Photoluminescence enhancement of Re(i) carbonyl complexes bearing D–A and D–π–A ligands. Issue 14 (17th March 2020)

• Record Type: Journal Article
• Authors: Maroń, Anna M.; Szlapa-Kula, Agata; Matussek, Marek; Kruszynski, Rafal; Siwy, Mariola; Janeczek, Henryk; Grzelak, Justyna; Maćkowski, Sebastian; Schab-Balcerzak, Ewa; Machura, Barbara
• Is Part Of: Dalton transactions. Volume 49:Issue 14(2020)
• Page Start: 4441
• Page End: 4453
• Publication Date: 2020-03-17
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c9dt04871e
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : The impact of highly electron donating units appended to the imine ligand on the thermal and optoelectronic properties of Re(i ) complexes was investigated. Abstract : Three Re(i ) carbonyl complexes [ReCl(CO)3 (L n )] bearing 2, 2′-bipyridine, 2, 2′:6′, 2′′-terpyridine, and 1, 10-phenanthroline functionalized with diphenylamine/or triphenylamine units (L 1 –L 3 ) were synthesized to explore the impact of highly electron donating units appended to the imine ligand on the thermal and optoelectronic properties of Re(i ) systems. Additionally, for comparison, the ligands L 1–3 and parent complexes [ReCl(CO)3 (bipy)], [ReCl(CO)3 (phen)] and [ReCl(CO)3 (terpy-κ 2 N)] were investigated. The thermal stability was evaluated by differential scanning calorimetry. The ground- and excited-state electronic properties of the Re(i ) complexes were studied by cyclic voltammetry and differential pulse voltammetry, absorption and emission spectroscopy, as well as using density-functional theory (DFT). The majority of the compounds form amorphous molecular materials with high glass transition temperatures above 100 °C. Compared to the unsubstituted complexes [ReCl(CO)3 (bipy)], [ReCl(CO)3 (phen)] and [ReCl(CO)3 (terpy-κ 2 N)], the HOMO–LUMO gap of the corresponding Re(i ) systems bearing modified imine ligands is reduced, and the decrease in the value of the Δ E H–L is mainly caused by the increase in HOMO energy level. In relation to the parent complexes, all designed Re(i ) carbonyls were found to show enhanced photoluminescence, both in solution and in solid state. The investigated ligands and complexes were also preliminarily tested as luminophores in light emitting diodes with the structures ITO/PEDOT:PSS/compound/Al and ITO/PEDOT:PSS/PVK:PBD:compound/Al. The pronounced effect of the ligand chemical structure on electroluminescence ability was clearly visible.