1. V. Čermák Laboratory, J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, 18223 Prague 8, Czech Republic, Department of Organic Chemistry, Faculty of Sciences, Charles University in Prague, Hlavova 8, 12843 Prague 2, Czech Republic and Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 16610 Prague 6, Czech Republic