Enhanced Emission and Its Switching in Fluorescent Organic Nanoparticles

TLDR

The study introduces CN‑MBE nanoparticles, a new class of ~30–40 nm organic particles designed to exhibit strongly enhanced fluorescence. The nanoparticles were produced by simple reprecipitation, and their enhanced fluorescence arises from intramolecular planarization coupled with J‑type aggregation that limits excimer formation. CN‑MBE nanoparticles show almost 700‑fold brighter fluorescence than the monomer and enable on/off switching in response to organic vapors.

Abstract

A new class of organic nanoparticles (CN-MBE nanoparticles) with a mean diameter of ca. 30−40 nm, which exhibit a strongly enhanced fluorescence emission, were prepared by a simple reprecipitation method. CN-MBE (1-cyano-trans-1,2-bis-(4'-methylbiphenyl)ethylene) is very weakly fluorescent in solution, but the intensity is increased by almost 700 times in the nanoparticles. Enhanced emission in CN-MBE nanoparticles is attributed to the synergetic effect of intramolecular planarization and J-type aggregate formation (restricted excimer formation) in nanopaticles. On/off fluorescence switching for organic vapor was demonstrated with CN-MBE nanoparticles.