Topological Influence of Lyotropic Liquid Crystalline Systems on Excited-State Proton Transfer Dynamics

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• 作者：Bibhisan Roy ; Sagar Satpathi ; Partha Hazra
• 刊名：Langmuir
• 出版年：2016
• 出版时间：March 29, 2016
• 年：2016
• 卷：32
• 期：12
• 页码：3057-3065
• 全文大小：505K
• ISSN：1520-5827

文摘

In the present work, we have investigated the excited-state proton transfer (ESPT) dynamics inside lipid-based reverse hexagonal (H_II), gyroid Ia3d, and diamond Pn3m LLC phases. Polarized light microscopy (PLM) and small-angle X-ray scattering (SAXS) techniques have been employed for the characterization of LLC systems. Time-resolved fluorescence results reveal the retarded ESPT dynamics inside liquid crystalline systems compared to bulk water, and it follows the order H_II < Ia3d < Pn3m < H₂O. The slower solvation, hampered “Grotthuss” proton transfer process, and most importantly, topological influence, of the LLC systems are believed to be mainly responsible for the slower and different extent of ESPT dynamics. Interestingly, recombination dynamics is found to be faster with respect to bulk water and it follows the order H₂O < Pn3m < Ia3d < H_II. Faster recombination dynamics arises due to lower dielectric constant and different channel diameters of these LLC systems. However, the dissociation dynamics is found to be slower than bulk water and it follows the order H_II < Ia3d < Pn3m < H₂O. Differences in critical packing parameter of LLC systems are believed to be the governing factors for the slower dissociation dynamics in these liquid crystalline systems.