Stacking Interactions between 9-Methyladenine and Heterocycles Commonly Found in Pharmaceuticals

Area of Science:

• Computational Chemistry
• Medicinal Chemistry
• Molecular Interactions

Background:

• Heterocyclic compounds are prevalent in pharmaceuticals.
• Understanding non-covalent interactions is crucial for drug design.
• 9-methyladenine serves as a model nucleobase for stacking studies.

Purpose of the Study:

• To computationally investigate stacking interactions between 9-methyladenine and various drug-like heterocycles.
• To determine the factors influencing the binding enthalpies of these stacked dimers.
• To assess the predictive power of molecular properties like dipole moments.

Main Methods:

• Utilizing dispersion-corrected density functional theory (DFT) to model molecular complexes.
• Generating and analyzing a large dataset of 408 unique stacked dimers.
• Calculating binding enthalpies to quantify interaction strengths.

Main Results:

• Identified a wide range of binding enthalpies, emphasizing orientation dependence.
• Found that NH and carbonyl groups significantly enhance stacking interactions.
• Observed that π-stacking strength is sensitive to heteroatom distribution and tautomerism.
• Noted limited correlation between dipole moments and binding enthalpies for fused heterocycles.

Conclusions:

• Molecular orientation and specific functional groups are key determinants of 9-methyladenine-heterocycle stacking.
• Simple electrostatic models like dipole moments are insufficient for predicting interactions in complex fused systems.
• These findings provide valuable insights for rational drug design and understanding molecular recognition.