Article
Chemistry, Inorganic & Nuclear
Zenji Hiroi
Summary: Apart from the rutile structure, titanium dioxide also exists in anatase, brookite, and alpha-PbO2-type structures. These structures are distinguished by the linkage pattern of the TiO6 octahedra and their stacking arrangements. By analyzing the anion close packings, the relationships among these structures can be better understood.
INORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Jamshed Haneef, Datta Markad, Renu Chadha, Amit Kumar, Navin Kumar
Summary: The mechanical properties of drug molecules are important for their processing into finished products. This study focuses on the mechanical anisotropy in two polymorphs of ambrisentan. Nanoindentation experiments showed that form I has higher hardness and elastic modulus compared to form II. The differences in mechanical properties were explained by differences in crystal structure and intermolecular interactions. Overall, form II exhibited higher plasticity and tabletability than form I. This study highlights the importance of crystal structure in determining the mechanical performance of drug crystals.
Article
Crystallography
Yan-Fang Wu, Hao Zhang, Nai-Xing Wang, Tian Chen, Yan Liu
Summary: Valacyclovir hydrochloride, an antiviral drug, has multiple crystal forms including sesquihydrate, anhydrous Form I, and Form II. This study investigates the dehydration process of sesquihydrate and the transformations between different crystal forms, revealing the mechanisms of these transition processes and establishing the crystal transformation relationship of the mentioned forms.
CRYSTAL RESEARCH AND TECHNOLOGY
(2021)
Article
Chemistry, Physical
Jiequn Tang, Yanqiang Han, Imran Ali, Hongyuan Luo, Andrzej Nowak, Jinjin Li
Summary: The study found that olanzapine undergoes polymorphic phase transformations, with form I being the most stable, form II being the least stable, and form IV being more stable than form III below 200K. This research may help explain the recent discovery of form IV crystallizing from a polymer-based molecular dispersion and provide experimental guidance for studying phase transitions of pharmaceutical molecules.
CHEMICAL PHYSICS LETTERS
(2021)
Article
Chemistry, Physical
M. Laanaiya, A. Bouibes, A. Zaoui
Summary: The study investigates the properties of gamma- beta- polymorphic forms of belite, highlighting the higher water reactivity of beta-belite compared to gamma-belite. The research also finds similarities in mechanical properties between the two belite phases, with gamma-belite predicted to be slightly more rigid and resistant to mechanical loading than beta-belite.
SOLID STATE IONICS
(2021)
Article
Chemistry, Multidisciplinary
Evgeny Gerber, Anna Krot, Karina Andreadi, Alexey Averin, Andrey Shiryaev, Alexander Trigub, Nikita Sobolev, Iurii Nevolin
Summary: Uranium hydrazinates with a poorly crystalline layered structure have been synthesized and their phase transitions upon heating have been studied. It has been found that the elemental composition of U(vi) hydrazinate can be described as UO3·0.3N2H4·1.7H2O. The thermal treatment of xUO3·yN2H4·zH2O is secure and applicable for nuclear technology due to the weak exothermic effect and absence of combustible gases.
NEW JOURNAL OF CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Su Xue, Jipeng Xu, You Han, Jinli Zhang, Wei Li
Summary: Imidacloprid (IMI) polymorphs were found to be sensitive to the content of antisolvent in a crystallization process. The molecular packing modes of IMI change with the ratio of formic acid (FA) to water (W). Increasing water content promotes conformation change of IMI and facilitates nucleation for Form I.
CRYSTAL GROWTH & DESIGN
(2021)
Review
Chemistry, Multidisciplinary
Yiyao Ge, Biao Huang, Lujiang Li, Qinbai Yun, Zhenyu Shi, Bo Chen, Hua Zhang
Summary: The structural transformation of materials under external conditions is an important phenomenon that has attracted significant research interest. Recently, materials with unconventional phases different from their thermodynamically stable counterparts have been shown to possess distinct properties and can serve as starting materials for further studies. This article summarizes the recent progress in the structural transformation of unconventional-phase starting materials induced by different approaches, including metastable crystalline phase, amorphous phase, and heterophase. The importance of these starting materials in the modulation of resultant structures is highlighted, along with the use of in situ/operando characterization techniques and theoretical simulations.
Article
Crystallography
Guangyan Li, Ting Wang, Xin Huang, Na Wang, Lina Zhou, Beiqian Tian, Ziwei Feng, Ailing Liu, Yaling Li, Hongxun Hao
Summary: A comprehensive crystal structure analysis of fluralaner was conducted to study the thermodynamic stability, phase transformation, and selective nucleation mechanisms of different polymorphs. Various analytical techniques were used to characterize Form I, Form II, and Form III, revealing structural similarity between Form I and Form III but unique molecular conformation and packing pattern in Form II. The thermodynamic stability order was found to be Form II > Form I > Form III and the selective nucleation of similar structures was affected by the addition of n-hexane.
Article
Engineering, Environmental
Shiwen Hu, Hanyue Zhang, Yang Yang, Weiqi Wang, Wenjing Zhou, Xinyue Shen, Chongxuan Liu
Summary: The coupled kinetics of Cr-(VI) reduction and immobilization of Cr-(III) and organic matter (OM) during dissimilatory iron reduction contributes to the synchronous sequestration of heavy metals and organic matter in soil environments. The reductive sequestration of Cr-(VI) and immobilization of fulvic acid (FA) during the microbially mediated phase transformation of ferrihydrite were investigated. The resulting Cr-(III) was incorporated into magnetite and goethite, while OM was mainly adsorbed on goethite and magnetite surfaces and located within pore spaces.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2023)
Article
Chemistry, Inorganic & Nuclear
Takuya Hatakeyama, Norihiko L. Okamoto, Tetsu Ichitsubo
Summary: This study investigates the thermal stability of alpha, beta, gamma, delta, and lambda-type MnO2 polymorphs using DSC and HTXRD. Results show that the thermal stability order of the polymorphs is beta > alpha > gamma > delta approximate to lambda. The structure and phase transformations of each phase under high temperature conditions are discussed in relation to the bonding environment of oxide ions.
JOURNAL OF SOLID STATE CHEMISTRY
(2022)
Article
Materials Science, Ceramics
Huicong Cheng, Yalei Wang, Huaifei Liu, Xiang Xiong, Yulin Tan
Summary: In this study, dysprosia stabilized zirconia (DySZ) powders with nano-sized metastable tetragonal-phase structure were synthesized. The phase transformation of DySZ during heat treatment was investigated and found to follow the new phase nucleation and growth theory. Elevated ambient temperature was shown to accelerate the phase transformation process.
CERAMICS INTERNATIONAL
(2022)
Review
Virology
Christiane Riedel, Hazel Aitkenhead, Kamel El Omari, Till Ruemenapf
Summary: The genus pestivirus has been expanding for the past two decades, with the host range now extending to rodents, bats, and marine mammals. This review focuses on atypical porcine pestivirus or pestivirus K, comparing its unique traits to other pestiviruses known at the structural and functional level.
Article
Chemistry, Physical
Jessica Satta, Claudio Melis, Carlo Maria Carbonaro, Andrea Pinna, Manuel Salado, Daniel Salazar, Pier Carlo Ricci
Summary: This paper proposes using Raman spectroscopy as a fast and reliable experimental tool to assess the crystal structure of lead halide perovskite samples, and studying the mechanisms of laser-induced phase degradation through in-situ Raman measurements. The vibrational analysis and comparison of experimental spectra to Raman modes calculated within the DFT framework can help identify the polymorph of the sample and provide new insights on secondary phases generated during the process.
JOURNAL OF MATERIOMICS
(2021)
Article
Chemistry, Multidisciplinary
Ann Maria James, Alessandro Greco, Felix Devaux, Nemo Mcintosh, Patrick Brocorens, Jerome Cornil, Priya Pandey, Birgit Kunert, Lucia Maini, Yves Henri Geerts, Roland Resel
Summary: This work provides a comprehensive illustration of the crystalline melt memory effect observed in three solvates of the 2,7-bis(2-(2-methoxyethoxy)ethoxy)benzo[b]benzo[4,5] thieno[2,3-d]thiophene (OEG-BTBT) molecule with dichloromethane (DCM) molecules. The strong interaction between DCM molecules and oligoethylene glycol side chains is found to be the key factor leading to the observed melt memory effect.
CRYSTAL GROWTH & DESIGN
(2023)
Article
Chemistry, Inorganic & Nuclear
Lukas Fliri, Thomas Gelbrich, Ulrich J. Griesser, Gabriel Partl, Felix R. S. Purtscher, Sandro Neuner, Kevin Erharter, Klaus Wurst, Volker Kahlenberg, Doris E. Braun, Thomas S. Hofer, Albert Rossler, Herwig Schottenberger
Summary: A series of new metathetical salts were prepared using an expedient anion exchange protocol, with a focus on crystallographic and thermal characterization. Experimental and computational studies revealed differences in thermal decomposition behavior between azido and methyl salts.
ZEITSCHRIFT FUR ANORGANISCHE UND ALLGEMEINE CHEMIE
(2021)
Article
Materials Science, Ceramics
Hang Liu, Elias Hildebrandt, Hans Krammer, Volker Kahlenberg, Hannes Kruger, Herwig Schottenberger
Summary: Polycrystalline K4CaSi6O15 was prepared through solid-state reactions or combustion solution synthesis, exhibiting a glass-forming tendency. It has a monoclinic structure with interrupted framework silicates, existing stably in the K2O-CaO-SiO2 ternary system.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2021)
Article
Chemistry, Physical
Dawn R. Chaffey, Takudzwa Bere, Thomas E. Davies, David C. Apperley, Stuart H. Taylor, Andrew E. Graham
Summary: This study presents a novel strategy for the efficient synthesis of levulinate esters using commercial catalysts, ZSM-5 and Amberlyst-15, under mild conditions and short reaction times, resulting in high yields and selectivity.
APPLIED CATALYSIS B-ENVIRONMENTAL
(2021)
Article
Materials Science, Multidisciplinary
Volker Kahlenberg, Hannes Krueger, Martina Tribus
Summary: The effect of Fe <-> Al substitution on triclinic SFCA-I-type compounds with general formula A(40)O(56) has been studied using single-crystal X-ray diffraction, showing significant structural changes with increasing Al/Fe-Tot ratios. The major contraction perpendicular to the pyroxene and spinel modules is observed as the Al content increases. This study provides a detailed crystallographic analysis on the impact of chemical variations in a compound relevant to iron-ore sintering.
PHYSICS AND CHEMISTRY OF MINERALS
(2021)
Article
Chemistry, Multidisciplinary
Predrag Dabic, Volker Kahlenberg, Biljana Krueger, Marko Rodic, Sabina Kovac, Jovan Blanusa, Zvonko Jaglicic, Ljiljana Karanovic, Vaclav Petricek, Aleksandar Kremenovic
Summary: A new ambient-temperature hexagonal polymorph of tripotassium ytterbium(III) disilicate has been synthesized and found to undergo a phase transformation to a novel low-temperature orthorhombic phase. The two crystal forms have distinct structures, each composed of specific layers. Magnetic characterization suggests that the phase transformation does not significantly impact the magnetic properties of the compound.
ACTA CRYSTALLOGRAPHICA SECTION B-STRUCTURAL SCIENCE CRYSTAL ENGINEERING AND MATERIALS
(2021)
Article
Chemistry, Multidisciplinary
Doris E. Braun, Patricia Hald, Volker Kahlenberg, Ulrich J. Griesser
Summary: Two bipyridine isomers (2,2'- and 4,4'-) exhibit different crystallization behavior and properties during solid form screening and crystal structure prediction, with the 4,4'-isomer forming multiple solvates and anhydrate due to its molecular structure. The study results indicate that there are differences in the crystallization behavior of the two isomers.
CRYSTAL GROWTH & DESIGN
(2021)
Article
Geochemistry & Geophysics
Volker Kahlenberg, Lukas Prosser, Michael F. Salzmann, Clivia Hejny
Summary: The study focuses on Sr-substitution in the crystal structure of bredigite, investigating the effect of different Sr contents on the unit-cell parameters and site preferences. Various solid-solution series were synthesized and characterized to reveal the structural changes induced by the replacement of calcium atoms with strontium atoms.
MINERALOGY AND PETROLOGY
(2022)
Article
Chemistry, Organic
Thomas Gelbrich, Klaus Wurst, Paul Mayer, Herwig Schottenberger, Sven Nerdinger
Summary: The molecule of the title compound has a twisted geometry, with a rotation of approximately 30 degrees between the mean planes of the imidazole and phenyl rings. The crystal structure exhibits hydrogen bonded chains due to N-H···N interactions between imidazole rings of neighboring molecules. These chains are assembled into flat molecular layers parallel to the (121) plane. Two intermolecular interactions, involving inversion-related molecules belonging to adjacent molecular layers, contribute significantly to crystal stabilization.
Article
Crystallography
Sandro Neuner, Thomas Gelbrich, Klaus Wurst, Josef Spreitz, Sven Nerdinger, Ulrich J. Griesser, Marijan Stefinovic, Herwig Schottenberger
Summary: This study reports a compound called 2,6-diamino-5-[(2-cyclopropyl-7,8-dimethoxy-2H-1-benzopyran-5-yl)methyl]pyrimidin-1-ium methanesulfonate. It consists of a protonated iclaprim molecule and a mesylate anion. The pyrimidine and chromene units of the iclaprim molecule form an orthogonal arrangement and are connected through multiple hydrogen bonds with the mesylate molecules, resulting in an infinite hydrogen-bonded molecular tape structure.
ACTA CRYSTALLOGRAPHICA SECTION E-CRYSTALLOGRAPHIC COMMUNICATIONS
(2023)
Article
Chemistry, Organic
Weronika Kozanecka-Okupnik, Klaus Wurst, Sandro Neuner, Sven Nerdinger, Thomas Gelbrich
Summary: The dihydrochloride salt of pexidartinib was synthesized and its crystal structure was determined. The molecule forms N-H···O and N-H···Cl interactions with water molecules and chloride ions, respectively. The intermolecular interactions result in a complex H-bonded framework structure.
Article
Crystallography
Jascha Schinke, Thomas Gelbrich, Ulrich J. Griesser
Summary: In the molecule of isoxaflutole, the 1,2-oxazole and methanone fragments form a near coplanar structure, while the methanone and phenyl groups are inclined at an angle of more than 60 degrees. This conformation is different from all other known examples of the 1,2-oxazol-4-yl(phenyl)methanone fragment and is due to the presence of a bulky substituent at the phenyl ring. The stability of the crystal is mainly attributed to a columnar arrangement of molecules along the twofold screw axis and interactions between adjacent columns related by an inversion operation.
ACTA CRYSTALLOGRAPHICA SECTION E-CRYSTALLOGRAPHIC COMMUNICATIONS
(2022)
Article
Chemistry, Organic
Sandro Neuner, Heidi A. Schwartz, Christoph Kreutz, Thomas Mueller, Paul Mayer, Guenther Bonn, Thomas Gelbrich, Ulrich J. Griesser, Klaus Wurst, Volker Kahlenberg, Sven Nerdinger, Herwig Schottenberger
Summary: A novel series of N,N`-disubstituted azoimidazolium salts was synthesized based on a versatile late stage intermediate, and the derivatives obtained through various substitution reactions were found to have important applications in follow-up conversions. The compounds were characterized spectroscopically, and the formation of a neutral dimer chromophore was also observed.
Article
Chemistry, Organic
Josef Spreitz, Thomas Gelbrich, Sven Nerdinger, Marijan Stefinovic, Ulrich J. Griesser
Summary: An improved procedure for the preparation of naldemedine tosylate has been developed, allowing direct crystallization of pure polymorph form II from the reaction mixture. Solid state studies have revealed several additional new physical forms, whose crystal structures have been determined using single-crystal X-ray diffraction.
