ISSN 2630-0583 (Print)

ISSN 2630-0656 (Online)

JCST

Journal of Current Science and Technology

http://jcst.rsu.ac.th

Journal of Current Science and Technology. Vol.9 No.2 , July - December 2019.

Concerted hydrogen bond and Hirshfeld surface analysis of Curcumin, Curcuma longa

Saifon A. Kohnhorst and Saowanit Saithong

Abstract

Curcumin (C21H20O6) crystals were obtained from attempts to cocrystallize curcumin with amino acid in mixed ethanol/methanol solvent.  The curcumin structure, solved and refined by single crystal X-ray diffraction, exists in the enol form.  Analysis of the electron density demonstrates nonstatistical disorder of the positions for the enol proton forming a strong hydrogen bond stabilizing the enol form within the curcumin molecule.  Analysis of the intermolecular packing of the molecules shows that the crystal structure is assembled via two strong supramolecular O-H×××O interactions with distances of 2.4696(19) - 3.028(2) Å and a weak C-H···O hydrogen bond, distance of 4.046(3) Å.  The hydrogen bond graph set notation was assigned R62 (36) pattern.  Hirshfeld surface analysis indicates that the curcumin crystal structure is stabilized by the weak hydrogen bonds.  Crystal Data: C21H20O6 (Mr = 368.37 Daltons: monoclinic, space group P2/n (No. 13), a = 12.6956(3) Å, b = 7.2093(2) Å, c = 19.9362(5) Å, β = 95.276(2)°, V = 1816.96(8) Å3, Z = 4.

Keywords: crystal structure,, curcuma longa, curcumin, curcuminoid, Hirshfeld surface analysis, hydrogen bond

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DOI: 10.14456/jcst.2019.8