Crown-ether coordination compounds with unusual structural and optic properties (Crown I)

金属阳离子与冠醚的配位化学早已为人所知，并由此产生了大量的化合物。通常，选择阳离子和冠醚是为了使阳离子直径和开口直径很好地匹配。广泛的配位化学已经产生了一些引人注目的化合物，配位的高选择性甚至允许定量测定，这已经在分析化学和传感器技术中找到了他们的方式。如果阳离子配位，原则上是发光的，相应的冠醚配位化合物也可以发光，但到目前为止，这种发光很弱或只在低温下观察到。通过我们的初步工作，我们最近表明，相对于冠醚的环开孔直径太小的阳离子会导致不同的配位和结构化学（例如，18-crown-6中的Mn2+）。令人惊讶的是，这些化合物还可以表现出出色的荧光特性，包括接近100%的量子产率（室温下），非线性光学（NLO）特性，以及频率对分后的高效光致发光激发。基于这一意外发现，本项目旨在合成具有突出发光性能的新型冠醚配位化合物（如Pr3+， Eu2+/3+, Tb3+, Sm3+, Ho3+, Tm2+/3+），并了解其异常发光性能的背景。手性条件下的合成将专门用于制备具有NLO性质的对映体纯冠醚配位化合物，并开发一类新的NLO材料。除了发光化合物外，阳离子相对于冠醚开环直径过小的概念最终将转移到具有金属-金属键的化合物中，并导致新的簇化学。

The coordination chemistry of metal cations with crown ethers has long been known and has led to a large number of compounds. Typically, cations and crown ethers are chosen so that cation diameter and opening diameter are well matched. The extensive coordination chemistry has led to some spectacular compounds, and the high selectivity of coordination even allows quantitative determinations that have found their way into analytical chemistry and sensor technology. If cations are coordinated, which, in principle, exhibit luminescence, the corresponding crown-ether coordination compounds may also exhibit luminescence, but so far the luminescence has been weak or only observed at low temperatures.With our preliminary work, we have recently shown that cations that are too small with respect to the ring opening diameter of the crown ether lead to diverse coordination and structural chemistry (e.g., Mn2+ in 18-crown-6). Surprisingly, such compounds can also exhibit outstanding fluorescence properties, which include quantum yields close to 100% (at room temperature), nonlinear optical (NLO) properties, and efficient photoluminescence excitation after frequency bisection. Based on this unexpected discovery, this project aims to synthesize new crown-ether coordination compounds (e.g., with Pr3+, Eu2+/3+, Tb3+, Sm3+, Ho3+, Tm2+/3+) with outstanding luminescence properties and to understand the background of the unusual luminescence properties. Synthesis under chiral conditions will be used to specifically prepare enantiomerically pure crown-ether coordination compounds with NLO properties and to develop a new class of NLO materials. In addition to luminescent compounds, the concept of cations being too small with respect to the ring-opening diameter of the crown ether shall finally be transferred to compounds with metal-metal bonds and lead to a new cluster chemistry.