Cooperativity in Alcohol-Nitrogen Complexes: Understanding Cryomatrices through Slit Jet Expansions

Area of Science:

• Physical Chemistry
• Spectroscopy
• Chemical Physics

Background:

• Understanding intermolecular interactions in alcohol clusters is crucial for chemical and physical processes.
• Matrix isolation spectroscopy provides insights but can alter intrinsic cluster properties.
• Gas-phase studies offer a complementary approach to probe these interactions.

Purpose of the Study:

• To characterize alcohol dimers with varying numbers of nitrogen molecules using FTIR spectroscopy.
• To investigate the influence of nitrogen coating on OH stretching frequencies.
• To elucidate the relationship between gas-phase spectral shifts and matrix isolation effects.

Main Methods:

• Fourier Transform Infrared (FTIR) spectroscopy was employed.
• Supersonic expansion techniques were used to generate and study alcohol-nitrogen complexes.
• Comparative spectral analysis of different alcohol types (methanol, ethanol, tert-butyl alcohol) and deuterated methanol was performed.

Main Results:

• Nitrogen coating induced progressive downshifts in OH stretching fundamentals, correlating with matrix isolation shifts.
• Alcohol monomers and trimers exhibited greater resistance to nitrogen coating compared to dimers.
• Conformational isomerism and combination bands in ethanol were further clarified.
• The study rationalized the smaller OH stretching dimerization shift in methanol compared to tert-butyl alcohol.

Conclusions:

• Nitrogen coating serves as a valuable tool to mimic and understand matrix isolation effects in gas-phase alcohol clusters.
• The distinct behavior of monomers and trimers highlights the role of cooperativity and hydrogen bonding in cluster stability.
• The findings provide a deeper understanding of alcohol-alcohol and alcohol-nitrogen interactions.