Comparative studies on OLED performances of chloro and fluoro substituted Zn(ii) 8-hydroxyquinolinates

Abstract

Two novel 8-hydroxyquinoline metallic derivatives, (E)-2- [(2,3,4,5-tetrafluorophenyl)ethenyl]-8-hydroxyquinolate zinc (5) and (E)-2-[2-(2,6-dichlorophenyl)ethenyl]-8-hydroxyquinolate zinc (6) were synthesized and characterized by 1 H NMR, ESI-MS, FT-IR and elemental analysis. Photoluminescence spectra revealed that the complexes showed strong fluorescence with maximum emissions at 575 and 607 nm. Compared with that of complex 5, the fluorescence quantum yield and average fluorescence lifetime of complex 6were efficiently reduced. The heavy atom effect of Cl and distinct molecular interactions were found to play an important role in modulating or improving the properties of the complexes. Multilayer organic light-emitting diodes (OLEDs) were fabricated using these complexes. The results show they are good candidates for yellow OLEDs with maximum luminance of 7123 cd m À2 for compound 5 and 9143 cd m À2 for compound 6, as well as luminance efficiencies of 2.26 cd A À1 and 2.60 cd A À1 , respectively. As the substituents are changed from fluorine to chlorine, the organic electroluminescent device based on the complex 6 shows overall better performance than that of complex 5. The calculated HOMO-LUMO energy gaps for complexes 5 and 6 were in good agreement with the experimental results.

Two 8-Hydroxyquinolinate Based Supramolecular Coordination Compounds: Synthesis, Structures and Spectral Properties

“…The thermal stabilities of the two crystalline solids were determined by thermal analysis technique. Thermogravimetric analyses (TGA) of 1 and 2 shown no appreciable weight loss until the temperature reaches around 370 °C for 1 and 395 °C for 2 , respectively, this thermal behavior is similar to that of other metal quinolates [ 9 , 33 ] (see Figure 6 ). The TGA results suggest that the two supramolecular architectures are thermally robust, which are attributed to highly polarized Cr-N and Cr-O bonds.…”

“…Unlike 1 , the construction of a 3D supramolecular network employing these 2D layers is assisted not only by the weak intermolecular C-H···π interactions [C(50)-H(50)···π = 3.710(7) Å] but also by the C-Cl···π interactions [C(100)-Cl···π = 3.654(3) Å] and C-H···Cl interactions (C(55)-H(55)···Cl(3) = 3.286(5) Å). This is primarily due to the replacement of -NO 2 group by the chlorine atom on the bidentate chelate ligand, leading to different intermolecular interactions in the solid state [ 8 , 9 ]. In addition, compound 2 is almost non-porous supramolecular coordination polymers with only 2.1% of void space as calculated by PLATON (see Figure 4 b) [ 31 ].…”

“…In recent years, particular interest has been given to the supramolecular coordination compounds based on 8-hydroxyquinoline derivatives [7,8,9,10,11]. Because of the ease of preparation and chemical modification of 8-HQ, various 8-hydroxyquinoline derivatives with different substituents are employed to construct metal complexes with desired structure and properties relying on the non-covalent intra- and intermolecular forces [12,13,14].…”

“…Complexes of various metals with 8-hydroxyquinoline (HQ) or its derivatives have attracted considerable attention owning to their biological activities and promising application in organic light-emitting diodes (OLEDs), optical sensing, and so on [ 1 , 2 , 3 , 4 , 5 , 6 ]. In recent years, particular interest has been given to the supramolecular coordination compounds based on 8-hydroxyquinoline derivatives [ 7 , 8 , 9 , 10 , 11 ]. Because of the ease of preparation and chemical modification of 8-HQ, various 8-hydroxyquinoline derivatives with different substituents are employed to construct metal complexes with desired structure and properties relying on the non-covalent intra- and intermolecular forces [ 12 , 13 , 14 ].…”

Novel liquid crystalline organic semiconducting oligomers incorporating N-heterocyclic carbazole moieties for fluorescent OLEDs

“…calculations were performed to evaluate the frontier molecular orbitals and optimized geometrically molecular configuration of the compounds at the B3PW91/ 6-31 G (d) level. DFT calculations were computationally processed in theoretical gaseous conditions so that the interaction of these molecules and the solvent can be eliminated [58][59].…”