study of the interactions of cationic hetarenes with quadruplex-DNA forming oligonucleotide sequences of the insulin-linked polymorphic region (ILPR)

  • Darinka Dzubiel,
  • Heiko Ihmels,
  • Mohamed M. A. Mahmoud and
  • Laura Thomas

Beilstein J. Org. Chem. 2014, 10, 2963–2974, doi:10.3762/bjoc.10.314

Graphical Abstract
  • of 1 nm, a recording speed of 1 nm s−1 and a time per data point of 0.5 s. For the temperature dependent circular dichroism (CD) experiments, solutions of the ILPR-quadruplex a2 (20 μM) and the ligand (20 μM) were prepared in potassium phosphate buffer (95 mM, pH 7.0) and measured after an
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Published 11 Dec 2014

Trogopterins A–C: Three new neolignans from feces of Trogopterus xanthipes

  • Soyoon Baek,
  • Xuikui Xia,
  • Byung Sun Min,
  • Chanil Park and
  • Sang Hee Shim

Beilstein J. Org. Chem. 2014, 10, 2955–2962, doi:10.3762/bjoc.10.313

Graphical Abstract
  • comparing the circular dichroism (CD) data to those of previously reported neoligans containing a dihydrobenzofuran skeleton [17]. The CD of compound 1 showed positive cotton effects at 255 and 327 nm along with a negative cotton effect at 234 nm. These features were very similar to those of neolignans [17
  • with a Jasco P1000 digital polarimeter. UV spectra were recorded by a Hewlett Packard 8453 UV–vis spectrometer. CD spectra were obtained with a Jasco J-715 circular dichroism spectrophotometer. 1D and 2D NMR were performed on a VNS 600 MHz spectrometer operating at 600 MHz for protons and 150 MHz for
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Published 11 Dec 2014

Preparation of neuroprotective condensed 1,4-benzoxazepines by regio- and diastereoselective domino Knoevenagel–[1,5]-hydride shift cyclization reaction

  • László Tóth,
  • Yan Fu,
  • Hai Yan Zhang,
  • Attila Mándi,
  • Katalin E. Kövér,
  • Tünde-Zita Illyés,
  • Attila Kiss-Szikszai,
  • Balázs Balogh,
  • Tibor Kurtán,
  • Sándor Antus and
  • Péter Mátyus

Beilstein J. Org. Chem. 2014, 10, 2594–2602, doi:10.3762/bjoc.10.272

Graphical Abstract
  • performed on a Jasco HPLC system with Chiralpak IA column (5 μm, 150 × 4.6 mm, hexane/dichloromethane 80:20 or 70:30 eluents, 1 mL min−1 flow rate) and HPLC-ECD spectra were recorded in stopped-flow mode on a JASCO J-810 electronic circular dichroism spectropolarimeter equipped with a 10 mm HPLC flow cell
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Published 06 Nov 2014

Reversibly locked thionucleobase pairs in DNA to study base flipping enzymes

  • Christine Beuck and
  • Elmar Weinhold

Beilstein J. Org. Chem. 2014, 10, 2293–2306, doi:10.3762/bjoc.10.239

Graphical Abstract
  • 1I6S-Et-S4U2 and 1G6S-Et-S4U2 clearly confirms the shift of the thio-nucleobase absorption band over 300 nm towards lower wavelengths as it is typical for S-alkylated thio-nucleobases (Figure 2c and Figure 3c). Circular dichroism [53] spectroscopy is sensitive to the overall global conformation of
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Published 01 Oct 2014

Molecular recognition of AT-DNA sequences by the induced CD pattern of dibenzotetraaza[14]annulene (DBTAA)–adenine derivatives

  • Marijana Radić Stojković,
  • Marko Škugor,
  • Łukasz Dudek,
  • Jarosław Grolik,
  • Julita Eilmes and
  • Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2175–2185, doi:10.3762/bjoc.10.225

Graphical Abstract
  • recognition; circular dichroism; DBTAA-adenine conjugate; ds-DNA/RNA; minor groove binding; nucleic acids; Introduction The majority of natural and artificial applications involving small molecule-DNA/RNA recognition depend on several non-covalent binding modes. Typical examples are double-stranded (ds) DNA
  • due to the extensive broadening and decreasing of proton signals, which eventually merged with the baseline (details about unsuccessful NMR experiments see [11]). Circular dichroism (CD) experiments CD spectropolarimetry offers unique possibilities for the investigation of small molecule–DNA/RNA
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Published 12 Sep 2014

Multicomponent reactions in nucleoside chemistry

  • Mariola Koszytkowska-Stawińska and
  • Włodzimierz Buchowicz

Beilstein J. Org. Chem. 2014, 10, 1706–1732, doi:10.3762/bjoc.10.179

Graphical Abstract
  • %. The diastereoisomers were separated and their absolute configuration was determined using X-ray crystallography and circular dichroism spectroscopy. The stereochemical outcome of the synthesis of compounds 79 and 80 was suggested to result from some internal asymmetric induction of the chiral residue
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Published 29 Jul 2014

Clicked and long spaced galactosyl- and lactosylcalix[4]arenes: new multivalent galectin-3 ligands

  • Silvia Bernardi,
  • Paola Fezzardi,
  • Gabriele Rispoli,
  • Stefania E. Sestito,
  • Francesco Peri,
  • Francesco Sansone and
  • Alessandro Casnati

Beilstein J. Org. Chem. 2014, 10, 1672–1680, doi:10.3762/bjoc.10.175

Graphical Abstract
  • -tagged full-length Gal-3 was expressed in E. coli BL21 and purified on IMAC (immobilized metal ion affinity chromatography) columns. Purified protein was characterized by SDS-PAGE electrophoresis, circular dichroism (CD), and MS/MS analysis upon digestion on trypsin gel (see Figure S15, Supporting
  • /glycocalixarene binding experiments), 1H NMR spectra of selected intermediates, and final glycocalixarenes 1–4 together with electrophoresis gel, circular dichroism spectrum and thermal unfolding of purified Gal-3. Supporting Information File 610: Experimental part. Acknowledgements The authors gratefully
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Published 23 Jul 2014
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