title: Excitonic dynamics of Chlorophyll-a molecules in chitosan hydrogel scaffold.
abstract: 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 [r0 = 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.
authors: School of Materials Science & Nanotechnology, Jadavpur University, Kolkata 700032, India. jhimlisarkar0@gmail.com.
authors: Pubali
authors: P
authors: Mandal
authors: Jhimli Sarkar
authors: JS
authors: Manna
authors: Debmallya
authors: D
authors: Das
authors: Manoj Kumar
authors: MK
authors: Mitra
mesh_terms: D016880:Anisotropy; D048271:Chitosan / Q000737:chemistry*; D002734:Chlorophyll / Q000737:chemistry* / Q000302:isolation & purification; D000077194:Chlorophyll A; D000431:Ethanol / Q000737:chemistry; D005453:Fluorescence; D020100:Hydrogels / Q000737:chemistry*; D007259:Infrared Rays; D055668:Photochemical Processes; D018515:Plant Leaves / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013057:Spectrum Analysis; D018724:Spinacia oleracea / Q000737:chemistry; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D020100:Hydrogels; D012997:Solvents; D014867:Water; D002734:Chlorophyll; D000431:Ethanol; D048271:Chitosan; D000077194:Chlorophyll A