Aromatic embedding wins over classical hydrogen bonding - a multi-spectroscopic approach for the diphenyl...

Area of Science:

• Physical Chemistry
• Supramolecular Chemistry
• Spectroscopy

Background:

• Dispersion interactions are crucial but hard to predict in molecular binding.
• Aromatic ethers present competing binding sites: ether oxygen and aromatic π systems.
• Diphenyl ether's dual aromatic rings can favor π-system interactions.

Purpose of the Study:

• Investigate molecular recognition and structure of diphenyl ether-methanol complexes.
• Determine the preferred binding sites and conformations.
• Analyze internal dynamics using multi-spectroscopic techniques.

Main Methods:

• Multi-spectroscopic approach.
• Infrared (IR) spectroscopy.
• Infrared-ultraviolet (IR-UV) double resonance spectroscopy.
• Microwave spectroscopy.

Main Results:

• A preferred conformer features alcohol hydroxyl binding to one phenyl π-cloud and coordinated by the other's C-H bond.
• A second, higher-energy conformer with hydrogen bonding to the ether oxygen was observed.
• Conformer populations depend on supersonic jet expansion conditions.

Conclusions:

• The aromatic π system of diphenyl ether plays a significant role in binding alcohols like methanol.
• Specific conformers are stabilized by distinct non-covalent interactions.
• Spectroscopic methods reveal complex interplay of intermolecular forces and conformational preferences.