Polymorphic behavior of an organic compound

  • Nithya G vels university, Pallavaram,Chennai
  • Sudha R
  • Charles C Kanakam


Objective: Polymorphic crystals were exhibited in many organic compounds. The frequency changes, relative intensities, band contours, and numberof bands were observed in the spectra of different polymorphism which may be due to molecule-molecule interactions in the crystal unit cells. Theshape of a molecule at its site in the unit cell is distorted by molecular interactions.

Methods: The identification of a pure crystal form and to quantify a mixture of two forms infrared and Raman spectra of different crystalline formsof the same organic compound can be used. 2'-chloro-4-methoxy-3-nitro benzil (1) was synthesized and its two polymorphic forms were obtainedby recrystallization from the solvents acetone/chloroform and ethanol. The polymorphism present in the compound was confirmed by single crystalX-ray crystallography and differential scanning calorimetry.

Results: The polymorph 1.1 crystallizes as triclinic P-1 space group in the solvent acetone – chloroform and the polymorph 1.2 crystallizes asmonoclinic P21/c space group in the solvent ethanol.

Discussion: The intermolecular lattice energy and the interplay of molecular conformation in the crystallization and stability of polymorphs areidentified by X-ray crystal structures of conformational polymorphs.

Keywords: Conformational polymorphism, Organic compounds, Single crystal growth, X-ray diffraction.


1. Bernstein J. Polymorphism in Molecular Crystals. Oxford: Clarendon Press; 2002.
2. Hilfiker R. Polymorphism in the Pharmaceutical Industry. Weinheim: Wiley-VCH; 2006.
3. Dunitz JD, Bernstein J. Disappearing polymorphs. Acc Chem Res 1995;28:193.
4. Bond A. A post-Hartree–Fock study of pressure-induced phase transitions in solid nitrogen: The case of the α, γ, and ε low-pressure phases. Curr Opin Solid State Mater Sci 2009;13:91.
5. Grepioni F. Themed issue: Polymorphism and crystal forms. New J Chem 2008;32:1657.
6. Cong R, Zhu J, Wang Y, Yang T, Liao F, Jin C, Lin J. Can a small amount of crystal solvent be overlooked or have no structural effect? Isomorphous non-stoichiometric hydrates (pseudo-polymorphs): The case of salicylaldehyde thiosemicarbazone, Cryst Eng Comm, 2009, 11, 1971-1978.
7. Beheshti A, Clegg W, Filooria NE, Russo L. Protein/macromolecular crystallography. Acta Cryst C 2011;67:149-53.
8. Collas A, Zellerb M, Blockhuysa F. Phase equilibria diagrams PC database. Acta Cryst C 2011;67:171-4.
9. Steiner T. The hydrogen bond in the solid State. Angew Chem Int Ed Engl 2002;41:48-76.
10. (a) Jeffrey GA, Saenger W. Hydrogen Bonding in Biological Structures.Berlin: Springer-Verlag; 1991. (b) Jeffrey GA. An Introduction to Hydrogen Bonding. New York: Oxford University Press; 1997.
11. Desiraju GR. Hydrogen bridges in crystal engineering: Interactions without borders. Acc Chem Res 2002;35:565-73.
12. Desiraju GR, Steiner T. The Weak Hydrogen Bond in Structural Chemistry and Biology. UK: Oxford University; 1999.
13. Brock CP, Minton RP. Systematic effects of crystal packing forces: Biphenyl fragments with hydrogen atoms in all four ortho positions. J Am Chem Soc 1989;111(13):4586-93.
14. Perwitasari DA, Attobari J. Polymorphism of organic cation transporter 1 (oct1) in Indonesian cancer patients. Int J Pharm Pharm Sci 2014;6(5):380-2.
15. Meman AA, Ismail R, Musa N, Mohamad N, Ahmad AL. Simultaneous detection of multiple polymorphisms in CYP2B6 AND OPMR1 by nested PCR: A good approach for patients on methadone. Int J Pharm Pharm Sci 2014;6(3):215-22.
16. Hiltiker R editor. Polymorphism in the Pharmaceutical Industry. Weinheim, Germany: Wiley-VCH; 2006.
17. Brittain HG. Polymorphism and solvatomorphism 2005. J Pharm Sci 2007;96(4):705-28.
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How to Cite
G, N., S. R, and C. C. Kanakam. “Polymorphic Behavior of an Organic Compound”. Asian Journal of Pharmaceutical and Clinical Research, Vol. 10, no. 4, Apr. 2017, pp. 259-62, doi:10.22159/ajpcr.2017.v10i4.16702.
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