Design of an open-shell nitrogen-centered diradicaloid with tunable stimuli-responsive electronic properties

Area of Science:

• Organic Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Organic diradicaloids exhibit open-shell singlet ground states with significant diradical character, leading to unique properties and applications.
• Tuning diradical character and electronic properties is crucial for developing advanced functional materials.

Purpose of the Study:

• To design and synthesize a novel nitrogen-centered diradicaloid with tunable diradical character and stimuli-responsive properties.
• To investigate the reversible response of the diradicaloid to external stimuli, such as Lewis acids and light.
• To explore the potential of this diradicaloid in developing intelligent-responsive materials.

Main Methods:

• A two-step synthetic strategy was employed for the high-yielding synthesis of the target compound (1a).
• Experimental techniques and computational calculations were used to characterize the electronic structure, diradical character (y0), and singlet-triplet energy gap (ΔE_S-T).
• Reversible Lewis acid-base reactions and photoresponsive behavior with merocyanine (MEH) were investigated.

Main Results:

• The synthesized compound 1a exhibits an open-shell singlet ground state with a modest diradical character (y0 = 0.60) and a small singlet-triplet energy gap (ΔE_S-T = -2.311 kcal mol^-1).
• 1a undergoes reversible Lewis acid-base reactions, allowing for effective tuning of its diradical character, spin density distribution, and ground-state electronic structure.
• A photoresponsive system was successfully developed using 1a and a photoacid merocyanine (MEH).

Conclusions:

• The developed molecular design methodology provides a new approach for creating organic diradicaloids with tunable properties.
• The synthesized nitrogen-centered diradicaloid demonstrates significant potential for applications in stimuli-responsive materials.
• This work opens avenues for the development of intelligent diradicaloid-based materials with tailored functionalities.