Excitonic dynamics of Chlorophyll-a molecules in chitosan hydrogel scaffold

Biomimetic photo harvesting architecture has been proposed as an alternative for existing solar conversion systems. This fact led us to the successful realization of non-coherent electron hopping [hopping rate 4.28 ns −1 ] through excitonically coupled Chlorophyll-a (Chl-a) molecules within chitosan...

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Bibliographic Details
Published in:Photochemical & photobiological sciences 2015-04, Vol.14 (4), p.786-791
Main Authors: Mandal, Pubali, Manna, Jhimli Sarkar, Das, Debmallya, Mitra, Manoj Kumar
Format: Article
Language:English
Subjects:
Anisotropy
Biochemistry
Biomaterials
Chemistry
Chitosan - chemistry
Chlorophyll - chemistry
Chlorophyll - isolation & purification
Ethanol - chemistry
Fluorescence
Hydrogels - chemistry
Infrared Rays
Photochemical Processes
Physical Chemistry
Plant Leaves - chemistry
Plant Sciences
Solvents - chemistry
Spectrum Analysis
Spinacia oleracea - chemistry
Time Factors
Water - chemistry
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Summary:Biomimetic photo harvesting architecture has been proposed as an alternative for existing solar conversion systems. This fact led us to the successful realization of non-coherent electron hopping [hopping rate 4.28 ns −1 ] through excitonically coupled Chlorophyll-a (Chl-a) molecules within chitosan hydrogel matrix via TCSPC (Time Correlated Single Photon Count) and fluorescence anisotropy measurements. Chl-a molecules remain stable within the hydrogel matrix up to 3 months, as evidenced from UV-vis spectroscopy. The mono-exponential decay parameter with 78 picoseconds time scale, high initial anisotropy data [ r 0 = 0.33] and with reduced TCSPC lifetime [1.311 ns] of 23° in plane aligned Chl-a macrocycles, indicate that hopping excitonic cascade is prominent among chlorophyll molecules. From the Raman Spectra, it can be postulated that they form a highly co-ordinated closely packed structure via water molecules within chitosan hydrogel due to 6th co-ordination through central Mg of porphyrin macrocycle. All these data predict that this chlorophyll-chitosan hydrogel can be an active component in artificial light harvesting systems. Non-coherent energy hopping (hopping rate 4.28 ns −1 ) through excitonically coupled 23° aligned Chl-a molecules within chitosan hydrogel matrix, for an artificial light harvesting system.
ISSN:1474-905X
1474-9092
DOI:10.1039/c4pp00305e