Mechanistic Insights into Cobalt-Catalyzed Regioselective C4-Alkenylation of 3‑Acetylindole: A Detailed Theoretical Study

A detailed mechanistic study of Co­(III)-catalyzed C4-alkenylation of 3-acetylindole (1a) was done based on calculations at density functional theory (DFT) and correlated wave function levels. The whole catalytic cycle consists of four steps: C–H activation, olefin insertion, β-hydride elimination, and regeneration of the catalyst. The theoretical results support olefin insertion as the rate-determining step leading to the experimentally observed regioselectivity of the C4 site over the C2 site. By the analysis of three-dimensional (3D) geometries and the NCl plot, the preference for the C4 site over the C2 site could be attributed to the weaker repulsive interaction between the indole moiety and olefin in the transition states of the olefin insertion step for the former. The reliability of the theoretical mechanistic results is further confirmed through the DFT calculation of other related indole derivatives and olefin substrates

Difunctional Microelectrode Arrays for Single-Cell Electrical Stimulation and pH Detection

Due to its direct effect on biomolecules and cells, electrical stimulation (ES) is now widely used to regulate cell proliferation, differentiation, and neurostimulation and is even used in the clinic for pain relief, treatment of nerve damage, and muscle rehabilitation. Conventional ES is mostly studied on cell populations, but the heterogeneity of cancer cells results in the inability to access the response of individual cells to ES. Therefore, detecting the extracellular pH change (ΔpHe) after ES at the single-cell level is important for the application of ES in tumor therapy. In this study, cellular ΔpHe after periodic impulse electrostimulation (IES) was monitored in situ by using a polyaniline (PANI)-modified gold microelectrode array. The PANI sensor had excellent sensitivity (53.68 mV/pH) and linear correlation coefficient (R2 = 0.999) over the pH range of 5.55–7.41. The cells showed different degrees of ΔpHe after the IES with different intervals and stimulation potential. A shorter pulse interval and a higher stimulation potential could effectively enhance stimulation and increase cellular ΔpHe. At 0.5 V potential stimulation, the cellular ΔpHe increased with decreasing pulse interval. However, if the pulse interval was long enough, even at a higher potential of 0.7 V, there was no significant additional ΔpHe due to the insufficient stimulus strength. Based on the above conclusions, the prepared PANI microelectrode arrays (MEAs) were capable of stimulating and detecting single cells, which contributed to the deeper application of ES in tumor therapy

Effect of Ligands on Quantum Tunneling of Magnetization for Dysprosium <i>C</i>_4<i>v</i> Single-Molecule Magnets with Theoretical Insights

Two mononuclear DyIII-based compounds formulated as [Dy(L-pyra)2(NO3)(H2O)]2·3H2O (1) and [Dy(L-pyri)2(NO3)(CH3OH)] (2) (HL-pyra = N3-(2-pyrazinyl)-3-pyridinecarboxamidrazone; HL-pyri = N3-(2-pyridoyl)-3-pyridinecarboxamidrazone) have been synthesized by modifying the ligands with different functional groups. In two compounds, DyIII centers all feature on N4O5 in a spherical capped square-antiprismatic geometry with C4v configuration. The magnetic studies showed that 1 and 2 display single-molecule magnet (SMM) behavior under a zero dc field with energy barriers of 175.44 and 322.96 K, respectively. Such an apparent dereference in magnetic properties was interpreted via ab initio calculations. Theoretical results support the axial coordination to be the key factor responsible for the difference between compounds 1 and 2. This work highlights the coordination mode and axial Dy–O bond length as important factors in constructing a high-performance DyIII-based SMM

Theoretical and Experimental Studies of the Magnetostructural Correlations in Mononuclear Dy^III Compounds Evidenced by Quantum Tunneling of Magnetization Time, Crystal Field Parameters, and Point Charge Electrostatic Model

Three new mononuclear Dy­(III) compounds with a Schiff base ligand (H2L = N,N′-bis­(2-hydroxy-5-methyl-3-formylbenzyl)-N,N′-bis-(pyridin-2-ylmethyl)­ethylenediamine) and different β-diketonate co-ligands have been synthesized: [Dy­(L)­(tffb)] (1, tffb = 4,4,4-trifluoro-1-(2-furyl)-1,3-butanedione), [Dy­(L)­(fbta)] (2, fbta = 3-(4-fluorobenzoyl)-1,1,1-trifluoroacetone), and [Dy­(L)­(tta)] (3, tta = thenoyltrifluoroacetone). Compounds 1–3 exhibit distorted N4O4 trigonal dodecahedron configurations with different coordination substituents leading to various axial Dy–O bond lengths and O–Dy–O bond angles. The magnetization dynamics of compounds 1–3 are apparently different. Compound 1, showing the best single-molecule magnet (SMM) properties here, has the longest τQTM (0.357 × 10–2 s in theory vs 0.134 × 10–2 s in experiment) and an experimentally fitted Ueff of 94.76 K under a zero dc field. In 2 and 3, no reasonable Ueff could be fitted from the experimental data as no exponential dependence of τ on temperature is observed. This implies that the contribution of the Orbach pathway of 2 and 3 is even weaker than that of the Raman pathway. Both the accurate ab initio extraction and point charge electrostatic model show that 1 has the largest value of diagonal crystal field parameters, B20. This work verifies that the electronic structure of 1 is more suitable for SMM than 2 and 3

Macrocyclic Hexagonal Bipyramidal Dy(III)-Based Single-Molecule Magnets with a <i>D</i>_6<i>h</i> Symmetry

The design and synthesis of air-stable single-molecule magnets (SMMs) with large effective barriers of magnetic reversal and remarkably slow relaxation times are challenging. The design and synthesis of air-stable complexes with large effective magnetic reversal barriers and remarkably slow relaxation times are challenging in the field of SMMs. Herein, we present an air-stable hexagonal bipyramid [DyIII(bpyN4)(Ph3SiO)2](BPh4) (1) (bpyN4 = neutral hexaaza macrocyclic Schiff base ligand derived of 6,6′-diformyl-2,2′-bipyridyl and triethylenetetramine). The magnetic data demonstrate that the complex shows zero-field SMM behavior with magnetic hysteresis loops up to 13 K and an effective barrier of 584 K for 1. The experimental effective barrier is close to the energy of the first excited Kramers doublet (EKD1) obtained from ab initio calculations

Insight into the Mechanism of Single-Metal-Atom Tailoring on the Surface of Au–Cu Alloy Nanoclusters

Tailoring the surface structure of nanomaterials is desirable for investigating their mechanisms and properties from a nanochemistry perspective. The modification of the surface of metal nanoparticles with a single metal atom has proven difficult, which has hindered the understanding of the contribution of different motifs in nanoclusters to their properties. Herein, we report single-metal-atom surface tailoring by thermally etching the nanocluster AuxCu15–x(DPPMH)3(SPhCl2)9 (x = 8 or 9) to obtain AuxCu16–x(DPPMH)2(DPPM)­(SPhCl2)9 (x = 9 or 10) nanoclusters. An Au7Cu4 core was observed in both nanoclusters, which can be regarded as part of an icosahedron. Experiments and theoretical simulations revealed the tailoring processes of the icosahedron. Both nanoclusters displayed an NIR-II emission, and the introduction of the surface metal atom led to a red-shift in the emission band from 983 to 1025 nm. This work contributes to the development of precisely tailored nanocluster structures and provides an understanding of structure–property correlations

High-Throughput and Real-Time Monitoring of Single-Cell Extracellular pH Based on Polyaniline Microarrays

Real-time monitoring of extracellular pH (pHe) at the single-cell level is critical for elucidating the mechanisms of disease development and investigating drug effects, with particular importance in cancer cells. However, there are still some challenges for analyzing and measuring pHe due to the strong heterogeneity of cancer cells. Thus, it is necessary to develop a reliable method with good selectivity, reproducibility, and stability for achieving the pHe heterogeneity of cancer cells. In this paper, we report a high-throughput, real-time measuring technique based on polyaniline (PANI) microelectrode arrays for monitoring single-cell pHe. The PANI microelectrode array not only has a high sensitivity (57.22 mV/pH) ranging from pH 6.0 to 7.6 but also exhibits a high reliability (after washing, the PANI film was still smooth, dense, and with a sensitivity of 55.9 mV/pH). Our results demonstrated that the pHe of the cancer cell region is lower than that of the surrounding blank region, and pHe changes of different cancer cells exhibit significant cellular heterogeneity during cellular respiration and drug stimulation processes

Insight into the Mechanism of Single-Metal-Atom Tailoring on the Surface of Au–Cu Alloy Nanoclusters

Tailoring the surface structure of nanomaterials is desirable for investigating their mechanisms and properties from a nanochemistry perspective. The modification of the surface of metal nanoparticles with a single metal atom has proven difficult, which has hindered the understanding of the contribution of different motifs in nanoclusters to their properties. Herein, we report single-metal-atom surface tailoring by thermally etching the nanocluster AuxCu15–x(DPPMH)3(SPhCl2)9 (x = 8 or 9) to obtain AuxCu16–x(DPPMH)2(DPPM)­(SPhCl2)9 (x = 9 or 10) nanoclusters. An Au7Cu4 core was observed in both nanoclusters, which can be regarded as part of an icosahedron. Experiments and theoretical simulations revealed the tailoring processes of the icosahedron. Both nanoclusters displayed an NIR-II emission, and the introduction of the surface metal atom led to a red-shift in the emission band from 983 to 1025 nm. This work contributes to the development of precisely tailored nanocluster structures and provides an understanding of structure–property correlations

Att bygga läsning-om byggelevers förhållningssätt till läsning i svenskämnet på gymnasiet

This licentitate thesis is a study of Upper-Secondary School stu-dents’ approach towards reading fiction in the school subject of Swedish from a socio-cultural perspective. Furthermore, the social context and its importance for the students’ reading situation has been mapped. The students participating in the study are all first-graders and boys, studying the Construction Programme. The empirical material consists primarily of oral statements made by the students concerning their perception of how to read fiction in school. Using the construct of Pierre Bourdieu and with the reception model of Kathleen McCormick as a point of departure, the repertoirs of the students are described and analyzed. This study shows that the students bring different representa-tions of their group belonging, which effect their approach to rea-ding fiction. It also shows that the students’ idea of what a reader is and their own reading ability create their approach to reading. Ad-ditionally, the students have problems to see the actual purpose of reading fiction in a school situation. The results of the study show that in order to read fiction success-fully in a classroom situation, the school has to discuss and chal-lenge the students’ views of group belonging. Furthermore the school must improve when it comes to illustrating the more precise purpose and meaning of reading fiction in the school subject of Swedish. The study shows that because of the students’ different approa-ches to reading fiction, they tend to do two types of reading, one in-dividual and one for the school . In the latter, the students are incli-ned to limit their reading potential. And this is the real challenge for the subject of Swedish, but also ultimately the school, to challenge the students to use their full reading potential. Finally, the results of the study is discussed in relation to the new curriculum of the subject of Swedish, as it is presented in the sylla-bus ”Gy 11”. ”Gy 11” has been implemented since the autumn of 2011. Additionally, the consequences of the decreased number of hours for the subject of Swedish is considered. There are, however, stil good possibilities for the Swedish school to enable the students to reach their full reading potential in a class-room sitution

Differential performance between TOA and ovarian malignancy.

<p>Differential performance between TOA and ovarian malignancy.</p