@article{AndrewsRossMunzkeetal.2016, author = {Andrews, Nicholas L. P. and Ross, Rachel and Munzke, Dorit and van Hoorn, Camiel and Brzezinski, Andrew and Barnes, Jack A. and Reich, Oliver and Loock, Hans-Peter}, title = {In-fiber Mach-Zehnder interferometer for gas refractive index measurements based on a hollow-core photonic crystal fiber}, series = {Optics express : the international electronic journal of optics}, volume = {24}, journal = {Optics express : the international electronic journal of optics}, publisher = {Optical Society of America}, address = {Washington}, issn = {1094-4087}, doi = {10.1364/OE.24.014086}, pages = {14086 -- 14099}, year = {2016}, abstract = {We describe an in-fiber interferometer based on a gas-filled hollow-core photonic crystal fiber. Expressions for the sensitivity, figure of merit and refractive index resolution are derived, and values are experimentally measured and theoretically validated using mode field calculations. The refractive indices of nine monoatomic and molecular gases are measured with a resolution of delta(ns) < 10(-6). (C)2016 Optical Society of America}, language = {en} } @phdthesis{Audoersch2016, author = {Aud{\"o}rsch, Stephan}, title = {Die Synthese von (2Z,4E)-Diencarbons{\"a}ureestern und ihre Anwendung in der Totalsynthese von Polyacetylenen}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-92366}, school = {Universit{\"a}t Potsdam}, pages = {139}, year = {2016}, abstract = {Z,E-Diene sind ein h{\"a}ufig auftretendes Strukturmerkmal in Naturstoffen. Aus diesem Grund ist die einfache Darstellung dieser Struktureinheit von großen Interesse in der organischen Chemie. Das erste Ziel der vorliegenden Arbeit war daher die Weiterentwicklung der Ringschlussmetathese-/ baseninduzierten Ring{\"o}ffnungs-/ Veresterungssequenz (RBRV-Sequenz) zur Synthese von (2Z,4E)-Diencarbons{\"a}ureethylestern ausgehend von Butenoaten. Dazu wurde zun{\"a}chst die RBRV-Sequenz optimiert. Diese aus drei Schritten bestehende Sequenz konnte in einem Eintopf-Verfahren angewendet werden. Die Ringschlussmetathese gelang mit einer Katalysatorbeladung von 1 mol\% des GRUBBS-Katalysators der zweiten Generation in Dichlormethan. F{\"u}r die baseninduzierte Ring{\"o}ffnung des β,γ-unges{\"a}ttigten δ Valerolactons wurde NaHMDS verwendet. Die Alkylierung der Carboxylatspezies gelang mit dem MEERWEIN-Reagenz. Die Anwendbarkeit der Sequenz wurde f{\"u}r verschiedene Substrate demonstriert. Die Erweiterung der Methode auf α-substituierte Butenoate unterlag starken Einschr{\"a}nkungen. So konnte der Zugang f{\"u}r α Hydroxyderivate realisiert werden. Bei der Anwendung der RBRV-Sequenz auf die α-substituierten Butenoate wurde festgestellt, dass diese sich nur in moderaten Ausbeuten umsetzen ließen und zudem nicht selektiv zu den (2E,4E)-konfigurierten α-substituierten-Dienestern reagierten. Der Einsatz von Eninen unter den Standardbedingungen der RBRV-Sequenz gelang nicht. Erst nach Modifizierung der Sequenz (h{\"o}here Katalysatorbeladung, Wechsel des L{\"o}sungsmittels) konnten die [3]Dendralen-Produkte in geringen Ausbeuten erhalten werden. Im zweiten Teil der Arbeit wurde der Einsatz von (2Z,4E)-Diencarbons{\"a}ureethylestern in der Totalsynthese von Naturstoffen untersucht. Dazu wurden zun{\"a}chst die Transformationsm{\"o}glichkeiten der Ester gepr{\"u}ft. Es konnte gezeigt werden, dass sich (2Z,4E)-Diencarbons{\"a}ureethylester insbesondere zur Synthese von (2Z,4E)-Aldehyden sowie zum Aufbau der (3Z,5E)-Dien-1-in-Struktur eignen. Anhand dieser Ergebnisse wurde im Anschluss die RBRV-Sequenz in der Totalsynthese eingesetzt. Dazu wurde zun{\"a}chst der (2Z,4E)-Dienester Microsphaerodiolin in seiner ersten Totalsynthese auf drei verschiedene Routen hergestellt. Im Anschluss wurden sechs verschiedene Polyacetylene mit einer (3Z,5E)-Dien-1-in-Einheit hergestellt. Schl{\"u}sselschritte in ihrer Synthese waren immer die RBRV-Sequenz zum Aufbau der Z,E-Dien-Einheit, die Transformation des Esters in ein terminales Alkin sowie die CADIOT-CHODKIEWICZ-Kupplung zum Aufbau unsymmetrischer Polyine. Alle sechs Polyacetylene wurden zum ersten Mal in einer Totalsynthese synthetisiert. Drei Polyacetylene wurden ausgehend von (S)-Butantriol enantiomerenrein dargestellt. Anhand ihrer Drehwerte konnte eine Revision der von YAO und Mitarbeitern vorgenommen Zuordnung der Absolutkonfiguration der Naturstoffe vorgenommen werden.}, language = {de} } @article{BaderKlierHettrichetal.2016, author = {Bader, Denise and Klier, Dennis Tobias and Hettrich, C. and Bier, Frank Fabian and Wessig, Pablo}, title = {Detecting carbohydrate-lectin interactions using a fluorescent probe based on DBD dyes}, series = {Analytical methods : advancing methods and applications}, volume = {8}, journal = {Analytical methods : advancing methods and applications}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1759-9660}, doi = {10.1039/c5ay02991k}, pages = {1235 -- 1238}, year = {2016}, abstract = {Herein we present an efficient synthesis of a biomimetic probe with modular construction that can be specifically bound by the mannose binding FimH protein - a surface adhesion protein of E. coli bacteria. The synthesis combines the new and interesting DBD dye with the carbohydrate ligand mannose via a Click reaction. We demonstrate the binding to E. coli bacteria over a large concentration range and also present some special characteristics of those molecules that are of particular interest for the application as a biosensor. In particular, the mix-and-measure ability and the very good photo-stability should be highlighted here.}, language = {en} } @article{BaierKellingSchildeetal.2016, author = {Baier, Heiko and Kelling, Alexandra and Schilde, Uwe and Holdt, Hans-J{\"u}rgen}, title = {Investigation of the Catalytic Activity of a 2-Phenylidenepyridine Palladium(II) Complex Bearing 4,5-Dicyano-1,3-bis(mesityl)imidazol-2-ylidene in the Mizoroki-Heck Reaction}, series = {Zeitschrift f{\~A}¼r anorganische und allgemeine Chemie}, volume = {642}, journal = {Zeitschrift f{\~A}¼r anorganische und allgemeine Chemie}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0044-2313}, doi = {10.1002/zaac.201500625}, pages = {140 -- 147}, year = {2016}, abstract = {The phenylidenepyridine (ppy) palladacycles [PdCl(ppy)(IMes)] (4) [IMes = 1,3-bis(mesityl) imidazol-2-ylidene] and [PdCl(ppy){(CN)(2)IMes}] (6) [(CN)(2)IMes = 4,5-dicyano-1,3-bis(mesityl) imidazol-2-ylidene] were prepared by facile two step syntheses, starting with the reaction of palladium(II) chloride with 2-phenylpyridine followed by subsequent addition of the NHC ligand to the precatalyst precursor [PdCl(ppy)](2). Suitable crystals for the X-ray analysis of the complexes 4 and 6 were obtained. It was shown that 6 has a shorter NHC-palladium bond than the IMes complex 4. The difference of the palladium carbene bond lengths based on the higher pi-acceptor strength of (CN)(2)IMes in comparison to IMes. Thus, (CN)(2)IMes should stabilize the catalytically active central palladium atom better than IMes. As a measure for the pi-acceptor strength of (CN)(2)IMes compared to IMes, the selone (CN)(2)IMes center dot Se (7) was prepared and characterized by Se-77-NMR spectroscopy. The pi-acceptor strength of 7 was illuminated by the shift of its Se-77-NMR signal. The Se-77-NMR signal of 7 was shifted to much higher frequencies than the Se-77-NMR signal of IMes center dot Se. Catalytic experiments using the Mizoroki-Heck reaction of aryl chlorides with n-butyl acrylate showed that 6 is the superior performer in comparison to 4. Using complex 6, an extensive substrate screening of 26 different aryl bromides with n-butyl acrylate was performed. Complex 6 is a suitable precatalyst for para-substituted aryl bromides. The catalytically active species was identified by mercury poisoning experiments to be palladium nanoparticles.}, language = {en} } @article{BalciAkkayaAkyuzetal.2016, author = {Balci, K. and Akkaya, Y. and Akyuz, S. and Collier, W. B. and Stricker, M. C. and Stover, D. D. and Ritzhaupt, G. and Koch, Andreas and Kleinpeter, Erich}, title = {The effects of conformation and zwitterionic tautomerism on the structural and vibrational spectral data of anserine}, series = {Vibrational spectroscopy : an international journal devoted to applications of infrared and raman spectroscopy}, volume = {86}, journal = {Vibrational spectroscopy : an international journal devoted to applications of infrared and raman spectroscopy}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0924-2031}, doi = {10.1016/j.vibspec.2016.08.003}, pages = {277 -- 289}, year = {2016}, abstract = {In this study, the stable conformers of neutral anserine were searched by molecular dynamics simulations and energy minimization calculations using the MM2 force field. Thermochemical calculations at B3LYP/6-31G(d) level of theory followed these preliminary calculations. The results confirmed that neutral anserine has quite a flexible structure and many stable gauche and trans conformers at room temperature. Nevertheless, two are considerably more favourable in energy than the others and expected to dominate the gas-phase and matrix IR spectra of the molecule. The corresponding structural and vibrational spectral data for these two conformers of neutral anserine, whose relative stabilities were also examined by high-accuracy energy calculations carried out using G3MP2B3 method, and for the most stable conformer of anserine in zwitterion form were calculated at B3LYP/6-311++G(d,p) level of theory. The calculated harmonic force constants were refined using the Scaled Quantum Mechanical Force Field (SQM-FF) method and then used to produce the refined wavenumbers, potential energy distributions (PEDs) and IR and Raman intensities. These refined data together with the scaled harmonic wavenumbers obtained using another method, Dual Scale factors (DS), enabled us to correctly analyse the observed IR and Raman spectra of anserine and revealed the effects of conformation and zwitterionic tautomerism on its structural and vibrational spectral data. (C) 2016 Elsevier B.V. All rights reserved.}, language = {en} } @article{BalderasValadezAgarwalPacholski2016, author = {Balderas-Valadez, Ruth Fabiola and Agarwal, Vivechana and Pacholski, Claudia}, title = {Fabrication of porous silicon-based optical sensors using metal-assisted chemical etching}, series = {RSC Advances}, volume = {6}, journal = {RSC Advances}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2046-2069}, doi = {10.1039/c5ra26816h}, pages = {21430 -- 21434}, year = {2016}, abstract = {Optical biosensors based on porous silicon were fabricated by metal assisted chemical etching. Thereby double layered porous silicon structures were obtained consisting of porous pillars with large pores on top of a porous silicon layer with smaller pores. These structures showed a similar sensing performance in comparison to electrochemically produced porous silicon interferometric sensors.}, language = {en} } @article{BarazaNeserJacksonetal.2016, author = {Baraza, Lilechi D. and Neser, Wekesa and Jackson, Korir Cheruiyot and Fredrick, Juma B. and Dennis, Ochieno and Wairimu, Kamau R. and Keya, Aggrey Osogo and Heydenreich, Matthias}, title = {Antimicrobial Coumarins from the Oyster Culinary-Medicinal Mushroom, Pleurotus ostreatus (Agaricomycetes), from Kenya}, series = {International journal of medicinal mushrooms}, volume = {18}, journal = {International journal of medicinal mushrooms}, publisher = {Begell House}, address = {Danbury}, issn = {1521-9437}, doi = {10.1615/IntJMedMushrooms.v18.i10.60}, pages = {905 -- 913}, year = {2016}, abstract = {Pleurotus ostreatus has been widely used as food because of its nutritional and medicinal properties. These have been attributed to the presence of macronutrients, minerals, vitamins, and amino acids, among other secondary metabolites. There are, however, few reports on the antimicrobial activities of different classes of purified compounds from P. ostreatus. This led to the current study, the objective of which was to chemically characterize the antibiotic activities of P. ()streams against selected human pathogenic bacteria and endophytic fungi. Chemical structures were determined using spectroscopic methods and by comparison with values of related structures reported in the literature. Pure compounds from P. ostreatus were tested in vitro against pathogenic bacteria (Staphylococcus aureus and Escherichia coli) and endophytic fungi (Pencillium digitatum and Fusarium prolferatum). A new compound, (E)-5,7-dimethoxy-6-(3-methylbuta-1,3-dienyl)-2H-chromen-2-one (5-methoxy-(E)-suberodiene) (compound 2), along with ergosterol (compound I.) and 5,7-dimethoxy-6-(3-methylbut-2-enyl)-2H-chromen-2-one (toddaculin; compound 3), were isolated from the fruiting bodies of P. ostreatus. The growth of S. aureus,E proliferatum, and P. digitatum colonies was inhibited in media containing compound 2, with minimum inhibitory concentrations closely comparable to those of conventional antibiotics.}, language = {en} } @article{BartaSzatmariFueloepetal.2016, author = {Barta, Petra and Szatmari, Istvan and Fueloep, Ferenc and Heydenreich, Matthias and Koch, Andreas and Kleinpeter, Erich}, title = {Synthesis and stereochemistry of new naphth[1,3]oxazino[3,2-a] benzazepine and naphth[1,3]oxazino[3,2-e]thienopyridine derivatives}, series = {Tetrahedron}, volume = {72}, journal = {Tetrahedron}, publisher = {Elsevier}, address = {Oxford}, issn = {0040-4020}, doi = {10.1016/j.tet.2016.03.058}, pages = {2402 -- 2410}, year = {2016}, abstract = {Through the reactions of 1- or 2-naphthol and 4,5-dihydro-3H-benz[c]azepine or 6,7-dihydrothieno[3,2-c]pyridine, new aminonaphthol derivatives were prepared. The syntheses were extended by using N-containing naphthol analogues such as 5-hydroxyisoquinoline and 6-hydroxyquinoline. The ring closures of the novel bifunctional compounds were also achieved, resulting in new naphth[2,1-e][1,3]oxazines, naphth[1,2-e][1,3]oxazines, isoquinolino[5,6-e][1,3]oxazines and quinolino[5,6-e][1,3]oxazines. H-1 NMR spectra of the target heterocycles 16, 20 and 21 were sufficiently resolved to indentify the present stereochemistry; therefore, beside computed structures, spatial experimental (dipolar coupling-NOE) and computed (ring current effect of the naphthyl moiety-TSNMRS) NMR studies were employed. The studied heterocycles exist exclusively as S(14b),R(N), R(14b),S(N), and S(16b)S(N) isomers, respectively. The flexible moieties of the studied compounds prefer. (C) 2016 Elsevier Ltd. All rights reserved.}, language = {en} } @article{BauchBoettcherBornscheueretal.2016, author = {Bauch, Marcel and B{\"o}ttcher, Dominique and Bornscheuer, Uwe T. and Linker, Torsten}, title = {Enzymatic Cleavage of Aryl Acetates}, series = {ChemCatChem : heterogeneous \& homogeneous \& bio- \& nano-catalysis ; a journal of ChemPubSoc Europe}, volume = {8}, journal = {ChemCatChem : heterogeneous \& homogeneous \& bio- \& nano-catalysis ; a journal of ChemPubSoc Europe}, publisher = {Wiley-VCH}, address = {Weinheim}, organization = {HESS Collaboration}, issn = {1867-3880}, doi = {10.1002/cctc.201600678}, pages = {2853 -- 2857}, year = {2016}, abstract = {Seven enzymes have been screened for the cleavage of aryl acetates. Phenyl and naphthyl acetates react with lipases and esterases, whereas the sterically demanding anthracene acetate gave a conversion only with porcine liver esterase and esterase 2 from Bacillus subtilis (BS2). These two enzymes have been employed on a preparative (0.5 mmol) scale and afforded cleavage products in 91 and 94\% yields, even for anthracene acetate. Thus, this method is superior to chemical cleavage with catalytic amounts of sodium methoxide (Zemplen conditions), which gave only low conversions. Finally, regioselectivity has been achieved with an anthracene bisacetate, in which an ethyl group controls the cleavage of the first acetate. This indicates that steric interactions play a crucial role in the enzymatic cleavage of aryl acetates, which might be interesting for future applications or the development of enzyme inhibitors.}, language = {en} } @misc{BehrendtSchlaad2016, author = {Behrendt, Felix Nicolas and Schlaad, Helmut}, title = {Metathesis polymerization of cystine-based macrocycles}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-395080}, pages = {4}, year = {2016}, abstract = {Macrocycles based on L-cystine were synthesized by ring-closing metathesis (RCM) and subsequently polymerized by entropy-driven ring-opening metathesis polymerization (ED-ROMP). Monomer conversion reached ∼80\% in equilibrium and the produced poly(ester-amine-disulfide-alkene)s exhibited apparent molar masses (Mappw) of up to 80 kDa and dispersities (Đ) of ∼2. The polymers can be further functionalized with acid anhydrides and degraded by reductive cleavage of the main-chain disulfide.}, language = {en} }