Conformational Equilibrium and Internal Dynamics of <i>E</i>-Anethole: A Rotational Study

Calabrese, Camilla; Gou, Qian; Maris, Assimo; Melandri, Sonia; Camináti, Walther

doi:10.1021/acs.jpcb.6b04883

Cited by 10 publications

(5 citation statements)

References 35 publications

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“…Experimental information on low energy conformers can be obtained by spectroscopic methods (see, e.g., Refs. [3][4][5][6][7][8][9][10]. The most powerful technique for conformational identification in the gas phase is rotational spectroscopy, which has been successfully applied in combination with laser ablation 11,12 to determine the conformations of many natural amino acids.…”

Section: Introductionmentioning

confidence: 99%

Mapping the conformational free energy of aspartic acid in the gas phase and in aqueous solution

Comitani

Rossi

Ceriotti

et al. 2017

The Journal of Chemical Physics

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Mapping the conformational free energy of aspartic acid in the gas phase and in aqueous solution The conformational free energy landscape of aspartic acid, a proteogenic amino acid involved in a wide variety of biological functions, was investigated as an example of the complexity that multiple rotatable bonds produce even in relatively simple molecules. To efficiently explore such a landscape, this molecule was studied in the neutral and zwitterionic forms, in the gas phase and in water solution, by means of molecular dynamics and the enhanced sampling method metadynamics with classical force-fields. Multi-dimensional free energy landscapes were reduced to bi-dimensional maps through the non-linear dimensionality reduction algorithm sketch-map to identify the energetically stable conformers and their interconnection paths. Quantum chemical calculations were then performed on the minimum free energy structures. Our procedure returned the low energy conformations observed experimentally in the gas phase with rotational spectroscopy [M. E. Sanz et al., Phys. Chem. Chem. Phys. 12, 3573 (2010)]. Moreover, it provided information on higher energy conformers not accessible to experiments and on the conformers in water. The comparison between different force-fields and quantum chemical data highlighted the importance of the underlying potential energy surface to accurately capture energy rankings. The combination of force-field based metadynamics, sketchmap analysis, and quantum chemical calculations was able to produce an exhaustive conformational exploration in a range of significant free energies that complements the experimental data. Similar protocols can be applied to larger peptides with complex conformational landscapes and would greatly benefit from the next generation of accurate force-fields.

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Section: Introductionmentioning

confidence: 99%

Mapping the conformational free energy of aspartic acid in the gas phase and in aqueous solution

Comitani

Rossi

Ceriotti

et al. 2017

The Journal of Chemical Physics

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“…Microwaves pectroscopy providesa ni nherently superiorr esolution of the molecular structure through the rotational constants,w hich critically depend on the mass distribution. Hence, it is an essential tool for the structuralc haracterization of conformers, [29,30] tautomers, [31] isotopologues, [32] and even enantiomers. [33] In the present case, isotopics ubstitutions enabledt he determination of the IPAS coordinates of the substituted atomsb yu sing Kraitchman's equations.…”

Section: Structural Informationmentioning

confidence: 99%

Effects of Chlorination on the Tautomeric Equilibrium of 2‐Hydroxypyridine: Experiment and Theory

Calabrese

Maris

Uriarte

et al. 2016

Chemistry A European J

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What is the most significant result of this study? This work explores the intramolecular proton transfer in the tauto-meric/conformational equilibria of ab iological model system. Previous experiments and theory gave contradictory and nonconclu-sive results due to the subtle balance of inductive and mesomeric effects. In this study,t he role of halogenation at different ring positions and the influence of the solvent on the position of complex conformational and tautomeric equilibria are explored. How did each team contribute to the work? This work stems from ac ollaboration between two research groups, triggered by the Marco Polo exchange program in which Camilla Calabrese participated as aP hD student. The presented results could not be reached without the contributions of each team. The experimental part was performed with the use of two different microwave spectrometers (one at the University of Bolo-gna (Italy) and the other one at the University of the Basque Country (Spain)). The full potential of the spectral range, resolution, and sensitivity had to be exploited for the characterization of the different tautomers and conformers of the chlorine-substituted hydroxy-pyridines in the gas phase, which presents an environment free of intermolecular interactions. The results of extensive quantum chemical calculations both in the gas and in the solvent phases have been the input for the rationalization of the effects of chlori-nation at different positions of the ring. Does the research open other avenues that you would like to investigate? The results were extremely interesting and exciting, and we intend to investigate other examples of molecules that present ac omplex conformational surface, in which substitution of atoms or groups of atoms can have adrastic influence on the stability of the various structural forms. Moreover,w ew ould like to explore the influence of such substitutions on the properties related to intermolecular interactions and reactivity. Invited for the cover of this issue are the groups of EmilioJ.C ocineroa nd Sonia Melandri at the University of PaísV asco and the University of Bologna. The image depicts different possibilities that this tautomeric equilibrium can take according to the differentp ositions of the chlorinea tom, which, in manycases,are difficult to predictapriori. Read the fulltext of the article at

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“…Laboratory rotational spectroscopy data in the microwave, millimetre and submillimetre wavelengths are necessary to perform those searches and rotational spectroscopy performed in supersonic expansions has been proved to be particularly suitable to investigate complex spectra generated by molecules (Calabrese et al ., 2016) and weakly bound molecular complexes (Velino et al ., 2004; Favero et al ., 2010). Those experiments allow us to identify multiple conformers of a flexible molecule (Vigorito et al ., 2017a), different tautomers (Sanchez et al ., 2007; Melandri et al ., 2010) as well as and different isotopologues (Calabrese et al ., 2014).…”

Section: Introductionmentioning

confidence: 99%

Searching for biosignatures by their rotational spectrum: global fit and methyl group internal rotation features of dimethylsulphoxide up to 116 GHz

Maris

Favero²,

Song³

et al. 2022

International Journal of Astrobiology

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The identification and quantification of molecules in interstellar space and atmospheres of planets in the solar systems and in exoplanets rely on spectroscopic methods and laboratory work is essential to provide the community with the spectral features needed to analyse cosmological observations. Rotational spectroscopy in particular, with its intrinsic high resolution, allows the unambiguous identification of biomolecular building blocks and biosignature gases which can be correlated with the origin of life or the identification of habitable planets. We report the extension of the measured rotational transition frequencies of dimethylsulphoxide and its 34S and 13C isotopologues in the millimetre wave range (59.6–78.4 GHz) by use of an absorption spectrometer based on the supersonic expansion technique. Hyperfine patterns related to the methyl group internal rotation were analysed in the microwave range region (6–18 GHz) with a Pulsed Jet Fourier Transform spectrometer at extremely high resolution (2 kHz) and reliable predictions up to 116 GHz are provided. The focus on sulphur-bearing molecules is motivated by the fact that sulphur is largely involved in the intra- and inter-molecular hydrogen bonds in proteins and although it is the 10th most abundant element in the known Universe, understanding its chemistry is still a matter of debate. Moreover, sulphur-bearing molecules, in particular dimethylsulphoxide, have been indicated as possible biosignature gases to be monitored in the search of habitable exoplanets.

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Conformational Equilibrium and Internal Dynamics of E-Anethole: A Rotational Study

Cited by 10 publications

References 35 publications

Mapping the conformational free energy of aspartic acid in the gas phase and in aqueous solution

Mapping the conformational free energy of aspartic acid in the gas phase and in aqueous solution

Effects of Chlorination on the Tautomeric Equilibrium of 2‐Hydroxypyridine: Experiment and Theory

Searching for biosignatures by their rotational spectrum: global fit and methyl group internal rotation features of dimethylsulphoxide up to 116 GHz

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