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Andersen JH, Hättig C, Coriani S, Štěpánek P. Insights into localization, energy ordering, and substituent effect in excited states of azobenzenes from coupled cluster calculations of nuclear spin-induced circular dichroism. Phys Chem Chem Phys 2024; 26:9179-9196. [PMID: 37921593 DOI: 10.1039/d3cp02547k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2023]
Abstract
Nuclear spin-induced circular dichroism (NSCD) is a molecular effect of differential absorption of left- and right-circularly polarized light due to nuclear spins in the molecule. In this work, new tools for its calculation are presented. Specifically, analytic expressions for the computation of the K term of NSCD have been derived and implemented for the second-order coupled cluster singles and doubles (CC2) model. NSCD results obtained thereby for three derivatives of azobenzenes have been compared with results from time-dependent density functional theory (TD-DFT). The complementary information that could be obtained from NSCD measurements compared to NMR for these three species is discussed.
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Affiliation(s)
- Josefine H Andersen
- DTU Chemistry, Technical University of Denmark, Kemitorvet Building 207, DK-2800 Kongens Lyngby, Denmark.
| | - Christof Hättig
- Arbeitsgruppe Quantenchemie, Ruhr-Universität Bochum, D-44780 Bochum, Germany
| | - Sonia Coriani
- DTU Chemistry, Technical University of Denmark, Kemitorvet Building 207, DK-2800 Kongens Lyngby, Denmark.
| | - Petr Štěpánek
- NMR Research Unit, Faculty of Science, University of Oulu, PO Box 3000, FI-90014 Oulu, Finland.
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Kamula E, Vaara J, Štěpánek P. Characteristic nuclear spin-induced optical rotation in oxygen-containing organic molecules. Phys Chem Chem Phys 2023; 25:27731-27743. [PMID: 37814529 DOI: 10.1039/d3cp02352d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/11/2023]
Abstract
Nuclear spin-induced optical rotation (NSOR) is a nuclear magneto-optic effect that manifests itself as a rotation of the plane of polarization of linearly polarized light. The effect is induced by ordered nuclear magnetic moments within a molecule. NSOR is sensitive to specific, localized interactions. Hence, the connection between the local chemical environment and the corresponding NSOR signal is crucial to understand. Despite the fact that contributions to better understand the connection have been made, the general systematics still remain unknown. In this paper, NSOR in oxygen compounds is investigated systematically to better understand the impact of oxygen atoms on the NSOR signal. NSOR signals are computed using density-functional theory methods for five different classes of oxygen compounds. The ability of NSOR to distinguish different molecules and individual nuclei in the molecules is studied and the information provided by NSOR is compared to conventional NMR spectroscopy. The results reveal that NSOR is capable of chemical distinction between nuclei and molecules, and by using NMR and NSOR together it is possible to distinguish nuclei near the oxygen atom.
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Affiliation(s)
- Eelis Kamula
- NMR Research Unit, Faculty of Science, University of Oulu, Oulu, FI-90014, Finland.
| | - Juha Vaara
- NMR Research Unit, Faculty of Science, University of Oulu, Oulu, FI-90014, Finland.
| | - Petr Štěpánek
- NMR Research Unit, Faculty of Science, University of Oulu, Oulu, FI-90014, Finland.
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Štěpánek P. Nuclear spin-induced optical rotation of functional groups in hydrocarbons. Phys Chem Chem Phys 2020; 22:22195-22206. [PMID: 32776074 DOI: 10.1039/d0cp02856h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Nuclear spin-induced optical rotation (NSOR) is a nuclear magneto-optic effect manifesting as a rotation of the plane of polarization of linearly polarized light induced by nuclear magnetic moments within a molecule. NSOR probes molecular optical properties through localized nuclear interactions and has potential to be developed into a new spectroscopic tool. However, so far the connection between the molecular structure and NSOR response has not been systematically investigated. To obtain insight into this relation and to assess its viability as a foundation for a new spectroscopic method, NSOR of 1H and 13C nuclei in a set of hydrocarbon molecules with various structural motifs is theoretically investigated using density functional theory calculations. The results reveal that NSOR intensities are correlated with several structural features of the molecules, such as the position of the nucleus in the carbon chain, isomerism and presence of nearby unsaturated groups. Specific patterns connecting NSOR to the local chemical environment of the nucleus can be observed. It is also shown that this effect can be to a good approximation modelled as a sum of individual contributions from nearby chemical groups, allowing for a rapid estimation of its values. The demonstrated systematic dependence of the NSOR signal on the molecular structure is a desirable feature for theoretical and experimental development of new spectroscopic methods based on this phenomenon.
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Affiliation(s)
- Petr Štěpánek
- NMR Research Unit, Faculty of Science, University of Oulu, P.O. Box 3000, FI-90014, Oulu, Finland.
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Štěpánek P, Kantola AM. Low-Concentration Measurements of Nuclear Spin-Induced Optical Rotation Using SABRE Hyperpolarization. J Phys Chem Lett 2019; 10:5458-5462. [PMID: 31454246 PMCID: PMC7076727 DOI: 10.1021/acs.jpclett.9b02194] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 08/27/2019] [Indexed: 06/10/2023]
Abstract
Nuclear spin-induced optical rotation (NSOR) is a promising phenomenon for molecular structure elucidation due to its sensitivity to electronic structure near atomic nuclei. It is the only experimentally verified nuclear magneto-optic effect (NMOE), so far observed usually in neat liquids or in concentrated binary mixtures, with the proportion of the minor component at least 10%. We report a method to extend the lower-concentration range of NSOR measurements by 2 orders of magnitude by employing continuous-flow SABRE (signal amplification by reversible exchange) hyperpolarization. This approach significantly increases the sensitivity of NSOR and enables its detection in dilute samples, as demonstrated with measurements of NSOR of 90 mmol/L solutions of pyridine and pyrazine. The results are compared with first-principles calculations, and good agreement is found. The possibility to measure low-concentration solutions significantly extends the pool of samples available for further studies of NMOEs.
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Štěpánek P, Coriani S. Spatial localization in nuclear spin-induced circular dichroism - a quadratic response function analysis. Phys Chem Chem Phys 2019; 21:18082-18091. [PMID: 31145406 DOI: 10.1039/c9cp01716j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Nuclear magneto-optic (NMO) effects are recently described phenomena originating from the interaction of light with local magnetic fields produced by nuclear spins. The phenomena border nuclear magnetic resonance and optical spectroscopy and are expected to provide rather unique spectroscopic features, borrowing from both localized response of the atomic nuclei as well as more global excitation properties of the whole molecule or its chromophore moieties. A number of quantum-chemical computational studies have been carried out, offering a reasonable agreement with nuclear magneto-optics experiments performed so far. However, the detailed structure-spectra relation is still poorly understood. In this report we address the question of locality of one of the NMO effects, namely nuclear spin-induced circular dichroism (NSCD). We implement an alternative computational approach for calculation of the NSCD intensities, based on residues of quadratic response functions, and use it to investigate the NSCD response of different nuclei in a model molecular system with well-defined separate chromophores. The results show that significant NSCD at a given energy only occurs at the nuclei which are located in the chromophore that is excited. We rationalize these findings using analysis via difference densities, and approximate sum-over-states calculations. This behaviour of NSCD opens a way to experimental studies of localization of excited states in molecules, potentially with resolution down to the order of bond-length.
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Affiliation(s)
- Petr Štěpánek
- NMR Research Unit, Faculty of Science, University of Oulu, PO Box 3000, FI-90014 Oulu, Finland.
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Relation between molecular electronic structure and nuclear spin-induced circular dichroism. Sci Rep 2017; 7:46617. [PMID: 28436463 PMCID: PMC5402291 DOI: 10.1038/srep46617] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 03/21/2017] [Indexed: 11/16/2022] Open
Abstract
The recently theoretically described nuclear spin-induced circular dichroism (NSCD) is a promising method for the optical detection of nuclear magnetization. NSCD involves both optical excitations of the molecule and hyperfine interactions and, thus, it offers a means to realize a spectroscopy with spatially localized, high-resolution information. To survey the factors relating the molecular and electronic structure to the NSCD signal, we theoretically investigate NSCD of twenty structures of the four most common nucleic acid bases (adenine, guanine, thymine, cytosine). The NSCD signal correlates with the spatial distribution of the excited states and couplings between them, reflecting changes in molecular structure and conformation. This constitutes a marked difference to the nuclear magnetic resonance (NMR) chemical shift, which only reflects the local molecular structure in the ground electronic state. The calculated NSCD spectra are rationalized by means of changes in the electronic density and by a sum-over-states approach, which allows to identify the contributions of the individual excited states. Two separate contributions to NSCD are identified and their physical origins and relative magnitudes are discussed. The results underline NSCD spectroscopy as a plausible tool with a power for the identification of not only different molecules, but their specific structures as well.
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Chen F, Yao GH, Zhang ZL, Liu FC, Chen DM. Nuclear-Spin-Induced Circular Dichroism in the Infrared Region for Liquids. Chemphyschem 2015; 16:1954-9. [PMID: 25827496 DOI: 10.1002/cphc.201500129] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Indexed: 11/11/2022]
Abstract
Recently, the nuclear-spin-induced optical rotation (NSOR) and circular dichroism (NSCD) for liquids were discovered and extensively studied and developed. However, so far, nuclear-spin-induced magnetic circular dichroism in the IR region (IR-NSCD) has not been explored, even though all polyatomic molecules exhibit extensive IR spectra. Herein, IR-NSCD is proposed and discussed theoretically. The results indicate that in favorable conditions the IR-NSCD angle may be much larger than the NSOR angle in the UV/Vis region due to a vibrational resonance effect and can be measurable by using the NSOR experiment scheme. IR-NSCD can automatically combine and give NMR spectra and IRCD spectra of the nuclear spin prepolarized samples in liquids, which, in principle, could be developed to become a unique, novel analytical tool.
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Affiliation(s)
- Fang Chen
- Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026 (P.R. China)
| | - Guo-hua Yao
- Key Laboratory of Ion Beam Bio-engineering, Institute of Technical Biology and Agriculture Engineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (P.R. China)
| | - Zhen-lin Zhang
- Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026 (P.R. China)
| | - Fan-chen Liu
- Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026 (P.R. China)
| | - Dong-ming Chen
- Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026 (P.R. China).
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Fu LJ, Vaara J. Nuclear-spin-induced cotton-mouton effect in a strong external magnetic field. Chemphyschem 2014; 15:2337-50. [PMID: 24862946 DOI: 10.1002/cphc.201402121] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Indexed: 11/11/2022]
Abstract
Novel, high-sensitivity and high-resolution spectroscopic methods can provide site-specific nuclear information by exploiting nuclear magneto-optic properties. We present a first-principles electronic structure formulation of the recently proposed nuclear-spin-induced Cotton-Mouton effect in a strong external magnetic field (NSCM-B). In NSCM-B, ellipticity is induced in a linearly polarized light beam, which can be attributed to both the dependence of the symmetric dynamic polarizability on the external magnetic field and the nuclear magnetic moment, as well as the temperature-dependent partial alignment of the molecules due to the magnetic fields. Quantum-chemical calculations of NSCM-B were conducted for a series of molecular liquids. The overall order of magnitude of the induced ellipticities is predicted to be 10(-11) -10(-6) rad T(-1) M(-1) cm(-1) for fully spin-polarized nuclei. In particular, liquid-state heavy-atom systems should be promising for experiments in the Voigt setup.
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Affiliation(s)
- Li-Juan Fu
- NMR Research Group, Department of Physics, University of Oulu, P.O. Box 3000, FIN-90014 Oulu (Finland), Fax: (+358) (0)8-553 1287..
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Vaara J, Rizzo A, Kauczor J, Norman P, Coriani S. Nuclear spin circular dichroism. J Chem Phys 2014; 140:134103. [DOI: 10.1063/1.4869849] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
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Fu LJ, Vaara J. Nuclear quadrupole moment-induced Cotton-Mouton effect in molecules. J Chem Phys 2014; 140:024103. [PMID: 24437861 DOI: 10.1063/1.4855315] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Li-juan Fu
- NMR Research Group, Department of Physics, University of Oulu, P.O. Box 3000, FIN-90014 Oulu, Finland
| | - Juha Vaara
- NMR Research Group, Department of Physics, University of Oulu, P.O. Box 3000, FIN-90014 Oulu, Finland
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Straka M, Štěpánek P, Coriani S, Vaara J. Nuclear spin circular dichroism in fullerenes: a computational study. Chem Commun (Camb) 2014; 50:15228-31. [PMID: 25341745 DOI: 10.1039/c4cc07271e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Chemically different carbons in C70 give distinct signals in nuclear spin circular dichroism spectroscopy, a novel candidate for high-resolution identification of chemical compounds.
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Affiliation(s)
- Michal Straka
- Institute of Organic Chemistry and Biochemistry
- Academy of Sciences of the Czech Republic
- Praha 6, Czech Republic
| | - Petr Štěpánek
- Institute of Organic Chemistry and Biochemistry
- Academy of Sciences of the Czech Republic
- Praha 6, Czech Republic
| | - Sonia Coriani
- Dipartimento di Scienze Chimiche e Farmaceutiche
- Università degli Studi di Trieste
- I-34127 Trieste, Italy
| | - Juha Vaara
- NMR Research Group
- Department of Physics and Chemistry
- , Finland
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