基于多酸和有机小分子的杂化荧光分子的设计、合成及其发光性能研究

The fluorescent properties of polyoxometalates mainly arise from the metal ions with their own fluorescence, which result in the limited kinds of polyoxometalates-based fluorescent compounds. Comparatively speaking, small organic molecules with excellent fluorescent properties exhibit rich diversity of molecular structures owing to their easy adjustment. However, these molecules are susceptible to “density quenching” in the solid state, and the devices made from them are easily to gather and crystallize, inducing that the lifetime of the devices decrease. Therefore, the problem how to exclude these unfavourable factors needs to be solved urgently in the research process of fluorescent materials.. Utilizing the coordination or protonation of the nitrogen- or oxygen-containing small organic molecules possessing excellent fluorescent properties, we aim to prepare novel polyoxometalate-small organic molecule composites with fixed stoichiometric ratio and excellent fluorescent properties through the reaction of organic molecule with polyoxometalates. Furthermore, we focus on exploring the interaction mechanisms between them. In addition, the fluorescent properties of polyoxometalate-small organic molecule materials will be studied in detail so that we can reveal the factors that affect the fluorescent properties of these materials, which have an important theoretical significance in designing and synthesizing novel fluorescent materials. Also, taking full advantages of the fascinating structural diversities and tunable properties of polyoxometalates, the obtained fluorescent materials would be optimized. In this way, it will not only largely enrich their varieties of polyoxometalates bearing benign fluorescent properties, but also make up for their own deficiencies of small organic molecules. But more interesting and important is that we may eventually get the desired polyoxometalate-small organic molecule fluorescent materials with application value and even widely practical future.

多酸的荧光性质主要源于本身具有荧光性质的金属离子，因而化合物种类有限；具有荧光性质的有机小分子因分子结构易于调变而种类繁多，但其在固态下易发生“浓度猝灭”现象，一般掺杂法制成的器件又容易聚集结晶，使器件寿命缩短。如何排除这些不利因素，是荧光材料研究中亟待解决的关键问题。. 本项目旨在通过具有优秀荧光性质的含氮、氧有机小分子的质子化或配位作用，与多酸阴离子结合，形成具有固定化学计量比的多酸-有机小分子结合的杂化分子，并探讨多酸和有机小分子之间的作用机制；通过研究杂化分子的荧光性质，揭示其荧光性质的影响因素，对新型荧光分子的设计与合成具有重要的理论意义；同时充分利用多酸阴离子种类繁多、易于调配的优点，优化所得荧光化合物，不仅可以丰富多酸荧光化合物的种类，弥补有机小分子自身荧光性的不足，更有望得到具有应用价值的荧光材料，具有广阔的应用前景。

荧光材料在多个领域具有重要应用，新型荧光化合物的设计与合成是探索、开发新型荧光材料的基础；因此，设计、合成具有优良荧光性质的化合物并探索其发光规律为本项目的研究目标。. 在基金的资助下，本项目以结构明确、组成可调，具有优良理化性质且在催化、材料等领域具有重要应用价值和应用前景的多酸为前驱体，从分子层次上设计、合成了五个系列50余种具有荧光性质的化合物，并对其荧光性质进行了系统的探索。为设计、合成性质更为优秀的多酸基杂化荧光化合物提供了实验支撑和理论支持。. 在项目实施过程中，我们选用具有荧光性质的稀土化合物及含氮或含氧有机分子，与{P2W19}、{As2W19}、{P2W15}、{P2W17}、{XM12}(X=P、Si、B，M=W、Mo)多酸前驱体反应，制备了50余种基于[α-PW11O39]7‒、[α2-P2W17O61]10‒、[As2W19O67(H2O)]14‒、[As3W30O113]27‒及饱和Keggin阴离子的荧光化合物。对所得化合物进行了系统表征和晶体结构测定，系统研究了化合物的发光性能。研究结果表明，有机分子能很好地吸收能量并敏化稀土金属离子的荧光发射；通过稀土金属离子的掺杂可以调变化合物的荧光发光。如基于[α-PW11O39]7‒阴离子的Tm3+/Dy3+掺杂杂化化合物，随着Dy3+掺杂比例的增加，Tm3+/Dy3+-POM的发光光色可实现从蓝光到白光、到黄光的切换；Eu3+/Tb3+/Tm3+三元稀土掺杂的杂化化合物，当Tm3+的掺杂比例为0.5时，随着Tb3+掺杂比例的增加，Eu/Tb/Tm-POM的荧光发光可实现从红光到橙色光到黄色光的转换，当增加Tm3+的掺杂比例，减少Eu3+和Tb3+的比例时，Eu/Tb/Tm-POM的荧光发光可实现从黄光到白光到蓝光的转换。上述成果丰富了多酸基荧光化合物的种类和立体化学，为该类化合物的进一步应用提供了理论支持。