Dynamics of exchange in linear and cyclic supramolecular aggregates based on quadruple hydrogen bonding

摘要: Due to the high dimerization const. of ureidopyrimidinone (UPy), mols. contg. two such units form large polymeric aggregates, which are in equil. with cyclic species. We have investigated dynamics exchange solns. bifunctional compds. 1 and 2, using EXSY 2D-NMR size exclusion chromatog. (SEC). Exchange spectroscopy on mixed linear aggregates 1a 1b shows that kinetics between assocd. UPy is different from monofunctional compds., takes place via a long-lived intermediate. Simulation size-exclusion chromatograms 2 show dimers fast timescale, although it slow NMR timescale. [on SciFinder (R)]