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On the axial chirality of leucoindigo. J Comput Chem 2023; 44:1578-1586. [PMID: 37026434 DOI: 10.1002/jcc.27109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 03/02/2023] [Accepted: 03/14/2023] [Indexed: 04/08/2023]
Abstract
The diagonal components and the trace of two tensors which account for chiroptical response of the leucoindigo molecule C 16 H 12 N 2 O 2 $$ {\mathrm{C}}_{16}{\mathrm{H}}_{12}{\mathrm{N}}_2{\mathrm{O}}_2 $$ that is, static anapole magnetizability, and dynamic electric dipole-magnetic dipole polarisability depending on the frequency of impinging light, are a function of the ϕ $$ \phi $$ dihedral angle of torsion about the central CC bond, assumed to lie in the y $$ y $$ direction of the coordinate system. They vanish for symmetry reasons at ϕ = 0 ∘ $$ \phi ={0}^{\circ } $$ and ϕ = 180 ∘ $$ \phi ={180}^{\circ } $$ , corresponding respectively to C 2 v $$ {C}_{2v} $$ and C 2 h $$ {C}_{2h} $$ point group symmetries, that is, cis and trans conformers characterized by the presence of molecular symmetry planes. Nonetheless, diagonal components and average value of static anapole polarizability and optical rotation tensors vanish at ϕ = 90 ∘ $$ \phi ={90}^{\circ } $$ , where leucondigo is unquestionably chiral from the geometrical viewpoint. Vanishing values of the average chiroptical properties have been observed also in the proximity of other ϕ $$ \phi $$ angles. Attempts have been made to explain the occurrence of accidental zeros of chiroptical properties in terms of transition frequencies and scalar products appearing in the numerator of their quantum mechanical definitions. Within the electric dipole approximation, the presence of anomalous vanishing values of tensor components of anapole magnetizability and electric-magnetic dipole polarizability is ascribed to physical achirality, arising from the lack of either toroidal or spiral electron flow along the x $$ x $$ , y $$ y $$ and z $$ z $$ directions.
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Could Electronic Anapolar Interactions Drive Enantioselective Syntheses in Strongly Nonuniform Magnetic Fields? A Computational Study. J Chem Theory Comput 2019; 15:961-971. [DOI: 10.1021/acs.jctc.8b01002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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3
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Electric Dipole-Magnetic Dipole Polarizability and Anapole Magnetizability of Hydrogen Peroxide as Functions of the HOOH Dihedral Angle. J Phys Chem A 2017; 121:9369-9376. [PMID: 29131953 DOI: 10.1021/acs.jpca.7b09104] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The trace of tensors that account for chiroptical response of the H2O2 molecule is a function of the HO-OH dihedral angle. It vanishes at 0° and 180°, due to the presence of molecular symmetry planes, but also for values in the range 90-100° of this angle, in which the molecule is unquestionably chiral. Such an atypical effect is caused by counterbalancing contributions of diagonal tensor components with nearly maximal magnitude but opposite sign, determined by electron flow in open or closed helical paths, and associated with induced electric and magnetic dipole moments and anapole moments. For values of dihedral angle external to the 90-100° interval, the helical paths become smaller in size, thus reducing the amount of cancellation among diagonal components. Shrinking of helical paths determines the appearance of extremum values of tensor traces approximately at 50° and 140° dihedral angles.
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Theoretical estimates of the anapole magnetizabilities of C4H4X2 cyclic molecules for X=O, S, Se, and Te. J Chem Phys 2014; 141:094305. [DOI: 10.1063/1.4893991] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Magnetizabilities of Diatomic and Linear Triatomic Molecules in a Time-Independent Nonuniform Magnetic Field. J Phys Chem A 2013; 118:6333-42. [DOI: 10.1021/jp408969k] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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6
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Can Induced Orbital Paramagnetism Be Controlled by Strong Magnetic Fields? J Chem Theory Comput 2009; 5:3049-59. [DOI: 10.1021/ct900390s] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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7
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Electric quadrupole polarizabilities of nuclear magnetic shielding in some small molecules. J Chem Phys 2008; 128:044117. [PMID: 18247940 DOI: 10.1063/1.2826342] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Computational procedures, based on (i) the Ramsey common origin approach and (ii) the continuous transformation of the origin of the quantum mechanical current density-diamagnetic zero (CTOCD-DZ), were applied at the Hartree-Fock level to determine electric quadrupole polarizabilities of nuclear magnetic shielding for molecules in the presence of a nonuniform electric field with a uniform gradient. The quadrupole polarizabilities depend on the origin of the coordinate system, but values of the magnetic field induced at a reference nucleus, determined via the CTOCD-DZ approach, are origin independent for any calculations relying on the algebraic approximation, irrespective of size and quality of the (gaugeless) basis set employed. On the other hand, theoretical estimates of the induced magnetic field obtained by single-origin methods are translationally invariant only in the limit of complete basis sets. Calculations of electric quadrupole polarizabilities of nuclear magnetic shielding are reported for H(2), HF, H(2)O, NH(3), and CH(4) molecules.
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Calculation of the electric hypershielding at the nuclei of molecules in a strong magnetic field. J Chem Phys 2007; 126:154103. [PMID: 17461610 DOI: 10.1063/1.2716666] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The third-rank electric hypershielding at the nuclei of 14 small molecules has been evaluated at the Hartree-Fock level of accuracy, by a pointwise procedure for the geometrical derivatives of magnetic susceptibilities and by a straightforward use of its definition within the Rayleigh-Schrodinger perturbation theory. The connection between these two quantities is provided by the Hellmann-Feynman theorem. The magnetically induced hypershielding at the nuclei accounts for distortion of molecular geometry caused by strong magnetic fields and for related changes of magnetic susceptibility. In homonuclear diatomics H(2), N(2), and F(2), a field along the bond direction squeezes the electron cloud toward the center, determining shorter but stronger bond. It is shown that constraints for rotational and translational invariances and hypervirial theorems provide a natural criterion for Hartree-Fock quality of computed nuclear electric hypershielding.
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A third blind test of crystal structure prediction. ACTA CRYSTALLOGRAPHICA SECTION B: STRUCTURAL SCIENCE 2005; 61:511-27. [PMID: 16186652 DOI: 10.1107/s0108768105016563] [Citation(s) in RCA: 241] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2004] [Accepted: 05/24/2005] [Indexed: 11/10/2022]
Abstract
Following the interest generated by two previous blind tests of crystal structure prediction (CSP1999 and CSP2001), a third such collaborative project (CSP2004) was hosted by the Cambridge Crystallographic Data Centre. A range of methodologies used in searching for and ranking the likelihood of predicted crystal structures is represented amongst the 18 participating research groups, although most are based on the global minimization of the lattice energy. Initially the participants were given molecular diagrams of three molecules and asked to submit three predictions for the most likely crystal structure of each. Unlike earlier blind tests, no restriction was placed on the possible space group of the target crystal structures. Furthermore, Z′ = 2 structures were allowed. Part-way through the test, a partial structure report was discovered for one of the molecules, which could no longer be considered a blind test. Hence, a second molecule from the same category (small, rigid with common atom types) was offered to the participants as a replacement. Success rates within the three submitted predictions were lower than in the previous tests – there was only one successful prediction for any of the three `blind' molecules. For the `simplest' rigid molecule, this lack of success is partly due to the observed structure crystallizing with two molecules in the asymmetric unit. As in the 2001 blind test, there was no success in predicting the structure of the flexible molecule. The results highlight the necessity for better energy models, capable of simultaneously describing conformational and packing energies with high accuracy. There is also a need for improvements in search procedures for crystals with more than one independent molecule, as well as for molecules with conformational flexibility. These are necessary requirements for the prediction of possible thermodynamically favoured polymorphs. Which of these are actually realised is also influenced by as yet insufficiently understood processes of nucleation and crystal growth.
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Abstract
Traces of magnetizability, traces of magnetic shielding at the hydrogen nuclei, and nucleus-independent chemical shift are not reliable aromaticity quantifiers for planar conjugated hydrocarbons. A measure of aromaticity is provided by the out-of-plane tensor components, whose magnitude is influenced by the pi-ring currents. The failure of nucleus-independent chemical shift in this regard was proved for the molecule shown in the abstract graphic, sustaining a diatropic pi-current. The validity of the ring-current model is reaffirmed. [structure: see text]
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Ring current effects on nuclear magnetic shielding of carbon in the benzene molecule. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2005; 43:316-320. [PMID: 15625723 DOI: 10.1002/mrc.1536] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The differential Biot-Savart law of classical electrodynamics was applied to develop a ring current model for the magnetic shielding of the carbon nucleus in benzene. It is shown that the local effect of the pi currents, induced by a magnetic field normal to the molecular plane, on the sigmaC out-of-plane shielding tensor component vanishes. However, approximately 10% of sigmaC is due to the shielding contributions from pi current density in the region of the other carbon atoms. Magnetic shielding density maps obtained via quantum mechanical procedures confirm the predictions of the classical model.
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Abstract
The fourth-rank hypermagnetizability tensor of the benzene molecule has been evaluated at the coupled Hartree-Fock level of accuracy within the conventional common-origin approach, adopting gaugeless basis sets of increasing size and flexibility. The degree of convergence of theoretical tensor components has been estimated allowing for two different coordinate systems. It is shown that a strong magnetic field perpendicular to the plane of the molecule causes a distortion of the electron charge density, which tends to concentrate in the region of the C-C bonds. This charge contraction has a dynamical origin, and can be interpreted as a feedback effect in terms of the classical Lorentz force acting on the electron current density.
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Modeling solid-state effects on NMR chemical shifts using electrostatic models. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2004; 42 Spec no:S41-S47. [PMID: 15366040 DOI: 10.1002/mrc.1432] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
This paper presents a comparison of the embedded ion method (EIM) and the surface charge representation of the electrostatic embedding potential (SCREEP) method, two methods which can be used to calculate solid-state effects on NMR chemical shifts. The results in a selected group of compounds with known single-crystal solid-state NMR data and neutron diffraction structures, confirm that these effects are important in both (13)C and (15)N chemical shifts. The solid-state effects calculated by both methods are similar and of equal statistical quality when compared with the experimental data.
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Calculation of the fourth-rank molecular hypermagnetizability of some small molecules. J Chem Phys 2004; 120:9556-60. [PMID: 15267967 DOI: 10.1063/1.1695551] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A computational scheme has been developed within the framework of Rayleigh-Schrödinger perturbation theory to evaluate nonlinear interaction energy contributions for a molecule in the presence of an external spatially uniform, time-independent magnetic field. Terms connected with the fourth power of the perturbing field, representing the fourth-rank hypermagnetizabilities of five small molecules, have been evaluated at the coupled Hartree-Fock level of accuracy within the conventional common-origin approach. Gaugeless basis sets of increasing size and flexibility have been employed in a numerical test, adopting two different coordinate systems to estimate the degree of convergence of theoretical tensor components.
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On the resolution of the optical rotatory power of chiral molecules into atomic terms. A study of hydrogen peroxide. J Chem Phys 2002. [DOI: 10.1063/1.1461816] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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16
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Resolution of molecular polarizabilities of CH3–X and CH3–CH2–X derivatives into atomic terms. J Chem Phys 2001. [DOI: 10.1063/1.1343902] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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17
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Solid-State nuclear magnetic resonance: performance of point-charge distributions to model intermolecular effects in 19 F chemical shifts. Theor Chem Acc 2000. [DOI: 10.1007/s002140000145] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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18
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Shielding polarizabilities via continuous transformation of the origin of the current density in the set of small molecules: H2O2, F2, H2C2, H2CO, NH3, HCN, and HNC. J Chem Phys 2000. [DOI: 10.1063/1.481215] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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19
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Ab initio calculation of atomic contributions to the magnetic susceptibility by continuous transformation of the origin of the current density in HF, H2O, NH3, and CH4 molecules. J Chem Phys 1999. [DOI: 10.1063/1.478040] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Modeling NMR chemical shifts: a comparison of charge models for solid state effects on 15N chemical shift tensors. SOLID STATE NUCLEAR MAGNETIC RESONANCE 1998; 10:185-189. [PMID: 9603618 DOI: 10.1016/s0926-2040(97)00086-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
This paper presents results from applying different point charge models to take into account intermolecular interactions to model the solid state effects on the 15N NMR chemical shifts tensors. The DFT approach with the BLYP gradient corrected exchange correlation functional has been used because it can include electron correlation effects at a reasonable cost and is able to reproduce 15N NMR chemical shifts with reasonable accuracy. The results obtained with the point charge models are compared with the experimental data and with results obtained using the cluster model, which includes explicitly neighboring molecular fragments. The results show that the point charge models can take into account solid state effects at a cost much lower than the cluster methods.
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22
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Theoretical study of magnetic properties of ammonia molecule in nonuniform magnetic field. ACTA ACUST UNITED AC 1996. [DOI: 10.1007/bf00191646] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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23
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Conditions for invariance of molecular magnetic properties in Landau gauge transformations. J Chem Phys 1995. [DOI: 10.1063/1.469709] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Theoretical study of the magnetic properties of a methane molecule in a nonuniform magnetic field. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1994; 49:3445-3449. [PMID: 9910642 DOI: 10.1103/physreva.49.3445] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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25
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Calculation of molecular magnetic properties within the Landau gauge in hydrogen fluoride, ammonia, and methane molecules. J Chem Phys 1993. [DOI: 10.1063/1.464033] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Calculation of molecular magnetic properties within the Landau gauge. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1992; 45:6272-6281. [PMID: 9907748 DOI: 10.1103/physreva.45.6272] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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