Dinuclear Zn II Complexes Exhibiting Thermally Activated Delayed Fluorescence and Luminescence Polymorphism
| Autor: | Kai Li, Chuluo Yang, Chao Wu, Yaxiong Wei, Jinfan Xiong, Teng Teng, Xiaoyong Chang |
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| Rok vydání: | 2020 |
| Předmět: |
Mechanochromic luminescence
Photoluminescence 010405 organic chemistry Chemistry Organic Chemistry General Chemistry 010402 general chemistry Photochemistry 01 natural sciences Fluorescence Catalysis 0104 chemical sciences Metal Excited state visual_art visual_art.visual_art_medium Luminescence Ground state HOMO/LUMO |
| Zdroj: | Chemistry – A European Journal. 26:6887-6893 |
| ISSN: | 1521-3765 0947-6539 |
| DOI: | 10.1002/chem.202000572 |
| Popis: | ZnII complexes exhibiting strong emission in the solid state remain scarce, and most of them exhibit only prompt fluorescence. Herein the synthesis, structures, and photoluminescence properties of two ZnII complexes containing new donor-acceptor ligands is reported. The new ZnII complexes have dinuclear structures in which each metal ion adopts a distorted square-pyramidal geometry. The ZnII complexes show strong emission in the solid state with quantum yields up to 50 %. Variable-temperature transient photoluminescence studies revealed an emission mechanism involving prompt and thermally activated delayed fluorescence (TADF). DFT calculations showed well-separated HOMO and LUMO in the ground state and small excited singlet-triplet energy splitting, accounting for the TADF. The complexes also exhibit different emission colors in the as-synthesized powder state and in single crystals, that is, they exhibit luminescence polymorphism. The single-crystal emission is responsive to mechanical grinding and was characterized by powder XRD. |
| Databáze: | OpenAIRE |
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