The Electronic Circular Dichroism of Nicotine in Aqueous Solution: A Test Case for Continuum and Mixed Explicit-Continuum Solvation Approaches

Egidi, Franco; Russo, Rosario; Carnimeo, Ivan; D’Urso, Alessandro; Mancini, Giordano; Cappelli, Chiara

doi:10.1021/jp510542x

Cited by 34 publications

(68 citation statements)

References 70 publications

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“…Also, implicit solvation is accurate enough to reproduce the OR and other chiroptical spectroscopies of aqueous solutions of (S)‐ N ‐acetylproline amide, where explicit solute–solvent interactions are in principle expected. A different situation occurs for nicotine in aqueous solution, where the inclusion of specific solvation effects leads to an improvement in calculated Electronic Circular Dichroism (ECD) spectra, though continuum solvation yields qualitatively correct results, as well as reasonable OR values in isopropanol …”

Section: Introductionmentioning

confidence: 99%

“…Recent studies have demonstrated that such a limitation can be successfully overcome by moving to QM/MM/continuum approaches, such as the recently developed fully polarizable QM/FQ/PCM method with nonperiodic boundary conditions, which includes polarization effects in the classical MM portion by means of fluctuating charges (FQ) and resorts to a continuum PCM treatment of the outer solvation shell. In particular in this model the solvated molecular system is decomposed in three layers, in a multiscale fashion (Figure ).…”

Section: Introductionmentioning

confidence: 99%

“…The QM/FQ/PCM approach has recently been extended to treat the evaluation of analytical first and second derivatives, response equations, magnetic perturbations with gauge including atomic orbitals (GIAOs), excitation energies (at the TDDFT and EOM‐CCSD levels of theory), and excitation energy gradients . Therefore, most chiroptical responses can be calculated . In this section, the physical and computational aspects of this model in connection with the calculation of chiroptical properties are briefly presented, whereas selected examples, showing its potentialities are reported in a forthcoming section.…”

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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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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“…The equilibrium between the charge interactions and the differences in the atomic electronegativities represents the physical basis of the electronegativity equalization principle, which defines, in turn, the FQ model. The QM/FQ model has recently been extended by some of the present authors to the evaluation of analytical first and second derivatives, response equations, magnetic perturbations with gauge independent atomic orbitals (GIAO) and excitation energies at the equation of motion coupled cluster singles and doubles (EOM‐CCSD) level, and has been shown to give remarkable agreement with experimental findings in various applications in the field of computational spectroscopy . In the polarizable QM/FQ approach, the interaction energy is analogous to eq.…”

Section: Theorymentioning

confidence: 72%

“…As a matter of fact, full QM approaches become in this case not only unfeasible unless resorting to oversimplified (e.g., semiempirical) methods, but also quite illogical, whenever the interest is not to reach a detailed description of the whole solvent, but, rather, of the tuning of solute structure and/or properties by the solvent. For this reason, focused models, that is, strategies paying privileged attention to the solute, seem the methods of choice and several reports suggest that, among different alternatives, QM/MM models are especially effective . Solvent effects on the solute structure and/or properties are tuned by a subtle interplay of short‐ and long‐range contributions.…”

Section: Introductionmentioning

confidence: 99%

Analytical gradients for MP2, double hybrid functionals, and TD‐DFT with polarizable embedding described by fluctuating charges

2015

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A polarizable quantum mechanics (QM)/ molecular mechanics (MM) approach recently developed for Hartree–Fock (HF) and Kohn–Sham (KS) methods has been extended to energies and analytical gradients for MP2, double hybrid functionals, and TD‐DFT models, thus allowing the computation of equilibrium structures for excited electronic states together with more accurate results for ground electronic states. After a detailed presentation of the theoretical background and of some implementation details, a number of test cases are analyzed to show that the polarizable embedding model based on fluctuating charges (FQ) is remarkably more accurate than the corresponding electronic embedding based on a fixed charge (FX) description. In particular, a set of electronegativities and hardnesses has been optimized for interactions between QM and FQ regions together with new repulsion–dispersion parameters. After validation of both the numerical implementation and of the new parameters, absorption electronic spectra have been computed for representative model systems including vibronic effects. The results show remarkable agreement with full QM computations and significant improvement with respect to the corresponding FX results. The last part of the article provides some hints about computation of solvatochromic effects on absorption spectra in aqueous solution as a function of the number of FQ water molecules and on the use of FX external shells to improve the convergence of the results. © 2015 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc.

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Electronic absorption spectra of pyridine and nicotine in aqueous solution with a combined molecular dynamics and polarizable QM/MM approach

et al. 2016

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The electronic absorption spectra of pyridine and nicotine in aqueous solution have been computed using a multistep approach. The computational protocol consists in studying the solute solvation with accurate molecular dynamics simulations, characterizing the hydrogen bond interactions, and calculating electronic transitions for a series of configurations extracted from the molecular dynamics trajectories with a polarizable QM/MM scheme based on the fluctuating charge model. Molecular dynamics simulations and electronic transition calculations have been performed on both pyridine and nicotine. Furthermore, the contributions of solute vibrational effect on electronic absorption spectra have been taken into account in the so called vertical gradient approximation.

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The Electronic Circular Dichroism of Nicotine in Aqueous Solution: A Test Case for Continuum and Mixed Explicit-Continuum Solvation Approaches

Cited by 34 publications

References 70 publications

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

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

Analytical gradients for MP2, double hybrid functionals, and TD‐DFT with polarizable embedding described by fluctuating charges

Electronic absorption spectra of pyridine and nicotine in aqueous solution with a combined molecular dynamics and polarizable QM/MM approach

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