Dynamics and Conformational Stability of Chiral Bay-Phenolate-Substituted Twisted Octaazaperopyrenedioxides (OAPPDOs)

Area of Science:

• Organic Chemistry
• Materials Science
• Photophysics

Background:

• Chiral fluorophores are crucial for advanced optical applications.
• Octaazaperopyrene dioxide (OAPPDO) derivatives offer a promising scaffold for novel materials.
• Developing stable chiral molecules with tunable photophysical properties remains a challenge.

Purpose of the Study:

• To synthesize configurationally stable chiral OAPPDO derivatives.
• To investigate the chiroptical properties, including circular dichroism and circular polarized luminescence (CPL).
• To study the conformational equilibria and racemization stability of these novel fluorophores.

Main Methods:

• Nucleophilic substitution reactions to introduce chiral BINOL fragments.
• Spectroscopic techniques (NMR) for in situ observation of conformers.
• Density Functional Theory (DFT) modeling for conformational analysis and stability assessment.

Main Results:

• Successful synthesis of novel, bright, thermally stable chiral OAPPDO fluorophores.
• Observation of chiral conformer equilibria in solution, with two species identified by NMR.
• Low circular polarized luminescence (CPL) dissymmetry factor (g_lum) around 2*10^-4.
• DFT calculations predicted a high activation barrier (>170 kJ mol^-1) against racemization.

Conclusions:

• Chiral BINOL bridging units impart configurational stability to OAPPDO derivatives.
• These derivatives represent a new class of chiral fluorophores with potential applications in chiroptical devices.
• Further optimization is needed to enhance the CPL dissymmetry factor for practical applications.