A quantitative measure of halogen bond activation in cocrystallization

Area of Science:

• Supramolecular Chemistry
• Computational Chemistry
• Crystal Engineering

Background:

• Halogen bonding is a key non-covalent interaction in crystal engineering.
• Understanding and predicting halogen bond strength is crucial for designing functional materials.
• Activating groups significantly influence halogen bond characteristics.

Purpose of the Study:

• To theoretically investigate halogen bond lengths and energies.
• To quantify the effect of various activating agents on halogen bond strength.
• To provide guidelines for crystal engineers based on computational predictions.

Main Methods:

• Utilized the PIXEL computational method for theoretical investigation.
• Assessed the impact of fluoro-, nitro-, and ethynyl substitutions on halogen bonds.
• Correlated binding energies with electrostatic potential and atomic charges.

Main Results:

• Halogen bond strength is significantly enhanced by activating agents.
• The strongest halogen bonds were comparable or superior to strong hydrogen bonds.
• Halogen bonding was identified as a primary force in cocrystal packing.

Conclusions:

• The PIXEL method accurately predicts halogen bond strengths.
• Activating groups offer a tunable approach to designing strong halogen bonds.
• Computational parameters like electrostatic potential can guide crystal engineering efforts.