Taming boroloborinines: toward photostable polycyclic antiaromatic hydrocarbons

Area of Science:

• Organic Chemistry
• Materials Science
• Computational Chemistry

Background:

• Boron-containing heterocycles are gaining interest for organic electronics due to their electron-accepting capabilities.
• Boroloborinines, rare 8π-electron antiaromatic systems, show promise but suffer from instability.
• Stabilization strategies are crucial for their practical application in functional organic materials.

Purpose of the Study:

• To investigate methods for stabilizing boroloborinine derivatives.
• To explore the influence of nitrogen incorporation and benzannulation on stability and electronic properties.
• To provide design principles for stable antiaromatic chromophores with tunable optoelectronic characteristics.

Main Methods:

• Density Functional Theory (DFT) and wavefunction-based methods were employed for systematic investigation.
• Photochemical stability was assessed using HOMO-LUMO and singlet-triplet (S-T) energy gaps.
• Aromaticity was evaluated using multicenter index (MCI), HOMA, and magnetically induced current density (MICD).

Main Results:

• Nitrogen incorporation and benzannulation were found to be effective stabilization strategies for boroloborinines.
• Substitution patterns critically affect electronic structure, with Clar's sextets correlating with enhanced stability.
• Molecules with reduced antiaromaticity (singlet) and minimal aromaticity (triplet) exhibited larger S-T gaps, indicating improved photostability.
• Nitrogen proximity to boron increases proton affinity, suggesting susceptibility to acid-catalyzed reactions.

Conclusions:

• Nitrogen incorporation and benzannulation offer viable routes to stabilize boroloborinines.
• Understanding structure-property relationships is key to designing stable antiaromatic chromophores.
• These findings guide the development of novel organic emitters with tailored optoelectronic properties and emission characteristics.