Direct enantiomeric discrimination through antisymmetric hyperfine coupling.

Area of Science:

• * Molecular spectroscopy
• * Quantum chemistry
• * Chirality studies

Background:

• * Chiral molecules are crucial in pharmaceuticals and materials science.
• * Distinguishing between enantiomers (non-superimposable mirror images) is experimentally challenging.
• * Electron Paramagnetic Resonance (EPR) spectroscopy probes unpaired electrons in open-shell molecules.

Purpose of the Study:

• * To explore a novel EPR-based method for direct enantiomeric discrimination.
• * To investigate the role of electric dipole moments and hyperfine coupling in chiral EPR signals.
• * To identify suitable molecular candidates for experimental validation.

Main Methods:

• * Theoretical calculations using quantum chemistry.
• * Analysis of EPR signal phase dependence on molecular properties.
• * Investigating the vector antisymmetry of hyperfine coupling interactions.

Main Results:

• * Chiral open-shell molecules with permanent electric dipole moments exhibit EPR signals at the difference frequency of electron and nuclear resonances.
• * The phase of the EPR signal directly correlates with the molecule's enantiomer.
• * Quantum chemistry predicts chiral bisfluorene methyl radical derivatives as promising candidates for this technique.

Conclusions:

• * A new EPR-based approach allows direct enantiomeric discrimination through signal phase.
• * This method is applicable to chiral open-shell molecules with electric dipole moments.
• * Chiral bisfluorene methyl radicals are proposed for experimental demonstration of this enantioselective EPR technique.