Side Arms Research Articles

Palladium(II) NCS‐Pincer Complexes Mediated Regioselective Cross Dehydrogenative Alkenation of 2‐Arylthiophenes

AbstractIn this report, we have synthesized two new NCS pincer ligands by the Schiff base reaction of 3‐((phenylthio)methoxy)benzaldehyde (P) with alkyl amines (tbutylamine (L1) and 1‐adamantylamine (L2)). The palladium pincer complexes (tbutylamine=C1 and 1‐adamantylamine=C2) of these ligands were synthesized by their reaction with PdCl2(CH3CN)2 precursor. The newly synthesized ligands and complexes were characterized using various analytical and spectroscopic techniques such as 1H, 13C{1H} Nuclear Magnetic Resonance (NMR), Ultraviolet–visible (UV‐Visible), Fourier Transform Infrared (FTIR) Spectroscopy, and High‐Resolution Mass Spectrometry (HRMS). The structure of the ligand and its coordination mode with palladium precursor were studied with the help of single‐crystal X‐ray diffraction. The complexes showed distorted square planar geometry around the palladium center. The palladium pincer complexes were used as catalysts for the regioselective cross‐dehydrogenative alkenation of 2‐arylthiophene derivatives. The complex C2, where sterically bulky adamantyl ligand is part of the side arm showed a higher yield of alkenation reaction. Only 2.5 mol% catalyst loading was sufficient to achieve 74–95 % yields of desired products with excellent functional group tolerance under mild reaction conditions. The poisoning experiments (PPh3 and Hg) showed the homogeneous nature of the catalytic process. The plausible mechanism of the reaction was proposed based on the control experiments and time‐dependent HRMS studies.

Increasing Ligand Denticity and Stability for a Water Oxidation Electrocatalyst using P(V) as Connecting Element

AbstractCarboxylate complexes have risen to prominence in the field of water oxidation catalysis. Here for the first time we use the higher valence of phosphinates [P(V)] relative to that of carboxylates [C(IV)] to increase ligand denticity. We describe the synthesis and characterization of a new dianionic pentadentate ligand, bcpq2− that contains a tridentate 2,2’‐bipyridine‐6‐carboxylato moiety, in addition to a 6’‐phosphinato substituent that acts as fourth ligand and bears a side arm containing a quinoline, the fifth ligand. The new bcpq ligand allows formation of [Ru(II)(bcpq)(L)] (2 a–b, L=picoline or isoquinoline) and in preliminary results, of a Co(II) complex. NMR spectroscopy, X‐ray diffraction, cyclic voltammetry, differential pulse and square wave voltammetry were used to characterize 2 a–b, with 2 b being characterized more extensively as a catalyst. Bulk electrolysis over 15 h at pH 7 was also used, showing that 2 b gave 100±5 % faradaic efficiency and remained completely homogeneous, whereas 1 b was no longer homogeneous; this comparison conclusively shows the advantage of the added denticity in the electrocatalytic context. Replacing carboxylate with P(V) phosphinate with an added arm may be used in other ligand systems to enhance the durability of homogeneous catalysts.

Three-Component Radical Cross-Coupling: Asymmetric Vicinal Sulfonyl-Esterification of Alkenes Involving Sulfur Dioxide.

A novel catalytic system for radical cross-coupling reactions based on copper and chiral Pyridyl-bis(imidazole) (PyBim) ligandsis described. It overcomes the challenges of chemoselectivity and enantioselectivity, achieving a highly enantioselective vicinal sulfonyl-esterification reaction of alkenes involving sulfur dioxide. This strategy involves the use of earth-abundant metal catalyst, mild reaction conditions, a broad range of substrates (84 examples), high yields (up to 97% yield), and exceptional control over enantioselectivity. The reaction system is compatible with different types of radical precursors, including O-acylhydroxylamines, cycloketone oxime esters, aryldiazonium salts, and drug molecules. Chiral ligand PyBim is identified as particularly effective in achieving the desired high enantioselectivity. Mechanistic studies reveal that copper/PyBim system plays a vital role in C─O coupling, employing an outer-sphere model. In addition, the side arm effect of ligand is observed.

The impact of embedment of the side arms of 52 mg levonorgestrel-intrauterine device on bleeding and pain: A prospective cohort study

PurposeThe purpose of this study was to analyse the impact of embedment of side arms of the levonorgestrel 52 mg intrauterine device (LNG-IUD) in the myometrium (assessed by three-dimensional transvaginal ultrasound (3D-TVUS)) on uterine bleeding and pain. Materials and methodsWe performed a prospective cohort study in a large Dutch teaching hospital between February 2015 and December 2016. Participants over 18 years of age who selected a LNG-IUD for contraception or because of heavy menstrual bleeding were eligible for inclusion. Six weeks after insertion, a 3D-TVUS was performed to diagnose embedment of the side arms. At that moment participants filled in questionnaires about their bleeding pattern and pelvic pain. Menstruation patterns ‘no bleeding’, ‘regular menstruation’, ‘sometimes a day of spotting (maximum once a week)’ were classified as favourable bleeding pattern. Menstruation patterns ‘heavy menstrual bleeding’, ‘several days a week bleeding days’, ‘several days a week spotting days’, ‘continuously spotting’, and ‘completely irregular cycle’ were classified as unfavourable bleeding pattern. Univariate and multivariate logistic regression analysis was used to calculate odds ratios (OR) and 95 %-confidence intervals (CI). The multivariate analysis included endometrial thickness, reason for insertion and parity. The analysis of pelvic pain additionally included previous insertion. ResultsA total of 220 participants were evaluated for the study of whom 176 returned the questionnaires. Embedment of the side arms was observed in 43 of the 176 responding participants (24.4 %). Favourable bleeding pattern was reported by 25/43 (58.1 %) participants with embedment and 53/133 (39.8 %) participants without embedment (ORadj 1.8, 95 % CI 0.9–3.9). Pelvic pain was reported by 4/43 (9.3 %) participants with embedment and 24/133 (18.1 %) participants without embedment (ORadj 0.3; CI 0.1–1.2). ConclusionsThe present study suggests that embedment of the side arms of the LNG-IUD in the myometrium assessed by 3D-TVUS is not associated with a unfavourable bleeding pattern nor pelvic pain six weeks after insertion. From this point of view, we do not recommend to perform standard 3D-TVUS for the purpose of excluding or demonstrating embedment.

Manganese‐Mediated Synthesis of NHC‐Phosphine Ligand Precursors

AbstractAlkylation of N‐substituted imidazoles ImR’ (R’=2,4,6‐trimethylphenyl, 2,6‐diisopropylphenyl, 1‐adamantyl) with Mn(I) methylenephosphonium complexes [Cp(CO)2Mn(η2‐P,C‐R2P=C(H)Ph)](BF4) (PR2=PPh2, PCy2, trans‐PC(H)PhCH2CH2C (H)Ph) followed by photochemical demetallation afforded a series of bidentate NHC‐phosphine ligand precursors [R2PC(H)PhImR’](BF4) in moderate to good yield. The same strategy was successfully applied to N‐functionalized imidazoles ImL (L=2‐pyridyl, CH2SMe, CH2ImMe) to afford selectively NHC core pincer pre‐ligands featuring phosphine/thioether, phosphine/NHC and phosphine/pyridine side arms. For PCy2 derivatives, free NHCs in both bidentate and pincer series generated by deprotonation of the corresponding cationic precursors were shown to be persistent at room temperature.

Spectroscopic Rationalization of Selective Colorimetric Chemosensing of Fe(lll) in Aqueous Medium by a New Mono-Substituted Dibenzodiaza-Crown Ether Macrocyclic Ligand Appended with Mono 2-Benzimidazole N-Pendant Side Arm.

Optical chemosensor L comprising of a new mono-N-substituted derivative of dibenzodiaza-crown ether macrocyclic ligand bearing a 2-benzimidazole (2Bim) side arm was synthesized, and characterized by FT-IR, elemental microanalyses, 1H NMR, and 13C NMR, UV-visible, fluorescence (FL) spectroscopy. The colorimetric chemosensing behavior of L toward the library metal ions was examined, wherein L represented a prompt and selective yellow-to-purple color change for Fe(III) cation in a 25µM solution with LOD as 0.23 µM in ethanol:water (9:1, v/v), even in the presence of the other library metal ions (LMI). Based on the 1H NMR, UV-visible, and FL observations the coordination sphere of Fe(III) was shared with two 2-benzoimidazole (2Bim) side arms which were also confirmed by the elemental microanalyses (in the solid state) and the Job plot method (in the solution) of the complex. Moreover, the above-mentioned color change was attributed to the presence of a strong charge transfer (LMCT) band for the Fe(III)/L interaction in the solution. Furthermore, the viscosity measurement in the presence of Fe(III) uncovered an increase at 0.5-1.0 ratios for Fe(III)/L, attributable to the formation of a self-assembly in the solution. A TLC paper strip was impregnated by L for selective detection of Fe(III), demonstrating a live color change for Fe(III) at 0-5 mM in the presence of LMI.

Modeling Dendrite Coarsening and Remelting during Directional Solidification of Al-06wt.%Cu Alloy.

Research efforts have been dedicated to predicting microstructural evolution during solidification processes. The main secondary arm spacing controls the mushy zone's permeability. The aim of the current work was to build a simple sub-grid model that describes the growth and coarsening of secondary side dendrite arms. The idea was to reduce the complexity of the curvature distribution with only two adjacent side arms in concurrence. The model was built and applied to the directional solidification of Al-06wt%Cu alloy in a Bridgman experiment. The model showed its effectiveness in predicting coarsening phenomena during the solidification of Al-06wt%Cu alloy. The results showed a rapid growth of both arms at an earlier stage of solidification, followed by the remelting of the smaller arm. In addition, the results are in good agreement with an available time-dependent expression which covers the growth and coarsening. Such model can be implemented as a sub-grid model in volume average models for the prediction of the evolution of the main secondary arms spacing during macroscopic solidification processes.

Dynamic control of circumrotation of a [2]catenane by acid-base switching.

Dynamic control of the motion in a catenane remains a big challenge as it requires precise design and sophisticated well-organized structures. This paper reports the design and synthesis of a donor-acceptor [2]catenane through mechanical interlocking, employing a crown ether featuring two dibenzylammonium salts on its side arms as the host and a cyclobis(paraquat-p-phenylene) (CBPQT ⋅ 4PF6) ring as the guest molecule. By addition of external acid or base, the catenane can form self-complexed or decomplexed compounds to alter the cavity size of the crown ether ring, consequently affecting circumrotation rate of CBPQT ⋅ 4PF6 ring of the catenane. This study offers insights for the design and exploration of artificial molecular machines with intricate cascading responsive mechanisms.

Hyperstretching in elongational flow of densely grafted comb and branch-on-branch model polystyrenes

Strain hardening of long-chain branched polymers in elongational flow occurs due to the stretch of the backbone chain between branch points. With an increasing number of side arms, the length of the backbone chain segment between two branch points of a comb decreases. Of particular interest is the case when the number Nb of arms per entanglement length of the polymer is larger than one. This leads not only to larger strain hardening but also to hyperstretching, i.e., the elongational stress growth shows an enhanced increase with strain. We consider elongational data reported by Abbasi et al. [Macromolecules 50(15), 5964–5977 (2017)] and Faust et al. [Macromol. Chem. Phys. 224(1), 2200214 (2023)] on a series of comb and branch-on-branch polystyrene (PS) melts with the average number Nb of branches per entanglement segment of the backbone ranging from Nb = 0.2 to Nb = 9.5. In addition, we present measurements of the elongational viscosity of two PS combs with Nb = 4.7 as well as of blends consisting of 5 to 50 wt. % of a PS comb and a monodisperse linear PS. Analysis by the hierarchical multimode molecular stress function model shows that while backbone chains of loosely grafted combs with Nb < 1 are stretched affinely in elongational flow, backbone chains of more densely grafted combs with Nb > 1 show increasing hyperstretching with increasing Nb. The elongational data of the comb/linear blends confirm that hyperstretching is an intrinsic property of the comb macromolecule with Nb > 1, independent of its concentration in the blend. While this is of considerable interest from a modeling point of view, hyperstretching causing an enhanced increase of the elongational stress growth can also have a significant impact on the processability of polymers, and quantification of this effect is, therefore, important.

A target-triggered mimic nucleic acid enzyme enables versatile and sequence-independent biosensing

Simultaneous quantification of multiple microRNAs (miRNAs) is very important because lots of pathologies are associated with abnormal expressions of several miRNAs. In this work, we proposed an enzyme-assisted cleavage of nucleic acids signal amplification (TMNAE enzyme sensing) based method enable simple, highly sensitive and selective multiple miRNAs detection. Two unmodified probes and analyte were assembled into a Y-shaped structure that contains a nicking endonuclease recognition site in the complementary region of the unmodified probe and two side arms complementary to reporter probe. Thus, it enables the loading of a Nicking endonuclease (NEase) on the complementary region of the unmodified probe, localization to a specific locus through hybridization of the side arms with reporter probe, and cleavage thereof. NEase is employed to recycle the process of Y-shaped structure assisted digestion of reporter probe, thus, resulting in a significant fluorescence signal amplification through which one analyte molecule cleaves thousands of reporter probe molecules. We demonstrate the efficiency of this TMNAE enzyme sensing strategy for rapid direct quantification of multiple sequence specific miRNAs in homogeneous solution with the detection limit in the femtomolar range, nearly 4 orders of magnitude lower than that of conventional hybridization assay methods. This assay also has the ability to discriminate the target from other miRNAs or even single-base mismatched sequences. Moreover, the TMNAE enzyme sensing strategy can be used to detect other molecules apart from nucleic acids. The detection of thrombin in biological samples showed a LOD of as low as 1 nM. Overall, our proposed TMNAE enzyme sensing strategy provides a versatile, reliable, simple, highly sensitive, and selective detection method and shows promising application in molecular disease diagnosis and biomedicine.

Ligand redox controlled amine dehydrogenation and imine hemilability in singlet diradical azo-aromatic Ni(II) complexes: characterization of the electron transfer series of azo-imine complexes of Ni(II).

Herein, using azo-amine (H2L) and azo-imine (L1-3) ligands, singlet diradical Ni(II) complexes [1] and [2] were synthesized from Ni(0)(COD)2 in THF. In separate reactions, homoleptic NiII complexes, [3a]2+-[3c]2+, were synthesized from [NiII(H2O)6](ClO4)2 and L1-3, respectively. All these complexes were characterized thoroughly. The X-ray structures of [1] and [2] showed that the amine side arm in [1] and the imine side arm in [2] are de-coordinated. The dN-N lengths in these two complexes were found to be ∼1.32 Å, which corresponds to the one-electron reduced azo-bond length. These complexes, [1] and [2], showed 1H NMR signals characteristic of diamagnetic compounds. These studies, along with DFT calculations, indicated that the unpaired spins on ligands coupled antiferromagnetically with the two unpaired spins on NiII to result in s = 0 ground states. Complex [1] showed ligand-based redox-induced dehydrogenation of the distal amine side arm to result in L1. Complexes [3a]2+-[3c]2+ have dN-N lengths of ∼1.27 Å and dC-N lengths of ∼1.28 Å. In cyclic voltammetry, complex [3a]2+ showed four well-resolved reversible reductive waves at 0.5 V to -1.6 V in dichloromethane. The first two waves became irreversible when they were measured in acetonitrile solution. The electron transfer series of [3a]2+ was further characterized by spectro-electrochemistry, EPR, and DFT calculations. These showed that all the reductions were associated with the ligand. It was further probed by redox events in complexes [3b]2+ and [3c]2+. While the electron donor -OMe group on the phenyl ring of the azo moiety in [3b]2+ showed a prominent cathodic shift of the potentials, the -F substitution on the phenyl group on the imine side arm of [3c]2+ has almost no effect. It has to be noted here that the oxidation of [2] by two electrons returns it back to complex [3a]2+. Reduction of [3a]2+ by two electrons also resulted in complex [2], indicating reversible ligand redox-induced hemilability of the imine moiety between [3a]2+ and [2]. Moreover, characterization of the electron transfer series of [3a]2+ and [2] has shown superior redox non-innocent behaviour and coordination ability of the azo-pyridine moiety in nickel(II) complexes over the imino-pyridine moiety of the ligand.

A new biphenol-dipicolylamine based ligand and its dinuclear Zn2+ complex as fluorescent sensors for ibuprofen and ketoprofen in aqueous solution.

In this work, the study of the new ligand 3,3'-bis[N,N-bis(pyridine-2-ylmethyl)aminomethyl]-2,2'-dihydroxybiphenyl (L) is reported, where a central 2,2'-biphenol (BPH) fluorophore was functionalized at 3,3'-positions with two dipicolylamine (DPA) side arms as receptor units. Following the synthesis and full chemical-physical characterization, the acid-base and Zn2+-coordination abilities of L were investigated through a combination of potentiometric, UV-Vis, fluorescence, NMR, XRD and DFT measurements. The optical properties of the ligand turned out to be strongly dependent on the pH, being straightforwardly associated with the protonation state of the BPH moiety, whereas its peculiar design allowed to form stable mono and dinuclear Zn2+ complexes. In the latter species, the presence of two Zn2+ ions coordinatively unsaturated and placed at close distance to each other, prompted us to test their usefulness as metallo-receptors for two environmental pollutants of great relevance, ibuprofen and ketoprofen. Potentiometric and fluorescence investigations evidenced that these important non-steroidal anti-inflammatory drugs (NSAIDs) are effectively coordinated by the metallo-receptors and, of relevance, both the stability and the fluorescence properties of the resulting ternary adducts are markedly affected by the different chemical architectures of the two substrates. This study aims at highlighting the promising perspectives arising from the use of polyamino phenolic ligands as chemosensors for H+/Zn2+ and other additional anionic targets in their metal-complexed forms.

Converging optical and electrochemical detection strategies for multimodal hydrazine sensing: insights into substituent-driven diverse response.

A pair of pyrene-based chalcogen derivatives have been developed, which demonstrate multimodal ratiometric response towards hydrazine. Although these probes share a common pyrene core and differ primarily in the electronic nature of their terminal side arms, they display distinct photophysical properties. Notably, both probes undergo significant spectral changes upon the addition of hydrazine, but probe 1 exhibits a more pronounced interaction (∼5-fold fluorescence enhancement) than probe 2, attributed to the higher level of aggregation in probe 2, rendering the binding site less accessible to the incoming analyte. Additionally, we have explored electrochemical techniques, including cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), for hydrazine detection. Our molecular design strategy relies on ratiometric-responsive specific cyclization triggered by hydrazine, leading to the disruption of the π-conjugated system and the subsequent suppression of intramolecular charge transfer (ICT) processes, along with dis-assembly of the aggregated probe molecules. These probes enable the nakеd-eye detection of hydrazine, with a low detection limit of 7.33 ppb and 7.58 ppb for probe 1 and 2, respectively. Furthermore, we have investigated cost-effective probe-coatеd paper strips for the detection of hydrazine in water.

Beyond conventional Brønsted acid catalysis: leveraging the impact of charged moiety on the phenol for the construction of julolidine units

ETP demonstrated efficient catalytic activity for the formation of the julolidine ring. NMR and kinetic investigations showed the significant influence of the charged side arm on phenol over the rate of formation of the julolidine.

Исследование аэрогазодинамических процессов переноса радона из горных массивов

Introduction. Drying tailings are a source of gaseous chemicals, in particular radon222, which is carried by air currents along the slopes of the gorge. These processes need constant monitoring. Purpose of research. Establishment of climatic conditions most influencing the measurements of mountain radon and its dispersion in the atmosphere. Research methods and materials. The data of weather stations located in the Alagir mountain gorge and the data of the mathematical model of this gorge were used to establish the characteristic wind roses at the points of the gorge selected for field measurements of mountain radon. Research results. It has been established that at the nearby points of the mountain gorge, the prevailing direction and strength of the wind can differ significantly. The differences depend on the landscape features of the surface of the slopes of the mountain gorge. This factor determines the direction of migration of chemical elements and decay products of mountain radon. This conclusion is confirmed by direct measurement of wind speed at two points in the gorge, as well as by the results of mathematical modeling. Discussion of research results. A preliminary calculation of the passive impurity concentration field within the mountain gorge shows the most characteristic places on the slopes of the gorge from the point of view of measurements. Preliminary algorithm for choosing the location of measurements. Determination of 210Pb content in natural «traps» or sediments can determine the migration paths of «mountain» radon and estimate the magnitude of its interaction with the nature of the gorge, subject to the following assumptions: 1) certain sampling sites are not subject to significant seasonal disturbances; 2) natural and climatic conditions, especially the amount of precipitation, in the studied gorge should not have abnormal changes before sampling; 3) sampling should preferably be carried out in autumn on fallen leaves in hollows, where post-sedimentary migration is limited. Approbation of the proposed measurement technique is discussed. Conclusion. The prevailing winds in the side arms of mountain gorges can differ significantly from the wind rose observed in the main part of the gorge and are determined mainly by landscape features near the observation point. This must be taken into account when measuring and analyzing the direction of migration of chemicals in mountain gorges. Mathematical modeling of aerodynamic processes in mountainous regions is a proven method for studying physical processes in mountain gorges, as well as the processes of dispersion of volatile geochemical elements emitted by sources in mountain gorges. It is shown that at the nearby points of the mountain gorge, the wind roses can differ significantly, which is confirmed by both measurements and mathematical modeling. This dictates the need for observations and taking into account the local wind rose at each measurement point. The results of radon measurements are presented, confirming the effectiveness of the proposed technique. Resume. 1. The article presents the results of mathematical modeling of aerodynamic processes in mountain gorges and the spread of gaseous impurities in the air. 2. It has been established that wind roses at nearby points on the slopes of a mountain gorge can differ significantly, both in the results of the mathematical model and in the results of measurements from weather stations. It is shown that the agreement between the modeling and measurement results is satisfactory. 3. The research results can be useful in planning measurements of radon concentrations as a predictive map of the distribution of mountain radon concentrations.

Synthesis of Poly(δ-caprolactone) via Bis(phenolate) Rare-Earth Metal Complexes Mediated Ring-Opening Polymerization and Its Chemical Recycling.

New amine-amino-bis(phenolate) ligands (H2LtBu and H2LCl) with a cyclic tertiary amine (pyrrolidine) as a side arm and tBu or Cl group on the phenolate ring have been prepared. The alkane elimination reaction between these free ligands and rare-earth tris(alkyl)s Ln(CH2SiMe3)3(THF)2 afforded the corresponding silylalkyl complexes LtBuLnCH2SiMe3(THF) (Ln = Y (1), Lu (2)) and LClYCH2SiMe3(THF) (3), where the solid-state structure of complex 1 was unambiguously confirmed by X-ray diffraction (XRD) analysis. These rare-earth metal complexes have been utilized as catalysts for the ring-opening polymerization (ROP) of biobased δ-caprolactone (δCL), either in the absence or presence of alcohols, to give poly(δ-caprolactone) (PδCL) with controlled molecular weight and narrow distribution (Đ < 1.2). The polymerization kinetics of δCL in toluene with yttrium complexes 1 and 3 were investigated. Oligomers prepared with complex 3 alone and the 3/PhCHMeOH binary catalyst system were well characterized with 1H NMR spectroscopy and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF MS). Moreover, chemical recycling of the resultant PδCL was achieved with high yield in a solution at ambient temperature (>92%) or in bulk at 130 °C (>82%) by using commercial KOtBu as a promotor.

Adding an extension piece to the end of the purge side arm of the Impella device can prevent the incidence of the cassette breaking and decrease the Impella device failure rate: Impact of practice change on patient outcome.

Background: Impella 5.5® with Smart Assist is a minimally invasive Left Ventricular Assist Devices (LVAD) approved by the Food and Drug Administration (FDA) for treating ongoing cardiogenic shock for up to 14 days. The Impella® intends to reduce ventricular workload and provide the circulatory support necessary for myocardial recovery.Research Question: Compared to standard practice, does adding an extension piece to the purge tube side arm of the Impella® Device decrease the incidence of device failure and positively impact the health outcome of adult patients receiving Impella® support?Study Design and Methods: A retrospective chart review of ICU patients was done at a tertiary care center from August 2018 to August 2022 to assess the differences in patient outcomes related to Impella® Device utilization before and after the implementation of the extension piece to the purge tube sidearm. Among patients reviewed, a total of 20 were included in our review, with seven not having the purge tube side arm extension added, while 13 patients had the extension.Results: The two study groups had no significant difference in patient health outcomes. Additionally, there were no instances of device failure requiring explanation without the extension tubing. However, there were no cases of the purge cassette cracking with the addition of the extension tubing.Conclusion: The addition of extension tubing to the purge cassette of the Impella® Device did not impact patient health outcomes or the incidence of device failure. There was a complete reduction in the incidence of the purge cassette cracking, which could reduce the potential for infection or device failure over a long period of mechanical support. There is a need for long-term prospective studies to confirm the results.

The effects of health education and exercise style changes on the maturation of autologous arteriovenous fistula in hemodialysis patients: A randomized controlled trial.

Upper limb exercise has long been considered to be the main means to promote autogenous arteriovenous fistula (AVF) maturation, but in practice exercise intensity and compliance are both typically lacking. Several randomized controlled trials (RCTs) have demonstrated the good effects of functional resistance or pressure exercise in patients with AVF. However, many patients' have difficulty complying with upper limb exercise programs without systematic health education. Therefore, we argue that resistance and pressure exercise supported by health education is actually the most beneficial for AVF patients. We randomly divided 114 patients into a control group and an experimental group of 57 patients each. In the control group, conventional care was used, and in the experimental group, online health education based on the IMB (Information-Motivation-Behavior skills) model and functional resistance and pressure upper limb exercises was implemented with the AVF side arm. The failure rate of AVF maturation, clinical maturation time, cephalic venous blood flow, vessel diameter, and vessel skin thickness were compared between the two groups. Fifty-five cases were included for each in the final study. The primary outcome of this study was the failure rate of AVF maturation. Secondary outcomes included clinical maturation time, cephalic vein flow, vessel diameter, and vessel thickness. The failure rate of AVF maturation in the experimental group was significantly lower than that in the control group, and the clinical maturation time in the experimental group was significantly shorter than that in the control group. For the remaining three indicators, there were between-group effects, time effects, and interaction effects in both groups. Comparison between groups showed that there was no statistical difference in the observed indicators of cephalic vein flow, vessel diameter, or vessel thickness between the two groups before the intervention but that there was a statistical difference at the end of the 4th, 8th, and 12th weeks of the intervention. A 2 × 2 comparison also showed that there was a statistical difference between the three indicators at each time point within the two groups. IMB model-based online health education combined with functional resistance and pressure exercises can improve AVF maturation status and accelerate AVF maturation within 12 weeks of surgery.

Mechanistic study on the side arm effect in a palladium/Xu-Phos-catalyzed enantioselective alkoxyalkenylation of γ-hydroxyalkenes

Recently, the asymmetric bifunctionalization of alkenes has received much attention. However, the development of enantioselective alkoxyalkenylation has posed a considerable challenge and has lagged largely behind. Herein, we report a new palladium-catalyzed enantioselective alkoxyalkenylation reaction, using a range of primary, secondary, and tertiary γ-hydroxy-alkenes with alkenyl halides. By employing newly identified Xu-Phos (Xu8 and Xu9) with a suitable side-arm adjacent to the PCy2 motif, a series of allyl-substituted tetrahydrofurans were obtained in good yields with up to 95% ee. Besides (E)-alkenyl halides, (Z)-alkenyl halide was also examined and provided the corresponding (Z)-product as a single diastereomer, supporting a stereospecific oxidative addition and reductive elimination step. Moreover, deuterium labeling and VCD experiments were employed to determine a cis-oxypalladation mechanism. DFT calculations helped us gain deeper insight into the side-arm effect on the chiral ligand. Finally, the practicability of this method is further demonstrated through a gram-scale synthesis and versatile transformations of the products.

Geometrically Compelled Silicon(II)/Silicon(IV) Donor-Acceptor Interaction Enables the Enamination of Nitriles.

Discovering new bonding scenarios and subsequently exploring the reactivity contribute substantially to advance the main group element chemistry. Herein, we report on the isolation and characterization of an intriguing class of the hydrido-benzosiloles 2-4. These compounds exhibit a side arm of the amidinatosilylenyl group, featuring unidirectional silicon(II)/silicon(IV) donor-acceptor interaction on account of the geometric constraint. Furthermore, the reactions involving 2-4 with nitriles yield the tricyclic compounds that edge-fused of the Si-heteroimidazolidine-CN2 Si2 , silole-C4 Si, and phenyl-C6 -rings (5-13). These compounds are manifesting a unique reaction that the silicon(II)/silicon(IV) interaction enables the enamination of the α-H-bearing nitriles. The reaction mechanism involved in H-shift under oxidative addition at silylene followed by hydrosilylation of a ketenimine intermediate was revealed by density function theory (DFT) calculations.