Crystal engineering in IUCrJ: from `the' crystal structure to `a' crystal structure

Desiraju, Gautam R.

doi:10.1107/s2052252521000993

Cited by 7 publications

(3 citation statements)

References 18 publications

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“…Hence, ETP polymorph-II may be preferred for higher solubility, faster dissolution rate, and high permeability. The phenomenon of drug polymorphism continues to fascinate − almost 200 years after the earliest observations of polymorphic forms …”

Section: Discussionmentioning

confidence: 99%

Entacapone Polymorphs: Crystal Structures, Dissolution, Permeability, and Stability

Bommaka

Mannava

Sunil

et al. 2021

Crystal Growth & Design

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Entacapone (ETP) is a catechol-O-methyltransferase (COMT) drug used to treat Parkinson’s disease. ETP is available in the marketplace under the brand name Comtan since 2010, and ETP form-I was first reported in a patent published in 2001. However, analysis of its X-ray crystal structures and stability relationship of ETP polymorphs and their dissolution and permeability profile have not yet been reported. We crystallized two new conformational polymorphs of ETP from a water and acetone mixture and studied the structural origin of polymorphism and their phase transformations, stability, equilibrium solubility, dissolution, and permeability properties. The ETP molecule adopts different conformations in the polymorphic structures with slight changes in carbonyl and nitrile group orientations. Thermal analysis suggests that form-III and form-IV are enantiotropically related to form-I, which is the thermodynamically stable form at ambient conditions. In contrast, form-II is monotropically related to form-I. Equilibrium solubility, dissolution, and permeability studies show that form-II persists in the slurry medium and dissolves faster with a high flux rate compared to the stable form-I in phosphate buffer solution at 37 ± 0.5 °C.

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Section: Discussionmentioning

confidence: 99%

Entacapone Polymorphs: Crystal Structures, Dissolution, Permeability, and Stability

Bommaka

Mannava

Sunil

et al. 2021

Crystal Growth & Design

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“…In a recent editorial, Desiraju remarked on the conceptual shift from the structure to a structure, the latter being a point in the crystal-engineering landscape of a small molecule (Desiraju, 2021). Notwithstanding some discussion regarding definitions (Jones & Ulrich, 2010;Ulrich & Pietzsch, 2015), protein crystal polymorphism is a well recognized phenomenon (Ebrahim et al, 2019;Gillespie et al, 2014;Lanza et al, 2019;Van Driessche et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Protein–macrocycle polymorphism: crystal form IV of the Ralstonia solanacearum lectin–sulfonato-calix[8]arene complex

Mockler

Ramberg

Crowley

2023

Acta Cryst Sect D Struct Biol

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Controlled protein assembly and crystallization is necessary as a means of generating diffraction-quality crystals as well as providing a basis for new types of biomaterials. Water-soluble calixarenes are useful mediators of protein crystallization. Recently, it was demonstrated that Ralstonia solanacearum lectin (RSL) co-crystallizes with anionic sulfonato-calix[8]arene (sclx8) in three space groups. Two of these co-crystals only grow at pH ≤ 4 where the protein is cationic, and the crystal packing is dominated by the calixarene. This paper describes a fourth RSL–sclx8 co-crystal, which was discovered while working with a cation-enriched mutant. Crystal form IV grows at high ionic strength in the pH range 5–6. While possessing some features in common with the previous forms, the new structure reveals alternative calixarene binding modes. The occurrence of C 2-symmetric assemblies, with the calixarene at special positions, appears to be an important result for framework fabrication. Questions arise regarding crystal screening and exhaustive searching for polymorphs.

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“…Traditionally, crystal structures are viewed as repeating patterns of atoms, molecules or ions arranged in a threedimensional lattice. However, a particularly powerful concept in crystal engineering is to instead view the same crystal structure as a rich structural landscape in which the position of a molecule in a single crystal is a data point on this landscape (Desiraju, 2021). Different crystallizing conditions can lead to the formation of different crystal structures, each with its own unique set of properties.…”

Section: Introductionmentioning

confidence: 99%

Development of a scalar-based geometric parameterization approach for the crystal structure landscape of dithienylethene-based crystalline solids

Mitchell,

Zhang,

Jerozal

et al. 2023

IUCrJ

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Dithienylethenes (DTEs) are a promising class of organic photoswitches that can be used to create crystalline solids with properties controlled by light. However, the ability of DTEs to adopt multiple conformations, only one of which is photoactive, complicates the rational design of these materials. Herein, the synthesis and structural characterization of 19 crystalline solids containing a single DTE molecule are described. A novel D–D analysis of the molecular geometries obtained from rotational potential energy surface calculations and the ensemble of experimental structures were used to construct a crystal landscape for DTE. Of the 19 crystal structures, 17 contained photoinactive DTE rotamers and only 2 were photoactive. These results highlight the challenges associated with the design of these materials. Overall, the D–D analysis described herein provides rapid, effective and intuitive means of linking the molecular structure to photoactivity that could be applied more broadly to afford a general strategy for producing photoactive diarylethene-based crystalline solids.

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Crystal engineering in IUCrJ: from `the' crystal structure to `a' crystal structure

Abstract: What is ‘structure’ in the context of a molecular solid?

Cited by 7 publications

References 18 publications

Entacapone Polymorphs: Crystal Structures, Dissolution, Permeability, and Stability

Entacapone Polymorphs: Crystal Structures, Dissolution, Permeability, and Stability

Protein–macrocycle polymorphism: crystal form IV of the Ralstonia solanacearum lectin–sulfonato-calix[8]arene complex

Development of a scalar-based geometric parameterization approach for the crystal structure landscape of dithienylethene-based crystalline solids

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