COORDINATION STATE AND AGGREGATION PROCESS OF BACTERIOCHLOROPHYll A AND ITS DERIVATIVES: STUDY ON ACETONE-WATER AND METHANOL-WATER SOLVENTS Keadaan Koordinasi dan Proses Agregasi Pada Bakterioklorofil a Serta Turunannya
ABSTRACT Research on bacteriochlorophyll (BChl) a and its derivatives had been conducted to determine the coordination state and the aggregation process in acetone-water and methanol-water. The results showed that there were mainly two absorption peaks in BChl a and its derivatives, namely: Oxand Oy...
| المؤلف الرئيسي: | |
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| التنسيق: | مقال |
| منشور في: |
[Yogyakarta] : Universitas Gadjah Mada
2008
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| الموضوعات: |
| الملخص: | ABSTRACT
Research on bacteriochlorophyll (BChl) a and its derivatives had been conducted to determine the coordination
state and the aggregation process in acetone-water and methanol-water. The results showed that there were mainly
two absorption peaks in BChl a and its derivatives, namely: Oxand Oythat were very sensitive to coordination state
and aggregation process. The coordination state of pigment could be determined base" on Ox absorption peak that
wasinfluencedby solvents.In addition,the donornumber(DN)and taft parameters({3and TT*)from each sovents
could also be used to determine the coordination state. One or two of axial coordination toward center metal of BChl
a and its derivatives have to be filled by donor electron as a foreign nucleophile. Mg-BChl was exist as fivecoordinate
complexes in acetone but as six-coordinate complexes in methanol. Five-coordinate complexes of Zn-
BChl was occurred either in acetone or methanol. Cu-BChl was exist as four-coordinate complexes in acetone but
altered to five-coordinate complexes in methanol. The agregation process was influenced by the existence of water
added in pigment solution. The order of Mg-BChl a and its derivatives abilities to form new aggregate in acetonewater
and methanol-water, in regard of water-addition percentage was as follow: Cu-BChl > Zn-BChl > Mg-BChl.
Methanol was the solvent that could form aggregate of Mg-BChl and its derivatives at lower water-addition
percentage compared to acetone. |
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