基于紫精缺电子体及其化合物的设计合成、结构及变色与磁性研究

Viologen cations as a class of organic ligands have large conjugated molecular structure, excellent electron transfer characteristics, photochromic, electrochromic and thermochromic properties, which make them have been received considerable attention due to their potential applications in photochemistry, electrochemistry and materials chemistry. If such a photoelectric activity ion ligands are incorporated into organic polymers and metal organic frameworks, it will open up a new method for constructing some compunds with special optical and electrical properties. Furthermore, these compounds based on viologen cations along with light, heat and electricity reduction can become radicals, which is expected to bring new breakthroughs in the construction and regulation of molecular magnetic materials. At present, the study about the relationship between chromism and structure of viologen compounds is still relatively rare, especially the study about the magnetic changes before and after radical generation resulted from electron-transfer has not been reported. Based on the above, this project is aimed to (1) synthesis a series of viologen cationic ligands, especially bipyridinium based viologen ligands; (2) synthesis of some viologen coordination complexes, viologen supramolecular complexes and characterize their structures; (3) UV-vis, electrochemistry and EPR technology to characterize their thermochromic, photochromic and electrochromic properties; (4) magnetic measurements (MPMS and PPMS) to characterize the magnetic changes before and after chromism; (5) according to the above experimental results, summarizes the relationship between the structure and properties, research on the factors of rigidity/flexibility, the length of the conjugated system of ligand, different solvents, etc, on the structure and chromism, as well as magnetism. In short, this project aims to design and synthesize some advanced optical, electrical and magnetic chromism material with some potential applications.

紫精阳离子作为一类缺电子有机物，具有大共扼的分子结构、优良的电子转移特点、光热电致变色等性能，使其在光化学、电化学和材料化学领域拥有广泛的应用前景。将这种具有光电活性的阳离子引入到复合物和金属有机框架中，可为构筑具有特殊光电性能的化合物开辟一条新的道路。同时由于该类化合物伴随光热电还原可产生自由基，有望在分子磁性材料的构建及调控方面带来新的突破。目前有关紫精化合物的变色性能与结构之间的关系以及产生自由基前后化合物磁性的变化等研究还比较少见。基于此，本项目将设计合成鲜见研究报道的酰基紫精、刚性紫精及多羧酸紫精阳离子及其相关化合物，考察它们在固态和溶液中电子转移变色反应。重点研究紫精的刚性、柔性、不同的取代基、共轭链的长短以及溶剂、光电热效应和溶液的酸碱性等对化合物变色的影响及产生自由基前后磁性的变化。考察变色的可逆性，寻找颜色可调、磁性可控、可逆性好的新型变色多功能材料加以应用研究。

紫精阳离子作为一类缺电子有机物，具有大共扼的分子结构、优良的电子转移特点、光热电致变色等性能，使其在光化学、电化学和材料化学领域拥有广泛的应用前景。将这种具有光电活性的阳离子引入到复合物和金属有机框架中，可为构筑具有特殊光电性能的化合物开辟一条新的道路。同时由于该类化合物伴随光热电还原可产生自由基，有望在分子磁性材料的构建及调控方面带来新的突破。目前有关紫精化合物的变色性能与结构之间的关系以及产生自由基前后化合物磁性的变化等研究还比较少见。基于此，本项目设计并合成了一系列紫精化合物，测定了约20个紫精化合物或其杂化盐的结构，考察它们在固态和溶液中电子转移变色反应。重点研究紫精的刚性、柔性、不同的取代基、共轭链的长短以及溶剂、光电热效应和溶液的酸碱性等对化合物变色的影响及产生自由基前后磁性的变化。考察变色的可逆性，寻找颜色可调、磁性可控、可逆性好的新型变色多功能材料加以应用研究（1）设计合了成鲜见研究报道的酰基紫精、刚性紫精及多羧酸紫精阳离子及其相关化合物，如苯乙酮系列紫精，乙烯基系列紫精，并噻唑系列紫精等，分别对这几个系列化合物进行了结构表征。（2）苯乙酮取代基由于其具有独特的烯醇式结构，因此具有独特的变色及荧光现象，分别系统的研究了溶剂显色、溶剂荧光、固体光致变色和固体荧光，并且通过DFT计算证明了其自由基显色机理。（3）本项目还利用此类紫精特有的性质，对其进行了传感方向的实用化探索。设计合成的这一系列紫精中都含有苯乙酮类取代基会对不同有机试剂同时具有变色与荧光响应，为此可以有目的的设计制造溶剂识别试纸。另外，该系列紫精具有对胺类等碱性气体响应、光致变色和热致变色等性质，已将其制备成可视化检测器件并具有良好的性能。在本篇报告中，我们只选取部分具有代表性的成果进行详细的阐述。