@article{ZehmLaschewskyGradzielskietal.2010,
  author    = {Zehm, Daniel and Laschewsky, Andr{\´e} and Gradzielski, Michael and Pr{\´e}vost, Sylvain and Liang, Hua and Rabe, J{\"u}rgen P. and Schweins, Ralf and Gummel, J{\´e}r{\´e}mie},
  title     = {Amphiphilic dual brush block copolymers as "giant surfactants" and their aqueous self-assembly},
  issn      = {0743-7463},
  doi       = {10.1021/La903087p},
  year      = {2010},
  abstract  = {Amphiphilic dual brush diblock as well as symmetrical triblock polymers were synthesized by the overlay of the reversible addition-fragmentation chain transfer and the nitroxide mediated polymerization (NMP) techniques. While poly(ethylene glycol) brushes served as hydrophilic block, the hydrophobic block was made of polystyrene brushes. The resulting "giant surfactants" correspond structurally to the established amphiphilic diblock and triblock copolymer known as macrosurfactants. The aggregation behavior of the novel "giant surfactants" in aqueous solution was studied by dynamic light scattering, small-angle neutron scattering (SANS), and small-angle X-ray scattering (SAXS) over a large range in reciprocal space. Further, the self-assembled aggregates Were investigated by scanning force microscopy (SFM) after deposition on differently functionalized ultraflat solid substrates. Despite the high fraction of hydrophobic segments, the polymers form stable mesoscopic, spherical aggregates with hydrodynamic diameters in the range of 150-350 nm. Though prepared from well-defined individual polymers, the aggregates show several similarities to hard core latexes. They are stable enough to he deposited without much changes onto surfaces, where they cluster and show Spontaneous sorting according to their size within the clusters, with the larger aggregates being in the center.},
  language  = {en}
}
@article{XieJelicicWangetal.2010,
  author    = {Xie, Zai-Lai and Jelicic, Aleksandra and Wang, Feipeng and Rabu, Pierre and Friedrich, Alwin and Beuermann, Sabine and Taubert, Andreas},
  title     = {Transparent, flexible, and paramagnetic ionogels based on PMMA and the iron-based ionic liquid 1-butyl-3- methylimidazolium tetrachloroferrate(III) [Bmim][FeCl4]},
  issn      = {0959-9428},
  doi       = {10.1039/C0jm01733g},
  year      = {2010},
  abstract  = {The iron-containing ionic liquid (IL) 1-butyl-3-methylimidazolium tetrachloroferrate(III) [Bmim][FeCl4] has been used as a building block in the synthesis of transparent, ion-conducting, and paramagnetic ionogels. UV/Vis spectroscopy shows that the coordination around the Fe(III) ion does slightly change upon incorporation of the IL into PMMA. The thermal stability of the PMMA increases significantly with IL incorporation. In particular, the onset weight loss observed at ca. 265 degrees C for pure PMMA is completely suppressed. The ionic conductivity shows a strong temperature dependence and increases with increasing IL weight fractions. The magnetic properties are similar to those reported for the pure IL and are not affected by the incorporation into the PMMA matrix. The resulting ionogel is thus an interesting prototype for soft, flexible, and transparent materials combining the mechanical properties of the matrix with the functionality of the metal-containing IL, such as magnetism.},
  language  = {en}
}
@article{WitzelGoetzeEbenhoeh2010,
  author    = {Witzel, Franziska and Goetze, Jan and Ebenhoeh, Oliver},
  title     = {Slow deactivation of ribulose 1,5-bisphosphate carboxylase/oxygenase elucidated by mathematical models},
  issn      = {1742-464X},
  doi       = {10.1111/j.1742-4658.2009.07541.x},
  year      = {2010},
  abstract  = {Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is the key enzyme of the Calvin cycle, catalyzing the fixation of inorganic carbon dioxide to organic sugars. Unlike most enzymes, RuBisCO is extremely slow, substrate unspecific, and catalyzes undesired side-reactions, which are considered to be responsible for the slow deactivation observed in vitro, a phenomenon known as fallover. Despite the fact that amino acid sequences and the 3D structures of RuBisCO from a variety of species are known, the precise molecular mechanisms for the various side reactions are still unclear. In the present study, we investigate the kinetic properties of RuBisCO using mathematical models. Initially, we formulate a minimal model that quantitatively reflects the kinetic behavior of RuBisCOs from different organisms. By relating rate parameters for single molecular steps to experimentally determined K-m and V-max values, we can examine mechanistic differences among species. The minimal model further demonstrates that two inhibitor producing side reactions are sufficient to describe experimentally determined fallover kinetics. To explain the observed kinetics of the limited capacity of RuBisCO to accept xylulose 1,5-bisphosphate as substrate, the inclusion of other side reactions is necessary. Our model results suggest a yet undescribed alternative enolization mechanism that is supported by the molecular structure. Taken together, the presented models serve as a theoretical framework to explain a wide range of observed kinetic properties of RuBisCOs derived from a variety of species. Thus, we can support hypotheses about molecular mechanisms and can systematically compare enzymes from different origins.},
  language  = {en}
}
@article{WischerhoffBadiLutzetal.2010,
  author    = {Wischerhoff, Erik and Badi, Nezha and Lutz, Jean-Francois and Laschewsky, Andr{\´e}},
  title     = {Smart bioactive surfaces},
  issn      = {1744-683X},
  doi       = {10.1039/B913594d},
  year      = {2010},
  abstract  = {The purpose of this highlight is to define the emerging field of bioactive surfaces. In recent years, various types of synthetic materials capable of "communicating'' with biological objects such as nucleic acids, proteins, polysaccharides, viruses, bacteria or living cells have been described in the literature. This novel area of research certainly goes beyond the traditional field of smart materials and includes different types of sophisticated interactions with biological entities, such as reversible adhesion, conformational control, biologically-triggered release and selective permeation. These novel materials may be 2D planar surfaces as well as colloidal objects or 3D scaffolds. Overall, they show great promise for numerous applications in biosciences and biotechnology. For instance, practical applications of bioactive surfaces in the fields of bioseparation, cell engineering, biochips and stem-cell differentiation are briefly discussed herein.},
  language  = {en}
}
@article{WessigMoellnitzHuebner2010,
  author    = {Wessig, Pablo and M{\"o}llnitz, Kristian and H{\"u}bner, Sebastian},
  title     = {A short and efficient route from myo- to neo-inositol},
  issn      = {0936-5214},
  doi       = {10.1055/s-0029-1220071},
  year      = {2010},
  abstract  = {An efficient route from myo- to neo-inositol is described. The key steps of the sequence are oxidation of the hydroxy group at C-5 to the corresponding ketone, followed by a highly (dr = 7.8:1) stereoselective reduction. The route includes nine steps with an overall yield of 51\% and is therefore superior to all hitherto reported methods for the preparation of neo-inositol.},
  language  = {en}
}
@article{WessigMatthesSchilde2010,
  author    = {Wessig, Pablo and Matthes, Annika and Schilde, Uwe},
  title     = {Crystal structure of 3,4-diacetyl-15,21-dioxatetracyclo- [23.4.0.02,7.06,11]nonacosa-1(29),2,4,6,8,10,25,27- octaene- 14,22-dione{\`u}water (1:2), C31H32O6 · 2H2O},
  issn      = {1433-7266},
  year      = {2010},
  language  = {en}
}
@article{WebsterMeier2010,
  author    = {Webster, Dean C. and Meier, Michael A. R.},
  title     = {Polymer libraries : preparation and applications},
  issn      = {0065-3195},
  doi       = {10.1007/12_2009_15},
  year      = {2010},
  abstract  = {Polymer libraries offer straightforward opportunities for the investigation of structure property relationships and for a more thorough understanding of certain research problems. Furthermore, if combined with high-throughput methods for their preparation as well as screening, they offer the additional advantage of time savings and/or the reduction of experimental efforts. Thus, the herein discussed methods of polymer library preparation and selected literature examples of polymer libraries describe efficient and state-of-the-art methods to tackle difficult research challenges in polymer and materials science.},
  language  = {en}
}
@article{WangKaunePerlichetal.2010,
  author    = {Wang, Weijia and Kaune, Gunar and Perlich, Jan and Paradakis, Christine M. and Bivigou Koumba, Achille Mayelle and Laschewsky, Andr{\´e} and Schlage, K. and R{\"o}hlsberger, Ralf and Roth, Stephan V. and Cubitt, Robert and M{\"u}ller-Buschbaum, Peter},
  title     = {Swelling and switching kinetics of gold coated end-capped poly(N-isopropylacrylamide) thin films},
  issn      = {0024-9297},
  doi       = {10.1021/Ma902637a},
  year      = {2010},
  abstract  = {Thin thermoresponsive hydrogel films of poly(N-isopropylacrylamide) end-capped with n-butyltrithiocarbonate(nbc- PNIPAM) oil si I icon supports with a gold layer on top, causing an asymmetric confinement, are investigated. For two different gold layer thicknesses (nominally 0.4 and 5 rim), the swelling and switching kinetics are probed with in situ neutron reflectivity. With a temperature jump from 23 to 40 degrees C the film is switched from a swollen into a collapsed state. For the thin gold layer this switching is faster as compared to the thick gold layer. The switching is a two-step process of water release and a subsequent structural relaxation. fit swelling and deswelling cycles, aging of the films is probed. After five cycles, the film exhibits enhanced water storage capacity. Grazing-incidence small-angle X-ray scattering (GISAXS) shows that these gold coated nbc-PNIPAM films do not age with respect to the inner structure but slightly roughen at the gold surface. As revealed by atomic force microscopy, the morphology of the gold layer is changed by the water uptake and release.},
  language  = {en}
}
@article{VukicevicHierzenbergerHildetal.2010,
  author    = {Vukicevic, Radovan and Hierzenberger, Peter and Hild, Sabine and Beuermann, Sabine},
  title     = {Functionalization of carbon black nanoparticles with poly(vinylidene fluoride)},
  issn      = {0887-624X},
  doi       = {10.1002/Pola.24277},
  year      = {2010},
  abstract  = {The surface of carbon black (CB) nanoparticles was functionalized with poly(vinylidene fluoride) (PVDF) either by trapping of macroradicals or by cycloaddition. PVDF with two iodine end groups (I-PVDF-I) obtained from iodine transfer polymerization in supercritical CO2 was heated in the presence of CB and the C-I bond was cleaved resulting in a reaction between the macroradical and the CB surface. To allow for cycloaddition of PVDF to the CB surface for a number of polymers, the iodine end groups were replaced by azide end groups. In addition, microwave irradiation was applied to the functionalization. The influence of temperature, time, polymer concentration, and polymer molar mass on the functionalization reaction was examined.},
  language  = {en}
}
@article{UhligWischerhoffLutzetal.2010,
  author    = {Uhlig, Katja and Wischerhoff, Erik and Lutz, Jean-Francois and Laschewsky, Andr{\´e} and J{\"a}ger, Magnus S. and Lankenau, Andreas and Duschl, Claus},
  title     = {Monitoring cell detachment on PEG-based thermoresponsive surfaces using TIRF microscopy},
  issn      = {1744-683X},
  doi       = {10.1039/C0sm00010h},
  year      = {2010},
  abstract  = {Recently, we introduced a thermoresponsive copolymer that consists of oligo(ethylene glycol) methacrylate (OEGMA) and 2-(2- methoxyethoxy) ethyl methacrylate (MEO(2)MA). The polymer exhibited an LCST at 35 degrees C in PBS buffer and was anchored onto gold substrates using disulfide polymerisation initiators. It allows the noninvasive detachment of adherent cells from their substrate. As the mechanisms that determine the interaction of cells with such polymers are not well understood, we employed Total Internal Reflection Fluorescence (TIRF) microscopy in order to monitor the detachment process of cells of two different types. We identified contact area and average cell-substrate distance as crucial parameters for the evaluation of the detachment process. The sensitivity of TIRF microscopy allowed us to correlate the specific adhesion pattern of MCF-7 breast cancer cells with the morphology of cell deposits that may serve as fingerprints for a nondestructive characterisation of live cells.},
  language  = {en}
}
@article{TueruencMeier2010,
  author    = {T{\"u}r{\"u}nc, Oguz and Meier, Michael A. R.},
  title     = {Fatty acid derived monomers and related polymers via Thiol-ene (click) additions},
  issn      = {1022-1336},
  doi       = {10.1002/marc.201000291},
  year      = {2010},
  abstract  = {Thiol-ene additions of methyl 10-undecenoate, a castor oil derived renewable platform chemical, were studied with the goal of preparing a set of renewable monomers. Good to excellent yields were obtained for these solvent and initiator free thiol-ene additions. The resulting monomers were then polymerized using TBD as a catalyst, to linear as well as hyperbranched polyesters that also contain thio-ether linkages. All thus prepared polymers were fully characterized (NMR, GPC, DSC, and TGA) and the results of these investigations will be discussed within this contribution. The thermal analysis of these polymers revealed melting points in the range from 50 to 71 degrees C. Moreover, no significant weight loss was observed below 300 degrees C.},
  language  = {en}
}
@article{TronciNeffePierceetal.2010,
  author    = {Tronci, Giuseppe and Neffe, Axel T. and Pierce, Benjamin Franklin and Lendlein, Andreas},
  title     = {An entropy-elastic gelatin-based hydrogel system},
  issn      = {0959-9428},
  doi       = {10.1039/C0jm00883d},
  year      = {2010},
  abstract  = {Gelatin is a non-immunogenic and degradable biopolymer, which is widely applied in the biomedical field e. g. for drug capsules or as absorbable hemostats. However, gelatin materials present limited and hardly reproducible mechanical properties especially in aqueous systems, particularly caused by the uncontrollable partial renaturation of collagen-like triple helices. Therefore, mechanically demanding applications for gelatin-based materials, such as vascular patches, i.e. hydrogel films that seal large incisions in vessel walls, and for induced autoregeneration, are basically excluded if this challenge is not addressed. Through the synthesis of a defined chemical network of gelatin with hexamethylene diisocyanate (HDI) in DMSO, the self-organization of gelatin chains could be hindered and amorphous gelatin films were successfully prepared having Young's moduli of 60-530 kPa. Transferring the crosslinking reaction with HDI and, alternatively, ethyl lysine diisocyanate (LDI), to water as reaction medium allowed the tailoring of swelling behaviour and mechanical properties by variation of crosslinker content while suppressing the formation of helices. The hydrogels had Young's moduli of 70-740 kPa, compressive moduli of 16-48 kPa, and degrees of swelling of 300-800 vol\%. Test reactions investigated by ESI mass spectrometry allowed the identification and quantification of reaction products of the crosslinking reaction. The HDI crosslinked networks were stabilized by direct covalent crosslinks (ca. 10 mol\%), supported by grafting (50 mol\%) and blending of hydrophobic oligomeric chains. For the LDI- based networks, less crosslinked (3 mol\%) and grafted species (5 mol\%) and much higher amounts of oligomers were observed. The adjustable hydrogel system enables the application of gelatin-based materials in physiological environments.},
  language  = {en}
}
@article{TremblayMonturetSaalfrank2010,
  author    = {Tremblay, Jean Christophe and Monturet, Serge and Saalfrank, Peter},
  title     = {Electronic damping of anharmonic adsorbate vibrations at metallic surfaces},
  issn      = {1098-0121},
  doi       = {10.1103/Physrevb.81.125408},
  year      = {2010},
  abstract  = {The nonadiabatic coupling of an adsorbate close to a metallic surface leads to electronic damping of adsorbate vibrations and line broadening in vibrational spectroscopy. Here, a perturbative treatment of the electronic contribution to the lifetime broadening serves as a building block for a new approach, in which anharmonic vibrational transition rates are calculated from a position-dependent coupling function. Different models for the coupling function will be tested, all related to embedding theory. The first two are models based on a scattering approach with (i) a jellium-type and (ii) a density functional theory based embedding density, respectively. In a third variant a further refined model is used for the embedding density, and a semiempirical approach is taken in which a scaling factor is chosen to match harmonic, single-site, first-principles transition rates, obtained from periodic density functional theory. For the example of hydrogen atoms on (adsorption) and below (subsurface absorption) a Pd(111) surface, lifetimes of and transition rates between vibrational levels are computed. The transition rates emerging from different models serve as input for the selective subsurface adsorption of hydrogen in palladium starting from an adsorption site, by using sequences of infrared laser pulses in a laser distillation scheme.},
  language  = {en}
}
@article{TremblayKrauseKlamrothetal.2010,
  author    = {Tremblay, Jean Christophe and Krause, Pascal and Klamroth, Tillmann and Saalfrank, Peter},
  title     = {Time-dependent response of dissipative electron systems},
  issn      = {1050-2947},
  doi       = {10.1103/Physreva.81.063420},
  year      = {2010},
  abstract  = {We present a systematic study of the influence of energy and phase relaxation on dynamic polarizability simulations in the linear response regime. The nonperturbative approach is based on explicit electron dynamics using short laser pulses of low intensities. To include environmental effects on the property calculation, we use the time- dependent configuration-interaction method in its reduced density matrix formulation. Both energy dissipation and nonlocal pure dephasing are included. The explicit treatment of time-resolved electron dynamics gives access to the phase shift between the electric field and the induced dipole moment, which can be used to define a useful uncertainty measure for the dynamic polarizability. The nonperturbative treatment is compared to perturbation theory expressions, as applied to a simple model system, the rigid H-2 molecule. It is shown that both approaches are equivalent for low field intensities, but the time-dependent treatment provides complementary information on the phase of the induced dipole moment, which allows for the definition of an uncertainty associated with the computation of the dynamic polarizability in the linear response regime.},
  language  = {en}
}
@article{TiseanuParvulescuParvulescuetal.2010,
  author    = {Tiseanu, Carmen and Parvulescu, Vasile and Parvulescu, Victoria and Cotoi, Elena and Gessner, Andre and Kumke, Michael Uwe and Simon, Simion and Vasiliu, Florin},
  title     = {Structural and photoluminescence characterization of mesoporous silicon-phosphates},
  issn      = {1010-6030},
  doi       = {10.1016/j.jphotochem.2010.07.015},
  year      = {2010},
  abstract  = {Two different types of mesoporous silicon-phosphate supports using different surfactants (a mixture of (CH3)(3)C13H27NBr with an organophosphorus coupling molecule (HO-PO(i-C3H7)(2)) and with a co-surfactant ((C2H5)(3)(C6H5)PCl), respectively) were synthesized. Trivalent europium (Eu) ions were immobilized via ion-exchange on these supports. The resulting materials were characterized using nitrogen adsorption isotherms at -196 degrees C, thermogravimetric analysis, SEM, TEM, FT-IR, PXRD, CP/MAS. (HSi)-H-1-Si-29 and P-31 NMR, DR-UV-vis as well as steady- state and time-resolved photoluminescence spectroscopy. The results evidenced that the co-polymerization of silicon and phosphorous yielded a unique morphology in these materials. Following calcination at 450 and 900 degrees C europium- exchanged silicon-phosphates with great surface area (BET=600-705 m(2) g(-1)) and 3.4 nm sized mesopores were obtained. The differences among the optical properties of the non-calcined europium materials such as the emission lifetimes, local environment at the europium sites or the relative contribution of the upper excited levels to the total photoluminescence were assigned to the surfactants used in the synthesis. Calcination of the silicon-phosphates at higher temperatures than 450 degrees C did not induce major changes in the structural properties: in contrast, photoluminescence properties of europium were markedly improved in terms of intensity and average lifetime.},
  language  = {en}
}
@article{TiseanuParvulescuCojocaruetal.2010,
  author    = {Tiseanu, Carmen and Parvulescu, Vasile Ion and Cojocaru, Bogdan and Lorenz-Fonfria, Victor A. and Kumke, Michael Uwe and Gessner, Andre and Enculescu, Ion},
  title     = {Polymer-microporous host interactions probed by photoluminescence spectroscopy},
  issn      = {1463-9076},
  doi       = {10.1039/B922591a},
  year      = {2010},
  abstract  = {Zeolites NaY and ZSM-5 were used as hosts for styrene polymerization after ion-exchange with europium ions. The parent and hybrid, polystyrene coated Eu-NaY (Eu-NaY/PS) and Eu-ZSM-5 (Eu-ZSM-5/PS) zeolites were investigated by using thermal analysis, SEM, PXRD, FT-IR, DR-UV/Vis, steady state and time-resolved photoluminescence spectroscopy. FT-IR spectra evidenced for the interaction between the zeolitic hosts and polystyrene while the PXRD spectra supported for the presence of the polymer inside the channels/pores of Eu-NaY/PS and Eu-ZSM-5/PS materials. The optical properties of Eu-NaY/PS and Eu-ZSM-5/PS were significantly changed relative to those of the parent zeolites, giving further evidence for the presence of polymer inside zeolites. An interesting case is presented by NaY zeolite: following styrene polymerization, the polymer interacted selectively with one of the two main species co-existing inside zeolite while for ZSM-5 a similar effect was not observed.},
  language  = {en}
}
@article{StrehmelRexhausenStrauchetal.2010,
  author    = {Strehmel, Veronika and Rexhausen, Hans and Strauch, Peter and Strehmer, Bernd},
  title     = {Temperature dependence of interactions between stable piperidine-1-yloxyl derivatives and a semicrystalline ionic liquid},
  issn      = {1439-4235},
  doi       = {10.1002/cphc.200900977},
  year      = {2010},
  abstract  = {The stable 2,2,6,6-tetramethylpiperidine-1-yloxyl and its derivatives with hydrogen-bond-forming (-OH, -OSO3H), anionic (-OSO3- bearing K+ or [K(18-crown-6)](+) as counter ion), or cationic (-N+-(CH3)(3) bearing I-, BF4-, PF6- or N- (SO2CF3)(2) as counter ion) substituents are investigated in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide over a wide temperature range. The temperature dependence of the viscosity of the ionic liquid is well described by the Vogel-Fulcher-Tammann equation. Interestingly, the temperature dependence of the rotational correlation time of the spin probes substituted with either a hydrogen-bond-forming group or an ionic substituent can be described using the Stokes-Einstein equation. In contrast, the temperature dependence of the rotational correlation time of the spin probe without an additional substituent at the 4-position to the nitroxyl group does not follow this trend. The activation energy for the mobility of the unsubstituted spin probe, determined from an Arrhenius plot of the spin-probe mobility in the ionic liquid above the melting temperature, is comparable with the activation energy for the viscous flow of the ionic liquid, but is higher for spin probes bearing an additional substituent at the 4-position. Quantum chemical calculations of the spin probes using the 6-31G+d method give information about the rotational volume of the spin probes and the spin density at the nitrogen atom of the radical structure as a function of the substituent at the spin probes in the presence and absence of a counter ion. The results of these calculations help in understanding the effect of the additional substituent on the experimentally determined isotropic hyperfine coupling constant.},
  language  = {en}
}
@article{StrehmelRexhausenStrauch2010,
  author    = {Strehmel, Veronika and Rexhausen, Hans and Strauch, Peter},
  title     = {2,2,6,6-Tetramethylpiperidine-1-yloxyl bound to the imidazolium ion by an acetamido group for investigation of ionic liquids},
  issn      = {0040-4039},
  doi       = {10.1016/j.tetlet.2009.11.124},
  year      = {2010},
  abstract  = {New spin probes bearing the 2,2,6,6-tetramethylpiperidine-1-yloxyl covalently bound to the imidazolium ion via a methylene spacer and an amide group are synthesized. If the anion is bis(trifluoromethylsulfonylimide) instead of iodide, the new spin probe has a similar structure as that of an ionic liquid. Nevertheless, the new spin probes are useful tools to investigate ionic liquids.},
  language  = {en}
}
@article{StrehmelRexhausenStrauch2010,
  author    = {Strehmel, Veronika and Rexhausen, Hans and Strauch, Peter},
  title     = {Influence of imidazolium bis(trifluoromethylsulfonylimide)s on the rotation of spin probes comprising ionic and hydrogen bonding groups},
  issn      = {1463-9076},
  doi       = {10.1039/B920586a},
  year      = {2010},
  abstract  = {The influence of the alkyl chain length in 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonylimide)s is studied to explore the rotation of piperidine-1-yloxyl derivatives substituted with either hydrogen bonding hydroxy group or ionic substituents, such as the cationic trimethylammonium or the anionic sulfate group placed at the 4 position. Structural variation of the ionic liquids results in differences of their viscosity influencing the rotation of the spin probes. The size of the average rotational correlation times of the spin probes dissolved in the ionic liquids depends further on the additional substituent in 4-position at these spin probes. The rotational correlation time exhibits a linear dependence on the ionic liquid viscosity in the case of the spin probe forming hydrogen bonding with the ionic liquids. In contrast to this, a deviation from the Stokes-Einstein behavior is found in the case of rotation of the charged spin probes in the 1-alkyl-3-methylimidazolium bis( trifluoromethylsulfonylimide) s substituted with a longer alkyl chain. This effect may be explained by phase separation on a molecular level between the charged part of the ionic liquid and the longer alkyl chains bound at the imidazolium ion. Although the neutral and the cationic spin probes show only a slight dependence between ionic liquid structure variation and the hyperfine coupling constants, structural effects cause changes in the hyperfine coupling constants in the case of the anionic spin probes. These probes strongly interact with the imidazolium ion.},
  language  = {en}
}
@article{StrehmelLungwitzRexhausenetal.2010,
  author    = {Strehmel, Veronika and Lungwitz, Ralf and Rexhausen, Hans and Spange, Stefan},
  title     = {Relationship between hyperfine coupling constants of spin probes and empirical polarity parameters of some ionic liquids},
  issn      = {1144-0546},
  doi       = {10.1039/C0nj00253d},
  year      = {2010},
  abstract  = {The polarity of 1-alkyl-3-methylimidazolium-based ionic liquids containing hexafluorophosphate, tetrafluoroborate, dicyanoimide, or bis(trifluoromethanesulfonyl) imide as anions and a variation of the alkyl-chain length of the cation are investigated by both solvatochromic dyes and spin probes. Two different polarity scales are used for discussion of the polarity of these ionic liquids. These polarity scales are the empirical Kamlet-Taft parameters alpha, beta, and pi* and the hyperfine coupling constants A(iso)(N-14) obtained for spin probes substituted either with an ammonio or a sulfate group at 4-position. The results show that both polarity scales are valid for description of the ionic liquid polarity although differences are found between the two polarity scales. The most clear trend is found in all ionic liquids investigated for the hydrogen-bond accepting ability (beta) and the hyperfine- coupling constant of the anionic spin probe, where both parameters increase for all ionic liquids investigated until an alkyl chain length of eight carbon atoms and keep constant at longer alkyl chains.},
  language  = {en}
}