Structure, characterization, solubility and stability of podophyllotoxin polymorphs

Gong, Ningbo; Yang, Dezhi; Jin, Guimin; Liu, Shucong; Du, Guanhua; Lü, Yang

doi:10.1016/j.molstruc.2019.05.048

Cited by 18 publications

(2 citation statements)

References 21 publications

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“…The relative orientation of molecules within a crystalline material ultimately plays an important role in the resulting physical properties and has significant implications for the performance of high-value solids such as pharmaceuticals. − In addition, an improved understanding of interactions prevailing between individual components can also help to develop effective synthetic strategies for cocrystallizations. , A key concept that has become very helpful for identifying frequently occurring molecular recognition events in the solid state is the “synthon”: “a structural unit within a supermolecule which can be formed and or assembled by known or conceivable synthetic operations involving intermolecular interactions” . In order to further transition this concept into versatile and reliable synthetic strategies, we need systematic structural studies on closely related compounds so that we directly connect functional groups and molecular structure to specific and predictable molecular recognition events in the solid state. − …”

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confidence: 99%

Mapping out the Relative Influence of Hydrogen and Halogen Bonds in Crystal Structures of a Family of Amide-Substituted Pyridines

Abeysekera

Day

Sinha

et al. 2020

Crystal Growth & Design

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The simultaneous use of hydrogen bonds and halogen bonds in crystal engineering strategies has previously been employed in order to generate new solid forms with applications in e.g. pharmaceutical and agrochemical industries. Unfortunately, it is not easy to predict how these will coexist or compete in systems where multiple structural outcomes are possible. To address this challenge, we have investigated the solid-state landscape of a family of amide-substituted pyridines, belonging to four series, N-(pyridin-2-yl)benzamides (Bz), N-(pyridin-2-yl)picolinamides (2Pyr), N-(pyridin-2-yl)nicotinamides (3Pyr) and N-(pyridin-2-yl)isonicotinamides (4Pyr), functionalized with three different halogen atoms (chlorine, bromine, and iodine). We analyzed crystal structures of 16 compounds and identified their primary intermolecular interactions. Within each series, the chlorinated and brominated compounds present the same primary hydrogen-bond interactions as shown by the nonhalogenated parent. The N-(pyridin-2-yl)benzamides assembled via NH···N(Py) synthons to form dimers, N-(pyridin-2-yl)picolinamides showed intramolecular N–H···N(Py) hydrogen bonding, and both N-(pyridin-2-yl)nicotinamides (3Pyr) and N-(pyridin-2-yl) isonicotinamides (4Pyr) assembled via NH···N(Py) synthons leading to the formation of chains or four-membered rings. In three out of the four series (Bz, 2Pyr, and 4Pyr) the chloro and bromo compounds were isostructural. Three out of the four iodinated compounds exhibited halogen bonds to a neighboring molecule. In two of these compounds, Bz-I and 2Pyr-I, the primary hydrogen bonding resembled that of the other members of the family, indicating that the interactions mediated via the iodine atom were complementary to rather than competitive with the hydrogen bonds. Two polymorphs of 4Pyr-I were found, and in both forms, a halogen bond was formed with the N(py) acceptor which was engaged in N–H···N hydrogen bonds in the other members of this family. Since iodine acted as a halogen-bond donor in four-fifths of the crystal structures of iodinated compounds, these results show that the solid-state assembly of analogues compounds capable of hydrogen bonding have a high likelihood of being altered even in the presence of a nonactivated iodine atom.

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confidence: 99%

Mapping out the Relative Influence of Hydrogen and Halogen Bonds in Crystal Structures of a Family of Amide-Substituted Pyridines

Abeysekera

Day

Sinha

et al. 2020

Crystal Growth & Design

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“…Only anhydrous NANA was used as the starting solid material. Approximately 100 g of the solvent was maintained at a certain temperature in the jacketed glass crystallization vessel (Gong et al, 2019). Anhydrous NANA was added gradually until no additional solid dissolved.…”

Section: Solubility Measurementmentioning

confidence: 99%

Solubilities and Transformations of Anhydrous and Hydrated Forms of <i>N</i>-Acetyl-D-Neuraminic Acid in Water–2-Propanol Solutions

Zhu

Yuan

Chen

et al. 2020

J. Chem. Eng. Japan

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2-Propanol is used in the industrial crystallization of N-acetyl-D-neuraminic acid (NANA) to reduce its solubility, thereby enhancing its recovery. This study investigates the solubility and transition of NANA in mixed water-2-propanol systems. The solubility of NANA was measured within the temperature range of 273-336 K using high-performance liquid chromatography (HPLC) to determine the equilibrium compositions of NANA in aqueous solutions containing 67.9, 57.2, 35.5, 19.0, 9.2, 2.6 and 0 mol% of 2-propanol. Powder X-ray di raction (PXRD), Fourier-transform infrared spectroscopy (FTIR), di erential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) were employed to investigate the crystalline states of NANA. Thermodynamic properties, such as the entropy and enthalpy of dissolution, were estimated by applying the Van't Ho equation to plotting the solubility data. The mechanism of transformation from the anhydrous to dihydrated form is interpreted by considering the change in the water activity (primarily determined by the percentage of water and 2-propanol) of the solution. The results demonstrate that the states of NANA dihydrate and anhydrous NANA in water-2-propanol mixtures depend on both the water activity and temperature. These conclusions can provide useful information for determining the crystallization parameters needed to obtain a desired anhydrous or hydrated phase.

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Solubility of Pharmaceutical Solids

Sharma,

Gao,

et al. 2023

Oral Bioavailability and Drug Delivery

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Structure, characterization, solubility and stability of podophyllotoxin polymorphs

Cited by 18 publications

References 21 publications

Mapping out the Relative Influence of Hydrogen and Halogen Bonds in Crystal Structures of a Family of Amide-Substituted Pyridines

Mapping out the Relative Influence of Hydrogen and Halogen Bonds in Crystal Structures of a Family of Amide-Substituted Pyridines

Solubilities and Transformations of Anhydrous and Hydrated Forms of <i>N</i>-Acetyl-D-Neuraminic Acid in Water–2-Propanol Solutions

Solubility of Pharmaceutical Solids

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