Efficient photovoltaic and electroluminescent perovskite devices

Planar diode structures employing hybrid organic-inorganic methylammonium lead iodide perovskites lead to multifunctional devices exhibiting both a high photovoltaic efficiency and good electroluminescence. The electroluminescence strongly improves at higher current density applied using a pulsed driving method

[Ir(C^N)2(N^N)]+ emitters containing a naphthalene unit within a linker between the two cyclometallating ligands

The synthesis of four cyclometallated [Ir(C^N) 2 (N^N)][PF 6 ] compounds in which N^N is a substituted 2,2’- -bipyridine (bpy) ligand and the naphthyl-centred ligand 2,7-bis(2-(2-(4-(pyridin-2-yl)phenoxy)ethoxy) ethoxy)naphthalene provides the two cyclometallating C^N units is reported. The iridium( III ) complexes have been characterized by 1 H and 13 C NMR spectroscopies, mass spectrometry and elemental analysis, and their electrochemical and photophysical properties are described. Comparisons are made with a model [Ir(ppy) 2 (N^N)][PF 6 ] compound (Hppy = 2-phenylpyridine). The complexes containing the naphthyl-unit exhibit similar absorption spectra and excitation at 280 nm leads to an orange emission. The incorporation of the naphthalene unit does not lead to a desirable blue contribution to the emission. Density functional theory calculations were performed to investigate the geometries of the complexes in their ground and first triplet excited states, as well as the energies and compositions of the highestoccupied and lowest unoccupied molecular orbital (HOMO and LUMO) manifolds. Trends in the HOMO– LUMO gaps agree with those observed electrochemically. The energy difference between the LUMO and the lowest unoccupied MO located on the naphthyl unit (LUMO+7) is large enough to explain why there is no contribution from the naphthyl-centred triplet excited state to the phosphorescence emission. Singlet excited states were also investigated. Light-emitting electrochemical cells (LECs) using the [Ir(C^N) 2 (N^N)][PF 6 ] and [Ir(ppy) 2 (N^N)][PF 6 ] complexes in the emissive layer were made and evaluated. The presence of the naphthyl-bridge between the cyclometallating units does not significantly alter the device response

Shine bright or live long: substituent effects in [Cu(N^N)(P^P)]+-based light-emitting electrochemical cells where N^N is a 6-substituted 2,2'-bipyridine

We report [Cu(P^P)(N^N)][PF6] complexes with P^P = bis(2-(diphenylphosphino)phenyl)ether (POP) or 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (xantphos) and N^N = 6-methyl-2,2′-bipyridine (Mebpy), 6-ethyl-2,2′-bipyridine (Etbpy), 6,6′-dimethyl-2,2′-bipyridine (Me2bpy) or 6-phenyl-2,2′-bipyridine (Phbpy). The crystal structures of [Cu(POP)(Phbpy)][PF6]·Et2O, [Cu(POP)(Etbpy)][PF6]·Et2O, [Cu(xantphos)(Me2bpy)][PF6], [Cu(xantphos)(Mebpy)][PF6]·CH2Cl2·0.4Et2O, [Cu(xantphos)(Etbpy)][PF6]·CH2Cl2·1.5H2O and [Cu(xantphos)(Phbpy)][PF6] are described; each copper(I) centre is distorted tetrahedral. In the crystallographically determined structures, the N^N domain in [Cu(xantphos)(Phbpy)]+ and [Cu(POP)(Phbpy)]+ is rotated ∼180° with respect to its orientation in [Cu(xantphos)(Mebpy)]+, [Cu(POP)(Etbpy)]+ and [Cu(xantphos)(Etbpy)]+; in each complex containing xantphos, the xanthene ‘bowl’ retains the same conformation in the solid-state structures. The two conformers resulting from the 180° rotation of the N^N ligand were optimized at the B3LYP-D3/(6-31G**+LANL2DZ) level and are close in energy for each complex. Variable temperature NMR spectroscopy evidences the presence of two conformers of [Cu(xantphos)(Phbpy)]+ in solution which are related by inversion of the xanthene unit. The complexes exhibit MLCT absorption bands in the range 378 to 388 nm, and excitation into each MLCT band leads to yellow emissions. Photoluminescence quantum yields (PLQYs) increase from solution to thin-film and powder; the highest PLQYs are observed for powdered [Cu(xantphos)(Mebpy)][PF6] (34%), [Cu(xantphos)(Etbpy)][PF6] (37%) and [Cu(xantphos)(Me2bpy)][PF6] (37%) with lifetimes of 9.6–11 μs. Density functional theory calculations predict that the emitting triplet (T1) involves an electron transfer from the Cu–P^P environment to the N^N ligand and therefore shows a 3MLCT character. T1 is calculated to be ∼0.20 eV lower in energy than the first singlet excited state (S1). The [Cu(P^P)(N^N)][PF6] ionic transition-metal (iTMC) complexes were tested in light-emitting electrochemical cells (LECs). Turn-on times are fast, and the LEC with [Cu(xantphos)(Me2bpy)][PF6] achieves a maximum efficacy of 3.0 cd A−1 (luminance = 145 cd m−2) with a lifetime of 1 h; on going to the [Cu(xantphos)(Mebpy)][PF6]-based LEC, the lifetime exceeds 15 h but at the expense of the efficacy (1.9 cd A−1). The lifetimes of LECs containing [Cu(xantphos)(Etbpy)][PF6] and [Cu(POP)(Etbpy)][PF6] exceed 40 and 80 h respectively

Highly Stable Red-Light-Emitting Electrochemical Cells

The synthesis and characterization of a series of new cyclometalated iridium(III) complexes [Ir(ppy) 2 (N ∧ N)][PF 6 ] in which Hppy = 2-phenylpyridine and N ∧ N is (pyridin-2-yl)benzo[ d ]thiazole ( L1 ), 2-(4-( tert -butyl)pyridin-2-yl)benzo[ d ]thiazole ( L2 ), 2-(6-phenylpyridin-2-yl)benzo[ d ]thiazole ( L3 ), 2-(4-( tert -butyl)-6-phenylpyridin-2-yl)benzo[ d ]thiazole ( L4 ), 2,6-bis(benzo[ d ]thiazol-2-yl)pyridine ( L5 ), 2-(pyridin-2-yl)benzo[ d ]oxazole ( L6 ), or 2,2′-dibenzo[ d ]thiazole ( L7 ) are reported. The single crystal structures of [Ir(ppy) 2 ( L1 )][PF 6 ]·1.5CH 2 Cl 2 , [Ir(ppy) 2 ( L6 )][PF 6 ]·CH 2 Cl 2 , and [Ir(ppy) 2 ( L7 )][PF 6 ] have been determined. The new complexes are efficient red emitters and have been used in the active layers in light-emitting electrochemical cells (LECs). The effects of modifications of the 2-(pyridin-2-yl)benzo[ d ]thiazole ligand on the photoluminescence and LEC performance have been examined. Extremely stable red-emitting LECs are obtained, and when [Ir(ppy) 2 ( L1 )][PF 6 ], [Ir(ppy) 2 ( L2 )][PF 6 ], or [Ir(ppy) 2 ( L3 )][PF 6 ] are used in the active layer, device lifetimes greater than 1000, 6000, and 4000 h, respectively, are observe

Aplicación de la topología molecular al análisis de la actividad antimalárica de 4-Aminobiciclo[2.2.2]Octan-2-il 4-Aminobutanoatos y sus análogos etanoatos y propanoatos

La malaria es una enfermedad que causa uno de los mayores índices de mortalidad en todo el mundo. Actualmente, el número de casos y muertes continúa en aumento, debido a, entre otros factores, la resistencia que el parásito ha desarrollado frente a los tratamientos. Con el tiempo, se han estudiado nuevas moléculas para ser utilizadas como tratamiento frente a esta enfermedad. En este estudio se realizó un análisis de la actividad antimalárica de los 4-Aminobiciclo[2.2.2] octan-2-il 4-aminobutanoatos y sus análogos etanoatos y propanoatos, usando la topología molecular para desarrollar un modelo de relación cuantitativa estructura-actividad QSAR. Mediante el empleo del análisis lineal discriminante se seleccionó una función capaz de clasificar correctamente 32 de 35 compuestos analizados según su actividad antimalárica. El modelo clasificó el 82,35 % de las moléculas consideradas activas de manera experimental y discriminó el 100 % de las moléculas inactivas como tales. Aplicando el análisis de regresión multilineal se seleccionó una función capaz de predecir la actividad antimalárica de cada compuesto en términos de pIC 50. Para la validación del modelo se emplearon la técnica de validación cruzada y un test de aleatoriedad. Tras este análisis, se han propuesto nuevas estructuras antimaláricas potencialmente activas.Malaria causes one of the highest mortality rates worldwide. Malaria cases and malaria deaths are still increasing due to, among other factors, the resistance that the parasite has developed to treatments. New molecules have been analyzed to be used as treatment for this disease. The present study predicts the antiplasmodial activity of the Aminobicyclo[2.2.2]octan-2-yl 4-aminobutanoates and their equivalents ethanoates and propanoates using molecular topology to develop a quantitative structure-activity relation (QSAR) model. Linear discriminant analysis was used to find a mathematical statement able to classify 32 of 35 compounds accurately by their antiplasmodial activity. The model classified 82.35 % of molecules considered active with experimental methods, and differentiated 100 % of the inactive molecules as such. Multilinear regression analysis was applied to find an equation with the ability to predict the antiplasmodial activity of each compound in terms of pIC50. Crossvalidation and randomness tests were carried out to validate this model. Finally, new potential antiplasmodial molecules have been proposed.Ciencias Experimentale

Luminescent osmium(II) bi-1,2,3-triazol-4-yl complexes: photophysical characterisation and application in light-emitting electrochemical cells

The series of osmium(II) complexes [Os(bpy)3-n(btz)n][PF6]2 (bpy = 2,2’-bipyridyl, btz = 1,1’-dibenzyl-4,4’-bi-1,2,3-triazolyl, 1 n = 0, 2 n = 1, 3 n = 2, 4 n = 3), have been prepared and characterised. The progressive replacement of bpy by btz leads to blue-shifted UV-visible electronic absorption spectra, indicative of btz perturbation of the successively destabilised bpy-centred LUMO. For 4, a dramatic blue-shift relative to the absorption profile for 3 is observed, indicative of the much higher energy LUMO of the btz ligand over that of bpy, mirroring previously reported data on analogous ruthenium(II) complexes. Unlike the previously reported ruthenium systems, heteroleptic complexes 2 and 3 display intense emission in the far-red/near-infrared (λmax = 724 and 713 nm respectively in aerated acetonitrile at RT) as a consequence of higher lying, and hence less thermally accessible, 3MC states. This assertion is supported by ground state DFT calculations which show that the dσ* orbitals of 1 to 4 are destabilised by between 0.60 and 0.79 eV relative to their Ru(II) analogues. The homoleptic complex 4 appears to display extremely week room temperature emission, but on cooling to 77 K the complex exhibits highly intense blue emission with λmax 444 nm. As complexes 1 to 3 display room temperature luminescent emission and readily reversible Os(II)/(III) redox couples, light-emitting electrochemical cell (LEC) devices were fabricated. All LECs display electroluminescent emission in the deep-red/near-IR (λmax = 695 to 730 nm). Whilst devices based on 2 and 3 show inferior current density and luminance than LECs based on 1, the device utilising 3 shows the highest external quantum efficiency at 0.3 %

[Cu(bpy)(P^P)]+ containing light-emitting electrochemical cells: improving performance through simple substitution

Light-emitting electrochemical cells (LECs) containing [Cu(POP)(N^N)][PF6] (POP = bis(2-diphenylphosphinophenyl)ether, N^N = 6-methyl- or 6,6′-dimethyl-2,2′-bipyridine) exhibit luminance and efficiency surpassing previous copper(I)-containing LECs

Colour tuning by the ring roundabout : [Ir(C^N)2(N^N)]+ emitters with sulfonyl-substituted cyclometallating ligands

A series of cationic bis-cyclometallated iridium(III) complexes [Ir(C^N)2(N^N)]+ is reported. Cyclometallating C^N ligands are based on 2-phenylpyridine with electron-withdrawing sulfone substituents in the phenyl ring: 2-(4-methylsulfonylphenyl)pyridine (H1) and 2-(3-methylsulfonylphenyl)pyridine (H2). 2-(1HPyrazol- 1-yl)pyridine (pzpy) and 2-(3,5-dimethyl-1H-pyrazol-1-yl)pyridine (dmpzpy) are used as electronrich ancillary N^N ligands. The complexes have been fully characterized and the single crystal structure of [Ir(2)2(dmpzpy)][PF6]$MeCN has been determined. Depending on the position of the methylsulfonyl group, the complexes are green or blue emitters with vibrationally structured emission maxima at 491, 523 nm for [Ir(1)2(N^N)][PF6] or 463, 493 nm for [Ir(2)2(N^N)][PF6] in MeCN solution. The marked vibrational structure and the absence of a rigidochromic shift, together with theoretical predictions based on density functional theory calculations, confirm the 3LC nature of the emitting triplet state. All four complexes have relatively high photoluminescence quantum yields in de-aerated solution (53 to 77%). On going from solution to powder samples, the emission is red-shifted and the quantum yields are considerably lower (#11%). The complexes were tested in light-emitting electrochemical cells (LECs) achieving maximum luminances of 141 cd m2 when operated at 100 A m2 using pulsed current driving condition

Bright and stable light-emitting electrochemical cells based on an intramolecularly π-stacked, 2-naphthyl-substituted iridium complex

The synthesis and characterization of a new cationic bis-cyclometallated iridium(III) complex and its use in solid-state light-emitting electrochemical cells (LECs) are described. The complex [Ir(ppy)2(Naphbpy)][PF6], where Hppy = 2-phenylpyridine and Naphbpy = 6-(2-naphthyl)-2,2′-bipyridine, incorporates a pendant 2-naphthyl unit that π-stacks face-to-face with the adjacent ppy− ligand and acts as a peripheral bulky group. The complex presents a structureless emission centred around 595–600 nm both in solution and in thin film with relatively low photoluminescence quantum yields compared with analogous systems. Density functional theory calculations support the charge transfer character of the emitting triplet state and rationalize the low quantum yields in terms of a ligand-centred triplet localized on the 2-naphthyl unit that lies close in energy to the emitting state. LECs incorporating the [Ir(ppy)2(Naphbpy)][PF6] complex as the electroluminescent material are driven using a pulsed current operation mode and show high luminance, exceeding 300 cd m−2, and exceptional stabilities