Various Structural Design Modifications : para-Substituted Diphenylphosphinopyridine Bridged Cu(I) Complexes in Organic Light-Emitting Diodes

The well-known system of dinuclear Cu(I) complexes bridged by 2-(diphenylphosphino)pyridine (PyrPhos) derivatives Cu2X2L3 and Cu2X2LP2 (L = bridging ligand, P = ancillary ligand) goes along with endless variation options for tunability. In this work, the influence of substituents and modifications on the phosphine moiety of the NP-bridging ligand was investigated. In previous studies, the location of the lowest unoccupied molecular orbital (LUMO) of the copper complexes of the PyrPhos family was found to be located on the NP-bridging ligand and enabled color tuning in the whole visible spectrum. A multitude of dinuclear Cu(I) complexes based on the triple methylated 2- (bis (4-methylphenyl)phosphino)-4-methylpyridine (Cu-1b-H, Cu-1b-MeO, and Cu-1b-F) up to complexes bearing 2-(bis(4-fluorophenyl)phosphino)pyridine (Cu-6a-H) with electron-withdrawing fluorine atoms over many other variations on the NP-bridging ligands were synthesized. Almost all copper complexes were confirmed via single crystal X-ray diffraction analysis. Besides theoretical TDDFT-studies of the electronic properties and photophysical measurements, the majority of the phosphinomodified Cu(I) complexes was tested in solution-processed organic light-emitting diodes (OLEDs) with different heterostructure variations. The best results of the OLED devices were obtained with copper emitter Cu-lb-H in a stack architecture of ITO/PEDOT-PSS (50 nm)/poly-TPD (15 nm)/20 wt % Cu(I) emitter:CBP:TcTA(7:3) (45 nm)/TPBi (30 nm)/LiF(1 nm)/Al (>100 nm) with a high brightness of 5900 Cd/m(2) and a good current efficiency of 3.79 Cd/A.Peer reviewe

Investigation of Luminescent Triplet States in Tetranuclear Cu-I Complexes : Thermochromism and Structural Characterization

To develop new and flexible Cu-I containing luminescent substances, we extend our previous investigations on two metal-centered species to four metal-centered complexes. These complexes could be a basis for designing new organic light-emitting diode (OLED) relevant species. Both the synthesis and in-depth spectroscopic analysis, combined with high-level theoretical calculations are presented on a series of tetranuclear Cu-I complexes with a halide containing Cu4X4 core (X=iodide, bromide or chloride) and two 2-(diphenylphosphino)pyridine bridging ligands with a methyl group in para (4-Me) or ortho (6-Me) position of the pyridine ring. The structure of the electronic ground state is characterized by X-ray diffraction, NMR, and IR spectroscopy with the support of theoretical calculations. In contrast to the para system, the complexes with ortho-substituted bridging ligands show a remarkable and reversible temperature-dependent dual phosphorescence. Here, we combine for the first time the luminescence thermochromism with time-resolved FTIR spectroscopy. Thus, we receive experimental data on the structures of the two triplet states involved in the luminescence thermochromism. The transient IR spectra of the underlying triplet metal/halide-to-ligand charge transfer (M-3/XLCT) and cluster-centered ((CC)-C-3) states were obtained and interpreted by comparison with calculated vibrational spectra. The systematic and significant dependence of the bridging halides was analyzed.Peer reviewe

A novel carbazolophane : a comparison of the performance of two planar chiral CP-TADF emitters

Jürgen Manchot Foundation Deutsche Forschungsgemeinschaft. Grant Number: EXC-2082/1–390761711 China Scholarship Council. Grant Number: 202106310038 Engineering and Physical Sciences Research Council. Grant Numbers: EP/R035164/1, EP/W015137/1, EP/W524505/1 Helmholtz Association Program Ministère de l’Enseignement Supérieur et de la Recherche Centre National de la Recherche ScientifiqueThe prototypical example of a (cyclo)phane, [2.2]paracyclophane (PCP), has proven to be a versatile stereogenic moiety within the design of circularly polarized thermally activated delayed fluorescence (CP-TADF) emitters; however, the exploration of other cyclophanes within CP-TADF emitter design has been largely neglected. Here, a comparative study of the photophysical and optoelectronic properties of two cyclophane emitters, (1,7)tBuCzpPhTrz and its isomer (1,4)tBuCzpPhTrz, is presented. The carbazolophane-triazine compound (1,7)tBuCzpPhTrz, obtained via an unprecedented intramolecular rearrangement, is the first example of a planar chiral TADF emitter deviating from the PCP scaffold. Significant geometrical change of the enclosed carbazole in (1,7)tBuCzp results in an attenuation of the donor strength, while the merits of rigidity and steric bulk remain. In particular, the full width at half maximum (FWHM) of the photoluminescence spectrum in toluene of (1,7)tBuCzpPhTrz is reduced by 34% and blue-shifted by 20 nm compared to that of (1,4)tBuCzpPhTrz. In doped films, the compounds reach high photoluminescence quantum yields (ΦPL) of 91 and 81%, respectively. The chiroptical properties reveal dissymmetry factors |gPL| of up to 5 ? 10?4. These results demonstrate the impact of the cyclophane for the development of CP-TADF materials and add to the currently limited scope of available planar chiral donors.Peer reviewe

Highly soluble fluorine containing Cu(i) AlkylPyrPhos TADF complexes

Luminescent Cu(i) AlkylPyrPhos complexes with a butterfly-shaped Cu2I2 core and halogen containing ancillary ligands, with a special focus on fluorine, have been investigated in this study. These complexes show extremely high solubilities and a remarkable (photo)chemical stability in a series of solvents. A tunable emission resulting from thermally activated delayed fluorescence with high quantum yields was determined by luminescence and lifetime investigations in solvents and solids. Structures of the electronic ground states were analyzed by single crystal X-ray analysis. The structure of the lowest excited triplet state was determined by transient FTIR spectroscopy, in combination with quantum chemical calculations. With the obtained range of compounds we address the key requirement for the production of organic light emitting diodes based on solution processing.Peer reviewe

Functional Characterization of Cultured Keratinocytes after Acute Cutaneous Burn Injury

In addition to forming the epithelial barrier against the outside environment keratinocytes are immunologically active cells. In the treatment of severely burned skin, cryoconserved keratinocyte allografts gain in importance. It has been proposed that these allografts accelerate wound healing also due to the expression of a favourable--keratinocyte-derived--cytokine and growth factor milieu. In this study the morphology and cytokine expression profile of keratinocytes from skin after acute burn injury was compared to non-burned skin. Skin samples were obtained from patients after severe burn injury and healthy controls. Cells were cultured and secretion of selected inflammatory mediators was quantified using Bioplex Immunoassays. Immunohistochemistry was performed to analyse further functional and morphologic parameters. Histology revealed increased terminal differentiation of keratinocytes (CK10, CK11) in allografts from non-burned skin compared to a higher portion of proliferative cells (CK5, vimentin) in acute burn injury. Increased levels of IL-1α, IL-2, IL-4, IL-10, IFN-γ and TNFα could be detected in culture media of burn injury skin cultures. Both culture groups contained large amounts of IL-1RA. IL-6 and GM-CSF were increased during the first 15 days of culture of burned skin compared to control skin. Levels of VEGF, FGF-basic, TGF-ß und G-CSF were high in both but not significantly different. Cryoconservation led to a diminished mediator synthesis except for higher levels of intracellular IL-1α and IL-1ß. Skin allografts from non-burned skin show a different secretion pattern of keratinocyte-derived cytokines and inflammatory mediators compared to keratinocytes after burn injury. As these secreted molecules exert auto- and paracrine effects and subsequently contribute to healing and barrier restoration after acute burn injury therapies affecting this specific cytokine/growth factor micromilieu could be beneficial in burned patients

Antibodies used for immunohistochemical analyses.

<p>Antibodies used for immunohistochemical analyses.</p

Patient characteristics (n = 17).

<p>Randomly selected female patients who underwent breast reduction surgery served as a control population (n = 17; Age 37±7 years).</p

Time line and study design.

<p>Time line and study design.</p

Morphological characterization of keratinocytes from acute burn injury.

<p>H&E stainings revealed a significantly increased proportion of terminally differentiated cells (white arrows) in allogenic cultured epithelial grafts (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029942#pone-0029942-g002" target="_blank">Fig. 2A</a>) from breast reduction material in comparison to cells from autologous cultured epithelial grafts from burn patients (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029942#pone-0029942-g002" target="_blank">Fig. 2B</a>). In stainings with the monoclonal antibody KL-1 significantly more terminal differentiated keratinocytes in allogenic grafts (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029942#pone-0029942-g002" target="_blank">Fig. 2C</a>) were detected compared with autologous cultured epithelial grafts (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029942#pone-0029942-g002" target="_blank">Fig. 2D</a>). More vimentin-positive cells are present in autologous cultured epithelial grafts (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029942#pone-0029942-g002" target="_blank">Fig. 2F</a>) when compared to allogenic sheets (black arrows, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029942#pone-0029942-g002" target="_blank">Fig. 2E</a>).</p