Modellsysteme für die Gallium-Extraktion, I. Struktur und Moleküldynamik von Aluminium- und Galliumtris(oxinaten) / Model Systems for Gallium Extraction, I. Structure and Molecular Dynamics of Aluminium and Gallium Tris(oxinates)

Abstract

Tris(oxinato) complexes of aluminium(III) and gallium(III) have been prepared from 8-oxyquinoline (OxH) and its six C-methylated derivatives from aqueous solutions of the metal chlorides or nitrates and an ammonium acetate buffer. Crystalline monohydrates or (upon precipitation with methanol) mono-methanol adducts are obtained. Single crystal X-ray diffraction studies reveal a meridional tris(chelate) structure for the two (isomorphous) tris(oxinates) Al(Ox)3 · MeOH and Ga(Ox)3 · MeOH with distinct differences in the individual dimensions. (The MeOH molecules form strong hydrogen bonds with one of the oxygen atoms.) For these species and those of the substituted ligands 3-MeOx, 4-MeOx, 5-MeOx, 6-MeOx, and 7-MeOx a similar meridional structure was confirmed by low temperature 1H NMR spectroscopy, which showed three inequivalent sets of ligands in each case. The collaps of these signals at elevated temperatures indicates a ligand-equilibrating process, with the mechanism probably comprising a dissociation of a pyridine function from the metal, to give a fluctional pentacoordinate species with free rotation about the intact M—O bond, and an M—N recombination at a random octahedral site. For the 2-MeOx ligands, however, the facial structure is preferred at lower temperature, but with the meridional isomer present as a component of an equilibrium. This indicates the strong steric influence of substituents in 2-position of the 8-oxy-quinoline.

Chemical failure modes of AlQ3-based OLEDs: AlQ3 hydrolysis

“…The ground-state structure of AlQ3 has been studied extensively by a number of groups and the results of the present calculations are in excellent agreement with previous theoretical determinations [35][36][37][38][39][40] and experimental measurements. 41,42 The bond distances of the inner coordination sphere are given in Table 1, and are within 0.02 Å of previous high level calculations 9 and within o0.035 Å of X-ray determinations. The orbital energies for mer-AlQ3 computed at the B3-PW91/6-31G(d) level of theory are À5.43, À5.33 and À5.10 eV and À1.83, À1.59 and À1.51 eV for the HOMO and LUMO triplets, respectively.…”

Electronic structure and molecular orbital study of the first excited state of the high‐efficiency blue OLED material bis(2‐methyl‐8‐quinolinolato)aluminum(III) hydroxide complex from ab initio and TD‐B3LYP

“…All those mentioned above indicate that the aluminumOnitrogen becomes weaker. The bond distances of AlON are 2.08, 2.06, and 2.13 Å (computed value, B3LYP/6-31G*) [17] and 2.04, 2.03, and 2.08 Å(experimental values) [18,19] in alq3, compared with the AlON bond distances computed with the B3LYP/6-31G* method in AlMq 2 OH, which are shorter. The difference of optical luminescence and electrical luminescence between Alq3 and Gaq3 does not originate from the participation of the d orbital of Ga, while the structure change for the difference of metallic radius may be the key [20].…”

Syntheses and structures of new luminescent B(III) complexes: BPh2(2-(2-pyridyl)naphtho[b]imidazole) and BF2(2-(2-pyridyl)naphtho[b]imidazole)

“…Since an organic light emitting diode (OLED) was reported by Tang and Vanslyke [4], LEDs based on organic materials have generated considerable interest and enabled the development of low-cost, fullcolor, flat-panel displays [5][6][7][8]. The best-known EL metal complex used in OLED is Alq 3 which is not only a good emitter but also a highly efficient electron-transporting material, where q is the 8-hydroxyquinolinato ligand [9,10]. Via the modification of the ligand of metal complex, the emission spectra of devices and other properties, such as thermostability and carrier mobility, can be tuned.…”