Probing chirality recognition of protonated glutamic acid dimers by gas-phase vibrational spectroscopy and first-principles simulations

Abstract

We characterize stereospecific aspects of homochiral and heterochiral dimers of glutamic acid by infrared spectroscopy and first-principles molecular dynamics simulations.

Theoretical studies of infrared signatures of proton‐bound amino acid dimers with homochiral and heterochiral moieties

“…The relative populations and IR spectra obtained for individual conformers were used to create a composite spectrum. In order to take into account thermal broadening effects and resolution of IR sources, the absorption bands were then convoluted with Gaussian profile assuming full width at half maximum (FWHM) to be 10 cm −1 for individual conformers at 10 K and 20 cm −1 for combined spectra at room temperature . Noncovalent interaction (NCI) analysis was performed using the Multiwfn program, in order to establish the nature of the bonds that stabilize the complexes.…”

“…To the best of our knowledge, there is only one gas‐phase vibrational spectroscopy study reported, which investigated diastereomer‐specific features of proton‐bound amino acid dimers. That study was carried out for glutamic acid dimers stored in a cryogenic trap held at 10 K …”

“…10,11 To the best of our knowledge, there is only one gas-phase vibrational spectroscopy study reported, which investigated diastereomer-specific features of proton-bound amino acid dimers. That study was carried out for glutamic acid dimers stored in a cryogenic trap held at 10 K. 12 In this paper, we theoretically investigate diastereomer-specific IR signatures of proton-bound dimers with homochiral and heterochiral amino acid moieties in the IR spectral range of 1000 to 1800 cm −1 . In particular, we aim to study chiral effects in amino acid dimers associated with side chains.…”

Microhydration of protonated 5-hydroxyindole revealed by infrared spectroscopy

“…For larger hydrates (and more flexible organic chromophores), it may be rather difficult to find geometries by hand and, as a consequence, systematic computational sampling techniques such as basin-hopping or molecular dynamics should be employed. [28][29][30] Geometries, energies, and harmonic IR spectra of stable 5HIH + -W n (n = 1-3) and 5HIH + -W-Ar/N 2 (ESI †) structures are calculated at the B3LYP-D3/aug-cc-pVTZ level using GAUSSIAN09. 27,[31][32][33][34] This hybrid density functional with additive dispersion correction has proven to yield reliable results for related aromatic clusters.…”

“…The PBE0 functional is frequently used to compute properties of molecular clusters and is less empirical than B3LYP. 28,30,[44][45][46] Furthermore, singlepoint energy calculations of selected optimized structures are performed at the CC2/aug-cc-pVDZ level. Comparison to neutral and cationic s/a5HI-W clusters previously studied at the same level (B3LYP-D3/aug-cc-pVTZ) yields the effects of protonation.…”