TY - JOUR A1 - Wade, Jessica A1 - Wood, Sebastian A1 - Collado-Fregoso, Elisa A1 - Heeney, Martin A1 - Durrant, James A1 - Kim, Ji-Seon T1 - Impact of Fullerene Intercalation on Structural and Thermal Properties of Organic Photovoltaic Blends JF - The journal of physical chemistry : C, Nanomaterials and interfaces N2 - 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. Y1 - 2017 U6 - https://doi.org/10.1021/acs.jpcc.7b05893 SN - 1932-7447 VL - 121 SP - 20976 EP - 20985 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Fudickar, Werner A1 - Linker, Torsten T1 - Synthesis of Pyridylanthracenes and Their Reversible Reaction with Singlet Oxygen to Endoperoxides JF - The journal of organic chemistry N2 - 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. Y1 - 2017 U6 - https://doi.org/10.1021/acs.joc.7b01765 SN - 0022-3263 VL - 82 SP - 9258 EP - 9262 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Bauch, Marcel A1 - Krtitschka, Angela A1 - Linker, Torsten T1 - Photooxygenation of oxygen-substituted naphthalenes JF - Journal of physical organic chemistry N2 - 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. KW - kinetics KW - labile peroxides KW - low-temperature experiments KW - naphthalenes KW - singlet oxygen Y1 - 2017 U6 - https://doi.org/10.1002/poc.3734 SN - 0894-3230 SN - 1099-1395 VL - 30 SP - 6803 EP - 6813 PB - Wiley CY - Hoboken ER - TY - GEN A1 - Ihmels, Heiko A1 - Linker, Torsten A1 - Trofimov, Aleksei T1 - Editorial T2 - Journal of physical organic chemistry Y1 - 2017 U6 - https://doi.org/10.1002/poc.3745 SN - 0894-3230 SN - 1099-1395 VL - 30 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Ryabchun, Alexander A1 - Sakhno, Oksana A1 - Stumpe, Joachim A1 - Bobrovsky, Alexey T1 - Full-Polymer Cholesteric Composites for Transmission and Reflection Holographic Gratings JF - Advanced optical materials N2 - 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. KW - azobenzene KW - cholesteric scaffolds KW - holography KW - LC polymer KW - polarization diffraction grating KW - reflection grating Y1 - 2017 U6 - https://doi.org/10.1002/adom.201700314 SN - 2195-1071 VL - 5 SP - 376 EP - 379 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Yang, Guang A1 - Ding, Hong-ming A1 - Kochovski, Zdravko A1 - Hu, Rongting A1 - Lu, Yan A1 - Ma, Yu-qiang A1 - Chen, Guosong A1 - Jiang, Ming T1 - Highly Ordered Self-Assembly of Native Proteins into 1D, 2D, and 3D Structures Modulated by the Tether Length of Assembly-Inducing Ligands JF - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition N2 - 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. KW - carbohydrate-protein interactions KW - dual non-covalent interactions KW - molecular simulations KW - protein self-assembly Y1 - 2017 U6 - https://doi.org/10.1002/anie.201703052 SN - 1433-7851 SN - 1521-3773 VL - 56 SP - 10691 EP - 10695 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Ghaisari, Sara A1 - Winklhofer, Michael A1 - Strauch, Peter A1 - Klumpp, Stefan A1 - Faivre, Damien T1 - Magnetosome Organization in Magnetotactic Bacteria Unraveled by Ferromagnetic Resonance Spectroscopy JF - Biophysical journal N2 - 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. Y1 - 2017 U6 - https://doi.org/10.1016/j.bpj.2017.06.031 SN - 0006-3495 SN - 1542-0086 VL - 113 SP - 637 EP - 644 PB - Cell Press CY - Cambridge ER - TY - JOUR A1 - Sprenger, Heike A1 - Erban, Alexander A1 - Seddig, Sylvia A1 - Rudack, Katharina A1 - Thalhammer, Anja A1 - Le, Mai Q. A1 - Walther, Dirk A1 - Zuther, Ellen A1 - Koehl, Karin I. A1 - Kopka, Joachim A1 - Hincha, Dirk K. T1 - Metabolite and transcript markers for the prediction of potato drought tolerance JF - Plant Biotechnology Journal N2 - Potato (Solanum tuberosum L.) is one of the most important food crops worldwide. Current potato varieties are highly susceptible to drought stress. In view of global climate change, selection of cultivars with improved drought tolerance and high yield potential is of paramount importance. Drought tolerance breeding of potato is currently based on direct selection according to yield and phenotypic traits and requires multiple trials under drought conditions. Marker-assisted selection (MAS) is cheaper, faster and reduces classification errors caused by noncontrolled environmental effects. We analysed 31 potato cultivars grown under optimal and reduced water supply in six independent field trials. Drought tolerance was determined as tuber starch yield. Leaf samples from young plants were screened for preselected transcript and nontargeted metabolite abundance using qRT-PCR and GC-MS profiling, respectively. Transcript marker candidates were selected from a published RNA-Seq data set. A Random Forest machine learning approach extracted metabolite and transcript markers for drought tolerance prediction with low error rates of 6% and 9%, respectively. Moreover, by combining transcript and metabolite markers, the prediction error was reduced to 4.3%. Feature selection from Random Forest models allowed model minimization, yielding a minimal combination of only 20 metabolite and transcript markers that were successfully tested for their reproducibility in 16 independent agronomic field trials. We demonstrate that a minimum combination of transcript and metabolite markers sampled at early cultivation stages predicts potato yield stability under drought largely independent of seasonal and regional agronomic conditions. KW - drought tolerance KW - machine learning KW - metabolite markers KW - potato (Solanum tuberosum) KW - prediction models KW - transcript markers Y1 - 2017 U6 - https://doi.org/10.1111/pbi.12840 SN - 1467-7644 SN - 1467-7652 VL - 16 IS - 4 SP - 939 EP - 950 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Schmidt, Marco F. A1 - Korb, Oliver A1 - Abell, Chris T1 - Antagonists of the miRNA-Argonaute 2 Protein Complex BT - Anti-miR-AGOs JF - Drug Target miRNA: Methods and Protocols N2 - microRNAs (miRNAs) have been identified as high-value drug targets. A widely applied strategy in miRNA inhibition is the use of antisense agents. However, it has been shown that oligonucleotides are poorly cell permeable because of their complex chemical structure and due to their negatively charged backbone. Consequently, the general application of oligonucleotides in therapy is limited. Since miRNAs’ functions are executed exclusively by the Argonaute 2 protein, we therefore describe a protocol for the design of a novel miRNA inhibitor class: antagonists of the miRNA-Argonaute 2 protein complex, so-called anti-miR-AGOs, that not only block the crucial binding site of the target miRNA but also bind to the protein’s active site. Due to their lower molecular weight and, thus, more drug-like chemical structure, the novel inhibitor class may show better pharmacokinetic properties than reported oligonucleotide inhibitors, enabling them for potential therapeutic use. KW - Drug design KW - microRNA KW - miRNA-Argonaute 2 protein complex KW - miRNA inhibitors KW - miRNA seed region Y1 - 2016 SN - 978-1-4939-6563-2 SN - 978-1-4939-6561-8 SN - 978-1-4939-8236-3 U6 - https://doi.org/10.1007/978-1-4939-6563-2_17 SN - 1064-3745 SN - 1940-6029 VL - 1517 SP - 239 EP - 249 PB - Springer CY - New York ER - TY - JOUR A1 - Balderas-Valadez, Ruth Fabiola A1 - Antunez, E. E. A1 - Olive-Mendez, Sion Federico A1 - Pacholski, Claudia A1 - Campos-Alvarez, Jose A1 - Bokhimi, Xim A1 - Agarwal, V. T1 - Porous silicon pillar and bilayer structure as a nucleation center for the formation of aligned vanadium pentoxide nanorods JF - Ceramics International N2 - Porous silicon single layer (PSM), bilayer (PSB) and pillar (PSP) structures have been evaluated as nucleation centers for vanadium pentoxide (V2O5) crystals. Deposition of vanadium precursor over different substrates (drop casting technique), followed by annealing treatment under Ar-H-2 (5% H-2) atmosphere, induced crystallization of vanadium oxide. With respect to c-Si/SiO2 substrate, V2O5 nanorods with relatively large aspect ratio were formed over and within PSP structures. On the other hand, pores in PSM and PSB were found to be filled with relatively smaller crystals. Additionally, PSB provided a nucleation substrate capable to align the nanocrystals in a preferential orientation, while V2O5 crystals grown on PSP were found to be randomly aligned around the nanoporous pillar microstructure. Nanorods and nanocrystals were identified as V2O5 by temperature-controlled XRD measurements and evidence of their crystalline nature was observed via transmission electron microscopy. A careful analysis of electronic microscopy images allows the identification of the facets composing the ends of the crystals and its corresponding surface free energy has been evaluated employing the Wulff theorem. Such high surface area composite structures have potential applications as cathode material in Lithium-ion batteries. KW - Porous silicon KW - Vanadium pentoxide KW - Nanorods KW - Crystallization KW - Nanostructures Y1 - 2017 U6 - https://doi.org/10.1016/j.ceramint.2017.03.114 SN - 0272-8842 SN - 1873-3956 VL - 43 SP - 8023 EP - 8030 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Marco, Makungu A1 - Deyou, Tsegaye A1 - Gruhonjic, Amra A1 - Holleran, John A1 - Duffy, Sandra A1 - Heydenreich, Matthias A1 - Firtzpatrick, Paul A. A1 - Landberg, Goran A1 - Koch, Andreas A1 - Derese, Solomon A1 - Pelletier, Jerry A1 - Avery, Vicky M. A1 - Erdelyi, Mate A1 - Yenesew, Abiy T1 - Pterocarpans and isoflavones from the root bark of Millettia micans and of Millettia dura JF - Phytochemistry letters KW - Millettia micans KW - Millettia dura KW - Pterocarpan KW - Isoflavone KW - Cytotoxicity KW - Plasmodium falciparum Y1 - 2017 U6 - https://doi.org/10.1016/j.phytol.2017.07.012 SN - 1874-3900 SN - 1876-7486 VL - 21 SP - 216 EP - 220 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Atilaw, Yoseph A1 - Duffy, Sandra A1 - Heydenreich, Matthias A1 - Muiva-Mutisya, Lois A1 - Avery, Vicky M. A1 - Erdelyi, Mate A1 - Yenesew, Abiy T1 - Three Chalconoids and a Pterocarpene from the Roots of Tephrosia aequilata JF - Molecules N2 - In our search for new antiplasmodial agents, the CH2Cl2/CH3OH (1:1) extract of the roots of Tephrosia aequilata was investigated, and observed to cause 100% mortality of the chloroquine-sensitive (3D7) strain of Plasmodium falciparum at a 10 mg/mL concentration. From this extract three new chalconoids, E-2,6-dimethoxy-3,4-(2,2-dimethyl)pyranoretrochalcone (1, aequichalcone A), Z-2,6-dimethoxy-3,4-(2,2-dimethyl)pyranoretrochalcone (2, aequichalcone B), 4-ethoxy-3-hydroxypraecansone B (3, aequichalcone C) and a new pterocarpene, 3,4:8,9-dimethylenedioxy-6a,11a-pterocarpene (4), along with seven known compounds were isolated. The purified compounds were characterized by NMR spectroscopic and mass spectrometric analyses. Compound 1 slowly converts into 2 in solution, and thus the latter may have been enriched, or formed, during the extraction and separation process. The isomeric compounds 1 and 2 were both observed in the crude extract. Some of the isolated constituents showed good to moderate antiplasmodial activity against the chloroquine-sensitive (3D7) strain of Plasmodium falciparum. KW - Tephrosia aequilata KW - chalcone KW - retrochalcone KW - aequichalcone A KW - aequichalcone B KW - aequichalcone C KW - pterocarpene KW - antiplasmodial Y1 - 2017 U6 - https://doi.org/10.3390/molecules22020318 SN - 1420-3049 VL - 22 IS - 2 PB - MDPI CY - Basel ER - TY - GEN A1 - Naolou, Toufik A1 - Rühl, Eckart A1 - Lendlein, Andreas T1 - Nanocarriers BT - Architecture, transport, and topical application of drugs for therapeutic use T2 - European Journal of Pharmaceutics and Biopharmaceutics Y1 - 2017 U6 - https://doi.org/10.1016/j.ejpb.2017.03.004 SN - 0939-6411 SN - 1873-3441 VL - 116 SP - 1 EP - 3 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Utecht, Manuel Martin A1 - Palmer, Richard E. A1 - Klamroth, Tillmann T1 - Quantum chemical approach to atomic manipulation of chlorobenzene on the Si(111)-7 x 7 surface BT - Resonance localization, vibrational activation, and surface dynamics JF - Physical review materials N2 - We present a cluster model to describe the localization of hot charge carriers on the Si(111)-7 x 7 surface, which leads to (nonlocal) desorption of chlorobenzene molecules in scanning tunneling microscope (STM) manipulation experiments. The localized charge carriers are modeled by a small cluster. By means of quantum chemical calculations, this cluster model explains many experimental findings from STM manipulation. We show that the negative charge is mainly localized in the surface, while the positive one also resides on the molecule. Both resonances boost desorption: In the negative resonance the adatom is elevated; in the positive one the chemisorption bond between the silicon surface adatom and chlorobenzene is broken. We find normal modes promoting desorption matching experimental low-temperature activation energies for electron-and hole-induced desorption. Y1 - 2017 U6 - https://doi.org/10.1103/PhysRevMaterials.1.026001 SN - 2475-9953 VL - 1 IS - 2 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Wolf, Thomas J. A. A1 - Holzmeier, Fabian A1 - Wagner, Isabella A1 - Berrah, Nora A1 - Bostedt, Christoph A1 - Bozek, John A1 - Bucksbaum, Phil A1 - Coffee, Ryan A1 - Cryan, James A1 - Farrell, Joe A1 - Feifel, Raimund A1 - Martinez, Todd J. A1 - McFarland, Brian A1 - Mucke, Melanie A1 - Nandi, Saikat A1 - Tarantelli, Francesco A1 - Fischer, Ingo A1 - Gühr, Markus T1 - Observing Femtosecond Fragmentation Using Ultrafast X-ray-Induced Auger Spectra JF - Applied sciences N2 - Molecules often fragment after photoionization in the gas phase. Usually, this process can only be investigated spectroscopically as long as there exists electron correlation between the photofragments. Important parameters, like their kinetic energy after separation, cannot be investigated. We are reporting on a femtosecond time-resolved Auger electron spectroscopy study concerning the photofragmentation dynamics of thymine. We observe the appearance of clearly distinguishable signatures from thymines neutral photofragment isocyanic acid. Furthermore, we observe a time-dependent shift of its spectrum, which we can attribute to the influence of the charged fragment on the Auger electron. This allows us to map our time-dependent dataset onto the fragmentation coordinate. The time dependence of the shift supports efficient transformation of the excess energy gained from photoionization into kinetic energy of the fragments. Our method is broadly applicable to the investigation of photofragmentation processes. KW - ultrafast dynamics KW - Auger electron spectroscopy KW - photofragmentation KW - photochemistry Y1 - 2017 U6 - https://doi.org/10.3390/app7070681 SN - 2076-3417 VL - 7 IS - 7 PB - MDPI CY - Basel ER - TY - JOUR A1 - Selemani, Ramadhani Selemani Omari A1 - Nondo, Omari A1 - Moshi, Mainen Julius A1 - Erasto, Paul A1 - Masimba, Pax Jessey A1 - Machumi, Francis A1 - Kidukuli, Abdul Waziri A1 - Heydenreich, Matthias A1 - Zofou, Denis T1 - Anti-plasmodial activity of Norcaesalpin D and extracts of four medicinal plants used traditionally for treatment of malaria JF - BMC Complementary and Alternative Medicine volume N2 - Background: Malaria is an old life-threatening parasitic disease that is still affecting many people, mainly children living in sub-Saharan Africa. Availability of effective antimalarial drugs played a significant role in the treatment and control of malaria. However, recent information on the emergence of P. falciparum parasites resistant to one of the artemisinin-based combination therapies suggests the need for discovery of new drug molecules. Therefore, this study aimed to evaluate the antiplasmodial activity of extracts, fractions and isolated compound from medicinal plants traditionally used in the treatment of malaria in Tanzania. Methods: Dry powdered plant materials were extracted by cold macerations using different solvents. Norcaesalpin D was isolated by column chromatography from dichloromethane root extract of Caesalpinia bonducella and its structure was assigned based on the spectral data. Crude extracts, fractions and isolated compound were evaluated for antiplasmodial activity against chloroquine-sensitive P. falciparum (3D7), chloroquine-resistant P. falciparum (Dd2, K1) and artemisinin-resistant P. falciparum (IPC 5202 Battambang, IPC 4912 Mondolkiri) strains using the parasite lactate dehydrogenase assay. Results: The results indicated that extracts of Erythrina schliebenii, Holarrhena pubescens, Dissotis melleri and C. bonducella exhibited antiplasmodial activity against Dd2 parasites. Ethanolic root extract of E. schliebenii had an IC50 of 1.87 mu g/mL while methanolic and ethanolic root extracts of H. pubescens exhibited an IC50 = 2.05 mu g/mL and IC50 = 2.43 mu g/mL, respectively. Fractions from H. pubescens and C. bonducella roots were found to be highly active against K1, Dd2 and artemisinin-resistant parasites. Norcaesalpin D from C. bonducella root extract was active with IC50 of 0.98, 1.85 and 2.13 mu g/mL against 3D7, Dd2 and IPC 4912-Mondolkiri parasites, respectively. Conclusions: Antiplasmodial activity of norcaesalpin D and extracts of E. schliebenii, H. pubescens, D. melleri and C. bonducella reported in this study requires further attention for the discovery of antimalarial lead compounds for future drug development. KW - Antiplasmodial KW - norcaesalpin D KW - E. schliebenii KW - H. pubescens KW - D. melleri KW - C. bonducella Y1 - 2017 U6 - https://doi.org/10.1186/s12906-017-1673-8 SN - 1472-6882 VL - 17 PB - BioMed Central CY - London ER - TY - JOUR A1 - Meyners, Christian A1 - Mertens, Monique A1 - Wessig, Pablo A1 - Meyer-Almes, Franz-Josef T1 - A Fluorescence-Lifetime-Based Binding Assay for Class IIa Histone Deacetylases JF - Chemistry - a European journal N2 - Class IIa histone deacetylases (HDACs) show extremely low enzymatic activity and no commonly accepted endogenous substrate is known today. Increasing evidence suggests that these enzymes exert their effect rather through molecular recognition of acetylated proteins and recruiting other proteins like HDAC3 to the desired target location. Accordingly, class IIa HDACs like bromodomains have been suggested to act as “Readers” of acetyl marks, whereas enzymatically active HDACs of class I or IIb are called “Erasers” to highlight their capability to remove acetyl groups from acetylated histones or other proteins. Small-molecule ligands of class IIa histone deacetylases (HDACs) have gained tremendous attention during the last decade and have been suggested as pharmaceutical targets in several indication areas such as cancer, Huntington's disease and muscular atrophy. Up to now, only enzyme activity assays with artificial chemically activated trifluoroacetylated substrates are in use for the identification and characterization of new active compounds against class IIa HDACs. Here, we describe the first binding assay for this class of HDAC enzymes that involves a simple mix-and-measure procedure and an extraordinarily robust fluorescence lifetime readout based on [1,3]dioxolo[4,5-f]benzodioxole-based ligand probes. The principle of the assay is generic and can also be transferred to class I HDAC8. KW - drug discovery KW - enzymes KW - fluorescent probes KW - high-throughput screening KW - hydrolases Y1 - 2017 U6 - https://doi.org/10.1002/chem.201605140 SN - 0947-6539 SN - 1521-3765 VL - 23 IS - 13 SP - 3107 EP - 3116 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Ehlert, Christopher A1 - Klamroth, Tillmann T1 - The quest for best suited references for configuration interaction singles calculations of core excited states JF - Journal of computational chemistry : organic, inorganic, physical, biological N2 - Near edge X-ray absorption fine structure (NEXAFS) simulations based on the conventional configuration interaction singles (CIS) lead to excitation energies, which are systematically blue shifted. Using a (restricted) open shell core hole reference instead of the Hartree Fock (HF) ground state orbitals improves (Decleva et al., Chem. Phys., 1992, 168, 51) excitation energies and the shape of the spectra significantly. In this work, we systematically vary the underlying SCF approaches, that is, based on HF or density functional theory, to identify best suited reference orbitals using a series of small test molecules. We compare the energies of the K edges and NEXAFS spectra to experimental data. The main improvement compared to conventional CIS, that is, using HF ground state orbitals, is due to the electrostatic influence of the core hole. Different SCF approaches, density functionals, or the use of fractional occupations lead only to comparably small changes. Furthermore, to account for bigger systems, we adapt the core-valence separation for our approach. We demonstrate that the good quality of the spectrum is not influenced by this approximation when used together with the non-separated ground state wave function. Simultaneously, the computational demands are reduced remarkably. (C) 2016 Wiley Periodicals, Inc. KW - core excited states KW - configuration interaction KW - near edge X-ray absorption fine structure Y1 - 2016 U6 - https://doi.org/10.1002/jcc.24531 SN - 0192-8651 SN - 1096-987X VL - 38 SP - 116 EP - 126 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - von Klitzing, Regine A1 - Stehl, Dimitrij A1 - Pogrzeba, Tobias A1 - Schomaäcker, Reinhard A1 - Minullina, Renata A1 - Panchal, Abhishek A1 - Konnova, Svetlana A1 - Fakhrullin, Rawil A1 - Koetz, Joachim A1 - Moehwald, Helmuth A1 - Lvov, Yuri T1 - Halloysites Stabilized Emulsions for Hydroformylation of Long Chain Olefins JF - Advanced materials interfaces N2 - Halloysites as tubular alumosilicates are introduced as inexpensive natural nanoparticles to form and stabilize oil-water emulsions. This stabilized emulsion is shown to enable efficient interfacial catalytic reactions. Yield, selectivity, and product separation can be tremendously enhanced, e.g., for the hydroformylation reaction of dodecene to tridecanal. In perspective, this type of formulation may be used for oil spill dispersions. The key elements of the described formulations are clay nanotubes (halloysites) which are highly anisometric, can be filled by helper molecules, and are abundantly available in thousands of tons, making this technology scalable for industrial applications. Y1 - 2016 U6 - https://doi.org/10.1002/admi.201600435 SN - 2196-7350 VL - 4 IS - 1 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Schweighöfer, F. A1 - Moreno, J. A1 - Bobone, Sara A1 - Chiantia, Salvatore A1 - Herrmann, A. A1 - Hecht, S. A1 - Wachtveitl, Josef T1 - Connectivity pattern modifies excited state relaxation dynamics of fluorophore-photoswitch molecular dyads JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - In order to modulate the emission of BODIPY fluorophores, they were connected to a diarylethene (DAE) photoswitch via phenylene-ethynylene linkers of different lengths and orientations. The latter allowed for modulation of the electronic coupling in the prepared four BODIPY-DAE dyads, which were compared also to appropriate BODIPY and DAE model compounds by steady state as well as time-resolved spectroscopies. In their open isomers, all dyads show comparable luminescence behavior indicative of an unperturbed BODIPY fluorophore. In strong contrast, in the closed isomers the BODIPY emission is efficiently quenched but the deactivation mechanism depends on the nature of the linker. The most promising dyad was rendered water-soluble by means of micellar encapsulation and aqueous suspensions were investigated by fluorescence spectroscopy and microscopy. Our results (i) illustrate that the electronic communication between the BODIPY and DAE units can indeed be fine-tuned by the nature of the linker to achieve fluorescence modulation while maintaining photoswitchability and (ii) highlight potential applications to image and control biological processes with high spatio-temporal resolution. Y1 - 2016 U6 - https://doi.org/10.1039/c6cp07112k SN - 1463-9076 SN - 1463-9084 VL - 19 SP - 4010 EP - 4018 PB - Royal Society of Chemistry CY - Cambridge ER -