In-situ luminescence analysis of coordination sensors: looking inside chemical reactions

许多现代技术依赖于发现具有新的或改进的性能的材料，这些材料通常是固体化合物。虽然今天有大量有效的方法，但几乎所有的合成方法都有一个共同的基本原则，即使某些反应物发生反应，只有在反应结束时，才对通常随机形成的产物进行表征。为了开发合理合成固体或发现新化合物的策略，必须在反应过程中详细检查成核，晶体生长或中间体形成等过程。由于这些中间体可以迅速转化为其他相，传统的移地方法不适合。因此，近年来，许多非常有效的方法如x射线衍射、核磁共振和红外光谱被用于化学反应的现场监测。然而，除了许多优点之外，这些方法也有严重的缺点，例如在检测限、时间分辨率或要调查的物质类型方面。一种可以提供额外信息并克服现有表征方法的上述缺点的方法是应用高分辨率CCD探测器的配位传感器的发光分析，该方法迄今尚未用于化学反应的原位监测。在这种方法中，将发射配位传感器作为镧系离子Eu3+， Eu2+， Ce3+引入系统，并在实际反应条件下通过原位发光进行检测和监测（原位发光分析配位传感器- ILACS）。由于这些离子的发光高度依赖于配位环境，因此该方法提供了化学反应过程中配位数、键长、配体共价和阳离子位置对称性变化的信息。该方法容易获得，具有高灵敏度和高时间分辨率的特点，也可用于研究非常小的晶体或非晶材料。因此，这里提出的项目的目的是开发一种新的原位表征方法，并测试其在不同模型系统中的性能。为了组装原位发光测量装置，首先应使用高发光的[Eu（1,10-菲罗啉）2(NO3)3]配合物。然后，更复杂的系统，如磷酸钙和碳酸钙的不同相的转化，以及阐明有关非晶相在结晶开始之前形成的开放性问题，将进行研究。在这种情况下，还需要分析其他碱土金属化合物如SrCO3、BaCO3和SrHPO4是否也会在无定形中间体上形成。

Many modern technologies depend on the discovery of materials with new or improved properties, which are usually solid compounds. Although a very large number of effective methods are available today, almost all synthesis approaches have a basic principle in common, in which certain reactants are brought to react and, only in the end of the reaction, the often randomly formed products are characterized. For developing strategies for a rational synthesis of solids or for discovering new compounds, processes such as nucleation, crystal growth or formation of intermediates must be examined in detail during the reactions. Because these intermediates can rapidly convert to other phases, conventional ex-situ methods are not suitable. Therefore, many very efficient methods such as X-ray diffraction, nuclear magnetic resonance and infrared spectroscopy have been used for in-situ monitoring of chemical reactions in the past few years. However, besides many advantages, these methods have also grave disadvantages as for instance with regard to the detection limit, temporal resolution or type of substances to be investigated. One method that could provide additional information as well as overcome the above mentioned disadvantages of the available characterization methods, is the luminescence analysis of coordination sensors applying high-resolution CCD detectors, which has not yet been used for the in-situ monitoring of chemical reactions so far. Within this approach, emitting coordination sensors as the lanthanide ions Eu3+, Eu2+, Ce3+ are introduced into the system under examination and monitored with the aid of in-situ luminescence under real reaction conditions (in-situ Luminescence Analysis of Coordination sensor - ILACS). Since the luminescence of these ions are highly dependent on the coordination environment, this method provides information about the changes in the coordination number, bond lengths, covalence of the ligands and symmetry of the cation site during chemical reactions. This procedure is easily available, is characterized by high sensitivity and high temporal resolution and can also be used for studying very small crystallites or amorphous materials. Hence, the aim of the here proposed project is to develop a new in-situ characterization method and to test its performance for different model systems. For assembling the in-situ luminescence measurement setup, first the highly luminescent [Eu(1,10-phenanthroline)2(NO3)3] complex shall be applied. Then, more complex systems such as the conversion of different phases of calcium phosphate and carbonate as well as the elucidation of open questions concerning the formation of amorphous phases before the start of their crystallization shall be examined. In this context, it shall be also analyzed whether the formation of other alkaline earth metal compounds such as SrCO3, BaCO3 and SrHPO4 also take place over amorphous intermediates.