Conformations, energies, and intramolecular hydrogen bonds in dicarboxylic acids: Implications for the design of synthetic dicarboxylic acid receptors

Abstract

The various conformers of the dicarboxylic acids HO2C--(CH2)n--CO2H, n = 1-4, were obtained using density functional methods (DFT), both in the gas phase and in the aqueous phase using a polarized continuum model (PCM). Several new conformers were identified, particularly for the two larger molecules glutaric (n = 3) and adipic acid (n =4). The PCM results show that the stability of most conformers were affected, many becoming unstable in the aqueous phase; and the energy ordering of conformers is also different. The results suggest that conformational preferences could be important in determining the design and stability of appropriate synthetic receptors for glutaric and adipic acid. Geometry changes between gas and aqueous phases were most marked in those conformers containing an intramolecular hydrogen bond. Additional calculations have probed the strength of intramolecular hydrogen bonds in these dicarboxylic acids. In the cases of glutaric and adipic acid, the strength of the intramolecular hydrogen bond were estimated to be around 28-29 kJ/mol, without any vibrational energy correction. The intramolecular hydrogen bond energies in malonic and succinic acid were also estimated from the calculated H-bond distances using an empirical relationship. Intramolecular H-bond redshifts of 170-250 cm(-1) have been estimated from the results of the harmonic frequency analyses.

Production of Biodegradable Palm Oil-Based Polyurethane as Potential Biomaterial for Biomedical Applications

“…Glutaric acid [(CH 2 )n(COOH) 2, n = 3] in the present work as compared to malonic acid [(CH 2 )n(COOH) 2, n = 1], appears to be the reason for the enhanced water uptake of the polyurethanes. It has been reported that the most stable conformer (∆G = 0) of glutaric acid in water has greater dipole moment ( p glutaric = 4.66 D) than that of malonic acid conformer in water ( p glutaric = 3.68 D) [ 70 ]. Glutaric acid has a greater dipole moment, indicating that the hydrogen bond acceptor C=O has higher electronegativity than that of malonic acid, hence polyurethanes comprising of glutaric acid in the soft segment are hypothesized to have stronger hydrogen bonding energy, thus exhibiting superior water uptake during the enzymatic degradation test ( Figure 9 ).…”

Criegee Intermediate Reactions with Carboxylic Acids: A Potential Source of Secondary Organic Aerosol in the Atmosphere

“…In malonic acid, the labile, non-H-bonded acidic hydrogen could participate in reaction with a Criegee intermediate, whereas larger dicarboxylic acids have two labile acidic hydrogens, but lower dipole moments. 32 Thus, the reactivity of the dicarboxylic acids is expected to be similar to regular carboxylic acids. However, dicarboxylic acids have low vapour pressures; for example, Malonic acid has a vapour pressure of 9.8  10 -7…”

Ala-504 is a determinant of substrate binding affinity in the mouse Na+/dicarboxylate cotransporter

“…Similar to the PepT1 substrates, the dicarboxylates transported by NaDC1 are flexible molecules that can adopt multiple stable conformations [22,23]. The differences in the substrate binding pockets between the rabbit and mouse NaDC1 are probably the result of differences in substrate:protein contact points or differences in the size of the substrate binding pocket.…”