@article{WolffFrischmannSchulzeetal.2018, author = {Wolff, Christian Michael and Frischmann, Peter D. and Schulze, Marcus and Bohn, Bernhard J. and Wein, Robin and Livadas, Panajotis and Carlson, Michael T. and J{\"a}ckel, Frank and Feldmann, Jochen and W{\"u}rthner, Frank and Stolarczyk, Jacek K.}, title = {All-in-one visible-light-driven water splitting by combining nanoparticulate and molecular co-catalysts on CdS nanorods}, series = {Nature Energy}, volume = {3}, journal = {Nature Energy}, number = {10}, publisher = {Nature Publ. Group}, address = {London}, issn = {2058-7546}, doi = {10.1038/s41560-018-0229-6}, pages = {862 -- 869}, year = {2018}, abstract = {Full water splitting into hydrogen and oxygen on semiconductor nanocrystals is a challenging task; overpotentials must be overcome for both half-reactions and different catalytic sites are needed to facilitate them. Additionally, efficient charge separation and prevention of back reactions are necessary. Here, we report simultaneous H-2 and O-2 evolution by CdS nanorods decorated with nanoparticulate reduction and molecular oxidation co-catalysts. The process proceeds entirely without sacrificial agents and relies on the nanorod morphology of CdS to spatially separate the reduction and oxidation sites. Hydrogen is generated on Pt nanoparticles grown at the nanorod tips, while Ru(tpy)(bpy)Cl-2-based oxidation catalysts are anchored through dithiocarbamate bonds onto the sides of the nanorod. O-2 generation from water was verified by O-18 isotope labelling experiments, and time-resolved spectroscopic results confirmed efficient charge separation and ultrafast electron and hole transfer to the reaction sites. The system demonstrates that combining nanoparticulate and molecular catalysts on anisotropic nanocrystals provides an effective pathway for visible-light-driven photocatalytic water splitting.}, language = {en} } @article{CherstvyNagelBetaetal.2018, author = {Cherstvy, Andrey G. and Nagel, Oliver and Beta, Carsten and Metzler, Ralf}, title = {Non-Gaussianity, population heterogeneity, and transient superdiffusion in the spreading dynamics of amoeboid cells}, series = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, volume = {20}, journal = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, number = {35}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/c8cp04254c}, pages = {23034 -- 23054}, year = {2018}, abstract = {What is the underlying diffusion process governing the spreading dynamics and search strategies employed by amoeboid cells? Based on the statistical analysis of experimental single-cell tracking data of the two-dimensional motion of the Dictyostelium discoideum amoeboid cells, we quantify their diffusive behaviour based on a number of standard and complementary statistical indicators. We compute the ensemble- and time-averaged mean-squared displacements (MSDs) of the diffusing amoebae cells and observe a pronounced spread of short-time diffusion coefficients and anomalous MSD-scaling exponents for individual cells. The distribution functions of the cell displacements, the long-tailed distribution of instantaneous speeds, and the velocity autocorrelations are also computed. In particular, we observe a systematic superdiffusive short-time behaviour for the ensemble- and time-averaged MSDs of the amoeboid cells. Also, a clear anti-correlation of scaling exponents and generalised diffusivity values for different cells is detected. Most significantly, we demonstrate that the distribution function of the cell displacements has a strongly non-Gaussian shape andusing a rescaled spatio-temporal variablethe cell-displacement data collapse onto a universal master curve. The current analysis of single-cell motions can be implemented for quantifying diffusive behaviours in other living-matter systems, in particular, when effects of active transport, non-Gaussian displacements, and heterogeneity of the population are involved in the dynamics.}, language = {en} } @article{FudickarLinker2018, author = {Fudickar, Werner and Linker, Torsten}, title = {Release of Singlet Oxygen from Aromatic Endoperoxides by Chemical Triggers}, series = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition}, volume = {57}, journal = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition}, number = {39}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1433-7851}, doi = {10.1002/anie.201806881}, pages = {12971 -- 12975}, year = {2018}, abstract = {The generation of reactive singlet oxygen under mild conditions is of current interest in chemistry, biology, and medicine. We were able to release oxygen from dipyridylanthracene endoperoxides (EPOs) by using a simple chemical trigger at low temperature. Protonation and methylation of such EPOs strongly accelerated these reactions. Furthermore, the methyl pyridinium derivatives are water soluble and therefore serve as oxygen carriers in aqueous media. Methylation of the EPO of the ortho isomer affords the parent form directly without increasing the temperature under very mild conditions. This exceptional behavior is ascribed to the close contact between the nitrogen atom and the peroxo group. Singlet oxygen is released upon this reaction, and can be used to oxygenate an acceptor such as tetramethylethylene in the dark with no heating. Thus, a new chemical source of singlet oxygen has been found, which is triggered by a simple stimulus.}, language = {en} } @article{KocSimovichSchoenemannetal.2019, author = {Koc, Julian and Simovich, Tomer and Sch{\"o}nemann, Eric and Chilkoti, Ashutosh and Gardner, Harrison and Swain, Geoffrey W. and Hunsucker, Kelli and Laschewsky, Andr{\´e} and Rosenhahn, Axel}, title = {Sediment challenge to promising ultra-low fouling hydrophilic surfaces in the marine environment}, series = {Biofouling : the journal of bioadhesion and biofilm research}, volume = {35}, journal = {Biofouling : the journal of bioadhesion and biofilm research}, number = {4}, publisher = {Taylor \& Francis}, address = {London}, issn = {0892-7014}, doi = {10.1080/08927014.2019.1611790}, pages = {454 -- 462}, year = {2019}, abstract = {Hydrophilic coatings exhibit ultra-low fouling properties in numerous laboratory experiments. In stark contrast, the antifouling effect of such coatings in vitro failed when performing field tests in the marine environment. The fouling release performance of nonionic and zwitterionic hydrophilic polymers was substantially reduced compared to the controlled laboratory environment. Microscopy and spectroscopy revealed that a large proportion of the accumulated material in field tests contains inorganic compounds and diatomaceous soil. Diatoms adhered to the accumulated material on the coating, but not to the pristine polymer. Simulating field tests in the laboratory using sediment samples collected from the test sites showed that incorporated sand and diatomaceous earth impairs the fouling release characteristics of the coatings. When exposed to marine sediment from multiple locations, particulate matter accumulated on these coatings and served as attachment points for diatom adhesion and enhanced fouling. Future developments of hydrophilic coatings should consider accumulated sediment and its potential impact on the antifouling performance.}, language = {en} } @article{SchuckLehmannOllivieretal.2019, author = {Schuck, G{\"o}tz and Lehmann, Frederike and Ollivier, Jacques and Mutka, Hannu and Schorr, Susan}, title = {Influence of chloride substitution on the rotational dynamics of methylammonium in MAPbI(3-x)Cl(x) perovskites}, series = {The journal of physical chemistry : C, Nanomaterials and interfaces}, volume = {123}, 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.9b01238}, pages = {11436 -- 11446}, year = {2019}, abstract = {Hybrid halide perovskites, MAPbI(3), MAPbI(2.94)Cl(0.0)6, and MAPbCl(3) (MA, methylammonium), were investigated using inelastic and quasielastic neutron scattering (QENS) with the aim of elucidating the impact of chloride substitution on the rotational dynamics of MA. In this context, we discuss the influence of the inelastic neutron scattering caused by low-energy phonons on QENS, resulting from the MA rotational dynamics in MAPbI(3-x)Cl(x). Through a comparative temperature-dependent QENS investigation with different energy resolutions, which allow a wide Fourier time window, we achieved a consistent description of the influence of chlorine substitution in MAPbI(3) on the MA dynamics. Our results showed that chlorine substitution in the low-temperature orthorhombic phase leads to a weakening of the hydrogen bridge bonds, since the characteristic relaxation times of C-3 rotation at 70 K in MAPbCl(3) (135 ps) and MAPbI(2.94)Cl(0.06) (485 ps) are much shorter than that in MAPbI(3) (1635 ps). For the orthorhombic phase, we obtained the activitin energies from the temperature-dependent characteristic relaxation times tau (c3). by Arrhenius fits, indicating lower values of E-a for MAPbCl(3) and MAPbI(2.94)Cl(0.06) compared to that of MAPbI(3). We also performed QENS analyses at 190 K for all three samples. Here, we observed that MAPbCI(3) shows slower MA rotational dynamics than MAPbI(3) in the disordered structure.}, language = {en} } @article{UtechtGaebelKlamroth2018, author = {Utecht, Manuel Martin and Gaebel, Tina and Klamroth, Tillmann}, title = {Desorption induced by low energy charge carriers on Si(111)-7 x 7}, series = {Journal of computational chemistry : organic, inorganic, physical, biological}, volume = {39}, journal = {Journal of computational chemistry : organic, inorganic, physical, biological}, number = {30}, publisher = {Wiley}, address = {Hoboken}, issn = {0192-8651}, doi = {10.1002/jcc.25607}, pages = {2517 -- 2525}, year = {2018}, abstract = {We use clusters for the modeling of local ion resonances caused by low energy charge carriers in STM-induced desorption of benzene derivates from Si(111)-7 x 7. We perform Born-Oppenheimer molecular dynamics for the charged systems assuming vertical transitions to the charged states at zero temperature, to rationalize the low temperature activation energies, which are found in experiment for chlorobenzene. Our calculations suggest very similar low temperature activation energies for toluene and benzene. For the cationic resonance transitions to physisorption are found even at 0 K, while the anion remains chemisorbed during the propagations. Further, we also extend our previous static quantum chemical investigations to toluene and benzene. In addition, an in depth analysis of the ionization potentials and electron affinities, which are used to estimate resonance energies, is given.}, language = {en} } @article{DuyduBasaranAydinetal.2018, author = {Duydu, Yalcin and Basaran, Nursen and Aydin, Sevtap and Ustundag, Aylin and Yalcin, Can {\"O}zg{\"u}r and Anlar, Hatice Gul and Bacanli, Merve and Aydos, Kaan and Atabekoglu, Cem Somer and Golka, Klaus and Ickstadt, Katja and Schwerdtle, Tanja and Werner, Matthias and Meyer, S{\"o}ren and Bolt, Hermann M.}, title = {Evaluation of FSH, LH, testosterone levels and semen parameters in male boron workers under extreme exposure conditions}, series = {Archives of toxicology : official journal of EUROTOX}, volume = {92}, journal = {Archives of toxicology : official journal of EUROTOX}, number = {10}, publisher = {Springer}, address = {Heidelberg}, issn = {0340-5761}, doi = {10.1007/s00204-018-2296-7}, pages = {3051 -- 3059}, year = {2018}, abstract = {Boric acid and sodium borates are currently classified in the EU-CLP regulation as "toxic to reproduction" under "Category 1B", with hazard statement of H360FD. However, so far field studies on male reproduction in China and in Turkey could not confirm such boron-associated toxic effects. As validation by another independent study is still required, the present study has investigated possible boron-associated effects on male reproduction in workers (n = 212) under different boron exposure conditions. The mean daily boron exposure (DBE) and blood boron concentration of workers in the extreme exposure group (n = 98) were 47.17 +/- 17.47 (7.95-106.8) mg B/day and 570.6 +/- 160.1 (402.6-1100) ng B/g blood, respectively. Nevertheless, boron-associated adverse effects on semen parameters, as well as on FSH, LH and total testosterone levels were not seen, even within the extreme exposure group. With this study, a total body of evidence has accumulated that allows to conclude that male reproductive effects are not relevant to humans, under any feasible and realistic conditions of exposure to inorganic boron compounds.}, language = {en} } @article{YalcinkayaBresselLindneretal.2018, author = {Yalcinkaya, Hacer and Bressel, Katharina and Lindner, Peter and Gradzielski, Michael}, title = {Controlled formation of vesicles with added styrene and their fixation by polymerization}, series = {Journal of colloid and interface science}, volume = {531}, journal = {Journal of colloid and interface science}, publisher = {Elsevier}, address = {San Diego}, issn = {0021-9797}, doi = {10.1016/j.jcis.2018.07.097}, pages = {672 -- 680}, year = {2018}, abstract = {Hypothesis: An effective way for fixating vesicle structures is the insertion of monomers and cross-linking agents into their bilayer, and their subsequent polymerization can lead to the formation of polymeric nanocapsules. Particularly attractive here are vesicle systems that form spontaneously well-defined small vesicles, as obtaining such small nanocapsules with sizes below 100 nm is still challenging. Experiments: A spontaneously forming well-defined vesicle system composed of the surfactants TDMAO (tetradecyldimethylamine oxide), Pluronic L35, and LiPFOS (lithium perfluorooctylsulfonate) mixture was used as template for fixation by polymerization. Therefore, styrene monomer was incorporated into the vesicle bilayer and ultimately these structures were fixated by UV induced radical polymerization. Structural alteration of the vesicles upon loading with monomer and the cross-linker as well as the effect of subsequent polymerization in the membrane were investigated in detail by turbidity measurements, dynamic and static light scattering, (DLS, SLS), and small angle neutron scattering (SANS). Findings: The analysis showed the changes on vesicle structures due to the monomer loading, and that these structures can become permanently fixed by the polymerization process. The potential of this approach to produce well-defined nanocapsules starting from a self-assembled system and following polymerization is critically evaluated. (C) 2018 Elsevier Inc. All rights reserved.}, language = {en} } @article{GuentherKlaussToroNahuelpanetal.2019, author = {G{\"u}nther, Erika and Klauß, Andr{\´e} and Toro-Nahuelpan, Mauricio and Sch{\"u}ler, Dirk and Hille, Carsten and Faivre, Damien}, title = {The in vivo mechanics of the magnetotactic backbone as revealed by correlative FLIM-FRET and STED microscopy}, series = {Scientific reports}, volume = {9}, journal = {Scientific reports}, publisher = {Nature Publ. Group}, address = {London}, issn = {2045-2322}, doi = {10.1038/s41598-019-55804-5}, pages = {9}, year = {2019}, abstract = {Protein interaction and protein imaging strongly benefit from the advancements in time-resolved and superresolution fluorescence microscopic techniques. However, the techniques were typically applied separately and ex vivo because of technical challenges and the absence of suitable fluorescent protein pairs. Here, we show correlative in vivo fluorescence lifetime imaging microscopy Forster resonance energy transfer (FLIM-FRET) and stimulated emission depletion (STED) microscopy to unravel protein mechanics and structure in living cells. We use magnetotactic bacteria as a model system where two proteins, MamJ and MamK, are used to assemble magnetic particles called magnetosomes. The filament polymerizes out of MamK and the magnetosomes are connected via the linker MamJ. Our system reveals that bacterial filamentous structures are more fragile than the connection of biomineralized particles to this filament. More importantly, we anticipate the technique to find wide applicability for the study and quantification of biological processes in living cells and at high resolution.}, language = {en} } @article{Koetz2020, author = {Koetz, Joachim}, title = {The Effect of Surface Modification of Gold Nanotriangles for Surface-Enhanced Raman Scattering Performance}, series = {Nanomaterials}, volume = {10}, journal = {Nanomaterials}, number = {11}, publisher = {MDPI}, address = {Basel}, issn = {2079-4991}, doi = {10.3390/nano10112187}, pages = {13}, year = {2020}, abstract = {A surface modification of ultraflat gold nanotriangles (AuNTs) with different shaped nanoparticles is of special relevance for surface-enhanced Raman scattering (SERS) and the photo-catalytic activity of plasmonic substrates. Therefore, different approaches are used to verify the flat platelet morphology of the AuNTs by oriented overgrowth with metal nanoparticles. The most important part for the morphological transformation of the AuNTs is the coating layer, containing surfactants or polymers. By using well established AuNTs stabilized by a dioctyl sodium sulfosuccinate (AOT) bilayer, different strategies of surface modification with noble metal nanoparticles are possible. On the one hand undulated superstructures were synthesized by in situ growth of hemispherical gold nanoparticles in the polyethyleneimine (PEI)-coated AOT bilayer of the AuNTs. On the other hand spiked AuNTs were obtained by a direct reduction of Au³⁺ ions in the AOT double layer in presence of silver ions and ascorbic acid as reducing agent. Additionally, crumble topping of the smooth AuNTs can be realized after an exchange of the AOT bilayer by hyaluronic acid, followed by a silver-ion mediated reduction with ascorbic acid. Furthermore, a decoration with silver nanoparticles after coating the AOT bilayer with the cationic surfactant benzylhexadecyldimethylammonium chloride (BDAC) can be realized. In that case the ultraviolet (UV)-absorption of the undulated Au@Ag nanoplatelets can be tuned depending on the degree of decoration with silver nanoparticles. Comparing the Raman scattering data for the plasmon driven dimerization of 4-nitrothiophenol (4-NTP) to 4,4′-dimercaptoazobenzene (DMAB) one can conclude that the most important effect of surface modification with a 75 times higher enhancement factor in SERS experiments becomes available by decoration with gold spikes.}, language = {en} } @article{SchultzeSchmidt2019, author = {Schultze, Christiane and Schmidt, Bernd}, title = {Functionalized Benzofurans via Microwave-Promoted Tandem Claisen-Rearrangement/5-endo-dig Cyclization}, series = {Journal of heterocyclic chemistry}, volume = {56}, journal = {Journal of heterocyclic chemistry}, number = {9}, publisher = {Wiley}, address = {Hoboken}, issn = {0022-152X}, doi = {10.1002/jhet.3671}, pages = {2619 -- 2629}, year = {2019}, abstract = {Ortho-allyloxy alkinyl benzenes undergo, upon microwave irradiation in dimethylformamide, a tandem sequence of Claisen-rearrangement and 5-endo-dig cyclization to furnish 7-allyl-substituted benzofurans. With terminal alkynes, chroman-4-ones and enaminoketones become the main products. A mechanistic proposal for this observation relies on a reaction of the starting material with the solvent dimethylformamide under the microwave conditions.}, language = {en} } @article{NoteKoetzKosmella2006, author = {Note, Carine and Koetz, Joachim and Kosmella, Sabine}, title = {Structural changes in poly(ethyleneimine) modified microemulsion}, series = {Journal of colloid and interface science}, volume = {302}, journal = {Journal of colloid and interface science}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0021-9797}, doi = {10.1016/j.jcis.2006.06.071}, pages = {662 -- 668}, year = {2006}, abstract = {The influence of branched poly(ethyleneimine) on the phase behavior of the system sodium dodecylsulfate/toluene-pentanol (1:1)/water has been studied. The isotropic microemulsions still exist when water is replaced with aqueous solutions of PEI (up to 30\% in weight), but their stability is significantly influenced. From a polymer concentration of 20 wt\%, the polymer enhances the solubilization of water in oil, changes the sign of the spontaneous curvature of the surfactant film, and induces an inversion of the microemulsion type from water-in-oil (L-2) to oil-in-water (L-1), by the formation of a bicontinuous channel. Further investigations show that the addition of polymer in the L-2 phase changes the droplet-droplet interactions as the conductivity drops and the percolation disappears. In the bicontinuous channel, higher viscosities can be detected, as well as a weak percolation followed by a steep increase of the conductivity, which can be related to evident structural changes in the system. DSC measurements allow then to follow the changes of the water properties in the system, from interfacial-water in the L-2 phase to free-water in the sponge-like phase. Finally, all the measurements performed permit to characterize the structural transitions in the system and to understand the role of the added polymer.}, language = {en} } @article{WadeWoodColladoFregosoetal.2017, author = {Wade, Jessica and Wood, Sebastian and Collado-Fregoso, Elisa and Heeney, Martin and Durrant, James and Kim, Ji-Seon}, title = {Impact of Fullerene Intercalation on Structural and Thermal Properties of Organic Photovoltaic Blends}, series = {The journal of physical chemistry : C, Nanomaterials and interfaces}, volume = {121}, journal = {The journal of physical chemistry : C, Nanomaterials and interfaces}, publisher = {American Chemical Society}, address = {Washington}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.7b05893}, pages = {20976 -- 20985}, year = {2017}, abstract = {The performance of organic photovoltaic blend devices is critically dependent on the polymer:fullerene interface. These interfaces are expected to impact the structural and thermal properties of the polymer with regards to the conjugated backbone planarity and transition temperatures during annealing/cooling processes. Here, we report the impact of fullerene intercalation on structural and thermal properties of poly(2,5-bis(3-tetradecylthiophen-2-yOthieno[3,2-b]thiophene (PBTTT), a highly stable material known to exhibit liquid crystalline behavior. We undertake a detailed systematic study of the extent of intercalation in the PBTTT:fullerene blend, considering the use of four different fullerene derivatives and also varying the loading ratios. Resonant Raman spectroscopy allows morphology in situ during controlled heating and cooling. We find that small fullerene molecules readily intercalate into PBTTT crystallites, resulting in a planarization of the polymer backbone, but high fullerene loading ratios or larger fullerenes result in nonintercalated domains. During cooling from melt, nonintercalated blend films are found to return to their original morphology and reproduce all thermal transitions on cooling with minimal hysteresis. Intercalated blend films show significant hysteresis on cooling due to the crystallized fullerene attempting to reintercalate. The strongest hysteresis is for intercalated blend films with excess fullerene loading ratio, which form a distinct nanoribbon morphology and exhibit a reduced geminate recombination rate. These results reveal that careful consideration should be taken during device fabrication, as postdeposition thermal treatments significantly impact the charge generation and recombination dynamics.}, language = {en} } @article{FudickarLinker2017, author = {Fudickar, Werner and Linker, Torsten}, title = {Synthesis of Pyridylanthracenes and Their Reversible Reaction with Singlet Oxygen to Endoperoxides}, series = {The journal of organic chemistry}, volume = {82}, journal = {The journal of organic chemistry}, publisher = {American Chemical Society}, address = {Washington}, issn = {0022-3263}, doi = {10.1021/acs.joc.7b01765}, pages = {9258 -- 9262}, year = {2017}, abstract = {The ortho, meta, and para isomers of 9,10-dipyridylanthracene 1 have been synthesized and converted into their endoperoxides 1-O-2 upon oxidation with singlet oxygen. The kinetics of this reaction can be controlled by the substitution pattern and the solvent: in highly polar solvents, the meta isomer is the most reactive, whereas the ortho isomer is oxidized fastest in nonpolar solvents. Heating of the endoperoxides affords the parent anthracenes by release of singlet oxygen.}, language = {en} } @article{BauchKrtitschkaLinker2017, author = {Bauch, Marcel and Krtitschka, Angela and Linker, Torsten}, title = {Photooxygenation of oxygen-substituted naphthalenes}, series = {Journal of physical organic chemistry}, volume = {30}, journal = {Journal of physical organic chemistry}, publisher = {Wiley}, address = {Hoboken}, issn = {0894-3230}, doi = {10.1002/poc.3734}, pages = {6803 -- 6813}, year = {2017}, abstract = {The reaction of oxygen-substituted naphthalenes with singlet oxygen (O-1(2)) has been investigated, and labile endoperoxides have been isolated and characterized at -78 degrees C for the first time. Low-temperature kinetics by UV spectroscopy revealed that alkoxy and silyloxy substituents remarkably increase the rate of photooxygenations compared to 1,4-dimethylnaphthalene, whereas acyloxy-substituted acenes are inert towards O-1(2). The reactivities nicely correlate with HOMO energies and free activation energies, which we determined by density functional theory calculations. The lability of the isolated endoperoxides is due to their very fast back reaction to the corresponding naphthalenes even at -20 degrees C under release of O-1(2), making them to superior sources of this reactive species under very mild conditions. Finally, a carbohydrate-substituted naphthalene has been synthesized, which reacts reversibly with O-1(2) and might be applied for enantioselective oxidations in future work.}, language = {en} } @misc{IhmelsLinkerTrofimov2017, author = {Ihmels, Heiko and Linker, Torsten and Trofimov, Aleksei}, title = {Editorial}, series = {Journal of physical organic chemistry}, volume = {30}, journal = {Journal of physical organic chemistry}, publisher = {Wiley}, address = {Hoboken}, issn = {0894-3230}, doi = {10.1002/poc.3745}, pages = {1}, year = {2017}, language = {en} } @article{RyabchunSakhnoStumpeetal.2017, author = {Ryabchun, Alexander and Sakhno, Oksana and Stumpe, Joachim and Bobrovsky, Alexey}, title = {Full-Polymer Cholesteric Composites for Transmission and Reflection Holographic Gratings}, series = {Advanced optical materials}, volume = {5}, journal = {Advanced optical materials}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2195-1071}, doi = {10.1002/adom.201700314}, pages = {376 -- 379}, year = {2017}, abstract = {A new type of self-organized materials based on cholesteric networks filled with photoactive side-chain copolymer is being developed. Supramolecular helical structure of cholesteric polymer network resulting in the selective reflection is used as a photonic scaffold. Photochromic azobenzene-containing nematic copolymer is embedded in cholesteric scaffold and utilized as a photoactive media for optical pattering. 1D and 2D transmission diffraction gratings are successfully recorded in composite films by holographic technique. For the first time the possibility to create selective reflection gratings in cholesteric material mimicking the natural optical properties of cholesteric mesophase is demonstrated. That enables the coexistence of two selective gratings, where one has an intrinsic cholesteric periodic helical structure and the other is a holographic grating generated in photochromic polymer. The full-polymer composites provide high light-induced optical anisotropy due to effective photo-orientation of side-chain fragments of the azobenzene-containing liquid crystalline polymer, and prevent the degradation of the helical superstructure maintaining all optical properties of cholesteric mesophase. The proposed class of optical materials could be easily applied to a broad range of polymeric materials with specific functionality. The versatility of the adjustment and material preprogramming combined with high optical performance makes these materials a highly promising candidate for modern optical and photonic applications.}, language = {en} } @article{YangDingKochovskietal.2017, author = {Yang, Guang and Ding, Hong-ming and Kochovski, Zdravko and Hu, Rongting and Lu, Yan and Ma, Yu-qiang and Chen, Guosong and Jiang, Ming}, title = {Highly Ordered Self-Assembly of Native Proteins into 1D, 2D, and 3D Structures Modulated by the Tether Length of Assembly-Inducing Ligands}, series = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition}, volume = {56}, journal = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1433-7851}, doi = {10.1002/anie.201703052}, pages = {10691 -- 10695}, year = {2017}, abstract = {In nature, proteins self-assemble into various structures with different dimensions. To construct these nanostructures in laboratories, normally proteins with different symmetries are selected. However, most of these approaches are engineering-intensive and highly dependent on the accuracy of the protein design. Herein, we report that a simple native protein LecA assembles into one-dimensional nanoribbons and nanowires, two-dimensional nanosheets, and three-dimensional layered structures controlled mainly by small-molecule assembly-inducing ligands RnG (n = 1, 2, 3, 4, 5) with varying numbers of ethylene oxide repeating units. To understand the formation mechanism of the different morphologies controlled by the small-molecule structure, molecular simulations were performed from microscopic and mesoscopic view, which presented a clear relationship between the molecular structure of the ligands and the assembled patterns. These results introduce an easy strategy to control the assembly structure and dimension, which could shed light on controlled protein assembly.}, language = {en} } @article{GhaisariWinklhoferStrauchetal.2017, author = {Ghaisari, Sara and Winklhofer, Michael and Strauch, Peter and Klumpp, Stefan and Faivre, Damien}, title = {Magnetosome Organization in Magnetotactic Bacteria Unraveled by Ferromagnetic Resonance Spectroscopy}, series = {Biophysical journal}, volume = {113}, journal = {Biophysical journal}, publisher = {Cell Press}, address = {Cambridge}, issn = {0006-3495}, doi = {10.1016/j.bpj.2017.06.031}, pages = {637 -- 644}, year = {2017}, abstract = {Magnetotactic bacteria form assemblies of magnetic nanoparticles called magnetosomes. These magnetosomes are typically arranged in chains, but other forms of assemblies such as clusters can be observed in some species and genetic mutants. As such, the bacteria have developed as a model for the understanding of how organization of particles can influence the magnetic properties. Here, we use ferromagnetic resonance spectroscopy to measure the magnetic anisotropies in different strains of Magnetosprillum gtyphiswaldense MSR-1, a bacterial species that is amendable to genetic mutations. We combine our experimental results with a model describing the spectra. The model includes chain imperfections and misalignments following a Fisher distribution function, in addition to the intrinsic magnetic properties of the magnetosomes. Therefore, by applying the model to analyze the ferromagnetic resonance data, the distribution of orientations in the bulk sample can be retrieved in addition to the average magnetosome arrangement. In this way, we quantitatively characterize the magnetosome arrangement in both wild-type cells and Delta mamJ mutants, which exhibit differing magnetosome organization.}, language = {en} } @article{LangeWagnerZentel2006, author = {Lange, Birger and Wagner, J{\"u}rgen and Zentel, Rudolf}, title = {Fabrication of robust high-quality ORMOCER (R) inverse opals}, series = {Macromolecular rapid communications}, volume = {27}, journal = {Macromolecular rapid communications}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1022-1336}, doi = {10.1002/marc.200600429}, pages = {1746 -- 1751}, year = {2006}, abstract = {The nanostructuring of ORMOCER (R) to form inverse opals is described. For this purpose a polymer opal is used as a template and infiltrated with liquid ORMOCER (R). After photopolymerization of the resin the host opal is dissolved in tetrahydrofuran and an ORMOCER (R) inverse opal is obtained. It shows excellent periodicity (by SEM) and optical properties to reveal a high degree of face centered cubic order. This replication process leads to a nanostructured photonic crystal with the outstanding mechanical properties of ORMOCER (R) and high temperature stability up to 350 degrees C.}, language = {en} }