Studies Of Some 3, 4-Dichlorophenacyl Esters Derivatives: Synthesis, Characterization, Crystal Structure Determination And Antioxidant Properties
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Date
2021-03
Authors
Sim, Ai Jia
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Publisher
Universiti Sains Malaysia
Abstract
In this research, a series of nineteen 3, 4-dichlorophenacyl esters 2(a−s) were synthesized and crystallized by using slow evaporation method. The crystal structures were characterized by FT-IR and NMR spectroscopic analyses and further determined by single crystal X-ray crystallography technique (except 2o and 2s). The molecular conformation and crystal packing of these compounds were studied crystallographically. Eight compounds crystallized in monoclinic P21/c or P21/n space group, seven in triclinic 𝑃1̅, whereas two in orthorhombic Pna21 and Pbca. In these compounds, the planar 3, 4-dichlorophenyl ring is connected by C(=O)—O—C—C(=O) connecting bridge to various planar substituted phenyl ring. Most of the connecting bridges adopted clinal conformation between two carbonyl groups, while the conformations between carbonyl and each phenyl rings are nearly planar or slightly twisted due to their steric repulsion effect within each moiety. In the crystal packing, C—H ··· O hydrogen bonds (conventional) are involved in all of the compounds except compound 2d which is only involved C–H···π interactions (non-conventional). The antioxidant activities of all newly synthesized compounds were assessed using 2, 2-diphenyl-1-picrylhydrazyl (DPPH), ferrous ion chelating (FIC) and hydrogen peroxide (H2O2) radical scavenging assays. Radical inhibition effects of phenacyl derivatives are related to the electron donating and accepting groups of the substituents at their attached benzene rings. Compounds 2s, 2p, 2j, 2h and 2b showed potential inhibitory effect towards the H2O2 radical scavenging assay.
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Physics