Role of solvent dielectric constant on the enthalpy-entropy compensation in the hindered amide bond rotation

[Display omitted] •Thermodynamics of partial-double bond rotation.•Enthalpy-entropy compensation in multiple solvents.•Experimental validation using dynamic NMR. The purpose of this investigation is to determine if enthalpy-entropy compensation (EEC) is a valid concept when the experiments are perfo...

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Bibliographic Details
Published in:	Chemical physics letters Vol. 792; p. 139412
Main Authors:	Morrelli, Derek, Guerra, Jacob G., Kumar, Prarthana, Bajwa, Bhvandip, Krishnan, V.V., Maitra, Santanu
Format:	Journal Article
Language:	English
Published:	Elsevier B.V 01-04-2022
Subjects:	Dielectric constant Enthalpy-entropy compensation Nuclear Magnetic Resonance (NMR) Partial double bond Solvents Solvents Dielectric constant Partial double bond Enthalpy-entropy compensation Nuclear Magnetic Resonance (NMR)
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Summary:	[Display omitted] •Thermodynamics of partial-double bond rotation.•Enthalpy-entropy compensation in multiple solvents.•Experimental validation using dynamic NMR. The purpose of this investigation is to determine if enthalpy-entropy compensation (EEC) is a valid concept when the experiments are performed on a set of molecules in multiple solvents. Dynamic nuclear magnetic resonance (DNMR) experiments are performed on a series of analogs derived from N, N-diethyl-m-toluamide (DEET) in six different solvents of varying dielectric constant from toluene‑d8 (ε = 2.38) to dimethyl sulfoxide-d6 (ε = 46.7). The thermodynamic parameters of the restricted rotation to the solvent dielectric constant do not have a straightforward correlation relationship between them. However, the activation enthalpy and entropy of more than sixty different experimental measurements indicate that enthalpy-entropy compensation (EEC) is independent of the solvent condition with a compensation temperature of 287.81 ± 3.95 K. The results, therefore, support the broader role of EEC on the partial amide bond dynamics in the DEET analogs over the temperature range studied.
ISSN:	0009-2614 1873-4448
DOI:	10.1016/j.cplett.2022.139412