Interaction Between the Rubidium Cation and [2.2.2]Paracyclophane: Experimental and Theoretical Study.

Area of Science:

• Supramolecular Chemistry
• Physical Chemistry
• Computational Chemistry

Background:

• Paracyclophanes are macrocyclic compounds known for their ability to host guest molecules.
• Cation-π interactions are crucial in various chemical and biological processes.
• Understanding host-guest chemistry with alkali metal cations is essential for developing new materials and separation techniques.

Purpose of the Study:

• To investigate the reaction between rubidium cations (Rb+) and [2.2.2]paracyclophane.
• To determine the structure and stability of the resulting complex.
• To explore the potential of [2.2.2]paracyclophane as a receptor for Rb+ in the gas phase.

Main Methods:

• Electrospray ionization mass spectrometry (ESI-MS) was used to experimentally detect the complex.
• Quantum chemical calculations were employed to determine the most probable conformation.
• Binding energy was calculated to quantify the complex's stability.

Main Results:

• The formation of the cationic complex [Rb(C24H24)]+ was experimentally confirmed.
• Quantum chemical calculations revealed a stable complex with C3 symmetry, where Rb+ is located within the paracyclophane cavity.
• The rubidium cation interacts with all three benzene rings of the ligand via cation-π interactions.
• The binding energy was calculated to be -99.3 kJ/mol, indicating a stable complex.

Conclusions:

• The [2.2.2]paracyclophane ligand effectively binds rubidium cations in the gas phase.
• The observed cation-π interactions are key to the stability of the [Rb(C24H24)]+ complex.
• [2.2.2]paracyclophane can be considered a rubidium cation receptor.