Alternative Kullback-Leibler information entropy for enantiomers

Area of Science:

• * Computational Chemistry
• * Molecular Modeling
• * Physical Chemistry

Background:

• * Quantifying molecular chirality is crucial in chemistry and drug development.
• * Previous methods for chirality quantification lacked direct experimental correlation.
• * Chirality measures often used one enantiomer as a reference for the other.

Purpose of the Study:

• * To introduce a new, mathematically elegant chirality measure.
• * To develop an index directly relatable to experimental techniques.
• * To analyze chiral halomethanes using the novel measure.

Main Methods:

• * Application of Kullback-Leibler information entropy to define a new chirality index.
• * Calculation of the index for five chiral halomethanes (CHFIBrCl, CHFIBrH, etc.).
• * Comparison with calculated optical rotation and Avnir's Continuous Chirality Measure (CCM).

Main Results:

• * The new index is symmetric, positive definite, and zero for nonchiral systems.
• * The index shows a stronger correlation with experimental measurements (CD, optical rotation).
• * Analysis highlights differences between non-coinciding substituents in chiral molecules.

Conclusions:

• * The proposed Kullback-Leibler based index is a robust measure of molecular chirality.
• * This method provides a more direct link to experimental chirality assessments.
• * The index effectively emphasizes substituent differences in chiral systems.