Development of a Virtual Spectrometer for Chiroptical Spectroscopies: The Case of Nicotine

Egidi, Franco; Bloino, Julien; Cappelli, Chiara; Barone, Vincenzo

doi:10.1002/chir.22200

Cited by 22 publications

(34 citation statements)

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“…In line with previous work of some of the present authors, [28][29][30][31][32][33] we aim to develop accurate yet user-friendly strategies for the calculation of RROA spectra of complex systems, also interacting with external complex environments. Here, we start our investigation on such a field, by addressing the problem of origin invariance in RROA, a fundamental topic which, to the best our knowledge, has never been directly addressed.…”

Section: Introductionmentioning

confidence: 73%

Origin invariance in vibrational resonance Raman optical activity

Vidal

Egidi

Barone

et al. 2015

The Journal of Chemical Physics

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A theoretical investigation on the origin dependence of the vibronic polarizabilities, isotropic and anisotropic rotational invariants, and scattering cross sections in Resonance Raman Optical Activity (RROA) spectroscopy is presented. Expressions showing the origin dependence of these polarizabilities were written in the resonance regime using the Franck-Condon (FC) and Herzberg-Teller (HT) approximations for the electronic transition moments. Differently from the far-from-resonance scattering regime, where the origin dependent terms cancel out when the rotational invariants are calculated, RROA spectrum can exhibit some origin dependence even for eigenfunctions of the electronic Hamiltonian. At the FC level, the RROA spectrum is completely origin invariant if the polarizabilities are calculated using a single excited state or for a set of degenerate states. Otherwise, some origin effects can be observed in the spectrum. At the HT level, RROA spectrum is origin dependent even when the polarizabilities are evaluated from a single excited state but the origin effect is expected to be small in this case. Numerical calculations performed for (S)-methyloxirane, (2R,3R)-dimethyloxirane, and (R)-4-F-2-azetidinone at both FC and HT levels using the velocity representation of the electric dipole and quadrupole transition moments confirm the predictions of the theory and show the extent of origin effects and the effectiveness of suggested ways to remove them.

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Section: Introductionmentioning

confidence: 73%

Origin invariance in vibrational resonance Raman optical activity

Vidal

Egidi

Barone

et al. 2015

The Journal of Chemical Physics

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“…In particular, the first test case concerns a rigid small molecule, methyloxirane in aqueous solution, which has been reported to be particularly challenging for continuum solvent methodologies. The second example refers to a flexible molecule of medium size, nicotine, again in aqueous solution, which has as well been taken as reference for testing the performance of continuum solvation models . For each case, the comparison between the QM/FQ/PCM and both experimental data and continuum solvation approaches is proposed, the latter to especially evidence the role of short‐range specific interactions with respect to long‐range bulk effects.…”

Section: Some Selected Examplesmentioning

confidence: 99%

“…Also, it has been amply demonstrated that the presence of the external environment may affect not only the absolute value but also especially the sign of the chiroptical response . Therefore, the use of either the most accurate levels of calculations may be ineffective if not accompanied by reliable methodologies to take into account environmental effects …”

Section: Introductionmentioning

confidence: 99%

“…Nowadays, the large majority of the calculations performed to support the assignment of the chiral absolute configuration exploit such approaches, coupled to a QM description of the target system. QM/continuum solvation models for chiroptical properties have been recently reviewed: the interested reader can find a comprehensive discussion in recent literature . However, as already mentioned in the Introduction, they suffer from serious limitations.…”

Section: Introductionmentioning

confidence: 99%

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Integrated QM/polarizable MM/continuum approaches to model chiroptical properties of strongly interacting solute–solvent systems

Cappelli

2016

Int J of Quantum Chemistry

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140

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Solvent effects on chiroptical properties and spectroscopies can be huge, and affect not only the absolute value but the sign of molecular chiroptical responses. Therefore, the definition of reliable theoretical models and computational protocols to calculate chiroptical responses and assist the assignment of the chiral absolute configuration cannot overlook the effects of the surrounding environment. Continuum solvation methodologies are successful in case of weakly interacting solute-solvent couples, whereas in case of strongly interacting systems, such as those dominated by explicit hydrogen bonding interaction, a change of strategy is required to gain a reliable modeling.In this review, a recently developed integrated Quantum-Mechanical/Polarizable molecular mechanics (MM)/polarizable continuum model (PCM) method is discussed, which combines a fluctuating charge approach to the MM polarization with the PCM. Its theoretical fundamentals, and issues related to the calculation of chiroptical responses are summarized, and the application to few representative test cases in aqueous solution is discussed.aqueous solutions, chirality, polarizable embedding, solvent effects, quantum mechanical/molecular mechanics | I N T R O D U C T I O NThe calculation of chiroptical properties and chiral spectra by means of Quantum-Mechanical (QM) methods [1][2][3][4][5] is a mature research field.Many theoretical developments have been reported in the literature, focusing on the different aspects (accuracy in the description of the molecular Hamiltonian, choice of the basis set, inclusion of environmental effects) [3,[6][7][8][9] which may contribute to reach an accurate description of chirality. The definition of accurate protocols is nowadays accompanied by several applications, which demonstrate that a significant level of accuracy is accessible, so that QM calculations are universally accepted as a powerful methodology to assist the determination of the molecular absolute configuration.[10]In case of standard (non-chiral) spectroscopies, the most relevant information which is extracted from spectra is mainly related to peak positions (energies), whereas peak intensities play a secondary role. This is reflected in the computational methodologies which have been developed so far, which are mainly interested in getting an accurate reproduction of peak positions (infrared/Raman wavenumbers, UV-Vis transition energies, NMR chemical shieldings, etc.), reserving instead much less attention to spectral intensities. [11][12][13] In case of chiroptical properties/spectroscopies, an opposite situation occurs, in fact not only the absolute value but also especially the sign of the spectroscopic response is the most relevant information taken from the spectra. This feature makes chiroptical properties among the most challenging for theoretical models, and the difficulties in their accurate modeling are further increased by that fact that they are formally mixed electricmagnetic properties, where the effects of both the fields are ...

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“…The fully ab initio VPT2 88 approach allows also inclusion of non-specific solvent effects by means of the polarizable continuum model (PCM) essentially without any additional cost 91 , and has been also extended to take into account non-equilibrium solvent effects on vibrational (e.g. IR or VCD) transition intensities [92][93][94] .…”

Section: Introductionmentioning

confidence: 99%

Dispersion corrected DFT approaches for anharmonic vibrational frequency calculations: nucleobases and their dimers

Fornaro

Biczysko

Monti

et al. 2014

Phys. Chem. Chem. Phys.

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101

113

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Computational spectroscopy techniques have become in the last years effective means to analyze and assign infrared (IR) spectra for molecular systems of increasing dimensions and in different environments. However, transition from compilations of harmonic data to full anharmonic simulations of spectra is still under way. The most promising results for large systems have been obtained, in our opinion, by perturbative vibrational approaches based on potential energy surfaces computed by hybrid (especially B3LYP) density functionals and medium size (e.g. SNSD) basis sets. In this framework, we are actively developing a comprehensive and robust computational protocol aimed to a quantitative reproduction of the spectra of nucleic acid bases complexes and their adsorption on solid supports (organic/inorganic). In this contribution we report the essential results of the first step devoted to isolated monomers and dimers. It is well known that in order to model the vibrational spectra of weakly bound molecular complexes dispersion interactions should be taken into proper account. In this work, we have chosen two popular and inexpensive approaches to model dispersion interaction, namely the semi-empirical dispersion correction (D3) and pseudopotential based (DCP) methodologies both in conjunction with the B3LYP functional. These have been used for simulating fully anharmonic IR spectra of nucleobases and their dimers through generalized second order vibrational perturbation theory (GVPT2). We have studied, in particular, isolated adenine, hypoxanthine, uracil, thymine and cytosine, the hydrogen-bonded and stacked adenine and uracil dimers, and the stacked adenine-naphthalene heterodimer. Anharmonic frequencies are compared with standard B3LYP results and experimental findings, while the computed interaction energies and structures of complexes are compared to the best available theoretical estimates.

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Development of a Virtual Spectrometer for Chiroptical Spectroscopies: The Case of Nicotine

Cited by 22 publications

References 58 publications

Origin invariance in vibrational resonance Raman optical activity

Origin invariance in vibrational resonance Raman optical activity

Integrated QM/polarizable MM/continuum approaches to model chiroptical properties of strongly interacting solute–solvent systems

Dispersion corrected DFT approaches for anharmonic vibrational frequency calculations: nucleobases and their dimers

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