Aggregation-Induced Emission Materials with Narrowed Emission Band by Light-Harvesting Strategy: Fluorescence and Chemiluminescence Imaging

Aggregation-induced emission luminogens (AlEgens) have attracted increasing attention in recent years on account of their attribute of overcoming the aggregation-caused quenching (ACQ) phenomenon of conventional organic fluorophores. Despite their remarkable advantages and great developments, most organic AlEgens exhibit broad emission spectra with the full width at half-maxima (FWHM) over 100 nm, which is to the disadvantage of their practical applications. Herein, supramolecular polymeric AIE materials with brighter fluorescence and narrower emission band (higher color purity) than conventional AlEgens were developed by taking advantage of the light-harvesting strategy. These AIE materials, including nanoparticles, microfibers, and thin films, were fabricated from supramolecular polymers comprising quadruple hydrogen-bonded monomer tetraphenylethylene (TPE) and borondipyrromethene (BODIPY) as antenna chromophores and as energy acceptors, respectively. The excitation energy collected by TPE molecules was efficiently transferred to the BODIPY, resulting in up to 6 fold enhanced fluorescence intensity and narrowed emission band with FWHM decreasing from 148 to 32 nm. The resulting nanoparticles showed similar to 5-fold higher brightness than commercial quantum dots. The highly fluorescent nanoparticles were successfully applied for in vitro and in vivo fluorescence and chemiluminescence imaging, showing superior imaging performance to conventional AIE nanoparticles.