纤维素聚集诱导室温磷光

Luminescent polymers containing unconventional chromophores (LPCUC) construed by nature matter has the advantages of easy synthesis, small cytotoxicity and good biocompatibility, has a wide application prospect in the field of biomimetic imaging. This project is based on the discovery that cellulose has room temperature phosphorescence emission properties. In order to tuning phosphorescence photophyscial properties (emission wavelength, emission efficiency, life time), this project intend to, first, the carbonyl group grafted into cellulose through etherification between hydroxyl groups of cellulose and the halogenated fatty acid, enhancement the orbital spin coupling, to control the emission color and improve the phosphorescence emission efficiency; Second, the restriction intramolecular rotations of cellulose, reduce the excited state of non-radiation transition, enhanced phosphorescence efficiency through chemical cross-linking reaction using esterification between the hydroxyl groups of cellulose and polycarboxylic   fatty acid ; Third, synthesized cellulose ionomer use the heavy atom effect of metal elements and the restriction intramolecular rotations of ion bond, synergistically improve the luminous efficiency and phosphorescence life time of cellulose. The effects of chemical structure and condensed structure on the photophysical properties of cellulose room temperature phosphorescence shall be studied. The technical problems in the poor luminous efficiency and difficulty tuning emission color of cellulose will besolved. The general molecular design principle of cellulose-based room temperature phosphorescence emission material shall be established based on the photoluminescence mechanism of cellulose. This project provides a theoretical basis for the study of luminescent polymers containing unconventional chromophoreswith room temperature phosphorescent emission properties, and will lay thefoundation for the development of cellulose functional materials.

利用天然产物构筑含非典型性生色团的发光材料，具有合成容易、细胞毒性小、生物相容性好等特点，在生物成像领域中有广阔的应用前景。本项目在发现纤维素具有室温磷光发射的基础上，拟通过：一、利用纤维素的羟基与卤代脂肪酸醚化反应接枝引入羰基，增强轨道自旋耦合，调控发光颜色，提高磷光发射效率；二、利用纤维素的羟基与多元脂肪酸酯化等反应对纤维素进行交联，限制分子内旋转，降低激发态的非辐射跃迁，增强磷光发射效率；三、利用金属元素的重原子效应和离子键对分子内旋转的限制构筑纤维素离聚物，协同提高纤维素的发光效率、调控磷光寿命。研究纤维素的化学结构、凝聚状态的变化对纤维素室温磷光光物理性质的影响，解决纤维素发光效率差、发光颜色难以调控的技术难点，阐明纤维素室温磷光的发光机理，初步建立基于纤维素室温磷光材料分子设计一般性原则。本项目为含非典型性生色团的室温磷光材料研究提供理论依据，为纤维素功能材料的开发奠定基础。

不含芳香性单元的非典型发光材料由于合成容易、细胞毒性小，生物相容性好等优点，使其在化学传感、生物成像等领域具有广阔的应用前景。本项目提出纤维素聚集诱导室温磷光的想法，在实验方面，研究了纤维素本征的磷光光学性质，考察了取代基对纤维素磷光性质的影响；采用廉价金属离子与纤维素衍生物形成的配位键和离子键增强了其磷光寿命和发光效率。在理论计算方面明确了羟基的里德堡激发会将电子激发到弥散的里德堡轨道上，产生有效的电子相互作用，使体系离域扩展，有效共轭长度增加，加之纤维素体系中存在着大量的氢键使其构象刚化，从而易于受激发光；另外纤维素的醇羟基具有较大的旋轨耦合常数，使得其能通过系间窜跃形成三重态激子实现磷光发射。最后深入挖掘发光纤维素在离子传感、细胞成像等领域中的应用价值。本项目的开展阐明了纤维素的发光机制，丰富了非典型发光材料的研究内容，为新型非典型发光材料的开发奠定了一定的实验基础和提供了理论依据。