Pyrene-containing dyes: Reversible click/declick reaction, optical and aggregation behaviors

Abstract

Pyrene-based dyes were synthesized by a clean, efficient Diels-Alder [4 + 2] click reaction where no catalyst adding or side reactions occurring. The optical behaviors, optoelectronic properties and supramolecular donor/acceptor dipolar interactions of these new dyes were investigated by UV–vis absorption, fluorescence spectroscopy, electrostatic potential and frontier molecular orbital calculations as well as electrochemical cyclic voltammetry measurements. Two pyrene-based dyes can be mutually transformed by reversible formation or cleavage of Diels-Alder covalent bonds through click/declick reaction. During the reversible reaction, switchable fluorescence ON/OFF behaviors were interestingly observed. X-ray single crystal diffraction revealed that supramolecular donor/acceptor dipolar and π-π stacking interactions work cooperatively to form stronger interaction and the shorter distance (3.38 Å) between donor and acceptor than general π-π stacking distance (3.54 Å). An amphiphilic dye is self-assembled in water into blue fluorescent, hollow vesicular aggregates with the average diameter of 115–120 nm and a narrow size distribution as revealed by dynamic light scattering, scanning electron microscopy and transmission electron microscopy.