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Polymorphism refers to the existence of a drug substance in multiple crystalline forms, known as polymorphs. Recently, this term has been expanded to include solvates (forms containing a solvent), amorphous forms (non-crystalline forms), and desolvated solvates (forms from which the solvent has been removed).
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Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
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A new polymorph of physcion.

Henning Hopf1, Peter G Jones, Eva Goclik

  • 1Institute of Organic Chemistry, Technical University of Braunschweig, Germany.

Acta Crystallographica. Section C, Crystal Structure Communications
|August 2, 2012
PubMed
Summary
This summary is machine-generated.

A new polymorph of 7-methoxy-2-methyl-4,5-dihydroxyanthracene-9,10-dione was identified, crystallizing in a different space group (P2(1)/c) than the original polymorph (P2(1)2(1)2(1)). This structural study reveals insights into hydrogen bonding and molecular packing in crystalline organic compounds.

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Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
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Area of Science:

  • Crystallography
  • Organic Chemistry
  • Solid-State Chemistry

Background:

  • The crystal structure of 7-methoxy-2-methyl-4,5-dihydroxyanthracene-9,10-dione was previously reported in space group P2(1)2(1)2(1) (polymorph Io).
  • Polymorphism is crucial in determining the physical and chemical properties of organic compounds.

Purpose of the Study:

  • To characterize a new crystalline polymorph (Im) of 7-methoxy-2-methyl-4,5-dihydroxyanthracene-9,10-dione.
  • To compare the molecular structure and crystal packing of the new polymorph with the previously reported one.

Main Methods:

  • Single-crystal X-ray diffraction analysis was used to determine the crystal structure of the new polymorph.
  • Analysis of bond lengths and intermolecular interactions (hydrogen bonding) was performed.

Main Results:

  • The new polymorph (Im) crystallizes in the monoclinic space group P2(1)/c.
  • Both hydroxyl groups form intramolecular hydrogen bonds to quinone oxygen atoms, influencing C=O bond lengths.
  • The crystal packing in (Im) features molecular tapes linked by hydrogen bonds, differing from the crosslinked pattern in (Io).

Conclusions:

  • The study successfully identified and characterized a new polymorph of the title compound.
  • The findings highlight the role of intramolecular hydrogen bonding and crystal packing in influencing the solid-state structure of organic molecules.
  • Understanding polymorphism is essential for controlling material properties.