Isolated glyoxylic acid-water 1:1 complexes in low temperature argon matrices

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Spectroscopy

Background:

• Glyoxylic acid (GA) is a key organic compound with implications in biochemistry and atmospheric chemistry.
• Understanding the interactions of GA with water is crucial for various chemical processes.
• Low-temperature matrix isolation provides a unique environment to study weakly bound molecular complexes.

Purpose of the Study:

• To investigate the structures and energetics of 1:1 hydrogen bonded complexes between glyoxylic acid and water.
• To identify different conformers of glyoxylic acid and their corresponding water complexes.
• To compare experimental findings with computational predictions for complex stability.

Main Methods:

• Matrix isolation spectroscopy in low-temperature argon.
• Computational chemistry methods, including DFT (B3LYP/aug-cc-pVTZ) and coupled-cluster theory (CCSD(T)/aug-cc-pVTZ).
• Analysis of vibrational frequencies and interaction energies, including BSSE correction.

Main Results:

• Four distinct 1:1 glyoxylic acid-water complex structures were identified in argon matrices.
• The most stable complex (T1A) involves water insertion into the intramolecular hydrogen bond of the lowest energy GA conformer (T1).
• Another stable complex (T2A) was observed for the second-lowest energy GA conformer (T2), and was the most abundant.

Conclusions:

• The study elucidates the preferred binding sites of water to different glyoxylic acid conformers.
• Discrepancies between experimental and computational energy ordering are attributed to deformation energy and environmental effects.
• Calculated interaction energies for the most stable complexes range from -42.11 to -45.03 kJ mol(-1).