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Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates
Published on: February 15, 2016
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Crystals of Benzamide, the First Polymorphous Molecular Compound, Are Helicoidal.
Alexander G Shtukenberg1, Ran Drori2, Elena V Sturm3
1Department of Chemistry and Molecular Design Institute, New York University, 100 Washington Square East, New York, NY, 10003, USA.
Angewandte Chemie (International Ed. in English)
|May 31, 2020
Summary
Spontaneously twisted crystals, like benzamide form II, form due to internal stress from lamellar overgrowth. This phenomenon, linked to polymorphism, explains unusual crystal shapes in crystallization.
Area of Science:
- Materials Science
- Crystallography
- Chemical Engineering
Background:
- Spontaneously twisted crystals are common but poorly understood.
- Benzamide (form II) is a metastable polymorph known since 1832.
- Polymorphism and crystal twisting often occur together, linked to high crystallization driving forces.
Purpose of the Study:
- To analyze the formation of twisted crystals of benzamide form II.
- To investigate the relationship between polymorphism, crystallization conditions, and crystal morphology.
- To elucidate the mechanism behind the observed non-classical crystal morphologies.
Main Methods:
- Crystallization from highly supersaturated aqueous and ethanol solutions.
- Optical and electron microscopy for structural analysis.
- Electron and powder X-ray diffraction for structural characterization.
Main Results:
- Benzamide form II crystals exhibit a complex lamellar structure.
- Internal stress generated by lamellar overgrowth was identified.
- This stress creates a twist moment, leading to observed non-classical morphologies.
Conclusions:
- Internal stress from lamellar overgrowth is the primary cause of spontaneous crystal twisting in benzamide form II.
- The study reveals a mechanism for non-classical crystal morphologies driven by crystallization dynamics.
- Understanding this phenomenon provides insights into crystal growth and polymorphism.
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