Molecular structures and electronic transitions of 3,6-Diphenyl-1,2-dithiin and its radical cation: a spectroelectrochemical and DFT study

One-electron oxidation of 3,6-diphenyl-1,2-dithiin yields the corresponding radical cation. The product is stable at low temperatures and can be distinguished by a triplet EPR signal. Cyclic voltammetric, UV-vis spectroelectrochemical, and DFT studies were performed to elucidate its molecular structure and electronic properties. Time-dependent DFT calculations reproduce appreciably well the UV-vis spectral changes observed during the oxidation. The results reveal a moderately twisted structure of the 1,2-dithiin heterocycle in the radical cation.

Peroxy radical partitioning during the AMMA radical intercomparison exercise

Peroxy radicals were measured onboard two scientific aircrafts during the AMMA (African Monsoon Multidisciplinary Analysis) campaign in summer 2006. This paper reports results from the flight on 16 August 2006 during which measurements of HO2 by laser induced fluorescence spectroscopy at low pressure (LIF-FAGE) and total peroxy radicals (RO2* = HO2+ΣRO2, R = organic chain) by two similar instruments based on the peroxy radical chemical amplification (PeRCA) technique were subject of a blind intercomparison. The German DLR-Falcon and the British FAAM-BAe-146 flew wing tip to wing tip for about 30 min making concurrent measurements on 2 horizontal level runs at 697 and 485 hPa over the same geographical area in Burkina Faso. A full set of supporting measurements comprising photolysis frequencies, and relevant trace gases like CO, NO, NO2, NOy, O3 and a wider range of VOCs were collected simultaneously. Results are discussed on the basis of the characteristics and limitations of the different instruments used. Generally, no data bias are identified and the RO2* data available agree quite reasonably within the instrumental errors. The [RO2*]/[HO2] ratios, which vary between 1:1 and 3:1, as well as the peroxy radical variability, concur with variations in photolysis rates and in other potential radical precursors. Model results provide additional information about dominant radical formation and loss processes.

Photopolymerization of Pluronic F127 diacrylate: a colloid-templated polymerization

Pluronic F127 diacrylate (F127DA) is a bifunctional acrylate and as such it should in principle produce macroscopically cross-linked materials; however, its photopolymerization in water does not lead to 3D-extended hydrogels. The main species present after photopolymerization appear to be cross-linked micelles, which indicates that the micellar morphology of F127DA has a template effect on the polymerization. The structural analogy causes the physical state of precursor and polymerized materials to be very similar for a wide range of concentrations (5–25% wt) and temperatures (10–37 °C). Also the long-range morphology of F127DA appears to have a template effect: samples photopolymerized in a micellar gel state and redispersed at high concentration (25% wt) show a long-range organization that depended on the concentration and therefore on the order of the precursor.

Electron spin resonance study of puff-resolved free radical formation in mainstream cigarette smoke

Puff-by-puff resolved gas phase free radicals were measured in mainstream smoke from Kentucky 2R4F reference cigarettes using ESR spectroscopy. Three spin-trapping reagents were evaluated: PBN, DMPO and DEPMPO. Two procedures were used to collect gas phase smoke on a puff-resolved basis: i) the accumulative mode, in which all the gas phase smoke up to a particular puff was bubbled into the trap (i.e., the 5th puff corresponded to the total smoke from the 1st to 5th puffs). In this case, after a specified puff, an aliquot of the spin trap was taken and analysed; or, ii) the individual mode, in which the spin trap was analysed and then replaced after each puff. Spin concentrations were determined by double-integration of the first derivative of the ESR signal. This was compared with the integrals of known standards using the TEMPO free radical. The radicals trapped with PBN were mainly carbon-centred, whilst the oxygen-centred radicals were identified with DMPO and DEPMPO. With each spin trap, the puff-resolved radical concentrations showed a characteristic pattern as a function of the puff number. Based on the spin concentrations, the DMPO and DEPMPO spin traps showed better trapping efficiencies than PBN. The implication for gas phase free radical analysis is that a range of different spin traps should be used to probe complex free radical reactions in cigarette smoke.

π-dimerization of pleiadiene radical cations at low temperatures revealed by UV–vis spectroelectrochemistry and quantum theory

One-electron oxidation of the non-alternant polycyclic aromatic hydrocarbon pleiadiene and related cyclohepta[ c,d]pyrene and cyclohepta[c,d]fluoranthene in THF produces corresponding radical cations detectable in the temperature range of 293–263 K only on the subsecond time scale of cyclic voltammetry. Although the EPR-active red-coloured pleiadiene radical cation is stable according to the literature in concentrated sulfuric acid, spectroelectrochemical measurements reported in this study provide convincing evidence for its facile conversion into the green-coloured, formally closed shell and, hence, EPRsilent π-bound dimer dication stable in THF at 253 K. The unexpected formation of the thermally unstable dimeric product featuring a characteristic intense low-energy absorption band at 673 nm (1.84 eV; logεmax=4.0) is substantiated by ab initio calculations on the parent pleiadiene molecule and the PF6 − salts of the corresponding radical cation and dimer dication. The latter is stabilized with respect to the radical cation by 14.40 kcal mol−1 (DFT B3LYP) [37.64 kcal mol−1 (CASPT2/DFT B3LYP)]. An excellent match has been obtained between the experimental and TDDFT- calculated UV–vis spectra of the PF6 − salt of the pleiadiene dimer dication, considering solvent (THF) effects.

Simultaneous bridge-localized and mixed-valence character in diruthenium radical cations featuring diethynylaromatic bridging ligands

A series of bimetallic ruthenium complexes [{Ru(dppe)Cp*}2(μ-C≡CArC≡C)] featuring diethynylaromatic bridging ligands (Ar = 1,4-phenylene, 1,4-naphthylene, 9,10-anthrylene) have been prepared and some representative molecular structures determined. A combination of UV–vis–NIR and IR spectroelectrochemical methods and density functional theory (DFT) have been used to demonstrate that one-electron oxidation of compounds [{Ru(dppe)Cp*}2(μ-C≡CArC≡C)](HC≡CArC≡CH = 1,4-diethynylbenzene; 1,4-diethynyl-2,5-dimethoxybenzene; 1,4-diethynylnaphthalene; 9,10-diethynylanthracene) yields solutions containing radical cations that exhibit characteristics of both oxidation of the diethynylaromatic portion of the bridge, and a mixed-valence state. The simultaneous population of bridge-oxidized and mixed-valence states is likely related to a number of factors, including orientation of the plane of the aromatic portion of the bridging ligand with respect to the metal d-orbitals of appropriate π-symmetry.

Haldane's Mackindergarten: a radical experiment in British military education

This article critically evaluates a course that was conceived and run at the LSE by Sir Halford Mackinder for officers of the Britsh Army between 1907 and 1932.There is an examination of the nature of the syllabus,the aims and objectives of this course.An explanation is also given as to why the army cut it seven years before the outbreak of the Second World War.

Arabidopsis annexin1 mediates the radical-activated plasma membrane Ca2+ - and K+ -permeable conductance in root cells

Plant cell growth and stress signaling require Ca2+ influx through plasma membrane transport proteins that are regulated by reactive oxygen species. In root cell growth, adaptation to salinity stress, and stomatal closure, such proteins operate downstream of the plasma membrane NADPH oxidases that produce extracellular superoxide anion, a reactive oxygen species that is readily converted to extracellular hydrogen peroxide and hydroxyl radicals, OH_. In root cells, extracellular OH_ activates a plasma membrane Ca2+-permeable conductance that permits Ca2+ influx. In Arabidopsis thaliana, distribution of this conductance resembles that of annexin1 (ANN1). Annexins are membrane binding proteins that can form Ca2+-permeable conductances in vitro. Here, the Arabidopsis loss-of-function mutant for annexin1 (Atann1) was found to lack the root hair and epidermal OH_-activated Ca2+- and K+-permeable conductance. This manifests in both impaired root cell growth and ability to elevate root cell cytosolic free Ca2+ in response to OH_. An OH_-activated Ca2+ conductance is reconstituted by recombinant ANN1 in planar lipid bilayers. ANN1 therefore presents as a novel Ca2+-permeable transporter providing a molecular link between reactive oxygen species and cytosolic Ca2+ in plants.

Color adjectives and radical contextualism

Radical contextualists have observed that the content of what is said by the utterance of a sentence is shaped in far-reaching ways by the context of utterance. And they have argued that the ways in which the content of what is said is shaped by context cannot be explained by semantic theory. A striking number of the examples that radical contextualists use to support their view involve sentences containing color adjectives (“red”, “green”, etc.). In this paper, I show how the most sophisticated analysis of color adjectives within the explanatory framework of compositional truth conditional semantics—recently developed by Kennedy and McNally (Synthese 174(1):79–98 2010)—needs to be modified to handle the full range of contextual variation displayed by color adjectives.

The paradox of nationalism: the common denominator of radical right and radical left euroscepticism

What can explain the strong euroscepticism of radical parties of both the right and the left? This article argues that the answer lies in the paradoxical role of nationalism as a central element in both party families, motivating opposition towards European integration. Conventionally, the link between nationalism and euroscepticism is understood solely as a prerogative of radical right-wing parties, whereas radical left-wing euroscepticism is associated with opposition to the neoliberal character of the European Union.This article contests this view. It argues that nationalism cuts across party lines and constitutes the common denominator of both radical right-wing and radical left-wing euroscepticism. It adopts a mixed-methods approach, combining intensive case study analysis with quantitative analysis of party manifestos. First, it traces the link between nationalism and euroscepticism in Greece and France in order to demonstrate the internal validity of the argument. It then undertakes a cross-country statistical estimation to assess the external validity of the argument and its generalisability across Europe.

The civic zeitgeist: nationalism and liberal values in the European radical right

This article examines the relationship between nationalism and liberal values, and more specifically the redefinition of boundaries between national communities and others in the rhetoric of radical right parties in Europe. The aim is to examine the tension between radical right party discourse and the increasing need to shape this discourse in liberal terms. We argue that the radical right parties that successfully operate within the democratic system tend to be those best able to tailor their discourse to the liberal and civic characteristics of national identity so as to present themselves and their ideologies as the true authentic defenders of the nation's unique reputation for democracy, diversity and tolerance. Comparing the success of a number of European radical right parties ranging from the most electorally successful SVP to the more mixed BNP, FN and NPD, we show that the parties that effectively deploy the symbolic resources of national identity through a predominantly voluntaristic prism tend to be the ones that fare better within their respective political systems. In doing so, we challenge the conventional view in the study of nationalism which expects civic values to shield countries from radicalism and extremism.

Radical Conservatism

In 1938, Yugoslav sculptor Oscar Nemon arrived in Britain, having fled the Nazi invasion of Brussels, where he was living with Magritte. He was part of the European avant-garde that came to the UK as a refugee. Shortly thereafter, Nemon proposed a bold architectural plan to construct a temple of universal ethics in London and was in correspondence over this with central figures in Britain. After the war, he became know for his portrayal of figures like Churchil, culminating in a bust of Margaret Thatcher that is currently at the Tory HQ. Shown at Castlefield Gallery in 2013-2014, Radical Conservatism was an exhibition that explored the space between these two moments and asked whether these two terms are really antithetical. In the British context in particular, where the European avant-garde never really took hold, a kind of reactionary modernism has always defined a culture wary of revolution. But today more than ever, with the left increasingly holding on to the past of the welfare state as an ideal, and the right quietly revolutionising our world through neoliberal reforms, the paradigms of radicalism and conservatism need to be redefined. Can conservatism be seen as a radical position in itself? If art is defined by a movement towards the new - could 'holding on to the past' stubbornly be seen as a critical position, now that neo-liberalism has forced a far more radical shift in politics than the left has managed in a long time? Curated by Pil and Galia Kollectiv, featuring work by Chris Evans, IRWIN, Pil and Galia Kollectiv, Joseph Lewis, Patrick Moran, Oscar Nemon and Public Movement and a symposium with contributions from Professor Alun Rowlands and Robert Garnett.

The kinetics of the gas-phase reactions of selected monoterpenes and cyclo-alkenes with ozone and the NO3 radical

The relative rate method has been used to measure the room-temperature rate constants for the gasphase reactions of ozone and NO3 with selected monoterpenes and cyclo-alkenes with structural similarities to monoterpenes. Measurements were carried out at 298 ! 2 K and 760 ! 10 Torr. The following rate constants (in units of 10"18 cm3 molecule"1 s"1) were obtained for the reaction with ozone: methyl cyclohexene (132 ! 17), terpinolene (1290 ! 360), ethylidene cyclohexane (223 ! 57), norbornene (860 ! 240), t-butyl isopropylidene cyclohexane (1500 ! 460), cyclopentene (543 ! 94), cyclohexene (81 ! 18), cyclooctene (451 ! 66), dicyclopentadiene (1460 ! 170) and a-pinene (107 ! 13). For the reaction with NO3 the rate constants obtained (in units of 10"12 cm3 molecule"1 s"1) were: methyl cyclohexene (7.92 ! 0.95), terpinolene (47.9 ! 4.0), ethylidene cyclohexane (4.30 ! 0.24), norbornene (0.266 ! 0.029), cyclohexene (0.540 ! 0.017), cyclooctene (0.513 ! 0.029), dicyclopentadiene (1.20 ! 0.10) and a-pinene (5.17 ! 0.62). Errors are quoted as the root mean square of the statistical error (95% con!dence) and the quoted error in the rate constant for the reference compound. Combining these results with previous studies, new recommendations for the rate constants are presented. Molecular orbital energies were calculated for each alkene and the kinetic data are discussed in terms of the deviation from the structureeactivity relationship obtained from the rate constants for a series of simple alkenes. Lifetimes with respect to key initiators of atmospheric oxidation have been calculated suggesting that the studied reactions play dominant roles in the night-time removal of these compounds from the atmosphere.

Radical cations of end-capped tetrathienoacenes and their p-dimerization controlled by the nature of a-substituents and counterion concentration

Radical cations of a soluble rigid tetrathienoacene are capable of forming stable p-dimer dications at ambient temperature when the short backbone becomes extended with conjugated thiophene-2-yl substituents in the a-positions. On the other hand, simple attachment of methyl groups on the a-carbon of the external thiophen-2-yl rings proved sufficient to inhibit the dimerization. Stable radical cationswere also exclusively formed for tetrathienoacene derivatives end-capped with bulky TIPS and phenyl substituents.