7,7′-disubstituted BINOLs as multifunctional fluorescent materials: Solid-state emission, visualization of latent fingerprints and acidochromic properties

Abstract

Organic fluorescent materials have attracted more and more attention for their applications in various fields. In this work, binaphthanol-based fluorescent molecules with 7 and 7′ substitutions have been designed and synthesized. These molecules show blue fluorescence in organic solutions with good quantum yields and bright emission in the solid state. The compound with pyridin-4-yl vinyl groups exhibits solvatochromic properties and has large Stokes shifts in methanol and DMSO solution. This compound can be used for the visualization of latent fingerprints on various substrates with smooth or rough surfaces, and high contrast fingerprint images have been obtained. These results indicate that this compound has potential utility for personal identification. Further investigation reveals that compounds with pyridine groups have acidochromic properties. With the addition of trifluoroacetic acid, the fluorescence intensity of these molecules in solution decreased and the emission wavelengths were redshifted significantly. The emission intensity and color of these molecules can be adjusted by fumigation with trifluoroacetic acid and triethylamine vapor. These results suggest that these compounds can be used as anti-counterfeit fluorescent materials. This work provides a new strategy for the preparation of binaphthanol-based fluorescent materials with multiple functions.