Illuminating the Performance of Electron Withdrawing Groups in Halogen Bonding

Area of Science:

• Computational chemistry
• Supramolecular chemistry
• Chemical bonding

Background:

• Halogen bonding is crucial in molecular interactions.
• Electron withdrawing groups (EWGs) are commonly used to tune halogen bond strength.
• The specific electronic interplay of EWGs is often overlooked.

Purpose of the Study:

• To investigate the sigma- and pi-electron donating/accepting character of EWGs.
• To understand how these electronic effects influence halogen bond donors.
• To correlate substituent effects with halogen bond complex binding strength.

Main Methods:

• Computational modeling of halo-alkyne, halo-benzene, and halo-ethynyl benzene donors.
• Analysis of sigma-hole magnitude and binding energies with an ammonia acceptor.
• Statistical analysis of substituent electronic effects.

Main Results:

• Substituent electronic properties significantly impact sigma-hole magnitude.
• Both sigma- and pi-electron accepting EWGs enhance halogen bond strength.
• Strongest halogen bond complexes were formed with EWGs exhibiting dual sigma- and pi-electron accepting capabilities.

Conclusions:

• The electronic nature of substituents is a key determinant of halogen bond strength.
• Understanding the interplay of sigma- and pi-effects in EWGs is vital for designing strong halogen bond donors.
• This study provides insights into rational design of halogen bonding interactions.