A single solvating benzene molecule decouples the mixed-valence complex through intermolecular orbital interactions

Area of Science:

• Supramolecular Chemistry
• Chemical Physics
• Materials Science

Background:

• Characterizing covalency in weak intermolecular interactions at van der Waals distances is difficult due to their dynamic and immeasurable nature.
• Existing theories like dielectric solvation may not fully explain interactions in complex molecular environments.

Purpose of the Study:

• To investigate and characterize the covalency of intermolecular interactions in supramolecular systems.
• To explore the influence of encapsulated molecules on electronic properties of donor-bridge-acceptor systems.
• To demonstrate the potential for controlling chemical properties through site-specific intermolecular interactions.

Main Methods:

• Synthesis and X-ray crystal structure characterization of supramolecular mixed-valence (MV) donor(D)-bridge(B)-acceptor(A) systems with encapsulated C6H6.
• Comparative analysis of intervalence charge transfer (ICT) spectra in different solvents (benzene and dichloromethane).
• Ab initio and Density Functional Theory (DFT) calculations to unravel electronic structures and intermolecular orbital overlaps.

Main Results:

• The encapsulated C6H6 molecule exhibits a strong electronic decoupling effect, challenging the dielectric solvation theory.
• Intermolecular orbital overlaps between the bridge and C6H6 molecule significantly alter the electronic states of the D-B-A system.
• Intermolecular nuclear dynamics play a role in modulating the electronic states.

Conclusions:

• Site-specific intermolecular interactions can be precisely controlled within supramolecular systems.
• This control can be leveraged to tune the chemical properties of these systems.
• The findings provide a framework for understanding and elucidating the functionalities of side-chains in biological systems.