Special Issue "Polar and Centrosymmetric Packings in Molecular Crystals"

A special issue of Crystals (ISSN 2073-4352).

Deadline for manuscript submissions: closed (31 August 2017)

Special Issue Editor

Prof. Dr. Roberto Centore
E-Mail Website
Guest Editor
University of Naples Federico II, Department of Chemical Sciences, ViaCintia, I-80126 Naples, Italy
Interests: advanced materials: synthesis of molecules and polymers for applications in the fields of liquid-crystals, organic electronics, optoelectronics and photovoltaics; crystal engineering: crystal structures driven by the formation of H bonds, acentric and polar crystals, polymorphism and topotactic transitions, mechanically responsive dynamic crystals, solid-state separation of tautomers

Special Issue Information

Dear Colleagues,

In a polar crystal there is a direction that is not transformed in the opposite direction by any symmetry operation of the crystal class. That direction is called the polar axis of the crystal. There is a general interest in polar crystals, because some physical properties of materials, highly desired for advanced applications, such as pyroelectricity, piezoelectricity, ferroelectricity, second harmonic generation, and electrooptic effect, are only allowed, or they are strongly enhanced, in polar space groups. On the other hand, the center of symmetry transforms each direction in the opposite one, so that centrosymmetric crystals are not polar. It is well known to any crystallographer that a large fraction of organic non-chiral compounds crystallize in centrosymmetric space groups, mainly P21/c and P\(\bar{1}\). Actually, the bias for centrosymmetric over acentric crystals is a problem lying at the very heart of crystallography, addressed since the beginning of the discipline. It is still a long debated, challenging problem of the structural science.

We invite investigators to submit papers that, in a broad sense, can help to find the conditions that favor the formation of acentric and polar molecular crystals, over centrosymmetric crystals. The conditions can be met by crystal engineering techniques or by crystal growth techniques in the case of compounds exhibiting both a polar and a centrosymmetric polymorph.

The potential topics include, but are not limited to:

  • Description of new polar and/or acentric crystals from non chiral compounds
  • Physical properties of new acentric and/or polar crystals
  • Compounds showing polymorphism with a centrosymmetric and a noncentrosymmetric phase
  • Phase transitions between polar polymorphs and between polar and centrosymmetric polymorphs
  • Database screening of compounds forming acentric and/or polar crystal structures

Prof. Roberto Centore
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Crystals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.


  • Polar crystals
  • Acentric crystals
  • Physical properties of crystals
  • Polymorphism
  • Phase transitions in crystals
  • Crystal engineering

Published Papers (1 paper)

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Synthesis, Crystal Structure, Spectroscopic Properties, and DFT Studies of 7,9-Dibromobenzo[h]quinolin-10-ol
Crystals 2017, 7(2), 60; https://doi.org/10.3390/cryst7020060 - 21 Feb 2017
Viewed by 2450
7,9-Dibromobenzo[h]quinolin-10-ol (1), a benzo[h]quinolin-10-ol derivative, was synthesized and characterized by single-crystal X-ray diffraction. The crystal belongs to monoclinic space group P21/n, with a = 3.9573(4), b = 18.0416(18), c = 15.8210(16) Å, [...] Read more.
7,9-Dibromobenzo[h]quinolin-10-ol (1), a benzo[h]quinolin-10-ol derivative, was synthesized and characterized by single-crystal X-ray diffraction. The crystal belongs to monoclinic space group P21/n, with a = 3.9573(4), b = 18.0416(18), c = 15.8210(16) Å, α = 90°, β = 96.139(3)°, and γ = 90°. Compound 1 exhibits an intramolecular six-membered-ring hydrogen bond, from which excited-state intramolecular proton transfer takes place, resulting in a proton-transfer tautomer emission of 625 nm in cyclohexane. The crystal structure is stabilized by intermolecular π–π interactions, which links a pair of molecules into a cyclic centrosymmetric dimer. Furthermore, the geometric structures, frontier molecular orbitals, and potential energy curves (PECs) for 1 in the ground and the first singlet excited state were fully rationalized by density functional theory (DFT) and time-dependent DFT calculations. Full article
(This article belongs to the Special Issue Polar and Centrosymmetric Packings in Molecular Crystals)
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