Mandal Pubali, Manna Jhimli Sarkar, Das Debmallya, Mitra Manoj Kumar
School of Materials Science & Nanotechnology, Jadavpur University, Kolkata 700032, India.
Photochem Photobiol Sci. 2015 Apr;14(4):786-91. doi: 10.1039/c4pp00305e.
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.
仿生光捕获结构已被提议作为现有太阳能转换系统的替代方案。这一事实促使我们通过时间相关单光子计数（TCSPC）和荧光各向异性测量，成功实现了壳聚糖水凝胶基质中通过激子耦合叶绿素-a（Chl-a）分子的非相干电子跳跃[跳跃速率4.28 ns⁻¹]。紫外可见光谱表明，Chl-a分子在水凝胶基质中可保持稳定长达3个月。平面排列的Chl-a大环在23°时具有78皮秒时间尺度的单指数衰减参数、高初始各向异性数据[r0 = 0.33]以及缩短的TCSPC寿命[1.311 ns]，这表明跳跃激子级联在叶绿素分子中很突出。从拉曼光谱可以推测，由于通过卟啉大环中心Mg的第六配位，它们在壳聚糖水凝胶中通过水分子形成了高度配位的紧密堆积结构。所有这些数据预测，这种叶绿素-壳聚糖水凝胶可以成为人工光捕获系统中的活性成分。
