Matrix isolation and low temperature solid state FTIR spectroscopic study of alpha-furil.

Area of Science:

• Physical Chemistry
• Spectroscopy
• Computational Chemistry

Background:

• Understanding molecular conformation is crucial for predicting chemical and physical properties.
• Alpha-furil's conformational landscape has not been fully elucidated across different states.

Purpose of the Study:

• To investigate the conformational behavior of alpha-furil in matrix isolation and condensed phases.
• To assign FTIR spectra using theoretical calculations and identify different conformers.
• To determine energy barriers for conformational interconversion.

Main Methods:

• Isolation of alpha-furil in argon and xenon matrices.
• Fourier-transform infrared (FTIR) spectroscopy.
• Density Functional Theory (DFT) calculations (B3LYP/6-311++G(d,p)).

Main Results:

• Three distinct conformers of alpha-furil were identified in argon and xenon matrices, all exhibiting skewed conformations around the intercarbonyl bond.
• Conformer I (C(2) symmetry) is the most stable, with both furan rings oriented to form six-membered rings via beta-hydrogen interactions.
• Conformers II and III, with different furan ring orientations, are higher in energy, and energy barriers for interconversion exceed 40 kJ mol(-1), preventing isomerization in matrices.

Conclusions:

• Alpha-furil exists as three conformers in matrices, CCl(4) solution, and amorphous solid phases.
• In the crystalline state, only the most stable conformer (I) is observed, consistent with X-ray data.
• The high energy barriers effectively isolate the observed conformers in low-temperature phases.