@article{UgwujaAdelowoOgunlajaetal.2019, author = {Ugwuja, Chidinma G. and Adelowo, Olawale O. and Ogunlaja, Aemere and Omorogie, Martins O. and Olukanni, Olumide D. and Ikhimiukor, Odion O. and Iermak, Ievgeniia and Kolawole, Gabriel A. and G{\"u}nter, Christina and Taubert, Andreas and Bodede, Olusola and Moodley, Roshila and Inada, Natalia M. and Camargo, Andrea S.S. de and Unuabonah, Emmanuel Iyayi}, title = {Visible-Light-Mediated Photodynamic Water Disinfection @ Bimetallic-Doped Hybrid Clay Nanocomposites}, series = {ACS applied materials \& interfaces}, volume = {11}, journal = {ACS applied materials \& interfaces}, number = {28}, publisher = {American Chemical Society}, address = {Washington, DC}, issn = {1944-8244}, doi = {10.1021/acsami.9b01212}, pages = {25483 -- 25494}, year = {2019}, abstract = {This study reports a new class of photocatalytic hybrid clay nanocomposites prepared from low-cost sources (kaolinite clay and Carica papaya seeds) doped with Zn and Cu salts via a solvothermal process. X-ray diffraction analysis suggests that Cu-doping and Cu/Zn-doping introduce new phases into the crystalline structure of Kaolinite clay, which is linked to the reduced band gap of kaolinite from typically between 4.9 and 8.2 eV to 2.69 eV for Cu-doped and 1.5 eV for Cu/Zn hybrid clay nanocomposites (Nisar, J.; Arhammar, C.; Jamstorp, E.; Ahuja, R. Phys. Rev. B 2011, 84, 075120). In the presence of solar light irradiation, Cu- and Cu/Zn-doped nanocomposites facilitate the electron hole pair separation. This promotes the generation of singlet oxygen which in turn improves the water disinfection efficiencies of these novel nanocomposite materials. The nanocomposite materials were further characterized using high-resolution scanning electron microscopy, fluorimetry, therrnogravimetric analysis, and Raman spectroscopy. The breakthrough times of the nanocomposites for a fixed bed mode of disinfection of water contaminated with 2.32 x 10(7) cfu/mL E. coli ATCC 25922 under solar light irradiation are 25 h for Zn-doped, 30 h for Cu-doped, and 35 h for Cu/Zn-doped nanocomposites. In the presence of multidrug and multimetal resistant strains of E. coli, the breakthrough time decreases significantly. Zn-only doped nanocomposites are not photocatalytically active. In the absence of light, the nanocomposites are still effective in decontaminating water, although less efficient than under solar light irradiation. Electrostatic interaction, metal toxicity, and release of singlet oxygen (only in the Cu-doped and Cu/Zn-doped nanocomposites) are the three disinfection mechanisms by which these nanocomposites disinfect water. A regrowth study indicates the absence of any living E. coli cells in treated water even after 4 days. These data and the long hydraulic times (under gravity) exhibited by these nanocomposites during photodisinfection of water indicate an unusually high potential of these nanocomposites as efficient, affordable, and sustainable point-of-use systems for the disinfection of water in developing countries.}, language = {en} } @article{PereiraZehbeGuenteretal.2018, author = {Pereira, Rui F. P. and Zehbe, Kerstin and G{\"u}nter, Christina and dos Santos, Tiago and Nunes, Silvia C. and Almeida Paz, Filipe A. and Silva, Maria M. and Granja, Pedro L. and Taubert, Andreas and de Zea Bermudez, Ver{\´o}nica}, title = {Ionic liquid-assisted synthesis of mesoporous silk fibroin/silica hybrids for biomedical applications}, series = {ACS Omega}, volume = {3}, journal = {ACS Omega}, number = {9}, publisher = {American Chemical Society}, address = {Washington}, issn = {2470-1343}, doi = {10.1021/acsomega.8b02051}, pages = {10811 -- 10822}, year = {2018}, abstract = {New mesoporous silk fibroin (SF)/silica hybrids were processed via a one-pot soft and energy-efficient sol-gel chemistry and self-assembly from a silica precursor, an acidic or basic catalyst, and the ionic liquid 1-butyl-3-methylimidazolium chloride, acting as both solvent and mesoporosity-inducer. The as-prepared materials were obtained as slightly transparent-opaque, amorphous monoliths, easily transformed into powders, and stable up to ca. 300 degrees C. Structural data suggest the formation of a hexagonal mesostructure with low range order and apparent surface areas, pore volumes, and pore radii of 205-263 m(2) g(-1), 0.16-0.19 cm(3) g(-1), and 1.2-1.6 nm, respectively. In all samples, the dominating conformation of the SF chains is the beta-sheet. Cytotoxicity/bioactivity resazurin assays and fluorescence microscopy demonstrate the high viability of MC3T3 pre-osteoblasts to indirect (>= 99 +/- 9\%) and direct (78 +/- 2 to 99 +/- 13\%) contact with the SF/silica materials. Considering their properties and further improvements, these systems are promising candidates to be explored in bone tissue engineering. They also offer excellent prospects as electrolytes for solid-state electrochemical devices, in particular for fuel cells.}, language = {en} } @article{KimHeyneAbouserieetal.2018, author = {Kim, Yohan and Heyne, Benjamin and Abouserie, Ahed and Pries, Christopher and Ippen, Christian and G{\"u}nter, Christina and Taubert, Andreas and Wedel, Armin}, title = {CuS nanoplates from ionic liquid precursors-Application in organic photovoltaic cells}, series = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr}, volume = {148}, journal = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr}, number = {19}, publisher = {American Institute of Physics}, address = {Melville}, issn = {0021-9606}, doi = {10.1063/1.4991622}, pages = {10}, year = {2018}, abstract = {Hexagonal p-type semiconductor CuS nanoplates were synthesized via a hot injection method from bis(trimethylsilyl) sulfide and the ionic liquid precursor bis(N-dodecylpyridinium) tetrachloridocuprate( II). The particles have a broad size distribution with diameters between 30 and 680 nm and well-developed crystal habits. The nanoplates were successfully incorporated into organic photovoltaic (OPV) cells as hole conduction materials. The power conversion efficiency of OPV cells fabricated with the nanoplates is 16\% higher than that of a control device fabricated without the nanoplates. (C) 2018 Author(s).}, language = {en} } @article{BlockGuenterRodriguesetal.2021, author = {Block, Inga and G{\"u}nter, Christina and Rodrigues, Alysson Duarte and Paasch, Silvia and Hesemann, Peter and Taubert, Andreas}, title = {Carbon Adsorbents from Spent Coffee for Removal of Methylene Blue and Methyl Orange from Water}, series = {Materials}, volume = {14}, journal = {Materials}, number = {14}, publisher = {MDPI}, address = {Basel}, issn = {1996-1944}, doi = {10.3390/ma14143996}, pages = {18}, year = {2021}, abstract = {Activated carbons (ACs) were prepared from dried spent coffee (SCD), a biological waste product, to produce adsorbents for methylene blue (MB) and methyl orange (MO) from aqueous solution. Pre-pyrolysis activation of SCD was achieved via treatment of the SCD with aqueous sodium hydroxide solutions at 90 °C. Pyrolysis of the pretreated SCD at 500 °C for 1 h produced powders with typical characteristics of AC suitable and effective for dye adsorption. As an alternative to the rather harsh base treatment, calcium carbonate powder, a very common and abundant resource, was also studied as an activator. Mixtures of SCD and CaCO3 (1:1 w/w) yielded effective ACs for MO and MB removal upon pyrolysis needing only small amounts of AC to clear the solutions. A selectivity of the adsorption process toward anionic (MO) or cationic (MB) dyes was not observed.}, language = {en} } @article{KruegerSchwarzeBaumannetal.2018, author = {Kr{\"u}ger, Stefanie and Schwarze, Michael and Baumann, Otto and G{\"u}nter, Christina and Bruns, Michael and K{\"u}bel, Christian and Szabo, Dorothee Vinga and Meinusch, Rafael and Bermudez, Veronica de Zea and Taubert, Andreas}, title = {Bombyx mori silk/titania/gold hybrid materials for photocatalytic water splitting}, series = {Beilstein journal of nanotechnology}, volume = {9}, journal = {Beilstein journal of nanotechnology}, publisher = {Beilstein-Institut zur F{\"o}rderung der Chemischen Wissenschaften}, address = {Frankfurt, Main}, issn = {2190-4286}, doi = {10.3762/bjnano.9.21}, pages = {187 -- 204}, year = {2018}, abstract = {The synthesis, structure, and photocatalytic water splitting performance of two new titania (TiO2)/gold(Au)/Bombyx mori silk hybrid materials are reported. All materials are monoliths with diameters of up to ca. 4.5 cm. The materials are macroscopically homogeneous and porous with surface areas between 170 and 210 m(2)/g. The diameter of the TiO2 nanoparticles (NPs) - mainly anatase with a minor fraction of brookite - and the Au NPs are on the order of 5 and 7-18 nm, respectively. Addition of poly(ethylene oxide) to the reaction mixture enables pore size tuning, thus providing access to different materials with different photocatalytic activities. Water splitting experiments using a sunlight simulator and a Xe lamp show that the new hybrid materials are effective water splitting catalysts and produce up to 30 mmol of hydrogen per 24 h. Overall the article demonstrates that the combination of a renewable and robust scaffold such as B. mori silk with a photoactive material provides a promising approach to new monolithic photocatalysts that can easily be recycled and show great potential for application in lightweight devices for green fuel production.}, language = {en} } @article{BalischewskiBehrensZehbeetal.2020, author = {Balischewski, Christian and Behrens, Karsten and Zehbe, Kerstin and G{\"u}nter, Christina and Mies, Stefan and Sperlich, Eric and Kelling, Alexandra and Taubert, Andreas}, title = {Ionic liquids with more than one metal}, series = {Chemistry - a European journal}, volume = {26}, journal = {Chemistry - a European journal}, number = {72}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0947-6539}, doi = {10.1002/chem.202003097}, pages = {17504 -- 17513}, year = {2020}, abstract = {Thirteen N-butylpyridinium salts, including three monometallic [C4Py](2)[MCl4], nine bimetallic [C4Py](2)[(M1-xMxCl4)-M-a-Cl-b] and one trimetallic compound [C4Py](2)[(M1-y-zMyMz (c) Cl4)-M-a-M-b] (M=Co, Cu, Mn; x=0.25, 0.50 or 0.75 and y=z=0.33), were synthesized and their structure and thermal and electrochemical properties were studied. All compounds are ionic liquids (ILs) with melting points between 69 and 93 degrees C. X-ray diffraction proves that all ILs are isostructural. The conductivity at room temperature is between 10(-4) and 10(-8) S cm(-1). Some Cu-based ILs reach conductivities of 10(-2) S cm(-1), which is, however, probably due to IL dec. This correlates with the optical bandgap measurements indicating the formation of large bandgap semiconductors. At elevated temperatures approaching the melting points, the conductivities reach up to 1.47x10(-1) S cm(-1) at 70 degrees C. The electrochemical stability windows of the ILs are between 2.5 and 3.0 V.}, language = {en} } @article{SchneiderGuenterTaubert2018, author = {Schneider, Matthias and G{\"u}nter, Christina and Taubert, Andreas}, title = {Co-deposition of a hydrogel/calcium phosphate hybrid layer on 3D printed poly(lactic acid) scaffolds via dip coating}, series = {Polymers}, volume = {10}, journal = {Polymers}, number = {3}, publisher = {MDPI}, address = {Basel}, issn = {2073-4360}, doi = {10.3390/polym10030275}, pages = {19}, year = {2018}, abstract = {The article describes the surface modification of 3D printed poly(lactic acid) (PLA) scaffolds with calcium phosphate (CP)/gelatin and CP/chitosan hybrid coating layers. The presence of gelatin or chitosan significantly enhances CP co-deposition and adhesion of the mineral layer on the PLA scaffolds. The hydrogel/CP coating layers are fairly thick and the mineral is a mixture of brushite, octacalcium phosphate, and hydroxyapatite. Mineral formation is uniform throughout the printed architectures and all steps (printing, hydrogel deposition, and mineralization) are in principle amenable to automatization. Overall, the process reported here therefore has a high application potential for the controlled synthesis of biomimetic coatings on polymeric biomaterials.}, language = {en} } @article{BehrensBalischewskiSperlichetal.2022, author = {Behrens, Karsten and Balischewski, Christian and Sperlich, Eric and Menski, Antonia Isabell and Balderas-Valadez, Ruth Fabiola and Pacholski, Claudia and G{\"u}nter, Christina and Lubahn, Susanne and Kelling, Alexandra and Taubert, Andreas}, title = {Mixed chloridometallate(ii) ionic liquids with tunable color and optical response for potential ammonia sensors}, series = {RSC Advances}, volume = {12}, journal = {RSC Advances}, publisher = {RSC}, address = {London}, issn = {2046-2069}, doi = {10.1039/d2ra05581c}, pages = {35072 -- 35082}, year = {2022}, abstract = {Eight d-metal-containing N-butylpyridinium ionic liquids (ILs) with the nominal composition (C4Py)2[Ni0.5M0.5Cl4] or (C4Py)2[Zn0.5M0.5Cl4] (M = Cu, Co, Mn, Ni, Zn; C4Py = N-butylpyridinium) were synthesized, characterized, and investigated for their optical properties. Single crystal and powder X-ray analysis shows that the compounds are isostructural to existing examples based on other d-metal ions. Inductively coupled plasma optical emission spectroscopy measurements confirm that the metal/metal ratio is around 50 : 50. UV-Vis spectroscopy shows that the optical absorption can be tuned by selection of the constituent metals. Moreover, the compounds can act as an optical sensor for the detection of gases such as ammonia as demonstrated via a simple prototype setup.}, language = {en} } @article{BalischewskiBhattacharyyaSperlichetal.2022, author = {Balischewski, Christian and Bhattacharyya, Biswajit and Sperlich, Eric and G{\"u}nter, Christina and Beqiraj, Alkit and Klamroth, Tillmann and Behrens, Karsten and Mies, Stefan and Kelling, Alexandra and Lubahn, Susanne and Holtzheimer, Lea and Nitschke, Anne and Taubert, Andreas}, title = {Tetrahalidometallate(II) ionic liquids with more than one metal}, series = {Chemistry - a European journal}, volume = {28}, journal = {Chemistry - a European journal}, number = {64}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1521-3765}, doi = {10.1002/chem.202201068}, pages = {13}, year = {2022}, abstract = {Fifteen N-butylpyridinium salts - five monometallic [C4Py](2)[MBr4] and ten bimetallic [C4Py](2)[(M0.5M0.5Br4)-M-a-Br-b] (M=Co, Cu, Mn, Ni, Zn) - were synthesized, and their structures and thermal and electrochemical properties were studied. All the compounds are ionic liquids (ILs) with melting points between 64 and 101 degrees C. Powder and single-crystal X-ray diffraction show that all ILs are isostructural. The electrochemical stability windows of the ILs are between 2 and 3 V. The conductivities at room temperature are between 10(-5) and 10(-6) S cm(-1). At elevated temperatures, the conductivities reach up to 10(-4) S cm(-1) at 70 degrees C. The structures and properties of the current bromide-based ILs were also compared with those of previous examples using chloride ligands, which illustrated differences and similarities between the two groups of ILs.}, language = {en} } @article{MaiBoyeYuanetal.2015, author = {Mai, Tobias and Boye, Susanne and Yuan, Jiayin and V{\"o}lkel, Antje and Gr{\"a}wert, Marlies and G{\"u}nter, Christina and Lederer, Albena and Taubert, Andreas}, title = {Poly(ethylene oxide)-based block copolymers with very high molecular weights for biomimetic calcium phosphate mineralization}, series = {RSC Advances : an international journal to further the chemical sciences}, journal = {RSC Advances : an international journal to further the chemical sciences}, number = {5}, publisher = {RSC Publishing}, address = {London}, issn = {2046-2069}, doi = {10.1039/c5ra20035k}, pages = {103494 -- 103505}, year = {2015}, abstract = {The present article is among the first reports on the effects of poly(ampholyte)s and poly(betaine)s on the biomimetic formation of calcium phosphate. We have synthesized a series of di- and triblock copolymers based on a non-ionic poly(ethylene oxide) block and several charged methacrylate monomers, 2-(trimethylammonium)ethyl methacrylate chloride, 2-((3-cyanopropyl)-dimethylammonium)ethyl methacrylate chloride, 3-sulfopropyl methacrylate potassium salt, and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide. The resulting copolymers are either positively charged, ampholytic, or betaine block copolymers. All the polymers have very high molecular weights of over 106 g mol-1. All polymers are water-soluble and show a strong effect on the precipitation and dissolution of calcium phosphate. The strongest effects are observed with triblock copolymers based on a large poly(ethylene oxide) middle block (nominal Mn = 100 000 g mol-1). Surprisingly, the data show that there is a need for positive charges in the polymers to exert tight control over mineralization and dissolution, but that the exact position of the charge in the polymer is of minor importance for both calcium phosphate precipitation and dissolution.}, language = {en} }