A native Coreopsis variant competes more strongly against the invasive Verbena brasiliensis



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Organic light- emitting diodes (OLEDs) are the top-performing technology for flat-panel color displays in smartphones and televisions. Cyclometalated iridium complexes are the most successful class of phosphorescent metal complexes used to produce light in OLEDs. Currently, blue-phosphorescent iridium complexes are the most challenging due to the requirement of the high HOMO-LUMO energy gaps. Strong s-donors are targeted as a supporting ligand for blue-emitting compounds. Acyclic diaminocarbene (ADC) and other strong s-donors ancillary ligands derived from isocyanide precursors are hypothesized to improve the phosphorescence efficiency. Understand the effects of these ancillary ligands on photophysical properties are the key to producing better blue-phosphorescent iridium complexes which are suitable for OLEDs application. Cycolometating ligands are used to control phosphorescence color and fluorinated 2-phenyl pyridine ligands are known to give blue phosphorescence. So fluorinated 2-phenyl pyridine-based cyclometalating ligands are used in this study and paired with different ancillary ligands installed by reactions between azide and isocyanides. Aryl isocyanide ligands with different electronic characteristics (CNAr-dmp, CNAr-NO2, CNAr-OMe, CNtBu) were used to produce different bis-cyclometaled iridium bis-isocyanide complexes. Then the bis-cyclometalated iridium bis-isocyanide complexes react with sodium azide (NaN3) in different solvents (CH2Cl2, CH3CN) at different conditions. This process produces new luminescent structures. These complexes have unique structures but were not obtained by the traditional synthesis route and they have unusual photophysical properties.