The Solid-State Multi-Color Fluorescence Switching from a [2.2]Paracyclophane-Based Triarylborane

Area of Science:

• Materials Science
• Organic Chemistry
• Photophysics

Background:

• Developing solid-state fluorophores with switchable multicolor emission is challenging.
• Such materials are crucial for advanced displays, encryption, and anti-counterfeiting systems.

Purpose of the Study:

• To synthesize and characterize a novel fluorophore, g-BPhANMe2-Cp, with switchable multicolor luminescence.
• To investigate its mechanochromic and acidochromic luminescence properties for potential applications.

Main Methods:

• Synthesis of g-BPhANMe2-Cp featuring electron-donating and -accepting groups on a paracyclophane scaffold.
• Investigation of mechanochromic luminescence (MCL) through mechanical grinding, heating, and solvent fuming.
• Evaluation of acidochromic luminescence (ACL) via protonation/deprotonation using trifluoroacetic acid and triethylamine.

Main Results:

• g-BPhANMe2-Cp exhibits high fluorescence efficiency (ΦF=0.60-0.87) in the solid state due to suppressed π-π interactions.
• Tricolor MCL was observed, with emission color changing based on mechanical treatment and subsequent stimuli.
• Reversible ACL was demonstrated, with protonation shifting emission to shorter wavelengths (ΦF=0.31).

Conclusions:

• g-BPhANMe2-Cp offers tunable solid-state emission across four colors (yellow, green, cyan, blue) by combining MCL and ACL.
• This molecule presents a promising platform for advanced multicolor displays and security applications.