Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, Dr. Homi Bhabha Road, Pashan, Pune 411008, India.
Raman Research Institute, C. V. Raman Avenue, Bengaluru 560080, India.
J Phys Chem Lett. 2021 Mar 18;12(10):2651-2659. doi: 10.1021/acs.jpclett.1c00207. Epub 2021 Mar 10.
A molecular-level description of the aqueous nanochannels in lyotropic liquid crystals (LLCs) is crucial for their widespread utilization in diverse fields. Herein, the polarity and hydrogen bonding effects of LLC water molecules have been simultaneously explored using a single probe, 4'-N,N-dimethylamino-3-hydroxyflavone (DMA3HF), by the unique multiparametric sensitivity of the excited state proton-coupled electron transfer (PCET) phenomenon. The decreased ESIPT efficiency and the significantly retarded ESIPT dynamics (>20 times) of DMA3HF in the LLC phases suggests the dominant influence of strong hydrogen-bonded solute-solvent complexes that leads to a high activation barrier for ESIPT in the mesophases. The effects of hydrogen bonding on ESIPT have been elucidated by enhanced sampling techniques based on classical MD simulations of DMA3HF in explicit water. ESIPT via an extended hydrogen-bonded water wire is associated with a significantly high ESIPT activation barrier, substantiating the experimentally observed slow ESIPT dynamics inside the LLCs.
水相溶致液晶（LLC）中纳米通道的分子水平描述对于其在各个领域的广泛应用至关重要。在此，通过激发态质子耦合电子转移（PCET）现象的独特多参数灵敏度，使用单个探针 4'-N,N-二甲基氨基-3-羟基黄酮（DMA3HF）同时探索 LLC 水分子的极性和氢键效应。DMA3HF 在 LLC 相中的 ESIPT 效率降低和 ESIPT 动力学明显延迟（>20 倍）表明强氢键合的溶质-溶剂配合物的主导影响，导致介相中 ESIPT 的高活化能垒。氢键对 ESIPT 的影响已通过基于 DMA3HF 在显式水中的经典 MD 模拟的增强采样技术阐明。通过扩展的氢键水线进行的 ESIPT 与显着高的 ESIPT 活化能垒相关，证实了在 LLC 内部观察到的缓慢 ESIPT 动力学。
