Signatures of counter-ion association and hydrogen bonding in vibrational circular dichroism spectra

Nicu, Valentin Paul; Heshmat, Mojgan; Baerends, Evert Jan

doi:10.1039/c0cp02701d

Cited by 26 publications

(28 citation statements)

References 30 publications

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“…First, because Slater-type orbitals are used as basis functions in ADF and, as such, all matrix elements are calculated numerically,f requency calculations using hybrid exchange-correlation functionals like B3LYP are extremelye xpensive. Second, as shown, [20,34,[48][49][50] the VCD (also VA)s pectra computed by using the BP86 and OLYP functionals reproduce the experimental spectra as well as those computed by using B3LYP.Third, the VA and VCD spectra computed for DHQD at the BP86 and OLYP levels of theory are overall rather similar to the B3LYP spectra computed in reference [18] (see Figure 10) for the quinidine molecule (which structurally is very similartoD HQD).…”

Section: Computational Detailssupporting

confidence: 65%

Interplay of Exciton Coupling and Large‐Amplitude Motions in the Vibrational Circular Dichroism Spectrum of Dehydroquinidine

Nicu

Domingos

Strudwick

et al. 2015

Chemistry A European J

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A detailed analysis of the computed structure, energies, vibrational absorption (VA) and circular dichroism (VCD) spectra of 30 low-energy conformers of dehydroquinidine reveals the existence of families of pseudo-conformers, the structures of which differ mostly in the orientation of a single O-H bond. The pseudo-conformers in a family are separated by very small energy barriers (i.e., 1.0 kcal mol(-1) or smaller) and have very different VCD spectra. First, we demonstrate the unreliable character of the Boltzmann factors predicted with DFT. Then, we show that the large differences observed between the VCD spectra of the pseudo-conformers in a family are caused by large-amplitude motions involving the O-H bond, which trigger the appearance/disappearance of strong VCD exciton-coupling bands in the fingerprint region. This interplay between exciton coupling and large-amplitude-motion phenomena demonstrates that when dealing with flexible molecules with polar bonds, vibrational averaging of VCD spectra should not be neglected. In this regard, the dehydroquinidine molecule considered here is expected to be a typical example and not the exception to the rule.

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Section: Computational Detailssupporting

confidence: 65%

Interplay of Exciton Coupling and Large‐Amplitude Motions in the Vibrational Circular Dichroism Spectrum of Dehydroquinidine

Nicu

Domingos

Strudwick

et al. 2015

Chemistry A European J

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“…For dimers larger and more robust rotatory strengths are obtained. As it has been pointed out very recently by Nicu et al 56 the enhancement of VCD signal is expected when hydrogen bonds are present in the sample. Therefore, for practical VCD measurements, if bulky groups do not block dimer formation, the comparison of the computed spectrum of the dimers with the experimental spectrum recorded in relatively concentrated (B0.1 mol dm À1 ) solutions is highly recommended.…”

Section: Discussionmentioning

confidence: 80%

Effects of strong and weak hydrogen bond formation on VCD spectra: a case study of 2-chloropropionic acid

Góbi

Vass

Magyarfalvi

et al. 2011

Phys. Chem. Chem. Phys.

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The vibrational circular dichroism (VCD) spectrum of S-(-) and R-(+)-2-chloropropionic acid is thoroughly analyzed. Besides the VCD spectrum of the monomer, the dimers (stabilized by strong hydrogen bonds) and the 2-chloropropionic acid-CHCl(3) complexes (stabilized by a weak hydrogen bond) are studied both experimentally (in solution and in low-temperature Ar matrix) and by quantum chemical computations. It is shown that dimer formation drastically changes, and even weak complex formation can also substantially affect the overall shape of the VCD spectrum. The present and previous results can be generalized for the practice of absolute configuration determination of carboxylic acids by VCD spectroscopy. For these measurements, if bulky groups do not block dimer formation, comparison of the computed spectra of the dimers with the experimental spectra recorded in relatively concentrated (∼0.1 mol dm(-3)) solutions is suggested. Our study also shows that due to the stabilization of monomers and/or the formation of weak complexes, the VCD spectrum recorded in CHCl(3) is more complex and, like in the present case, can have a lower intensity than that of the spectrum recorded in CCl(4). Therefore, if solubility allows, CCl(4) is a much preferred solvent over CHCl(3).

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“…Then, the observed differences in Figures 5 and 6 are a consequence of the fact that the components of the APTs and AATs of the atoms that are involved in (or in the vicinity of) the intermolecular bonds have different values in the molecular complexes compared to the isolated molecules. 10 As shown in ref 10, the transfer of charge, determined by the donor−acceptor interaction associated with intermolecular hydrogen bond formation, affects significantly the electronic contributions of the APTs and AATs of the atoms involved in (or in the vicinity of) the intermolecular bonds. These electronic perturbations of the APTs and AATs can easily destroy the fine balance between the nuclear and electronic contributions to the electric and magnetic dipole transition moments (which most often have comparable magnitudes but Figure 5.…”

Section: ■ Molecular Structuresmentioning

confidence: 99%

Understanding Solvent Effects in Vibrational Circular Dichroism Spectra: [1,1′-Binaphthalene]-2,2′-diol in Dichloromethane, Acetonitrile, and Dimethyl Sulfoxide Solvents

2012

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We present a combined experimental and computational investigation of the vibrational absorption (VA) and vibrational circular dichroism (VCD) spectra of [1,1'-binaphthalene]-2,2'-diol. First, the sensitive dependence of the experimental VA and VCD spectra on the solvent is demonstrated by comparing the experimental spectra measured in CH(2)Cl(2), CD(3)CN, and DMSO-d(6) solvents. Then, by comparing calculations performed for the isolated solute molecule to calculations performed for molecular complexes formed between solute and solvent molecules, we identify three main types of perturbations that affect the shape of the VA and VCD spectra when going from one solvent to another. These sources of perturbations are (1) perturbation of the Boltzmann populations, (2) perturbation of the electronic structure, and (3) perturbation of the normal modes.

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Signatures of counter-ion association and hydrogen bonding in vibrational circular dichroism spectra

Cited by 26 publications

References 30 publications

Interplay of Exciton Coupling and Large‐Amplitude Motions in the Vibrational Circular Dichroism Spectrum of Dehydroquinidine

Interplay of Exciton Coupling and Large‐Amplitude Motions in the Vibrational Circular Dichroism Spectrum of Dehydroquinidine

Effects of strong and weak hydrogen bond formation on VCD spectra: a case study of 2-chloropropionic acid

Understanding Solvent Effects in Vibrational Circular Dichroism Spectra: [1,1′-Binaphthalene]-2,2′-diol in Dichloromethane, Acetonitrile, and Dimethyl Sulfoxide Solvents

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