Multicolor Emissive Phosphorescent Iridium(III) Complexes Containing L-Alanine Ligands: Photophysical and Electrochemical Properties, DFT Calculations, and Selective Recognition of Cu(II) Ions

• Published in: Molecules (Basel, Switzerland) Switzerland), 2022-12, Vol.27 (23), p.8506
• Main Authors: Chu, Xi, Huang, Yichuan, Li, Wenhao, Zhao, Shisheng, Li, Hongyan, Lu, Aidang
• Format: Article
• Language: English
• Subjects: Acetonitrile; Alanine; Chemical sensors; Chemoreceptors; Copper; Density functional theory; Electrochemical analysis; Electrochemistry; Emissions; Energy; Fluorine; fluorine-substituted cyclometalated ligands; Ions; Ir(III) complexes; Iridium - chemistry; Iridium compounds; L-Alanine; Ligands; Luminescence; Molecular orbitals; Nitrogen; Organometallic Compounds - chemistry; Phosphorescence; Photoluminescence; Photons; Pyridines; Response time; Selectivity; sensing copper ions; Spectrum analysis
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules27238506

Three novel Ir(III) complexes, (ppy) Ir(L-alanine) ( ) (ppy = 2-phenylpyridine), (F ppy) Ir(L-alanine) ( ) (F ppy = 2-(4-fluorophenyl)pyridine), and (F ppy) Ir(L-alanine) ( ) (F ppy = 2-(2,4,5-trifluorophenyl)pyridine), based on simple L-alanine as ancillary ligands were synthesized and investigated. Due to the introduction of fluorine substituents on the cyclometalated ligands, complexes - exhibited yellow to sky-blue emissions ( = 464-509 nm) in acetonitrile solution. The photoluminescence quantum yields (PLQYs) of - ranged from 0.48-0.69, of which with sky-blue luminescence had the highest PLQY of 0.69. The electrochemical study and density functional theory (DFT) calculations show that the highest occupied molecular orbital (HOMOs) energy of - are stabilized by the introduction of fluorine substituents on the cyclometalated ligands, while L-alanine ancillary ligand has little contribution to HOMOs and lowest unoccupied molecular orbitals (LUMOs). Moreover, - presented an excellent response to Cu with a high selectivity, strong anti-interference ability, and short response time. Such a detection was based on significant phosphorescence quenching of their emissions, showing the potential application in chemosensors for Cu .