Amphiphilic Styrene-Based Pyrene Derivatives: Tunable Aggregation Luminescence and Their Photo-Induced Dimerization Behavior

Abstract

Since the discovery of the aggregation-induced emission (AIE) phenomenon, various stimuli-responsive materials have been rapidly developed. However, how to achieve the transition between aggregation-caused quenching (ACQ) and AIE through molecular design is an urgent problem to be solved. In this work, we synthesized and studied the aggregation luminescence behavior and photochromism of two different substituted pyrene ethylene derivatives, 1-H and 1-CN. Due to the different substituents attached to the ethylene unit, 1-H exhibits ACQ luminescence behavior. When the substituent is a cyanide group, it exhibits AIE behavior. In addition, the ordered nanoparticles formed by self-assembly in aqueous solution exhibit interesting photo-induced cyclization behavior, which leads to fluorescence quenching under ultraviolet light irradiation (λ = 365 nm). Therefore, due to their amphiphilicity and photo-responsiveness, these compounds can be used as anticounterfeiting inks in information encryption. This work contributes new members to the family of amphiphilic photo-responsive materials and demonstrates their potential applications in optical information storage and multi-color luminescence.

Keywords: aggregation-induced emission; luminescent material; photochemical reaction; pyrene; self-assembly.

Scheme 1

The synthetic route of luminescent compounds 1-H and 1-CN.

Figure 1

(a) Absorbance and (b) fluorescence emission spectra of 1-H and 1-CN in aqueous solution (1 × 10⁻⁵ M).

Figure 2

Normalized emission spectra of (a) 1-H and (b) 1-CN in different organic solvents and water (1 × 10⁻⁵ M).

Figure 3

The emission spectra and the bar chart of the relationship between fluorescence intensity or ratio and the corresponding solvent system of (a,b) 1-H and (c,d) 1-CN in binary solvent mixtures of THF−water and the emission spectra of (e,f) 1-CN in binary solvent mixtures of THF−ethylene glycol. The inset shows a distinct color change in the corresponding mixed solvents (1 × 10⁻⁵ M).

Figure 4

SEM image (a,b) and TEM image (c,d) of 1-H prepared in aqueous solution. SEM image (e,f) and TEM image (g,h) of 1-CN prepared in aqueous solution (1 × 10⁻⁵ M).

Figure 5

(a) The emission spectra of pyrene derivative 1-H in aqueous solution over 30 s with exposure to 365 nm LED light and (b) the time dependence of the fluorescence intensity (I₄₇₂ nm). (c) The emission spectra of pyrene derivative 1-CN in aqueous solution over 60 s with exposure to 365 nm LED light and (d) the time dependence of the ratio of the fluorescence intensity (I₅₃₆ nm/I_{473 nm}). (e) CIE chromaticity diagram showing the time dependence of the (x, y) color co-ordinates of 1-CN.

Figure 6

Photographs of fluorescent inkjet printing-based paper with 1-CN (1 × 10⁻⁵ M) under (a) natural light and (b) ultraviolet light. (c) The color change after being exposed to 365 nm irradiation.

Scheme 2

The schematic diagram of molecular aggregation and photo-cyclization.