Preparation, structure and photostability of some metal complexes of anthraquinone extracted from Sudanese Senna

Abstract

Anthraquinone was extracted as sennidine from diffirent five sample of sudanese senna pods . The solubility test for sennidine was carried out using different solvents . sennidine was highly soluble in diethyl ether and dil HCL but insouble in water . sennidine percentage was determind using UV-VIS spectrophotoneter, it was varied from 3.1% to 6.9% , the higher sennidine percent was senna grow on farms. λ max of the extracted sennidine was found near 515 nm . Sennidine was identifying using I.R spectroscopy, different functional group of sennidine have shown bands on the I.R spectrum.. the extracted sennidine was used to prepare three complexes with three metal ions (Fe,Al and Cr) .The three complexes was insoluble in all solvents used for sennidine except dilute HCL . Absorbance and λ max for sennidine metal complexes were carried out using UV-VIS spectrophotometer λ max for Fe – sennidine was 250 nm, for Al –sennidine complex was 270 nm and for Cr –sennidine complex was 420 nm . the three complexes was identified using I.R spectroscopy, different functional group of sennidine- metal complexes have shown bands on the I.R spectrum . Metal legend ratio and stability constant (K) of the three complexes were studied using the modification of Job’s method . the ratio of the metal to the legend in all complexes was found to be 2:3 . log K3 for Al , Fe and Cr –sennidine were found to be 13.42 ,15.13 and 13.84 respectively. Photo stability of the three complexes was carried out and they found to be photo labile under sun light and aerobic conditions , the absorbance decreased after irradiation by sun light for 1, 2 and 3 hours for Fe and Al-sennidine complexes , while Cr –sennidine complex was found to be very sensitive towards light and the rate constant (k) was found using Kinetic method and it’s 0.324 hours -1 , 0.258 hours –1 and 27.58 hours -1 for Al, Fe and Cr.-sennidine complexes respectively.