Synthetic, Spectral and Antibacterial Studies of Co(III) and Mn(III) Metal Chelates of 2,5-Dihydroxy undecyl 1,4-Benzoquinone and its Azo Derivatives

Abstract

Embelin (2,5 dihydroxy undecyl 1,4-benzoquinone), an orange
pigment extracted from the berries of Embelia ribes. an Indian
medicinal shrub, is a well known bioactive compound. Antiinflamatory,
antibiotic and analgesic activities of embelin were reported.
Embelin, having two hydroxyl groups and ketonic oxygen atoms
could function as a better chelating agent Azo derivatives of
embelin, with their azo, hydroxyl and ketonic groups would possess
enhanced ligational properties. With this idea, an attempt has been
made to prepare Mn(III) and Co(III) complexes of embelin (EM),
3-(4'-azo-antipyrine)embelin (AAPE) and 3-(2'-hydroxyl phenylazo)
embelin (OAPE) and were characterised by elemental analysis,
molar conductance, magnetic susceptibility measurements, thermal
and various spectral studies. Chemical and spectral studies indicate
that embelin complexes of Mn(III) and Co(III) were polymeric in
nature. In Mn(III) and Co(lII) complexes, AAPE behaves as
neutral tridentate while OAPE acts as  monovalent tridentate having
O_h or D_4h geometry with composition [M(AAPE)X₃] and
[M(OAPE)X₂(H₂O)] where M = Co(III) and Mn(III) and X = Cl,
Br,  NO₃, OAc, ClO₄. Ligands and their few metal complexes were
screened for their antibacterial activity.