Introducing Bluish-Green Light-Emitting Diodes (OLEDs) and Tuning Their Color Intensity by Uranium Complexes: Synthesis, Characterization, and Photoluminescence Studies of 8-Hydroxyquinoline Complexes of Uranium

Abstract

To improve our understanding of the chemistry of actinide complexes and to spur their development in the field of actinide markers, two new uranium complexes were synthesized using 8-hydroxyquinoline and 5,7-dichloro-8-hydroxyquinoline. The prepared complexes were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, ultraviolet− visible spectroscopy, elemental analysis, and single-crystal X-ray diffraction. The impact of the electron-withdrawing group of the ligand on the photoluminescence spectra of the complexes in solution and in the solid state was scrutinized. The bandgap of the complexes was calculated using the density functional theory (DFT) method to investigate the effects of the electron-withdrawing groups on energy levels. The synthesized uranium complexes demonstrated appropriate levels of the lowest unoccupied molecular orbital energy, leading to favorable dye stability. The prepared uranium complexes showed blue fluorescent emission, and the sample with the most intense fluorescence was used to construct bluish-green organic light-emitting diodes using simple solution processing fabrication methods. Absorbance spectra, emission spectra, DFTcalculated energy levels, and comparisons of the fabricated organic light-emitting diodes indicated that the electron-withdrawing group was a key factor in photoluminescence behavior.

Lightning Up the Structural Complexity: Challenging Bromine’s ‘Heavy’ Reputation in Fluorescence Properties of Organic–Inorganic Hybrid Materials with 5,7-Dichloro-8-Hydroxyquinolinium

“…These compounds consist of a protonated 5,7-dichloro-8-hydroxyquinoline (hereinafter referred to as 8hqCl 2 , Figure ), a halogenometalate anion, and incorporate either open-shell [Fe­(III), Cu­(II)] or closed-shell [Zn­(II), Cd­(II), Hg­(II), Sn­(IV)] systems. As an organic component, 8hqCl 2 demonstrates great promise due to its strong fluorescence , making it a compelling candidate for diverse applications, including utilization in light-emitting diodes (LEDs) and sensors. , What is more, 8-hydroxyquinoline derivatives, along with other similar compounds, exhibit the ability to bind to and transport metal ions across cell membranes due to their metal-binding and ionophore properties. ,− By capitalizing on these features, it might be feasible to engineer hybrid materials that offer controlled charge transport, which is an essential factor in enhancing the efficiency of photovoltaic cells.…”