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1.
Dig Liver Dis ; 2024 May 07.
Artículo en Inglés | MEDLINE | ID: mdl-38719628

RESUMEN

BACKGROUND AND AIMS: Oxaliplatin (OX) has been described as a potential etiologic agent for porto-sinusoidal vascular disorder (PSVD). Our aim was to describe the natural history of PSVD due to OX in colon cancer (CRC) and identify risk factors for its development. METHODS: We made a multicenter retrospective case-control (ratio 1:3) study with patients diagnosed of PSVD-OX. Baseline data, end of treatment, years of follow-up and diagnosis of PSVD were collected and compared to controls (without PSVD). Besides, 16 different SNPs were selected from bibliography and analyzed by genotyping in the case group to identify potential genetic risk factors. RESULTS: 41 cases were identified, with a median time to PSVD diagnosis after the end of OX of 34 months. Spleen diameter was the strongest predictor of PSVD during treatment (OR 43.94 (14.48-133.336); p < 0.0001). Additionally, thrombocytopenia (<150 × 10^9) at one year was a significant disease risk marker (OR 9.35; 95% CI: 3.71-23.58; p = 0.001). We could not establish any significant association between the selected SNPs and PSVD diagnosis. CONCLUSION: The increase of spleen diameter is the strongest predictor of PSVD in patients treated with OX for CRC. These patients could be candidates for a specific follow-up of portal hypertension-related complications.

2.
Nat Commun ; 15(1): 3975, 2024 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-38729930

RESUMEN

Oxidoreductases have evolved tyrosine/tryptophan pathways that channel highly oxidizing holes away from the active site to avoid damage. Here we dissect such a pathway in a bacterial LPMO, member of a widespread family of C-H bond activating enzymes with outstanding industrial potential. We show that a strictly conserved tryptophan is critical for radical formation and hole transference and that holes traverse the protein to reach a tyrosine-histidine pair in the protein's surface. Real-time monitoring of radical formation reveals a clear correlation between the efficiency of hole transference and enzyme performance under oxidative stress. Residues involved in this pathway vary considerably between natural LPMOs, which could reflect adaptation to different ecological niches. Importantly, we show that enzyme activity is increased in a variant with slower radical transference, providing experimental evidence for a previously postulated trade-off between activity and redox robustness.


Asunto(s)
Proteínas Bacterianas , Oxigenasas de Función Mixta , Oxidación-Reducción , Oxigenasas de Función Mixta/metabolismo , Oxigenasas de Función Mixta/genética , Oxigenasas de Función Mixta/química , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/química , Dominio Catalítico , Triptófano/metabolismo , Polisacáridos/metabolismo , Mutación , Estrés Oxidativo , Tirosina/metabolismo , Modelos Moleculares , Histidina/metabolismo , Histidina/genética
3.
Biomed Pharmacother ; 175: 116668, 2024 May 02.
Artículo en Inglés | MEDLINE | ID: mdl-38701565

RESUMEN

The combination of radiation treatment and chemotherapy is currently the standard for management of cancer patients. However, safe doses do not often provide effective therapy, then pre-treated patients are forced to repeat treatment with often already increased tumor resistance to drugs and irradiation. One of the solutions we suggest is to improve primary course of radiation treatment via enhancing radiosensitivity of tumors by magnetic-guided iron oxide nanoparticles (magnetite). We obtained spherical heparinized iron oxide nanoparticles (hIONPs, ∼20 nm), characterized it by TEM, Infrared spectroscopy and DLS. Then hIONPs cytotoxicity was assessed for colon cancer cells (XTT assay) and cellular uptake of nanoparticles was analyzed with X-ray fluorescence. Combination of ionizing radiation (IR) and hIONPs in vitro caused an increase of G2/M arrest of cell cycle, mitotic errors and decrease in survival (compared with samples exposed to IR and hIONPs separately). The promising results were shown for magnetic-guided hIONPs in CT26-grafted BALB/C mice: the combination of intravenously administrated hIONPs and IR showed 20,8% T/C ratio (related to non-treated mice), while single radiation had no shown significant decrease in tumor growth (72,4%). Non-guided by magnets hIONPs with IR showed 57,9% of T/C. This indicates that ultra-small size and biocompatible molecule are not the key to successful nano-drug design, in each case, delivery technologies need to be improved when transferred to in vivo model.

4.
Chemistry ; : e202400828, 2024 Apr 19.
Artículo en Inglés | MEDLINE | ID: mdl-38640462

RESUMEN

Pyridoxal hydrochloride, a vitamin B6 vitamer, was synthetically converted to a series of diverse redox-active benzoyl pyridinium salts. Cyclic voltammetry studies demonstrated redox reversibility under basic conditions, and two of the most promising salts were subjected to laboratory-scale redox flow battery tests involving galvanostatic cycling at 10 mM in 0.1 M NaOH. In these tests, the battery was charged completely, corresponding to the transfer of two electrons to the electrolyte, but no discharge was observed. Both CV analysis and electrochemical simulations confirmed that the redox wave observed in the experimental voltammograms corresponds to a two-electron process. To explain the irreversibility in the battery tests, we conducted bulk electrolysis with the benzoyl pyridinium salts, affording the corresponding benzylic secondary alcohols. Computational studies suggest that the reduction proceeds in three consecutive steps: first electron transfer (ET), then proton-coupled electron transfer (PCET) and finally proton transfer (PT) to give the secondary alcohol. 1H NMR deuterium exchange studies indicated that the last PT step is not reversible in 0.1 M NaOH, rendering the entire redox process irreversible. The apparent reversibility observed in CV at the basic media likely arises from the slow rate of the PT step at the timescale of the measurement.

5.
Psychol Assess ; 2024 Apr 08.
Artículo en Inglés | MEDLINE | ID: mdl-38587942

RESUMEN

The International Classification of Diseases, 11th edition (ICD-11) adopted a fully dimensional model of personality disorder. The Personality Inventory for ICD-11 (PiCD) and Informant-Personality Inventory for ICD-11 (IPiC) were developed to assess the ICD-11 trait model, and the PiCD has since received significant validation support. However, there has only been one prior study of longitudinal predictive validity of the PiCD, two relatively short test-retest reliability studies of the PiCD, and no prior longitudinal tests of the IPiC. Longitudinal psychometric support for psychological assessment measures is essential. The present study provides a longer, larger, 2-year psychometric validation test of the PiCD and IPiC. Participants (N = 711) and their informants (N = 569) were recruited in the St. Louis Personality and Aging Network. The results demonstrated strong 2-year retest reliability for the PiCD and IPiC, as well as mean-level stability. Additionally, we explored the relationships between the PiCD and IPiC and important life outcome measures (depressive symptoms, satisfaction with life, and health status). The analysis revealed several significant associations between PiCD and IPiC scales and the outcome variables across time. Further, the PiCD Negative Affectivity and IPiC Detachment scales demonstrated incremental validity over each other and the outcome variables at Wave 1 in the prediction of depressive symptoms and satisfaction with life, respectively. The findings provide essential longitudinal test-retest reliability and predictive validity support for the PiCD and IPiC. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

6.
Artículo en Inglés | MEDLINE | ID: mdl-38644419

RESUMEN

PURPOSE: The purpose of our work was to demonstrate the surgical technique of ankle arthrodesis using the minimally-invasive transfibular (MITF) approach, which minimizes soft tissue damage and is advantageous for high-risk patients. METHODS: In this prospective study, a total of 12 patients with end-stage varus ankle osteoarthritis, including high-risk individuals, underwent ankle arthrodesis using the MITF approach. The technique involves a unique osteotomy at the joint space level, minimizing soft tissue detachment from the fibula. The primary outcomes assessed included bony union, time to weight-bearing, correction of varus deformity, and functional outcomes measured by the American Orthopedic Foot and Ankle Society (AOFAS) hindfoot scale. However, the study's limitations encompass a small sample size and the absence of a control group. RESULTS: At 6 months post-operation, all patients achieved bony union, with a mean time to union of 13.7 ± 5.2 weeks. The average time to initiate weight-bearing without additional support was 11.2 ± 3.8 weeks. Preoperative varus deformity (17.08 ± 8.36 degrees) and talar tilt (8.75 ± 4.33 degrees) were successfully corrected, with postoperative alignment within 0-5 degrees of valgus. Functional outcomes showed a significant improvement in AOFAS scores from 37.83 ± 7.79 points preoperatively to 77.42 ± 5.63 points one year after surgery (p = 0.002). Minor complications occurred in two patients, both effectively treated with local therapy and antibiotics. CONCLUSIONS: The MITF approach for ankle arthrodesis demonstrates promising results in addressing end-stage varus ankle osteoarthritis, even in high-risk patients. However, the study's limitations highlight the need for a prospective comparative clinical trial with a larger sample size to ascertain the technique's effectiveness and safety definitively.

7.
Biomimetics (Basel) ; 9(4)2024 Apr 19.
Artículo en Inglés | MEDLINE | ID: mdl-38667259

RESUMEN

Soft robotics is closely related to embodied intelligence in the joint exploration of the means to achieve more natural and effective robotic behaviors via physical forms and intelligent interactions. Embodied intelligence emphasizes that intelligence is affected by the synergy of the brain, body, and environment, focusing on the interaction between agents and the environment. Under this framework, the design and control strategies of soft robotics depend on their physical forms and material properties, as well as algorithms and data processing, which enable them to interact with the environment in a natural and adaptable manner. At present, embodied intelligence has comprehensively integrated related research results on the evolution, learning, perception, decision making in the field of intelligent algorithms, as well as on the behaviors and controls in the field of robotics. From this perspective, the relevant branches of the embodied intelligence in the context of soft robotics were studied, covering the computation of embodied morphology; the evolution of embodied AI; and the perception, control, and decision making of soft robotics. Moreover, on this basis, important research progress was summarized, and related scientific problems were discussed. This study can provide a reference for the research of embodied intelligence in the context of soft robotics.

8.
Int J Mol Sci ; 25(8)2024 Apr 11.
Artículo en Inglés | MEDLINE | ID: mdl-38673819

RESUMEN

Perineuronal nets (PNN) are a special highly structured type of extracellular matrix encapsulating synapses on large populations of CNS neurons. PNN undergo structural changes in schizophrenia, epilepsy, Alzheimer's disease, stroke, post-traumatic conditions, and some other brain disorders. The functional role of the PNN microstructure in brain pathologies has remained largely unstudied until recently. Here, we review recent research implicating PNN microstructural changes in schizophrenia and other disorders. We further concentrate on high-resolution studies of the PNN mesh units surrounding synaptic boutons to elucidate fine structural details behind the mutual functional regulation between the ECM and the synaptic terminal. We also review some updates regarding PNN as a potential pharmacological target. Artificial intelligence (AI)-based methods are now arriving as a new tool that may have the potential to grasp the brain's complexity through a wide range of organization levels-from synaptic molecular events to large scale tissue rearrangements and the whole-brain connectome function. This scope matches exactly the complex role of PNN in brain physiology and pathology processes, and the first AI-assisted PNN microscopy studies have been reported. To that end, we report here on a machine learning-assisted tool for PNN mesh contour tracing.


Asunto(s)
Inteligencia Artificial , Encéfalo , Matriz Extracelular , Humanos , Encéfalo/patología , Encéfalo/diagnóstico por imagen , Matriz Extracelular/metabolismo , Animales , Microscopía/métodos , Red Nerviosa/patología , Sinapsis/patología , Encefalopatías/patología , Neuronas/patología , Neuronas/metabolismo
9.
Chempluschem ; : e202400029, 2024 Apr 08.
Artículo en Inglés | MEDLINE | ID: mdl-38589286

RESUMEN

Continuing our investigation of catalytic oxo/imido heterometathesis as novel water-free method for C=N bond construction, we report here the application of classical transition metal oxides dispersed on silica (MOx/SiO2, M=V, Mo, W) as cheap, robust and readily available alternative to the catalysts prepared via Surface Organometallic Chemistry (SOMC). The oxide materials demonstrated activity in heterometathetical imidation of ketones, WO3/SiO2 being the most efficient. We also describe a new well-defined supported W imido complex (≡SiO)W(=NMes)2(Me2Pyr) (Mes=2,4,6-Me3C6H2, Me2Pyr=2,5-dimethylpyrrolyl) and characterize it with SOMC protocols, which allowed us to identify the position of W on the oxo/imido heterometathesis activity scale (Mo

10.
J Org Chem ; 89(9): 6602-6606, 2024 May 03.
Artículo en Inglés | MEDLINE | ID: mdl-38635314

RESUMEN

Oxidation of 2-furylaninlies with m-CPBA followed by treatment with a base provides access to functionalized indolin-3-ones. The designed oxidative transformation utilizes an underassessed chemical behavior of furyl-containing amines to form a C-N bond via engaging a ß-carbon atom of the furan core upon a ring-forming step, thereby providing an alternative disconnection toward nitrogen-containing heterocycles.

11.
Adv Sci (Weinh) ; : e2307060, 2024 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-38516744

RESUMEN

Biodegradable nanomaterials can significantly improve the safety profile of nanomedicine. Germanium nanoparticles (Ge NPs) with a safe biodegradation pathway are developed as efficient photothermal converters for biomedical applications. Ge NPs synthesized by femtosecond-laser ablation in liquids rapidly dissolve in physiological-like environment through the oxidation mechanism. The biodegradation of Ge nanoparticles is preserved in tumor cells in vitro and in normal tissues in mice with a half-life as short as 3.5 days. Biocompatibility of Ge NPs is confirmed in vivo by hematological, biochemical, and histological analyses. Strong optical absorption of Ge in the near-infrared spectral range enables photothermal treatment of engrafted tumors in vivo, following intravenous injection of Ge NPs. The photothermal therapy results in a 3.9-fold reduction of the EMT6/P adenocarcinoma tumor growth with significant prolongation of the mice survival. Excellent mass-extinction of Ge NPs (7.9 L g-1 cm-1 at 808 nm) enables photoacoustic imaging of bones and tumors, following intravenous and intratumoral administrations of the nanomaterial. As such, strongly absorbing near-infrared-light biodegradable Ge nanomaterial holds promise for advanced theranostics.

12.
Biomolecules ; 14(3)2024 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-38540716

RESUMEN

The severity of COVID-19 is linked to an imbalanced immune response. The dysregulated metabolism of small molecules and bioactive lipids has also been associated with disease severity. To promote understanding of the disease biochemistry and provide targets for intervention, we applied a range of LC-MS platforms to analyze over 100 plasma samples from patients with varying COVID-19 severity and with detailed clinical information on inflammatory responses (>30 immune markers). This is the third publication in a series, and it reports the results of comprehensive lipidome profiling using targeted LC-MS/MS. We identified 1076 lipid features across 25 subclasses, including glycerophospholipids, sterols, glycerolipids, and sphingolipids, among which 531 lipid features were dramatically changed in the plasma of intensive care unit (ICU) patients compared to patients in the ward. Patients in the ICU showed 1.3-57-fold increases in ceramides, (lyso-)glycerophospholipids, diglycerides, triglycerides, and plasmagen phosphoethanolamines, and 1.3-2-fold lower levels of a cyclic lysophosphatidic acid, sphingosine-1-phosphates, sphingomyelins, arachidonic acid-containing phospholipids, lactosylceramide, and cholesterol esters compared to patients in the ward. Specifically, phosphatidylinositols (PIs) showed strong fatty acid saturation-dependent behavior, with saturated fatty acid (SFA)- and monosaturated fatty acid (MUFA)-derived PI decreasing and polystaturated (PUFA)-derived PI increasing. We also found ~4000 significant Spearman correlations between lipids and multiple clinical markers of immune response with |R| ≥ 0.35 and FDR corrected Q < 0.05. Except for lysophosphatidic acid, lysophospholipids were positively associated with the CD4 fraction of T cells, and the cytokines IL-8 and IL-18. In contrast, sphingosine-1-phosphates were negatively correlated with innate immune markers such as CRP and IL-6. Further indications of metabolic changes in moderate COVID-19 disease were demonstrated in recovering ward patients compared to those at the start of hospitalization, where 99 lipid species were altered (6 increased by 30-62%; 93 decreased by 1.3-2.8-fold). Overall, these findings support and expand on early reports that dysregulated lipid metabolism is involved in COVID-19.


Asunto(s)
COVID-19 , Esfingosina/análogos & derivados , Humanos , Lipidómica , Cromatografía Liquida , Espectrometría de Masas en Tándem , Ácidos Grasos/metabolismo , Glicerofosfolípidos , Lisofosfolípidos , Biomarcadores , Gravedad del Paciente , Fosfatos
13.
Dalton Trans ; 53(12): 5567-5579, 2024 Mar 19.
Artículo en Inglés | MEDLINE | ID: mdl-38426897

RESUMEN

In this contribution we report the synthesis, characterization and in vitro anticancer activity of novel cyclometalated 4-phenylthiazole-derived ruthenium(II) (2a-e) and osmium(II) (3a-e) complexes. Formation and sufficient purity of the complexes were unambigiously confirmed by 1H-, 13C- and 2D-NMR techniques, X-ray diffractometry, HRMS and elemental analysis. The binding preferences of these cyclometalates to selected amino acids and to DNA models including G-quadruplex structures were analyzed. Additionally, their stability and behaviour in aqueous solutions was determined by UV-Vis spectroscopy. Their cellular accumulation, their ability of inducing apoptosis, as well as their interference in the cell cycle were studied in SW480 colon cancer cells. The anticancer potencies were investigated in three human cancer cell lines and revealed IC50 values in the low micromolar range, in contrast to the biologically inactive ligands.


Asunto(s)
Antineoplásicos , Complejos de Coordinación , Rutenio , Humanos , Estructura Molecular , Modelos Moleculares , Línea Celular Tumoral , Antineoplásicos/química , Ciclo Celular , Rutenio/farmacología , Rutenio/química , Complejos de Coordinación/química
14.
Inorg Chem ; 63(11): 5083-5097, 2024 Mar 18.
Artículo en Inglés | MEDLINE | ID: mdl-38453174

RESUMEN

Zeolites modified with metal cations are perspective catalysts for converting light alkenes to valuable chemicals. A crucial step of the transformation is an alkene interaction with zeolite to afford π-complex with metal cations. The mechanism of alkene bonding with cations is still unclear. To address this problem, propene adsorption on H+ (BroÌ·nsted acid site), Na+, Ca2+, Zn2+, Co2+, Cu2+, Cu+, and Ag+ cationic sites in ZSM-5 zeolite has been studied by quantum chemical calculations in terms of adsorption enthalpy, νC═C frequency, and natural bond orbital (NBO) analysis together with natural energy decomposition analysis (NEDA). It is revealed that the conventional concept of σ- and π-bonding is only partially applicable to alkene interaction with metal cations in zeolites. The orbital interaction between an alkene molecule and a metal site is more complex. Several different bonding mechanisms have been identified depending on the nature and electron configuration of the metal cation. This finding explains the complex correlations observed for propene π-complex stability and νC═C frequency shift or charge transfer from the alkene molecule. The results provide the basis for further understanding the interactions between alkenes and inorganic solid BroÌ·nsted and Lewis acids.

15.
Org Biomol Chem ; 22(13): 2643-2653, 2024 03 27.
Artículo en Inglés | MEDLINE | ID: mdl-38456317

RESUMEN

Thienylallylamines, readily accessible from the corresponding thienyl aldehydes, react with maleic and trifluoromethylmaleic anhydrides leading to the formation of acids with a thieno[2,3-f]isoindole core. The reaction sequence involves two successive steps: acylation of the nitrogen atom of the initial allylamine and the intramolecular Diels-Alder vinylarene (IMDAV) reaction. The scope and limitations of the proposed method were thoroughly investigated. It has been revealed with the aid of X-ray analysis and DFT calculations that the key step, the IMDAV reaction, proceeds through an exo-transition state, giving rise to the exclusive formation of a single diastereomer of the target heterocycle. The obtained functionally substituted thieno[2,3-f]isoindole carboxylic acids are potentially useful substrates for further transformations and bioscreening. The antimicrobial evaluation of the obtained compounds revealed that 1-oxo-2-(3-(trifluoromethyl)phenyl)hexahydrobenzo[4,5]thieno[2,3-f]isoindole-10-carboxylic acid is the most active sample in the synthesized library. It exhibits antibacterial activity against sensitive strains of Gram-positive bacteria, including S. aureus, Enterococcus faecium, Bacillus cereus, and Micrococcus luteus, as well as the Gram-negative bacteria E. coli and Pseudomonas fluorescens, with MIC values ranging from 4 to 64 µg mL-1. 9-Oxo-8-phenyloctahydronaphtho[2,1-d]thieno[2,3-f]isoindole-10-carboxylic acid showed antifungal activity against yeast culture C. albicans with a MIC value of 32 µM.


Asunto(s)
Escherichia coli , Staphylococcus aureus , Pruebas de Sensibilidad Microbiana , Antibacterianos/química , Ácidos Carboxílicos , Isoindoles
16.
Nat Commun ; 15(1): 1914, 2024 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-38429287

RESUMEN

Oceanic transform faults play an essential role in plate tectonics. Yet to date, there is no unifying explanation for the global trend in broad-scale transform fault topography, ranging from deep valleys to shallow topographic highs. Using three-dimensional numerical models, we find that spreading-rate dependent magmatism within the transform domain exerts a first-order control on the observed spectrum of transform fault depths. Low-rate magmatism results in deep transform valleys caused by transform-parallel tectonic stretching; intermediate-rate magmatism fully accommodates far-field stretching, but strike-slip motion induces across-transform tension, producing transform strength dependent shallow valleys; high-rate magmatism produces elevated transform zones due to local compression. Our models also address the observation that fracture zones are consistently shallower than their adjacent transform fault zones. These results suggest that plate motion change is not a necessary condition for reproducing oceanic transform topography and that oceanic transform faults are not simple conservative strike-slip plate boundaries.

17.
Biomedicines ; 12(3)2024 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-38540166

RESUMEN

The gut microbiota plays an important role in maintaining human health, as well as in the development of various pathologies, as indicated by a large amount of research. One of the manifestations of an imbalance in the gut microbiome composition is the appearance of various diseases or immune reactions, in particular, atopic dermatitis (AD) and/or food allergies (FA). In this research, using 16S NGS sequencing, it was found that the gut microbiome of children with food allergies and children with atopic dermatitis can be characterized as having higher inflammatory potential. Both groups exhibited an abundance of representatives from the Pasteurellaceae and Erysipelotrichaceae families, as well as a decrease in the relative number of representatives from the Barnesiellaceae family compared to healthy participants. In the group of participants with food allergies, there was a decrease in the relative number of Desulfovibrionaceae representatives and Bifidobacteriaceae family enrichment in relatively healthy participants. In addition, when comparing this group with patients with atopic dermatitis, it was revealed that a number of representatives of such families as Erysipelotrichaceae, Ruminococcaceae and Sutterellaceae prevailed. This information confirms that AD and FA correlate with changes in the composition of the gut microbiota. Further research is needed to determine the cause-effect connections and the effect of compounds derived from the microbiota on the AD and FA development and progression, as well as to create new probiotic drugs to prevent and modulate immune responses, including at an early age.

18.
Nat Commun ; 15(1): 2225, 2024 Mar 12.
Artículo en Inglés | MEDLINE | ID: mdl-38472177

RESUMEN

Single-particle cryo-EM is widely used to determine enzyme-nucleosome complex structures. However, cryo-EM sample preparation remains challenging and inconsistent due to complex denaturation at the air-water interface (AWI). Here, to address this issue, we develop graphene-oxide-coated EM grids functionalized with either single-stranded DNA (ssDNA) or thiol-poly(acrylic acid-co-styrene) (TAASTY) co-polymer. These grids protect complexes between the chromatin remodeler SNF2h and nucleosomes from the AWI and facilitate collection of high-quality micrographs of intact SNF2h-nucleosome complexes in the absence of crosslinking. The data yields maps ranging from 2.3 to 3 Å in resolution. 3D variability analysis reveals nucleotide-state linked conformational changes in SNF2h bound to a nucleosome. In addition, the analysis provides structural evidence for asymmetric coordination between two SNF2h protomers acting on the same nucleosome. We envision these grids will enable similar detailed structural analyses for other enzyme-nucleosome complexes and possibly other protein-nucleic acid complexes in general.


Asunto(s)
Grafito , Nucleosomas , Grafito/química , Microscopía por Crioelectrón , Agua
19.
Dalton Trans ; 53(11): 4976-4983, 2024 Mar 12.
Artículo en Inglés | MEDLINE | ID: mdl-38393646

RESUMEN

We investigate Ti(NEt2)4 supported on silica dehydroxylated at 700 °C as an easily accessible pre-catalyst for oxo/imido heterometathesis reactions. Being activated with TolNH2, the supported Ti amide (SiO)Ti(NEt2)3 (1) demonstrates catalytic activity in the imidation of ketones with N-sulfinylamines comparable with the most active previously described well-defined imido catalyst (SiO)Ti(NtBu)(Me2Pyr)(py)2 (2) (Me2Pyr = 2,5-dimethylpyrrolyl), which implies the in situ formation of surface imido species in this system. The materials obtained via treatment of 1 with anilines (TolNH2 (1a) and p-MeOC6H415NH2 (1b)) were studied with IR, EA and 1H, 13C, 15N and 2D solid-state NMR, although the proposed imido intermediate has not been detected, pointing towards tris-amides (SiO)Ti(NHC6H4X)3 (X = Me, OMe) being the major surface species in the isolated materials 1a and 1b. The system 1/TolNH2 was tested in a range of imidation reactions and demonstrated excellent performance for express high-yielding preparation of ketimines, formamidines, lactone imidates and sulfurdiimines, making it a convenient alternative to the well-defined supported Ti imido catalysts.

20.
Int J Mol Sci ; 25(4)2024 Feb 08.
Artículo en Inglés | MEDLINE | ID: mdl-38396739

RESUMEN

The cis- and trans-isomers of 6-(3-(3,4-dichlorophenyl)-1,2,4-oxadiazol-5-yl)cyclohex-3-ene-1-carboxylic acid (cis-A and trans-A) were obtained by the reaction of 3,4-dichloro-N'-hydroxybenzimidamide and cis-1,2,3,6-tetrahydrophthalic anhydride. Cocrystals of cis-A with appropriate solvents (cis-A‧½(1,2-DCE), cis-A‧½(1,2-DBE), and cis-A‧½C6H14) were grown from 1,2-dichloroethane (1,2-DCE), 1,2-dibromoethane (1,2-DBE), and a n-hexane/CHCl3 mixture and then characterized by X-ray crystallography. In their structures, cis-A is self-assembled to give a hybrid 2D supramolecular organic framework (SOF) formed by the cooperative action of O-H⋯O hydrogen bonding, Cl⋯O halogen bonding, and π⋯π stacking. The self-assembled cis-A divides the space between the 2D SOF layers into infinite hollow tunnels incorporating solvent molecules. The energy contribution of each noncovalent interaction to the occurrence of the 2D SOF was verified by several theoretical approaches, including MEP and combined QTAIM and NCIplot analyses. The consideration of the theoretical data proved that hydrogen bonding (approx. -15.2 kcal/mol) is the most important interaction, followed by π⋯π stacking (approx. -11.1 kcal/mol); meanwhile, the contribution of halogen bonding (approx. -3.6 kcal/mol) is the smallest among these interactions. The structure of the isomeric compound trans-A does not exhibit a 2D SOF architecture. It is assembled by the combined action of hydrogen bonding and π⋯π stacking, without the involvement of halogen bonds. A comparison of the cis-A structures with that of trans-A indicated that halogen bonding, although it has the lowest energy in cis-A-based cocrystals, plays a significant role in the crystal design of the hybrid 2D SOF. The majority of the reported porous halogen-bonded organic frameworks were assembled via iodine and bromine-based contacts, while chlorine-based systems-which, in our case, are structure-directing-were unknown before this study.


Asunto(s)
Halógenos , Yodo , Hidrógeno , Bromo , Cloro , Solventes
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