136781-07-2Relevant articles and documents
Metal quinolinolate-fullerene(s) donor-acceptor complexes: Evidence for organic LED molecules acting as electron donors in photoinduced electron-transfer reactions
D'Souza, Francis,Maligaspe, Eranda,Zandler, Melvin E.,Subbaiyan, Navaneetha K.,Ohkubo, Kei,Fukuzumi, Shunichi
, p. 16959 - 16967 (2008)
Tris(quinolinolate)aluminum(III) (AlQ3) is the most widely used molecule in organic light-emitting devices. There exists a strong demand for understanding the photochemical and photophysical events originating from this class of molecules. This paper provides the first report on the electron donor ability of MQn (M = Al or Zn for n = 3 or 2) complexes covalently connected to a well-known electron acceptor, fullerene. To accomplish this, fullerene was functionalized with 8-hydroxyquinoline at different ligand positions and their corresponding zinc(II) and aluminum(III) complexes were formed in situ. The weakly fluorescent metal quinolinolate-fullerene complexes formed a new class of donor-acceptor conjugates. The stoichiometry and structure of the newly formed metal quinolinolate-fullerene complexes were established from various spectroscopic methods including matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and computational density functional theory studies. Electrochemical studies involving free-energy calculations suggested the possibility of photoinduced electron transfer from excited metal-quinolinolate complex to the appended fullerene entity. Femtosecond transient absorption studies confirmed such a claim and analysis of the kinetic data allowed us to establish the different photophysical events in sufficient detail. The novel features of this class of donor-acceptor conjugates include faster charge recombination compared to charge separation and decay of the charge-separated state to populate the low-lying fullerene triplet state in competition with direct charge recombination to the ground state.
Understanding M-ligand bonding and: Mer -/ fac -isomerism in tris(8-hydroxyquinolinate) metallic complexes
Lima, Carlos F.R.A.C.,Taveira, Ricardo J. S.,Costa, José C. S.,Fernandes, Ana M.,Melo, André,Silva, Artur M. S.,Santos, Luís M.N.B.F.
, p. 16555 - 16565 (2016/07/06)
Tris(8-hydroxyquinolinate) metallic complexes, Mq3, are one of the most important classes of organic semiconductor materials. Herein, the nature of the chemical bond in Mq3 complexes and its implications on their molecular properties were investigated by a combined experimental and computational approach. Various Mq3 complexes, resulting from the alteration of the metal and substitution of the 8-hydroxyquinoline ligand in different positions, were prepared. The mer-/fac-isomerism in Mq3 was explored by FTIR and NMR spectroscopy, evidencing that, irrespective of the substituent, mer- and fac-are the most stable molecular configurations of Al(iii) and In(iii) complexes, respectively. The relative M-ligand bond dissociation energies were evaluated experimentally by electrospray ionization tandem mass spectrometry (ESI-MS-MS), showing a non-monotonous variation along the group (Al > In > Ga). The results reveal a strong covalent character in M-ligand bonding, which allows for through-ligand electron delocalization, and explain the preferred molecular structures of Mq3 complexes as resulting from the interplay between bonding and steric factors. The mer-isomer reduces intraligand repulsions, being preferred for smaller metals, while the fac-isomer is favoured for larger metals where stronger covalent M-ligand bonds can be formed due to more extensive through-ligand conjugation mediated by metal d orbitals.
A theoretical and experimental study on meridional-facial isomerization of tris(quinolin-8-olate)aluminum (Alq3)
Iwakura,Ebina,Komori-Orisaku,Koide
, p. 12824 - 12827 (2014/08/18)
The rationale behind the stereospecific synthesis of a facial isomer of tris(quinolin-8-olate)aluminum (Alq3) is studied by density functional theory (DFT) calculations, which predict the favourable influence of an H3O+ ion on the distribution ratio between a meridional and a thermodynamically unstable facial isomer. This journal is the Partner Organisations 2014.
