Synthesis, X-Ray Structure Characterization And Antioxidant Activities Of Some Chalcone Derivatives Containing 2-Chlorothiophene Moiety

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Date
2021-03
Authors
Ng, Weng Zhun
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Universiti Sains Malaysia
Abstract
A total of twelve heterocyclic chalcone compounds (1a-1l) containing 2-chlorothiophene moieties were synthesized using Claisen Schmidt Condensation process and were crystallized by slow evaporation methods. The postulate structure of these heterocyclic chalcone compounds were elucidated by FT-IR and NMR spectral analyses, followed by single crystal X-ray diffraction technique. Besides, the antioxidant potential of all compounds was evaluated using four different types of antioxidant assay which include 2, 2-diphenyl-1-picrylhydrazyl (DPPH), ferrous ion chelating (FIC), nitric oxide (NO) and Hydrogen Peroxide (H2O2) radical scavenging assay. Nine compounds are crystallized in monoclinic space group with four compounds in P21/c, three compounds in P21/n and two compounds in Cc and Pc. Another, two compounds are crystallized in triclinic space group š‘ƒ1Ģ… and one in orthorhombic space group Pbca. All the chalcone molecules are constructed by two individual rings which are interconnected by a C=Cāˆ’C(=O)āˆ’C enone bridge and form a trans configuration with respect to the C=C double bond. The majority of the compounds is adopted to a nearly-planar conformation except compound (E)-1-(5-chlorothiophen-2-yl)-3-mesitylprop-2-en-1-one (1e) and (E)-3-(5'-bromo-[2,2'-bithiophen]-5-yl)-1-(5-chlorothiophen-2-yl)prop-2-en-1-one (1g). Two molecular structures, (E)-1-(5-chlorothiophen-2-yl)-3-(thiophen-2-yl)prop-2-en-1-one (1b) and (E)-1-(5-chlorothiophen-2-yl)-3-(4-(trifluoromethyl)phenyl)prop-2-en-1-one (1h) are disordered structure. All compounds exhibit both conventional and non-conventional hydrogen bonds except compounds (E)-1-(5-chlorothiophen-2-yl)-3-(4-(methylthio)phenyl)prop-2-en-1-one (1d) and (E)-1-(5-chlorothiophen-2-yl)-3-(4-(trifluoromethoxy)phenyl)prop-2-en-1-0one (1i). Based on the antioxidant inhibition results, it shows that compounds (E)-1-(5-chlorothiophen-2-yl)-3 (pyridin-2-yl)prop-2-en-1-one (1a) and (E)-1-(5-chlorothiophen-2-yl)-3-(4-(methylthio)phenyl)prop-2-en-1-one (1d) are active toward FIC assay. Meanwhile, compound (E)-1-(5-chlorothiophen-2-yl)-3-(4-(methylthio)phenyl)prop-2-en-1-one (1d) shows higher chelating power than the standard drugs (EDTA) in IC50 test.
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