Aluminum 8-hydroxyquinoline

An example "double heterostructure" OLED shown in Figure 7c uses an ITO coated glass substrate, upon which a hole transporting layer, typically composed of a tertiary amine (eg, IV,IV-biphenyl-A IV7-bis(3-methylphenyl)l-l biphenyl-4,4 diamine, abbreviated TPD), a thin film of an emissive material such as aluminum-8-hydroxyquinoline(Alq3) and an electron-transporting layer (often an oxidiazole derivative) are sequentially deposited in vacuum (Fig. 

A. Misra, P. Kumar, M.N. Kamalasanan, S.C. Jain, Synthesis and characterization of some 5-coordinated aluminum-8-hydroxyquinoline derivatives for OLED applications, to be published. 

Week [4] prepared photoluminescent polynorborene derivatives, (VII), by polymerizing aluminum-8-hydroxyquinoline-functionalized norborene, (VI), using benzylidene (l,3-dimesitylimidazolydin-2-ylidene)-(tricyclohexylpho-sphine)ruthenium dichloride. 

Fenbuconazole Fenfuram Fenpropimorph Flutriafol Fosetyl-aluminum 8-Hydroxyquinoline sulfate Imazalil Oxycarboxin Tebuconazole Thiophanate Triadimenol Tridemorph fungicide, systemic agric. 

Despite the ubiquity of aluminum hydroxyquinolinate chelates as ETMs, other metal chelates of substituted 8-hydroxyquinoline, such as Group II metal ions of Zn2+ and Be2+ have also been used as the ETM in OLEDs (Scheme 3.28) [131-133],... 

The phenomenon of organic EL was first demonstrated using a small-molecule fluorescent emitter in a vapor-deposited OLED device. The Kodak group first used metal oxinoid materials such as the octahedral complex aluminum tris-8-hydroxyquinoline (Alq3) (discussed above as an ETM) as the fluorescent green emitter in their pioneering work on OLED architectures [167],... 

J. Lee, Y. Park, S.K. Lee, E.J. Cho, D.Y. Kim, H.Y. Chu, H. Lee, L.M. Do, and T. Zyung, Tris-(8-hydroxyquinoline)aluminum-based organic light-emitting devices with Al/CaF2 cathode performance enhancement and interface electronic structures, Appl. Phys. Lett., 80 3123-3125 (2002). 

K.A. Higginson, X. Zhang, and F. Papadimitrakopoulos, Thermal and morphological effects on the hydrolytic stability of Aluminum Tris(8-hydroxyquinoline) (Alq3), Chem. Mater., 10 1017— 1020 (1998). 

J. Yu, Z. Chen, Y. Sakuratani, H. Suzuki, M. Tokita, and S. Miyata, A novel blue light emitting diode using tris(2,3-dimethyl-8-hydroxyquinoline) Aluminum(III) as emitter, Jpn. J. Appl. Phys., 38 6762-6763 (1999). 

The criteria for good electron transport materials are that they should transport electrons, block holes, and have a small barrier to electron injection from the metal cathode. The most commonly used ETL in vacuum-deposited OLEDs is tris-(8-hydroxyquinoline) aluminum (Alq3), as shown in Figure 7.7. Alq3 for example, has a LUMO energy level of 3 eV [65] and an electron mobility of 5x 10 5 cm2/(V s) [66]. 

VE Choong, Y Park, N Shivaparan, CW Tang, and Y Gao, Deposition-induced photoluminescence quenching of tris-(8-hydroxyquinoline) aluminum, Appl. Phys. Lett., 71 1005-1007, 1997. 

H Aziz, Z Popovic, S Xie, A-M Hor, N-X Hu, C Tripp, and G Xu, Humidity-induced crystallization of tris(8-hydroxyquinoline) aluminum layers in organic light-emitting devices, Appl. Phys. Lett., 72 756-758, 1998. 

The ligand is hydroxyquinoline-sulfonate (HQS) which forms fluorescent AI-HQS complexes in solution. HQS forms surface complexes with the Al-centers of aluminum oxide surface these surface complexes are also fluorescent. Fluorescence as a function of time during HQS-promoted dissolution of aluminum oxide. Surface-associated fluorescence was calculated from the difference between measured total and dissolved fluorescence. 

There are many interesting derivatives of quinoline and acridine obtained by substitution. In particular, 8-hydroxyquinoline (oxine) is the second complexing agent in importance after EDTA. Sulfonation in position 5 leads to a compound which is soluble in water and that exhibits outstanding fluorogenic properties (i.e. fluorescence enhancement) on complexation with metal ions (e.g. aluminum). 

Mahapatro AK, Agrawal R, Ghosh S (2004) Electric-field-induced conductance transistion in 8-hydroxyquinoline aluminum (Alq3). J Appl Phys 96 3583... 

Synopsis of Halls and Schlegel (2001) Molecular Orbital Study of the First Excited State of the OLED Material f 75 (8-hydroxyquinoline)aluminum(ni) . 

The Br2 can be used to analyze many unsaturated oiganic compounds. Al3+ was analyzed as follows An unknown was treated with 8-hydroxyquinoline (oxine) at pH 5 to precipitate aluminum oxinate, AI(C9H6ON)3. The precipitate was washed, dissolved in warm HC1 containing excess KBr, and treated with 25.00 mL of 0.020 00 M KBr03. 

Why is it difficult to extract the EDTA complex of aluminum into an oiganic solvent but easy to extract the 8-hydroxyquinoline complex ... 

Owing to steric hindrance (Section 10.2.2.3) the tris complex of aluminum with 2-methyl-8-hydroxyquinoline cannot form in aqueous solution so that this reagent can be used to solvent extract other metals from aluminum, which can then be solvent extracted in its turn and determined with unsubstituted 8-hydroxyquinoline.24 25 52... 

Other diprotonated acyl-pyridines have likewise been studied.61 In studies of 5-, 6-, 7-, and 8-hydroxyquinolines and 5-hydroxyisoquinoline, dicationic intermediates like 185 (Table 4) were found to be involved in superacid catalyzed reactions with benzene and cyclohexane.59 For example, 8-hydroxyquinoline (187) reacts in CF SOsH-SbFs to generate dications (188 and 189) and undergoes ionic hydrogenation in the presence of cyclohexane (eq 64). Compound 187 also reacts with benzene in suspensions of aluminum halides (eq 65). 

Interestingly, the comparable monocation (190) is not reactive towards benzene or cyclohexane. This is an indication of the superelectrophilic character of dication 188. The isomeric hydroxyquinolines and 5-hydroxy-isoquinoline react with 5-7 molar excess of aluminum chloride and cyclohexane at 90°C to give ionic hydrogenation products, and the corresponding distonic superelectrophiles (191-193) are proposed as intermediates. 

Low concentrations of aluminum and beryllium can be determined by chelating with 8-hydroxyquinoline and extracting the chelates into MIBK and aspirating into a N20-acetylene flame. 

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