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Proceedings, 2020, IOCC 2020

The 2nd International Online Conference on Crystals

Online | 10–20 November 2020

Volume Editors:
Abel Moreno, Universidad Nacional Autonoma de Mexico (UNAM), Mexico
Dritan Siliqi, Institute of Crystallography-CNR, Italy

Number of Papers: 14
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Cover Story (view full-size image): This issue of Proceedings gathers the papers that were presented at The 2nd International Online Conference on Crystals (IOCC 2020), held online on 10–20 November 2020 through the sciforum.net [...] Read more.
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9 pages, 2218 KiB  
Proceeding Paper
Hirshfeld Surface Analysis and Energy Framework for Crystals of Quinazoline Methylidene Bridged Compounds
by Akmaljon Tojiboev, Sherzod Zhurakulov, Ulli Englert, Ruimin Wang, Irmgard Kalf, Valentina Vinogradova, Kambarali Turgunov and Bakhodir Tashkhodjaev
Proceedings 2020, 62(1), 1; https://doi.org/10.3390/proceedings2020062001 - 18 Dec 2020
Cited by 3 | Viewed by 2707
Abstract
The crystal structures of 4-(3,4-dimethoxyphenylethylamino)-methylidene-2,3,4,10-tetrahydro-1H-pyrido[2,1-b]-quinazolin-10-one (1) and 4-(3,4-methylene-dioxyphenylethylamino)-methylidene-2,3,4,10-tetrahydro-1H-pyrido[2,1-b]-quina-zolin-10-one hydrochloride (2) were studied by single crystal X-ray diffraction. Their molecular and crystal structures are described in the context of intra- and inter-molecular interactions and of stereoisomerism. The crystallographic study established [...] Read more.
The crystal structures of 4-(3,4-dimethoxyphenylethylamino)-methylidene-2,3,4,10-tetrahydro-1H-pyrido[2,1-b]-quinazolin-10-one (1) and 4-(3,4-methylene-dioxyphenylethylamino)-methylidene-2,3,4,10-tetrahydro-1H-pyrido[2,1-b]-quina-zolin-10-one hydrochloride (2) were studied by single crystal X-ray diffraction. Their molecular and crystal structures are described in the context of intra- and inter-molecular interactions and of stereoisomerism. The crystallographic study established mixed E, Z configuration about the C4=C12 bond for (1) and E configuration about the C4=C12 bond for (2). For molecular crystals, Hirshfeld surface analyses may provide insight into intermolecular interactions, and energy framework analyses allow one to quantify different contributions to the overall energy. These analyses were performed to pinpoint intermolecular interactions in (1) and (2). According to our results, the molecules are associated with intra- and intermolecular hydrogen bonds, C-H···π and π-stacking interactions. The three-dimensional Hirshfeld surface analyses and two-dimensional fingerprint plots revealed that the structures are dominated by H···H, H···C/C···H and H···O/O···H contacts. The intermolecular energy analysis confirmed a significant contribution of dispersion to the stabilization of molecular packings in (1) and (2). Full article
(This article belongs to the Proceedings of The 2nd International Online Conference on Crystals)
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7 pages, 686 KiB  
Proceeding Paper
Attainment of Pentagonal-Bipyramidal LnIII Complexes from a Planar Pentadentate Ligand
by Julio Corredoira-Vázquez, Matilde Fondo, Jesús Sanmartín-Matalobos and Ana M. García-Deibe
Proceedings 2020, 62(1), 2; https://doi.org/10.3390/proceedings2020062002 - 30 Dec 2020
Cited by 2 | Viewed by 1418
Abstract
The search for mononuclear lanthanoid-based single-ion magnets (SIMs) has increased the interest in some coordination environments with low coordination numbers, in combination with an axial symmetry, as they could maximize the anisotropy of complexes of oblate lanthanoid ions, such as dysprosium(III). In this [...] Read more.
The search for mononuclear lanthanoid-based single-ion magnets (SIMs) has increased the interest in some coordination environments with low coordination numbers, in combination with an axial symmetry, as they could maximize the anisotropy of complexes of oblate lanthanoid ions, such as dysprosium(III). In this sense, the pentagonal–bipyramid geometry can have ground-state doublets with perfect axiality, and therefore such complexes can be good candidates for SIMs. In our particular case, we have used a well-known open planar pentadentate chelating Schiff base ligand as 2,6-bis(1-salicyloylhydrazonoethyl)pyridine) (H4daps) for the synthesis of air-stable pentagonal–bipyramidal LnIII complexes (these being Ln: Dy and Er, oblate and prolate, respectively), in order to compare their structures. Thus, the reaction of H4daps with (CH3)4NOH·5H2O and the corresponding LnCl3·hexahydrate has yielded heptacoordinate [(CH3)4N][LnIII(H2daps)Cl2] complexes, where the tetramethylammonium cation is acting as the counterion of pentagonal–bipyramidal LnIII complexes, which are bearing two chloride atoms in apical positions. As both complexes could be crystallized as single crystals, we can compare their crystal structures, as well as with some other related complexes in the literature, which contain different counterions, trying to see their influence on other properties of the compounds, such as their magnetic behavior. Full article
(This article belongs to the Proceedings of The 2nd International Online Conference on Crystals)
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4 pages, 710 KiB  
Proceeding Paper
New Quaternary Chalcogenides Tl2MIIMIV3Se8 and Tl2MIIMIVX4
by Andrii Selezen, Yuri Kogut, Lyudmyla Piskach and Lubomir Gulay
Proceedings 2020, 62(1), 3; https://doi.org/10.3390/proceedings2020062003 - 31 Dec 2020
Viewed by 1463
Abstract
New quaternary thallium-containing chalcogenides Tl2MIIMIV3X8 and Tl2MIIMIVX4 were synthesized, and their crystal structure was determined by XRD. Three Tl2MIIMIV3X8 chalcogenides [...] Read more.
New quaternary thallium-containing chalcogenides Tl2MIIMIV3X8 and Tl2MIIMIVX4 were synthesized, and their crystal structure was determined by XRD. Three Tl2MIIMIV3X8 chalcogenides crystallize in orthorhombic symmetry (S.G. P212121; Tl2CdGe3Se8 lattice parameters a = 0.76023(9), b = 1.2071(2), c = 1.7474(2) nm), eight isostructural Tl2BIIDIVX4 compounds crystallize in tetragonal symmetry, S.G. I-42m. These compounds form in the quasi-ternary systems Tl2X–MIIX–MIVX2 (X–S, Se, Te) at the component ratio 1:1:1 and 1:1:3 at the sections Tl2MIVX3–BIIX and Tl2MIIMIVX4–MIVX2, respectively. The composition of the Tl2CdGe3Se8 compound was additionally confirmed by SEM and EDS. Full article
(This article belongs to the Proceedings of The 2nd International Online Conference on Crystals)
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6 pages, 628 KiB  
Proceeding Paper
Photoconductivity of the Single Crystals Pb4Ga4GeS12 and Pb4Ga4GeSe12
by Hadj Bellagra, Oksana Nyhmatullina, Yuri Kogut, Halyna Myronchuk and Lyudmyla Piskach
Proceedings 2020, 62(1), 4; https://doi.org/10.3390/proceedings2020062004 - 31 Dec 2020
Viewed by 1320
Abstract
Quaternary semiconductor materials of the Pb4Ga4GeS(Se)12 composition have attracted the attention of researchers due to their possible use as active elements of optoelectronics and nonlinear optics. The Pb4Ga4GeS(Se)12 phases belong to the solid [...] Read more.
Quaternary semiconductor materials of the Pb4Ga4GeS(Se)12 composition have attracted the attention of researchers due to their possible use as active elements of optoelectronics and nonlinear optics. The Pb4Ga4GeS(Se)12 phases belong to the solid solution ranges of the Pb3Ga2GeS(Se)8 compounds which form in the quasi-ternary systems PbS(Se)−Ga2S(Se)3−GeS(Se)2 at the cross of the PbGa2S(Se)4−Pb2GeS(Se)4 and PbS(Se)−PbGa2GeS(Se)6 sections. The quaternary sulfide melts congruently at 943 K. The crystallization of the Pb4Ga4GeSe12 phase is associated with the ternary peritectic process Lp + PbSe ↔ PbGa2S4 + Pb3Ga2GeSe8 at 868 K. For the single crystal studies, Pb4Ga4GeS(Se)12 were pre-synthesized by co-melting high-purity elements. The X-ray diffraction results confirm that these compounds possess non-centrosymmetric crystal structure (tetragonal symmetry, space group P–421c). The crystals were grown by the vertical Bridgman method in a two-zone furnace. The starting composition was stoichiometric for Pb4Ga4GeS12, and the solution-melt method was used for the selenide Pb4Ga4GeSe12. The obtained value of the bandgap energy for the Pb4Ga4GeS12 and Pb4Ga4GeSe12 crystals is 1.86 and 2.28 eV, respectively. Experimental measurements of the spectral distribution of photoconductivity for the Pb4Ga4GeS12 and Pb4Ga4GeSe12 crystals exhibit the presence of two spectral maxima. The first lies in the region of 570 (2.17 eV) and 680 nm (1.82 eV), respectively, and matches the optical bandgap estimates well. The locations of the admixture maxima at about 1030 (1.20 eV) and 1340 nm (0.92 eV), respectively, agree satisfactorily with the calculated energy positions of the defects vs. and VSe. Full article
(This article belongs to the Proceedings of The 2nd International Online Conference on Crystals)
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8 pages, 543 KiB  
Proceeding Paper
Polyproline-Rich Peptides Organize Four Cholinesterase Subunits into a Tetramer; BChE and AChE Scavenge Polyproline Peptides Released during Metabolic Turnover
by Oksana Lockridge and Lawrence M. Schopfer
Proceedings 2020, 62(1), 5; https://doi.org/10.3390/proceedings2020062005 - 31 Dec 2020
Viewed by 1459
Abstract
The genes for acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) encode the proteins responsible for enzyme activity. Additional gene products, PRiMA and ColQ, anchor AChE and BChE proteins into membranes. Soluble AChE and BChE tetramers are composed of four identical subunits plus one polyproline-rich peptide. [...] Read more.
The genes for acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) encode the proteins responsible for enzyme activity. Additional gene products, PRiMA and ColQ, anchor AChE and BChE proteins into membranes. Soluble AChE and BChE tetramers are composed of four identical subunits plus one polyproline-rich peptide. Dilution does not release the polyproline-rich peptide from tetramers. However, protein denaturation, for example, heating in a boiling water bath, dissociates the polyproline-rich peptide. Using mass spectrometry to sequence peptides released from soluble AChE and BChE tetramers, we find sequences that correspond to proline-rich regions from a variety of proteins. A typical peptide sequence contains 20 consecutive prolines in a 23-residue peptide, LPPPPPPPPPPPPPPPPPPPPLP. There is no single, common consensus sequence, i.e., no specific gene appears to be responsible for the polyproline-rich peptides found in soluble AChE and BChE tetramers. We propose that during metabolic turnover, protein fragments containing polyproline-rich sequences are scavenged by AChE and BChE dimers, to make stable AChE and BChE tetramers. The 40-residue, alpha-helical C-terminus of AChE or BChE is the tetramerization domain that binds the polyproline-rich peptide. Four parallel alpha helices wrap around a single antiparallel polyproline peptide to lock the tetramer in place. This organization was established by classical X-ray crystallography for isolated C-termini in complex with a proline-rich peptide. The organization was confirmed for intact, tetrameric human BChE using cryoelectron microscopy. When 40 amino acids are deleted from the carboxy terminus, monomeric enzymes are created that retain full enzymatic activity. Full article
(This article belongs to the Proceedings of The 2nd International Online Conference on Crystals)
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12 pages, 1664 KiB  
Proceeding Paper
Acid-free Hydrothermal Process for Synthesis of Bioactive Glasses 70SiO2–(30-x)CaO–xZnO (x = 1, 3, 5 mol.%)
by Ta Anh Tuan, Elena V. Guseva, Le Hong Phuc, Nguyen Quan Hien, Nguyen Viet Long and Bui Xuan Vuong
Proceedings 2020, 62(1), 6; https://doi.org/10.3390/proceedings2020062006 - 31 Dec 2020
Cited by 2 | Viewed by 1839
Abstract
Bioactive glasses 70SiO2–(30-x)CaO–xZnO (x = 1, 3, 5 mol.%) were prepared by the acid-free hydrothermal method in keeping with green chemical technology. The synthetic glasses were investigated by TG-DSC, BET, XRD, and SEM–EDX methods. All synthetic glasses present mesoporous structures consisting [...] Read more.
Bioactive glasses 70SiO2–(30-x)CaO–xZnO (x = 1, 3, 5 mol.%) were prepared by the acid-free hydrothermal method in keeping with green chemical technology. The synthetic glasses were investigated by TG-DSC, BET, XRD, and SEM–EDX methods. All synthetic glasses present mesoporous structures consisting of aggregates of nanoparticles. The bioactivity of synthetic glasses was confirmed through the formation of the hydroxyapatite phase after an in vitro experiment in simulated body fluid (SBF) solution. The effect of Zn addition is shown through the decrease in the bioactivity of synthetic glasses. Additionally, the inductively coupled plasma optical emission spectrometry (ICP-OES) analysis indicates that the Zn ions were released from the glassy networks during in vitro experiments, and they act as Zn(OH)2 suspended precipitation to inhibit the apatite deposition. The in vitro experiment in cell culture matter was performed for SaOS2 and Eahy929 cells. The results confirm the biocompatibility of synthetic glasses and the role of Zn addition in the proliferation of living cells. Full article
(This article belongs to the Proceedings of The 2nd International Online Conference on Crystals)
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8 pages, 476 KiB  
Proceeding Paper
Systematic Model-Based Steady State and Dynamic Optimization of Combined Cooling and Antisolvent Multistage Continuous Crystallization Processes
by Jiaxu Liu and Brahim Benyahia
Proceedings 2020, 62(1), 7; https://doi.org/10.3390/proceedings2020062007 - 31 Dec 2020
Cited by 1 | Viewed by 1564
Abstract
Currently, one of the key challenges in the pharmaceutical industry is the transformation of traditional batch production methods into robust continuous processes with the intention of reducing manufacturing costs and time and improving product quality. Crystallization is by far the most important purification [...] Read more.
Currently, one of the key challenges in the pharmaceutical industry is the transformation of traditional batch production methods into robust continuous processes with the intention of reducing manufacturing costs and time and improving product quality. Crystallization is by far the most important purification technology in Pharma, as more than 80% of the active pharmaceutical ingredients (API) require at least one crystallization step. A successful crystallization process requires tight control over crystal size, shape and polymorphic purity. A rigorous and systematic methodology is presented to design and optimize multistage combined cooling and antisolvent continuous (mixed-suspension, mixed-product removal- MSMPR) crystallizers. The crystallization of acetylsalicylic acid (API) in ethanol (solvent) and water (anti-solvent) is used as a case study. A predictable and validated mathematical model of the system, which consists of a one-dimensional population balance model, was used to develop several optimizations strategies. Firstly, the attainable region of the mean particle size was determined for both minimum and maximum attainable crystal size. The method helped identify the most suitable number of stages and total residence time or volume for a cascade of continuous crystallizers. This was followed by a steady state optimization which helped determine the optimal operating temperatures and antisolvent flowrates. To minimize the startup time, a series of dynamic optimization strategies were implemented, assuming starting from empty vessels. The optimal dynamic profiles of the temperature and antisolvent flow rate, at different crystallization steps, were identified using a systematic and rigorous approach allowing a reduction in the startup time by 31%. Full article
(This article belongs to the Proceedings of The 2nd International Online Conference on Crystals)
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8 pages, 796 KiB  
Proceeding Paper
Mathematical Tools that Connect Different Indexing Analyses
by Ryoko Oishi-Tomiyasu
Proceedings 2020, 62(1), 8; https://doi.org/10.3390/proceedings2020062008 - 31 Dec 2020
Viewed by 1448
Abstract
As mathematical tools that can be commonly used for indexing analyses from different types of experimental patterns, we have recently developed (i) rules on forbidden hkl’s that can be used even when the space group and setting are unknown, (ii) an algorithm [...] Read more.
As mathematical tools that can be commonly used for indexing analyses from different types of experimental patterns, we have recently developed (i) rules on forbidden hkl’s that can be used even when the space group and setting are unknown, (ii) an algorithm for error-stable Bravais lattice determination, (iii) generalization of the de Wolff figure of merit for powder diffraction (1D data) to data in higher-dimensions such as Kikuchi patterns (2D data) by electron backscatter diffraction (EBSD). In particular, (ii) could be used in a variety of situations, not just for indexing. It is explained how (i)–(iii) are used in the mathematical framework of our indexing algorithms. Full article
(This article belongs to the Proceedings of The 2nd International Online Conference on Crystals)
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10 pages, 2080 KiB  
Proceeding Paper
XRD Data Visualization, Processing and Analysis with d1Dplot and d2Dplot Software Packages
by Oriol Vallcorba and Jordi Rius
Proceedings 2020, 62(1), 9; https://doi.org/10.3390/proceedings2020062009 - 31 Dec 2020
Viewed by 3590
Abstract
The d1Dplot and d2Dplot computer programs have been developed as user-friendly tools for the inspection and processing of 1D and 2D X-ray diffraction (XRD) data, respectively. d1Dplot provides general tools for data processing and includes the ability to generate comprehensive 2D plots of [...] Read more.
The d1Dplot and d2Dplot computer programs have been developed as user-friendly tools for the inspection and processing of 1D and 2D X-ray diffraction (XRD) data, respectively. d1Dplot provides general tools for data processing and includes the ability to generate comprehensive 2D plots of multiple patterns to easily follow transformation processes. d2Dplot is a full package for 2D XRD data. Besides general processing tools, it includes specific data analysis routines for the application of the through-the-substrate methodology [Rius et al. IUCrJ 2015, 2, 452–463]. Both programs allow the creation of a user compound database for the identification of crystalline phases. The software can be downloaded from the ALBA Synchrotron Light Source website and can be used free of charge for non-commercial and academic purposes. Full article
(This article belongs to the Proceedings of The 2nd International Online Conference on Crystals)
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8 pages, 512 KiB  
Proceeding Paper
Evaluating the Concentration of Ions in Liquid Crystal Cells: Hidden Factors and Useful Techniques
by Yuriy Garbovskiy
Proceedings 2020, 62(1), 10; https://doi.org/10.3390/proceedings2020062010 - 1 Jan 2021
Cited by 2 | Viewed by 1961
Abstract
Many liquid crystal devices are driven by electric fields. Ions, typically present in molecular liquid crystal materials in minute quantities, can compromise the performance of mesogenic materials (in the simplest case, through a well-known screening effect). Even highly purified liquid crystals can be [...] Read more.
Many liquid crystal devices are driven by electric fields. Ions, typically present in molecular liquid crystal materials in minute quantities, can compromise the performance of mesogenic materials (in the simplest case, through a well-known screening effect). Even highly purified liquid crystals can be contaminated with ions during their production and handling. Therefore, measurements of the concentration of ions have become an important part of the material characterization of liquid crystals. Interestingly, even a brief analysis of existing publications can reveal a quite broad variability of the values of the concentration of ions measured by different research groups for the same liquid crystals. This reflects the complexity of ion generation mechanisms in liquid crystal materials and their dependence on numerous factors. In this paper, an overview of ion generation mechanisms in liquid crystals and modern ion measurement techniques is followed by the discussion of frequently overlooked factors affecting the measured values of the ion concentration. Ion-generating and ion-capturing properties of the alignment layers (or substrates) of liquid crystal cells are considered and used to evaluate a true concentration of ions in liquid crystals. In addition, practical recommendations aimed at improving the measurements of the ion density in liquid crystals are also discussed. Full article
(This article belongs to the Proceedings of The 2nd International Online Conference on Crystals)
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10 pages, 664 KiB  
Proceeding Paper
Functional Nano-Hydroxyapatite for Applications in Conservation of Stony Monuments of Cultural Heritage
by Francesco Capitelli, Bujar Dida, Giancarlo Della Ventura, Francesco Baldassarre, Davide Capelli, Giorgio S. Senesi, Altin Mele and Dritan Siliqi
Proceedings 2020, 62(1), 11; https://doi.org/10.3390/proceedings2020062011 - 4 Jan 2021
Cited by 3 | Viewed by 1845
Abstract
Stony monuments must continuously be safeguarded from damage caused over time, in particular from the detrimental effects of weathering. One of the new environmentally-friendly (nano) materials for stone reinforcement, particularly suitable for marble and calcareous (limestone, sandstone) artifacts, is Ca10(PO4 [...] Read more.
Stony monuments must continuously be safeguarded from damage caused over time, in particular from the detrimental effects of weathering. One of the new environmentally-friendly (nano) materials for stone reinforcement, particularly suitable for marble and calcareous (limestone, sandstone) artifacts, is Ca10(PO4)6(OH)2 hydroxyapatite (HAp), which has a considerably lower dissolution rate and solubility compared to CaCO3 calcite (the building block of marble materials): thus, HAp has been proposed for the protection of calcareous monuments against acidic rain corrosion. Promising results have been obtained, but further optimization is necessary as the treated layer is often incomplete, cracked and/or porous. Several parameters need to be optimized, in this way a homogeneous layer can be obtained, and consequently the formation of metastable can be avoided, soluble phases instead of HAp. These include: the pH of the starting solution; the effect of organic and inorganic additions in particular, that of ethanol, which is known to adsorb calcite, thus possibly favoring the growth of the HAp layer. The formation of HAp nanoparticles and their application on stony substrates has been investigated by means of a multi-methodological approach based on scanning electron microscopy, x-ray diffraction, small- and/or wide-angle x-ray scattering, Fourier-transform infrared spectroscopy, and finally, in situ measurements of laser-induced breakdown spectroscopy and acid attack preliminary tests on stony substrates. Full article
(This article belongs to the Proceedings of The 2nd International Online Conference on Crystals)
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4 pages, 250 KiB  
Proceeding Paper
Cocrystals of Modafinil-Nicotinic Acid: A Novel Cocrystal for Enhanced Bioavailability
by Tanmoy Ghosh, Thimmasetty Juturu, Shashank Nayak Nagar and Shwetha Kamath
Proceedings 2020, 62(1), 12; https://doi.org/10.3390/proceedings2020062012 - 13 Jan 2021
Cited by 1 | Viewed by 2051
Abstract
In this work, we are the first to identify and report pharmaceutically effective cocrystals of the poorly soluble drug Modafinil (MOD) using a crystal engineering approach. A multi-component system of MOD with nicotinic acid (NIC) as the coformer at a 1:1 molar ratio [...] Read more.
In this work, we are the first to identify and report pharmaceutically effective cocrystals of the poorly soluble drug Modafinil (MOD) using a crystal engineering approach. A multi-component system of MOD with nicotinic acid (NIC) as the coformer at a 1:1 molar ratio was prepared to simultaneously improve the solubility, dissolution and bioavailability by applying a liquid assistant grinding technique. Nicotinic acid as a potential coformer for cocrystal preparation was predicted using a novel approach of the Hansen Solubility Parameter (HSP) group contribution method. Various evaluation parameters pertaining to confirm cocrystal formation, such as Fourier transformer infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and field emission scanning electron microscopy (FESEM) were carried out. Further effects of precipitation inhibitor Hydroxypropyl methyl cellulose (HPMC) on in-vivo bioavailability enhancement were also studied. MOD-NIC cocrystals formation was confirmed by integrating the results of instrumental techniques. Aqueous solubility and in-vivo pharmacokinetic study proved 5.96 and 1.88 times higher bioavailability, respectively, in the case of prepared cocrystals compared to MOD alone, whereas bioavailability further increased by 2.72 times when these cocrystals were administered in the presence of precipitation inhibitor. Hence, solid state manipulation was successful for preparing modafinil cocrystals as a potential method for illustrating several properties. The concept of cocrystals coupled with precipitation inhibitors significantly enhanced the bioavailability of modafinil. Full article
(This article belongs to the Proceedings of The 2nd International Online Conference on Crystals)
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8 pages, 1497 KiB  
Proceeding Paper
Synthesis and X-ray Diffraction Study of thiosemicarbazone Palladacycles with dppm
by Marcos Rúa-Sueiro, Paula Munin-Cruz, Francisco Reigosa, José M. Vila and Juan M. Ortigueira
Proceedings 2020, 62(1), 13; https://doi.org/10.3390/proceedings2020062013 - 22 Jan 2021
Viewed by 1529
Abstract
Cyclometallated compounds have been extensively studied, in particular those with palladium and platinum. This is because of their possible applications in medicinal chemistry, as anticancer or antimicrobial agents; in some cases, with similar results as cisplatin, carboplatin or oxaliplatin. What is also remarkable [...] Read more.
Cyclometallated compounds have been extensively studied, in particular those with palladium and platinum. This is because of their possible applications in medicinal chemistry, as anticancer or antimicrobial agents; in some cases, with similar results as cisplatin, carboplatin or oxaliplatin. What is also remarkable is their use as homogeneous catalysts, for example, in cross coupling reactions such as Suzuki–Miyaura or Mizoroki–Heck. Herein, we report the synthesis of different thiosemicarbazone ligands, which will be reacted with a palladium or platinum salt, to give the corresponding cyclometallated compounds; in addition, their reactivity with bis(diphenylphosphino)methane (dppm) will be studied. Characterization has been carried out by elemental analysis, IR spectroscopy, 1H and 31P NMR spectroscopy. Additionally, 1c has been studied by X-ray diffraction. Full article
(This article belongs to the Proceedings of The 2nd International Online Conference on Crystals)
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14 pages, 586 KiB  
Proceeding Paper
Pharmaceutical Cocrystals—A Review
by Sheetal S. Buddhadev and Kevin C. Garala
Proceedings 2020, 62(1), 14; https://doi.org/10.3390/proceedings2020062014 - 8 Mar 2021
Cited by 14 | Viewed by 5364
Abstract
The design and synthesis of pharmaceutical cocrystals have received great interest in the recent years. Cocrystallization of drug substances offers a tremendous opportunity for the development of new drug products with superior physical and pharmacological properties such as solubility, stability, hydroscopicity, dissolution rates [...] Read more.
The design and synthesis of pharmaceutical cocrystals have received great interest in the recent years. Cocrystallization of drug substances offers a tremendous opportunity for the development of new drug products with superior physical and pharmacological properties such as solubility, stability, hydroscopicity, dissolution rates and bioavailability. This short review summarizes this highly topical field, covering why the topic is of interest in pharmaceutical formulation, the definitions and practical scope of cocrystals, cocrystal preparation and characterization, a comparison of different (traditional and novel) methods for cocrystal formation and the implications for regulatory control and intellectual property protection. Traditionally, cocrystals can be prepared by solvent evaporation method, grinding, and slurry method, but every method has its limitations for certain conditions. The current trend for cocrystal formation uses sophisticated methods such as the hot melt extrusion method, spray-drying method, supercritical fluid technology and the newest method: laser irradiation. The purpose of the development of a new method is not only to overcome the limitation of traditional cocrystallization methods, but also to generate simpler steps and a continuous process for the production of the cocrystal product. This article provides a brief explanation of each method that can be used to generate pharmaceutical cocrystals as well as evaluation of cocrystals. This article also covers how the developing field of cocrystallization may impact the pharmaceutical intellectual property landscape. Full article
(This article belongs to the Proceedings of The 2nd International Online Conference on Crystals)
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