Fig. 6. (a) Time-dependent changes in the (a) ratio of the emission intensities of 8-hydroxypyrene-1,3,6-trisulfonate (HPTS, 0.1 mM) encapsulated inside large unilamellar vesicles (LUVs) of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). Solutions of LUVs (KCl 145 mM, HEPES 100 mM, pH 7.0) were first mixed with 3a, 3c, gramicidin (added from 1 mM stock solutions in THF), or THF (control) and then incubated for 2 min, followed by a HCl (2 M) pulse. The ratio of emission intensities at 510 nm by exciting at 450 nm and 405 nm respectively was monitored over 5 min; (b) the fluorescence intensity of N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide (MQAE) encapsulated inside LUVs of POPC. Solutions of Cl^– free LUVs (10 mM MQAE, potassium gluconate 100 mM, HEPES 100 mM, pH 7.4) were first incubated with KCl (100 mM) in HEPES (100 mM, pH 7.4) buffer for 1 min. Stock solutions of 3a, 3c, gramicidin (1 mM in THF) and THF (control) were added to monitor the change of emission intensity at 460 nm (λ _ex = 354 nm) for 5 min. The LUVs were ruptured by adding 200 μ(L of 1×X lysis buffer (1.55 mM Triton X-100 in pH 7.0 Tris-EDTA) (for (a)) or 200 μ(L of Triton X-100 (3.1 mM in H₂O) (for (b)).