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

• Identification of glyoxylic acid–water 1:1 complexes for the first time.
• Two hydrogen-bonded complex structures for both two most stable isomers of GA.
• A higher-energy complex structure is found to be most profound in Ar matrix.
• Computational vibrational spectra are in excellent agreement with matrix data.

The 1:1 hydrogen bonded complexes between glyoxylic acid (GA) and water are studied in low temperature argon matrices. Four different complex structures were found in deposited matrices. The lowest energy conformer (T1) of GA was found to form complex, where the water molecule was attached to the opposite side of the intramolecular hydrogen bond in the molecule (T1B). Interestingly, this complex was estimated to be +8.0 kJ mol−1 higher in energy than the most stable structure (T1A), where the water is inserted into the internal hydrogen bond, and also found in solid argon but in smaller abundance. For the second-lowest energy conformer of GA (T2), the two lowest-energy complex structures were identified, with the most stable complex structure (T2A) also being the most abundant in the matrices. The difference between experiment and computational energetic order of the two complex structures of the same GA conformer is explained by contributions of deformation energy upon complexation and the effect of the environment. The computed BSSE-corrected interaction energies are for the two most stable complexes of the two GA conformers for T1A and T2A −42.11 and −45.03 kJ mol−1, respectively, at the CCSD(T)/aug-cc-pVTZ//B3LYP/aug-cc-pVTZ level of theory.

Figure optionsDownload as PowerPoint slide