Johannes Ranke

Publications of Johannes Ranke

• Determination of LFER Descriptors of 30 Cations of Ionic Liquids-Progress in Understanding Their Molecular Interaction Potentials.

  Authors: Chul-Woong Cho, Christian Jungnickel, Stefan Stolte, Ulrich Preiss, Jürgen Arning, Johannes Ranke, Ingo Krossing, Jorg Thöming

  Chemphyschem : a European journal of chemical physics and physical chemistry. 02/2012; 13(3):780-7.

  In order to understand molecular interaction potentials of 30 cations of ionic liquids (ILs), the well-known linear free energy relationship concept (LFER) was applied. The LFER descriptors for theIn order to understand molecular interaction potentials of 30 cations of ionic liquids (ILs), the well-known linear free energy relationship concept (LFER) was applied. The LFER descriptors for the excess molar refractivity and the molar volume were calculated in silico and for hydrogen-bonding acidity and basicity, and the polarizability/dipolarity of IL cations were experimentally determined through high performance liquid chromatography (HPLC) measurements. For the study, three different columns (RP-select B, Cyan, and Diol) and buffered mobile phases, based on two organic solvents acetonitrile (ACN) and methanol (MeOH), were selectively combined to the HPLC separation systems RP-select B-ACN, RP-select B-MeOH, Cyan-MeOH, Diol-ACN, and Diol-MeOH. By measuring the retention factors of 45 neutral calibration compounds and calculating LFER descriptors of three cations in the HPLC systems, the system parameters, including an ionic z coefficient, were determined. Conversely, the LFER descriptors of 30 ionic liquid cations were determined, based on the parameters of five systems and their retention factors in the HPLC systems. The results showed that the type of head group, alkyl chain length and further substituents of the cation have a significant influence on the dipolarity/polarizability and the hydrogen-bonding acidity, and functionalized groups (hydroxyl, ether, and dimethylamino) lead to hydrogen-bonding basicity of the cation. The characterization of cationic LFER descriptors opens up the chance for a more quantitative understanding of molecular interaction potentials and physicochemical properties of ILs.

• Ionic liquids: predictions of physicochemical properties with experimental and/or DFT-calculated LFER parameters to understand molecular interactions in solution.

  Authors: Chul-Woong Cho, Ulrich Preiss, Christian Jungnickel, Stefan Stolte, Jürgen Arning, Johannes Ranke, Andreas Klamt, Ingo Krossing, Jorg Thöming

  The journal of physical chemistry. B. 05/2011; 115(19):6040-50.

  In this article, we present evolutionary models to predict the octanol-water partition coefficients (log P), water solubilities, and critical micelle concentrations (CMCs) of ionic liquids (ILs), asIn this article, we present evolutionary models to predict the octanol-water partition coefficients (log P), water solubilities, and critical micelle concentrations (CMCs) of ionic liquids (ILs), as well as the anionic activity coefficients and hydrophobicities in pure water and octanol-water. They are based on a polyparameter linear free energy relationship (LFER) using measured and/or DFT-calculated LFER parameters: hydrogen-bonding acidity (A), hydrogen-bonding basicity (B), polarizability/dipolarity (S), excess molar refraction (E), and McGowan volume (V) of IL ions. With both calculated or experimental LFER descriptors of IL ions, the physicochemical parameters were predicted with an errors of 0.182-0.217 for the octanol-water partition coefficient and 0.131-0.166 logarithmic units for the water solubility. Because experimentally determined solute parameters of anions are not currently available, the CMC, anionic activity coefficient, and hydrophobicity were predicted with quantum-chemical methods with R(2) values of at least 0.99, as well as errors below 0.168 logarithmic units. These new approaches will facilitate the assessment of the technical applicability and environmental fate of ionic compounds even before their synthesis.

• Analyzing Cytotoxic Effects of Selected Isothiazol-3-one Biocides Using the Toxic Ratio Concept and Structure-Activity Relationship Considerations.

  Authors: Jürgen Arning, Marianne Matzke, Stefan Stolte, Frauke Nehen, Ulrike Bottin-Weber, Andrea Böschen, Salha Abdulkarim, Bernd Jastorff, Johannes Ranke

  Chemical research in toxicology. 11/2009;

  To demonstrate how baseline toxicity can be separated from other more specific modes of toxic action and to address possible pitfals when dealing with hydrophobic substances, the fourTo demonstrate how baseline toxicity can be separated from other more specific modes of toxic action and to address possible pitfals when dealing with hydrophobic substances, the four isothiazol-3-one biocides N-methylisothiazol-3-one (MIT), 5-chloro-N-methylisothiazol-3-one (CIT), N-octylisothiazol-3-one (OIT), and 4,5-dichloro-N-octylisothiazol-3-one (DCOIT) as an example for reactive electrophilic xenobiotics were tested for their cytotoxic effects on the human hepatoblastoma cell line Hep G2, on the marine bacterium Vibrio fischeri, and on the limnic green alga Scenedesmus vacuolatus. In each of the three test systems, toxic effects were observed in a consistent pattern. The two chlorinated compounds and OIT were found to be significantly more toxic than MIT. As compared to baseline toxicants, the small and polar MIT and CIT exhibited pronounced excess toxicity in each of the three test systems that is presumably triggered by their intrinsic reactivity toward cellular thiols. In contrast, OIT and DCOIT showed mainly toxicities that could be explained by their hydrophobicity. Analyzing and comparing these results using the toxic ratio concept and with data that indicate a dramatic depletion of cellular glutathione levels after incubation with DCOIT reveals that for highly hydrophobic substances, baseline level toxicity in an assay for acute toxicity can lead to an oversight of other more specific modes of toxic action that may cause significant effects that might be less reversible than those caused by unreactive baseline toxicants. This possibility should be taken into account in the hazard assessment of chemicals that are both hydrophobic and reactive.

• Explaining ionic liquid water solubility in terms of cation and anion hydrophobicity.

  Authors: Johannes Ranke, Alaa Othman, Ping Fan, Anja Müller

  International journal of molecular sciences. 04/2009; 10(3):1271-89.

  The water solubility of salts is ordinarily dictated by lattice energy and ion solvation. However, in the case of low melting salts also known as ionic liquids, lattice energy is immaterial andThe water solubility of salts is ordinarily dictated by lattice energy and ion solvation. However, in the case of low melting salts also known as ionic liquids, lattice energy is immaterial and differences in hydrophobicity largely account for differences in their water solubility. In this contribution, the activity coefficients of ionic liquids in water are split into cation and anion contributions by regression against cation hydrophobicity parameters that are experimentally determined by reversed phase liquid chromatography. In this way, anion hydrophobicity parameters are derived, as well as an equation to estimate water solubilities for cation-anion combinations for which the water solubility has not been measured. Thus, a new pathway to the quantification of aqueous ion solvation is shown, making use of the relative weakness of interactions between ionic liquid ions as compared to their hydrophobicities.

• Structure-activity relationships for the impact of selected isothiazol-3-one biocides on glutathione metabolism and glutathione reductase of the human liver cell line Hep G2.

  Authors: Jürgen Arning, Ralf Dringen, Maike Schmidt, Anette Thiessen, Stefan Stolte, Marianne Matzke, Ulrike Bottin-Weber, Birgit Caesar-Geertz, Bernd Jastorff, Johannes Ranke

  Toxicology. 05/2008; 246(2-3):203-12.

  To investigate the toxic mode of action of isothiazol-3-one biocides the four compounds N-methylisothiazol-3-one (MIT), 5-chloro-N-methylisothiazol-3-one (CIT), N-octylisothiazol-3-one (OIT) andTo investigate the toxic mode of action of isothiazol-3-one biocides the four compounds N-methylisothiazol-3-one (MIT), 5-chloro-N-methylisothiazol-3-one (CIT), N-octylisothiazol-3-one (OIT) and 4,5-dichloro-N-octylisothiazol-3-one (DCOIT) were purified and tested as single chemical entities for their effects on the human hepatoblastoma cell line Hep G2 and on isolated and cellular glutathione reductase GR). The two chlorinated substances CIT and DCOIT significantly decreased the amount of total cellular glutathione (GSx) in a dose and time dependent manner. Concomitantly, an increase in the level of oxidised glutathione (GSSG) was observed. The resulting shift in the GSH/GSSG ratio entailing the breakdown of the cellular thiol reduction potential was accompanied by necrotic morphological changes like swelling of the plasma membrane and subsequent lysis of the cells. Additionally, CIT and DCOIT were found to inhibit cellular GR in the cells in a concentration dependent manner. The T-SAR-based (thinking in terms of structure-activity relationships) comparison of the chlorine-substituted structures CIT and DCOIT with their non-chlorinated and less active analogues MIT and OIT identified the chlorine substituents and the resulting reaction mechanisms to be the key structural mediators of the observed toxic effects. Furthermore, differences in the activity of both chlorinated substances could be explained using the T-SAR approach to link the lipophilicity and the intrinsic glutathione-reactivity of the compounds to the expected target site concentrations inside the cells.

• Risk assessment of biocides in roof paint. Part 1: experimental determination and modelling of biocide leaching from roof paint.

  Authors: Christian Jungnickel, Frauke Stock, Thomas Brandsch, Johannes Ranke

  Environmental science and pollution research international. 05/2008; 15(3):258-65.

  Many surface coatings, including roof paints, contain biocides. It is generally not known to what extent roof paint biocides leach from the paint, and consequently, what concentration the biocide mayMany surface coatings, including roof paints, contain biocides. It is generally not known to what extent roof paint biocides leach from the paint, and consequently, what concentration the biocide may attain in a rainwater collection system. To this end the leaching of specific biocides from a variety of German roof paints was investigated and the resulting concentrations in collected rain water were estimated. A laboratory simulation was used to determine the time dependant leaching rate of the biocide from the paint into synthetic rainwater. The concentrations of biocide in the leachate were quantified using HPLC. The course of the leachate concentrations over time was fitted using a simple mathematical model. This was then used to estimate concentrations of biocides in a typical household rainwater collection system over time. Surprisingly, the biocides found in the paints did not always concur with the declared biocides. Concerning the modelling of runoff concentrations, it was found that--under the model assumptions--the rain intensity and cumulative raining time after application are the dominant factors influencing the concentration of the biocide. At the highest modelled rain intensity of 40 mm/hour it only takes about 2 hours to reach peak concentrations lower than 0.1 mg/L, at 0.3 mm/hour it takes about 10 hours to reach peak concentrations of 1.3, 0.9, 5.2 and 1.1 mg/L for terbutryn from Emalux paint, terbutryn from Südwest paint, carbendazim from Emalux paint, and carbendazim from MIPA paint, respectively. The results confirm that biocides leached from roof paint will be present in roof runoff. The highest estimated peak concentrations are close to the water solubility of the respective biocides. This indicates that the model assumption of a concentration independent leaching rate will tendentially lead to an overestimation of the leached concentrations under these circumstances. However, under most circumstances such as higher rain intensities, and longer time after peak concentrations have been reached, the runoff concentrations are far from the solubility limit, and therefore it is proposed that the model assumptions are tenable. The leaching of biocides from roof paints can be roughly assessed using a relatively simple approach. The declaration of biocidal ingredients in roof paints should be improved and information on their biocide leaching behaviour should be made available. Furthermore, the estimations should be evaluated by a field study. The leaching study indicated that the concentrations of selected biocides can reach significant levels, especially after low intensity rainfall. Taking into account the inherent biological activity of the substances under scrutiny, it can already be concluded that it is not advisable to use runoff water from roofs freshly painted with biocide containing roof paints. These results have been complemented by a literature search of biological effects of the investigated biocides, ecotoxicological tests with several species and a risk analysis for organisms exposed to runoff water. This will be presented in Part 2 of this contribution.

• Lipophilicity parameters for ionic liquid cations and their correlation to in vitro cytotoxicity.

  Authors: Johannes Ranke, Anja Müller, Ulrike Bottin-Weber, Frauke Stock, Stefan Stolte, Jürgen Arning, Reinhold Störmann, Bernd Jastorff

  Ecotoxicology and environmental safety. 08/2007; 67(3):430-8.

  Regarding the great structural variability of the currently expanding group of ionic liquids, it is highly desirable to understand the basic factors affecting their toxicity in different biologicalRegarding the great structural variability of the currently expanding group of ionic liquids, it is highly desirable to understand the basic factors affecting their toxicity in different biological systems. The present study of a set of 74 ionic liquids with imidazolium, pyrrolidinium, pyridinium, quinolinium, quaternary phosphonium and quaternary ammonium cations and the comparatively small anions Cl(-), Br(-), BF(4)(-), or PF(6)(-) demonstrates the influence of the cation lipophilicity on the cytotoxicity in IPC-81 leukemia cells from rats. The scope of this correlation is limited to ionic liquids with these or similarly small anions that are sufficiently nonreactive under physiological and chromatographic conditions and whose cation lipophilicity does not exceed a certain threshold.

• Progress in evaluation of risk potential of ionic liquids—basis for an eco-design of sustainable products

  Authors: Bernd Jastorff, Kerstin Mölter, Peter Behrend, Ulrike Bottin-Weber, Juliane Filser, Anna Heimers, Bernd Ondruschka, Johannes Ranke, Maike Schaefer, Heike Schröder, Annegret Stark, Piotr Stepnowski, Frauke Stock, Reinhold Störmann, Stefan Stolte ...

  Green Chemistry. 01/2005; 7:362-372.

  Motivated by the prevailing need for a sustainable development and taking the principles of Green Chemistry as a starting point, the present paper describes new and updated findings regarding aMotivated by the prevailing need for a sustainable development and taking the principles of Green Chemistry as a starting point, the present paper describes new and updated findings regarding a sustainable product design for ionic liquids. The focus is on environmental risk. Nevertheless, cytotoxicity testing and first indicative results from a genotoxicity study extend present knowledge also with regard to possible effects on humans. The structural variability of commercially available ionic liquids as well as the abundance of theoretically accessible ionic liquids is illustrated and the consequences for an integrated risk assessment accompanying the development process are discussed. The side chain effect on toxicity for imidazolium type ionic liquids was confounded by more complex biological testing. Also, an influence of an anion on cytotoxicity is shown for the first time. Testing of presumed metabolites of the imidazolium type cations showed a significantly lower biological activity in cytotoxicity studies than their parent compounds. The importance of a purity assessment for ionic liquids is pointed out and a collection of methods that is believed to be adequate is presented. In addition to risk analysis, the use of life cycle analysis for the multi-objective problem of designing ionic liquids is sketched and an eco-design scheme for ionic liquids is proposed. In conclusion, the paper illustrates the complex nature of the development processes ionic liquids are currently undergoing and provides guidance on which aspects have to be kept in mind.

• Reversed-phase liquid chromatographic method for the determination of selected room-temperature ionic liquid cations.

  Authors: Piotr Stepnowski, Anja Müller, Peter Behrend, Johannes Ranke, Jens Hoffmann, Bernd Jastorff

  Journal of chromatography. A. 05/2003; 993(1-2):173-8.

  The separation of selected 1-alkyl- and 1-aryl-3-methylimidazolium-based room temperature ionic liquid cations has been performed using reversed-phase high-performance liquid chromatography withThe separation of selected 1-alkyl- and 1-aryl-3-methylimidazolium-based room temperature ionic liquid cations has been performed using reversed-phase high-performance liquid chromatography with electrospray ionization mass detection. The RP-HPLC method development started with the selection of a column taking into account especially the resolution of low molecular congeners of the selected group. Mobile phase composition was optimized for peak resolution, sensitivity and high reproducibility of retention values. The results of the method development were applied to the determination of exemplary ionic liquid species present in the medium used in cytotoxicity studies.

• How hazardous are ionic liquids? Structure–activity relationships and biological testing as important elements for sustainability evaluation

  Authors: Bernd Jastorff, Reinhold Störmann, Johannes Ranke, Kerstin Mölter, Frauke Stock, Boris Oberheitmann, Wolfgang Hoffmann, Jens Hoffmann, Matthias Nüchter, Bernd Ondruschka, Juliane Filser

  Green Chemistry. 01/2003; 5:136-142.

  For ionic liquids only few toxicological and/or ecotoxicological data are available until now. A strategy is presented which aims at an environmental risk assessment of chemicals, using a combinationFor ionic liquids only few toxicological and/or ecotoxicological data are available until now. A strategy is presented which aims at an environmental risk assessment of chemicals, using a combination of structure–activity relationships (SAR), toxicological and ecotoxicological tests and modelling. The parts “test-kit-concept” and “multidimensional risk analysis” are described in detail by means of selected imidazolium ionic liquids. The iterative process of this strategy offers a tool for sustainable product design.

• Persistence of antifouling agents in the marine biosphere.

  Authors: Johannes Ranke

  Environmental science & technology. 05/2002; 36(7):1539-45.

  Risk indicators provide an interesting way to compare chemical substances with respect to the risks of their large-scaled release. The present study implies that, for antifouling agents used inRisk indicators provide an interesting way to compare chemical substances with respect to the risks of their large-scaled release. The present study implies that, for antifouling agents used in commercial shipping, residence times in the marine biosphere are especially suitable to represent their inherent potential to cause exposure of organisms. A simple box model is described providing the possibility to estimate residence times in the marine biosphere from water-particle equilibrium partitioning constants and half-lives in water and sediment. Resulting residence times in the marine biosphere range from about 5 d (4,5-dichloro-2-n-octyl-4-isothiazolin-3-one) up to about 40,000 yr (copper). For an evaluation of the validity of the model, calculated values are compared with measured environmental concentrations. Remaining uncertainties are also discussed. The main purpose of the presented residence times is to serve as a basis for decisions in antifouling paint development or environmentally conscious purchasing of antifouling paints.

• Micelle formation of imidazolium ionic liquids in aqueous solution

  Authors: Christian Jungnickel, Justyna Łuczak, Johannes Ranke, José F. Fernández, Anja Müller, Jorg Thöming

  Colloids and Surfaces A: Physicochemical and Engineering Aspects.

  Ionic liquids (ILs) form a new class of compounds with a much varied industrial and technological application. Some research has been conducted in ecotoxicity of these compounds, but very little isIonic liquids (ILs) form a new class of compounds with a much varied industrial and technological application. Some research has been conducted in ecotoxicity of these compounds, but very little is known about their structure in aqueous solutions. It is known that some ionic liquids can form aggregates in aqueous solution. To determine how such structures influence the use, distribution and toxicity of ILs, first the critical micelle concentrations of the ILs need to be determined. Therefore the critical micelle concentration (CMC) for a number of imidazolium ionic liquids was determined in aqueous solution. The expected dependency of the CMC on the length of the alkyl chain of the investigated 1-alkyl-3-methylimidazolium ILs was shown. The degree of ionization and the energy of aggregation were calculated and related to the alkyl chain length of the imidazolium. A significant correlation between retention times in reversed phase gradient HPLC, and the pCMC was observed. It was also shown that the CMC is directly related to the lipophilicity of the cation.

• Reconsidering environmental effects assessment of chemicals: Proposal for a dynamic testing strategy

  Authors: Marion Junghans, Maike Schaefer, Wiebke Drost, Enken Hassold, Frauke Stock, Matthias Dünne, Tanja Juffernholz, Wiebke Meyer, Johannes Ranke

  Basic and Applied Ecology.

  Certain substances may be hazardous to ecosystems. To be able to preserve the structures and functions of ecosystems, knowledge is required to qualify and quantify such hazards. To this end, biotestsCertain substances may be hazardous to ecosystems. To be able to preserve the structures and functions of ecosystems, knowledge is required to qualify and quantify such hazards. To this end, biotests are indispensable tools. For the development and/or choice of biotests, special attention has to be drawn to conflicts between scientific demands and practical constraints. From a purely scientific point of view, experiments should be designed to maximise the ecological relevance of the obtained results. However, this often collides with the limited resources (budget, time, manpower) available. Furthermore, societal issues (e.g. animal welfare) have to be taken into account. Thus, it is necessary to develop a scientifically sound testing approach that avoids unnecessary animal testing, keeps the costs low, and can be performed within a short timeframe. The different perspectives of ecology, environmental toxicology, and environmental chemistry should be integrated into a balanced ecotoxicological approach. Accordingly, we propose a dynamic testing strategy, which is adapted to the substance (or substance group) in question and its mode(s) of action.ZusammenfassungBestimmte chemische Substanzen können eine Gefahr für Ökosysteme darstellen. Für den Schutz der Strukturen und Funktionen in Ökosystemen, müssen diese Gefahren qualifiziert und quantifiziert werden. Biotests liefern dafür die entscheidenden Ergebnisse. Für die Entwicklung und/oder Wahl solcher Biotests, muss den Konflikten zwischen wissenschaftlichen Ansprüchen und praktischen Beschränkungen besondere Aufmerksamkeit geschenkt werden. Aus rein wissenschaftlicher Sicht sollten die Experimente so gestaltet sein, dass die ökologische Relevanz der Ergebnisse maximiert wird. Dies stösst jedoch häufig an die Grenzen der verfügbaren Ressourcen (Budget, Zeit, Arbeitskraft). Zusätzlich müssen gesellschaftliche Aspekte berücksichtigt werde (z.B. der Tierschutz). Daher ist es notwendig, einen wissenschaftlich stimmigen Test-Ansatz zu wählen, der unnötige Tierversuche vermeidet, die Kosten gering hält und innerhalb kurzer Zeit durchgeführt werden kann. Die unterschiedlichen Aspekte von Ökologie, Umwelttoxikologie und Umweltchemie sollten zu einem ausgewogenen ökotoxikologischen Ansatz zusammengeführt werden. Daher schlagen wir eine dynamische Teststrategie vor, welche sich an die jeweilige Substanz (oder Substanzgruppe) und ihre Wirkmechanismen anpasst.