Solvent complexes of jet-cooled β-phenylethylamine

Area of Science:

• Physical Chemistry
• Molecular Spectroscopy
• Supramolecular Chemistry

Background:

• Beta-phenylethylamine (BPEA) is a crucial neurotransmitter and a building block for many biomolecules.
• Understanding the conformational landscape of BPEA and its interactions with solvents is vital for molecular recognition and drug design.

Purpose of the Study:

• To investigate the conformers of bare beta-phenylethylamine molecules using laser-induced fluorescence spectroscopy.
• To explore the influence of solvent molecules (water and alcohol) on the conformational preferences of BPEA.
• To elucidate the role of the para-hydroxyl group in solvent-induced conformational changes by comparing BPEA with tyramine.

Main Methods:

• Supersonic gas expansions were employed to cool BPEA molecules to investigate their bare spectra.
• Laser-induced fluorescence (LIF) spectroscopy was utilized to probe the electronic transitions and identify different conformers.
• Comparative spectral analysis was performed with and without solvent molecules (water, alcohol) and in relation to tyramine spectra.

Main Results:

• Four distinct conformers of bare BPEA were identified through their unique 0-0 transitions in the LIF spectra.
• The addition of water or alcohol solvents induced new spectral features, distinct from the bare molecule transitions.
• The observed spectral patterns upon solvent addition to BPEA differed significantly from those of tyramine, which possesses a para-hydroxyl group.

Conclusions:

• The study successfully identified multiple conformers of beta-phenylethylamine in the gas phase.
• Solvent interactions with BPEA lead to distinct conformational changes that are spectroscopically observable.
• The presence of a para-hydroxyl group, as in tyramine, plays a significant role in modulating solvent-induced conformations of related molecules.