International Journal of Quantum Chemistry

Cover image for Vol. 113 Issue 22

15 November 2013

Volume 113, Issue 22

Pages i–iv, 2413–2488

  1. Cover Image

    1. Top of page
    2. Cover Image
    3. Review
    4. Full Papers
    1. You have free access to this content
      Cover Image, Volume 113, Issue 22 (pages i–ii)

      Article first published online: 7 OCT 2013 | DOI: 10.1002/qua.24554

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      Modern semi-empirical molecular orbital methods are applied to direct calculation of optical rotatory strengths by Masashi Hatanaka on page 2447. The octant rule for asymmetric ketones is well reproduced under the reoptimized Hamiltonians, and is reasonably related to the charge-transfer perturbations of the substituents. The up-to-date methods well reproduce circular dichroism/optical rotatory dispersion spectra of a typical helicene with complete active space configuration interactions. The applicability to biopolymers is also evaluated using fundamental polypeptides as targets. The results indicate that these methods may serve as practical predictors of chiroptical properties.

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      Inside Cover, Volume 113, Issue 22 (pages iii–iv)

      Article first published online: 7 OCT 2013 | DOI: 10.1002/qua.24555

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      Quantum chemical calculations on the reactivity of different carbon bases reveal that although both carbon(II) and carbon(0) bases show similar reactivity towards electrophiles, they show distinctive reactivity towards nucleophiles. Carbon(II) bases, being ambiphilic in nature, react easily with nucleophiles while it is not so facile for carbon(0) bases. The presence of a suitable low-lying p-accepting orbital in carbon(II) bases, a key electronic feature, is responsible for such a reactivity difference, as presented by Ankur Kanti Guha, Ujjal Gogoi, and Ashwini K. Phukan on page 2471.

  2. Review

    1. Top of page
    2. Cover Image
    3. Review
    4. Full Papers
    1. You have free access to this content
      Milestones in graphical bioinformatics (pages 2413–2446)

      Milan Randić, Marjana Novič and Dejan Plavšić

      Article first published online: 7 JUN 2013 | DOI: 10.1002/qua.24479

      Thumbnail image of graphical abstract

      Graphical representations of DNA, RNA, and protein sequences can be characterized numerically based on mathematical invariants extracted from graphical representations. The image shows one novel graphical representation of a map. In contrast to standard bioinformatics, graphical bioinformatics can be used to study single DNA strands. This review examines the seminal developments in this field over the past several decades, in a conversational style.

  3. Full Papers

    1. Top of page
    2. Cover Image
    3. Review
    4. Full Papers
    1. Evaluation of optical activities by modern semi-empirical methods (pages 2447–2456)

      Masashi Hatanaka

      Article first published online: 11 JUN 2013 | DOI: 10.1002/qua.24478

      Thumbnail image of graphical abstract

      Modern semi-empirical molecular orbital methods are applied to direct calculation of optical rotatory strengths. The octant rule for asymmetric ketones is reasonably related to the charge-transfer perturbations of the substituents. The up-to-date methods well reproduce circular dichroism/optical rotatory dispersion spectra of a typical helicene with configuration interactions. The applicability to biopolymers is also evaluated using fundamental polypeptides as targets. The results indicate that these methods may serve as practical predictors of chiroptical properties.

    2. Theoretical study on the mechanism of the reaction for alkene hydroaminations catalyzed by chiral aldehyde (pages 2457–2463)

      Jinfeng Zhao, Chuanzhi Sun, Nan Sun, Lin Meng and Dezhan Chen

      Article first published online: 4 JUN 2013 | DOI: 10.1002/qua.24483

      Thumbnail image of graphical abstract

      Alkene hydroamination catalyzed by chiral aldehyde, based on temporary intramolecularity, is a new concept in chemistry. To clarify the reaction mechanism, alkene hydroamination of N-benzylhydroxylamine and secondary allylic amine is modeled using DFT. The chiral catalyst allows the key formation of a mixed aminal species, resulting in a facile intramolecular hydroamination event. Simple aldehyde precatalyst enables the synthesis of vicinal diamines through temporary intramolecularity.

    3. Theoretical study of electronic structure of rhodium mononitride and interpretation of experimental spectra (pages 2464–2470)

      Ranran Du, Bingbing Suo, Huixian Han, Yibo Lei and Gaohong Zhai

      Article first published online: 5 JUN 2013 | DOI: 10.1002/qua.24484

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      Ab initio calculations play an important role in interpretation of the molecular spectra. In this work, potential energy curves of 22 electronic states of the rhodium nitride (RhN) molecule are calculated, accounting for scalar relativistic effect and spin-orbit coupling. Available experimental spectra of RhN are interpreted and assigned according to the theoretical results obtained. This work is expected to provide a usable reference for studies of this transition metal nitride.

    4. Revisiting the reactivity of different carbon bases: A theoretical study (pages 2471–2477)

      Ankur Kanti Guha, Ujjal Gogoi and Ashwini K. Phukan

      Article first published online: 11 JUN 2013 | DOI: 10.1002/qua.24485

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      Quantum chemical calculations reveal that the distinction between carbon(II) and carbon(0) bases becomes blurred with the increase in π-donation abilities of carbon(II) bases. Moderate to strong π-accepting ability is a key electronic feature that may distinguish a carbene from carbone. This is reflected in the activation barrier for the addition of a nucleophile to either carbon(II) or carbon(0) base.

    5. Deflation techniques in quantum chemistry: Excited states from ground states (pages 2478–2488)

      Ramón Alain Miranda-Quintana and Marco Martínez González

      Article first published online: 12 JUN 2013 | DOI: 10.1002/qua.24486

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      Understanding the properties of the excited states of molecular systems is of paramount importance in different fields (e.g., design of photovoltaic devices). However, studying excited states is a challenge greater than studying ground states. This work shows how ground state theoretical techniques can be used to tackle excited state problems. This simplifies the study of excited states, opening a wide range of techniques to analyze them.

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