The principal of thermally activated delayed fluorescence (TADF) is nowadays one of the most promising concepts for materials used in organic light-emitting diodes (OLEDs). Especially the interest in luminescent copper(I) complexes as TADF materials has risen due to harvesting of both singlet and triplet excitons without the use of heavy and usually rare metals such as iridium or platinum. Furthermore, copper(I) has a large abundance compared to Ir(III) and Pt(II). Complexes with the related atoms gold and silver are also of high interest because of the enhancement of luminescence in the presence of metallophilic interactions, which is particularly true for gold. Besides choosing the right metal, the ligand design is significant to decrease the energy separation between the lowest excited singlet and triplet states for influencing the optoelectronic properties. The preparation of complexes which are simultaneously stable in solution and against redox reactions are additional challenges in finding new and suitable compounds for OLED devices. With the luminescent NHetPhos cooper halide complexes we present a class of soluble complexes with tunable emission properties and wide variety.[2-5]
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Configurations of paracyclophanes
This subgroup’s task is the synthesis of geometrically fixed, chiral polynuclear organometallic complexes and the investigation of their catalytic and optical properties. We use di- and higher functionalized [2.2]paracyclophanes as well as (1,4)benzeno(2,5)pyridinophanes with different donor motifs as ligand systems. The rigid structure of the paracyclophane framework ensures a defined structural relation of the complexed metal centers to each other. The obtained complexes are tested in different reactions as potential asymmetric multi-metal catalysts and, in collaboration with other groups, the cooperation of the metal centers and their optical properties are investigated.
Synthetic routes of different PC derivatives
Starting from [2.2]paracyclophane 4-acetyl-5-hydroxy-[2.2]paracyclophane (AHPC) as well as pyrazole-derivatives were synthesized already. The current research focuses on the synthesis of pyridine-, pyrimidine- and triazole-derivatives.
Synthetic routes for the pyridinophan framework
Similar synthetic routes are available for the pyridinophane framework, while this framework already shows chirality in the unsubstituted form.
Another topic of the group are luminescent metal complexes. These complexes are in focus of many studies for their potential application as OLEDs (organic light emitting diodes) and solar cells. In the OLED field complexes were synthesized that show a significant increase in luminescence, e.g. triplet emitters. Although coordination compounds with triazole ligands and copper are already known, luminescent complexes with ClickPhos ligands are widely unknown. Such compounds have great potential in this field because of their economical synthesis, their good optical properties and the modal structure.
Different ClickPhos-Cu(I)iodine complexes
Through altering the electronic and steric properties of the triazole ligands, the resulting luminescence spectrum is tunable. The introduction of further heteroatoms in the nitrogenous chelating ligands leads to a variety of possible luminescent copper complexes.