@article{KirpichenkoShainyanKleinpeteretal.2018, author = {Kirpichenko, Svetlana and Shainyan, Bagrat A. and Kleinpeter, Erich and Shlykov, Sergey A. and Tran Dinh Phien, and Albanov, Alexander}, title = {Synthesis of 3-fluoro-3-methyl-3-silatetrahydropyran and its conformational preferences in gas and solution by GED, NMR and theoretical calculations}, series = {Tetrahedron}, volume = {74}, journal = {Tetrahedron}, number = {15}, publisher = {Elsevier}, address = {Oxford}, issn = {0040-4020}, doi = {10.1016/j.tet.2018.02.055}, pages = {1859 -- 1867}, year = {2018}, abstract = {The 3,3-disubstitued 3-silaheterocyclohexane with an electronegative substituent at silicon, 3-fluoro-3-methyl-3-silatetrahydropyran 1, was synthesized, and its molecular structure and conformational properties studied by gas-phase electron diffraction (GED) and low temperature C-13 and F-19 NMR spectroscopy. Quantum-chemical calculations were carried out both for the isolated species and Hcomplexes in gas and in polar medium. The predominance of the 1-FeqMeax conformer (1-F-eq:1-F-ax ratio of 65:35, Delta G degrees = 0.37 kcal/mol) determined from GED is close to the theoretically estimated conformational equilibrium, especially at the DFT level. In solution, low temperature NMR spectroscopy showed no decoalescence of the signals in C-13 (down to 95 K) and F-19 NMR spectra (down to 123 K). However, the calculated F-19 chemical shift of -173.6 ppm for the 1-FeqMeax conformer practically coincides with the experimentally observed value (-173 to -175 ppm) as distinct from that for the 1-FaxMeeq conformer (-188.8 ppm), suggesting compound 1 to be anancomeric in solution, in compliance with its theoretical and experimental preference in the gas phase.}, language = {en} } @article{RoderHille2018, author = {Roder, Phillip and Hille, Carsten}, title = {Local tissue manipulation via a force- and pressure-controlled AFM micropipette for analysis of cellular processes}, series = {Scientific reports}, volume = {8}, journal = {Scientific reports}, publisher = {Nature Publ. Group}, address = {London}, issn = {2045-2322}, doi = {10.1038/s41598-018-24255-9}, pages = {9}, year = {2018}, abstract = {Local manipulation of complex tissues at the single-cell level is challenging and requires excellent sealing between the specimen and the micromanipulation device. Here, biological applications for a recently developed loading technique for a force-and pressure-controlled fluidic force microscope micropipette are described. This technique allows for the exact positioning and precise spatiotemporal control of liquid delivery. The feasibility of a local loading technique for tissue applications was investigated using two fluorescent dyes, with which local loading behaviour could be optically visualised. Thus, homogeneous intracellular distribution of CellTracker Red and accumulation of SYTO 9 Green within nuclei was realised in single cells of a tissue preparation. Subsequently, physiological micromanipulation experiments were performed. Salivary gland tissue was pre-incubated with the Ca2+-sensitive dye OGB-1. An intracellular Ca2+ rise was then initiated at the single-cell level by applying dopamine via micropipette. When pre-incubating tissue with the nitric oxide (NO)-sensitive dye DAF-FM, NO release and intercellular NO diffusion was observed after local application of the NO donor SNP. Finally, local micromanipulation of a well-defined area along irregularly shaped cell surfaces of complex biosystems was shown for the first time for the fluidic force microscope micropipette. Thus, this technique is a promising tool for the investigation of the spatiotemporal effects of locally applied substances in complex tissues.}, language = {en} } @article{LiebigSarhanPrietzeletal.2018, author = {Liebig, Ferenc and Sarhan, Radwan Mohamed and Prietzel, Claudia Christina and Th{\"u}nemann, Andreas F. and Bargheer, Matias and Koetz, Joachim}, title = {Undulated Gold Nanoplatelet Superstructures}, series = {Langmuir}, volume = {34}, journal = {Langmuir}, number = {15}, publisher = {American Chemical Society}, address = {Washington}, issn = {0743-7463}, doi = {10.1021/acs.langmuir.7b02898}, pages = {4584 -- 4594}, year = {2018}, abstract = {Negatively charged flat gold nanotriangles, formed in a vesicular template phase and separated by an AOT-micelle-based depletion flocculation, were reloaded by adding a cationic polyelectrolyte, that is, a hyperbranched polyethylenimine (PEI). Heating the system to 100 degrees C in the presence of a gold chloride solution, the reduction process leads to the formation of gold nanoparticles inside the polymer shell surrounding the nanoplatelets. The gold nanoparticle formation is investigated by UV-vis spectroscopy, small-angle X-ray scattering, and dynamic light scattering measurements in combination with transmission electron microscopy. Spontaneously formed gold clusters in the hyperbranched PEI shell with an absorption maximum at 350 nm grow on the surface of the nanotriangles as hemispherical particles with diameters of similar to 6 nm. High-resolution micrographs show that the hemispherical gold particles are crystallized onto the {111} facets on the bottom and top of the platelet as well as on the edges without a grain boundary. Undulated gold nanoplatelet superstructures with special properties become available, which show a significantly modified performance in SERS-detected photocatalysis regarding both reactivity and enhancement factor.}, language = {en} } @article{WessigJohnMertens2018, author = {Wessig, Pablo and John, Leonard and Mertens, Monique}, title = {Extending the Class of [1,3]-Dioxolo[4.5-f]benzodioxole (DBD) Fluorescent Dyes}, series = {European journal of organic chemistry}, volume = {2018}, journal = {European journal of organic chemistry}, number = {14}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1434-193X}, doi = {10.1002/ejoc.201800002}, pages = {1674 -- 1681}, year = {2018}, abstract = {Synthetic routes to a collection of new fluorescent dyes are described, which are based on the [1,3]-dioxolo[4.5-f]benzodioxole (DBD) core. By introducing different electron withdrawing groups in 4- and 8-position of the DBD moiety the emission wavelength could be adjusted over a large spectral range from blue to orange light.}, language = {en} } @article{TianHuZhangetal.2018, author = {Tian, Guang-Zong and Hu, Jing and Zhang, Heng-Xi and Rademacher, Christoph and Zou, Xiao-Peng and Zheng, Hong-Ning and Xu, Fei and Wang, Xiao-Li and Linker, Torsten and Yin, Jian}, title = {Synthesis and conformational analysis of linear homo- and heterooligomers from novel 2-C-branched sugar amino acids (SAAs)}, series = {Scientific reports}, volume = {8}, journal = {Scientific reports}, publisher = {Nature Publ. Group}, address = {London}, issn = {2045-2322}, doi = {10.1038/s41598-018-24927-6}, pages = {8}, year = {2018}, abstract = {Sugar amino acids (SAAs), as biologically interesting structures bearing both amino and carboxylic acid functional groups represent an important class of multifunctional building blocks. In this study, we develop an easy access to novel SAAs in only three steps starting from nitro compounds in high yields in analytically pure form, easily available by ceric (IV) mediated radical additions. Such novel SAAs have been applied in the assembly of total nine carbopeptoids with the form of linear homo-and heterooligomers for the structural investigations employing circular dichroism (CD) spectroscopy, which suggest that the carbopeptoids emerge a well-extended, left (or right)-handed conformation similar to polyproline II (PPII) helices. NMR studies also clearly demonstrated the presence of ordered secondary structural elements. 2D-ROESY spectra were acquired to identify i+1NH <-> (C1H)-C-i, (C2H)-C-i correlations which support the conformational analysis of tetramers by CD spectroscopy. These findings provide interesting information of SAAs and their oligomers as potential scaffolds for discovering new drugs and materials.}, language = {en} } @article{JohnZimmermannBoeker2018, author = {John, Daniela and Zimmermann, Marc and B{\"o}ker, Alexander}, title = {Generation of 3-dimensional multi-patches on silica particles via printing with wrinkled stamps}, series = {Soft matter}, volume = {14}, journal = {Soft matter}, number = {16}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1744-683X}, doi = {10.1039/c8sm00224j}, pages = {3057 -- 3062}, year = {2018}, abstract = {A simple route towards patchy particles with anisotropic patches with respect to a different functionality and directionality is presented. This method is based on microcontact printing of positively charged polyethylenimine (PEI) on silica particles using wrinkled stamps. Due to the wrinkled surface, the number of patches on the particles as well as the distance between two patches can be controlled.}, language = {en} } @article{MaticSchlaad2018, author = {Matic, Aleksandar and Schlaad, Helmut}, title = {Thiol-ene photofunctionalization of 1,4-polymyrcene}, series = {Polymer international}, volume = {67}, journal = {Polymer international}, number = {5}, publisher = {Wiley}, address = {Hoboken}, issn = {0959-8103}, doi = {10.1002/pi.5534}, pages = {500 -- 505}, year = {2018}, abstract = {1,4-Polymyrcene was synthesized by anionic polymerization of -myrcene and was subjected to photochemical functionalization with various thiols (i.e. methyl thioglycolate, methyl 3-mercaptopropionate, butyl 3-mercaptopropionate, ethyl 2-mercaptopropionate and 2-methyl-2-propanethiol) using benzophenone/UV light as the radical source. The yield of thiol addition to the trisubstituted double bonds of 1,4-polymyrcene decreased in the order 1 degrees thiol (ca 95\%) > 2 degrees thiol (ca 80\%) > 3 degrees thiol (<5\%), due to the reversibility of the thiol-ene reaction. Remarkably, thiol addition to the side-chain double bonds was 8 - 10 times (1 degrees thiol) or 24 times (2 degrees thiol) faster than to the main-chain double bonds, which can be explained by the different accessibility of the double bonds and steric hindrance. Despite the use of a 10-fold excess of thiol with respect to myrcene units, the thiol-ene addition was accompanied by chain coupling reactions, which in the extreme case of 3 degrees thiol (or in the absence of thiol) resulted in the formation of insoluble crosslinked material. As an example, a methyl-thioglycolate-functionalized 1,4-polymyrcene was saponified/crosslinked to give submicron polyelectrolyte particles in dilute alkaline solution. (c) 2018 Society of Chemical Industry}, language = {en} } @article{PazHeydenreichSchmidtetal.2018, author = {Paz, Cristian and Heydenreich, Matthias and Schmidt, Bernd and Vadra, Nahir and Baggio, Ricardo}, title = {Three new dihydro-beta-agarofuran sesquiterpenes from the seeds of Maytenus boaria}, series = {Acta Crystallographica Section C}, volume = {74}, journal = {Acta Crystallographica Section C}, publisher = {International Union of Crystallography}, address = {Chester}, issn = {2053-2296}, doi = {10.1107/S2053229618005429}, pages = {564 -- 570}, year = {2018}, abstract = {As part of a project studying the secondary metabolites extracted from the Chilean flora, we report herein three new beta-agarofuran sesquiterpenes, namely (1S,4S,5S,6R,7R,8R,9R,10S)-6-acetoxy-4,9-dihydroxy-2,2,5a,9-tetramethyloctahydro-2H-3,9a-methanobenzo[b] oxepine-5,10-diylbis(furan-3-carboxylate), C27H32O11, (II), (1S,4S,5S,6R,7R,9S,10S)-6-acetoxy-9-hydroxy-2,2,5a, 9-tetramethyloctahydro-2H-3,9a-methanobenzo[ b] oxepine-5,10-diyl bis(furan-3-carboxylate), C27H32O10, (III), and (1S,4S,5S,6R,7R,9S,10S)-6-acetoxy-10-(benzoyloxy)-9-hydroxy-2,2,5a,9-tetramethyloctahydro-2H-3,9a-methanobenzo[b]oxepin-5-yl furan-3-carboxylate, C29H34O9, (IV), obtained from the seeds of Maytenus boaria and closely associated with a recently published relative [Paz et al. (2017). Acta Cryst. C73, 451-457]. In the (isomorphic) structures of (II) and (III), the central decalin system is esterified with an acetate group at site 1 and furoate groups at sites 6 and 9, and differ at site 8, with an OH group in (II) and no substituent in (III). This position is also unsubstituted in (IV), with site 6 being occupied by a benzoate group. The chirality of the skeletons is described as 1S, 4S, 5S, 6R, 7R, 8R, 9R, 10S in (II) and 1S, 4S, 5S, 6R, 7R, 9S, 10S in (III) and (IV), matching the chirality suggested by NMR studies. This difference in the chirality sequence among the title structures (in spite of the fact that the three skeletons are absolutely isostructural) is due to the differences in the environment of site 8, i.e. OH in (II) and H in (III) and (IV). This diversity in substitution, in turn, is responsible for the differences in the hydrogen-bonding schemes, which is discussed.}, language = {en} } @article{StarkeKochKammeretal.2018, author = {Starke, Ines and Koch, Andreas and Kammer, Stefan and Holdt, Hans-J{\"u}rgen and M{\"o}ller, Heiko Michael}, title = {Electrospray mass spectrometry and molecular modeling study of formation and stability of silver complexes with diazaperylene and bisisoquinoline}, series = {Journal of mass spectrometry}, volume = {53}, journal = {Journal of mass spectrometry}, number = {5}, publisher = {Wiley}, address = {Hoboken}, issn = {1076-5174}, doi = {10.1002/jms.4071}, pages = {408 -- 418}, year = {2018}, abstract = {The complex formation of the following diazaperylene ligands (L) 1,12-diazaperylene 1, 1,1-bisisoquinoline 2, 2,11-disubstituted 1,12-diazaperylenes (alkyl=methyl, ethyl, isopropyl, 3, 5, 7), 3,3-disubstituted 1,1-bisisoquinoline (alkyl=methyl, ethyl, isopropyl, 4, 6, 8 and with R=phenyl, 11 and with pyridine 12), and the 5,8-dimethoxy-substituted diazaperylene 9, 6,6-dimethoxy-substituted bisisoquinoline 10 with AgBF4 was investigated. Collision-induced dissociation measurements were used to evaluate the relative stabilities of the ligands themselves and for the [1:1](+) complexes as well as for the homoleptic and heteroleptic silver [1:2](+) complexes in the gas phase. This method is very useful in rapid screening of the stabilities of new complexes in the gas phase. The influence of the spatial arrangement of the ligands and the type of substituents employed for the complexation were examined. The effect of the preorganization of the diazaperylene on the threshold activation voltages and thus of the relative binding energies of the different complexes are discussed. Density functional theory calculations were used to calculate the optimized structures of the silver complexes and compared with the stabilities of the complexes in the gas phase for the first time.}, language = {en} } @article{Bouakline2018, author = {Bouakline, Foudhil}, title = {Unambiguous signature of the berry phase in intense laser dissociation of diatomic molecules}, series = {The journal of physical chemistry letters}, volume = {9}, journal = {The journal of physical chemistry letters}, number = {9}, publisher = {American Chemical Society}, address = {Washington}, issn = {1948-7185}, doi = {10.1021/acs.jpclett.8b00607}, pages = {2271 -- 2277}, year = {2018}, abstract = {We report strong evidence of Berry phase effects in intense laser dissociation of D-2(+) molecules, manifested as Aharonov-Bohm-like oscillations in the photofragment angular distribution (PAD). Our calculations show that this interference pattern strongly depends on the parity of the diatom initial rotational state, (-1)(j). Indeed, the PAD local maxima (minima) observed in one case (j odd) correspond to local minima (maxima) in the other case (j even). Using simple topological arguments, we clearly show that such interference conversion is a direct signature of the Berry phase. The sole effect of the latter on the rovibrational wave function is a sign change of the relative phase between two interfering components, which wind in opposite senses around a light-induced conical intersection (LICI). Therefore, encirclement of the LICI leads to constructive (j odd) or destructive (j even) self-interference of the initial nuclear wavepacket in the dissociative limit. To corroborate our theoretical findings, we suggest an experiment of strong-field indirect dissociation of D-2(+) molecules, comparing the PAD of the ortho and para molecular species in directions nearly perpendicular to the laser polarization axis.}, language = {en} } @article{MeilingCywinskiLoehmannsroeben2018, author = {Meiling, Till Thomas and Cywinski, Piotr J. and L{\"o}hmannsr{\"o}ben, Hans-Gerd}, title = {Two-Photon excitation fluorescence spectroscopy of quantum dots}, series = {The journal of physical chemistry : C, Nanomaterials and interfaces}, volume = {122}, journal = {The journal of physical chemistry : C, Nanomaterials and interfaces}, number = {17}, publisher = {American Chemical Society}, address = {Washington}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.7b12345}, pages = {9641 -- 9647}, year = {2018}, abstract = {The applications of quantum dots (QDs) in two-photon (2P) excitation applications demand reliable data about their 2P absorption (2PA) cross sections (sigma(2PA)). In the present study, sigma(2PA) values have been determined for a series of commercial colloidal CdSe/ZnS QDs and CdSeTe/ZnS QDs in aqueous media. For the first time for these QDs, the sigma(2PA) values have been determined over a wide spectral range, that is, between 720 and 900 nm, and are compared to the extinction coefficient (epsilon) values obtained under one-photon (1P) excitation. Furthermore, we present a QD in combination with an organic dye in a biotin-streptavidin Forster resonance energy transfer bioassay under 1P and 2P excitation. The results for the bioassay under 2P excitation are compared to those obtained under 1P excitation. The results demonstrate that in the case of the 2P excitation, higher sensitivity can be achieved because of an improved signal-to-noise ratio.}, language = {en} } @misc{Lendlein2018, author = {Lendlein, Andreas}, title = {Fabrication of reprogrammable shape-memory polymer actuators for robotics}, series = {Science robotics}, volume = {3}, journal = {Science robotics}, number = {18}, publisher = {American Assoc. for the Advancement of Science}, address = {Washington}, issn = {2470-9476}, doi = {10.1126/scirobotics.aat9090}, pages = {2}, year = {2018}, abstract = {Shape-memory polymer actuators, whose actuation geometry and switching temperatures are reprogrammable by physical fabrication schemes, were recently suggested for robotics with the option for self-healing and degradability.}, language = {en} } @article{SchultzeSchmidt2018, author = {Schultze, Christiane and Schmidt, Bernd}, title = {Prenylcoumarins in One or Two Steps by a Microwave-Promoted Tandem Claisen Rearrangement/Wittig Olefination/Cyclization Sequence}, series = {The journal of organic chemistry}, volume = {83}, journal = {The journal of organic chemistry}, number = {9}, publisher = {American Chemical Society}, address = {Washington}, issn = {0022-3263}, doi = {10.1021/acs.joc.8b00667}, pages = {5210 -- 5224}, year = {2018}, abstract = {The one-pot synthesis of 8-prenylcoumarins from 1,1-dimethylallylated salicylaldehydes and the stabilized ylide [(ethoxycarbonyl)methylene]triphenylphosphorane under microwave conditions was found to have a limited scope. The sequence suffers from a difficult and sometimes low-yielding synthesis of the precursors and from a competing deprenylation upon microwave irradiation. This side reaction occurs in particular with electron rich arenes with two or more alkoxy groups at adjacent positions, a prominent substitution pattern in naturally occurring 8-prenylcoumarins. Both limitations of this one-step sequence were overcome by a two-step synthesis consisting of a microwave-promoted tandem allyl ether Claisen rearrangement/Wittig olefination and a subsequent olefin cross metathesis with 2-methyl-2-butene. The cross metathesis step proceeds with a high selectivity and yields exclusively the desired prenyl, rather than the alternative crotyl substituent. Several naturally occurring 8-prenylcoumarins that were previously inaccessible have been synthesized in good overall yields along this route.}, language = {en} } @article{LeeHwangSchildeetal.2018, author = {Lee, Hui-Chun and Hwang, Jongkook and Schilde, Uwe and Antonietti, Markus and Matyjaszewski, Krzysztof and Schmidt, Bernhard V. K. J.}, title = {Toward ultimate control of radical polymerization}, series = {Chemistry of materials : a publication of the American Chemical Society}, volume = {30}, journal = {Chemistry of materials : a publication of the American Chemical Society}, number = {9}, publisher = {American Chemical Society}, address = {Washington}, issn = {0897-4756}, doi = {10.1021/acs.chemmater.8b00546}, pages = {2983 -- 2994}, year = {2018}, abstract = {Herein, an approach via combination of confined porous textures and reversible deactivation radical polymerization techniques is proposed to advance synthetic polymer chemistry, i.e., a connection of metal-organic frameworks (MOFs) and activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP). Zn-2(benzene-1,4-dicarboxylate)2(1,4-diazabicyclo[2.2.2]-octane) [Zn-2(bdc)(2)(dabco)] is utilized as a reaction environment for polymerization of various methacrylate monomers (methyl, ethyl, benzyl, and isobornyl methacrylate) in a confined nanochannel, resulting in polymers with control over dispersity, end functionalities, and tacticity with respect to distinct molecular size. To refine and reconsolidate the compartmentation effect on polymer regularity, initiator-functionalized Zn MOF was synthesized via cocrystallization with an initiator-functionalized ligand, 2-(2-bromo-2-methylpropanamido)-1,4-benzenedicarboxylate (Brbdc), in different ratios (10\%, 20\%, and 50\%). Through the embedded initiator, surface-initiated ARGET ATRP was directly initiated from the walls of the nanochannels. The obtained polymers had a high molecular weight up to 392 000. Moreover, a significant improvement in end-group functionality and stereocontrol was observed, entailing polymers with obvious increments in isotacticity. The results highlight a combination of MOFs and ATRP that is a promising and universal methodology to prepare various polymers with high molecular weight exhibiting well-defined uniformity in chain length and microstructure as well as the preserved chain-end functionality.}, language = {en} } @article{MeilingSchuermannVogeletal.2018, author = {Meiling, Till Thomas and Sch{\"u}rmann, Robin Mathis and Vogel, Stefanie and Ebel, Kenny and Nicolas, Christophe and Milosavljevic, Aleksandar R. and Bald, Ilko}, title = {Photophysics and Chemistry of Nitrogen-Doped Carbon Nanodots with High Photoluminescence Quantum Yield}, series = {The journal of physical chemistry : C, Nanomaterials and interfaces}, volume = {122}, journal = {The journal of physical chemistry : C, Nanomaterials and interfaces}, number = {18}, publisher = {American Chemical Society}, address = {Washington}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.8b00748}, pages = {10217 -- 10230}, year = {2018}, abstract = {Fluorescent carbon nanodots (CNDs) are very promising nanomaterials for a broad range of applications because of their high photostability, presumed selective luminescence, and low cost at which they can be produced. In this respect, CNDs are superior to well-established semiconductor quantum dots and organic dyes. However, reported synthesis protocols for CNDs typically lead to low photoluminescence quantum yield (PLQY) and low reproducibility, resulting in a poor understanding of the CND chemistry and photophysics. Here, we report a one-step synthesis of nitrogen-doped carbon nanodots (N-CNDs) from various carboxylic acids, Tris, and ethylenediaminetetraacetic acid resulting in high PLQY of up to 90\%. The reaction conditions in terms of starting materials, temperature, and reaction time are carefully optimized and their influence on the photophysical properties is characterized. We find that citric acid-derived N-CNDs can result in a very high PLQY of 90\%, but they do not show selective luminescence. By contrast, acetic acid-derived N-CNDs show selective luminescence but a PLQY of 50\%. The chemical composition of the surface and core of these two selected N-CND types is characterized among others by high-resolution synchrotron X-ray photoelectron spectroscopy using single isolated N-CND clusters. The results indicate that photoexcitation occurs in the N-CND core, whereas the emission properties are determined by the N-CND surface groups.}, language = {en} } @article{KarrasHolecBednarovaetal.2018, author = {Karras, Manfred and Holec, Jan and Bednarova, Lucie and Pohl, Radek and Schmidt, Bernd and Stara, Irena G. and Stary, Ivo}, title = {Asymmetric Synthesis of Nonracemic 2-Amino[6]helicenes and Their Self-Assembly into Langmuir Films}, series = {The journal of organic chemistry}, volume = {83}, journal = {The journal of organic chemistry}, number = {10}, publisher = {American Chemical Society}, address = {Washington}, issn = {0022-3263}, doi = {10.1021/acs.joc.8b00538}, pages = {5523 -- 5538}, year = {2018}, abstract = {Alternative ways of preparing nonracemic 2-amino[6]helicene derivatives were explored. The enantioselective [2 + 2 + 2] cycloisomerization of a nonchiral triyne under Ni(cod)(2)/(R)-QUINAP catalysis delivered the enantioenriched (+)-(P)-2-aminodibenzo[6]helicene derivative in 67\% ee. An ultimate "point-to-helical" chirality transfer was observed in the cyclization of enantiopure triynes mediated by Ni(CO)(2)(PPh3)(2) affording (-)-(M)- or (+)-(P)-7,8-bis(p-tolyl)hexahelicen-2-amine in >99\% ee as well as its benzoderivative in >99\% ee. The latter mode of stereocontrol was inefficient for a 2-aminobenzo[6]helicene congener with an embedded five-membered ring. The rac-, (-)-(M)-, and (+)-(P)-7,8-bis(p-tolyl)hexahelicen-2-amines formed Langmuir monolayers at the air water interface featuring practically identical surface pressure vs mean molecular area isotherms. The corresponding Langmuir-Blodgett films on quartz or silicon substrates were characterized by UV vis/ECD spectroscopy and AFM microscopy, respectively.}, language = {en} } @article{KimHeyneAbouserieetal.2018, author = {Kim, Yohan and Heyne, Benjamin and Abouserie, Ahed and Pries, Christopher and Ippen, Christian and G{\"u}nter, Christina and Taubert, Andreas and Wedel, Armin}, title = {CuS nanoplates from ionic liquid precursors-Application in organic photovoltaic cells}, series = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr}, volume = {148}, journal = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr}, number = {19}, publisher = {American Institute of Physics}, address = {Melville}, issn = {0021-9606}, doi = {10.1063/1.4991622}, pages = {10}, year = {2018}, abstract = {Hexagonal p-type semiconductor CuS nanoplates were synthesized via a hot injection method from bis(trimethylsilyl) sulfide and the ionic liquid precursor bis(N-dodecylpyridinium) tetrachloridocuprate( II). The particles have a broad size distribution with diameters between 30 and 680 nm and well-developed crystal habits. The nanoplates were successfully incorporated into organic photovoltaic (OPV) cells as hole conduction materials. The power conversion efficiency of OPV cells fabricated with the nanoplates is 16\% higher than that of a control device fabricated without the nanoplates. (C) 2018 Author(s).}, language = {en} } @article{RajuLiebigKlemkeetal.2018, author = {Raju, Rajarshi Roy and Liebig, Ferenc and Klemke, Bastian and Koetz, Joachim}, title = {pH-responsive magnetic Pickering Janus emulsions}, series = {Colloid and polymer science : official journal of the Kolloid-Gesellschaft}, volume = {296}, journal = {Colloid and polymer science : official journal of the Kolloid-Gesellschaft}, number = {6}, publisher = {Springer}, address = {New York}, issn = {0303-402X}, doi = {10.1007/s00396-018-4321-z}, pages = {1039 -- 1046}, year = {2018}, abstract = {We report ultrasonically generated pH-responsive Pickering Janus emulsions of olive oil and silicone oil with controllable droplet size and engulfment. Chitosan was used as a pH-responsive emulsifier. The increase of pH from 2 to 6 leads to a transition from completely engulfed double emulsion droplets to dumbbell-shaped Janus droplets accompanied by a significant decrease of droplet diameter and a more homogeneous size distribution. The results can be elucidated by the conformational change of chitosan from a more extended form at pH 2 to a more flexible form at pH 4-5. Magnetic responsiveness to the emulsion was attributed by dispersing superparamagnetic nanoparticles (Fe3O4 with diameter of 13 +/- 2 nm) in the olive oil phase before preparing the Janus emulsion. Incorporation of magnetic nanoparticles leads to superior emulsion stability, drastically reduced droplet diameters, and opened the way to control movement and orientation of the Janus droplets according to an external magnetic field.}, language = {en} } @article{FerrerPeresdosSantosetal.2018, author = {Ferrer, Beatriz and Peres, Tanara Vieira and dos Santos, Alessandra Antunes and Bornhorst, Julia and Morcillo, Patricia and Goncalves, Cinara Ludvig and Aschner, Michael}, title = {Methylmercury affects the expression of hypothalamic neuropeptides that control body weight in C57BL/6J mice}, series = {Toxicological sciences}, volume = {163}, journal = {Toxicological sciences}, number = {2}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {1096-6080}, doi = {10.1093/toxsci/kfy052}, pages = {557 -- 568}, year = {2018}, abstract = {Methylmercury (MeHg) is an environmental pollutant that affects primarily the central nervous system (CNS), causing neurological alterations. An early symptom of MeHg poisoning is the loss of body weight and appetite. Moreover, the CNS has an important role in controlling energy homeostasis. It is known that in the hypothalamus nutrient and hormonal signals converge to orchestrate control of body weight and food intake. In this study, we investigated if MeHg is able to induce changes in the expression of key hypothalamic neuropeptides that regulate energy homeostasis. Thus, hypothalamic neuronal mouse cell line GT 1-7 was treated with MeHg at different concentrations (0, 0.5, 1, and 5 mu M). MeHg induced the expression of the anorexigenic neuropeptide pro-omiomelanocortin (Pomc) and the orexigenic peptide Agouti-related peptide (Agrp) in a concentration-dependent manner, suggesting deregulation of mechanisms that control body weight. To confirm these in vitro observations, 8-week-old C57BL/6J mice (males and females) were exposed to MeHg in drinking water, modeling the most prevalent exposure route to this metal. After 30-day exposure, no changes in body weight were detected. However, MeHg treated males showed a significant decrease in fat depots. Moreover, MeHg affected the expression of hypothalamic neuropeptides that control food intake and body weight in a gender-and dose-dependent manner. Thus, MeHg increases Pomc mRNA only in males in a dose-dependent way, and it does not have effects on the expression of Agrp mRNA. The present study shows, for first time, that MeHg is able to induce changes in hypothalamic neuropeptides that regulate energy homeostasis, favoring an anorexigenic/catabolic profile.}, language = {en} } @article{SchoenemannLaschewskyRosenhahn2018, author = {Sch{\"o}nemann, Eric and Laschewsky, Andre and Rosenhahn, Axel}, title = {Exploring the long-term hydrolytic behavior of zwitterionic polymethacrylates and polymethacrylamides}, series = {Polymers}, volume = {10}, journal = {Polymers}, number = {6}, publisher = {MDPI}, address = {Basel}, issn = {2073-4360}, doi = {10.3390/polym10060639}, pages = {23}, year = {2018}, abstract = {The hydrolytic stability of polymers to be used for coatings in aqueous environments, for example, to confer anti-fouling properties, is crucial. However, long-term exposure studies on such polymers are virtually missing. In this context, we synthesized a set of nine polymers that are typically used for low-fouling coatings, comprising the well-established poly(oligoethylene glycol methylether methacrylate), poly(3-(N-2-methacryloylethyl-N,N-dimethyl) ammoniopropanesulfonate) (sulfobetaine methacrylate), and poly(3-(N-3-methacryamidopropyl-N,N-dimethyl)ammoniopropanesulfonate) (sulfobetaine methacrylamide) as well as a series of hitherto rarely studied polysulfabetaines, which had been suggested to be particularly hydrolysis-stable. Hydrolysis resistance upon extended storage in aqueous solution is followed by H-1 NMR at ambient temperature in various pH regimes. Whereas the monomers suffered slow (in PBS) to very fast hydrolysis (in 1 M NaOH), the polymers, including the polymethacrylates, proved to be highly stable. No degradation of the carboxyl ester or amide was observed after one year in PBS, 1 M HCl, or in sodium carbonate buffer of pH 10. This demonstrates their basic suitability for anti-fouling applications. Poly(sulfobetaine methacrylamide) proved even to be stable for one year in 1 M NaOH without any signs of degradation. The stability is ascribed to a steric shielding effect. The hemisulfate group in the polysulfabetaines, however, was found to be partially labile.}, language = {en} }