TY - JOUR A1 - Unuabonah, Emmanuel I. A1 - Taubert, Andreas T1 - Clay-polymer nanocomposites (CPNs): Adsorbents of the future for water treatment JF - Applied clay science : an international journal on the application and technology of clays and clay minerals N2 - A class of adsorbents currently receiving growing attention is the clay-polymer nanocomposite (CPN) adsorbents. CPNs effectively treat water by adsorption and flocculation of both inorganic and organic micropollutants from aqueous solutions. Some of these CPNs - when modified with biocides - also have the ability to efficiently remove microorganisms such as Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans from water. CPNs are far more easily recovered from aqueous media than neat clay. They also exhibit far better treatment times than either polymer or clay adsorbents. They have higher adsorption capacity and better life cycles compared with clay alone. CPNs therefore show an excellent potential as highly efficient water and waste treatment agents. This article reviews the various CPNs that have been prepared recently and used as adsorbents in the removal of micropollutants (inorganic, organic and biological) from aqueous solutions. A special focus is placed on CPNs that are not only interesting from an academic point of view but also effectively reduce the concentration of micropollutants in water to safe limits and also on new developments bordering on CPN use as water treatment agent that have not yet realized their full potential. (C) 2014 Elsevier B.V. All rights reserved. KW - Clay-polymer nanocomposite - CPN KW - Micropollutants KW - Adsorbent KW - Water treatment KW - Microorganism KW - Desorption Y1 - 2014 U6 - https://doi.org/10.1016/j.clay.2014.06.016 SN - 0169-1317 SN - 1872-9053 VL - 99 SP - 83 EP - 92 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Laschewsky, André T1 - Structures and synthesis of zwitterionic polymers JF - Polymers N2 - The structures and synthesis of polyzwitterions ("polybetaines") are reviewed, emphasizing the literature of the past decade. Particular attention is given to the general challenges faced, and to successful strategies to obtain polymers with a true balance of permanent cationic and anionic groups, thus resulting in an overall zero charge. Also, the progress due to applying new methodologies from general polymer synthesis, such as controlled polymerization methods or the use of "click" chemical reactions is presented. Furthermore, the emerging topic of responsive ("smart") polyzwitterions is addressed. The considerations and critical discussions are illustrated by typical examples. KW - review KW - polyzwitterion KW - polyampholyte KW - zwitterionic group KW - betaine KW - synthesis KW - monomer KW - polymerization KW - post-polymerization modification Y1 - 2014 U6 - https://doi.org/10.3390/polym6051544 SN - 2073-4360 VL - 6 IS - 5 SP - 1544 EP - 1601 PB - MDPI CY - Basel ER - TY - JOUR A1 - Körzdörfer, Thomas A1 - Bredas, Jean-Luc T1 - Organic electronic materials: recent advances in the DFT description of the ground and excited states using tuned range-separated hybrid functionals JF - Accounts of chemical research N2 - CONSPECTUS: Density functional theory (DFT) and its time-dependent extension (TD-DFT) are powerful tools enabling the theoretical prediction of the ground- and excited-state properties of organic electronic materials with reasonable accuracy at affordable computational costs. Due to their excellent accuracy-to-numerical-costs ratio, semilocal and global hybrid functionals such as B3LYP have become the workhorse for geometry optimizations and the prediction of vibrational spectra in modern theoretical organic chemistry. Despite the overwhelming success of these out-of-the-box functionals for such applications, the computational treatment of electronic and structural properties that are of particular interest in organic electronic materials sometimes reveals severe and qualitative failures of such functionals. Important examples include the overestimation of conjugation, torsional barriers, and electronic coupling as well as the underestimation of bond-length alternations or excited-state energies in low-band-gap polymers. In this Account, we highlight how these failures can be traced back to the delocalization error inherent to semilocal and global hybrid functionals, which leads to the spurious delocalization of electron densities and an overestimation of conjugation. The delocalization error for systems and functionals of interest can be quantified by allowing for fractional occupation of the highest occupied molecular orbital. It can be minimized by using long-range corrected hybrid functionals and a nonempirical tuning procedure for the range-separation parameter. We then review the benefits and drawbacks of using tuned long-range corrected hybrid functionals for the description of the ground and excited states of pi-conjugated systems. In particular, we show that this approach provides for robust and efficient means of characterizing the electronic couplings in organic mixed-valence systems, for the calculation of accurate torsional barriers at the polymer limit, and for the reliable prediction of the optical absorption spectrum of low-band-gap polymers. We also explain why the use of standard, out-of-the-box range-separation parameters is not recommended for the DFT and/or TD-DFT description of the ground and excited states of extended, pi-conjugated systems. Finally, we highlight a severe drawback of tuned range-separated hybrid functionals by discussing the example of the calculation of bond-length alternation in polyacetylene, which leads us to point out the challenges for future developments in this field. Y1 - 2014 U6 - https://doi.org/10.1021/ar500021t SN - 0001-4842 SN - 1520-4898 VL - 47 IS - 11 SP - 3284 EP - 3291 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Kleinpeter, Erich ED - Webb, GA T1 - Quantification and visualization of the anisotropy effect in NMR spectroscopy by through-space NMR shieldings JF - Annual reports on NMR spectroscopy JF - Annual Reports on NMR Spectroscopy N2 - The anisotropy effect of functional groups (respectively the ring-current effect of aryl moieties) in H-1 NMR spectra has been computed as spatial NICS (through-space NMR chemical shieldings) and visualized by iso-chemical-shielding surfaces of various size and low(high) field direction. Hereby, the anisotropy/ring-current effect, which proves to be the molecular response property of spatial NICS, can be quantified and can be readily employed for assignment purposes in proton NMR spectroscopy-characteristic examples of stereochemistry and position assignments (the latter in supramolecular structures) will be given. In addition, anisotropy/ring-current effects in H-1 NMR spectra can be quantitatively separated from the second dominant structural effect in proton NMR spectra, the steric compression effect, pointing into the reverse direction, and the ring-current effect, by far the strongest anisotropy effect, can be impressively employed to visualize and quantify (anti) aromaticity and to clear up standing physical-organic phenomena as are pseudo-, spherical, captodative, homo-and chelatoaromaticity, to characterize the pi-electronic structure of, for example, fulvenes, fulvalenes, annulenes or fullerenes and to differentiate aromatic and quinonoid structures. KW - Through-space NMR shielding (TSNMRS) KW - Anisotropy effect KW - Stereochemistry KW - Ring-current effect KW - Aromatic or quinonoid KW - Aromaticity KW - Chelatoaromaticity KW - Binding pocket position KW - Supramolecular compounds KW - Diastereomers assignment Y1 - 2014 SN - 978-0-12-800184-4 U6 - https://doi.org/10.1016/B978-0-12-800184-4.00003-5 SN - 0066-4103 VL - 82 SP - 115 EP - 166 PB - Elsevier CY - San Diego ER - TY - JOUR A1 - Bandrauk, Andre D. A1 - Paramonov, Guennaddi K. T1 - Excitation of muonic molecules dd mu and dt mu by super-intense attosecond soft X-ray laser pulses: Shaped post-laser-pulse muonic oscillations and enhancement of nuclear fusion JF - International journal of modern physics : E, Nuclear physics N2 - The quantum dynamics of muonic molecular ions dd mu and dt mu excited by linearly polarized along the molecular (z)-axis super-intense laser pulses is studied beyond the Born-Oppenheimer approximation by the numerical solution of the time-dependent Schrodinger equation within a three-dimensional model, including the internuclear distance R and muon coordinates z and rho. The peak-intensity of the super-intense laser pulses used in our simulations is I-0 = 3.51 x 10(22) W/cm(2) and the wavelength is lambda(l) = 5nm. In both dd mu and dt mu, expectation values < z > and of muon demonstrate "post-laser-pulse" oscillations after the ends of the laser pulses. In dd mu post-laser-pulse z-oscillations appear as shaped nonoverlapping "echo-pulses". In dt mu post-laser-pulse muonic z-oscillations appear as comparatively slow large-amplitude oscillations modulated with small-amplitude pulsations. The post-laser-pulse rho-oscillations in both dd mu and dt mu appear, for the most part, as overlapping "echo-pulses". The post-laser-pulse oscillations do not occur if the Born-Oppenheimer approximation is employed. Power spectra generated due to muonic motion along both optically active z and optically passive rho degrees of freedom are calculated. The fusion probability in dt mu can be increased by more than 11 times by making use of three sequential super-intense laser pulses. The energy released from the dt fusion in dt mu can by more than 20 GeV exceed the energy required to produce a usable muon and the energy of the laser pulses used to enhance the fusion. The possibility of power production from the laser-enhanced muon-catalyzed fusion is discussed. KW - Muonic molecules KW - super-intense laser pulses KW - laser-enhanced nuclear fusion Y1 - 2014 U6 - https://doi.org/10.1142/S0218301314300148 SN - 0218-3013 SN - 1793-6608 VL - 23 IS - 9 PB - World Scientific CY - Singapore ER - TY - JOUR A1 - Bald, Ilko A1 - Keller, Adrian T1 - Molecular processes studied at a single-molecule level using DNA origami nanostructures and atomic force microscopy JF - Molecules N2 - DNA origami nanostructures allow for the arrangement of different functionalities such as proteins, specific DNA structures, nanoparticles, and various chemical modifications with unprecedented precision. The arranged functional entities can be visualized by atomic force microscopy (AFM) which enables the study of molecular processes at a single-molecular level. Examples comprise the investigation of chemical reactions, electron-induced bond breaking, enzymatic binding and cleavage events, and conformational transitions in DNA. In this paper, we provide an overview of the advances achieved in the field of single-molecule investigations by applying atomic force microscopy to functionalized DNA origami substrates. KW - DNA origami KW - atomic force microscopy KW - single-molecule analysis KW - DNA radiation damage KW - protein binding KW - enzyme reactions KW - G quadruplexes Y1 - 2014 U6 - https://doi.org/10.3390/molecules190913803 SN - 1420-3049 VL - 19 IS - 9 SP - 13803 EP - 13823 PB - MDPI CY - Basel ER -