Search results for "Phosphorescence"
showing 10 items of 101 documents
Bulky, Dendronized Iridium Complexes and their Photoluminescence
2019
Solution-processed blue emitters are essential for low-cost organic light-emitting diodes (OLEDs) but still face challenges due to their poor color purity, low efficiency and limited operational stability. Herein, by extending the conjugation of ultraviolet-emissive, facial tris(diphenylbenzimidazolyl)iridium (Ir) (fac-(dpbic)3Ir), we introduce two new types of solution-processed emitters, i.e. triisopropylsilylethynyl(TIPSE)-substituted fac-(dpbic)3Ir (2) and fac-(dpbic)3Ir-based polyphenylene dendrimers D1 and D2. The emissions of Ir-complex 2 and the dendrimers were successfully pushed toward a pure and sky blue color, respectively, due to the dominant 3π–π* nature of their emissive exci…
Iridium(III) Complexes with Phenyl-tetrazoles as Cyclometalating Ligands
2014
Ir(II) cationic complexes with cyclometalating tetrazolate ligands were prepared for the first time, following a two-step strategy based on (i) a silver-assisted cyclometalation reaction of a tetrazole derivative with IrCl3 affording a bis-cyclometalated solvato-complex P ([Ir(ptrz)(2)(CH3CN)(2)](+), Hptrz = 2-methyl-5-phenyl-2H-tetrazole); (ii) a substitution reaction with five neutral ancillary ligands to get [Ir(ptrz)(2)L](+), with L = 2,2'-bypiridine (1), 4,4'-di-tert-butyl-2,2'-bipyridine (2), 1,10-phenanthroline (3), and 2-(1-phenyl-1H-1,2,3-triazol-4-yl)pyridine (4), and [Ir(ptrz)(2)L-2](+), with L = tertbutyl isocyanide (5). X-ray crystal structures of P, 2, and 3 were solved. Elect…
Ship-in-a-Bottle Synthesis of a Large Guest Occupying Two Y Zeolite Neighbour Supercages: Characterisation and Photocatalytic Activity of the Encapsu…
2003
In a series of papers we reported the ship-in-a-bottle synthesis, photochemical properties and photocatalytic applications of 2,4,6-triphenylpyrylium cation (TP ) encapsulated inside the cavities of large pore zeolites Y and Beta. 2] The identity of encapsulated TP was then confirmed spectroscopically, particularly by the match of the IR spectra of the encapsulated organic material and that of the tetrafluoroborate solid of TP (TPBF4). In addition, the electrochemical response of zeolite Y encapsulated TP (TP@Y) consisted of a reversible single reduction process taking place at the same redox potential as that measured for TPBF4 solutions. Encapsulation of TP has a dramatic influence on its…
Ilgstošas fosforescences dizains karbazola atvasinājumos
2020
Ilgstošas fosforescences dizains karbazola atvasinājumos. Mazarevičs A., zinātniskie vadītāji Mg. chem. Leduskrasts K., Prof., Dr. chem. Sūna E. Bakalaura darbs, 62 lapaspuse, 55 attēli, 10 tabula, 42 literatūrās avoti, 4 pielikumi. Latviešu valodā. Literatūras apskatā analizēta luminiscence un fosforescence. Iekļauti organiskās fosforescences iegūšanas piemēri izmantojot kristalizāciju, smagā atoma efektu, starpmolekulāru un iekšmolekulāru mijiedarbību veidošanu kā arī nedalīta elektronu pāra vai karbonilgrupas ievadīšanu molekulā. Rezultātu izvērtējumā aprakstīta sintezēto savienojumu iegūšana, analizētas to luminiscentās īpašības, kā arī apskatīti rentgenstruktūras attēli no sintezētajie…
Xanthone-photosensitized detoxification of the veterinary anthelmintic fenbendazole
2013
Fenbendazole (1) is a common veterinary anthelmintic, toxic to water living microorganisms. Fluorescence quantum yields of 1 were found to be 0.11 in acetonitrile, 0.068 in methanol, 0.034 in cyclohexane, and 0.013 in water. The singlet excited state energy was ca. 96 kcal mol(-1) in all solvents. The phosphorescence spectrum of 1 in ethanol at 77 K displayed a maximum at 450 nm, leading to a triplet energy of 75 kcal mol(-1). Experimental excited state energies agree well with the results of OFT calculations at the time-dependent B3LYP/6-311+G(d,p)//B3LYP/6-31G(d) level. Laser flash photolysis (LFP) of 1 at 266 nm led to transients absorbing in the 300-700 nm range, ascribed to radical cat…
Near-IR to Near-IR Upconversion Luminescence in Molecular Chromium Ytterbium Salts
2020
Abstract Upconversion photoluminescence in hetero‐oligonuclear metal complex architectures featuring organic ligands is an interesting but still rarely observed phenomenon, despite its great potential from a basic research and application perspective. In this context, a new photonic material consisting of molecular chromium(III) and ytterbium(III) complex ions was developed that exhibits excitation‐power density‐dependent cooperative sensitization of the chromium‐centered 2E/2T1 phosphorescence at approximately 775 nm after excitation of the ytterbium band 2F7/2→2F5/2 at approximately 980 nm in the solid state at ambient temperature. The upconversion process is insensitive to atmospheric ox…
Structure and luminescence properties of supramolecular polymers of amphiphilic aromatic thioether–peptide conjugates in water
2019
We present the preparation of luminophore–peptide conjugates that self-assemble into supramolecular polymers in neutral buffer. To this end, we have prepared a small library of six conjugates with varying substitution patterns of the aromatic thioethers, as well as varying amino acid sequences. The latter have allowed us to tune the thermodynamic driving force for self-assembly and probe their photoluminescent properties either in the monomeric or polymeric state, while fully avoiding selective solvent techniques or organic solvent mixtures. All of the supramolecular structures were characterised with transmission electron microscopy, circular dichroism measurements, as well as steady-state…
Red-light-emitting electrochemical cell using a polypyridyl iridium(III) polymer.
2009
A deep-red phosphorescent ionic iridium(III) complex is prepared and incorporated into a polymer. Both the complex (1) and the polymer (2) were used as the single active material in solid-state light-emitting electrochemical cells (LECs). The devices built up using 1 and 2 emit in the deep-red region of the visible spectrum with CIE coordinates x = 0.710; y = 0.283 and x = 0.691; y = 0.289, respectively, making them one of the deepest-red emitting LECs reported. It is the first example of a polymeric LEC incorporating an ionic iridium complex, which exhibits increased stabilities compared with the device based on the small molecular weight complex.
Combined thermal evaporated and solution processed organic light emitting diodes
2011
Abstract Highly efficient, partly solution processed phosphorescent red, green and white organic light emitting diodes with small molecular weight host materials are prepared from commercially available starting compounds. Starting from an evaporated reference device, layers are stepwise replaced by solution processed layers. Replacing the evaporated hole transport layer by a solution processed polymer interlayer does not affect the performance and allows spincoating of the emissive layer after annealing of the polymer. Devices with, next to the spincoated hole injection and transport layer, a solution processed emission layer show similar characteristics and efficiencies as the reference d…
Ionic iridium complex and conjugated polymer used to solution-process a bilayer white light-emitting diode.
2013
Bilayer white light-emitting devices are prepared from solution, using an ionic orange phosphorescent organometallic complex and a neutral fluorescent conjugated polymer. Because of the very different polarity of the two components, they dissolve in orthogonal solvents, allowing for the direct deposition of the blue emitter on top of the orange emitter without the need of cross-linking or special coating methodology. Fine tuning of the layer thickness of both light-emitting layers allows for the color tuning of different types of white light.