Assist.-Prof. Dr. Heidi Annemarie Reichl
Photoactive Hybrid Systems
The research focus of the group is on the development of photoactive inorganic-organic hybrid materials. Hybrid materials are substances that consist of at least two components and exhibit new properties in combination. For example, the combination of porous host structures with photoactive molecules and complexes makes it possible to achieve photoswitchability (e.g. change in colour when exposed to light) and luminescent properties similar to those in solution or even more efficient. These properties can be specifically adjusted by selecting the appropriate host matrix and guest. This is particularly interesting with regard to applications in data storage, sensors or OLEDs.
The group studies photoactive hybrid materials consisting of metal-organic frameworks (MOFs) and photochromic/luminescent (in-)organic molecules and complexes. Photoactive substances primarily show their optical properties in solution, which are limited in solids by steric hindrance. Insertion into a MOF host has the advantage that the species in question are separated from each other. On the one hand, this means that light-induced isomerisation processes are enabled in solids, and on the other hand, phenomena such as the quenching of luminescence through aggregation can be prevented. In addition, the physicochemical properties of MOFs can be varied by selectively changing the individual building blocks and thus the desired properties can be set, which in turn modulates the optical response of the overall material.
The two- or multi-component systems are synthesized in various ways, ranging from “one-pot” syntheses to diffusion loading, gas-phase loading and mechanochemistry. The optical properties of the resulting materials are analyzed using various diffractometric and spectroscopic methods.
In order to understand the resulting optical properties of a hybrid material and, above all, to adjust them in a targeted manner, the nature of the interaction between the individual components must be understood. By combining various analytical methods (ssNMR, total X-ray scattering coupled to PDF, IR and UV/Vis spectroscopy) with modelling, photoactive hybrid systems are to be fully characterised and the structure-property relationships structurally derived. The characterisation work flow established in this way can then be transferred to other (partially) amorphous systems.