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Electron Density of Two Bioactive Oligocyclic Indole and Oxindole Derivatives Obtained from Low-Order X-Ray Data and Invariom Application

Authors

  • Manuela Weber,

    1. Freie Universität Berlin, Institut für Chemie und Biochemie- Anorganische Chemie, Fabeckstraße 36a, 14195 Berlin (Germany), Fax: (+49) 30-8385-3464
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  • Dr. Simon Grabowsky,

    1. Freie Universität Berlin, Institut für Chemie und Biochemie- Anorganische Chemie, Fabeckstraße 36a, 14195 Berlin (Germany), Fax: (+49) 30-8385-3464
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  • Dr. Abhijit Hazra,

    1. Department of Chemistry, Council of Scientific and Industrial Research, Indian Institute of Chemical Biology, Jadavpur, Kolkata 700032 (India)
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  • Subhendu Naskar,

    1. Department of Chemistry, Council of Scientific and Industrial Research, Indian Institute of Chemical Biology, Jadavpur, Kolkata 700032 (India)
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  • Dr. Sukdeb Banerjee,

    1. Department of Chemistry, Council of Scientific and Industrial Research, Indian Institute of Chemical Biology, Jadavpur, Kolkata 700032 (India)
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  • Dr. Nirup B. Mondal,

    1. Department of Chemistry, Council of Scientific and Industrial Research, Indian Institute of Chemical Biology, Jadavpur, Kolkata 700032 (India)
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  • Prof. Peter Luger

    Corresponding author
    1. Freie Universität Berlin, Institut für Chemie und Biochemie- Anorganische Chemie, Fabeckstraße 36a, 14195 Berlin (Germany), Fax: (+49) 30-8385-3464
    • Freie Universität Berlin, Institut für Chemie und Biochemie- Anorganische Chemie, Fabeckstraße 36a, 14195 Berlin (Germany), Fax: (+49) 30-8385-3464

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Abstract

For two indole and oxindole bioactive molecules, low-order room-temperature X-ray data were used to generate aspherical electron density (ED) distributions by application of the invariom formalism. An analysis of the ED using the quantum theory of atoms in molecules (QTAIM) was carried out, which allowed for quantitatively examining bond orders and charge separations in various parts of the molecules. The inspection of electrostatic potentials (ESPs) and Hirshfeld surfaces provided additional information on the intermolecular interactions. Thus, reactive regions of the molecules could be identified, covalent and electrostatic contributions to interactions could be visualized, and the forces causing the crystal packing scheme could be rationalized. As the used invariom formalism needs no extra experimental effort compared to routine X-ray analysis, its wide application is recommended because it delivers information far beyond the normally obtained steric properties. In this way, complementary contributions to drug design can be given as is demonstrated for indoles in this study, which are involved in the metabolism of plants and animals as well as in cancer therapy.

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