Cystine-based cyclic oligoureas: a new class of hydrogen-bonding electroneutral anion receptorsElectronic supplementary information (ESI) available: 1H NMR of 1 (Fig. S1), 2 (Fig. S2); ROESY NMR of 1 (Fig. S3), 2 (Fig. S4); ES-MS of 1 (Fig. S5), 2 (Fig. S6), FAB-MS of 1 (Fig. S7); NMR titration of 2 with squarate TBA salt (Fig. S8); 1H NMR of 1 in CDCl3 (host alone) (Fig. S9), 1 with Cl− in 1∶1 molar ratio (Fig. S10), 1 with Br− in 1∶1 molar ratio (Fig. S11), 1 with NO3− in 1∶1 molar ratio (Fig. S12), 2 in CDCl3 (host alone) (Fig. S13), 2 with squarate dianion in 1∶1 molar ratio (Fig. S14). See http://www.rsc.org/suppdata/cc/b1/b102720b/
Abstract
Cystine-based symmetrical cyclic oligoureas, synthesized in a
one-pot reaction from