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Crystals
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Pharmaceutical Crystals (Volume III)
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Pharmaceutical Crystals (Volume III)

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Crystal Engineering".

Deadline for manuscript submissions: closed (30 December 2023) | Viewed by 4205

Special Issue Editors

Prof. Dr. Etsuo Yonemochi

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Guest Editor
School of Pharmacy and Pharmaceutical Sciences, Hoshi University, Tokyo 142-8501, Japan
Interests: physicochemimcal properties; physical property analysis; crystal form; polymorph prediction
Special Issues, Collections and Topics in MDPI journals
Dr. Hidehiro Uekusa

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Guest Editor
Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8551, Japan
Interests: crystallography; structure analysis; pharmaceutical crystals; phase transition
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

We are delighted to invite you to submit an article for the “Pharmaceutical Crystals (Volume III)” Special Issue of Crystals. The second Special Issue attracted much attention and successfully published ten high-quality articles; you may access all publications through this link: https://www.mdpi.com/journal/crystals/special_issues/pharmaceutical_crystals_VolumeII.  The printed book is available online from 2023. This significant success of the second Special Issue strongly indicates that the field of pharmaceutical crystals is quite attractive for many researchers. In light of this, we have decided to launch a third Special Issue in Crystals on “Pharmaceutical Crystals”.

Needless to say, the crystalline state is the most used and the most important form of solid active pharmaceutical ingredients (APIs). The characterization of pharmaceutical crystals encompasses numerous scientific disciplines, and its center is crystal structure analysis, which reveals the molecular structure of important pharmaceutical compounds and also affords key structural information that relates to the broadly variable physicochemical properties of the APIs, e.g., solubility, stability, tablet ability, color, and hygroscopicity.

The Special Issue on “Pharmaceutical Crystals” aims to publish novel molecular and crystal structures of pharmaceutical compounds. We especially encourage the submission of works of new crystal structures of APIs, including polymorphs and solvate crystals, and of multicomponent crystals of APIs, including co-crystals and salts, which would be related to changes in the physicochemical properties of pharmaceutical crystals.

This Special Issue demonstrates the importance of crystal structure information in many sectors of pharmaceutical science and engineering, and thus, contributions from both industry and academia are welcome.

Prof. Dr. Etsuo Yonemochi
Dr. Hidehiro Uekusa
Guest Editors

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. 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 2600 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

  • pharmaceutical crystals
  • co-crystals
  • salts
  • solvates
  • physicochemical properties
  • crystal engineering

Related Special Issues

Published Papers (4 papers)

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Research

18 pages, 28120 KiB  
Article
Structural Characterization and Pharmaceutical Evaluation of Telmisartan Hydrochloride Salts
by Yuda Prasetya Nugraha, I Gusti Ayu Nadia Prasta Unique, Tatsuki Miyake, Ridha Rahmah, Indra Indra, Sundani Nurono Soewandhi and Hidehiro Uekusa
Crystals 2024, 14(2), 151; https://doi.org/10.3390/cryst14020151 - 31 Jan 2024
Viewed by 887
Abstract
Telmisartan is an anti-hypertensive drug that exhibits poor aqueous solubility. In this work, salt formation was utilized to address this issue. Three hydrochloride salts of telmisartan (TELHCl), a trihemihydrate hydrochloride salt (TELHCl-Hyd), and two anhydrate forms (TELHCl-A and TELHCl-B) were obtained. The crystal [...] Read more.
Telmisartan is an anti-hypertensive drug that exhibits poor aqueous solubility. In this work, salt formation was utilized to address this issue. Three hydrochloride salts of telmisartan (TELHCl), a trihemihydrate hydrochloride salt (TELHCl-Hyd), and two anhydrate forms (TELHCl-A and TELHCl-B) were obtained. The crystal structures of TELHCl-Hyd and TELHCl-A were determined using single-crystal structure analysis. TELHCl-Hyd is a channel hydrate that has structural similarities with TELHCl-A. The structures of both crystals are mainly composed of chain structures formed by centrosymmetric dimers connected via carboxylic–benzimidazole hydrogen bonding. Despite their structural similarities, the dehydration of TELHCl-Hyd led to the formation of TELHCl-B. The solubility, intrinsic dissolution rate (IDR), powder flowability, and tabletability of TELHCl-Hyd and TELHCl-B were characterized and compared with those of the telmisartan free base form (TEL). The hydrochloride salts enhanced the solubility of telmisartan approximately 10 to 20 times and maintained the spring parachute effect up to 24 h. The IDR was also improved due to the existence of a hydrophilic channel that facilitates the dissolution of telmisartan cations. The resulting salts had a larger particle size and a more favorable crystal morphology that led to a better powder flowability. However, the tabletability was not improved by salt formation. The TEL exhibited a defined slip plane and a higher specific surface area that may assist the tableting process. Full article
(This article belongs to the Special Issue Pharmaceutical Crystals (Volume III))
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12 pages, 4581 KiB  
Article
Synthesis, Crystal Structure and Supramolecular Features of Novel 2,4-Diaminopyrimidine Salts
by Joanna Bojarska, Krzysztof Łyczko and Adam Mieczkowski
Crystals 2024, 14(2), 133; https://doi.org/10.3390/cryst14020133 - 28 Jan 2024
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Abstract
The crystal structures and the supramolecular architectures of a series of novel salts originating from 2,4-diaminopyrimidine and four different chain dicarboxylic acids are reported. For this purpose, 2,4-diaminopyrimidin-1-ium 2,2′-thio(acetic)acetate (1), 2,4-diaminopyrimidin-1-ium monoglutarate (2), 2,4-diaminopyrimidin-1-ium 3,3′-dithio(propionic)propionate (3) and [...] Read more.
The crystal structures and the supramolecular architectures of a series of novel salts originating from 2,4-diaminopyrimidine and four different chain dicarboxylic acids are reported. For this purpose, 2,4-diaminopyrimidin-1-ium 2,2′-thio(acetic)acetate (1), 2,4-diaminopyrimidin-1-ium monoglutarate (2), 2,4-diaminopyrimidin-1-ium 3,3′-dithio(propionic)propionate (3) and 2,4-diaminopyrimidin-1-ium suberate (4) were synthesized in good to high yields from 2,4-diaminopyrimidine and appropriate dicarboxylic acids (2,2′-thiodiacetic acid, glutaric acid, 3,3′-dithiodipropionic acid and suberic acid, respectively). Each of the compounds were formed as a monohydrate and compound 4 additionally co-crystallized with the suberic acid molecule. Despite the similar structures of compounds 1 and 2 as well as 3 and 4, subtle but important differences are observed in their crystal packing and H-bonding patterns, especially between 3 and 4. Supramolecular self-assemblies can be distinguished through different interactions considering anions, leading to diverse H-bonding motifs, which also include sulphur atoms in 1 and 3, at the upper level of supramolecular architecture. Notably, the basic motif is always the same—2,4-diaminopyrimidine-based homosynthon R22(8) via N-H∙∙∙N interactions. The impact of diverse types of intermolecular interactions was evaluated by Hirshfeld analysis, while the propensity of atom pairs of elements to build interactions was calculated using enrichment ratios. Although compounds 1 and 3 contain S-atoms, the percentage of S-derived interactions is rather low. In 1, the contribution of S∙∙∙H/H∙∙∙S, S∙∙∙C/C∙∙∙S, S∙∙∙N/N∙∙∙S intermolecular contacts is 5.7%. In 2, the contribution of S∙∙∙H/H∙∙∙S accounts for only 0.6%. Full article
(This article belongs to the Special Issue Pharmaceutical Crystals (Volume III))
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15 pages, 7349 KiB  
Article
Syntheses and Solid-State Characterizations of N-Alkylated Glycine Derivatives
by Darko Vušak, Mia Jurković, Neven Smrečki and Biserka Prugovečki
Crystals 2023, 13(10), 1438; https://doi.org/10.3390/cryst13101438 - 27 Sep 2023
Viewed by 785
Abstract
Seven N-alkylated glycine derivatives were prepared and characterized using single-crystal X-ray diffraction, infrared spectroscopy and thermal analysis. Chloride salts, H2EtGlyCl, H2(n-PrGly)Cl and H2(i-PrGly)Cl were prepared by aminolysis of chloroacetic acid with [...] Read more.
Seven N-alkylated glycine derivatives were prepared and characterized using single-crystal X-ray diffraction, infrared spectroscopy and thermal analysis. Chloride salts, H2EtGlyCl, H2(n-PrGly)Cl and H2(i-PrGly)Cl were prepared by aminolysis of chloroacetic acid with respective alkylamine. Nitrate salts, H2EtGlyNO3, H2(i-PrGly)NO3, H2(n-PrGly)NO3 and zwitterionic compound H(n-PrGly)·1/3H2O were prepared using ion exchange reactions from corresponding chloride salts. In all the N-alkylated glycine chloride salts, two N-alkylglycinium cations and two chloride anions were connected into centrosymmetric dimers that were additionally hydrogen bonded into endless chains. In the nitrate salts, 2D networks of different topologies were formed through hydrogen bonds between nitrate anions and N-alkylglycinium cations. In compound H(n-PrGly)·1/3H2O, the zwitterionic N-(n-propyl)glycines and water molecules of crystallization were connected into the 3D hydrogen bond networks. Chloride salts have significantly more H⋯H and O⋯C contacts than nitrate salts. All chloride salts decompose in endothermic, while nitrate salts decompose in exothermic thermal events. Full article
(This article belongs to the Special Issue Pharmaceutical Crystals (Volume III))
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14 pages, 5284 KiB  
Article
Cerium Niobate Hollow Sphere Engineered Graphitic Carbon Nitride for Synergistic Photothermal/Chemodynamic Cancer Therapy
by Kayalvizhi Samuvel Muthiah, Senthilkumar Thirumurugan, Yu-Chien Lin, Rajalakshmi Sakthivel, Udesh Dhawan, An-Ni Wang, Michael Hsiao and Ren-Jei Chung
Crystals 2023, 13(6), 954; https://doi.org/10.3390/cryst13060954 - 15 Jun 2023
Viewed by 1230
Abstract
Reactive oxygen species (ROS)-mediated chemodynamic therapy (CDT) and photothermal therapy (PTT) have potential for various cancer treatments. However, they are still bound by the demands of Fenton reaction conditions such as oxygen dependence, inherent defects in common standard photosensitizers (PSs), and the continuous [...] Read more.
Reactive oxygen species (ROS)-mediated chemodynamic therapy (CDT) and photothermal therapy (PTT) have potential for various cancer treatments. However, they are still bound by the demands of Fenton reaction conditions such as oxygen dependence, inherent defects in common standard photosensitizers (PSs), and the continuous availability of laser sources. Herein, we designed Ce3NbO7/g-C3N4 nanocomposites (NCs) and investigated their ability to evaluate the performance of PTT/CDT synergistically to enhance cancer treatment. The activation of Ce3NbO7/g-C3N4 NCs in the tumor microenvironment (TME) causes the generation of cytotoxic ROS via the Fenton reaction. Additionally, the g-C3N4 in NCs absorbs NIR, generating hyperthermia in the TME. The photothermal conversion efficiency (ƞ) of the Ce3NbO7/g-C3N4 NCs was found to be 49.5%. A photocatalytic reaction with PTT-enhanced Fenton reagents, without consuming additional photothermal agents (PTA) or Fenton reagents, generates the hydroxyl radical (OH•) primarily by direct electron transfer in the TME. Almost 68% of cells experienced programmed cell death due to the combinational effect (PTT/CDT), making it an efficient and biocompatible therapy. Furthermore, this work provides a basis for developing numerous innovative materials that can be used to treat cancer, overcome general limitations, and enhance ROS production under single-wavelength (808 nm) laser irradiation. Full article
(This article belongs to the Special Issue Pharmaceutical Crystals (Volume III))
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