Optically Controlled Thermochromic Switching for Multi-Input Molecular Logic.

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Chemical Engineering

Background:

• Thermochromic materials based on leuco dyes exhibit reversible color changes, enabling molecular logic applications.
• Current limitations include uncontrollable stable color states due to spontaneous protonation.
• Developing methods for temperature-controlled bistable color function remains a challenge.

Purpose of the Study:

• To design an effective approach for controlling bistable color states in leuco dye-based systems.
• To introduce azobenzene derivatives as protonation competitors for enhanced control.
• To demonstrate optically controlled molecular logic operations.

Main Methods:

• Synthesized a family of azobenzene derivatives (AZO(n)) with varying alkyl chains.
• Investigated hydrogen bonding and Van der Waals forces between color developers and AZO(n).
• Utilized Z-to-E photoisomerization of azobenzenes to control protonation states.

Main Results:

• Azobenzene derivatives (AZO(n)) were designed to compete for protonation with leuco dyes.
• The Z-AZO(n) isomer locked the color developer, maintaining the protonated state for over 16 hours.
• Z-to-E photoisomerization released the proton, enabling reversible color control.
• Demonstrated a visible sequential logic operation with four-input signals.

Conclusions:

• Developed a novel optically controlled system for leuco dye-based thermochromic materials.
• Achieved controllable bistable color states using azobenzene-mediated protonation competition.
• This work presents a new paradigm for protonation-based optical control in molecular logic systems.