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Special Issue "X-ray Crystallography Based Study on Molecular Structure"

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Molecular Structure".

Deadline for manuscript submissions: 15 December 2022 | Viewed by 450

Special Issue Editor

Dr. Kam-Hung Low
E-Mail Website
Guest Editor
X-ray Crystallography Laboratory, Department of Chemistry, University of Hong Kong, Hong Kong, China
Interests: crystal structure determination; single-crystal diffraction; powder diffraction; pharmaceutical cocrystals; functional materials

Special Issue Information

Dear Colleagues,

The discovery of X-ray crystallography a century ago by Sirs William and Lawrence Bragg began a flourishing era of studies on molecular structures. The three-dimensional structure of molecules holds an essential key to understanding and, in some particular cases, predicting their chemical and physical properties, which is the foundation of diverse research fields in modern science, including drug discovery, materials design, structural biology, and quantum mechanics. Accurate atom connectivity with high bond precision (generally better than 0.01 Angstrom) can be achieved in contemporary chemical single-crystal X-ray diffractometers conveniently. X-ray crystallography is advantageous over other structure determination methods, such as cryogenic electron microscopy, in terms of simple sample preparation, user-friendly instrument setup, and low operating expense.

This Special Issue aims to present an overview of the most recent advances in applying X-ray crystallography to a molecular structure. Contributions, including original research manuscripts and reviews, which reveal the studies involving molecular structure determination by X-ray crystallography, are welcome. Studies concerning biologically active small molecules, novel functional materials, and crystallographic data analysis by machine learning will be particularly appreciated.

Dr. Kam-Hung Low
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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. Molecules is an international peer-reviewed open access semimonthly 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 2300 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.

Keywords

  • crystal structure determination
  • single crystal diffraction
  • powder diffraction
  • non-ambient conditions
  • charge density
  • structure prediction
  • non-covalent frameworks
  • absolute structure and configuration
  • drug design
  • computational crystallography

Published Papers (1 paper)

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Research

Article
The First Noncovalent-Bonded Supramolecular Frameworks of (Benzylthio)Acetic Acid with Proline Compounds, Isonicotinamide and Tryptamine
Molecules 2022, 27(23), 8203; https://doi.org/10.3390/molecules27238203 - 24 Nov 2022
Viewed by 220
Abstract
The co-crystallization of (benzylthio)acetic acid (HBTA) with L-proline (L-PRO), D-proline (D-PRO), DL-proline (DL-PRO), isonicotinamide (INA) and tryptamine (TPA) led to the formation of five novel crystalline compounds: L-PRO±·HBTA (1), D-PRO±·HBTA (2), DL-PRO±·HBTA ( [...] Read more.
The co-crystallization of (benzylthio)acetic acid (HBTA) with L-proline (L-PRO), D-proline (D-PRO), DL-proline (DL-PRO), isonicotinamide (INA) and tryptamine (TPA) led to the formation of five novel crystalline compounds: L-PRO±·HBTA (1), D-PRO±·HBTA (2), DL-PRO±·HBTA (3), INA·HBTA (4) and TPA+·BTA (5). The prepared supramolecular assemblies were characterized by single crystal X-ray diffraction, an elemental analysis, FT-IR spectroscopy and a thermal analysis based on thermogravimetry (TG) combined with differential scanning calorimetry (DSC). Additionally, their melting points through TG/DSC measurements were established. All fabricated adducts demonstrated the same stoichiometry, displayed as 1:1. The integration of HBTA with selected N-containing co-formers yielded different forms of multi-component crystalline phases: zwitterionic co-crystals (13), true co-crystal (4) or true salt (5). In the asymmetric units of 14, the acidic ingredient is protonated, whereas the corresponding N-containing entities take either the zwitterionic form (13) or remain in the original neutral figure (4). The molecular structure of complex 5 is occupied by the real ionic forms of both components, namely the (benzylthio)acetate anion (BTA) and the tryptaminium cation (TPA+). In crystals 15, the respective molecular residues are permanently bound to each other via strong H-bonds provided by the following pairs of donor···acceptor: Ocarboxylic···Ocarboxylate and Npyrrolidinium···Ocarboxylate in 13, Ocarboxylic···Npyridine and Namine···Ocarboxylic in 4 as well as Nindole···Ocarboxylate and Naminium···Ocarboxylate in 5. The crystal structures of conglomerates 15 are also stabilized by numerous weaker intermolecular contacts, including C–H···O (13, 5), C–H···S (1, 2, 5), C–H···N (5), C–H···C (5), C–H···π (15) as well as π···π (4) interactions. The different courses of registered FT-IR spectral traces and thermal profiles for materials 15 in relation to their counterparts, gained for the pure molecular ingredients, also clearly confirm the formation of new crystalline phases. Full article
(This article belongs to the Special Issue X-ray Crystallography Based Study on Molecular Structure)
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