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https://www.readbyqxmd.com/read/29786921/room-temperature-ferroelectricity-in-an-organic-cocrystal
#1
Adam J Matzger, Ren A Wiscons, Nagula Rajesh Goud, Joshua T Damron
Ferroelectric materials exhibit switchable remanent polarization due to reversible symmetry breaking under an applied electric field. Previous research has leveraged temperature-induced neutral-ionic transitions in charge-transfer (CT) cocrystals to access ferroelectrics that operate through displacement of molecules under an applied field. However, displacive ferroelectric behavior is rare in organic CT cocrystals and achieving a Curie temperature (TC) above ambient has been elusive. Here a cocrystal between acenaphthene and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane is presented that shows switchable remanent polarization at room temperature (TC = 68°C)...
May 22, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29786712/cocrystals-of-a-1-2-4-thiadiazole-based-potent-neuroprotector-with-gallic-acid-solubility-thermodynamic-stability-relationships-and-formation-pathways
#2
Artem O Surov, Andrei V Churakov, Alexey N Proshin, Xia-Lin Dai, Tongbu Lu, German L Perlovich
Three distinct solid forms, namely anhydrous cocrystals with 2 : 1 and 1 : 1 drug/acid ratios ([TDZ : GA] (2 : 1), [TDZ : GA] (1 : 1)), and a hydrated one having 1 : 1 : 1 drug/acid/water stoichiometry ([TDZ : GA : H2O] (1 : 1 : 1)), have been formed by cocrystallization of the biologically active 1,2,4-thiadiazole derivative (TDZ) with gallic acid (GA). The thermodynamic stability relationships between the cocrystals were rationalized in terms of Gibbs energies of the formation reactions and further verified by performing a set of competitive and exchange mechanochemical reactions...
May 22, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29765601/survey-and-analysis-of-crystal-polymorphism-in-organic-structures
#3
Kortney Kersten, Ramanpreet Kaur, Adam Matzger
With the intention of producing the most comprehensive treatment of the prevalence of crystal polymorphism among structurally characterized materials, all polymorphic compounds flagged as such within the Cambridge Structural Database (CSD) are analysed and a list of crystallographically characterized organic polymorphic compounds is assembled. Classifying these structures into subclasses of anhydrates, salts, hydrates, non-hydrated solvates and cocrystals reveals that there are significant variations in polymorphism prevalence as a function of crystal type, a fact which has not previously been recognized in the literature...
March 1, 2018: IUCrJ
https://www.readbyqxmd.com/read/29765475/mechanochemistry-of-nucleosides-nucleotides-and-related-materials
#4
REVIEW
Olga Eguaogie, Joseph S Vyle, Patrick F Conlon, Manuela A Gîlea, Yipei Liang
The application of mechanical force to induce the formation and cleavage of covalent bonds is a rapidly developing field within organic chemistry which has particular value in reducing or eliminating solvent usage, enhancing reaction rates and also in enabling the preparation of products which are otherwise inaccessible under solution-phase conditions. Mechanochemistry has also found recent attention in materials chemistry and API formulation during which rearrangement of non-covalent interactions give rise to functional products...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29735650/p-ii-like-signaling-protein-sbtb-links-camp-sensing-with-cyanobacterial-inorganic-carbon-response
#5
Khaled A Selim, Florian Haase, Marcus D Hartmann, Martin Hagemann, Karl Forchhammer
Cyanobacteria are phototrophic prokaryotes that evolved oxygenic photosynthesis ∼2.7 billion y ago and are presently responsible for ∼10% of total global photosynthetic production. To cope with the evolutionary pressure of dropping ambient CO2 concentrations, they evolved a CO2 -concentrating mechanism (CCM) to augment intracellular inorganic carbon (Ci ) levels for efficient CO2 fixation. However, how cyanobacteria sense the fluctuation in Ci is poorly understood. Here we present biochemical, structural, and physiological insights into SbtB, a unique PII -like signaling protein, which provides new insights into Ci sensing...
May 7, 2018: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29733499/unravelling-correlation-between-charge-mobility-and-cocrystallization-in-rod-rod-block-copolymer-for-high-performance-field-effect-transistors
#6
Mingjing Zhu, Shuang Pan, Yue Wang, Ping Tang, Feng Qiu, Zhiqun Lin, Juan Peng
The ability to capitalize on the cocrystallization strategy involving two or more components aggregating into cocrystals renders the creation of materials and devices with markedly improved charge mobility. This, however, has yet to be largely explored in all-conjugated block copolymers (BCPs). Herein, we report on the first investigation into the correlation between cocrystals and charge mobility in a series of new all-conjugated BCPs, namely, poly(3-butylthiophene)-b-poly(3-hexylselenophene) (P3BT-b-P3HS) with varied P3BT/P3HS block ratios for high-performance field-effect transistors...
May 7, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29697258/acid%C3%A2-%C3%A2-%C3%A2-amide-supramolecular-synthon-in-cocrystals-from-spectroscopic-detection-to-property-engineering
#7
Subhankar Saha, Gautam R Desiraju
The acid•••amide dimer heterosynthon in cocrystals of aromatic acids and primary amides is identified by marker peaks in the IR spectra that are characteristic of individual N-H•••O and O-H•••O interactions and also of the extended synthon. The O-H•••O hydrogen bond is crucial to heterodimer formation in contrast to the N-H•••O bond. A combinatorial study, tuning the chemical nature of acid and amide functionalities, leads to 22 cocrystals out of 36 crystallization attempts. Four quadrants I-IV are defined based on acidity and basicity of the acid and amide components...
April 26, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29691337/identification-of-the-i38t-pa-substitution-as-a-resistance-marker-for-next-generation-influenza-virus-endonuclease-inhibitors
#8
Jeremy C Jones, Gyanendra Kumar, Subrata Barman, Isabel Najera, Stephen W White, Richard J Webby, Elena A Govorkova
The clinical severity and annual occurrence of influenza virus epidemics, combined with the availability of just a single class of antivirals to treat infections, underscores the urgent need to develop new anti-influenza drugs. The endonuclease activity within the viral acidic polymerase (PA) protein is an attractive target for drug discovery due to the critical role it plays in viral gene transcription. RO-7 is a next-generation PA endonuclease inhibitor of influenza A and B viruses, but its drug resistance potential is unknown...
April 24, 2018: MBio
https://www.readbyqxmd.com/read/29689511/thz-spectra-and-corresponding-vibrational-modes-of-dna-base-pair-cocrystals-and-polynucleotides
#9
Fang Wang, Dongbo Zhao, Hao Dong, Ling Jiang, Lin Huang, Yunfei Liu, Shuhua Li
The generalized energy-based fragmentation (GEBF) approach has been applied to study the THz spectra and vibrational modes of base pair cocrystals under periodic boundary conditions (denoted as PBC-GEBF). Results of vibrational mode reveal that hydrogen bonds play a pivotal role in the pairing process of base crystals, where most NH and CH bonds stretch to some extent. We also found that hydrogen bonds of a self-made A:T cocrystal completely break in a transition from liquid to the solid state, while self-made C:G cocrystal is different and easier to form a cocrystal, as confirmed by X-ray diffraction (XRD) and terahertz (THz) spectra...
April 15, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29680958/intermolecular-interaction-as-a-direct-measure-of-water-solubility-advantage-of-meloxicam-cocrystalized-with-carboxylic-acids
#10
Piotr Cysewski
The solubility advantage (SA) of meloxicam cocrystalized with mono- and dicarboxylic acids was expressed in terms of equilibrium constants involving active pharmaceutical ingredient and coformer in aqueous solutions. It is argued that SA can be quantified by concentration of pairs formed in water. The pH and concentration of dissolved components is included explicitly in the model. The alternative behavior of mono- and dicarboxylic acids was emphasized and addressed to different structural motifs. The structural and energetic properties of meloxicam and its complexes with carboxylic acids were characterized, including tautmerism and dissociation in aqueous media...
April 21, 2018: Journal of Molecular Modeling
https://www.readbyqxmd.com/read/29678263/mid-infrared-spectroscopy-of-pharmaceutical-solids
#11
Harry G Brittain
It is now well established that infrared absorption spectroscopy is a powerful technique for the physical characterization of pharmaceutical solids. Besides being a preferred methodology for identification purposes, one can use trends in the energy values in the spectra as a means to study the solid-state properties of the system. FTIR spectra are often used to evaluate the type of polymorphism existing in a drug substance, can be very useful in studies of the water contained within a hydrate species, and are emerging as a technique of choice for the study of cocrystal systems...
2018: Profiles of Drug Substances, Excipients, and related Methodology
https://www.readbyqxmd.com/read/29669810/structural-insights-into-the-mechanism-of-action-of-a-biparatopic-anti-her2-antibody
#12
Vaheh Oganesyan, Li Peng, Jared S Bee, John Li, Samuel R Perry, Frank Comer, Linda Xu, Kimberly Cook, Kannaki Senthil, Lori Clarke, Kim Rosenthal, Chanshou Gao, Melissa Damschroder, Herren Wu, William F Dall'Acqua
Pathways of human EGF receptors are activated upon ligand dependent or independent homo or heterodimerization and their subsequent transphosphorylation. Overexpression of these receptors positively correlates with transphosphorylation rates and increased tumor growth rates. MEDI4276, an anti human epidermal growth factor receptor 2 (HER2) biparatopic antibody drug conjugate, has two paratopes within each of antibody arms. One, 39S, is aiming at the HER2 site involved in receptor dimerization and the second, single chain fragment (scFv) mimicking trastuzumab...
April 18, 2018: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29659293/solid-state-characterization-and-relative-formation-enthalpies-to-evaluate-stability-of-cocrystals-of-an-anti-diabetic-drug
#13
Naga Kiran Duggirala, Heather L Frericks Schmidt, Zhaohui Lei, Michael J Zaworotko, Joseph F Krzyzaniak, Kapildev K Arora
The current study integrates formation enthalpy and traditional slurry experiments to quickly assess the physical stability of cocrystal drug substance candidates for their potential to support drug development. Cocrystals of an anti-diabetic drug (GKA) with nicotinamide (NMA), vanillic acid (VLA) and ethyl vanillin (EVL) were prepared and characterized by powder X-ray diffractometry (PXRD), spectroscopic, and thermal techniques. The formation enthalpies of the cocrystals, and their physical mixtures (GKA + coformer) were measured by the Differential Scanning Calorimetry (DSC) method reported by Zhang et al...
April 16, 2018: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/29658170/new-ordered-structure-of-amorphous-carbon-clusters-induced-by-fullerene-cubane-reactions
#14
Mingrun Du, Mingguang Yao, JiaJun Dong, Peng Ge, Qing Dong, Éva Kováts, Sándor Pekker, Shuanglong Chen, Ran Liu, Bo Liu, Tian Cui, Bertil Sundqvist, Bingbing Liu
As a new category of solids, crystalline materials constructed with amorphous building blocks expand the structure categorization of solids, for which designing such new structures and understanding the corresponding formation mechanisms are fundamentally important. Unlike previous reports, new amorphous carbon clusters constructed ordered carbon phases are found here by compressing C8 H8 /C60 cocrystals, in which the highly energetic cubane (C8 H8 ) exhibits unusual roles as to the structure formation and transformations under pressure...
April 15, 2018: Advanced Materials
https://www.readbyqxmd.com/read/29614273/powder-compression-properties-of-paracetamol-paracetamol-hydrochloride-paracetamol-cocrystals-and-coformers
#15
Ann-Sofie Persson, Hamzah Ahmed, Sitaram Velaga, Göran Alderborn
The objective was to study the relationship between crystal structure, particle deformation properties and tablet-forming ability for the monoclinic form of paracetamol (PRA), two cocrystals and a salt crystal of PRA in addition to two coformers (oxalic acid and 4,4'-bipyridine). Thus, the structure - property - performance relationship was investigated. Analytical powder compression was used for determination of effective plasticity, as inferred from the Heckel yield pressure and the Frenning parameter, and the elastic deformation was determined from in-die tablet elastic recovery...
March 31, 2018: Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/29595961/solvatomechanical-bending-of-organic-charge-transfer-cocrystal
#16
Yanqiu Sun, Yilong Lei, Huanli Dong, Yonggang Zhen, Wenping Hu
Traditionally, organic crystals are very delicate and easily broken, without flexibility. Here, we show a simple co-crystallization strategy can be utilized to construct luminescent three-component cocrystal: (perylene-TCNB)•2THF. The solvated cocrystal can transform to pristine perylene-TCNB reversibly by successive removal or inclusion of the solvent molecules of THF, leading unexpected giant mechanical bending. Similarly, 1,4-dioxane, an analogue of THF, can also be used to achieve the bending of perylene-TCNB...
March 29, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29590750/repurposing-a-library-of-human-cathepsin-l-ligands-identification-of-macrocyclic-lactams-as-potent-rhodesain-and-trypanosoma-brucei-inhibitors
#17
Maude Giroud, Uwe Dietzel, Lilli Anselm, David Banner, Andreas Kuglstatter, Jörg Benz, Jean-Baptiste Blanc, Delphine Gaufreteau, Haixia Liu, Xianfeng Lin, August Stich, Bernd Kuhn, Franz Schuler, Marcel Kaiser, Reto Brun, Tanja Schirmeister, Caroline Kisker, François Diederich, Wolfgang Haap
Rhodesain (RD) is a parasitic, human cathepsin L (hCatL) -like cysteine protease produced by Trypanosoma brucei (T. b.) species and a potential drug target for the treatment of human African trypanosomiasis (HAT). A library of hCatL inhibitors was screened, and macrocyclic lactams were identified as potent RD inhibitors (Ki < 10 nM), preventing the cell-growth of T. b. rhodesiense (IC50 < 400 nM). SARs addressing the S2 and S3 pockets of RD were established. Three cocrystal structures with RD revealed a non-covalent binding mode of this ligand class, due to oxidation of the catalytic Cys25 to a sulfenic acid (Cys-SOH) during crystallization...
March 29, 2018: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/29557714/piroxicam-cocrystals-with-phenolic-coformers-preparation-characterization-and-dissolution-properties
#18
Shahram Emami, Khosro Adibkia, Mohammad Barzegar-Jalali, Mohammadreza Siahi-Shadbad
This study explores the preparation and investigation of dissolution properties of piroxicam cocrystals. Differential scanning calorimetry (DSC) was used to determine the capability of resorcinol (RES), methylparaben (MPB), and vanillin (VAN) to form cocrystals with piroxicam (PRX). Generation of cocrystals was attempted by liquid assisted grinding and slurry methods. Cocrystals were characterized by thermal methods, powder X-ray diffraction, and Fourier-transform infrared spectroscopy. Apparent solubility, intrinsic dissolution rate (IDR), and powder dissolution profile of cocrystals were compared with anhydrous piroxicam, piroxicam monohydrate (PRXMH), and previously reported piroxicam-succinic acid cocrystal...
March 20, 2018: Pharmaceutical Development and Technology
https://www.readbyqxmd.com/read/29556732/theoretical-investigation-of-the-structures-and-properties-of-cl-20-dnb-cocrystal-and-associated-pbxs-by-molecular-dynamics-simulation
#19
Gui-Yun Hang, Wen-Li Yu, Tao Wang, Zhen Li
In this work, a CL-20/DNB cocrystal explosive model was established and six different kinds of fluoropolymers, i.e., PVDF, PCTFE, F2311 , F2312 , F2313 and F2314 were added into the (1 0 0), (0 1 0), (0 0 1) crystal orientations to obtain the corresponding polymer bonded explosives (PBXs). The influence of fluoropolymers on PBX properties (energetic property, stability and mechanical properties) was investigated and evaluated using molecular dynamics (MD) methods. The results reveal a decrease in engineering moduli, an increase in Cauchy pressure (i...
March 19, 2018: Journal of Molecular Modeling
https://www.readbyqxmd.com/read/29550709/experimental-and-dft-simulation-study-of-a-novel-felodipine-cocrystal-characterization-dissolving-properties-and-thermal-decomposition-kinetics
#20
Caiqin Yang, Wei Guo, Yulong Lin, Qianqian Lin, Jiaojiao Wang, Jing Wang, Yanli Zeng
In this study, a new cocrystal of felodipine (Fel) and glutaric acid (Glu) with a high dissolution rate was developed using the solvent ultrasonic method. The prepared cocrystal was characterized using X-ray powder diffraction, differential scanning calorimetry, thermogravimetric (TG) analysis, and infrared (IR) spectroscopy. To provide basic information about the optimization of pharmaceutical preparations of Fel-based cocrystals, this work investigated the thermal decomposition kinetics of the Fel-Glu cocrystal through non-isothermal thermogravimetry...
May 30, 2018: Journal of Pharmaceutical and Biomedical Analysis
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