How the Quantum Efficiency of a Highly Emissive Binuclear Copper Complex Is Enhanced by Changing the Processing Solvent

Polymorphism is often linked to the choice of processing solvents. Packing effects or the preference of one certain conformer as possible causes of this phenomenon are strongly dependent on solvents and especially on their polarity. Even in amorphous solids, the microstructure can be controlled by the choice of solvents. Polymorphs or amorphous solids featuring different packing densities can exhibit different properties in terms of stability or optical effects. The influence of these effects on a binuclear, strongly luminescent copper­(I) complex was investigated. Many possible applications for luminescent, amorphous coordination compounds, such as organic light-emitting diodes, sensors, and organic lasers, rely on photophysical properties like quantum efficiency to be repeatable. The effect of processing solvents in this context is often underestimated, but very relevant for utilization in device manufacturing and should therefore be understood more deeply. In this work, theoretical derivations, DFT calculations, X-ray-diffraction, photoluminescence spectroscopy, and the time-dependent single-photon-counting-technique (TDSPC) were used to understand this phenomenon more deeply. The influence of five different solvents on Cu₂I₂(MePyrPHOS)₃ was probed. This resulted in a modulation of the photoluminescence quantum yield ϕ between 0.5 and 0.9 in amorphous solid state. A new polymorph of the material with slightly reduced values for ϕ has been identified. The reduced efficiency could be correlated with a higher porosity and a reduced packing density. Dense packing reduces nonradiative decay by geometrical fixation and thus increases the quantum efficiency. The existence of similar effects on aluminum and iridium compounds has been confirmed by application of different processing solvents on Alq₃ and Ir­(ppy)₃. These results show that a tuning of the efficiency of a emissive metal complexes by choosing a proper processing solvent is possible. If highly efficient materials for practical applications are desired, an evaluation of multiple solvents has to be considered

Copper(I) Complexes Based on Five-Membered P^∧N Heterocycles: Structural Diversity Linked to Exciting Luminescence Properties

Bridging P^∧N ligands bearing five-membered heterocyclic moieties such as tetrazoles, 1,2,4-triazoles, oxadiazoles, thiadiazoles, and oxazoles have been investigated regarding their complexation behavior with copper­(I) iodide as metal salts. Different complex structures were found, depending either on the ligand itself or on the ligand-to-metal ratios used in the complexation reaction. Two different kinds of luminescent dinuclear complex structures and a kind of tetranuclear complex structure were revealed by X-ray single-crystal analyses and were further investigated for their photophysical properties. The emission maxima of these complexes are in the blue to yellow region of the visible spectrum for the dinuclear complexes and in the yellow to orange region for the tetranuclear complexes. Further investigations using density functional theory (DFT) show that the highest occupied molecular orbital (HOMO) is located mainly on the metal halide cores, while the lowest unoccupied molecular orbital (LUMO) resides mostly in the ligand sphere of the complexes. The emission properties were further examined in different environments such as neat powders, neat films, PMMA matrices, or dichloromethane solutions, revealing the high potential of these complexes for their application in organic light-emitting diodes. Especially complexes with 1,2,4-triazole moieties feature emission maxima in the blue region of the visible spectrum and quantum yields up to 95% together with short decay times of about 1–4 μs and are therefore promising candidates for blue-emitting materials in OLEDs

Newborn characteristics.

BackgroundWe are obliged to give babies the chance to profit from a nationwide screening of developmental dysplasia of the hip in very rural areas of Mongolia, where trained physicians are scarce. This study aimed to compare the quality and interpretation of hip ultrasound screening examinations performed by nurses and junior physicians.MethodsA group of 6 nurses and 6 junior physician volunteers with no previous ultrasound experience underwent Graf’s standard training in hands-on practice. Newborns were examined before discharge from the hospital, according to the national guideline. Two standard documentation images of each hip were saved digitally. The groups were compared on the proportion of good quality of sonograms and correct interpretation. Two Swiss supervisors’ agreed diagnosis according to Graf was considered the final reference for the study purposes.ResultsA total of 201 newborns (402 hips or 804 sonograms) were examined in the study, with a mean age of 1.3±0.8 days at examination. Junior physicians examined 100 newborns (200 hips or 400 sonograms), while nurses examined 101 newborns (202 hips or 404 sonograms). The study subjects of the two groups were well balanced for the distribution of baseline characteristics. The study observed no statistically significant difference in the quality of Graf’s standard plane images between the providers. Eventually, 92.0% (92) of the physician group and 89.1% (90) of the nurse group were correctly diagnosed as “Group A” (Graf’s Type 1 hip) or “Non-Group A” hips (p = 0.484). The most common errors among the groups were a missing lower limb, wrong measurement lines, and technical problems.ConclusionOur study provides evidence that while there might be a trend of slightly more technical mistakes in the nurse group, the overall diagnosis accuracy is similar to junior physicians after receiving standard training in Graf’s hip ultrasound method. However, after basic training, regular quality control is a must and all participants should receive refresher trainings. More specifically, nurses need training in the identification of anatomical structures.</div

Comparison of quality and interpretation of newborn ultrasound screening examinations for developmental dysplasia of the hip by nurses and junior physicians.

Comparison of quality and interpretation of newborn ultrasound screening examinations for developmental dysplasia of the hip by nurses and junior physicians.</p

Univariate analysis of demographic and hip ultrasound examination characteristics of correct and incorrect diagnosis.

Univariate analysis of demographic and hip ultrasound examination characteristics of correct and incorrect diagnosis.</p

Hip ultrasound examination performance of the nurses’s and junior physicians‘ groups.

Hip ultrasound examination performance of the nurses’s and junior physicians‘ groups.</p

Copper(I) Complexes Based on Five-Membered P^∧N Heterocycles: Structural Diversity Linked to Exciting Luminescence Properties

Bridging P^∧N ligands bearing five-membered heterocyclic moieties such as tetrazoles, 1,2,4-triazoles, oxadiazoles, thiadiazoles, and oxazoles have been investigated regarding their complexation behavior with copper­(I) iodide as metal salts. Different complex structures were found, depending either on the ligand itself or on the ligand-to-metal ratios used in the complexation reaction. Two different kinds of luminescent dinuclear complex structures and a kind of tetranuclear complex structure were revealed by X-ray single-crystal analyses and were further investigated for their photophysical properties. The emission maxima of these complexes are in the blue to yellow region of the visible spectrum for the dinuclear complexes and in the yellow to orange region for the tetranuclear complexes. Further investigations using density functional theory (DFT) show that the highest occupied molecular orbital (HOMO) is located mainly on the metal halide cores, while the lowest unoccupied molecular orbital (LUMO) resides mostly in the ligand sphere of the complexes. The emission properties were further examined in different environments such as neat powders, neat films, PMMA matrices, or dichloromethane solutions, revealing the high potential of these complexes for their application in organic light-emitting diodes. Especially complexes with 1,2,4-triazole moieties feature emission maxima in the blue region of the visible spectrum and quantum yields up to 95% together with short decay times of about 1–4 μs and are therefore promising candidates for blue-emitting materials in OLEDs

A hip sonogram.

A. Three landmarks of the standard plane. 1. Standard cut (red arrow), 2. Lower limb or the bottom of the acetabulum (yellow circle), 3. Acetabular labrum and the lateral edge of the acetabulum (blue circle). B. Hip is evaluated by measuring two angles formed by three lines drawn from three landmarks. 1. Basic line (red), 2. Bony roof line (blue), 3. Cartilaginous roof line (yellow).</p

Comparison of Graf types and ABCD groups for hip ultrasound.

Comparison of Graf types and ABCD groups for hip ultrasound.</p

Sorption of Silver Nanoparticles to Environmental and Model Surfaces

The fate of engineered nanoparticles in environmental systems is controlled by changes in colloidal stability and their interaction with different environmental surfaces. Little is known about nanoparticle–surface interactions on the basis of sorption isotherms under quasi-equilibrium conditions, although sorption isotherms are a valuable means of studying sorbate-sorbent interactions. We tested the extent to which the sorption of engineered silver nanoparticles (<i>n</i>Ag) from stable and unstable suspensions to model (sorbents with specific chemical functional groups) and environmental (plant leaves and sand) surfaces can be described by classical sorption isotherms. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) qualitative and quantitative analyses were also used to assess the morphology and nanomechanical parameters of the covered surfaces. The sorption of <i>n</i>Ag from stable suspensions was nonlinear and best described by the Langmuir isotherm. Langmuir coefficients varied with sorbent surface chemistry. For <i>n</i>Ag sorption from an unstable suspension, the sorption isotherms did not follow any classical sorption models, suggesting interplay between aggregation and sorption. The validity of the Langmuir isotherm suggests monolayer sorption, which can be explained by the blocking effect due to electrostatic repulsion of individual nanoparticles. In unstable suspensions, aggregates are instead formed in suspension and then sorbed, formed on the surface itself, or formed in both ways