An ARXPS and ERXPS study of quaternary ammonium and phosphonium ionic liquids: utilising a high energy Ag Lα’ X-ray source

IntroductionIonic liquid (IL) surface science has experienced rapid expansion in recent years. As such, a multitude of ultra-high vacuum (UHV) techniques have been used to probe the IL/vacuum interface including laboratory and synchrotron X-ray photoelectron spectroscopy (XPS), metastable impact electron spectroscopy (MIES), low energy ion scattering (LEIS), Rutherford backscattering (RBS) and neutral impact collision ion scattering spectroscopy (NICISS). To date, the vast majority of these studies have focused upon cyclic nitrogen-containing cations, particularly the 1-alkyl-3-methylimidazolium family, whereas acyclic cations including tetraalkylammonium and –phosphonium have been overlooked despite their potential use in a wide range of existing applications including heterogeneous catalysis, gas capture/separation, and nanoparticle formation

Experimental measurement and prediction of ionic liquid ionisation energies

Ionic liquid (IL) valence electronic structure provides key descriptors for understanding and predicting IL properties. The ionisation energies of 60 ILs are measured and the most readily ionised valence state of each IL (the highest occupied molecular orbital, HOMO) is identified using a combination of X-ray photoelectron spectroscopy (XPS) and synchrotron resonant XPS. A structurally diverse range of cations and anions were studied. The cation gave rise to the HOMO for nine of the 60 ILs presented here, meaning it is energetically more favourable to remove an electron from the cation than the anion. The influence of the cation on the anion electronic structure (and vice versa) were established; the electrostatic effects are well understood and demonstrated to be consistently predictable. We used this knowledge to make predictions of both ionisation energy and HOMO identity for a further 516 ILs, providing a very valuable dataset for benchmarking electronic structure calculations and enabling the development of models linking experimental valence electronic structure descriptors to other IL properties, e.g. electrochemical stability. Furthermore, we provide design rules for the prediction of the electronic structure of ILs

Exploring ionic liquids based on pyrrolidinium and imidazolium cations with low toxicity towards Escherichia coli for designing sustainable bioprocesses

Ionic liquids (ILs) are widely applied in many bioprocesses involving microorganisms due to their unique properties. In this work, the toxicity of imidazolium and pyrrolidinium ionic liquids towards E. coli., a bacterium for which there are limited toxicity data in the literature, was determined. For its simplicity, the nephelometry method was used to estimate ionic liquid toxicity values. The influence of the cation and the alkyl chain length of the cation and anion was analysed. Pyrrolidinium cations were seen to be less toxic than imidazolium cations, while an increase in the alkyl chain length of both pyrrolidinium and imidazolium cations increased the toxicity. Among the anions studied, dimethylphosphate ([Me2PO4]) was the less toxic, while the EC50 for the ionic liquid 1-butyl-3-methylpyrrolidinium dimethylphosphate ([C1C4Pyr][Me2PO4]) was close to 200 mM. Furthermore, a dicationic ionic liquid based on imidazolium and pyrrolidinium cations was synthetized and its toxicity toward E. coli was analysed, maintaining a growth rate of 100% in the range 0-0.76 mM. The methodology used in this work allows to easily find the less toxic ionic liquids that are biocompatible with E. coli to be used in new bioprocesses

Thermolysis of Organofluoroborate Ionic Liquids to NHC-Organofluoroborates

A range of dialkylimidazolium organotrifluoroborate ionic liquids were prepared by anion metathesis from newly available potassium organotrifluoroborate salts, and their physical properties were characterized by TGA, DSC, and STA. Thermal decomposition was subsequently investigated under vacuum with direct insertion mass spectrometry to determine whether thermolysis was a viable route to prepare N-heterocyclic carbene organofluoroborates, which are an important class of emerging compounds. Several key targets were identified, which highlighted the potential to shortcut complex synthetic methodologies otherwise required to access such molecules

Continuous-Flow Alkene Metathesis: The Model Reaction of 1-Octene Catalyzed by Re2O7/alfa-Al2O3 with Supercritical CO2 as a Carrier

In the presence of Re2O7 supported on γ-Al2O3, the self-metathesis of 1-octene was conveniently carried out under continuous-flow (CF) conditions using supercritical CO2 (scCO2) as a carrier. This investigation allowed optimization of reaction parameters, the best values of which were found to be 100 °C and 90 bar, operating at flow rates of 0.05 and 1 mL min−1 for 1-octene and scCO2, respectively, the reaction proceeded with very good self-metathesis selectivity (>90%) and an average productivity of ∼0.24 mL tetradecene gRe −1 min−1 . Although the catalyst was completely deactivated after the first 100–150 min of reaction, it could be recycled for (at least) five subsequent reactions without any loss of performance. The results provided incontrovertible evidence that for the investigated reaction, scCO2was a superior carrier with respect to conventional liquids, such as toluene or n-hexane

Halometallate ionic liquids: thermal properties, decomposition pathways, and life cycle considerations

Halometallate ionic liquids provide new opportunities for industrial catalytic processes because of their unique blend of physical and chemical properties. Tunability underpins the success of ionic liquids because small structural changes can have drastic effects on either property. Catalysis can be optimised by adjusting structures to target properties such as Lewis basicity and acidity, but the structural changes have simultaneous impacts on physical properties. In this work, we provide a thorough, methodical, and reliable list of thermal parameters to help define temperature limits to prevent catalyst poisoning and limit the need to replace costly and environmentally demanding solvents. Mechanistic insights show that decomposition is particularly detrimental for halometallate ionic liquids, and life cycle analysis highlights that lower levels of organic cations are better for economic and environmental sustainability

Remote-controlled experiments with cloud chemistry

Developing cleaner chemical processes often involves sophisticated flow-chemistry equipment that is not available in many economically developing countries. For reactions where it is the data that are important rather than the physical product, the networking of chemists across the internet to allow remote experimentation offers a viable solution to this problem

People and Things on the Move: Domestic Material Culture, Poverty and Mobility in Victorian London

© 2016, The Author(s). The development of what Mayne and Lawrence (Urban History 26: 325–48, 1999) termed “ethnographic” approaches to studying nineteenth-century households and urban communities has gathered momentum in recent years. As such research agendas have taken hold and been applied to new contexts, so critiques, methodological developments, and new intellectual and theoretical currents, have provided opportunities to enhance and develop approaches. This article contributes to this on-going process. Drawing upon household archaeological research on Limehouse, a poor neighborhood in Victorian London, and inspired by the theoretical insights provided by the “new mobilities paradigm,” it aims to place “mobility” as a central and enabling intellectual framework for understanding the relationships between people, place, and poverty. Poor communities in nineteenth-century cities were undeniably mobile and transient. Historians and archaeologists have often regarded this mobility as an obstacle to studying everyday life in such contexts. However, examining temporal routines and geographical movements across a variety of time frames and geographical scales, this article argues that mobility is actually key to understanding urban life and an important mechanism for interpreting the fragmented material and documentary traces left by poor households in the nineteenth-century metropolis.We are grateful to the UK’s Arts and Humanities Research Council who funded the research upon which this paper is based (Grant Reference AH/E002285/1): ‘Living in Victorian London: Towards a Material History of Everyday Domestic Life in the Nineteenth-Century Metropolis

Mind your step: the effects of mobile phone use on gaze behavior in stair climbing

Stair walking is a hazardous activity and a common cause of fatal and non-fatal falls. Previous studies have assessed the role of eye movements in stair walking by asking people to repeatedly go up and down stairs in quiet and controlled conditions, while the role of peripheral vision was examined by giving participants specific fixation instructions or working memory tasks. We here extend this research to stair walking in a natural environment with other people present on the stairs and a now common secondary task: Using one's mobile phone. Results show that using the mobile phone strongly draws one's attention away from the stairs, but that the distribution of gaze locations away from the phone is little influenced by using one's phone. Phone use also increased the time needed to walk the stairs, but handrail use remained low. These results indicate that limited foveal vision suffices for adequate stair walking in normal environments, but that mobile phone use has a strong influence on attention, which may pose problems when unexpected obstacles are encountered