Interplay between σ Holes, Anion···H-C, and Cation-π Interactions in Dibromo[2,2]paracyclophane Complexes

Area of Science:

• Computational chemistry
• Supramolecular chemistry
• Non-covalent interactions

Background:

• Understanding non-covalent interactions is crucial in molecular recognition and self-assembly.
• Paracyclophanes are versatile scaffolds with unique electronic properties.
• The interplay of various non-covalent forces, including σ-hole, cation-π, and anion-HC interactions, dictates complex stability.

Purpose of the Study:

• To investigate the binding characteristics of dibromo[2,2]paracyclophane (DBr[2,2]PCP) with various cations and anions.
• To elucidate the role of σ-hole, cation-π, and anion-HC interactions in DBr[2,2]PCP complexes.
• To assess the influence of halogen substitution on interaction energies.

Main Methods:

• Theoretical calculations using Møller-Plesset perturbation theory (MP2) and density functional theory (M06-2X, B3LYP).
• Utilized the 6-311++G(d,p) basis set for all calculations.
• Analyzed interaction energies and binding preferences.

Main Results:

• DBr[2,2]PCP demonstrates amphoteric behavior with a dominant basic character.
• Strong preference for interactions with hard cations (e.g., Be²⁺) via cation-π and hard anions (e.g., F⁻) via anion-HC interactions.
• Anion-HC interactions are significantly stronger than σ-hole interactions in DBr[2,2]PCP complexes.

Conclusions:

• DBr[2,2]PCP acts as a versatile host for both cations and anions, driven by specific non-covalent interactions.
• The molecule's amphoteric nature and preference for hard species highlight its potential in host-guest chemistry.
• Halogen substitution has a minor impact on the interaction energies of DBr[2,2]PCP-halogen complexes.