Electrogenerated Chemiluminescence from Derivatives of Aluminum Quinolate and Quinacridones:  Cross-Reactions with Triarylamines Lead to Singlet Emission through Triplet−Triplet Annihilation Pathways

Abstract

Solution electrogenerated chemiluminescence (ECL) was evaluated for molecules of interest for organic light-emitting diodes (OLEDs), using high-frequency voltage pulses at a microelectrode. Radical cations of different energies were electrogenerated from a series of triarylamine hole-transport materials (x-TPD), in the presence of radical anions of a high electron affinity sulfonamide derivative of tris(8-hydroxyquinoline)aluminum (Al(qs) 3 ), or a bis(isoamyl) derivative of quinacridone (DIQA). The resultant emission was from the excited singlet states 1 Al(qs) 3 * or 1 DIQA*, the same excited state produced in OLEDs based on these molecules. In solution, the majority of the reaction pairs had insufficient energy to populate 1 Al(qs) 3 * or 1 DIQA* directly, but could form the triplet states 3 Al(qs) 3 * or 3 DIQA*. The reaction order and the temporal response of the emission were consistent with subsequent formation of the excited singlet states via triplet-triplet annihilation (TTA). For reactions with a low excess Gibbs free energy to form the triplet state (∆ T G), the efficiency increased exponentially with an increase in driving force (increase in oxidation potential of x-TPD), then reached a plateau. At the maximum, the efficiencies for formation of 1 Al(qs) 3 * or 1 DIQA* via the TTA route reach as high as a few percent. The computed energetics of these reactions suggest that similar lightproducing electroluminescent reactions, proceeding via triplet formation, could also occur in condensed phase organic thin films.

Ultrasound responsive organogels based on cholesterol-appended quinacridone derivatives with mechanochromic behaviors

“…Weiss and Shinkai have independently reported many interesting studies related to the possible arrangements, mechanisms and functions of such thermoreversible molecular gel systems, containing various rigid chromophores such as porphyrin, perylene, oligo(pphenylenevinylene), azobenzene, and anthracene [27][28][29][30]. The quinacridone (QA) dye with rigid flat framework, excellent optoelectronic [31][32][33][34][35][36] and assembly properties [37][38][39], provides the feasibility of achieving QA-based functional organogels by suitable structural modification. In our previous work, sonication-induced molecular gel has been initially studied based on monocholesterol substituted QA derivatives [40].…”

One pot synthesis of functionalized SBA-15 by using an 8-hydroxyquinoline-5-sulfonamide-modified organosilane as precursor

“…8-Hydroxyquinoline (8-HQ) is one of the most important chelators for metal ions and has been used extensively in a wide variety of analytical techniques and to constructing highly sensitive fluorescent sensors [1][2][3][4][5][6][7][8][9][10][11]. Among the 8-hydroxyquinoline complexes, Tris(8-hydroxyquinoline)aluminum (AlQ 3 ) has been successfully applied in organic light emitting diodes (OLED) [11][12][13][14][15][16][17][18][19] and some of the 8-HQ lanthanide complexes are promising candidates for practical applications in NIR-luminescent optical devices due to their excellent luminescent properties [20][21][22].…”

“…Among the 8-hydroxyquinoline complexes, Tris(8-hydroxyquinoline)aluminum (AlQ 3 ) has been successfully applied in organic light emitting diodes (OLED) [11][12][13][14][15][16][17][18][19] and some of the 8-HQ lanthanide complexes are promising candidates for practical applications in NIR-luminescent optical devices due to their excellent luminescent properties [20][21][22]. In recent years, incorporation of 8-HQ into the nanochannels of mesoporous silica has attracted many efforts for preparation of solid luminescent materials and significant luminescent properties has been obtained by linking the metal complexes to these functionalized mesoporous materials [22][23][24][25][26][27].…”

Dimeric quinacridone cyclophanes: Synthesis, structures, and photophysical properties

“…Nakahara and coworkers have synthesized QA derivatives with alkyl chains and used them in Langmuir-Blodgett films to control the orientation and packing of the chromophores [3,4]. High luminescent efficiencies in dilute solutions combined with good electrochemical stabilities in the solid states enable QA dyes to be promising guest emitting materials in OLEDs [9][10][11][12][13][14][15]. However, the extended -conjugation and rigid planarity make them readily aggregate with neighboring molecules in the condensed phases, hence, dramatically decrease not only their solubility but also the luminescent efficiencies in concentrated solutions or solid states.…”