A density functional theory study of the conformational properties of 1,2-ethanediamine: protonation and solvent effects

Abstract

The structures and the conformational energies of nonprotonated, monoprotonated and diprotonated 1,2-ethanediamine have been investigated through density functional theory. The relative performance of local and gradient-corrected functionals is discussed. The existence of hydrogen-bond formation has been determined with electron localisation function calculations. Proton anities for nonprotonated and monoprotonated 1,2-ethanediamine have been calculated and are in agreement with experimental data. The in¯uence of solvation has been accounted for through the selfconsistent isodensity polarisable continuum model. The results for the nonprotonated conformers show that solvation stabilises those conformers which have the lone pair in an antiperiplanar conformation. Solvation of the monoprotonated conformer stabilises signi®cantly the``anti'' conformation, which is unstable in the gas phase. For the di-protonated species, solvation stabilises slightly the gauche conformer, which is unstable in the gas phase.

An Ethylenediamine‐based Switch to Render the Polyzwitterion Cationic at Tumorous pH for Effective Tumor Accumulation of Coated Nanomaterials

“…The large difference may be explained by the restricted conformation of the di‐protonated state, that is, anti ‐form, which is presumably due to the electrostatic repulsion of two protonated amines, along with butane effect as steric hindrance . On the other hand, the mono‐protonated state is likely to take a gauche conformation . Thus, ethylenediamine moiety would suffer from thermodynamic penalty toward the di‐protonation; as a result, ethylenediamine moiety in PGlu(DET) was mono‐protonated at pH 7.4 ( α =55), and the di‐protonation was initiated around tumorous pH in a stepwise manner.…”

First-Principles Study of the Reaction between Fluorinated Graphene and Ethylenediamine

“…However, the reaction energy barrier of the process is generally high. EDA has the characteristics of simple structure, strong reducibility, and rotational isomerism of the molecule [25]. The electron-diffraction data and the quantum chemical calculation indicate that EDA is mainly in the gauche conformation (the N–C–C–N dihedral angle is in the range of 64 ± 4°) [26,27] in the gaseous phase.…”

Spectroscopy of Proton Coordination with Ethylenediamine

“…Protonated ethylenediamine has been studied previously with mass spectrometry − and computational chemistry. , From proton transfer reactions in the gas phase, it is known that diamines display a larger proton affinity than monoamines of comparable size. ,,, Additionally, large negative entropy changes indicate the formation of cyclic intramolecular hydrogen bonds. The (negative) enthalpy of ring formation −Δ H ° ring form for ethylenediamine has been estimated to be greater than 9.7 kcal mol –1 .…”