Identification of ion pairs in solution by IR spectroscopy: crucial contributions of gas phase data and simulations

Habka, Sana; Véry, Thibaut; Donon, Jérémy; Vaquero-Vara, Vanesa; Tardivel, B.; Charnay‐Pouget, Florence; Mons, Michel; Aitken, David J.; Brenner, V.; Gloaguen, Éric

doi:10.1039/c9cp00700h

Cited by 25 publications

(43 citation statements)

References 48 publications

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“…R2PI-UV spectra of the ion pairs (Fig. 1) all consists of one main transition, revealing that the conformational distributions of these systems are dominated by a single conformer, identified by conformer-selective IR spectroscopy and frequency calculations at the DFT-D level 13 (Fig. 2 left and Fig.…”

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confidence: 96%

Electronic Stark Effect in Isolated Ion Pairs

Donon

Habka

Vaquero-Vara

et al. 2019

J. Phys. Chem. Lett.

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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

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confidence: 96%

Electronic Stark Effect in Isolated Ion Pairs

Donon

Habka

Vaquero-Vara

et al. 2019

J. Phys. Chem. Lett.

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“…These sophisticated approaches can typically reach an accuracy of 20 cm -1 and sometimes down to 5 cm -1 for dipeptides. 73,219,355 For coupled modes, it is not possible to define mode-dependent scaling factors (e.g. multiple OH stretch modes), 142 and more refined anharmonic calculations become necessary to describe vibrational resonances or simply have access to intensities of overtones and combination bands, and thus increase prediction accuracy.…”

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confidence: 99%

Neutral Peptides in the Gas Phase: Conformation and Aggregation Issues

et al. 2020

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Combined IR and UV laser spectroscopic techniques in molecular beams merged with theoretical approaches have proven to be an ideal tool to elucidate intrinsic structural properties on a molecular level. It offers the possibility to analyze structural changes by successively adding aggregation partners and thus an environment to a molecule. By this, it further makes these techniques a valuable starting point for a bottom-up approach in understanding the forces shaping larger molecular systems. This bottomup approach was successfully applied to neutral amino acids starting around the 1990s. Ever since experimental and theoretical methods developed further and investigations could be extended to larger peptide systems. Beyond, the review gives an introduction to secondary structures and experimental methods as well as a summary on theoretical approaches. Vibrational frequencies being characteristic probes of molecular structure and interactions are especially addressed. Archetypal biologically relevant secondary structures investigated by molecular beam spectroscopy are described and the influences of specific peptide residues on conformational preferences as well as the competition between secondary structures are discussed. Important influences like microsolvation or aggregation behaviour are presented. Beyond the linear α-peptides the main results of structural analysis on cyclic systems as well as on β-and γ-peptides are summarized. Overall, this contribution addresses current aspects of molecular beam spectroscopy on peptides and related species and provides molecular level insights into manifold issues of chemical and biochemical relevance. 45) , non-protected (cf. e.g. 46-48) and protected amino acids (cf. e.g. 49) up to dipeptide models (cf. e.g. 50).In this context, laser spectroscopic techniques combining IR and UV excitations, that one can consider as belonging to the so-called 'action spectroscopies', provide an isomer-selective method of choice to tackle the 87 ) or immunoglobulins (cf. e.g. 88), but they are also found in context with neurodegenerative diseases (cf. e.g. [89][90][91][92][93][94][95] and Section 12). A further structure associated with these diseases (cf. e.g. 96 ) is the β-helix, which presents a protein structure of several parallel β-strands in a helical arrangement with a frequently repetitive amino acid sequence. The structure is stabilized by H-bonds, sometimes ionic interactions or so called protein-protein interactions, which e.g. include electrostatic and hydrophobic effects. Further aspects of peptide structure in gas phase The role of protection groupsWith the unmodified N-and C-terminus amino acids and peptides can exhibit strong preferences for intramolecular H-bonds involving the N-and C-terminus, and can also form intermolecular H-bonds leading to polymer chains. Nevertheless, in a context where the description of the properties of a protein or a long peptide (with respect to its backbone) by smaller peptides is targeted, the introduction of protecting groups at the N-and...

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“…Numerical harmonic frequency calculations were performed at the same level. Harmonic frequencies, f 0 th , were further corrected to obtain mode-dependent 34 frequencies, f th , scaled by two linear functions, 35,36 f th = 0.9272 f 0 th + 137.9 cm −1 for the (CO 2 − ) anti stretch, and f th = 1.1431 f 0 th − 164.3 cm −1 for the (CO 2 − ) sym stretch, determined previously 37 from a set of carboxylate-containing conformers assigned in the literature. Electric field calculations were performed at the RI-B97-D3(BJ)/def2-QZVPP level 29,31,38,39 on RI-B97-D3(BJ)-abc/dhf-TZVPP optimized structures, unless specified otherwise (Turbomole options detailed in ESI † ).…”

Section: Methodsmentioning

confidence: 99%