28 research outputs found

    Termolecular proton transfer reactions assisted by ionic hydrogen bond formation: Reactions of aromatic cations with polar molecules

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    We present a new method that applies resonantโ€twoโ€photon ionization to generate reactant ions selectively in the source of a highโ€pressure mass spectrometer (R2PIโ€HPMS) for kinetic and equilibrium studies. Applications to reactions that would be obscured otherwise in a complex system are illustrated in mixtures of benzene with polar solvent molecules (S). We observe a novel type of proton transferreactions from C6H6 +โ€ข to two S molecules where S=CH3CN, CH3OH, C2H5OH and CH3COOC2H5, and from C6H5CH3 +โ€ข to two S molecules where S=CH3OH and C2H5OH to form protonated solvent S2H+ dimers. The reactions are driven by the strong hydrogen bonds in the S2H+ dimers and therefore require the formation of the hydrogen bond concertedly with proton transfer, to make the process energetically feasible. The adducts (C6H6 +โ€ข)S are observed with blocked solvent molecules where the subsequent switching reaction to yield S2H+ is slow, but not with alcohol reactants that can form hydrogenโ€bonded chains that facilitate fast subsequent proton extraction. Correspondingly, kinetic simulations suggest that the mechanism proceeds through (C6H6 +โ€ข)S+Sโ†’S2H++C6H5 โ€ข and C6H6 +โ€ข+2Sโ†’S2H++C6H5 โ€ขreactions, respectively. The rate coefficients of these reactions are in the range 10โˆ’13โˆ’10โˆ’12 cm3โ€‰sโˆ’1 for the reaction through a bimolecular switching channel and in the range 10โˆ’26โˆ’10โˆ’28 cm6โ€‰sโˆ’1 for reaction through a direct termolecular proton extraction mechanism. The relation to energetics and reactant structure is examined

    The Anatomy of Memory Politics: A Formalist Analysis of Tate Britainโ€™s โ€˜Artist and Empireโ€™ and the Struggle over Britainโ€™s Imperial Past

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    In this paper, I propose a new approach for understanding the meaning of memory politics, which draws upon the archetypal literary criticism of Northrop Frye. I suggest that the four archetypes elaborated by Fryeโ€”comedy, romance, tragedy, and satireโ€”can be used as a heuristic device for interpreting the contested historical narratives that are associated with the politics of memory. I illustrate this approach through a case-study of Artists and Empire: Facing Britainโ€™s Imperial Past, an exhibition held at Tate Britain in 2016, amidst increasing contestation over the meaning of the British Empire. In sum, I find that the exhibit narrated Britainโ€™s imperial past as a comedy, in which a key theme was the progressive cultural mixing of the British and the people they colonized. To conclude, I discuss the implications of such a narrative for constructing an inclusive, postcolonial British identity. As an alternative, I draw on Aristotle to suggest that a tragic narrative would have been more propitious
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