Hydrogen-bonded complexes of glycolic acid with one and two water molecules

Thakkar, Ajit J.; Kassimi, N. El-Bakali; Hu, Shaowen

doi:10.1016/j.cplett.2004.02.012

Cited by 20 publications

(12 citation statements)

References 27 publications

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“…differ by less than 0.9 kcal/ mol from the more accurate values, 10.17 and 16.38 kcal/ mol for n = 1 and n = 2, respectively, obtained previously by MP2 calculations in large basis sets 21. …”

contrasting

confidence: 65%

“…22 The PM3 relative energies of the local minima are not particularly reliable 19,21,23 and hence we follow up with two single-point energies for each PM3 minimum. 22 The PM3 relative energies of the local minima are not particularly reliable 19,21,23 and hence we follow up with two single-point energies for each PM3 minimum.…”

Section: Methodsmentioning

confidence: 99%

“…21 Finally, singlepoint energies for the resulting structures are computed at the B3LYP/pc2 and B3LYP/pc3 levels. This level of calculation produced structures of the same quality as MP2 computations in significantly larger basis sets for the gw and gw 2 complexes.…”

Section: Methodsmentioning

confidence: 99%

“…21 All but two of the reported structures had the glycolic acid in G, T, or V conformations. The only theoretical or experimental studies of such clusters that we are aware of are ab initio calculations that were used to locate 12 and 17 local minima on the potential energy surfaces of the gw ͑CH 2 OHCOOH -H 2 O͒ and gw 2 ͑CH 2 OHCOOH -H 2 O-H 2 O͒ complexes, respectively.…”

Section: Introductionmentioning

confidence: 95%

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Clusters of glycolic acid with three to six water molecules

Roy

Hu²,

Thakkar³

2005

The Journal of Chemical Physics

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Semiempirical, ab initio, and density functional theory calculations are used to locate many low-energy minima on the potential energy surfaces of the CH2OHCOOH-(H2O)n complexes with n = 3,4,5,6. In the clusters with three, four, and five water molecules, the lowest-energy structure consists of a (H2O)n complex, not necessarily of lowest energy, hydrogen bonded to the carboxylic group of the glycolic acid. The lowest-energy structure for n = 6 is similar except that the water hexamer is hydrogen bonded to both the carboxylic and alpha-hydroxyl groups of the acid. In all the lowest-energy clusters, the intramolecular hydrogen bond remains intact in the glycolic acid.

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contrasting

confidence: 65%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

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Clusters of glycolic acid with three to six water molecules

Roy

Hu²,

Thakkar³

2005

The Journal of Chemical Physics

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“…Vibrational spectra of this molecule have been studied using experimental and theoretical methods, yet these studies have been limited by spectral overlap of the two O−H stretches. , Specifically, the ν 1 and ν 2 normal modes (where ν 1 is the acid O−H stretching mode and ν 2 is the alcohol O−H stretching mode) coincidentally occur at the same frequency in both the fundamental and first overtone regions. The nature of the two O−H stretching transitions is interesting because the alcohol O−H stretch exhibits intramolecular hydrogen bonding 2 while the O−H stretch of the acid is available for intermolecular hydrogen bonding. , Thus, CH 2 OHCOOH is an intriguing prototype system for understanding perturbations to vibrational spectra of organic acids from intra- and intermolecular interactions.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Theoretical Investigation of Vibrational Overtones of Glycolic Acid and Its Hydrogen Bonding Interactions with Water

et al. 2006

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The present work reports observations of the 4nu(1) and 4nu(2) O-H stretching transitions in glycolic acid, CH(2)OHCOOH, using a highly sensitive cavity ring-down spectrometer. Experimental and theoretical values for the harmonic frequencies and anharmonic constants of both O-H stretching transitions were extracted and are compared with theoretical calculations in the literature. Calculations of anharmonic frequencies, intensities, and relative energies have been performed and are presented for three conformers of glycolic acid. In the presence of water, an interesting broad spectral feature appeared underneath 4nu(1) and 4nu(2). New calculations for harmonic frequencies, intensities, and relative energies of four CH(2)OHCOOH-H(2)O complexes are reported to aid in understanding the observed spectrum. This work suggests that the perturbations are caused by intermolecular hydrogen bonding of glycolic acid with one or more water molecules.

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A computational study of the carboxylic acid of phloroglucinol in vacuo and in water solution

Mammino

Kabanda

2009

Int J of Quantum Chemistry

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2,4,6-Trihydroxybenzoic acid (FA) is the carboxylic acid of phloroglucinol and, in turn, the parent compound of many biologically active compounds. The biological activities of FA are "extreme" among trihydroxybenzoic acids (e.g., lowest antioxidant activity, highest toxicity toward crustaceans). A complete MP2/6-31ϩϩG(d,p) conformational study in vacuo shows that the lowest energy conformers contain two intramolecular hydrogen bonds between the COOH function and the two ortho phenolic OH, with the Z form of COOH preferred over the E form. Comparisons with conformers in which the H-bonds are removed enable fairly reliable evaluations of their energy, because of an off-plane shift of COOH on H-bond removal, decreasing the effects of lone pair repulsion. Comparisons with the other hydroxybenzoic acids (extensively calculated in vacuo at the same level of theory) suggest that FA has the strongest intramolecular H-bonds. PCM calculations of FA in water solution show the same sequence of relative stabilities as in vacuo, with narrower differences because of the greater solvent stabilization of higher energy conformers. Calculations of adducts with water molecules H-bonded to different donor-acceptor centers of FA show the preferred arrangements of water molecules around the different regions of FA and confirm that the stronger intramolecular H-bonds are not broken on competition with the possibility of formation of intermolecular H-bonds. HF/6-31ϩϩG(d,p) calculations of adducts, in which the FA molecule is completely surrounded by water molecules, show that 14 -16 water molecules (depending on the FA conformer geometry) realize arrangements corresponding to a presumable first solvation layer, with all the water molecules directly H-bonded to donor-acceptor centers of FA or bridging water molecules directly H-bonded to them.

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Hydrogen-bonded complexes of glycolic acid with one and two water molecules

Cited by 20 publications

References 27 publications

Clusters of glycolic acid with three to six water molecules

Clusters of glycolic acid with three to six water molecules

Experimental and Theoretical Investigation of Vibrational Overtones of Glycolic Acid and Its Hydrogen Bonding Interactions with Water

A computational study of the carboxylic acid of phloroglucinol in vacuo and in water solution

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