Quantitative evaluation of the chloride template effect in the formation of dicationic [1(4)]imidazoliophanes.
The formation of macrocycles containing two imidazolium rings such as 1.2X and 2.2X is anion-directed through hydrogen bonding. The template effect exerted by the chloride anion in the ring-closure reaction of the monocationic model intermediate 9+ to yield the [1(4)]imidazoliophane 2(2+) has been evaluated. This effect was quantified following the kinetics of the macrocyclization by using a UV-vis technique. The rate of the ring closure of monocation 9+ is increased up to 10 times, in the presence of Bu4NCl 0.04 M. This finding confirms that the template effect is operative in the macrocyclization leading to dicationic [1(4)]imidazoliophanes.
Ramos
Susana
S
Dipartimento di Chimica e CNR-ICCOM-Sezione di Roma, Università di Roma "La Sapienza", P.le Aldo Moro, 2, 00185 Roma, Italy.
Alcalde
Ermitas
E
Doddi
Giancarlo
G
Mencarelli
Paolo
P
Pérez-García
Lluïsa
L