Enhancing the utility of ¹J_CH coupling constants in structural studies through optimized DFT analysis

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Organic Chemistry

Background:

• Traditional DFT methods for 1JCH coupling constants often require empirical corrections.
• Achieving accurate predictions necessitates adjustments like ad hoc factors, functional modifications, or empirical scaling.

Purpose of the Study:

• To develop and validate a Density Functional Theory (DFT) approach for accurate 1JCH coupling constant prediction without empirical adjustments.
• To demonstrate the utility of this method in conformational and stereochemical analysis of complex organic molecules.

Main Methods:

• Careful selection of DFT methods for geometry optimization and J-coupling calculations.
• Utilized B3LYP/6-31G(d,p)(mixed)//mPW1PW/cc-pVTZ as a representative accurate method.
• Cross-validation against a diverse dataset of 122 1JCH couplings.

Main Results:

• Highly accurate 1JCH coupling predictions were achieved without ad hoc correction factors, functional modifications, or empirical scaling.
• The proposed DFT method demonstrated excellent performance across a wide range of 1JCH couplings.
• Successful application to the conformational and stereochemical analysis of strychnine and a novel diterpene.

Conclusions:

• A robust DFT methodology enables accurate 1JCH coupling constant calculations, eliminating the need for empirical adjustments.
• This validated approach provides a reliable tool for structural elucidation in organic and natural product chemistry.
• The method's success in analyzing complex molecules highlights its practical applicability.