Effect of Caffeine on the Physicochemical Properties of Neurotransmitter GABA: Thermodynamic and Theoretical Approach

• Published in: Journal of chemical and engineering data 2019-09, Vol.64 (9), p.3919-3932
• Main Authors: Kaur, Navalpreet, Sharma, Punita, Banipal, Tarlok S, Banipal, Parampaul K, Aggarwal, Neha
• Format: Article
• Language: English
• ISSN: 0021-9568; 1520-5134
• DOI: 10.1021/acs.jced.9b00327

The density, ρ, and the speed of sound, u, of γ-aminobutyric acid (GABA) in water and in (0.005, 0.01, 0.02, 0.04, and 0.06) mol·kg–1 aqueous caffeine (CAF) solutions were measured at temperatures, T = (293.15–318.15) K and P = 0.1 MPa. The measured data have been used to calculate apparent molar volumes at infinitesimal concentration (V 2,ϕ o), apparent molar isentropic compressibility (K 2,ϕ o), the corresponding transfer parameters, and other derived properties. The negative transfer values suggest the dominance of hydrophobic interactions and the structure-breaking tendency of CAF molecules. UV–visible spectroscopic studies have been carried out, and the shifts in the absorption spectra signify the role of hydrogen-bonding interactions. The structures of GABA and CAF have also been optimized in gas phase and solution phase by employing density functional theory at B3LYP/6-31+G* theoretical level, and the H-bond interactions between the two molecules have been studied. It is observed that there are strong H-bond interactions between GABA and CAF.