Electronic absorption, polarised excitation, and circular dichroism spectra of [5]-helicene (dibenzo[c,g]phenanthrene)

Brown, AP; Kemp, Colin M.; Mason, S. F.

doi:10.1039/j19710000751

Cited by 83 publications

(108 citation statements)

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“…The rotational strength R is thus equal to the imaginary part of the scalar product of electric and magnetic transition moments. The rotational strength R is calculable by theories suitable for each chiral compound; for example, the exciton theory for exciton-coupled compounds, 22,25,26 the p-electron SCF-CI-DV MO method for compounds with twisted p-electron systems, 21,27,28 the semiempirical CNDO/S calculation for some chiral aromatics and hetero compounds, 29 and the ab initio MO method of TDDFT calculation for most chiral compounds [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] have been employed. If the ECD Cotton effect is approximated by the Gaussian distribution, the CD curve is formulated as:…”

Section: Introductionmentioning

confidence: 99%

ECD cotton effect approximated by the Gaussian curve and other methods

2009

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To determine the absolute configuration of chiral compounds, theoretical calculations of ECD spectra have been extensively carried out, where the shape of component CD Cotton effects was approximated by the Gaussian distribution curve. However, in some articles, errors are found in the equations of Gaussian curve expressing CD Cotton effects. In this short review, the correct and general forms of the Gaussian equation and the approximation of the CD curve by other methods are described.

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Section: Introductionmentioning

confidence: 99%

ECD cotton effect approximated by the Gaussian curve and other methods

2009

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“…A related study of helicenes was previously published by Grimme et al 64 based on an approximation to TD-DFT. Pioneering experimental and theoretical work has been carried out by Mason et al 53,54 We do not attempt to repeat the detailed discussion of the spectra and the analysis of Ref. 12, and earlier work, here.…”

Section: E Helicenesmentioning

confidence: 99%

Chiroptical properties from time-dependent density functional theory. I. Circular dichroism spectra of organic molecules

Autschbach

Ziegler

Gisbergen³

et al. 2002

The Journal of Chemical Physics

413

330

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We report the implementation of the computation of rotatory strengths, based on time-dependent density functional theory, within the Amsterdam Density Functional program. The code is applied to the simulation of circular dichroism spectra of small and moderately sized organic molecules, such as oxiranes, aziridines, cyclohexanone derivatives, and helicenes. Results agree favorably with experimental data, and with theoretical results for molecules that have been previously investigated by other authors. The efficient algorithms allow for the simulation of CD spectra of rather large molecules at a reasonable accuracy based on first-principles theory. The choice of the Kohn-Sham potential is a critical issue. It is found that standard gradient corrected functionals often yield the correct shape of the spectrum, but the computed excitation energies are systematically underestimated for the samples being studied. The recently developed exchange-correlation potentials ''GRAC'' and ''SAOP'' often yield much better agreement here with experiments for the excitation energies. The rotatory strengths of individual transitions are usually improved by these potentials as well.

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“…The spectral curves were generated using a sum of Lorentzian curves, each of which was centred at the corresponding transition wavelength and multiplied with the associated oscillator strength. The halfbandwidth G was calculated using the empirical formula G ¼ kl 1.5 [25] with k ¼ 0.00375 (R. W. Woody, pers. comm.…”

Section: Methodsmentioning

confidence: 99%

Corrigendum to: Quantum-chemical Ab Initio Calculations on the Donor–Acceptor Complex Pyridine–Borabenzene (C5H5N–BC5H5)

Mbarki¹,

Oettinghaus²,

Raabe³

2016

Aust. J. Chem.

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The adduct of borabenzene (C 5 H 5 B) and pyridine (C 5 H 5 N) was studied by means of quantum-chemical ab initio and timedependent density functional theory calculations at different levels of theory. In the fully optimized structure (MP2/ 6-311þþG**) of the free donor-acceptor complex (C 2 ), the C-B-C angle amounts to 120.68. The planes of the two aromatic rings enclose a torsion angle of ,408 with a barrier to rotation about the B-N bond of less than 3 kcal mol À1 (1 kcal mol À1 ¼ 4.186 kJ mol À1 ). The highest computational level applied in this study (complete basis set limit, coupled cluster with single and double excitations (CCSD)) results in an energy associated with the reaction of borabenzene with pyridine of À52.2 kcal mol À1 . Natural bond orbital analyses were performed to study the bond between the borabenzene and the pyridine unit of the adduct. The UV-vis spectrum of the adduct was calculated employing time-dependent density functional theory methods and the symmetry-adapted cluster-configuration interaction method. Our calculated electronic excitation spectrum of the pyridine adduct as well as its spectrum of the normal modes qualitatively reproduce the characteristic features of the IR and the UV-vis spectra described by experimentalists and thus allows assignment of the observed absorption bands, which in part agree with those by other authors.

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Electronic absorption, polarised excitation, and circular dichroism spectra of [5]-helicene (dibenzo[c,g]phenanthrene)

Cited by 83 publications

References 0 publications

ECD cotton effect approximated by the Gaussian curve and other methods

ECD cotton effect approximated by the Gaussian curve and other methods

Chiroptical properties from time-dependent density functional theory. I. Circular dichroism spectra of organic molecules

Corrigendum to: Quantum-chemical Ab Initio Calculations on the Donor–Acceptor Complex Pyridine–Borabenzene (C5H5N–BC5H5)

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