Journal articles: 'Stoichiometric cocrystal'

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Mir, Niyaz A., Ritesh Dubey, and Gautam R. Desiraju. "Four- and five-component molecular solids: crystal engineering strategies based on structural inequivalence." IUCrJ 3, no. 2 (January 5, 2016): 96–101. http://dx.doi.org/10.1107/s2052252515023945.

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A synthetic strategy is described for the co-crystallization of four- and five-component molecular crystals, based on the fact that if any particular chemical constituent of a lower cocrystal is found in two different structural environments, these differences may be exploited to increase the number of components in the solid. 2-Methylresorcinol and tetramethylpyrazine are basic template molecules that allow for further supramolecular homologation. Ten stoichiometric quaternary cocrystals and one quintinary cocrystal with some solid solution character are reported. Cocrystals that do not lend themselves to such homologation are termed synthetic dead ends.

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Topić, Filip, and Tomislav Friščić. "No regioselectivity for the steroid α-face in cocrystallization of exemestane with aromatic cocrystal formers based on phenanthrene and pyrene." Canadian Journal of Chemistry 98, no. 7 (July 2020): 386–93. http://dx.doi.org/10.1139/cjc-2020-0073.

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The anti-cancer steroidal drug exemestane presents significantly different behavior in cocrystallization with arenes compared with the previously explored steroid progesterone. Mechanochemical and solution-based cocrystallization of exemestane with hydroxy derivatives of phenanthrene and pyrene leads to the formation of cocrystals exhibiting clear O–H···O type arene-steroid hydrogen bonds. So far, exemestane and 1-hydroxypyrene have been observed to form only one type of cocrystal, with the 1:1 stoichiometric ratio of the two components. However, there are two stoichiometric variations of the cocrystal of 9-hydroxyphenanthrene and exemestane, with the arene:steroid stoichiometric ratio of either 1:1 or 1:2. Importantly, although cocrystallization of progesterone with the same arene cocrystal formers was previously reported to take place regioselectively through α···π contacts between the α-face of the steroid and the π-electron surface of the arene, the herein explored cocrystals of exemestane reveal α···π and β···π contacts, as well as sidewise interactions involving the arene π-system and different edges of the steroid molecule. The loss of regioselectivity for the steroid α-face in cocrystallization with the two monohydroxylated arenes is tentatively explained by the highly positive electrostatic surface potential of the steroid β-face and a diminished number of C–H groups on the α-face of exemestane compared with progesterone.

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Dhibar, Manami, Santanu Chakraborty, Souvik Basak, Paramita Pattanayak, Tanmay Chatterjee, Balaram Ghosh, Mohamed Raafat, and Mohammed A. S. Abourehab. "Critical Analysis and Optimization of Stoichiometric Ratio of Drug-Coformer on Cocrystal Design: Molecular Docking, In Vitro and In Vivo Assessment." Pharmaceuticals 16, no. 2 (February 13, 2023): 284. http://dx.doi.org/10.3390/ph16020284.

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In this present research, an attempt has been made to address the influence of drug-coformer stoichiometric ratio on cocrystal design and its impact on improvement of solubility and dissolution, as well as bioavailability of poorly soluble telmisartan. The chemistry behind cocrystallization and the optimization of drug-coformer molar ratio were explored by the molecular docking approach, and theoretical were implemented practically to solve the solubility as well as bioavailability related issues of telmisartan. A new multicomponent solid form, i.e., cocrystal, was fabricated using different molar ratios of telmisartan and maleic acid, and characterized by SEM, DSC and XRD studies. The molecular docking study suggested that specific molar ratios of drug-coformer can successfully cluster with each other and form a specific geometry with favourable energy conformation to form cocrystals. Synthesized telmisartan-maleic acid cocrystals showed remarkable improvement in solubility and dissolution of telmisartan by 9.08-fold and 3.11-fold, respectively. A SEM study revealed the formation of cocrystals of telmisartan when treated with maleic acid. DSC and XRD studies also confirmed the conversion of crystalline telmisartan into its cocrystal state upon treating with maleic acid. Preclinical investigation revealed significant improvement in the efficacy of optimized cocrystals in terms of plasma drug concentration, indicating enhanced bioavailability through improved solubility as well as dissolution of telmisartan cocrystals. The present research concluded that molecular docking is an important path in selecting an appropriate stoichiometric ratio of telmisartan: maleic acid to form cocrystals and improve the solubility, dissolution, and bioavailability of poorly soluble telmisartan.

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Rajkumar, Madhu, and Gautam R. Desiraju. "Quaternary and quinary molecular solids based on structural inequivalence and combinatorial approaches: 2-nitroresorcinol and 4,6-dichlororesorcinol." IUCrJ 8, no. 2 (January 11, 2021): 178–85. http://dx.doi.org/10.1107/s2052252520016589.

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A synthetic strategy for the formation of stoichiometric quaternary and nonstoichiometric quinary solids is outlined. A series of 2-nitroresorcinol-based quaternary cocrystals were developed from binary precursors in two conceptual stages. In the first stage, ternary solids are synthesized based on the structural inequivalence at two recognition sites in the binary. In the second stage, the ternary is homologated into a stoichiometric quaternary based on the same concept. Any cocrystal without an inequivalence becomes a synthetic dead end. The combinatorial approach involves lower cocrystal systems with different structural environments and preferred synthon selection from a synthon library in solution. Such are the stepping stones for the isolation of higher cocrystals. In addition, a quaternary cocrystal of 4,6-dichlororesorcinol is described wherein an unusual synthon is observed with two resorcinol molecules in a closed loop with two different ditopic bases. The concept of the virtual synthon in binaries with respect to isolated ternaries is validated for the 4,6-dichlororesorcinol system. It is possible that only some binary systems are amenable to homologation into higher cocrystals. The reasons for this could have to do with the existence of preferred synthon modules, in other words, the critical components of the putative higher assembly that cannot be altered. Addition of the third and fourth component might be more flexible, and the choices of these components, possible from a larger pool of chemically related molecules.

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Panzade, Prabhakar, Priyanka Somani, and Pavan Rathi. "Nevirapine Pharmaceutical Cocrystal: Design, Development and Formulation." Drug Delivery Letters 9, no. 3 (August 20, 2019): 240–47. http://dx.doi.org/10.2174/2210303109666190411125857.

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Background and Objective: The top approach to deliver poorly soluble drugs is the use of a highly soluble form. The present study was conducted to enhance the solubility and dissolution of a poorly aqueous soluble drug nevirapine via a pharmaceutical cocrystal. Another objective of the study was to check the potential of the nevirapine cocrystal in the dosage form. Methods: A neat and liquid assisted grinding method was employed to prepare nevirapine cocrystals in a 1:1 and 1:2 stoichiometric ratio of drug:coformer by screening various coformers. The prepared cocrystals were preliminary investigated for melting point and saturation solubility. The selected cocrystal was further confirmed by Infrared Spectroscopy (IR), Differential Scanning Calorimetry (DSC), and Xray Powder Diffraction (XRPD). Further, the cocrystal was subjected to in vitro dissolution study and formulation development. Results: The cocrystal of Nevirapine (NVP) with Para-Amino Benzoic Acid (PABA) coformer prepared by neat grinding in 1:2 ratio exhibited greater solubility. The shifts in IR absorption bands, alterations in DSC thermogram, and distinct XRPD pattern showed the formation of the NVP-PABA cocrystal. Dissolution of NVP-PABA cocrystal enhanced by 38% in 0.1N HCl. Immediate release tablets of NVP-PABA cocrystal exhibited better drug release and less disintegration time. Conclusion: A remarkable increase in the solubility and dissolution of NVP was obtained through the cocrystal with PABA. The cocrystal also showed great potential in the dosage form which may provide future direction for other drugs.

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Tupe, Suraj Ankush, Shital Prabhakar Khandagale, and Amrapali B. Jadhav. "Pharmaceutical Cocrystals: An Emerging Approach to Modulate Physicochemical Properties of Active Pharmaceutical Ingredients." Journal of Drug Delivery and Therapeutics 13, no. 4 (April 15, 2023): 101–12. http://dx.doi.org/10.22270/jddt.v13i4.6016.

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Most of the Active Pharmaceutical Ingredients (APIs) are typically formulated and administered to patients in oral solid dosage forms due to ease of administration, patient compliance and cost effectiveness. Poor water solubility, low permeability and low bioavailability of APIs are major hurdles in development of oral solid dosage forms. In recent years, cocrystal development has evolved as a feasible approach for enhancing the solubility and bioavailability of poorly soluble drugs. Crystal engineering strategies have been asserted to enhance the likelihood of discovering new solid forms of an API. A pharmaceutical cocrystal is made up of two basic components, an API and a harmless material known as a coformer in stoichiometric ratio. Cocrystallization of an API with a pharmaceutically acceptable coformer can improve the physical characteristics of the API, such as solubility, hygroscopicity, and compaction behavior, without affecting the API's pharmacological efficacy. This review article offers a comprehensive overview of pharmaceutical cocrystals, their physiochemical characteristics, and methods of preparation, with an emphasis on cocrystal screening and cocrystal characterization. The review also included recent FDA and EMA guidance on pharmaceutical cocrystals as well as an outline of multidrug cocrystals. Keywords: Pharmaceutical co-crystals, crystal engineering, coformers, supramolecular synthons, Solubility

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Kimoto, Kouya, Mitsuo Yamamoto, Masatoshi Karashima, Miyuki Hohokabe, Junpei Takeda, Katsuhiko Yamamoto, and Yukihiro Ikeda. "Pharmaceutical Cocrystal Development of TAK-020 with Enhanced Oral Absorption." Crystals 10, no. 3 (March 18, 2020): 211. http://dx.doi.org/10.3390/cryst10030211.

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The objective of this study was to improve the solubility of poorly water-soluble drugs by pharmaceutical cocrystal engineering techniques and select the best pharmaceutical forms with high solubility and solubilized formulations for progress from the early discovery stage toward the clinical stage. Several pharmaceutical cocrystals of TAK-020, a Bruton tyrosine kinase inhibitor, were newly discovered in the screening based on the solid grinding method and the slurry method, considering thermodynamic factors that dominate cocrystal formation. TAK-020/gentisic acid cocrystal (TAK-020/GA CC) was selected based on a physicochemical property of enhanced dissolution rate. TAK-020/GA CC was proven to be a reliable cocrystal formation with a definitive stoichiometric ratio by a variety of analytical techniques—pKa calculation, solid-state nuclear magnetic resonance, and single X-ray structure analysis from the view of regulation. Furthermore, its absorption was remarkable and beyond those achieved in currently existing solubilized formulation techniques, such as nanocrystal, amorphous solid dispersion, and lipid-based formulation, in dog pharmacokinetic studies. TAK-020/GA CC was the best drug form, which might lead to good pharmacological effects with regard to enhanced absorption and development by physicochemical characterization. Through the trials of solid-state optimization from early drug discovery to pharmaceutical drug development, the cocrystals can be an effective option for achieving solubilization applicable in the pharmaceutical industry.

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Biscaia, Isabela Fanelli Barreto, Samantha Nascimento Gomes, Larissa Sakis Bernardi, and Paulo Renato Oliveira. "Obtaining Cocrystals by Reaction Crystallization Method: Pharmaceutical Applications." Pharmaceutics 13, no. 6 (June 17, 2021): 898. http://dx.doi.org/10.3390/pharmaceutics13060898.

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Cocrystals have gained attention in the pharmaceutical industry due to their ability to improve solubility, stability, in vitro dissolution rate, and bioavailability of poorly soluble drugs. Conceptually, cocrystals are multicomponent solids that contain two or more neutral molecules in stoichiometric amounts within the same crystal lattice. There are several techniques for obtaining cocrystals described in the literature; however, the focus of this article is the Reaction Crystallization Method (RCM). This method is based on the generation of a supersaturated solution with respect to the cocrystal, while this same solution is saturated or unsaturated with respect to the components of the cocrystal individually. The advantages of the RCM compared with other cocrystallization techniques include the ability to form cocrystals without crystallization of individual components, applicability to the development of in situ techniques for the screening of high quality cocrystals, possibility of large-scale production, and lower cost in both time and materials. An increasing number of scientific studies have demonstrated the use of RCM to synthesize cocrystals, mainly for drugs belonging to class II of the Biopharmaceutics Classification System. The promising results obtained by RCM have demonstrated the applicability of the method for obtaining pharmaceutical cocrystals that improve the biopharmaceutical characteristics of drugs.

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Najih, Yuli Ainun, Farizah Izazi, Siswandono Siswandono, and Bella Anggraini Putri. "STUDI IN SILICO PEMBENTUKAN KOKRISTAL MELOXICAM DENGAN BERBAGAI KOFORMER PERBANDINGAN (1 : 1)." Jurnal Ilmiah Ibnu Sina (JIIS): Ilmu Farmasi dan Kesehatan 8, no. 1 (March 31, 2023): 31–38. http://dx.doi.org/10.36387/jiis.v8i1.1086.

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Cocrystal is one form of modification in increasing the solubility of meloxicam which is included in Biopharmaceutics Classifications System (BCS) II. Cocrystal is a multicomponent system with a stoichiometric ratio between the active ingredient and the coformer which are bound in the crystals lattice to form hydrogen bonds. Design of new drugs can be done through an in silico program to optimize the parent compound before the synthesis of derivative compounds. This study aims to predict which coformers are most stable in the formation of crystals. Cocrystal formation is done by drawing a two-dimensional structure from meloxicam and coformer using ChemBioDraw Professional 16.0 software from CambridgeSoft®. The prediction will result in the amount of bond energy formed between meloxicam with coformer. The smaller the bond energy, the more stable the meaning of the bond. The smaller the bond energy formed, the more stable the bond is. Stable bonds have a high probability of forming cocrystals meloxicam. Hydrogen bonds occur between hydrogen atoms and other atoms that have high electronegativities such as O and N atoms which have lone pairs of electrons. This electronegativity difference makes H atoms tightly bound to O and N atoms so that the hydrogen bonds in the meloxicam cocrystal are tightly bound and stable. From the results of the study showed that the most stable coformer can form cocrystals with a small bond energy that can produce bonds with meloxicam, namely urea.

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Rodríguez-Ruiz, Christian, Pedro Montes-Tolentino, Jorge Guillermo Domínguez-Chávez, Hugo Morales-Rojas, Herbert Höpfl, and Dea Herrera-Ruiz. "Tailoring Chlorthalidone Aqueous Solubility by Cocrystallization: Stability and Dissolution Behavior of a Novel Chlorthalidone-Caffeine Cocrystal." Pharmaceutics 14, no. 2 (January 30, 2022): 334. http://dx.doi.org/10.3390/pharmaceutics14020334.

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A cocrystal of the antihypertensive drug chlorthalidone (CTD) with caffeine (CAF) was obtained (CTD-CAF) by the slurry method, for which a 2:1 stoichiometric ratio was found by powder and single-crystal X-ray diffraction analysis. Cocrystal CTD-CAF showed a supramolecular organization in which CAF molecules are embedded in channels of a 3D network of CTD molecules. The advantage of the cocrystal in comparison to CTD is reflected in a threefold solubility increase and in the dose/solubility ratios, which diminished from near-unit values for D0D to 0.29 for D0CC. Furthermore, dissolution experiments under non-sink conditions showed improved performance of CTD-CAF compared with pure CTD. Subsequent studies showed that CTD-CAF cocrystals transform to CTD form I where CTD precipitation inhibition could be achieved in the presence of pre-dissolved polymer HPMC 80–120 cPs, maintaining supersaturation drug concentrations for at least 180 min. Finally, dissolution experiments under sink conditions unveiled that the CTD-CAF cocrystal induced, in pH-independent manner, faster and more complete CTD dissolution when compared to commercial tablets of CTD. Due to the stability and dissolution behavior of the novel CTD-CAF cocrystal, it could be used to develop solid dosage forms using a lower CTD dose to obtain the same therapeutic response and fewer adverse effects.

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Patel, Diksha J., and Prashant K. Puranik. "Pharmaceutical Co-crystal : An Emerging Technique to enhance Physicochemical properties of drugs." International Journal of ChemTech Research 13, no. 3 (2020): 283–90. http://dx.doi.org/10.20902/ijctr.2019.130326.

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Major constraints in development of new product are poor aqueous solubility, stability and low oral bioavailability, low permeability. As majority of drugs marketed worldwide are administered by oral route and about 40% -50% of the new molecular entities were never invade into the market because of such biopharmaceutical issues.So issues related to poor physiochemical property of an active pharmaceutical ingredient (API) can be resolved using cocrystallization approach.Crystallization emerge as potential technique for enhancement of solubility of poorly aqueous soluble drugs also helps to improve physicochemical with preserving the pharmacological properties of the API . Cocrystals are solids that are crystalline single-phase materials composed of two or more different molecular and/or ionic compounds generally in a stoichiometric ratio which are neither solvates/hydrates nor simple salts. It is multicomponent system in which one component is API and another is called coformer. Coformer selection is the main challenging step during cocrystal synthesis , so various screening methods for the selection of coformers was explained . This article also summarizes differences between cocrystals with salts, solvates and hydrates along with the implications and limitations of cocrystals .It also provides a brief review on different methods of cocrystal formation and characterization techniuqes of cocrystals. Lastly this article highlights 85 synthetic and 14 herbal cocrystals along with its method of preparation and coformers used.

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Wicaksono, Yudi, Dwi Setyawan, and Siswandono Siswandono. "Formation of Ketoprofen-Malonic Acid Cocrystal by Solvent Evaporation Method." Indonesian Journal of Chemistry 17, no. 2 (July 31, 2017): 161. http://dx.doi.org/10.22146/ijc.24884.

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The purpose of this work was to explore the formation of ketoprofen-malonic acid cocrystal by solvent evaporation method. Early detection of cocrystal formation was conducted by hot stage microscopy and solid-liquid phase diagram. Cocrystal were prepared by solvent evaporation method by using isopropyl alcohol as solvent. Characterization of cocrystal was done by Powder X-Ray Diffractometry (PXRD), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared (FTIR) Spectroscopy and Scanning Electron Microscopy (SEM). The results of hot stage microscopic and solid-liquid phase diagram indicated formation of ketoprofen-malonic acid cocrystal. PXRD and DSC measurements showed stoichiometric ratio of cocrystal ketoprofen-malonic acid (2:1). The ketoprofen-malonic acid cocrystal had melting point at 86.2 °C and unique peaks of PXRD pattern at 2θ of 6.1°, 17.8°, 23.2° and 28.6°. FTIR spectra indicated the formation of cocrystal due to interaction of C=O ketone group of ketoprofen with MA molecule. SEM images show that ketoprofen-malonic acid cocrystal have multi-shaped particles with rough surfaces.

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Rajendrakumar, Satyasree, Anuja Surampudi Venkata Sai Durga, and Sridhar Balasubramanian. "Strategic synthon approach in obtaining cocrystals and cocrystal polymorphs of a high-Z′ system deferiprone – an anti-thalassemia drug." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 77, no. 6 (November 12, 2021): 946–64. http://dx.doi.org/10.1107/s205252062100980x.

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Compounds with more than one molecule in the crystallographic asymmetric unit (Z′ > 1) display a noticeably stronger propensity to form cocrystals. Deferiprone is an anti-thalassemia drug known to exhibit polymorphic behaviour. Previously, three polymorphs were reported out of which one of them exhibited Z′ > 1. In the present manuscript, a fourth polymorph of deferiprone was identified and it also possessed Z′ > 1. All the four polymorphs showed similar hydrogen bonding features and differed in crystal packing. The ability of deferiprone to crystallize as Z′ > 1 prompted us to investigate the hydrogen bonding and synthon variation upon cocrystallization of deferiprone with hydroxyl-group-containing coformers such as catechol, hydroquinone, phloroglucinol, resorcinol and pyrogallol. Crystallization attempts along with PXRD analysis aided in obtaining 11 new cocrystal structures which involve different stoichiometric cocrystals and some polymorphs. Synthon analysis, crystal packing as well as thermal behaviour were assessed and compared. The presence of multiple phases in each cocrystal system in its respective bulk powders was identified and quantified using PXRD and Rietveld analysis. Homosynthons were observed in three co-crystal systems, while a heterosynthon was observed in five systems. The combination of both homo- and heterosynthon was observed in three cocrystal systems. The phase transformation events were observed in most of the systems. In nine co-crystal systems, the melting points were observed intermediate between those of the API and the coformers.

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Wang, Hui, and Wei Jun Jin. "Cocrystal assembled by 1,4-diiodotetrafluorobenzene and phenothiazine based on C—I...π/N/S halogen bond and other assisting interactions." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 73, no. 2 (March 29, 2017): 210–16. http://dx.doi.org/10.1107/s2052520617002918.

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The halogen-bonded cocrystal of 1,4-diiodotetrafluorobenzene (1,4-DITFB) with the butterfly-shape non-planar heterocyclic compound phenothiazine (PHT) was successfully assembled by the conventional solution-based method. X-ray single-crystal diffraction analysis reveals a 3:2 stoichiometric ratio for the cocrystal (1,4-DITFB/PHT), and the cocrystal structure is constructedviaC—I...π, C—I...N and C—I...S halogen bonds as well as other assisting interactions (e.g.C—H...F/S hydrogen bond, C—H...H—C and C—F...F—C bonds). The small shift of the 1,4-DITFB vibrational band to lower frequencies in FT–IR and Raman spectroscopies provide evidence to confirm the existence of the halogen bond. In addition, the non-planarity of the PHT molecule in the cocrystal results in PHT emitting weak phosphorescence and relatively strong delayed fluorescence. Thus, a wide range of delayed fluorescence and weak phosphorescence could play a significant role in selecting a proper π-conjugated system to engineer functional cocrystal and luminescent materials by halogen bonds.

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Li, Zi, and Adam J. Matzger. "Influence of Coformer Stoichiometric Ratio on Pharmaceutical Cocrystal Dissolution: Three Cocrystals of Carbamazepine/4-Aminobenzoic Acid." Molecular Pharmaceutics 13, no. 3 (February 3, 2016): 990–95. http://dx.doi.org/10.1021/acs.molpharmaceut.5b00843.

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Avdeef, Alex. "Cocrystal solubility-pH and drug solubilization capacity of sodium dodecyl sulfate – mass action model for data analysis and simulation to improve design of experiments." ADMET and DMPK 6, no. 2 (June 16, 2018): 105–39. http://dx.doi.org/10.5599/admet.505.

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This review discusses the disposition of the anionic surfactant, sodium dodecyl sulfate (SDS; i.e., sodium lauryl sulfate), to solubilize sparingly-soluble drugs above the surfactant critical micelle concentration (CMC), as quantitated by the solubilization capacity (k). A compilation of 101 published SDS k values of mostly poorly-soluble drug molecules was used to develop a prediction model as a function of the drug’s intrinsic solubility, S0, and its calculated H-bond acceptor/donor potential. In almost all cases, the surfactant was found to solubilize the neutral form of the drug. Using the mass action model, the k values were converted to drug-micelle stoichiometric binding constants, Kn, corresponding to drug-micelle equilibria in drug-saturated solutions. An in-depth case study (data from published sources) considered the micellization reactions as a function of pH of a weak base, B, (pKa 3.58, S0 52 μg/mL), where at pH 1 the BH.SDS salt was predicted to precipitate both below and above the CMC. At low SDS concentrations, two drug salts were predicted to co-precipitate: BH.Cl and BH.SDS. Solubility products of both were determined from the analysis of the reported solubility-surfactant data. Above the CMC, in a rare example, the charged form of the drug (BH+) appeared to be strongly solubilized by the surfactant. The constant for that reaction was also determined. At pH 7, the reactions were simpler, as only the neutral form of the drug was solubilized, to a significantly lesser extent than at pH 1. Case studies also featured examples of solubilization of solids in the form of cocrystals. For many cocrystal systems studied in aqueous solution, the anticipated supersaturated state is not long-lasting, as the drug component precipitates to a thermodynamically stable form, thus lowering the amount of the active ingredient available for intestinal absorption. Use of surfactant can prevent this. A recently-described method for predicting the solubility product of cocrystals (coupled with predicted k values described here) allowed for simulations of solubility-pH speciation profiles of cocrystal systems in the presence of SDS. Well in advance of any actual measurements, these simulations can be used to probe conditions favorable to the design of cocrystal experiments where SDS stabilizes cocrystal suspensions against drug precipitation over a predicted range of pH values.

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Souza, Fayene Zeferino Ribeiro de, Amanda Cosmo de Almeida, Patr�cia Osorio Ferreira, Richard Perosa Fernandes, and Fl�vio Junior Caires. "Screening of coformers for quercetin cocrystals through mechanochemical methods." Ecl�tica Qu�mica Journal 47, no. 1 (January 1, 2022): 64–75. http://dx.doi.org/10.26850/1678-4618eqj.v47.1.2022.p64-75.

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Quercetin (QUE) is a nutraceutical compound that exhibits pharmacological properties such as antioxidant, cardioprotective, anti-ulcer, and anti-inflammatory effects. Although QUE is well-known for its benefits, its efficacy is limited due to low solubility. Thus, cocrystallization acts as an interesting approach to improve the solubility�among other properties�of this compound. In this work, cocrystallization screening was applied through neat grinding (NG) and liquid-assisted grinding (LAG), in which QUE and four cocrystal formers (benzamide,�picolinamide, isonicotinamide, and pyrazinoic acid) were tested. The precursors and QUE-coformer systems were characterized using thermoanalytical techniques (TG-DTA), X-ray powder diffraction (XRPD), and Fourier transform infrared (FTIR) spectroscopy. The results showed the formation of QUE cocrystals with picolinamide and isonicotinamide coformers in a 1:1 stoichiometric ratio. Furthermore, although coformers are isomers, spectroscopic and thermal data suggest that the supramolecular synthons involved in cocrystallization are different.

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Liu, Xiaojiao, Adam A. L. Michalchuk, Colin R. Pulham, and Elena V. Boldyreva. "An acetonitrile-solvated cocrystal of piroxicam and succinic acid with co-existing zwitterionic and non-ionized piroxicam molecules." Acta Crystallographica Section C Structural Chemistry 75, no. 1 (January 1, 2019): 29–37. http://dx.doi.org/10.1107/s2053229618016911.

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This work reports a new acetonitrile (ACN)-solvated cocrystal of piroxicam (PRX) and succinic acid (SA), 2C15H13N3O4S·0.5C4H6O4·C2H3N or PRX:SA:ACN (4:1:2), which adopts the triclinic space group P\overline{1}. The outcome of crystallization from ACN solution can be controlled by varying only the PRX:SA ratio, with a higher PRX:SA ratio in solution unexpectedly favouring a lower stoichiometric ratio in the solid product. In the new solvate, zwitterionic (Z) and non-ionized (NI) PRX molecules co-exist in the asymmetric unit. In contrast, the nonsolvated PRX–SA cocrystal contains only NI-type PRX molecules. The ACN molecule entrapped in PRX–SA·ACN does not form any hydrogen bonds with the surrounding molecules. In the solvated cocrystal, Z-type molecules form dimers linked by intermolecular N—H...O hydrogen bonds, whereas every pair of NI-type molecules is linked to SA via N—H...O and O—H...N hydrogen bonds. Thermogravimetry and differential scanning calorimetry suggest that thermal desolvation of the solvate sample occurs at 148 °C, and is followed by recrystallization, presumably of a multicomponent PRX–SA structure. Vibrational spectra (IR and Raman spectroscopy) of PRX–SA·ACN and PRX–SA are also used to demonstrate the ability of spectroscopic techniques to distinguish between NI- and Z-type PRX molecules in the solid state. Hence, vibrational spectroscopy can be used to distinguish the PRX–SA cocrystal and its ACN solvate.

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Hong, Chao, Yan Xie, Yashu Yao, Guowen Li, Xiurong Yuan, and Hongyi Shen. "A Novel Strategy for Pharmaceutical Cocrystal Generation Without Knowledge of Stoichiometric Ratio: Myricetin Cocrystals and a Ternary Phase Diagram." Pharmaceutical Research 32, no. 1 (June 18, 2014): 47–60. http://dx.doi.org/10.1007/s11095-014-1443-y.

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Zhou, Zhengzheng, Hok Man Chan, Herman H. Y. Sung, Henry H. Y. Tong, and Ying Zheng. "Identification of New Cocrystal Systems with Stoichiometric Diversity of Salicylic Acid Using Thermal Methods." Pharmaceutical Research 33, no. 4 (January 7, 2016): 1030–39. http://dx.doi.org/10.1007/s11095-015-1849-1.

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Zotova, Julija, Zaneta Wojnarowska, Brendan Twamley, and Lidia Tajber. "Formation of stoichiometric and non-stoichiometric ionic liquid and cocrystal multicomponent phases of lidocaine with azelaic acid by changing counterion ratios." Journal of Molecular Liquids 344 (December 2021): 117737. http://dx.doi.org/10.1016/j.molliq.2021.117737.

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Zotova, Julija, Zaneta Wojnarowska, Brendan Twamley, and Lidia Tajber. "Formation of stoichiometric and non-stoichiometric ionic liquid and cocrystal multicomponent phases of lidocaine with azelaic acid by changing counterion ratios." Journal of Molecular Liquids 344 (December 2021): 117737. http://dx.doi.org/10.1016/j.molliq.2021.117737.

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Hajjar, Christelle, Tamali Nag, Hashim Al Sayed, Jeffrey S. Ovens, and David L. Bryce. "Stoichiomorphic halogen-bonded cocrystals: a case study of 1,4-diiodotetrafluorobenzene and 3-nitropyridine." Canadian Journal of Chemistry 100, no. 4 (April 2022): 245–51. http://dx.doi.org/10.1139/cjc-2021-0245.

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The concept of variable stoichiometry cocrystallization is explored in halogen-bonded systems. Three novel cocrystals of 1,4-diiodotetrafluorobenzene and 3-nitropyridine with molar ratios of 1:1, 2:1, and 1:2, respectively, are prepared by slow evaporation methods. Single-crystal X-ray diffraction analysis reveals key differences between each of the nominally similar cocrystals. For instance, the 1:1 cocrystal crystallizes in the P21/n space group and features a single chemically and crystallographically unique halogen bond between iodine and the pyridyl nitrogen. The 2:1 cocrystal crystallizes in the [Formula: see text] space group and features a halogen bond between iodine and one of the nitro oxygens in addition to an iodine–nitrogen halogen bond. The 1:2 cocrystal crystallizes with a large unit cell (V = 9896 Å3) in the Cc space group and features 10 crystallographically distinct iodine-nitrogen halogen bonds. Powder X-ray diffraction experiments carried out on the 1:1 and 2:1 cocrystals confirm that gentle grinding does not alter the crystal forms. 1H → 13C and 19F → 13C cross-polarization magic angle spinning (CP/MAS) NMR experiments performed on powdered samples of the 1:1 and 2:1 cocrystals are used as spectral editing tools to select for either the halogen bond acceptor or donor, respectively. Carbon-13 chemical shifts in the cocrystals are shown to change only very subtly relative to pure solid 1,4-diiodotetrafluorobenzene, but the shift of the carbon directly bonded to iodine nevertheless increases, consistent with halogen bond formation (e.g., a shift of +1.6 ppm for the 2:1 cocrystal). This work contributes new examples to the field of variable stoichiometry cocrystal engineering with halogen bonds.

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Oh, Se Ye, Christopher W. Nickels, Felipe Garcia, William Jones, and Tomislav Friščić. "Switching between halogen- and hydrogen-bonding in stoichiometric variations of a cocrystal of a phosphine oxide." CrystEngComm 14, no. 19 (2012): 6110. http://dx.doi.org/10.1039/c2ce25653c.

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25

Durán-Palma, Melissa Hidekel, Sonia Sanet Mendoza-Barraza, Nancy Evelyn Magaña-Vergara, Francisco Javier Martínez-Martínez, and Juan Saulo González-González. "Crystal structure of pharmaceutical cocrystals of 2,6-diaminopyridine with piracetam and theophylline." Acta Crystallographica Section C Structural Chemistry 73, no. 10 (September 20, 2017): 767–72. http://dx.doi.org/10.1107/s205322961701230x.

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Pharmaceutical cocrystals are crystalline solids formed by an active pharmaceutical ingredient and a cocrystal former. The cocrystals 2,6-diaminopyridine (DAP)–piracetam [PIR; systematic name: 2-(2-oxopyrrolidin-1-yl)acetamide] (1/1), C5H7N3·C6H10N2O2, (I), and 2,6-diaminopyridine–theophylline (TEO; systematic name: 1,3-dimethyl-7H-purine-2,6-dione) (1/1), C5H7N3·C7H8N4O2, (II), were prepared by the solvent-assisted grinding method and were characterized by IR spectroscopy and powder X-ray diffraction. Cocrystal (I) crystallized in the orthorhombic space group Pbca and showed a 1:1 stoichiometry. The DAP and PIR molecules are linked by an N—H...O hydrogen-bond interaction. Self-assembly of PIR molecules forms a sheet of C(4) and C(7) chains. Cocrystal (II) crystallized in the monoclinic P21/c space group and also showed a 1:1 stoichiometry. The DAP and TEO molecules are connected by N—H...N and N—H...O hydrogen bonds, forming an R 2 2(9) heterosynthon. A bidimensional supramolecular array is formed by interlinked DAP–TEO tetramers, producing a two-dimensional sheet.

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26

Machado Cruz, Ricardo, Tereza Boleslavská, Josef Beránek, Eszter Tieger, Brendan Twamley, Maria Jose Santos-Martinez, Ondřej Dammer, and Lidia Tajber. "Identification and Pharmaceutical Characterization of a New Itraconazole Terephthalic Acid Cocrystal." Pharmaceutics 12, no. 8 (August 6, 2020): 741. http://dx.doi.org/10.3390/pharmaceutics12080741.

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The crystallization of poorly soluble drug molecules with an excipient into new solid phases called cocrystals has gained a considerable popularity in the pharmaceutical field. In this work, the cocrystal approach was explored for a very poorly water soluble antifungal active, itraconazole (ITR), which was, for the first time, successfully converted into this multicomponent solid using an aromatic coformer, terephthalic acid (TER). The new cocrystal was characterized in terms of its solid-state and structural properties, and a panel of pharmaceutical tests including wettability and dissolution were performed. Evidence of the cocrystal formation was obtained from liquid-assisted grinding, but not neat grinding. An efficient method of the ITR–TER cocrystal formation was ball milling. The stoichiometry of the ITR–TER phase was 2:1 and the structure was stabilized by H-bonds. When comparing ITR–TER with other cocrystals, the intrinsic dissolution rates and powder dissolution profiles correlated with the aqueous solubility of the coformers. The rank order of the dissolution rates of the active pharmaceutical ingredient (API) from the cocrystals was ITR–oxalic acid > ITR–succinic acid > ITR–TER. Additionally, the ITR–TER cocrystal was stable in aqueous conditions and did not transform to the parent drug. In summary, this work presents another cocrystal of ITR that might be of use in pharmaceutical formulations.

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T, Mamatha, Sama M, and Husna K. Qureshi. "Development and Evaluation of Mesalamine—Glutamine Cocrystal Tablets for Colon Specific Delivery." International Journal of Pharmaceutical Sciences and Nanotechnology 10, no. 5 (September 30, 2017): 3866–74. http://dx.doi.org/10.37285/ijpsn.2017.10.5.8.

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The objective of the work was to develop the co-crystal formulation of mesalamine with glutamine. It was done to enhance dissolution rate, solubility and physicochemical properties to be used in pharmaceutical composition (tablet) for colon targeting. Co-crystal preparation was carried out by liquid assisted grinding method using glutamine as a co-crystal former (1:1 stoichiometric ratio) and acetonitrile as a solvent giving maximum solubility and dissolution rate. The formation of the co-crystals was confirmed by Fourier Transform – Infra Red spectrometry, Differential Scanning Calorimetry and Powder X-Ray Diffraction. Pre-compression studies included measure-ment of bulk density, tapped density, angle of repose, Hausner’s ratio and compressibility index. The tablets were prepared by direct compression. Post compression parameters for uncoated tablets included hardness, size and thickness, friability and weight variation. Enteric-coated tablets were prepared by dip-coating process using Eudragit RSPO, Triethyl citrate and isopropyl alcohol mixture as coating solution. The coated tablets were further evaluated for disintegration and dissolution testing. All the results were found to be under specified limits. Finally, co-crystal tablets were compared with marketed formulation. In vitro dissolution rate of optimized mesalamine co-crystal tablet was comparatively higher than marketed formulation, which reflects improvement in solubility. Glutamine has good anti-inflammatory property. Formulation with glutamine as co-crystal added more efficacies to mesalamine for treatment in colon related inflammatory diseases. It was concluded that stable co-crystals of mesalamine -glutamine having better anti-inflammatory property, increased solubility and improved in vitro dissolution of mesalamine can be successfully prepared.

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28

Clark, Nathaniel E., Adam Katolik, Kenneth M. Roberts, Alexander B. Taylor, Stephen P. Holloway, Jonathan P. Schuermann, Eric J. Montemayor, et al. "Metal dependence and branched RNA cocrystal structures of the RNA lariat debranching enzyme Dbr1." Proceedings of the National Academy of Sciences 113, no. 51 (December 6, 2016): 14727–32. http://dx.doi.org/10.1073/pnas.1612729114.

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Intron lariats are circular, branched RNAs (bRNAs) produced during pre-mRNA splicing. Their unusual chemical and topological properties arise from branch-point nucleotides harboring vicinal 2′,5′- and 3′,5′-phosphodiester linkages. The 2′,5′-bonds must be hydrolyzed by the RNA debranching enzyme Dbr1 before spliced introns can be degraded or processed into small nucleolar RNA and microRNA derived from intronic RNA. Here, we measure the activity of Dbr1 fromEntamoeba histolyticaby using a synthetic, dark-quenched bRNA substrate that fluoresces upon hydrolysis. Purified enzyme contains nearly stoichiometric equivalents of Fe and Zn per polypeptide and demonstrates turnover rates of ∼3 s−1. Similar rates are observed when apo-Dbr1 is reconstituted with Fe(II)+Zn(II) under aerobic conditions. Under anaerobic conditions, a rate of ∼4.0 s−1is observed when apoenzyme is reconstituted with Fe(II). In contrast, apo-Dbr1 reconstituted with Mn(II) or Fe(II) under aerobic conditions is inactive. Diffraction data from crystals of purified enzyme using X-rays tuned to the Fe absorption edge show Fe partitions primarily to the β-pocket and Zn to the α-pocket. Structures of the catalytic mutant H91A in complex with 7-mer and 16-mer synthetic bRNAs reveal bona fide RNA branchpoints in the Dbr1 active site. A bridging hydroxide is in optimal position for nucleophilic attack of the scissile phosphate. The results clarify uncertainties regarding structure/function relationships in Dbr1 enzymes, and the fluorogenic probe permits high-throughput screening for inhibitors that may hold promise as treatments for retroviral infections and neurodegenerative disease.

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Trask, Andrew V., Jacco van de Streek, W. D. Samuel Motherwell, and William Jones. "Achieving Polymorphic and Stoichiometric Diversity in Cocrystal Formation: Importance of Solid-State Grinding, Powder X-ray Structure Determination, and Seeding." Crystal Growth & Design 5, no. 6 (November 2005): 2233–41. http://dx.doi.org/10.1021/cg0501682.

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Martinez, Valentina, Nikola Bedeković, Vladimir Stilinović, and Dominik Cinčić. "Tautomeric Equilibrium of an Asymmetric β-Diketone in Halogen-Bonded Cocrystals with Perfluorinated Iodobenzenes." Crystals 11, no. 6 (June 18, 2021): 699. http://dx.doi.org/10.3390/cryst11060699.

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In order to study the effect of halogen bond on tautomerism in β-diketones in the solid-state, we have prepared a series of cocrystals derived from an asymmetric β-diketone, benzoyl-4-pyridoylmethane (b4pm), as halogen bond acceptor and perfluorinated iodobenzenes: iodopentaflourobenzene (ipfb), 1,2-, 1,3- and 1,4-diiodotetraflorobenzene (12tfib, 13tfib and 14tfib) and 1,3,5-triiodo-2,4,6-trifluorobenzene (135titfb). All five cocrystals are assembled by I···N halogen bonds involving pyridyl nitrogen and iodoperfluorobenzene iodine resulting in 1:1 (four compounds) or 1:2 (one compound) cocrystal stoichiometry. Tautomer of b4pm in which hydrogen atom is adjacent to the pyridyl fragment was found to be more stable in vacuo than tautomer with a benzoyl hydroxyl group. This tautomer is also found to be dominant in the majority of crystal structures, somewhat more abundantly in crystal structures of cocrystals in which additional I···O halogen bond with the benzoyl oxygen has been established. Attempts have also been made to prepare an equivalent series of cocrystals using a closely related asymmetric β-diketone, benzoyl-3-pyridoylmethane (b3pm); however, all attempts were unsuccessful, which is attributed to more effective crystal packing of b3pm isomer compared to b4pm, which reduced the probability of cocrystal formation.

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Marquez, Jason, Egor Novikov, Sergei Rigin, Marina S. Fonari, Raúl Castañeda, Tatiana Kornilova, and Tatiana V. Timofeeva. "Exploiting Supramolecular Synthons in Cocrystals of Two Racetams with 4-Hydroxybenzoic Acid and 4-Hydroxybenzamide Coformers." Chemistry 5, no. 2 (May 8, 2023): 1089–100. http://dx.doi.org/10.3390/chemistry5020074.

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Structures of three cocrystals of nootropic racetams were studied. They included two cocrystals of phenylpiracetam (PPA) with 4-hydroxybenzoic acid (HBA) with different stoichiometries, PPA·HBA and PPA·2HBA, and cocrystal of 2-(4-phenyl-2-oxopyrrolidin-1-yl)-N’-isopropylideneacetohydrazide (PPAH) with 4-hydroxybenzamide (HBD), PPAH·HBD·(acetone solvate). X-ray study of the pure forms of PPA and PPAH was also carried out to identify variations of molecular synthons under the influence of conformers. The cocrystal structures revealed the diversity of supramolecular synthons namely, amide-amide, amide-acid, acid-acid, and hydroxyl-hydroxyl; however, very similar molecular chains were found in PPA and PPA·2HBA, and similar molecular dimers in PPAH and PPAH·HBD. In addition, conformational molecular diversity was observed as disorder in PPA·2HBA as it was observed earlier for rac-PPA that allows for the consideration that cocrystal as an example of partial solid solution. Quantum chemical calculations of PPA and PPAH conformers demonstrated that for most conformers, energy differences do not exceed 2 kcal/mol that suggests the influence of packing conditions (in this case R- and S-enantiomers intend to occupy the same molecular position in crystal) on molecular conformation.

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32

Nisar, Madiha, Lawrence W. Y. Wong, Herman H. Y. Sung, Richard K. Haynes, and Ian D. Williams. "Cocrystals of the antimalarial drug 11-azaartemisinin with three alkenoic acids of 1:1 or 2:1 stoichiometry." Acta Crystallographica Section C Structural Chemistry 74, no. 6 (May 24, 2018): 742–51. http://dx.doi.org/10.1107/s2053229618006320.

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The stoichiometry, X-ray structures and stability of four pharmaceutical cocrystals previously identified from liquid-assisted grinding (LAG) of 11-azaartemisinin (11-Aza; systematic name: 1,5,9-trimethyl-14,15,16-trioxa-11-azatetracyclo[10.3.1.04,13.08,13]hexadecan-10-one) with trans-cinnamic (Cin), maleic (Mal) and fumaric (Fum) acids are herein reported. trans-Cinnamic acid, a mono acid, forms 1:1 cocrystal 11-Aza:Cin (1, C15H23NO4·C9H8O2). Maleic acid forms both 1:1 cocrystal 11-Aza:Mal (2, C15H23NO4·C4H4O4), in which one COOH group is involved in self-catenation, and 2:1 cocrystal 11-Aza2:Mal (3, 2C15H23NO4·C4H4O4). Its isomer, fumaric acid, only affords 2:1 cocrystal 11-Aza2:Fum (4). All cocrystal formation appears driven by acid–lactam R 2 2(8) heterosynthons with short O—H...O=C hydrogen bonds [O...O = 2.56 (2) Å], augmented by weaker C=O...H—N contacts. Despite a better packing efficiency, cocrystal 3 is metastable with respect to 2, probably due to a higher conformational energy for the maleic acid molecule in its structure. In each case, the microcrystalline powders from LAG were useful in providing seeding for the single-crystal growth.

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33

Eshtiagh-Hosseini, H., H. Aghabozorg, M. Mirzaei, S. A. Beyramabadi, H. Eshghi, A. Morsali, A. Shokrollahi, and R. Aghaei. "Hydrothermal synthesis, experimental and theoretical characterization of a novel cocrystal compound in the 2:1 stoichiometric ratio containing 6-methyluracil and dipicolinic acid." Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 78, no. 5 (May 2011): 1392–96. http://dx.doi.org/10.1016/j.saa.2011.01.016.

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34

Gao, Jiaoyang, Huifei Zhai, Peng Hu, and Hui Jiang. "The Stoichiometry of TCNQ-Based Organic Charge-Transfer Cocrystals." Crystals 10, no. 11 (November 2, 2020): 993. http://dx.doi.org/10.3390/cryst10110993.

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Organic charge-transfer cocrystals (CTCs) have attracted significant research attention due to their wide range of potential applications in organic optoelectronic devices, organic magnetic devices, organic energy devices, pharmaceutical industry, etc. The physical properties of organic charge transfer cocrystals can be tuned not only by changing the donor and acceptor molecules, but also by varying the stoichiometry between the donor and the acceptor. However, the importance of the stoichiometry on tuning the properties of CTCs has still been underestimated. In this review, single-crystal growth methods of organic CTCs with different stoichiometries are first introduced, and their physical properties, including the degree of charge transfer, electrical conductivity, and field-effect mobility, are then discussed. Finally, a perspective of this research direction is provided to give the readers a general understanding of the concept.

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35

Ranjan, Subham, Ramesh Devarapalli, Sudeshna Kundu, Subhankar Saha, Shubham Deolka, Venu R. Vangala, and C. Malla Reddy. "Isomorphism: `molecular similarity to crystal structure similarity' in multicomponent forms of analgesic drugs tolfenamic and mefenamic acid." IUCrJ 7, no. 2 (January 7, 2020): 173–83. http://dx.doi.org/10.1107/s205225251901604x.

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The non-steroidal anti-inflammatory drugs mefenamic acid (MFA) and tolfenamic acid (TFA) have a close resemblance in their molecular scaffold, whereby a methyl group in MFA is substituted by a chloro group in TFA. The present study demonstrates the isomorphous nature of these compounds in a series of their multicomponent solids. Furthermore, the unique nature of MFA and TFA has been demonstrated while excavating their alternate solid forms in that, by varying the drug (MFA or TFA) to coformer [4-dimethylaminopyridine (DMAP)] stoichiometric ratio, both drugs have produced three different types of multicomponent crystals, viz. salt (1:1; API to coformer ratio), salt hydrate (1:1:1) and cocrystal salt (2:1). Interestingly, as anticipated from the close similarity of TFA and MFA structures, these multicomponent solids have shown an isomorphous relation. A thorough characterization and structural investigation of the new multicomponent forms of MFA and TFA revealed their similarity in terms of space group and structural packing with isomorphic nature among the pairs. Herein, the experimental results are generalized in a broader perspective for predictably identifying any possible new forms of comparable compounds by mapping their crystal structure landscapes. The utility of such an approach is evident from the identification of polymorph VI of TFA from hetero-seeding with isomorphous MFA form I from acetone–methanol (1:1) solution. That aside, a pseudopolymorph of TFA with dimethylformamide (DMF) was obtained, which also has some structural similarity to that of the solvate MFA:DMF. These new isostructural pairs are discussed in the context of solid form screening using structural landscape similarity.

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36

Hamilton, Darren G., Daniel E. Lynch, Karl A. Byriel, and Colin H. L. Kennard. "A Neutral Donor-Acceptor p-Stack: Solid-State Structures of 1 : 1 Pyromellitic Diimide-Dialkoxynaphthalene Cocrystals." Australian Journal of Chemistry 50, no. 5 (1997): 439. http://dx.doi.org/10.1071/c97033.

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Pyromellitic diimide forms orange-coloured cocrystals of 1 : 1 stoichiometry with dialkoxynaphthalene derivatives. The solid-state structures of two examples are presented. The cocrystal formed with 2,6-dimethoxynaphthalene presents vertical stacks of alternating π-rich and π-deficient subunits with the long axes of the respective components approximately parallel. Investigation of the packing in the cocrystal also reveals a stabilizing array of hydrogen bonds between the components of adjacent stacks. Cocrystallization with 1,5-[2-(2-hydroxyethoxy)ethoxy]naphthalene, a derivative bearing hydroxy terminated ethyleneoxy chains, gives rise to an altered structural arrangement. Alternating donor- acceptor stacks once again dominate the structure but adopt a geometry where the long axes of the constituents are essentially perpendicular. Hydrogen-bonding interactions result in the formation of continuous non-covalently linked columns of donor and acceptor subunits by linking the terminal hydroxy functions of the naphthalene component to the imide protons. The structural preferences revealed by these solid-state analyses indicate that these complexes are useful prototypes of more complex neutral supramolecular assemblies.

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37

Khurshid, Asma, Aamer Saeed, Tuncer Hökelek, Umama Taslim, Madiha Irfan, Saba Urooge Khan, Aneela Iqbal, and Hesham R. El-Seedi. "Experimental and Hirshfeld Surface Investigations for Unexpected Aminophenazone Cocrystal Formation under Thiourea Reaction Conditions via Possible Enamine Assisted Rearrangement." Crystals 12, no. 5 (April 25, 2022): 608. http://dx.doi.org/10.3390/cryst12050608.

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Considering the astounding biomedicine properties of pharmaceutically active drug, 4-aminophenazone, also known as 4-aminoantipyrine, the work reported in this manuscript details the formation of novel cocrystals of rearranged 4-aminophenazone and 4-nitro-N-(4-nitrobenzoyl) benzamide in 1:1 stoichiometry under employed conditions for thiourea synthesis by exploiting the use of its active amino component. However, detailed analysis via various characterization techniques such as FT-IR, nuclear magnetic resonance spectroscopy and single crystal XRD, for this unforeseen, but useful cocrystalline synthetic adduct (4 and 5) prompted us to delve into its mechanistic pathway under provided reaction conditions. The coformer 4-nitro-N-(4-nitrobenzoyl) benzamide originates via nucleophilic addition reaction following tetrahedral mechanism between para-nitro substituted benzoyl amide and its acid halide (1). While the enamine nucleophilic addition reaction by 4-aminophenazone on 4-nitrosubstituted aroyl isothiocyanates under reflux temperature suggests the emergence of rearranged counterpart of cocrystal named N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazole-4-carbonothioyl)-4-nitrobenzamide. Crystallographic studies reveal triclinic system P-1 space group for cocrystal (4 and 5) and depicts two different crystallographically independent molecules with prominent C–H···O and N–H···O hydrogen bonding effective for structure stabilization. Hirshfeld surface analysis also displays hydrogen bonding and van der Waals interactions as dominant interactions in crystal packing. Further insight into the cocrystal synthetic methodologies supported the occurrence of solution-based evaporation/cocrystallization methodology in our case during purification step, promoting the synthesis of this first-ever reported novel cocrystal of 4-aminophenazone with promising future application in medicinal industry.

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38

Khurshid, Asma, Aamer Saeed, Tuncer Hökelek, Umama Taslim, Madiha Irfan, Saba Urooge Khan, Aneela Iqbal, and Hesham R. El-Seedi. "Experimental and Hirshfeld Surface Investigations for Unexpected Aminophenazone Cocrystal Formation under Thiourea Reaction Conditions via Possible Enamine Assisted Rearrangement." Crystals 12, no. 5 (April 25, 2022): 608. http://dx.doi.org/10.3390/cryst12050608.

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Considering the astounding biomedicine properties of pharmaceutically active drug, 4-aminophenazone, also known as 4-aminoantipyrine, the work reported in this manuscript details the formation of novel cocrystals of rearranged 4-aminophenazone and 4-nitro-N-(4-nitrobenzoyl) benzamide in 1:1 stoichiometry under employed conditions for thiourea synthesis by exploiting the use of its active amino component. However, detailed analysis via various characterization techniques such as FT-IR, nuclear magnetic resonance spectroscopy and single crystal XRD, for this unforeseen, but useful cocrystalline synthetic adduct (4 and 5) prompted us to delve into its mechanistic pathway under provided reaction conditions. The coformer 4-nitro-N-(4-nitrobenzoyl) benzamide originates via nucleophilic addition reaction following tetrahedral mechanism between para-nitro substituted benzoyl amide and its acid halide (1). While the enamine nucleophilic addition reaction by 4-aminophenazone on 4-nitrosubstituted aroyl isothiocyanates under reflux temperature suggests the emergence of rearranged counterpart of cocrystal named N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazole-4-carbonothioyl)-4-nitrobenzamide. Crystallographic studies reveal triclinic system P-1 space group for cocrystal (4 and 5) and depicts two different crystallographically independent molecules with prominent C–H···O and N–H···O hydrogen bonding effective for structure stabilization. Hirshfeld surface analysis also displays hydrogen bonding and van der Waals interactions as dominant interactions in crystal packing. Further insight into the cocrystal synthetic methodologies supported the occurrence of solution-based evaporation/cocrystallization methodology in our case during purification step, promoting the synthesis of this first-ever reported novel cocrystal of 4-aminophenazone with promising future application in medicinal industry.

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39

Khurshid, Asma, Aamer Saeed, Tuncer Hökelek, Umama Taslim, Madiha Irfan, Saba Urooge Khan, Aneela Iqbal, and Hesham R. El-Seedi. "Experimental and Hirshfeld Surface Investigations for Unexpected Aminophenazone Cocrystal Formation under Thiourea Reaction Conditions via Possible Enamine Assisted Rearrangement." Crystals 12, no. 5 (April 25, 2022): 608. http://dx.doi.org/10.3390/cryst12050608.

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Considering the astounding biomedicine properties of pharmaceutically active drug, 4-aminophenazone, also known as 4-aminoantipyrine, the work reported in this manuscript details the formation of novel cocrystals of rearranged 4-aminophenazone and 4-nitro-N-(4-nitrobenzoyl) benzamide in 1:1 stoichiometry under employed conditions for thiourea synthesis by exploiting the use of its active amino component. However, detailed analysis via various characterization techniques such as FT-IR, nuclear magnetic resonance spectroscopy and single crystal XRD, for this unforeseen, but useful cocrystalline synthetic adduct (4 and 5) prompted us to delve into its mechanistic pathway under provided reaction conditions. The coformer 4-nitro-N-(4-nitrobenzoyl) benzamide originates via nucleophilic addition reaction following tetrahedral mechanism between para-nitro substituted benzoyl amide and its acid halide (1). While the enamine nucleophilic addition reaction by 4-aminophenazone on 4-nitrosubstituted aroyl isothiocyanates under reflux temperature suggests the emergence of rearranged counterpart of cocrystal named N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazole-4-carbonothioyl)-4-nitrobenzamide. Crystallographic studies reveal triclinic system P-1 space group for cocrystal (4 and 5) and depicts two different crystallographically independent molecules with prominent C–H···O and N–H···O hydrogen bonding effective for structure stabilization. Hirshfeld surface analysis also displays hydrogen bonding and van der Waals interactions as dominant interactions in crystal packing. Further insight into the cocrystal synthetic methodologies supported the occurrence of solution-based evaporation/cocrystallization methodology in our case during purification step, promoting the synthesis of this first-ever reported novel cocrystal of 4-aminophenazone with promising future application in medicinal industry.

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40

Peloquin, Andrew J., Srikar Alapati, Colin D. McMillen, Timothy W. Hanks, and William T. Pennington. "Polymorphism, Halogen Bonding, and Chalcogen Bonding in the Diiodine Adducts of 1,3- and 1,4-Dithiane." Molecules 26, no. 16 (August 17, 2021): 4985. http://dx.doi.org/10.3390/molecules26164985.

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Through variations in reaction solvent and stoichiometry, a series of S-diiodine adducts of 1,3- and 1,4-dithiane were isolated by direct reaction of the dithianes with molecular diiodine in solution. In the case of 1,3-dithiane, variations in reaction solvent yielded both the equatorial and the axial isomers of S-diiodo-1,3-dithiane, and their solution thermodynamics were further studied via DFT. Additionally, S,S’-bis(diiodo)-1,3-dithiane was also isolated. The 1:1 cocrystal, (1,4-dithiane)·(I2) was further isolated, as well as a new polymorph of S,S’-bis(diiodo)-1,4-dithiane. Each structure showed significant S···I halogen and chalcogen bonding interactions. Further, the product of the diiodine-promoted oxidative addition of acetone to 1,4-dithiane, as well as two new cocrystals of 1,4-dithiane-1,4-dioxide involving hydronium, bromide, and tribromide ions, was isolated.

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41

Saikia, Basanta, Debabrat Pathak, and Bipul Sarma. "Variable stoichiometry cocrystals: occurrence and significance." CrystEngComm 23, no. 26 (2021): 4583–606. http://dx.doi.org/10.1039/d1ce00451d.

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42

Jayasankar, Adivaraha, L. Sreenivas Reddy, Sarah J. Bethune, and Naír Rodríguez-Hornedo. "Role of Cocrystal and Solution Chemistry on the Formation and Stability of Cocrystals with Different Stoichiometry." Crystal Growth & Design 9, no. 2 (February 4, 2009): 889–97. http://dx.doi.org/10.1021/cg800632r.

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43

Čejka, Jan, and Martin Lenz. "Growing cocrystals by stoichiometric cosublimation." Acta Crystallographica Section A Foundations and Advances 71, a1 (August 23, 2015): s457. http://dx.doi.org/10.1107/s2053273315093274.

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44

Borodi, Gheorghe, Alexandru Turza, Oana Onija, and Attila Bende. "Succinic, fumaric, adipic and oxalic acid cocrystals of promethazine hydrochloride." Acta Crystallographica Section C Structural Chemistry 75, no. 2 (January 16, 2019): 107–19. http://dx.doi.org/10.1107/s2053229618017904.

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Novel cocrystals of promethazine hydrochloride [PTZ-Cl; systematic name: N,N-dimethyl-1-(10H-phenothiazin-10-yl)propan-2-aminium chloride] with succinic acid (PTZ-Cl-succinic, C17H21N2S+·Cl−·0.5C4H6O4), fumaric acid (PTZ-Cl-fumaric, C17H21N2S+·Cl−·0.5C4H4O4) and adipic acid (PTZ-Cl-adipic, C17H21N2S+·Cl−·0.5C6H10O4) were prepared by solvent drop grinding and slow evaporation from acetonitrile solution, along with two oxalic acid cocrystals which were prepared in tetrahydrofuran (the oxalic acid hemisolvate, PTZ-Cl-oxalic, C17H21N2S+·Cl−·0.5C2H2O4) and nitromethane (the hydrogen oxalate salt, PTZ-oxalic, C17H21N2S+·C2HO4 −). The crystal structures obtained by crystallization from tetrahydrofuran and acetonitrile include the Cl− ion in the lattice structures, while the Cl− ion is missing from the crystal structure obtained by crystallization from nitromethane (PTZ-oxalic). In order to explain the formation of the two types of supramolecular configurations with oxalic acid, the intermolecular interaction energies were calculated in the presence of the two solvents and the equilibrium configurations were determined using density functional theory (DFT). The cocrystals were studied by X-ray diffraction, IR spectroscopy and differential scanning calorimetry. Additionally, a stability test under special conditions and water solubility were also investigated. PTZ-Cl-succinic, PTZ-Cl-fumaric and PTZ-Cl-adipic crystallized having similar lattice parameter values, and showed a 2:1 PTZ-Cl to dicarboxylic acid stoichiometry. PTZ-Cl-oxalic crystallized in a 2:1 stoichiometric ratio, while the structure lacking the Cl atom belongs has a 1:1 stoichiometry. All the obtained crystals exhibit hydrogen bonds of the type PTZ...Cl...(dicarboxylic acid)...Cl...PTZ, except for PTZ-oxalic, which forms bifurcated bonds between the hydrogen oxalate and promethazinium ions, along with an infinite hydrogen-bonded chain between the hydrogen oxalate anions.

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Tumanova, Natalia, Nikolay Tumanov, Franziska Fischer, Fabrice Morelle, Voraksmy Ban, Koen Robeyns, Yaroslav Filinchuk, Johan Wouters, Franziska Emmerling, and Tom Leyssens. "Exploring polymorphism and stoichiometric diversity in naproxen/proline cocrystals." CrystEngComm 20, no. 45 (2018): 7308–21. http://dx.doi.org/10.1039/c8ce01338a.

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Setyawan, Dwi, Firdaus Rendra Adyaksa, Hanny Lystia Sari, Diajeng Putri Paramita, and Retno Sari. "Cocrystal formation of loratadine-succinic acid and its improved solubility." Journal of Basic and Clinical Physiology and Pharmacology 32, no. 4 (June 25, 2021): 623–30. http://dx.doi.org/10.1515/jbcpp-2020-0456.

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Abstract Objectives Loratadine belongs to Class II compound of biopharmaceutics classification system (BCS) due its low solubility and high membrane permeability. Cocrystal is a system of multicomponent crystalline that mostly employed to improve solubility. Succinic acid is one of common coformer in cocrystal modification. This research aims to investigate cocrystal formation between loratadine and succinic acid and its effect on solubility property of loratadine. Methods Cocrystal of loratadine-succinic acid was prepared by solution method using methanol as the solvent. Cocrystal formation was identified under observation of polarization microscope and analysis of the binary phase diagram. The cocrystal phase was characterized by differential thermal analysis (DTA), powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR), and scanning electron microscopy (SEM). Solubility study was conducted in phosphate-citrate buffer pH 7.0 ± 0.5 at 30 ± 0.5 °C. Results Loratadine is known to form cocrystal with succinic acid in 1:1 M ratio. Cocrystal phase has lower melting point at 110.9 °C. Powder diffractograms exhibited new diffraction peaks at 2θ of 5.28, 10.09, 12.06, 15.74, 21.89, and 28.59° for cocrystal phase. IR spectra showed that there was a shift in C=O and O–H vibration, indicating intermolecular hydrogen bond between loratadine and succinic acid. SEM microphotographs showed different morphology for cocrystal phase. Loratadine solubility in cocrystal phase was increased up to 2-fold compared to loratadine alone. Conclusions Cocrystal of loratadine and succinic acid is formed by stoichiometry of 1:1 via C=O and H–O interaction. Cocrystal phase shows different physicochemical properties and responding to those properties, it shows improved loratadine solubility as well.

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Mavračić, Juraj, Dominik Cinčić, and Branko Kaitner. "Halogen bonding ofN-bromosuccinimide by grinding." CrystEngComm 18, no. 19 (2016): 3343–46. http://dx.doi.org/10.1039/c6ce00638h.

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Two halogen bonded cocrystals ofN-bromosuccinimide and 4,4′-bipyridine, with stoichiometric ratios 1 : 1 and 2 : 1, have been synthesized and characterized. We present the first mechanochemical cocrystallization ofN-bromosuccinimide.

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Cruz, Silvia, Jairo Quiroga, José M. de la Torre, Justo Cobo, John N. Low, and Christopher Glidewell. "3-[5-(4-Bromophenyl)-1H-pyrazol-3-ylamino]-5,5-dimethylcyclohex-2-en-1-one–(Z)-3-(4-bromophenyl)-3-chloroacrylonitrile (2/1): a stoichiometric cocrystal of a reaction product with one of its early precursors." Acta Crystallographica Section C Crystal Structure Communications 62, no. 10 (September 12, 2006): o608—o611. http://dx.doi.org/10.1107/s0108270106033968.

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Fael, Hanan, Rafael Barbas, Rafel Prohens, Clara Ràfols, and Elisabet Fuguet. "Synthesis and Characterization of a New Norfloxacin/Resorcinol Cocrystal with Enhanced Solubility and Dissolution Profile." Pharmaceutics 14, no. 1 (December 27, 2021): 49. http://dx.doi.org/10.3390/pharmaceutics14010049.

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A new cocrystal of Norfloxacin, a poorly soluble fluoroquinolone antibiotic, has been synthetized by a solvent-mediated transformation experiment in toluene, using resorcinol as a coformer. The new cocrystal exists in both anhydrous and monohydrate forms with the same (1:1) Norfloxacin/resorcinol stoichiometry. The solubility of Norfloxacin and the hydrated cocrystal were determined by the shake-flask method. While Norfloxacin has a solubility of 0.32 ± 0.02 mg/mL, the cocrystal has a solubility of 2.64 ± 0.39 mg/mL, approximately 10-fold higher. The dissolution rate was tested at four biorelevant pH levels of the gastrointestinal tract: 2.0, 4.0, 5.5, and 7.4. In a first set of comparative tests, the dissolution rate of Norfloxacin and the cocrystal was determined separately at each pH value. Both solid forms showed the highest dissolution rate at pH 2.0, where Norfloxacin is totally protonated. Then, the dissolution rate decreases as pH increases. In a second set of experiments, the dissolution of the cocrystal was evaluated by a unique dissolution test, in which the pH dynamically changed from 2.0 to 7.4, stepping 30 min at each of the four biorelevant pH values. Results were quite different in this case, since dissolution at pH 2 affects the behavior of Norfloxacin at the rest of the pH values.

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Arhangelskis, Mihails, Filip Topić, Poppy Hindle, Ricky Tran, Andrew J. Morris, Dominik Cinčić, and Tomislav Friščić. "Mechanochemical reactions of cocrystals: comparing theory with experiment in the making and breaking of halogen bonds in the solid state." Chemical Communications 56, no. 59 (2020): 8293–96. http://dx.doi.org/10.1039/d0cc02935a.

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The interconversions of halogen-bonded cocrystals exhibiting three different stoichiometries were predicted by different types of dispersion-corrected density functional theory (DFT) calculations and predictions experimentally validated by mechanochemistry.

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Journal articles on the topic 'Stoichiometric cocrystal'

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