Solvent Effects on the Selectivity of Ambimodal Dipolar/Diels-Alder Cycloadditions: A Study Using Explicit Solvation...

Area of Science:

• Chemical Dynamics
• Computational Chemistry
• Reaction Mechanisms

Background:

• Post-transition state bifurcation (PTSB) describes reactions proceeding through a single transition state to multiple products.
• Previous studies indicated polar solvents significantly influence PTSB by stabilizing charge-separated intermediates.
• Implicit solvation models have limitations in capturing detailed solvent-solute interactions.

Purpose of the Study:

• To investigate the influence of explicit solvation on PTSB dynamics.
• To explore the role of water molecule clusters in controlling reaction branching.
• To compare explicit solvation results with previous implicit solvation findings.

Main Methods:

• Utilized an explicit solvation model with up to 45 water molecules.
• Performed static reaction path calculations and molecular dynamics simulations.
• Employed the semiempirical GFN2-xTB method, validated against density functional theory (DFT).

Main Results:

• PTSB dynamics demonstrated high sensitivity to the number of explicit water molecules.
• Explicit solvation effects on reaction pathways were quantified.
• GFN2-xTB method accurately reproduced DFT results for the studied system.

Conclusions:

• The number of explicit solvent molecules is a critical factor in controlling PTSB.
• Explicit solvation models provide a more detailed understanding of solvent effects on reaction dynamics.
• This research highlights the importance of explicit solvent representation in computational chemical studies.