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- ItemSynthesis and crystal structure of a one-dimensional chain-like strontium(II) coordination polymer built of N-methyldiethanolamine and isobutyrate ligands(Chester : International Union of Crystallography, 2021) Seiss, Maximilian; Schmitz, Sebastian; Börner, Martin; Monakhov, Kirill Yu.The one-dimensional coordination polymer (I) [Sr(ib)2 (H2mda)]n (Hib = isobutyric acid, C4H8O2, and H2mda = N-methyldiethanolamine, C5H13NO2), namely, catena-poly[[(N-methyldiethanolamine-k3O, N, O')strontium(II)]-di-μ2- isobutyrato-K3O, O':O;K3O:O, O'], was prepared by the one-pot aerobic reaction of [Zr6O4 (OH)4 (ib)12 (H2O)].3Hib with Sr(NO3)2 and H2mda in the presence of MnCl2 and Et3N in acetonitrile. The use of MnCl2 is key to the isolation of I as high-quality colorless crystals in good yield. The molecular solid-state structure of I was determined by single-crystal X-ray diffraction. Compound I crystallizes in the monoclinic space group P21/c and shows a one-dimensional polymeric chain structure. Each monomeric unit of this coordination polymer consists of a central SrII ion in the NO8 coordination environment of two deprotonated ib- ligands and one fully protonated H2mda ligand. The C and O atoms of the H2mda ligand were refined as disordered over two sets of sites with site occupancies of 0.619 (3) and 0.381 (3). Compound I shows thermal stability up to 130°C in air. © 2021 International Union of Crystallography. All rights reserved.
- ItemA Diverse View of Science to Catalyse Change(Weinheim : Wiley-VCH, 2020) Urbina-Blanco, César A.; Jilani, Safia Z.; Speight, Isaiah R.; Bojdys, Michael J.; Friščić, Tomislav; Stoddart, J. Fraser; Nelson, Toby L.; Mack, James; Robinson, Renã A.S.; Waddell, Emanuel A.; Lutkenhaus, Jodie L.; Godfrey, Murrell; Abboud, Martine I.; Aderinto, Stephen O.; Aderohunmu, Damilola; Bibič, Lučka; Borges, João; Dong, Vy M.; Ferrins, Lori; Fung, Fun Man; John, Torsten; Lim, Felicia P.L.; Masters, Sarah L.; Mambwe, Dickson; Thordarson, Pall; Titirici, Maria-Magdalena; Tormet-González, Gabriela D.; Unterlass, Miriam M.; Wadle, Austin; Yam, Vivian W.-W.; Yang, Ying-WeiValuing diversity leads to scientific excellence, the progress of science and most importantly, it is simply the right thing to do. We can value diversity not only in words, but also in actions. From the structure of DNA,1 to computer science,2 and space-station batteries,3 several key scientific discoveries that enhance our lives today, were made by marginalized scientists. These three scientists, Rosalind E. Franklin, Alan M. Turing and Olga D. González-Sanabria, did not conform to the cultural expectations of how scientists should look and behave. Unfortunately, marginalized scientists are often viewed as just a resource rather than the lifeblood that constitutes science itself. We need to embrace scientists from all walks of life and corners of the globe; this will also mean that nobody is excluded from tackling the life-threatening societal challenges that lie ahead. An awareness of science policy is essential to safeguarding our future. Science policy deals with creating the framework and codes of conduct that determine how science can best serve society.4-6 Discussions around science policy are often accompanied by anecdotes of “good” and “bad” practices regarding the merits of diversity and inclusion. Excellence and truth, which flow inexorably from diversity and inclusion, are the bedrocks upon which science should influence political and economic outcomes. A vital area of science policy is to support the professional development of marginalized scientists, an objective that must be acted upon by scientific leaders and communicators...
- ItemDepth-Resolved Phase Analysis of Expanded Austenite Formed in Austenitic Stainless Steel(Basel : MDPI, 2020) Manova, Darina; Schlenz, Patrick; Gerlach, Jürgen W.; Mändl, StephanExpanded austenite γN formed after nitrogen insertion into austenitic stainless steel and CoCr alloys is known as a hard and very wear resistant phase. Nevertheless, no single composition and lattice expansion can describe this phase with nitrogen in solid solution. Using in situ X-ray diffraction (XRD) during ion beam sputtering of expanded austenite allows a detailed depth-dependent phase analysis, correlated with the nitrogen depth profiles obtained by time-of-flight secondary ion mass spectrometry (ToF-SIMS) or glow discharge optical emission spectroscopy (GDOES). Additionally, in-plane XRD measurements at selected depths were performed for strain analysis. Surprisingly, an anomalous peak splitting for the (200) expanded peak was observed for some samples during nitriding and sputter etching, indicating a layered structure only for {200} oriented grains. The strain analysis as a function of depth and orientation of scattering vector (parallel/perpendicular to the surface) is inconclusive. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
- ItemLong-Living Holes in Grey Anatase TiO2 Enable Noble-Metal-Free and Sacrificial-Agent-Free Water Splitting(Weinheim : Wiley-VCH, 2020) Liu, Ning; Mohajernia, Shiva; Nguyen, Nhat Truong; Hejazi, Seyedsina; Plass, Fabian; Kahnt, Axel; Yokosawa, Tadahiro; Osvet, Andres; Spiecker, Erdmann; Guldi, Dirk M.; Schmuki, PatrikTitanium dioxide has been the benchmark semiconductor in photocatalysis for more than 40 years. Full water splitting, that is, decomposing water into H2 and O2 in stoichiometric amounts and with an acceptable activity, still remains a challenge, even when TiO2-based photocatalysts are used in combination with noble-metal co-catalysts. The bottleneck of anatase-type TiO2 remains the water oxidation, that is, the hole transfer reaction from pristine anatase to the aqueous environment. In this work, we report that “grey” (defect engineered) anatase can provide a drastically enhanced lifetime of photogenerated holes, which, in turn, enables an efficient oxidation reaction of water to peroxide via a two-electron pathway. As a result, a Ni@grey anatase TiO2 catalyst can be constructed with an impressive performance in terms of photocatalytic splitting of neutral water into H2 and a stoichiometric amount of H2O2 without the need of any noble metals or sacrificial agents. The finding of long hole lifetimes in grey anatase opens up a wide spectrum of further photocatalytic applications of this material. © 2020 The Authors. Published by Wiley-VCH GmbH
- ItemData on single pulse fs laser induced submicron bubbles in the subsurface region of soda-lime glass(Amsterdam [u.a.] : Elsevier, 2020) Lai, Shengying; Ehrhardt, Martin; Lorenz, Pierre; Lu, Jian; Han, Bing; Zimmer, KlausSubmicron bubble formation in the subsurface range of soda-lime glass is investigated. The bubbles are induced by single femtosecond laser pulse irradiation with the wavelength of λ = 775 nm, the pulse duration of tp = 150 fs and the laser beam diameter of ∼12 μm. The data shows the changes of the morphologies of the soda-lime glass after laser irradiation with different pulse energy. Moreover, the data shows the detail of the cross-section view of the bubble during the Focused ion beam (FIB) cutting. It is found that the bubbles can be formed in a rather narrow pulse energy range with the bubbles in the size of 300 nm ∼3 μm which is much smaller than the laser beam diameter. Data presented in this article are related to the research article “Submicron bubbles/voids formation in the subsurface region of soda-lime glass by single pulse fs laser-induced spallation” [1]. © 2020
- ItemMixed-ligand lanthanide complexes supported by ditopic bis(imino-methyl)-phenol/calix[4]arene macrocycles: synthesis, structures, and luminescence properties of [Ln2(L2)(MeOH)2] (Ln = La, Eu, Tb, Yb)(London : Soc., 2020) Ullmann, Steve; Hahn, Peter; Mini, Parvathy; Tuck, Kellie L.; Kahnt, Axel; Abel, Bernd; Gutierrez Suburu, Matias E.; Strassert, Cristian A.; Kersting, BertholdThe lanthanide binding ability of a macrocyclic ligand H6L2 comprising two bis(iminomethyl)phenol and two calix[4]arene units has been studied. H6L2 is a ditopic ligand which provides dinuclear neutral complexes of composition [Ln2(L2)(MeOH)2] (Ln = La (1), Eu (2), Tb (3), and Yb (4)) in very good yield. X-ray crystal structure analyses for 2 and 3 show that (L2)6- accommodates two seven coordinated lanthanide ions in a distorted monocapped trigonal prismatic/octahedral coordination environment. UV-vis spectroscopic titrations performed with La3+, Eu3+, Tb3+ and Yb3+ ions in mixed MeOH/CH2Cl2 solution (I = 0.01 M NBu4PF6) reveal that a 2 : 1 (metal : ligand) stoichiometry is present in solution, with log K11 and K21 values ranging from 5.25 to 6.64. The ratio α = K11/K21 of the stepwise formation constants for the mononuclear (L2 + M = ML2, log K11) and the dinuclear complexes (ML2 + M = M2L2, log K21) was found to be invariably smaller than unity indicating that the binding of the first Ln3+ ion augments the binding of the second Ln3+ ion. The present complexes are less luminescent than other seven-coordinated Eu and Tb complexes, which can be traced to vibrational relaxation of excited EuIII and TbIII states by the coligated MeOH and H2O molecules and/or low-lying ligand-to-metal charge-transfer (LMCT) states. © 2020 The Royal Society of Chemistry.
- ItemEffect of morphology on the photoelectrochemical activity of TiO2 self-organized nanotube arrays(Basel : MDPI, 2020) Ennaceri, Houda; Fischer, Kristina; Hanus, Kevin; Chemseddine, Abdelkrim; Prager, Andrea; Griebel, Jan; Kühnert, Mathias; Schulze, Agnes; Abel, BerndIn the present work, highly ordered titanium dioxide (TiO2) nanotube anodes were grown using a rapid anodization process. The photoelectrochemical performances of these electrodes strongly depend on the anodization conditions. Parameters such as electrolyte composition, anodization potential and anodization time are shown to affect the geometrical parameters of TiO2 nanotubes. The optimal anodization parameters are determined by photocurrent measurements, linear sweep voltammetry and electrochemical impedance spectroscopy. The thickness of the tube wall and its homogeneity is shown to strongly depend on the anodization potential, and the formation mechanism is discussed. This study permits the optimization of the photocurrent density and contributes to further improvement of the photoelectrochemical water-splitting performance of TiO2 nanotube photoelectrodes. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
- ItemComparison of Photocatalytic Membrane Reactor Types for the Degradation of an Organic Molecule by TiO2-Coated PES Membrane(Basel : MDPI, 2020) Regmi, Chhabilal; Lotfi, Shabnam; Espíndola, Jonathan Cawettiere; Fischer, Kristina; Schulze, Agnes; Schäfer, Andrea IrisPhotocatalytic membrane reactors with different configurations (design, flow modes and light sources) have been widely applied for pollutant removal. A thorough understanding of the contribution of reactor design to performance is required to be able to compare photocatalytic materials. Reactors with different flow designs are implemented for process efficiency comparisons. Several figures-of-merit, namely adapted space-time yield (STY) and photocatalytic space-time yield (PSTY), specific energy consumption (SEC) and degradation rate constants, were used to assess the performance of batch, flow-along and flow-through reactors. A fair comparison of reactor performance, considering throughput together with energy efficiency and photocatalytic activity, was only possible with the modified PSTY. When comparing the three reactors at the example of methylene blue (MB) degradation under LED irradiation, flow-through proved to be the most efficient design. PSTY1/PSTY2 values were approximately 10 times higher than both the batch and flow-along processes. The highest activity of such a reactor is attributed to its unique flow design which allowed the reaction to take place not only on the outer surface of the membrane but also within its pores. The enhancement of the mass transfer when flowing in a narrow space (220 nm in flow-through) contributes to an additional MB removal. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
- ItemInteratomic and Intermolecular Coulombic Decay(Washington, DC : ACS Publ., 2020) Jahnke, Till; Hergenhahn, Uwe; Winter, Bernd; Dörner, Reinhard; Frühling, Ulrike; Demekhin, Philipp V.; Gokhberg, Kirill; Cederbaum, Lorenz S.; Ehresmann, Arno; Knie, André; Dreuw, AndreasInteratomic or intermolecular Coulombic decay (ICD) is a nonlocal electronic decay mechanism occurring in weakly bound matter. In an ICD process, energy released by electronic relaxation of an excited atom or molecule leads to ionization of a neighboring one via Coulombic electron interactions. ICD has been predicted theoretically in the mid nineties of the last century, and its existence has been confirmed experimentally approximately ten years later. Since then, a number of fundamental and applied aspects have been studied in this quickly growing field of research. This review provides an introduction to ICD and draws the connection to related energy transfer and ionization processes. The theoretical approaches for the description of ICD as well as the experimental techniques developed and employed for its investigation are described. The existing body of literature on experimental and theoretical studies of ICD processes in different atomic and molecular systems is reviewed. © 2020 American Chemical Society
- ItemSynthesis, Electronic Properties and Reactivity of [B12X11(NO2)]2− (X=F–I) Dianions(Weinheim : Wiley-VCH, 2020) Asmis, Knut R.; Beele, Björn B.; Jenne, Carsten; Kawa, Sebastian; Knorke, Harald; Nierstenhöfer, Marc C.; Wang, Xue-Bin; Warneke, Jonas; Warneke, Ziyan; Yuan, QinqinNitro-functionalized undecahalogenated closo-dodecaborates [B12X11(NO2)]2− were synthesized in high purities and characterized by NMR, IR, and Raman spectroscopy, single crystal X-diffraction, mass spectrometry, and gas-phase ion vibrational spectroscopy. The NO2 substituent leads to an enhanced electronic and electrochemical stability compared to the parent perhalogenated [B12X12]2− (X=F–I) dianions evidenced by photoelectron spectroscopy, cyclic voltammetry, and quantum-chemical calculations. The stabilizing effect decreases from X=F to X=I. Thermogravimetric measurements of the salts indicate the loss of the nitric oxide radical (NO.). The homolytic NO. elimination from the dianion under very soft collisional excitation in gas-phase ion experiments results in the formation of the radical [B12X11O]2−.. Theoretical investigations suggest that the loss of NO. proceeds via the rearrangement product [B12X11(ONO)]2−. The O-bonded nitrosooxy structure is thermodynamically more stable than the N-bonded nitro structure and its formation by radical recombination of [B12X11O]2−. and NO. is demonstrated. © 2020 The Authors. Published by Wiley-VCH GmbH