Reversible non-volatile electronic switching in a near-room-temperature van der Waals ferromagnet.

Non-volatile phase-change memory devices utilize local heating to toggle between crystalline and amorphous states with distinct electrical properties. Expanding on this kind of switching to two topologically distinct phases requires controlled non-volatile switching between two crystalline phases with distinct symmetries. Here, we report the observation of reversible and non-volatile switching between two stable and closely related crystal structures, with remarkably distinct electronic structures, in the near-room-temperature van der Waals ferromagnet Fe5-δGeTe2. We show that the switching is enabled by the ordering and disordering of Fe site vacancies that results in distinct crystalline symmetries of the two phases, which can be controlled by a thermal annealing and quenching method. The two phases are distinguished by the presence of topological nodal lines due to the preserved global inversion symmetry in the site-disordered phase, flat bands resulting from quantum destructive interference on a bipartite lattice, and broken inversion symmetry in the site-ordered phase.

Tethering Three Radical Cascades for Controlled Termination of Radical Alkyne peri-Annulations: Making Phenalenyl Ketones without Oxidants.

Although Bu3Sn-mediated radical alkyne peri-annulations allow access to phenalenyl ring systems, the oxidative termination of these cascades provides only a limited selection of the possible isomeric phenalenone products with product selectivity controlled by the intrinsic properties of the new cyclic systems. In this work, we report an oxidant-free termination strategy that can overcome this limitation and enable selective access to the full set of isomerically functionalized phenalenones. The key to preferential termination is the preinstallation of a "weak link" that undergoes C-O fragmentation in the final cascade step. Breaking a C-O bond is assisted by entropy, gain of conjugation in the product, and release of stabilized radical fragments. This strategy is expanded to radical exo-dig cyclization cascades of oligoalkynes, which provide access to isomeric π-extended phenalenones. Conveniently, these cascades introduce functionalities (i.e., Bu3Sn and iodide moieties) amenable to further cross-coupling reactions. Consequently, a variety of polyaromatic diones, which could serve as phenalenyl-based open-shell precursors, can be synthesized.

Excessive daytime sleepiness is associated with increased residual cardiovascular risks among coronary artery disease patients with obstructive sleep apnea.

OBJECTIVE: Excessive daytime sleepiness (EDS) frequently accompanies obstructive sleep apnea (OSA) and may increase cardiovascular risks. The majority of coronary artery disease (CAD) patients receive understandard treatments, it is not clear whether EDS is associated with increased residual cardiovascular risks in CAD patients with OSA. METHOD: This study is a prospective cohort study that included 1215 consecutive CAD patients underwent overnight sleep study with a 3.7 year follow-up. Sleepiness was is determined by the Epworth Sleepiness Scale questionnaire. The primary endpoint was major adverse cardiovascular and cerebrovascular events (MACCE), including cardiovascular death, myocardial infarction, stroke, and heart failure. Kaplan-Meier model and Cox proportional hazards models were used to explore the relationship between residual cardiovascular risks and EDS. RESULT: 1027 cases were eventually enrolled, and a total of 129 patients experienced cardiovascular and cerebrovascular events. Participants with EDS had a higher risk of MACCE compared to those without EDS (17.02% vs. 9.58%, P = 0.005). The presence of EDS is associated with higher incidence of MACCE compared to non-EDS patients (HR 2.833; 95%CI:1.394-5.762; P < 0.001). EDS was significantly associated with increased incidence of MACCE in OSA patients (HR 1.765; 95%CI:1.276-2.543; P = 0.193), while there was no significant association between EDS and cardiovascular risks in non-OSA patients (HR 1.233; 95%CI: 0.893-2.755; P = 0.127). CONCLUSIONS: The existence of EDS may lead to increased cardiovascular risks, EDS is associated with increased cardiovascular risks in CAD patients, especially in patients with OSA.

Recent progress in MnBi2nTe3n+1 intrinsic magnetic topological insulators: crystal growth, magnetism and chemical disorder.

The search for magnetic topological materials has been at the forefront of condensed matter research for their potential to host exotic states such as axion insulators, magnetic Weyl semimetals, Chern insulators, etc. To date, the MnBi2nTe3n+1 family is the only group of materials showcasing van der Waals-layered structures, intrinsic magnetism and non-trivial band topology without trivial bands at the Fermi level. The interplay between magnetism and band topology in this family has led to the proposal of various topological phenomena, including the quantum anomalous Hall effect, quantum spin Hall effect and quantum magnetoelectric effect. Among these, the quantum anomalous Hall effect has been experimentally observed at record-high temperatures, highlighting the unprecedented potential of this family of materials in fundamental science and technological innovation. In this paper, we provide a comprehensive review of the research progress in this intrinsic magnetic topological insulator family, with a focus on single-crystal growth, characterization of chemical disorder, manipulation of magnetism through chemical substitution and external pressure, and important questions that remain to be conclusively answered.

Observation of fractionally quantized anomalous Hall effect.

The integer quantum anomalous Hall (QAH) effect is a lattice analogue of the quantum Hall effect at zero magnetic field1-3. This phenomenon occurs in systems with topologically non-trivial bands and spontaneous time-reversal symmetry breaking. Discovery of its fractional counterpart in the presence of strong electron correlations, that is, the fractional QAH effect4-7, would open a new chapter in condensed matter physics. Here we report the direct observation of both integer and fractional QAH effects in electrical measurements on twisted bilayer MoTe2. At zero magnetic field, near filling factor ν = -1 (one hole per moiré unit cell), we see an integer QAH plateau in the Hall resistance Rxy quantized to h/e2 ± 0.1%, whereas the longitudinal resistance Rxx vanishes. Remarkably, at ν = -2/3 and -3/5, we see plateau features in Rxy at [Formula: see text] and [Formula: see text], respectively, whereas Rxx remains small. All features shift linearly versus applied magnetic field with slopes matching the corresponding Chern numbers -1, -2/3 and -3/5, precisely as expected for integer and fractional QAH states. Additionally, at zero magnetic field, Rxy is approximately 2h/e2 near half-filling (ν = -1/2) and varies linearly as ν is tuned. This behaviour resembles that of the composite Fermi liquid in the half-filled lowest Landau level of a two-dimensional electron gas at high magnetic field8-14. Direct observation of the fractional QAH and associated effects enables research in charge fractionalization and anyonic statistics at zero magnetic field.

Metabolic systems approaches update molecular insights of clinical phenotypes and cardiovascular risk in patients with homozygous familial hypercholesterolemia.

BACKGROUND: Homozygous familial hypercholesterolemia (HoFH) is an orphan metabolic disease characterized by extremely elevated low-density lipoprotein cholesterol (LDL-C), xanthomas, aortic stenosis, and premature atherosclerotic cardiovascular disease (ASCVD). In addition to LDL-C, studies in experimental models and small clinical populations have suggested that other types of metabolic molecules might also be risk factors responsible for cardiovascular complications in HoFH, but definitive evidence from large-scale human studies is still lacking. Herein, we aimed to comprehensively characterize the metabolic features and risk factors of human HoFH by using metabolic systems strategies. METHODS: Two independent multi-center cohorts with a total of 868 individuals were included in the cross-sectional study. First, comprehensive serum metabolome/lipidome-wide analyses were employed to identify the metabolomic patterns for differentiating HoFH patients (n = 184) from heterozygous FH (HeFH, n = 376) and non-FH (n = 100) subjects in the discovery cohort. Then, the metabolomic patterns were verified in the validation cohort with 48 HoFH patients, 110 HeFH patients, and 50 non-FH individuals. Subsequently, correlation/regression analyses were performed to investigate the associations of clinical/metabolic alterations with typical phenotypes of HoFH. In the prospective study, a total of 84 HoFH patients with available follow-up were enrolled from the discovery cohort. Targeted metabolomics, deep proteomics, and random forest approaches were performed to investigate the ASCVD-associated biomarkers in HoFH patients. RESULTS: Beyond LDL-C, various bioactive metabolites in multiple pathways were discovered and validated for differentiating HoFH from HoFH and non-FH. Our results demonstrated that the inflammation and oxidative stress-related metabolites in the pathways of arachidonic acid and lipoprotein(a) metabolism were independently associated with the prevalence of corneal arcus, xanthomas, and supravalvular/valvular aortic stenosis in HoFH patients. Our results also identified a small marker panel consisting of high-density lipoprotein cholesterol, lipoprotein(a), apolipoprotein A1, and eight proinflammatory and proatherogenic metabolites in the pathways of arachidonic acid, phospholipid, carnitine, and sphingolipid metabolism that exhibited significant performances on predicting first ASCVD events in HoFH patients. CONCLUSIONS: Our findings demonstrate that human HoFH is associated with a variety of metabolic abnormalities and is more complex than previously known. Furthermore, this study provides additional metabolic alterations that hold promise as residual risk factors in HoFH population.

Vascular smooth muscle cells specific deletion of angiopoietin-like protein 8 prevents angiotensin II-promoted hypertension and cardiovascular hypertrophy.

AIMS: Angiopoietin-like protein 8 (ANGPTL8) plays important roles in lipid metabolism, glucose metabolism, inflammation, and cell proliferation and migration. Clinical studies have indicated that circulating ANGPTL8 concentrations are increased in patients with hypertension and positively associated with blood pressure. ANGPTL8 deficiency ameliorates blood pressure in mice treated with chronic intermittent hypoxia. Currently, little is known regarding the pathophysiological role of the vascular smooth muscle cell (VSMC)-derived ANGPTL8 in hypertension and hypertensive cardiovascular remodelling. METHODS AND RESULTS: Circulating ANGPTL8 concentrations, as determined by enzyme-linked immunosorbent assay, were significantly higher in hypertensive patients than in controls (524.51 ± 26.97 vs. 962.92 ± 15.91 pg/mL; P < 0.001). In hypertensive mice [angiotensin II (AngII) treatment for 14 days] and spontaneously hypertensive rats, ANGPTL8 expression was increased and predominantly located in VSMCs. In AngII-treated mice, systolic and diastolic blood pressure in Tagln-Cre-ANGPTL8fl/fl mice were approximately 15-25 mmHg lower than that in ANGPTL8fl/fl mice. AngII-induced vascular remodelling, vascular constriction, and increased expression of cell markers of proliferation (PCNA and Ki67) and migration (MMP-2 and MMP-9) were strikingly attenuated in Tagln-Cre-ANGPTL8fl/fl mice compared with ANGPTL8fl/fl mice. Furthermore, the AngII-induced increase in the heart size, heart weight, heart/body weight ratio, cardiomyocyte cross-sectional area, and collagen deposition was ameliorated in Tagln-Cre-ANGPTL8fl/fl mice compared with ANGPTL8fl/fl mice. In rat artery smooth muscle cells, ANGPTL8-short hairpin RNA decreased intracellular calcium levels and prevented AngII-induced proliferation and migration through the PI3K-Akt pathway, as shown using LY294002 (inhibitor of PI3K) and Akt inhibitor VIII. CONCLUSION: This study suggests that ANGPTL8 in VSMCs plays an important role in AngII-induced hypertension and associated cardiovascular remodelling. ANGPTL8 may be a novel therapeutic target against pathological hypertension and hypertensive cardiovascular hypertrophy.

Quantum metric nonlinear Hall effect in a topological antiferromagnetic heterostructure.

Quantum geometry in condensed-matter physics has two components: the real part quantum metric and the imaginary part Berry curvature. Whereas the effects of Berry curvature have been observed through phenomena such as the quantum Hall effect in two-dimensional electron gases and the anomalous Hall effect (AHE) in ferromagnets, the quantum metric has rarely been explored. Here, we report a nonlinear Hall effect induced by the quantum metric dipole by interfacing even-layered MnBi2Te4 with black phosphorus. The quantum metric nonlinear Hall effect switches direction upon reversing the antiferromagnetic (AFM) spins and exhibits distinct scaling that is independent of the scattering time. Our results open the door to discovering quantum metric responses predicted theoretically and pave the way for applications that bridge nonlinear electronics with AFM spintronics.

ANGPTL8 deletion attenuates abdominal aortic aneurysm formation in ApoE-/- mice.

Angiopoietin-like protein 8 (ANGPTL8) plays important roles in lipid metabolism, glucose metabolism, inflammation, and cell proliferation and migration. Clinical studies have indicated that circulating ANGPTL8 levels are increased in patients with thoracic aortic dissection (TAD). TAD shares several risk factors with abdominal aortic aneurysm (AAA). However, the role of ANGPTL8 in AAA pathogenesis has never been investigated. Here, we investigated the effect of ANGPTL8 knockout on AAA in ApoE-/- mice. ApoE-/-ANGPTL8-/- mice were generated by crossing ANGPTL8-/- and ApoE-/- mice. AAA was induced in ApoE-/- using perfusion of angiotensin II (AngII). ANGPTL8 was significantly up-regulated in AAA tissues of human and experimental mice. Knockout of ANGPTL8 significantly reduced AngII-induced AAA formation, elastin breaks, aortic inflammatory cytokines, matrix metalloproteinase expression, and smooth muscle cell apoptosis in ApoE-/- mice. Similarly, ANGPTL8 sh-RNA significantly reduced AngII-induced AAA formation in ApoE-/- mice. ANGPTL8 deficiency inhibited AAA formation, and ANGPTL8 may therefore be a potential therapeutic target for AAA.

Design principles of the use of alkynes in radical cascades.

One of the simplest organic functional groups, the alkyne, offers a broad canvas for the design of cascade transformations in which up to three new bonds can be added to each of the two sterically unencumbered, energy-rich carbon atoms. However, kinetic protection provided by strong π-orbital overlap makes the design of new alkyne transformations a stereoelectronic puzzle, especially on multifunctional substrates. This Review describes the electronic properties contributing to the unique utility of alkynes in radical cascades. We describe how to control the selectivity of alkyne activation by various methods, from dynamic covalent chemistry with kinetic self-sorting to disappearing directing groups. Additionally, we demonstrate how the selection of reactive intermediates directly influences the propagation and termination of the cascade. Diverging from a common departure point, a carefully planned reaction route can allow access to a variety of products.

Axion optical induction of antiferromagnetic order.

Using circularly polarized light to control quantum matter is a highly intriguing topic in physics, chemistry and biology. Previous studies have demonstrated helicity-dependent optical control of chirality and magnetization, with important implications in asymmetric synthesis in chemistry; homochirality in biomolecules; and ferromagnetic spintronics. We report the surprising observation of helicity-dependent optical control of fully compensated antiferromagnetic order in two-dimensional even-layered MnBi2Te4, a topological axion insulator with neither chirality nor magnetization. To understand this control, we study an antiferromagnetic circular dichroism, which appears only in reflection but is absent in transmission. We show that the optical control and circular dichroism both arise from the optical axion electrodynamics. Our axion induction provides the possibility to optically control a family of [Formula: see text]-symmetric antiferromagnets ([Formula: see text], inversion; [Formula: see text], time-reversal) such as Cr2O3, even-layered CrI3 and possibly the pseudo-gap state in cuprates. In MnBi2Te4, this further opens the door for optical writing of a dissipationless circuit formed by topological edge states.

Metabolomic Approach to Screening Homozygotes in Chinese Patients with Severe Familial Hypercholesterolemia.

Homozygous familial hypercholesterolemia (HoFH) is a rare inborn-errors-of-metabolism disorder characterized by devastatingly elevated low-density lipoprotein cholesterol (LDL-C) and premature cardiovascular disease. The gold standard for screening and diagnosing HoFH is genetic testing. In China, it is expensive and is always recommended for the most likely HoFH subjects with aggressive LDL-C phenotype. However, the LDL-C levels of HoFH patients and a substantial proportion of heterozygous FH (HeFH) patients overlapped considerably. Here, we performed a cost-effective metabolomic profiling on genetically diagnosed HoFH (n = 69) and HeFH patients (n = 101) with overlapping LDL-C levels, aiming to discovery a unique metabolic pattern for screening homozygotes in patients with severe FH. We demonstrated a differential serum metabolome profile in HoFH patients compared to HeFH patients. Twenty-one metabolomic alterations showed independent capability in differentiating HoFH from severe HeFH. The combined model based on seven identified metabolites yielded a corrected diagnosis in 91.3% of HoFH cases with an area under the curve value of 0.939. Collectively, this study demonstrated that metabolomic profiling serves as a useful and economical approach to preselecting homozygotes in FH patients with severe hypercholesterolemia and may help clinicians to conduct selective genetic confirmation testing and familial cascade screening.

Design and Synthesis of Kekulè and Non-Kekulè Diradicaloids via the Radical Periannulation Strategy: The Power of Seven Clar's Sextets.

This work introduces an approach to uncoupling electrons via maximum utilization of localized aromatic units, i.e., the Clar's π-sextets. To illustrate the utility of this concept to the design of Kekulé diradicaloids, we have synthesized a tridecacyclic polyaromatic system where a gain of five Clar's sextets in the open-shell form overcomes electron pairing and leads to the emergence of a high degree of diradical character. According to unrestricted symmetry-broken UCAM-B3LYP calculations, the singlet diradical character in this core system is characterized by the y0 value of 0.98 (y0 = 0 for a closed-shell molecule, y0 = 1 for pure diradical). The efficiency of the new design strategy was evaluated by comparing the Kekulé system with an isomeric non-Kekulé diradical of identical size, i.e., a system where the radical centers cannot couple via resonance. The calculated singlet-triplet gap, i.e., the ΔEST values, in both of these systems approaches zero: -0.3 kcal/mol for the Kekulé and +0.2 kcal/mol for the non-Kekulé diradicaloids. The target isomeric Kekulé and non-Kekulé systems were assembled using a sequence of radical periannulations, cross-coupling, and C-H activation. The diradicals are kinetically stabilized by six tert-butyl substituents and (triisopropylsilyl)acetylene groups. Both molecules are NMR-inactive but electron paramagnetic resonance (EPR)-active at room temperature. Cyclic voltammetry revealed quasi-reversible oxidation and reduction processes, consistent with the presence of two nearly degenerate partially occupied molecular orbitals. The experimentally measured ΔEST value of -0.14 kcal/mol confirms that K is, indeed, a nearly perfect singlet diradical.

Comprehensive Metabolomics and Machine Learning Identify Profound Oxidative Stress and Inflammation Signatures in Hypertensive Patients with Obstructive Sleep Apnea.

Obstructive sleep apnea (OSA) can aggravate blood pressure and increase the risk of cardiovascular diseases in hypertensive individuals, yet the underlying pathophysiological process is still incompletely understood. More importantly, OSA remains a significantly undiagnosed condition. In this study, a total of 559 hypertensive patients with and without OSA were included. Metabolome and lipidome-wide analyses were performed to explore the pathophysiological processes of hypertension comorbid OSA and derive potential biomarkers for diagnosing OSA in hypertensive subjects. Compared to non-OSA hypertensive patients (discovery set = 120; validation set = 116), patients with OSA (discovery set = 165; validation set = 158) demonstrated a unique sera metabolic phenotype dominated by abnormalities in biological processes of oxidative stress and inflammation. By integrating three machine learning algorithms, six discriminatory metabolites (including 5-hydroxyeicosatetraenoic acid, taurine, histidine, lysophosphatidic acid 16:0, lysophosphatidylcholine 18:0, and dihydrosphingosine) were selected for constructing diagnostic and classified model. Notably, the established multivariate-model could accurately identify OSA subjects. The corresponding area under the curve values and the correct classification rates were 0.995 and 96.8% for discovery sets, 0.997 and 99.1% for validation sets. This work updates the molecular insights of hypertension comorbid OSA and paves the way for the use of metabolomics for the diagnosis of OSA in hypertensive individuals.

ANGPTL3 and Cardiovascular Outcomes in Patients With Acute Coronary Syndrome and Obstructive Sleep Apnea.

Background The aim of this prospective study was to determine the impact of elevated ANGPTL3 (angiopoietin-like protein 3) on cardiovascular events (CVEs) following acute coronary syndrome (ACS) in patients with or without obstructive sleep apnea (OSA). Methods and Results A total of 1174 patients with ACS underwent successful percutaneous coronary intervention were included in this prospective cohort study (NCT03362385). Patients were categorized according to the apnea-hypopnea index (≥15 events/h, OSA) and further classified by ANGPTL3 levels. We analyzed the incidence of CVEs in patients with ACS according to the status of OSA and ANGPTL3. During a median of 3.1 years of follow-up, 217 (18.48%) CVEs occurred. The patients with ACS with OSA had higher ANGPTL3 levels than those without OSA (30.4 [20.9-43.2] versus 27.80 [19.1-41.5] ng/mL; P<0.001). In all patients with ACS, 29≤ANGPTL3<42 mg/dL and ANGPTL3≥42 mg/dL were associated with an increased risk of CVEs with hazard ratios (HRs) of 1.555 (95% CI, 1.010-2.498) and 2.489 (95% CI 1.613-3.840), respectively. When the status of OSA or not was incorporated in stratifying factors, 29≤ANGPTL3<42 mg/dL and ANGPTL3≥42 mg/dL were associated with a significantly higher risk of CVEs in patients with ACS with OSA (HR, 1.916 [95% CI, 1.019-3.601] and HR, 2.692 [95% CI, 1.379-4.503]) but not without OSA. Moreover, adding ANGPTL3 to the Cox model increased C-statistic values by 0.035 and 0.029 in the OSA group and all patients with ACS, respectively, but was not statistically improved in patients with ACS without OSA. Conclusions In conclusion, our study demonstrates a predictive impact of plasma ANGPTL3 on cardiovascular risk in patients with ACS, especially in patients with ACS with OSA. It might be of clinical value in refining risk stratification and tailoring treatment of patients with ACS and OSA. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03362385.

A Swiss Army knife for surface chemistry.

Voltage pulses offer a way to control single-molecule reactions on a surface.

Increasing circulating ESM-1 and adhesion molecules are associated with earlystage atherosclerosis in OSA patients:A cross-sectional study.

BACKGROUND: There are increasing evidences for a direct relationship between the vascular system and obstructive sleep apnea (OSA). The aim of this study was to investigate the relationship between circulating endothelial cell specific molecule-1 (ESM-1), adhesion molecules and subclinical atherosclerosis in patients with OSA. METHODS: This was a cross-sectional study in which 161 patients with OSA and 56 controls were recruited. Demographic data, biochemical and polysomnography parameters were collected. We used a powerful high-throughput Multiplex Immunobead Assay technique to simultaneously test plasm levels of ESM-1, P-selectin, E-selectin, L-selectin, inter-cellular adhesion molecule 1 (ICAM-1), and vascular cell adhesion molecule 1 (VCAM-1). Carotid intima-media thickness (CIMT) were measured as parameters of vascular endothelial dysfunction and early atherosclerosis. RESULTS: Increasing circulating levels of ESM-1, P-selectin, E-selectin, L-selectin, ICAM-1 and VCAM-1 were found increased in patients with OSA (all P < 0.001). Furthermore, OSA patients exhibited increased CIMT than controls (P < 0.05). Multivariate linear analysis indicated that elevated ESM-1, P-Selectin, E-selectin, and L-selectin levels were associated with AHI (all P < 0.05). Moreover, multivariate analysis showed that increasing ESM-1, VCAM-1, P-Selectin, and L-selectin were significantly associated with thick CIMT in OSA patients (all P < 0.05). CONCLUSIONS: Increased circulating ESM-1 and adhesion molecules associated with thick CIMT in OSA, which is a marker of subclinical atherosclerosis. Strict attention to monitor circulating ESM-1 and adhesion molecules is necessary for early detection of subclinical atherosclerosis in OSA patients.

Quantum Imaging of Magnetic Phase Transitions and Spin Fluctuations in Intrinsic Magnetic Topological Nanoflakes.

Topological materials featuring exotic band structures, unconventional current flow patterns, and emergent organizing principles offer attractive platforms for the development of next-generation transformative quantum electronic technologies. The family of MnBi2Te4 (Bi2Te3)n materials is naturally relevant in this context due to their nontrivial band topology, tunable magnetism, and recently discovered extraordinary quantum transport behaviors. Despite numerous pioneering studies to date, the local magnetic properties of MnBi2Te4 (Bi2Te3)n remain an open question, hindering a comprehensive understanding of their fundamental material properties. Exploiting nitrogen-vacancy (NV) centers in diamond, we report nanoscale quantum imaging of the magnetic phase transitions and spin fluctuations in exfoliated MnBi4Te7 flakes, revealing the underlying spin transport physics and magnetic domains at the nanoscale. Our results highlight the unique advantage of NV centers in exploring the magnetic properties of emergent quantum materials, opening new opportunities for investigating the interplay between topology and magnetism.

Localized Antiaromaticity Hotspot Drives Reductive Dehydrogenative Cyclizations in Bis- and Mono-Helicenes.

We describe reductive dehydrogenative cyclizations that form hepta-, nona-, and decacyclic anionic graphene subunits from mono- and bis-helicenes with an embedded five-membered ring. The reaction of bis-helicenes can either proceed to the full double annulation or be interrupted by addition of molecular oxygen at an intermediate stage. The regioselectivity of the interrupted cyclization cascade for bis-helicenes confirms that relief of antiaromaticity is a dominant force for these facile ring closures. Computational analysis reveals the unique role of the preexisting negatively charged cyclopentadienyl moiety in directing the second negative charge at a specific remote location and, thus, creating a localized antiaromatic region. This region is the hotspot that promotes the initial cyclization. Computational studies, including MO analysis, molecular electrostatic potential maps, and NICS(1.7)ZZ calculations, evaluate the interplay of the various effects including charge delocalization, helicene strain release, and antiaromaticity. The role of antiaromaticity relief is further supported by efficient reductive closure of the less strained monohelicenes where the relief of antiaromaticity promotes the cyclization even when the strain is substantially reduced. The latter finding significantly expands the scope of this reductive alternative to the Scholl ring closure.

Unconventional Pressure-Driven Metamagnetic Transitions in Topological van der Waals Magnets.

Activating metamagnetic transitions between ordered states in van der Waals magnets and devices bring great opportunities in spintronics. We show that external pressure, which enhances the interlayer hopping without introducing chemical disorders, triggers multiple metamagnetic transitions upon cooling in the topological van der Waals magnets Mn(Bi1-xSbx)4Te7, where the antiferromagnetic interlayer superexchange coupling competes with the ferromagnetic interlayer coupling mediated by the antisite Mn spins. The temperature-pressure phase diagrams reveal that while the ordering temperature from the paramagnetic to ordered states is almost pressure-independent, the metamagnetic transitions show nontrivial pressure and temperature dependence, even re-entrance. For these highly anisotropic magnets, we attribute the former to the ordering temperature being only weakly dependent on the intralayer parameters and the latter to the parametrically different pressure and temperature dependence of the two interlayer couplings. Our independent probing of these disparate magnetic interactions paves an avenue for efficient magnetic manipulations in van der Waals magnets.