Fluorescence resonance energy transfer mediated by vesicles containing naphthalene moiety

A single chain synthetic amphiphile, 4-(2-hexadecyloxynaphthalene-6-oxy)butyl trimethylammonium bromide (C16Naph(2,6)C4N+), can self-assemble into vesicles in the dilute solution. The fluorescence resonance energy transfer has been studied in aqueous vesicle solution of C12Naph(1,5)C4N+ and hydrophilic dye fluorescein sodium salt (FS). The donor, naphthalene group, was embedded in the interior of the vesicles. The acceptor, FS with two negatively charged polar groups, was bound electrostatically to the positively charged surface of (C16Naph(2,6)C4N+) vesicles. The FS quenched the fluorescence intensity of the naphthalene, which fitted a Stern–Volmer plot, and the Stern–Volmer quenching-constant Ksv is 5.65 × 105 mol−1. The energy transfer efficiency increased with the increasing concentration of FS acceptor in the range of 0–4.4 × 10−6 dm3 mol−1 up to ca. 71% which could be ascribed to the ordered arrangement of chromophores inside the vesicles.