基于离子液体的稀土发光有序分子聚集体的组装和性质研究

Design and preparation of soft rare-earth functional materials with tunable luminescent properties are of great importance both in theory and in application. Motivated by our rich experiences for assembling the organized molecular aggregates in ionic liquids and also the recently successful fabrication of lyotropic liquid crystals using rare-earth complexes, the proposed project here will be concentrated on the assembling of the ionic liquid-based uniform or hierarchical rare-earth organized molecular aggregates. The ionic liquids will be used here not only as the assembling solvents, but also as the coordination agents to the rare-earth ions. The main driving forces for the aggregate formation are mainly the non-covalent interactions including solvophobic and electrostatic attractions, hydrogen bonding, and coordination interaction. The softness nature of such lyotropic aggregates makes it convenient for their structure modulation. Through the synergetic assembling with other luminescent units which are aggregation responsive, the color tunable organized molecular aggregates might be constructed. Such ionic liquid-based soft rare-earth aggregates could not only avoid the luminescence quenching in traditional solvents, but also improve the photo-thermal stability of rare-earth complex. Benefiting from the dual structural tunabilities on both the aggregate and the ionic liquid, the distribution of the rare-earth complex in different aggregate phases or the molecular packing manner of ligand molecules might be easily controlled. The kinetically tuning of energy transfer between the ligands or the ligand to the rare-earth ion may become also convenient, which could optimize the luminescent properties of rare-earth materials. Therefore, a novel way to fabricate the soft rare-earth luminescent functional materials could be established. The obtained results should provide the valuable information on the design and preparation of new supramolecular functional materials.

设计与制备具有可控发光性能的稀土软功能材料具有重要的理论意义和应用价值。基于申请人在离子液体中组装有序分子聚集体的丰富经验，以及制备稀土配合物溶致液晶的初步尝试，本课题拟利用离子液体作稀土离子配体或组装溶剂，借助疏溶剂、氢键、静电、配位等各种非共价作用力，利用简易可控的自组装方式，构建均匀或分级的稀土溶致有序分子聚集体结构；并通过与其它聚集响应性发光基元协同组装，构建可控变色有序分子聚集体。这种基于离子液体的稀土软聚集体材料，不仅避免了通常水分子带来的猝灭效应，提高了稀土材料的光热稳定性；而且利用聚集体与离子液体结构的双可调控性，易于实现稀土配合物在聚集体不同相态的分布和配体分子排列方式的调控，便于动态调整配体间或配体与稀土离子间能量转移，优化稀土材料的发光性能，建立一种构建稀土发光软功能材料的新途径。本课题的研究，将对新型超分子功能材料的设计与构建提供有价值的信息。

离子液体和低共熔溶剂作为新型非水溶剂，是改善稀土软材料发光性能的潜在理想组装介质，这对新型超分子功能材料的设计与构建有重要的理论和实际意义。本课题率先提出了利用离子液体构建稀土发光有序聚集体的理念，借助疏溶剂、静电、金属配位、氢键和主客体包结等非共价相互作用及动态共价键，选取聚合物(P123和PEI)、咪唑型阳离子表面活性剂、响应性表面活性剂(C12DMAO和Myr)、季铵盐类Gemini表面活性剂、胆酸盐、核苷酸、以及修饰有金刚烷/偶氮苯的两亲分子等为有机构筑基元，选取不同稀土离子、稀土配合物、含稀土杂多酸盐、层状稀土氢氧化物及聚集诱导发光化合物等为发光中心，在水、离子液体和低共熔溶剂中，构建了各种具有动态调控、多色发光增强且结构不一的有序聚集体，包括稀土发光增强型溶致液晶与囊泡、具有刺激响应的多色发光软物质。利用小角X射线散射、偏光显微镜、红外光谱、核磁共振谱、荧光光谱、扫描或透射电镜、原子力显微镜、激光共聚焦显微镜以及分子模拟等表征技术，探索了各种内外因素对聚集体结构形成和稀土发光性能的影响。研究发现，离子液体非水介质的选择和聚集体基质对稀土发光基元的有序分散和有效束缚，能使其发光性能得到有效提升和改善。初步尝试将低共熔溶剂作为稀土发光有序聚集体的组装介质，得到了丰富的聚集体形态和改善的稀土发光性能。本研究所得结果对设计与制备具有可控发光性能的稀土软功能材料具有较大的参考价值。相关研究成果已发表SCI收录论文21篇，其中影响因子大于3.0 的论文16篇。