Phthalocrowns: Isoindoline–Crown Ether Macrocycles

The reaction of diiminoisoindoline with amine-terminated
polyethers
results in the formation of phthalocrown macrocycles. For n = 1 (where n is the number of ether units),
a 2 + 2 condensation takes place, but for n = 2 and
3, a 1 + 1 macrocycle formation occurs. The n = 2
phthalocrown is particularly stable due to a strong intramolecular
hydrogen bond, but the n = 3 ring hydrolyzes to form
a 3-imino-1-oxoisoindoline derivatized crown ether species. For the n = 1 phthalocrown, we observed dynamic behavior in the 1H NMR spectrum, and using VTNMR were able to measure a ΔG⧧ = 44.6 kJ/mol for proton exchange.