Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 412
Filtrar
Más filtros

País/Región como asunto
Tipo del documento
Intervalo de año de publicación
1.
Nature ; 594(7862): 283-288, 2021 06.
Artículo en Inglés | MEDLINE | ID: mdl-33981036

RESUMEN

Homologous recombination (HR) repairs DNA double-strand breaks (DSBs) in the S and G2 phases of the cell cycle1-3. Several HR proteins are preferentially recruited to DSBs at transcriptionally active loci4-10, but how transcription promotes HR is poorly understood. Here we develop an assay to assess the effect of local transcription on HR. Using this assay, we find that transcription stimulates HR to a substantial extent. Tethering RNA transcripts to the vicinity of DSBs recapitulates the effects of local transcription, which suggests that transcription enhances HR through RNA transcripts. Tethered RNA transcripts stimulate HR in a sequence- and orientation-dependent manner, indicating that they function by forming DNA-RNA hybrids. In contrast to most HR proteins, RAD51-associated protein 1 (RAD51AP1) only promotes HR when local transcription is active. RAD51AP1 drives the formation of R-loops in vitro and is required for tethered RNAs to stimulate HR in cells. Notably, RAD51AP1 is necessary for the DSB-induced formation of DNA-RNA hybrids in donor DNA, linking R-loops to D-loops. In vitro, RAD51AP1-generated R-loops enhance the RAD51-mediated formation of D-loops locally and give rise to intermediates that we term 'DR-loops', which contain both DNA-DNA and DNA-RNA hybrids and favour RAD51 function. Thus, at DSBs in transcribed regions, RAD51AP1 promotes the invasion of RNA transcripts into donor DNA, and stimulates HR through the formation of DR-loops.


Asunto(s)
ADN/genética , ADN/metabolismo , Recombinación Homóloga/genética , Estructuras R-Loop/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Transcripción Genética , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Línea Celular , ADN/química , Roturas del ADN de Doble Cadena , Reparación del ADN , Proteínas de Unión al ADN/metabolismo , Genes/genética , Genes Reporteros/genética , Proteínas Fluorescentes Verdes/genética , Humanos , Técnicas In Vitro , ARN Mensajero/química , Proteínas de Unión al ARN/metabolismo , Recombinasa Rad51/metabolismo
2.
Proc Natl Acad Sci U S A ; 119(12): e2116251119, 2022 03 22.
Artículo en Inglés | MEDLINE | ID: mdl-35290126

RESUMEN

RNA modifications regulate a variety of cellular processes including DNA repair.The RNA methyltransferase TRDMT1 generates methyl-5-cytosine (m5C) on messen-ger RNA (mRNA) at DNA double-strand breaks (DSBs) in transcribed regions, pro-moting transcription-coupled homologous recombination (HR). Here, we identifiedthat Fragile X mental retardation protein (FMRP) promotes transcription-coupled HRvia its interaction with both the m5C writer TRDMT1 and the m5C eraser ten-eleventranslocation protein 1 (TET1). TRDMT1, FMRP, and TET1 function in a temporalorder at the transcriptionally active sites of DSBs. FMRP displays a higher affinity forDNA:RNA hybrids containing m5C-modified RNA than for hybrids without modifica-tion and facilitates demethylation of m5C by TET1 in vitro. Loss of either the chroma-tin- or RNA-binding domain of FMRP compromises demethylation of damage-inducedm5C in cells. Importantly, FMRP is required for R-loop resolving in cells. Due to unre-solved R-loop and m5C preventing completion of DSB repair, FMRP depletion or lowexpression leads to delayed repair of DSBs at transcriptionally active sites and sensitizescancer cells to radiation in a BRCA-independent manner. Together, ourfindings presentan m5C reader, FMRP, which acts as a coordinator between the m5C writer and eraserto promote mRNA-dependent repair and cell survival in cancer.


Asunto(s)
Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil , Síndrome del Cromosoma X Frágil , Citosina , Desmetilación , Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil/genética , Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil/metabolismo , Síndrome del Cromosoma X Frágil/genética , Recombinación Homóloga , Humanos , Oxigenasas de Función Mixta/metabolismo , Proteínas Proto-Oncogénicas/metabolismo , ARN/genética , ARN/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo
3.
Chem Soc Rev ; 53(12): 6042-6067, 2024 Jun 17.
Artículo en Inglés | MEDLINE | ID: mdl-38770558

RESUMEN

A steady stream of material transport based on carriers and channels in living systems plays an extremely important role in normal life activities. Inspired by nature, researchers have extensively applied supramolecular cages in cargo transport because of their unique three-dimensional structures and excellent physicochemical properties. In this review, we will focus on the development of supramolecular cages as carriers and channels for cargo transport in abiotic and biological systems over the past fifteen years. In addition, we will discuss future challenges and potential applications of supramolecular cages in substance transport.

4.
J Cell Physiol ; : e31373, 2024 Jul 10.
Artículo en Inglés | MEDLINE | ID: mdl-38988064

RESUMEN

Cannabis, often recognized as the most widely used illegal psychoactive substance globally, has seen a shift in its legal status in several countries and regions for both recreational and medicinal uses. This change has brought to light new evidence linking cannabis consumption to various vascular conditions. Specifically, there is an association between cannabis use and atherosclerosis, along with conditions such as arteritis, reversible vasospasm, and incidents of aortic aneurysm or dissection. Recent research has started to reveal the mechanisms connecting cannabinoid compounds to atherosclerosis development. It is well known that the primary biological roles of cannabinoids operate through the activation of cannabinoid receptor types 1 and 2. Manipulation of the endocannabinoid system, either genetically or pharmacologically, is emerging as a promising approach to address metabolic dysfunctions related to obesity. Additionally, numerous studies have demonstrated the vasorelaxant properties and potential atheroprotective benefits of cannabinoids. In preclinical trials, cannabidiol is being explored as a treatment option for monocrotaline-induced pulmonary arterial hypertension. Although existing literature suggests a direct role of cannabinoids in the pathogenesis of atherosclerosis, the correlation between cannabinoids and other vascular diseases was only reported in some case series or observational studies, and its role and precise mechanisms remain unclear. Therefore, it is necessary to summarize and update previously published studies. This review article aims to summarize the latest clinical and experimental research findings on the relationship between cannabis use and vascular diseases. It also seeks to shed light on the potential mechanisms underlying these associations, offering a comprehensive view of current knowledge in this evolving field of study.

5.
Breast Cancer Res Treat ; 204(2): 223-235, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38097882

RESUMEN

PURPOSE: We aimed to evaluate whether neoadjuvant chemotherapy (NAC) could be a risk factor for breast cancer-related lymphedema (BCRL) associated with axillary lymph node dissection (ALND). PATIENTS AND METHODS: A total of 596 patients with cT0-4N0-3M0 breast cancer who underwent ALND and chemotherapy were retrospectively analyzed between March 2012 and March 2022. NAC was administered in 188 patients (31.5%), while up-front surgery in 408 (68.5%). Univariate and multivariable Cox regression analyses were performed to determine whether NAC was an independent risk factor for BCRL. With propensity score matching (PSM), the NAC group and up-front surgery group were matched 1:1 by age, body mass index (BMI), molecular subtypes, type of breast surgery, and the number of positive lymph nodes. Kaplan-Meier survival analyses were performed for BCRL between groups before and after PSM. Subgroup analyses were conducted to explore whether NAC differed for BCRL occurrence in people with different characteristics. RESULTS: At a median follow-up of 36.3 months, 130 patients (21.8%) experienced BCRL [NAC, 50/188 (26.60%) vs. up-front surgery, 80/408 (19.61%); P = 0.030]. Multivariable analysis identified that NAC [hazard ratio, 1.503; 95% CI (1.03, 2.19); P = 0.033] was an independent risk factor for BCRL. In addition, the hormone receptor-negative/human epidermal growth factor receptor 2-negative (HR-/HER2-) subtype, breast-conserving surgery (BCS), and increased positive lymph nodes significantly increased BCRL risk. After PSM, NAC remained a risk factor for BCRL [hazard ratio, 1.896; 95% CI (1.18, 3.04); P = 0.007]. Subgroup analyses showed that NAC had a consistent BCRL risk in most clinical subgroups. CONCLUSION: NAC receipt has a statistically significant increase in BCRL risk in patients with ALND. These patients should be closely monitored and may benefit from early BCRL intervention.


Asunto(s)
Linfedema del Cáncer de Mama , Neoplasias de la Mama , Linfedema , Humanos , Femenino , Neoplasias de la Mama/complicaciones , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/cirugía , Terapia Neoadyuvante/efectos adversos , Estudios Retrospectivos , Escisión del Ganglio Linfático/efectos adversos , Linfedema del Cáncer de Mama/epidemiología , Linfedema del Cáncer de Mama/etiología , Linfedema del Cáncer de Mama/patología , Axila/patología , Biopsia del Ganglio Linfático Centinela/efectos adversos , Ganglios Linfáticos/patología , Linfedema/epidemiología , Linfedema/etiología , Linfedema/patología
6.
BMC Psychiatry ; 24(1): 508, 2024 Jul 17.
Artículo en Inglés | MEDLINE | ID: mdl-39020338

RESUMEN

BACKGROUND: According to the cognitive behavioral model of social anxiety, attentional bias to negative emotional information causes and maintains anxiety. The goal of attentional bias modification (ABM) is to reduce anxiety by reducing attention bias to negative emotional information. METHOD: We used questionnaires and experiments to explore the improvement effect of ABM training on social anxiety in college students. In Study 1, we used dot-probe tasks to investigate the attentional bias to negative emotional information and the relationship with social anxiety severity in college students. In Study 2, college students with high social anxiety were divided into two groups: attentional bias modification training task group (ABM) and attention control condition task group (ACC). The ABM group received a continuous intervention for 10 days to observe changes in social anxiety levels and attentional bias scores in the pretest and posttest stages. RESULTS: The results showed that the correlation of attentional bias to negative emotional information and social anxiety severity was significant. Meanwhile, the high social anxiety participants responded more quickly to negative emotional information. After the intervention, social anxiety levels and attentional bias scores of the training group were significantly reduced. CONCLUSIONS: The results showed that attentional bias modification training can reduce attentional bias to negative emotional information in college students with social anxiety and effectively improve their social anxiety.


Asunto(s)
Sesgo Atencional , Emociones , Humanos , Masculino , Femenino , Adulto Joven , Ansiedad/psicología , Ansiedad/terapia , Estudiantes/psicología , Terapia Cognitivo-Conductual/métodos , Adulto , Adolescente , Encuestas y Cuestionarios , Fobia Social/psicología , Fobia Social/terapia
7.
BMC Psychiatry ; 24(1): 619, 2024 Sep 17.
Artículo en Inglés | MEDLINE | ID: mdl-39289668

RESUMEN

BACKGROUND: Anxiety and depression often co-occur, exhibiting high comorbidity, with their trends evolving over time. However, the specific pathways through which comorbid symptoms of anxiety and depression evolve and interact remain unclear. To investigate these questions, this study employed Network Analysis (NA) and Longitudinal Network Analysis (LNA) to explore the central symptoms of anxiety and depression, as well as the temporal evolution of these central symptoms. METHODS: The study focused on 606 high school students who were not in their final year in Shandong of China, with assessments conducted from March to September 2022. The bootnet package in R was used for establishing NA and LNA models, as well as for conducting accuracy analysis and node stability analysis. RESULTS: The results of the NA indicated that adolescent highly susceptible to anxiety and depression. And uncontrollable worry was a common central symptom, while irritability emerged as a central bridging symptom across all three NAs. The LNA results revealed that suicidal ideation and worthlessness were key central symptoms in the LNA. Furthermore, worthlessness played a pivotal role in the developmental pathway of "suicidal ideation → worthlessness → anxiety and uncontrollable worry." A reduction in suicidal ideation was associated with decreased severity in other symptoms. CONCLUSIONS: The findings suggest that adolescent anxiety and depression are in a state of vulnerability, and that irritability, worthlessness, and suicidal ideation are potential targets for interventions to address adolescent anxiety and depression.


Asunto(s)
Ansiedad , Depresión , Humanos , Adolescente , Masculino , Femenino , Depresión/psicología , Ansiedad/psicología , China/epidemiología , Estudios Longitudinales , Ideación Suicida , Comorbilidad
8.
BMC Med Imaging ; 24(1): 84, 2024 Apr 09.
Artículo en Inglés | MEDLINE | ID: mdl-38594629

RESUMEN

OBJECTIVES: Differentiating chronic total occlusion (CTO) from subtotal occlusion (SO) is often difficult to make from coronary computed tomography angiography (CCTA). We developed a CCTA-based radiomics model to differentiate CTO and SO. METHODS: A total of 66 patients with SO underwent CCTA before invasive angiography and were matched to 66 patients with CTO. Comprehensive imaging analysis was conducted for all lesioned vessels, involving the automatic identification of the lumen within the occluded segment and extraction of 1,904 radiomics features. Radiomics models were then constructed to assess the discriminative value of these features in distinguishing CTO from SO. External validation of the model was performed using data from another medical center. RESULTS: Compared to SO patients, CTO patients had more blunt stumps (internal: 53/66 (80.3%) vs. 39/66 (59.1%); external: 36/50 (72.0%) vs. 20/50 (40.0%), both p < 0.01), longer lesion length (internal: median length 15.4 mm[IQR: 10.4-22.3 mm] vs. 8.7 mm[IQR: 4.9-12.6 mm]; external:11.8 mm[IQR: 6.1-23.4 mm] vs. 6.2 mm[IQR: 3.5-9.1 mm]; both p < 0.001). Sixteen unique radiomics features were identified after the least absolute shrinkage and selection operator regression. When added to the combined model including imaging features, radiomics features provided increased value for distinguishing CTO from SO (AUC, internal: 0.772 vs. 0.846; p = 0.023; external: 0.718 vs. 0.781, p = 0.146). CONCLUSIONS: The occluded segment vessels of CTO and SO have different radiomics signatures. The combined application of radiomics features and imaging features based on CCTA extraction can enhance diagnostic confidence.


Asunto(s)
Oclusión Coronaria , Intervención Coronaria Percutánea , Humanos , Angiografía por Tomografía Computarizada/métodos , Oclusión Coronaria/diagnóstico por imagen , Oclusión Coronaria/patología , Radiómica , Angiografía Coronaria/métodos , Estudios Retrospectivos , Valor Predictivo de las Pruebas , Enfermedad Crónica
9.
Cogn Emot ; : 1-11, 2024 Jul 24.
Artículo en Inglés | MEDLINE | ID: mdl-39046729

RESUMEN

Even though some recent research revealed individuals with HSA typically display enhanced processing in the early stages of emotional information processing due to hypervigilance and vulnerability to negative stimuli, it is still unclear whether social anxiety affects the time course underlying processing bias for emotional stimuli. Therefore, the present study aimed to explore the early stage of processing social threat stimuli in high social anxiety (HSA) individuals by recording RTs and EEG data in the emotional Stroop task. Behavioral data showed that the HSA group responded to the threat words faster than neutral words (i.e. negative bias), but no emotional effects in the low social anxiety (LSA) group. Although the P1 component did not show any early effects, ERP data exhibited an enhanced N170 for HSA than for LSA groups. Threat words elicited larger N170 than neutral words in the LSA group only; this emotion effect was not evident in the HSA group. These findings indicated that social anxiety modulates early processing for social threat words. This study revealed the neural mechanisms underlying early emotional processing in individuals with social anxiety, providing insights for the evaluation and intervention of social anxiety.

10.
Environ Toxicol ; 39(5): 2502-2511, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38180308

RESUMEN

The purpose of this study was to explore the effects of combined lead (Pb) and two types of microplastic (MP) (polyvinyl chloride [PVC] and polyethylene [PE]) exposure on glucose metabolism and investigate the role of the nuclear factor erythroid 2-related factor 2 (Nrf2)/nuclear factor-kappa B (NF-κB) signaling pathway in mediating these effects in mice. Adult C57BL/6J mice were randomly divided into four groups: control, Pb (100 mg/L), MPs (containing 10 mg/L PE and PVC), and Pb + MPs, each of which was treated with drinking water. Treatments were conducted for 6 weeks. Co-exposure to Pb + MPs exhibited increase glycosylated serum protein levels, insulin resistance, and damaged glucose tolerance compared with the control mice. Additionally, treatment with Pb + MPs caused more severe damage to hepatocytes than when exposed to them alone concomitantly, exposed to Pb + MPs exhibited improved the levels of interleukin-6, tumor necrosis factor-alpha, and malondialdehyde, but reduced superoxide dismutase, glutathione peroxidase, and catalase assay in livers. Furthermore, they increase the Kelch-like ECH-associated protein 1 (Keap1) and phosphorylated p-NF-κB protein levels but reduced the protein levels of heme oxygenase-1 and Nrf2, as well as increased Keap1 mRNA and Nrf2 mRNA. Co-exposure to Pb + MP impacts glucose metabolism via the Nrf2 /NF-κB pathway.


Asunto(s)
FN-kappa B , Plásticos , Ratones , Animales , FN-kappa B/metabolismo , Plásticos/metabolismo , Plásticos/farmacología , Proteína 1 Asociada A ECH Tipo Kelch/genética , Proteína 1 Asociada A ECH Tipo Kelch/metabolismo , Factor 2 Relacionado con NF-E2/genética , Factor 2 Relacionado con NF-E2/metabolismo , Microplásticos , Plomo , Ratones Endogámicos C57BL , Estrés Oxidativo , ARN Mensajero/metabolismo , Glucosa/farmacología
11.
Chem Soc Rev ; 52(3): 1129-1154, 2023 Feb 06.
Artículo en Inglés | MEDLINE | ID: mdl-36722920

RESUMEN

Two-dimensional metallacycles and three-dimensional metallacages constructed by coordination-driven self-assembly have attracted much attention because they exhibit unique structures and properties and are highly efficient to synthesize. Introduction of switching into supramolecular chemistry systems is a popular strategy, as switching can endow systems with reversible features that are triggered by different stimuli. Through this strategy, novel switchable metallacycles and metallacages were generated, which can be reversibly switched into different stable states with distinct characteristics by external stimuli. Switchable metallacycles and metallacages exhibit versatile structures and reversible properties and are inherently dynamic and respond to artificial signals; thus, these structures have many promising applications in a wide range of fields, such as drug delivery, data processing, pollutant removal, switchable catalysis, smart functional materials, etc. This review focuses on the design of switchable metallacycles and metallacages, their switching behaviours and mechanisms triggered by external stimuli, and the corresponding structural changes and resultant properties and functions.

12.
Sensors (Basel) ; 24(8)2024 Apr 09.
Artículo en Inglés | MEDLINE | ID: mdl-38676004

RESUMEN

To monitor the position and profile of therapeutic carbon beams in real-time, in this paper, we proposed a system called HiBeam-T. The HiBeam-T is a time projection chamber (TPC) with forty Topmetal-II- CMOS pixel sensors as its readout. Each Topmetal-II- has 72 × 72 pixels with the size of 83 µm × 83 µm. The detector consists of the charge drift region and the charge collection area. The readout electronics comprise three Readout Control Modules and one Clock Synchronization Module. This Hibeam-T has a sensitive area of 20 × 20 cm and can acquire the center of the incident beams. The test with a continuous 80.55 MeV/u 12C6+ beam shows that the measurement resolution to the beam center could reach 6.45 µm for unsaturated beam projections.

13.
J Environ Manage ; 361: 121270, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38820796

RESUMEN

Reliable nitrogen (N) fertilizer management indicators are essential for improving crop yields and minimizing environmental impacts for sustainable production. The objectives of this study were to assess the importance of major N management indicators (NMIs) for higher yield with low risks of environmental pollution in an intensive potato system under drip irrigation. Six drip-irrigated field experiments with no N application (Control), farmer practice (FP), and optimized N management (OM) based on N-balance, soil mineral N (Nmin), and target yield were conducted from 2018 to 2020 in Inner Mongolia, China. The response of NMIs to potato yield and yield-based environment impact indices (EIY) was evaluated by the random forest algorithm. The N input, N losses from N leaching, ammonia (NH3) volatilization, nitrous oxide (N2O) emission, N use efficiency (NUE), N surplus, and soil residual N after harvest were obtained to identify the best NMIs for high yield and minimal ecological impact. The N management practices in field experimental sites affected the importance of the order of NMIs on potato yield and EIY. The NUE and N leaching were identified as the highest importance scores and the most essential controlling variables to potato yield and EIY, respectively. The integrated NUE and N leaching indicator played a vital role in improving potato yield and reducing ecological impact. The OM treatment achieved 46.0%, 63.6%, and 64.6% lower in N application rate, N surplus, and reactive N loss, and 62.4% higher in NUE than the FP treatment while achieving equal potato yields, respectively. Those key NMIs can guide farmers in understanding their practice short comes to achieve both high productivity and environmental sustainability in intensive potato production systems under drip irrigation.


Asunto(s)
Riego Agrícola , Producción de Cultivos , Fertilizantes , Nitrógeno , Suelo , Solanum tuberosum , Solanum tuberosum/crecimiento & desarrollo , Riego Agrícola/métodos , Producción de Cultivos/métodos , Suelo/química , China , Agricultura/métodos , Productos Agrícolas/crecimiento & desarrollo
14.
Wei Sheng Yan Jiu ; 53(2): 275-281, 2024 Mar.
Artículo en Zh | MEDLINE | ID: mdl-38604964

RESUMEN

OBJECTIVE: To investigate the content of rare earth elements(REs)in blood and hair of residents in a RE mining area in Northwest Hubei, and evaluate the impact of REs on the health status of local residents. METHODS: A total of 191 residents from the core area of RE mining areas and 186 residents from non RE mining areas, aged 20-69, were selected. The content of REs in the blood and hair of the survey subjects was measured using inductively coupled plasma mass spectrometry, and compared with existing literature values. At the same time, blood tests and questionnaire surveys will be conducted on the health status of residents to examine whether human RE enrichment can lead to endemic diseases. RESULTS: The average total content of REs in the blood of residents in the mining area was 60.22 ng/mL, which was 3.35 times that of the control area; The average total content of REs in hair was 1197.91 ng/g, which was 6.32 times higher than the control area. As age increasing, the abundance of REs in the blood and hair of both men and women in mining areas increased. The proportion of Yttrium and Scandium in the blood and hair were much higher than that in the soil. Compared to hair, Yttrium and Scandium were more easily enriched in the blood. There was no significant difference in the probability of fatty liver, hepatitis B, hypoglycemia, hypotension, hypertension and heart disease and the average life span between residents in RE mining areas and those in the control area. CONCLUSION: The high daily average dietary intake of REs in residents leads to a relatively large accumulation of REs in human blood and hair, but no significant and substantial human health damage has been found at present.


Asunto(s)
Hipertensión , Metales de Tierras Raras , Masculino , Humanos , Femenino , Escandio/análisis , Metales de Tierras Raras/análisis , Cabello/química , Itrio/análisis , China , Monitoreo del Ambiente
15.
Angew Chem Int Ed Engl ; : e202412548, 2024 Aug 13.
Artículo en Inglés | MEDLINE | ID: mdl-39136324

RESUMEN

Aiming at the further extension of the application scope of traditional molecular muscles, a novel bispyrene-functionalized chiral molecular [c2]daisy chain was designed and synthesized. Taking advantage of the unique dimeric interlocked structure of molecular [c2]daisy chain, the resultant chiral molecular muscle emits strong circularly polarized luminescence (CPL) attributed to the pyrene excimer with a high dissymmetry factor (glum) value of 0.010. More importantly, along with the solvent- or anion- induced motions of the chiral molecular muscle, the precise regulation of the pyrene stacking within its skeleton results in the switching towards either "inversed" state with sign inversion and larger glum values or "down" state with maintained handedness and smaller glum values, making it a novel multistate CPL switch. As the first example of chiral molecular muscle-based CPL switch, this proof-of-concept study not only successfully widens the application scopes of molecular muscles, but also provides a promising platform for the construction of novel smart chiral luminescent materials for practical applications.

16.
Angew Chem Int Ed Engl ; 63(37): e202408271, 2024 Sep 09.
Artículo en Inglés | MEDLINE | ID: mdl-38837513

RESUMEN

To explore the chirality induction and switching of topological chirality, poly[2]catenanes composed of helical poly(phenylacetylenes) (PPAs) main chain and topologically chiral [2]catenane pendants are described for the first time. These poly[2]catenanes with optically active [2]catenanes on side chains were synthesized by polymerization of enantiomerically pure topologically chiral [2]catenanes with ethynyl polymerization site and/or point chiral moiety. The chirality information of [2]catenane pendants was successfully transferred to the main chain of polyene backbones, leading to preferred-handed helical conformations, while the introduction of point chiral units has negligible effect on the overall helices. More interestingly, attributed to unique dynamic feature of the [2]catenane pendants, these polymers revealed dynamic response behaviors to solvents, temperature, and sodium ions, resulting in the fully reversible switching on/off of the chirality induction. This work provides not only new design strategy for novel chiroptical switches with topologically chiral molecules but also novel platforms for the development of smart chiral materials.

17.
Angew Chem Int Ed Engl ; 63(36): e202407279, 2024 Sep 02.
Artículo en Inglés | MEDLINE | ID: mdl-38872356

RESUMEN

Polyradical cages are of great interest because they show very fascinating physical and chemical properties, but many challenges remain, especially for their synthesis and characterization. Herein, we present the synthesis of a polyradical cation cage 14⋅+ through post-synthetic oxidation of a redox-active phenothiazine-based Pd2L4-type coordination cage 1. It's worth noting that 1 exhibits excellent reversible electrochemical and chemical redox activity due to the introduction of a bulky 3,5-di-tert-butyl-4-methoxyphenyl substituent. The generation of 14⋅+ through reversible electrochemical oxidation is investigated by in situ UV/Vis-NIR and EPR spectroelectrochemistry. Meanwhile, chemical oxidation of 1 can also produce 14⋅+ which can be reversibly reduced back to the original cage 1, and the process is monitored by EPR and NMR spectroscopies. Eventually, we succeed in the isolation and single crystal X-ray diffraction analysis of 14⋅+, whose electronic structure and conformation are distinct to original 1. The magnetic susceptibility measurements indicate the predominantly antiferromagnetic interactions between the four phenothiazine radical cations in 14⋅+. We believe that our study including the facile synthesis methodology and in situ spectroelectrochemistry will shed some light on the synthesis and characterization of novel polyradical systems, opening more perspectives for developing functional supramolecular cages.

18.
Angew Chem Int Ed Engl ; : e202409878, 2024 Jul 25.
Artículo en Inglés | MEDLINE | ID: mdl-39051526

RESUMEN

Investigating the self-sorting behaviour of assemblies with subtle structural differences is a captivating yet challenging endeavour. Herein, we elucidate the unusual self-sorting behaviour of metallacages with subtle structural differences in batch reactors and microdroplets. Narcissistic self-sorting of metallacages has been observed for two ligands with identical sizes, shapes, and symmetries, with only minor differences in the substituted groups. In particular, the self-sorting process in microdroplets occurs within 1 min at room temperature, in stark contrast to batch reactors, which require equilibration for 30 min. To reveal the mechanism of self-sorting and the role of microdroplets, we conducted a series of experiments and theoretical calculations, including competitive self-assembly, cage-to-cage transformation, control experiments involving model metallacages with larger cavities, noncovalent interaction analysis, and root mean square deviation (RMSD) analysis. This research demonstrates an unusual case of self-sorting of very similar assemblies and provides a new strategy for facilitating the self-sorting efficiency of supramolecular systems.

19.
Angew Chem Int Ed Engl ; : e202414089, 2024 Sep 02.
Artículo en Inglés | MEDLINE | ID: mdl-39221861

RESUMEN

The exploration of novel functionalized supramolecular coordination complexes (SCCs) can enable new applications in domains that include purification and sensing. In this study, employing a coordination-driven self-assembly strategy, we designed and prepared a series of benzochalcogenodiazole-based metallohelicates as high-efficiency charge transfer surface-enhanced Raman scattering (SERS) substrates, expanding the range of applications for these metallohelicates. Through structural modifications, including the substitution of single heteroatoms on ligands, replacement of coordinating metals, and alteration of ligand framework linkages, the Raman performance of these metallohelicates as substrates were systematically optimized. Notably, the SERS enhancement factors (EFs) of the metallohelicate-based SERS substrates were significantly enhanced to levels as high as 1.03 × 107, which rivals the EFs of noble metals devoid of "hot spots". Additionally, the underlying Raman enhancement mechanisms of these metallohelicates have been investigated through a combination of control experiments and theoretical calculations. This study not only demonstrates the utility of metallohelicates as SERS substrates but also offers insights and materials for the development of high-efficiency new charge transfer SERS substrates.

20.
Angew Chem Int Ed Engl ; : e202415190, 2024 Sep 11.
Artículo en Inglés | MEDLINE | ID: mdl-39258396

RESUMEN

As a novel type of macrocycles with attractive planar chirality, pillar[5]arenes have gained increasing research interest over the past decades, enabling their widespread applications in diverse fields such as porous materials, molecular machines, and chiral luminescence materials. However, the catalytic methodology towards the enantioselective synthesis of planar chiral pillar[5]arenes remains elusive. Here we report a novel method for the enantioselective synthesis of planar chiral pillar[5]arenes via asymmetric Sonogashira coupling, giving access to a wide range of highly functionalized planar chiral pillar[5]arenes, including both homo- and hetero-rimmed ones, with excellent enantioselectivities. Attractively, the resultant planar chiral pillar[5]arenes show great potential for widespread use in many areas such as chiral luminescent materials. This work not only enables the successful synthesis of planar chiral pillar[5]arenes with abundant structural and functional diversity as key building blocks for practical applications but also enriches the asymmetric cross-coupling methodologies in organic synthetic chemistry.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA