Chirality Recognition in Menthol and Neomenthol: Preference for Homoconfigurational Aggregation

Albrecht, Merwe; Will, Jan; Suhm, Martin A.

doi:10.1002/anie.201001565

Cited by 27 publications

(36 citation statements)

References 23 publications

(45 reference statements)

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“…[4] In the solid, all hydrogen bonds are intermolecular. [30] Thek ey to unambiguous symmetric dimer detection is ac ombination of linear Fourier transform infrared (FTIR) spectroscopy and linear Raman scattering based on intense 532 nm excitation, [31][32][33] both coupled to slit jet expansions of ethylene glycol in an excess of helium carrier gas to adiabatically cool and dimerize the diol without environmental distortion. Thel inearity and non-selectivity of the complementary techniques ensures that the relative abundance of different species can be judged reliably.O nly atomic species are invisible to this spectroscopic combination.…”

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confidence: 99%

A Symmetric Recognition Motif between Vicinal Diols: The Fourfold Grip in Ethylene Glycol Dimer

2016

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confidence: 99%

A Symmetric Recognition Motif between Vicinal Diols: The Fourfold Grip in Ethylene Glycol Dimer

2016

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“…A single signal attributable to dimers (D) is observed near 3513 cm −1 at a low signal‐to‐noise ratio despite probing a 600 mm long expansion zone (see Figure S1) . The dimer signal was optimized by employing a 10 mm double slit nozzle at elevated temperature, which allows for a higher monomer concentration. The spectrum, in which the dimer signal now exceeds the monomer signal, is displayed in Figure .…”

Section: Figurementioning

confidence: 59%

“…The key to unambiguous symmetric dimer detection is a combination of linear Fourier transform infrared (FTIR) spectroscopy and linear Raman scattering based on intense 532 nm excitation, both coupled to slit jet expansions of ethylene glycol in an excess of helium carrier gas to adiabatically cool and dimerize the diol without environmental distortion. The linearity and non‐selectivity of the complementary techniques ensures that the relative abundance of different species can be judged reliably.…”

Section: Figurementioning

confidence: 99%

A Symmetric Recognition Motif between Vicinal Diols: The Fourfold Grip in Ethylene Glycol Dimer

2016

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Ethylene glycol has atransiently chiral, asymmetric global minimum structure,b ut it favors ah ighly symmetric, achiral dimer arrangement which has not been considered or found in previous quantum-chemical studies.C omplementary FTIR and Raman spectroscopyinsupersonic jets allows for the detection and straightforwarda ssignment of this four-fold hydrogen-bonded dimer,w hich introduces an interesting supramolecular binding motif for vicinal diols and provides astrong case for transient chirality synchronization.Carbohydrates are among the most versatile molecules employed by nature in molecular recognition processes and their biomimetic detection is challenging.[1] When reducing their molecular complexity to am inimum, one naturally arrives at vicinal diols.A mong them, the simplest representative ethylene glycol has even been detected in interstellar space.[2] Ethylene glycol or 1,2-ethanediol is ap articularly valuable model system for the study of multiple hydrogenbonded dimers and carbohydrate interactions, [3] because it allows for av ast range of quantum-chemical options to be explored. Indeed, the question of its preferred dimer structure has been addressed repeatedly by theory, [4][5][6] but not by experimental techniques.B ecause of the torsional flexibility of ethylene glycol, there are several possibilities how the four OH groups of the dimer can engage in hydrogen bonds.None of the previously proposed structures involves more than three hydrogen bonds among these OH groups. [4][5][6][7][8][9][10][11] We present unambiguous combined IR and Raman spectroscopic evidence that ethylene glycol in fact forms an S 4 -symmetric and thus non-polar and achiral dimer with four equivalent hydrogen bonds.U sing Gaussian 09, [12] an extensive search of the intermolecular potential-energy hypersurface at B3LYP-D3(BJ)/6-311 + G(2d,p) level (in short B3LYP) confirms that this structure wins over all triply hydrogen-bonded dimer structures by as ubstantial energy margin.Thet wo lowest monomer structures found at the harmonically zero-point energy-corrected B3LYP level are depicted in Figure 1. They have in common a gauche OCCO backbone,aweakly hydrogen-bonded OH group, and af ree OH group pointing in trans (M) or gauche (M') direction relative to the CÀCb ackbone.T hese monomer conformations are chiral and differ only by 1.4 kJ mol À1 at B3LYP level, making both of them potentially observable in aseeded adiabatic jet expansion. They have been investigated previously in much detail, [13][14][15][16][17][18][19][20][21][22][23][24][25] mostly by microwave spectroscopy, [13][14][15][16][17][18][19][20] and experimental estimates for their energy difference are rather close to our theoretical prediction, with 1.4(4) and 2.5(5) kJ mol À1 . [16,20] In jet experiments,t ypically only Mi so bserved in substantial abundance because of efficient conformational relaxation, [18] whereas at room temperature,M ' is also populated. Donor-acceptor OH torsional tunneling splits the levels by 0.2 and 0.05 cm À1 , respectively. ...

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“…Information gained from gas‐phase experiments allows isolating the contact pairs responsible from chiral discrimination and disentangling the specific interactions within the molecule/ligand complex from the contribution of the solvent. Attempts at obtaining data at the microscopic level are pursued both from the stability and spectroscopy points of view, for both neutral and ionic systems …”

Section: Introductionmentioning

confidence: 99%

“…Attempts at obtaining data at the microscopic level are pursued both from the stability and spectroscopy points of view, for both neutral and ionic systems. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] In particular, ion traps offer a very appropriate laboratory for studying the interactions within a protonated or deprotonated chiral pair, without the influence of the solvent. 24,25 Mass spectrometry approaches of chiral recognition in ionic complexes have been the subject of several review articles.…”

Section: Introductionmentioning

confidence: 99%

Mass Spectrometry Study and Infrared Spectroscopy of the Complex Between Camphor and the Two Enantiomers of Protonated Alanine: The Role of Higher‐Energy Conformers in the Enantioselectivity of the Dissociation Rate Constants

et al. 2013

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The properties of the protonated complexes built from S camphor and R or S alanine were studied in a Paul ion trap at room temperature by collision-induced dissociation (CID) and infrared multiple-photon dissociation spectroscopy (IRMPD), as well as molecular dynamics and ab initio calculations. While the two diastereomer complexes display very similar vibrational spectra in the fingerprint region, in line with similar structures, and almost identical calculated binding energies, their collision-induced dissociation rates are different. Comparison of the IRMPD results to computed spectra shows that the SS and SR complexes both contain protonated alanine strongly hydrogen-bonded to the keto group of camphor. The floppiness of this structure around the NH⁺...O=C hydrogen bond results in a complex potential energy surface showing multiple minima. Calculating the dissociation rate constant within the frame of the transition state theory shows that the fragmentation rate larger for the heterochiral SR complex than the homochiral SS complex can be explained in terms of two almost isoenergetic low-energy conformers in the latter that are not present for the former.

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Chirality Recognition in Menthol and Neomenthol: Preference for Homoconfigurational Aggregation

Abstract: Cool chirality: L‐Menthol (see ball‐and‐stick model), a most important fragrance, is characterized in terms of its conformation, selective aggregation, and sublimation. The data indicate a preference for homoconfigured aggregates.

Cited by 27 publications

References 23 publications

A Symmetric Recognition Motif between Vicinal Diols: The Fourfold Grip in Ethylene Glycol Dimer

A Symmetric Recognition Motif between Vicinal Diols: The Fourfold Grip in Ethylene Glycol Dimer

A Symmetric Recognition Motif between Vicinal Diols: The Fourfold Grip in Ethylene Glycol Dimer

Mass Spectrometry Study and Infrared Spectroscopy of the Complex Between Camphor and the Two Enantiomers of Protonated Alanine: The Role of Higher‐Energy Conformers in the Enantioselectivity of the Dissociation Rate Constants

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