Cover Picture: Counterion-Induced Inversion of Conformer Stability of a [5]Helquat Dication (ChemPlusChem 8/2012)

Authors

  • Lukáš Severa,

    1. Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo náměstí 2, 16610 Prague 6 (Czech Republic)
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  • Michael Jirásek,

    1. Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo náměstí 2, 16610 Prague 6 (Czech Republic)
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  • Pavel Švec,

    1. Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo náměstí 2, 16610 Prague 6 (Czech Republic)
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  • Dr. Filip Teplý,

    Corresponding author
    1. Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo náměstí 2, 16610 Prague 6 (Czech Republic)
    • Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo náměstí 2, 16610 Prague 6 (Czech Republic)
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  • Dr. Ágnes Révész,

    1. Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo náměstí 2, 16610 Prague 6 (Czech Republic)
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  • Dr. Detlef Schröder,

    Corresponding author
    1. Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo náměstí 2, 16610 Prague 6 (Czech Republic)
    • Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo náměstí 2, 16610 Prague 6 (Czech Republic)
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  • Dr. Dušan Koval,

    1. Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo náměstí 2, 16610 Prague 6 (Czech Republic)
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  • Dr. Václav Kašička,

    1. Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo náměstí 2, 16610 Prague 6 (Czech Republic)
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  • Dr. Ivana Císařová,

    1. Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 12843 Prague 2 (Czech Republic)
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  • Dr. David Šaman

    1. Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo náměstí 2, 16610 Prague 6 (Czech Republic)
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Abstract

original image

The cover picture shows different approaches used by chemists in Prague to investigate the conformations of a pentacyclic bispyridinium ion in the gas phase, in solution, and in the solid state. The title heterocycle has two conformers of which one is helical (helquat, HQ2+) and the other looks like a horse-saddle (saddlequat, SQ2+). For the free dication in the gas phase, the neutral salt in solution, and the crystal, the helical form is preferred. However, in the singly charged binary ion pairs [HQ2+ ⋅ X] and [SQ2+ ⋅ X], subtle effects of the counterions X determine the relative stabilities of conformers, and with several counterions the saddle forms are in fact more stable than the helical ones. A full account can be found in the Full Paper by D. Schröder and co-workers on page 624 ff.

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