Recent Submissions

  • Chick chorioallantoic membrane assay as an in vivo model to study the effect of nanoparticle-based anticancer drugs in ovarian cancer

    Vu, Binh Thanh; Shahin, Sophia Allaf; Croissant, Jonas G.; Fatieiev, Yevhen; Matsumoto, Kotaro; Le-Hoang Doan, Tan; Yik, Tammy; Simargi, Shirleen; Conteras, Altagracia; Ratliff, Laura; Jimenez, Chiara Mauriello; Raehm, Laurence; Khashab, Niveen M.; Durand, Jean-Olivier; Glackin, Carlotta; Tamanoi, Fuyuhiko (Scientific Reports, Springer Nature, 2018-05-29) [Article]
    New therapy development is critically needed for ovarian cancer. We used the chicken egg CAM assay to evaluate efficacy of anticancer drug delivery using recently developed biodegradable PMO (periodic mesoporous organosilica) nanoparticles. Human ovarian cancer cells were transplanted onto the CAM membrane of fertilized eggs, resulting in rapid tumor formation. The tumor closely resembles cancer patient tumor and contains extracellular matrix as well as stromal cells and extensive vasculature. PMO nanoparticles loaded with doxorubicin were injected intravenously into the chicken egg resulting in elimination of the tumor. No significant damage to various organs in the chicken embryo occurred. In contrast, injection of free doxorubicin caused widespread organ damage, even when less amount was administered. The lack of toxic effect of nanoparticle loaded doxorubicin was associated with specific delivery of doxorubicin to the tumor. Furthermore, we observed excellent tumor accumulation of the nanoparticles. Lastly, a tumor could be established in the egg using tumor samples from ovarian cancer patients and that our nanoparticles were effective in eliminating the tumor. These results point to the remarkable efficacy of our nanoparticle based drug delivery system and suggests the value of the chicken egg tumor model for testing novel therapies for ovarian cancer.
  • Efficient Photon Recycling and Radiation Trapping in Cesium Lead Halide Perovskite Waveguides

    Dursun, Ibrahim; Zheng, Yangzi; Guo, Tianle; de Bastiani, Michele; Turedi, Bekir; Sinatra, Lutfan; Haque, Mohammed; Sun, Bin; Zhumekenov, Ayan A.; Saidaminov, Makhsud I.; Garcia de Arquer, F. Pelayo; Sargent, Edward H.; Wu, Tao; Gartstein, Yuri N; Bakr, Osman; Mohammed, Omar F.; Malko, Anton V. (ACS Energy Letters, American Chemical Society (ACS), 2018-05-26) [Article]
    Cesium lead halide perovskite materials have attracted considerable attention for potential applications in lasers, light emitting diodes and photodetectors. Here, we provide the experimental and theoretical evidence for photon recycling in CsPbBr3 perovskite microwires. Using two-photon excitation, we recorded photoluminescence (PL) lifetimes and emission spectra as a function of the lateral distance between PL excitation and collection positions along the microwire, with separations exceeding 100 µm. At longer separations, the PL spectrum develops a red-shifted emission peak accompanied by an appearance of well-resolved rise times in the PL kinetics. We developed quantitative modeling that accounts for bimolecular recombination and photon recycling within the microwire waveguide and is sufficient to account for the observed decay modifications. It relies on a high radiative efficiency in CsPbBr3 perovskite microwires and provides crucial information about the potential impact of photon recycling and waveguide trapping on optoelectronic properties of cesium lead halide perovskite materials.
  • Synthesis of an oxo trialkyl tungsten fluoride complex and its dual reactivity with silica dehydroxylated at high temperature

    Merle, Nicolas; Mazoyer, Etienne; Szeto, Kai C.; Rouge, Pascal; de Mallmann, Aimery; Berrier, Elise; Delevoye, Laurent; Gauvin, Régis M.; Nicholas, Christopher P.; Basset, Jean-Marie; Taoufik, Mostafa (Journal of Organometallic Chemistry, Elsevier BV, 2018-05-22) [Article]
    The novel complex W (=O)Np3F has been prepared by fluorination of the corresponding chloride counterpart with AgBF4. The reactivity of this complex with silica dehydroxylated at 700 °C afforded a well-defined silica supported monopodal tungsten oxo trialkyl surface species (≡SiO)W (=O)Np3. The reaction proceeds both through silanolysis of the W-F bond and opening of a siloxane bridge, with formation of a Si-F fragment, thanks to the affinity of silicon for fluoride. The resulting surface species was characterized by elemental analysis, DRIFT, solid state NMR and EXAFS spectroscopy. This material presenting fluorine on its surface shows an enhanced catalytic activity in propylene self-metathesis compared to its monopodal counterpart (≡SiO)W (=O)Np3 (prepared from W (=O)Np3Cl) suggesting that the Si-F in a close vicinity to the W decreases the electron density of the W and thus increases its reactivity towards the olefinic substrate.
  • Application of Semiempirical Methods to Transition Metal Complexes: Fast Results but Hard-to-Predict Accuracy.

    Minenkov, Yury; Sharapa, Dmitry I.; Cavallo, Luigi (Journal of Chemical Theory and Computation, American Chemical Society (ACS), 2018-05-22) [Article]
    A series of semiempirical PM6* and PM7 methods has been tested in reproducing of relative conformational energies of 27 realistic-size complexes of 16 different transition metals (TMs). An analysis of relative energies derived from single-point energy evaluations on density functional theory (DFT) optimized conformers revealed pronounced deviations between semiempirical and DFT methods indicating fundamental difference in potential energy surfaces (PES). To identify the origin of the deviation, we compared fully optimized PM7 and respective DFT conformers. For many complexes, differences in PM7 and DFT conformational energies have been confirmed often manifesting themselves in false coordination of some atoms (H, O) to TMs and chemical transformations/distortion of coordination center geometry in PM7 structures. Despite geometry optimization with fixed coordination center geometry leads to some improvements in conformational energies, the resulting accuracy is still too low to recommend explored semiempirical methods for out-of-the-box conformational search/sampling: careful testing is always needed.
  • Robust nonfullerene solar cells approaching unity external quantum efficiency enabled by suppression of geminate recombination

    Baran, Derya; Gasparini, Nicola; Wadsworth, Andrew; Tan, Ching Hong; Wehbe, Nimer; Song, Xin; Hamid, Zeinab; Zhang, Weimin; Neophytou, Marios; Kirchartz, Thomas; Brabec, Christoph J.; Durrant, James R.; McCulloch, Iain (Nature Communications, Springer Nature, 2018-05-21) [Article]
    Nonfullerene solar cells have increased their efficiencies up to 13%, yet quantum efficiencies are still limited to 80%. Here we report efficient nonfullerene solar cells with quantum efficiencies approaching unity. This is achieved with overlapping absorption bands of donor and acceptor that increases the photon absorption strength in the range from about 570 to 700 nm, thus, almost all incident photons are absorbed in the active layer. The charges generated are found to dissociate with negligible geminate recombination losses resulting in a short-circuit current density of 20 mA cm-2 along with open-circuit voltages >1 V, which is remarkable for a 1.6 eV bandgap system. Most importantly, the unique nano-morphology of the donor:acceptor blend results in a substantially improved stability under illumination. Understanding the efficient charge separation in nonfullerene acceptors can pave the way to robust and recombination-free organic solar cells.
  • Nanosheets of Nonlayered Aluminum Metal-Organic Frameworks through a Surfactant-Assisted Method

    Pustovarenko, Alexey; Goesten, Maarten G.; Sachdeva, Sumit; Shan, Meixia; Amghouz, Zakariae; Belmabkhout, Youssef; Dikhtiarenko, Alla; Rodenas, Tania; Keskin, Damla; Voets, Ilja K.; Weckhuysen, Bert M.; Eddaoudi, Mohamed; de Smet, Louis C. P. M.; Sudhölter, Ernst J. R.; Kapteijn, Freek; Seoane, Beatriz; Gascon, Jorge (Advanced Materials, Wiley, 2018-05-18) [Article]
    During the last decade, the synthesis and application of metal-organic framework (MOF) nanosheets has received growing interest, showing unique performances for different technological applications. Despite the potential of this type of nanolamellar materials, the synthetic routes developed so far are restricted to MOFs possessing layered structures, limiting further development in this field. Here, a bottom-up surfactant-assisted synthetic approach is presented for the fabrication of nanosheets of various nonlayered MOFs, broadening the scope of MOF nanosheets application. Surfactant-assisted preorganization of the metallic precursor prior to MOF synthesis enables the manufacture of nonlayered Al-containing MOF lamellae. These MOF nanosheets are shown to exhibit a superior performance over other crystal morphologies for both chemical sensing and gas separation. As revealed by electron microscopy and diffraction, this superior performance arises from the shorter diffusion pathway in the MOF nanosheets, whose 1D channels are oriented along the shortest particle dimension.
  • Morphology control of anatase TiO2 for well-defined surface chemistry

    Jeantelot, Gabriel; Ould-Chikh, Samy; Sofack-Kreutzer, Julien; Abou-Hamad, Edy; Anjum, Dalaver H.; Lopatin, Sergei; Harb, Moussab; Cavallo, Luigi; Basset, Jean-Marie (Physical Chemistry Chemical Physics, Royal Society of Chemistry (RSC), 2018-05-16) [Article]
    A specific allotrope of titanium dioxide (anatase) was synthesized both with a standard thermodynamic morphology ({101}-anatase) and with a highly anisotropic morphology ({001}-anatase) dominated by the {001} facet (81%). The surface chemistry of both samples after dehydroxylation was studied by 1H NMR and FT-IR. The influence of surface fluorides on the surface chemistry was also studied by 1H NMR, FT-IR and DFT. Full attribution of the IR spectra of anatase with dominant {001} facets could be provided based on experimental data and further confirmed by DFT. Our results showed that chemisorbed H2O molecules are still present on anatase after dehydroxylation at 350 °C, and that the type of surface hydroxyls present on the {001} facet is dependent on the presence of fluorides. They also provided general insight into the nature of the surface species on both fluorinated and fluorine-free anatase. The use of vanadium oxychloride (VOCl3) allowed the determination of the accessibility of the various OH groups spectroscopically observed.
  • On the Peculiar Molecular Shape and Size Dependence of the Dynamics of Fluids confined in a Small-Pore Metal-Organic Framework

    Skarmoutsos, Ioannis; Eddaoudi, Mohamed; Maurin, Guillaume (The Journal of Physical Chemistry Letters, American Chemical Society (ACS), 2018-05-15) [Article]
    Force field based-Molecular dynamics simulations were deployed to systematically explore the dynamics of confined molecules of different shapes and sizes, i.e. linear (CO2 and N2) and spherical (CH4) fluids, in a model small pore system, i.e. the Metal-Organic Framework SIFSIX-2-Cu-i. These computations unveil an unprecedented molecular symmetry dependence of the translational and rotational dynamics of fluids confined in channel-like nanoporous materials. In particular this peculiar behaviour is reflected by the extremely slow decay of the Legendre reorientational correlation functions of even-parity order for the linear fluids which is associated to jump-like orientation flips, while the spherical fluid shows a very fast decay taking place in a sub-picosecond time scale. Such a fundamental understanding is relevant to diverse disciplines such as in chemistry, physics, biology and materials science where diatomic or polyatomic molecules of different shapes/sizes diffuse through nanopores.
  • Impact of Pore–Walls Ligand Assembly on the Biodegradation of Mesoporous Organosilica Nanoparticles for Controlled Drug Delivery

    Omar, Haneen; Moosa, Basem; Alamoudi, Kholod; Anjum, Dalaver H.; Emwas, Abdul-Hamid M.; El Tall, Omar; Vu, Binh; Tamanoi, Fuyu; AlMalik, Abdulaziz; Khashab, Niveen M. (ACS Omega, American Chemical Society (ACS), 2018-05-14) [Article]
    Porous materials with molecular-scale ordering have attracted major attention mainly because of the possibility to engineer their pores for selective applications. Periodic mesoporous organosilica is a class of hybrid materials where self-assembly of the organic linkers provides a crystal-like pore wall. However, unlike metal coordination, specific geometries cannot be predicted because of the competitive and dynamic nature of noncovalent interactions. Herein, we study the influence of competing noncovalent interactions in the pore walls on the biodegradation of organosilica frameworks for drug delivery application. These results support the importance of studying self-assembly patterns in hybrid frameworks to better engineer the next generation of dynamic or “soft” porous materials.
  • Transition-Metal-Catalyzed Decarbonylative Coupling Reactions: Concepts, Classifications, and Applications

    Guo, Lin; Rueping, Magnus (Chemistry - A European Journal, Wiley, 2018-05-14) [Article]
    Transition metal-catalyzed decarbonylative coupling reactions have emerged as a powerful alternative to conventional cross-coupling protocols due to the advantages associated with the use of carbonyl-containing functionalities as coupling electrophiles instead of commonly used organohalides or sulfates. A wide variety of novel transformations based on this concept have been successfully achieved, including decarbonylative carbon–carbon and carbon–heteroatom bond forming reactions. In this Review, we summarize the recent progress in this field and present a comprehensive overview of metal-catalyzed decarbonylative coupling reactions with carbonyl derivatives.
  • Cross-Coupling of Amides with Alkylboranes via Nickel-Catalyzed C–N Bond Cleavage

    Liu, Xiangqian; Hsiao, Chien-Chi; Guo, Lin; Rueping, Magnus (Organic Letters, American Chemical Society (ACS), 2018-05-09) [Article]
    A protocol for the nickel-catalyzed alkylation of amides was established. The use of alkylboranes as nucleophilic partners allowed the use of mild reaction conditions and compatibility of various functional groups with respect to both coupling partners. The catalytic alkylation proceeded selectively at the amides in the presence of other functional groups as well as other carboxylic acid derived moieties.
  • Dimerization of Terminal Aryl Alkynes Catalyzed by Iron(II) Amine-Pyrazolyl Tripodal Complexes with E/Z Selectivity Controlled by tert-Butoxide

    Xue, Fei; Song, Xiaolu; Lin, Ting Ting; Munkerup, Kristin; Albawardi, Saad Fahad; Huang, Kuo-Wei; Hor, T. S. Andy; Zhao, Jin (ACS Omega, American Chemical Society (ACS), 2018-05-09) [Article]
    The catalytic activity of iron(II) complexes with functionalized amine-pyrazolyl tripodal ligands toward dimerization of terminal alkynes in the presence a base (KOtBu or NaOtBu) has been studied. An unusual E/Z selectivity of the reaction determined by tert-butoxide was observed.
  • Manganese Catalyzed Regioselective C–H Alkylation: Experiment and Computation

    Wang, Chengming; Maity, Bholanath; Cavallo, Luigi; Rueping, Magnus (Organic Letters, American Chemical Society (ACS), 2018-05-08) [Article]
    A new efficient manganese-catalyzed selective C2-alkylation of indoles via carbenoid insertion has been achieved. The newly developed C-H functionalization protocol provides access to diverse products and shows good functional group tolerance. Mechanistic and computational studies support the formation of a Mn(CO)3 acetate complex as the catalytically active species.
  • Constructing Bridges between Computational Tools in Heterogeneous and Homogeneous Catalysis

    Falivene, Laura; Kozlov, Sergey M.; Cavallo, Luigi (ACS Catalysis, American Chemical Society (ACS), 2018-05-08) [Article]
    Better catalysts are needed to address numerous challenges faced by humanity. In this perspective, we review concepts and tools in theoretical and computational chemistry that can help to accelerate the rational design of homogeneous and heterogeneous catalysts. In particular, we focus on the following three topics: 1) identification of key intermediates and transition states in a reaction using the energetic span model, 2) disentanglement of factors influencing the relative stability of the key species using energy decomposition analysis and the activation strain model, and 3) discovery of new catalysts using volcano relationships. To facilitate wider use of these techniques across different areas, we illustrate their potentials and pitfalls when applied to the study of homogeneous and heterogeneous catalysts.
  • Multiple Hydrogen-Bond Activation in Asymmetric Brønsted Acid Catalysis

    Liao, Hsuan-Hung; Hsiao, Chien-Chi; Atodiresei, Iuliana; Rueping, Magnus (Chemistry - A European Journal, Wiley, 2018-05-03) [Article]
    An efficient protocol for the asymmetric synthesis of chiral tetrahydroquinolines bearing multiple stereogenic centers by means of asymmetric Brønsted acid catalysis was developed. A chiral 1,1′-spirobiindane-7,7′-diol (SPINOL)-based N-triflylphosphoramide (NTPA) proved to be an effective Brønsted acid catalyst for the in situ generation of aza-ortho-quinone methides (aza-o-QMs) and their subsequent cycloaddition reaction with unactivated alkenes to provide the products with excellent diastereo- and enantioselectivities. In addition, DFT calculations provided insight into the activation mode and nature of the interactions between the N-triflylphosphoramide catalyst and the generated aza-o-QMs.
  • Exploring Trianglamine Derivatives and Trianglamine Coordination Complexes as Porous Organic Materials

    Eziashi, Magdalene (2018-05) [Thesis]
    Advisor: Khashab, Niveen M.
    Committee members: Eddaoudi, Mohamed; Pain, Arnab
    Trianglamines are triangular chiral macrocycles that were first synthesized by Gawronski’s group in Poland in the year 2000.1 Despite their unique properties; triangular pore shape, chirality, symmetric structure and tunable pore size, they are still a poorly researched class of macrocycles today. Trianglamines have yet a role to play as porous organic molecules for separation processes, as macrocyclic precursors to build increasingly complex supramolecular assemblies and as building blocks for caged porous organic structures. The aim of the Thesis work is to explore trianglamine, its derivatives, and assemblies as viable porous organic molecules for potential gas capture and separation.
  • Hyperbranched Polyethylenebased Macromolecular Architectures: Synthesis, Characterization, and Selfassembly

    Al-Sulami, Ahlam (2018-05) [Dissertation]
    Advisor: Hadjichristidis, Nikolaos
    Committee members: Nunes, Suzana Pereira; Rodionov, Valentin; Avgeropoulos, Apostolos
    "Chain walking” catalytic polymerization CWCP is a powerful tool for the one-pot synthesis of a unique class of hyperbranched polyethylene HBPE-based macromolecules with a controllable molecular weight, topology, and composition. This dissertation focuses on new synthetic routes to prepare HBPE-based macromolecular architectures by combining the CWCP technique with ring opening polymerization ROP, atom–transfer radical polymerization ATRP, and “click” chemistry. Taking advantage of end-functionalized HBPE, and a new ethynyl-soketal star-shape agent, we were able to synthesize different types of the HBPE-based architectures including hyperbranched-on-hyperbranched core-shell nanostructure, and miktoarm-star-HBPE-based block copolymers. The first part of the dissertation provides a general introduction to the synthesis of polyethylene types with controllable structures. Well-defined polyethylene with different macromolecule architectures were synthesized either for academic or industrial purposes. In the second part, the HBPE with different topologies was synthesized by CWCP, using a α-diimine Pd (II) catalyst. The effect of the temperature and pressure on the catalyst activity and polymer properties, including branch content, molecular weight, distribution, and thermal properties were studied. Two series of samples were synthesized: a) serial samples (A) under pressures of 1, 5, and 27 atm at 5˚C, and b) serial samples (B) at temperatures of 5, 15, and 35 ˚C under 5 atm. Proton nuclear magnetic resonance spectroscopy, 1H NMR, and gel permeation chromatography, GPC, analysis were used to calculate the branching content, molecular weight, and distribution, whereas differential scanning calorimetry, DSC, was used to record the melting and glass transition temperatures as well as the degree of the crystallinity. Well-defined HBPE-based core diblock copolymers with predictable amphiphilic properties are studied in the third part of the project. Hyperbranched polyethylene-b-poly(N-isopropylacrylamide), HBPE-b-PNIPAM, and hyperbranched polyethylene-b-poly(solketal acrylate), HBPE-b-PSA, were successfully synthesized by combining CWCP and ATRP. The synthetic methodology includes the following steps; a) synthesis of multifunction hyperbranched polyethylene initiators HBPE-MI by direct copolymerization of ethylene with 2-(2-bromoisobutyryloxy)ethyl acrylate BIEA in the presence of a α-diimine Pd(II) catalyst, and b) HBPE-MI with α-bromoester groups used as initiation sites for ATRP. Proton nuclear magnetic resonance spectroscopy, 1H NMR, gel permeation chromatography,GPC, and Fourier transform infrared, FT-IR, spectroscopy, were used for determining the molecular and composition structures. Also, differential scanning calorimetry, DSC, and thermogravimetric analysis, TGA, were used to record the melting temperature and to study the thermal stability, respectively. In the fourth part, a well-defined 3-miktoarm star copolymer 3μ-HBPE(PCL)2 (HBPE: hyperbranched polyethylene, PCL: poly(ε-caprolactone) was synthesized by combining CWCP, ring opening polymerization, ROP, and “click” chemistry. The synthetic methodology includes the following steps: a) synthesis of azido-functionalized hyperbranched polyethylene HBPE-N3 by CWCP of ethylene with the α-diimine Pd(II) catalyst, followed by quenching with an excess of 4-vinylbenzyl chloride and transformation of –Cl to the azido group with sodium azide, b) synthesis of in-chain ethynyl-functionalized poly(ε-caprolactone), (PCL)2-C≡CH by ROP of ε-CL with ethynylfunctionalized solketal [3-(prop-2-yn-1-yloxy) propane-1,2-diol] as a bifunctional initiator, in the presence of P2-t-Bu phosphazene super base, and c) “clicking” HBPE-N3 and (PCL)2-C≡CH using the copper(I)-catalyzed alkyne–azide cycloaddition CuAAC. Proton nuclear magnetic resonance spectroscopy, 1H NMR, gel permeation chromatography, GPC, and Fourier transform infrared, FT-IR, spectroscopy, were used to determine the molecular and composition structures. Also, the differential scanning calorimetry, DSC, was used to record the melting point temperature. The fifth part illustrates the self-assembly behavior of the HBPE-based block copolymers of poly(N-isopropylacrylamide), NIPAM, and poly(ε-caprolactone), PCL, at room temperature in water and a petroleum ether-selective solvent for NIPAM and PCL respectively. The synthesized copolymers HBPE-b-NIPAM and 3μ-HBPE(PCL)2 revealed either core-shell nanostructure in vesicles or worms and worm-likes branches, as confirmed by combining the analysis of dynamic light scattering, DLS, transmission electron microscopy, TEM, and atomic force spectroscopy, AFM. All the findings presented in this dissertation emphasize the utility of "living" CWCP to synthesize end-functionalized HBPE, and new star-linkage HBPE-based complex architectures. The summary and future works concerning predictable properties and applications are discussed in the sixth part.
  • Catalytic amino acid production from biomass-derived intermediates

    Deng, Weiping; Wang, Yunzhu; Zhang, Sui; Gupta, Krishna M.; Hülsey, Max J.; Asakura, Hiroyuki; Liu, Lingmei; Han, Yu; Karp, Eric M.; Beckham, Gregg T.; Dyson, Paul J.; Jiang, Jianwen; Tanaka, Tsunehiro; Wang, Ye; Yan, Ning (Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, 2018-04-30) [Article]
    Amino acids are the building blocks for protein biosynthesis and find use in myriad industrial applications including in food for humans, in animal feed, and as precursors for bio-based plastics, among others. However, the development of efficient chemical methods to convert abundant and renewable feedstocks into amino acids has been largely unsuccessful to date. To that end, here we report a heterogeneous catalyst that directly transforms lignocellulosic biomass-derived α-hydroxyl acids into α-amino acids, including alanine, leucine, valine, aspartic acid, and phenylalanine in high yields. The reaction follows a dehydrogenation-reductive amination pathway, with dehydrogenation as the rate-determining step. Ruthenium nanoparticles supported on carbon nanotubes (Ru/CNT) exhibit exceptional efficiency compared with catalysts based on other metals, due to the unique, reversible enhancement effect of NH3 on Ru in dehydrogenation. Based on the catalytic system, a two-step chemical process was designed to convert glucose into alanine in 43% yield, comparable with the well-established microbial cultivation process, and therefore, the present strategy enables a route for the production of amino acids from renewable feedstocks. Moreover, a conceptual process design employing membrane distillation to facilitate product purification is proposed and validated. Overall, this study offers a rapid and potentially more efficient chemical method to produce amino acids from woody biomass components.
  • Critical review of the molecular design progress in non-fullerene electron acceptors towards commercially viable organic solar cells

    Wadsworth, Andrew; Moser, Maximilian; Marks, Adam; Little, Mark S.; Gasparini, Nicola; Brabec, Christoph J.; Baran, Derya; McCulloch, Iain (Chemical Society Reviews, Royal Society of Chemistry (RSC), 2018-04-26) [Article]
    Fullerenes have formed an integral part of high performance organic solar cells over the last 20 years, however their inherent limitations in terms of synthetic flexibility, cost and stability have acted as a motivation to develop replacements; the so-called non-fullerene electron acceptors. A rapid evolution of such materials has taken place over the last few years, yielding a number of promising candidates that can exceed the device performance of fullerenes and provide opportunities to improve upon the stability and processability of organic solar cells. In this review we explore the structure-property relationships of a library of non-fullerene acceptors, highlighting the important chemical modifications that have led to progress in the field and provide an outlook for future innovations in electron acceptors for use in organic photovoltaics.
  • Poly(3-hydroxybutyrate) production in an integrated electromicrobial setup: Investigation under stress-inducing conditions

    Al Rowaihi, Israa Salem; Paillier, Alexis; Rasul, Shahid; Karan, Ram; Grötzinger, Stefan Wolfgang; Takanabe, Kazuhiro; Eppinger, Jörg (PLOS ONE, Public Library of Science (PLoS), 2018-04-26) [Article]
    Poly(3-hydroxybutyrate) (PHB), a biodegradable polymer, can be produced by different microorganisms. The PHB belongs to the family of polyhydroxyalkanoate (PHA) that mostly accumulates as a granule in the cytoplasm of microorganisms to store carbon and energy. In this study, we established an integrated one-pot electromicrobial setup in which carbon dioxide is reduced to formate electrochemically, followed by sequential microbial conversion into PHB, using the two model strains, Methylobacterium extorquens AM1 and Cupriavidus necator H16. This setup allows to investigate the influence of different stress conditions, such as coexisting electrolysis, relatively high salinity, nutrient limitation, and starvation, on the production of PHB. The overall PHB production efficiency was analyzed in reasonably short reaction cycles typically as short as 8 h. As a result, the PHB formation was detected with C. necator H16 as a biocatalyst only when the electrolysis was operated in the same solution. The specificity of the source of PHB production is discussed, such as salinity, electricity, concurrent hydrogen production, and the possible involvement of reactive oxygen species (ROS).

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