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Anion-π interactions between the Lewis basic anion fluoride and π-acidic naphthalene diimide was systematically studied in a series of cyclophanes in which the properties are modulated through the influence of a second, electron-rich aromatic unit. The systems and subsequently generated radical anions, upon addition of fluoride, were studied by absorption spectroscopic and EPR techniques. The results infer a modulation as a result of the nature and strength of the π-π interaction in the macrocyclic structure. [ABSTRACT FROM AUTHOR]

Two new amino core-substituted naphthalene diimides (cNDIs) bearing fluorinated side chains have been synthesised. Steady-state and time-resolved fluorescence spectroscopy reveals unprecedented optical properties for the cNDIs with high quantum yields of ~0.8 and fluorescence lifetimes of ~13 ns in a range of solvents. These properties are apparent at the level of single molecules, where the compounds also show exceptional photostability under pulsed-laser excitation. Photon emission is remarkably consistent with very few long timescale (millisecond or longer) interruptions with molecules regularly undergoing >107 cycles of excitation and emission. Intermittencies owing to triplet-state formation occur on a sub-millisecond timescale with a low yield of 1-2%, indicating that the presence of the fluorine atoms does not lead to a significant triplet yield through the heavy-atom effect. These properties make the compounds excellent candidates for single-molecule labelling applications. [ABSTRACT FROM AUTHOR]

Symmetrically and dissymmetrically core-substituted amino naphthalene diimides (cNDIs) with water-soluble substituents have been synthesised. The compounds display characteristic steady-state optical properties absorbing and emitting light in the visible part of the electromagnetic spectrum. Time-resolved fluorescence studies reveal long emission lifetimes of ∼10 ns in chloroform, ∼8 ns in methanol and ∼4 ns in water. Suitability for use in biophysical applications is demonstrated by encapsulation into reverse micelles and liposomes. Fluorescence lifetime is shown to indicate cavity size in the reverse micelles and fluorescence correlation spectroscopy measurements of cNDI loaded liposomes successfully determined diffusion coefficients and hydrodynamic radii of the liposomes. [ABSTRACT FROM AUTHOR]