Wavelength resolved specific optical rotations and homochiral equilibria

Area of Science:

• Chiroptical spectroscopy
• Photochemistry
• Physical chemistry

Background:

• Monomer-dimer equilibria are crucial in understanding homochiral systems.
• Specific optical rotations (SORs) provide insights into molecular chirality.
• Wavelength-resolved circular birefringence (WRCb) is a sensitive technique for studying chiral molecules.

Purpose of the Study:

• To present fundamental expressions for SORs in homochiral systems with monomer-dimer equilibria.
• To experimentally determine the wavelength-resolved SORs of monomer and dimer components for (R)-(-)-α-hydroxy-β,β-dimethyl-γ-butyrolactone.
• To validate theoretical predictions of chiroptical properties using experimental data.

Main Methods:

• Derivation of theoretical equations for specific optical rotations in systems with monomer-dimer equilibria.
• Experimental measurement of wavelength-resolved circular birefringence for (R)-(-)-α-hydroxy-β,β-dimethyl-γ-butyrolactone.
• Comparison of experimental results with density functional theory (DFT) predictions.

Main Results:

• The study successfully derived governing expressions for SORs in homochiral monomer-dimer systems.
• Wavelength-resolved SORs for both monomer and dimer of (R)-(-)-α-hydroxy-β,β-dimethyl-γ-butyrolactone were determined experimentally for the first time.
• DFT predictions for monomer and dimer dispersion properties showed agreement with experimental data within a factor of approximately 2.

Conclusions:

• Wavelength-resolved circular birefringence is a powerful tool for investigating molecular properties in homochiral equilibria.
• The study provides a quantitative method for characterizing chiral species in equilibrium.
• Accurate theoretical modeling can complement experimental studies of chiroptical properties.