Modular Donor-Acceptor Diradicaloids Based on an Electron Deficient N-Heteroacene Acceptor

Area of Science:

• Organic electronics
• Materials science
• Quantum chemistry

Background:

• Conjugated organic molecules with open-shell diradical character are crucial for understanding electron pairing and spin manipulation.
• Existing materials often lack modularity, tunable diradical character, stability, and diverse functionalities.

Purpose of the Study:

• To develop novel donor-acceptor-donor diradicaloids with enhanced properties.
• To establish structure-property relationships for tuning electronic and spin characteristics.

Main Methods:

• Facile synthesis of diradicaloids using a tetrachlorothiadiazolophenazine core and thiophene donors.
• Characterization using Nuclear Magnetic Resonance (NMR) and Electron Paramagnetic Resonance (EPR) spectroscopies.
• Theoretical investigations using long-range corrected Mixed-Reference Spin-Flip Time-Dependent Density Functional Theory (TD-DFT).

Main Results:

• Demonstrated facile synthesis of modular donor-acceptor-donor diradicaloids.
• Correlated narrowing of singlet-triplet splitting (ΔE_ST) and π-conjugation extension with increased diradical character.
• Showcased tunable structural, electronic, spin, magnetic, and transport properties.
• Validated TD-DFT for predicting multireference electronic structure.

Conclusions:

• The developed diradicaloids offer high modularity and tunable diradical character.
• Insights enable the design of new open-shell materials with controlled optoelectronic and transport functionalities.
• Facilitates manipulation of electronic structure, topology, and exchange interactions for advanced applications.