(ISOLATION OF CHLOROPHYLL A FROM SPINACH LEAVES (AMARANTHUS SPEC DIV.) AND MODIFICATION OF CENTER ION WITH ZN2+ CATIONS: STUDY OF ITS POTENTIAL AS OPTICAL MATERIALS)

• Main Author: Nurhayati
• Format: Final Project
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/35301
• Institution: Institut Teknologi Bandung

Porphyrin is a natural pigment material that can absorb electromagnetic wave. This is due to its structure that has conjugated double bonds that allow the visible light to excite the electrons from the ground state to the excited states. One of the porphyrin derivative is chlorophyll, the pigment in the plant leaves that is responsible in photosynthesis. Mixture of chlorophyll a, b, carotene and other leaf pigments were extracted from spinach leaves (Amaranthus Spec div.) and then separated by chromatography using sucrose column method. Pure chlorophyll a which has a central magnesium ion is not stable against high intensity light exposure. It was observed that the pure chlorophyll a has a decay lifetime of 12.79 seconds that obtained from the fluorescence signal due to the irradiation with 405 nm violet laser that resonates with the Soret band. In order to be applied as optical material, the stability of chlorophyll a needs to be improved. One way to enhance the photostability of chlorophyll a is by changing the center ion, were in this study Mg2+ in chlorophyll a is replaced by Zn2+ to form Zn-pheophytin a. The results have shown a significant increase in decay lifetime from 12.79 to 49.48 seconds by introducing the Zn2+ ion into porphyrin ring in chlorophyll a. Characterizations of Zn-pheophytin a cover UV-Vis spectroscopy, fluorescence spectroscopy and mass spectroscopy. It observed that the absorption maximum of Soret band is red shifted from 413 nm to 424 nm after the introduction of Zn2+ into porphyrin ring, while the Q band maximum is blue shifted from 667 nm to 658 nm. Other evidence to ensure that Mg2+ ions have been replaced by Zn2+ is the mass spectroscopy results. Here, the results show the presence of m/z 933.5 and m/z 971.5 species, which are typical for Zn-pheophytin a and Zn-pheophytin a dihydrate.