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2.
Biomed Pharmacother ; 137: 111313, 2021 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-33556871

RESUMO

The SARS-CoV-2 outbreak and pandemic that began near the end of 2019 has posed a challenge to global health. At present, many candidate small-molecule therapeutics have been developed that can inhibit both the infection and replication of SARS-CoV-2 and even potentially relieve cytokine storms and other related complications. Meanwhile, host-targeted drugs that inhibit cellular transmembrane serine protease (TMPRSS2) can prevent SARS-CoV-2 from entering cells, and its combination with chloroquine and dihydroorotate dehydrogenase (DHODH) inhibitors can limit the spread of SARS-CoV-2 and reduce the morbidity and mortality of patients with COVID-19. The present article provides an overview of these small-molecule therapeutics based on insights from medicinal chemistry research and focuses on RNA-dependent RNA polymerase (RdRp) inhibitors, such as the nucleoside analogues remdesivir, favipiravir and ribavirin. This review also covers inhibitors of 3C-like protease (3CLpro), papain-like protease (PLpro) and other potentially innovative active ingredient molecules, describing their potential targets, activities, clinical status and side effects.

3.
Arch Virol ; 2021 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-33616726

RESUMO

In this study, a novel mitovirus designed "Colletotrichum higginsianum mitovirus 1" (ChMV1) was isolated from the phytopathogenic fungus Colletotrichum higginsianum. The genome of this mitovirus is 2,893 nt in length with an A + U content of 61% and contains a large open reading frame (ORF) encoding an RNA-dependent RNA polymerase (RdRp). A BLASTp analysis revealed that the RdRp domain of ChMV1 had 30.25% to 61.72% sequence identity to those of members of the genus Mitovirus and showed the highest degree of similarity (61.72% identity) to Botrytis cinerea mitovirus 3 (BcMV3). Phylogenetic analysis further indicated that ChMV1 is a member in the genus Mitovirus of the family Mitoviridae. To the best of our knowledge, this is the first report of a mitovirus in C. higginsianum.

4.
Front Immunol ; 12: 631044, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33613576

RESUMO

The coronavirus disease 2019 (COVID-19) pandemic has been raging around the world since January 2020. Pregnancy places the women in a unique immune scenario which may allow severe COVID-19 disease. In this regard, the potential unknown effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on mothers and fetuses have attracted considerable attention. There is no clear consistent evidence of the changes in the immune status of pregnant women after recovery from COVID-19. In this study, we use multiparameter flow cytometry and Luminex assay to determine the immune cell subsets and cytokines, respectively, in the peripheral blood and umbilical cord blood from pregnant women recovering from COVID-19 about 3 months (n=5). Our results showed decreased percentages of Tc2, Tfh17, memory B cells, virus-specific NK cells, and increased percentages of naive B cells in the peripheral blood. Serum levels of IL-1ra and MCP-1 showed a decreased tendency in late recovery stage (LRS) patients. Meanwhile, there was no significant difference in immune cell subsets in the umbilical cord blood. The placentas from LRS patients showed increased CD68+ macrophages infiltration and mild hypoxic features. The inflammatory damage of the placenta may be related to the antiviral response. Since the receptors, ACE2 and TMPRSS2, utilized by SARS-CoV-2 are not co-expressed in the placenta, so it is extremely rare for SARS-CoV-2 to cause infection through this route and the impact on the fetus is negligible.

5.
J Ethnopharmacol ; 271: 113895, 2021 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-33524512

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: Ginkgo biloba L. fruit, also known as Bai Guo, Ya Jiao Zi (in pinyin Chinese), and ginkgo nut (in English), has been used for many years as an important material in Chinese traditional medicine to treat coughs and asthma and as a disinfectant, as described in the Compendium of Materia Medica (Ben Cao Gang Mu, pinyin in Chinese), an old herbal book. Ginkgo nuts are used to treat phlegm-associated asthma, astringent gasp, frequent urination, gonorrhoea and turgidity; consumed raw to reduce phlegm and treat hangovers; and used as a disinfectant and insecticide. A similar record was also found in Sheng Nong's herbal classic (Shen Nong Ben Cao Jing, pinyin in Chinese). Recent research has shown that Ginkgo biloba L. exocarp extract (GBEE) can unblock blood vessels and improve brain function and exhibits antitumour and antibacterial activities. AIM OF STUDY: To investigate the inhibitory effect of Ginkgo biloba L. exocarp extract (GBEE) on methicillin-resistant S. aureus (MRSA) biofilms and assess its associated molecular mechanism. MATERIALS AND METHODS: The antibacterial effects of GBEE on S. aureus and MRSA were determined using the broth microdilution method. The growth curves of bacteria treated with or without GBEE were generated by measuring the CFU (colony forming unit) of cultures at different time points. The effects of GBEE on bacterial biofilm formation and mature biofilm disruption were determined by crystal violet staining. Quantitative polymerase chain reaction (qPCR) was used to measure the effects of GBEE on the gene expression profiles of MRSA biofilm-related factors at 6, 8, 12, 16 and 24 h. RESULTS: The minimum inhibitory concentration (MIC) of GBEE on S. aureus and MRSA was 4 µg/mL, and the minimum bactericidal concentration (MBC) was 8 µg/ml. Moreover, GBEE (4-12 µg/mL) inhibited S. aureus and MRSA biofilm formation in a dose-dependent manner. Interestingly, GBEE also destroyed mature biofilms of S. aureus and MRSA at 12 µg/ml. The expression of the MRSA biofilm-associated factor icaA and sarA were downregulated after 6 h of treatment with GBEE, while sigB was downregulated after 12 h. MeanwhileMeanwhile, icaR was upregulated at 12 h. In addition, GBEE also downregulated the virulence gene hld and inhibited the synthesis of staphyloxanthin. CONCLUSIONS: GBEE has excellent antibacterial effects against S. aureus and MRSA and inhibits their biofilm-forming ability by altering related gene expression.

6.
Eur J Med Chem ; 213: 113201, 2021 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-33524687

RESUMO

The widespread nature of several viruses is greatly credited to their rapidly altering RNA genomes that enable the infection to persist despite challenges presented by host cells. Within the RNA genome of infections is RNA-dependent RNA polymerase (RdRp), which is an essential enzyme that helps in RNA synthesis by catalysing the RNA template-dependent development of phosphodiester bonds. Therefore, RdRp is an important therapeutic target in RNA virus-caused diseases, including SARS-CoV-2. In this review, we describe the promising RdRp inhibitors that have been launched or are currently in clinical studies for the treatment of RNA virus infections. Structurally, nucleoside inhibitors (NIs) bind to the RdRp protein at the enzyme active site, and nonnucleoside inhibitors (NNIs) bind to the RdRp protein at allosteric sites. By reviewing these inhibitors, more precise guidelines for the development of more promising anti-RNA virus drugs should be set, and due to the current health emergency, they will eventually be used for COVID-19 treatment.

7.
Ticks Tick Borne Dis ; 12(3): 101679, 2021 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-33578256

RESUMO

Ticks and tick-borne rickettsial diseases have been gaining greater attention in China over the past decade. However, most published studies to date have occurred in Northern China, with limited investigations occurring in China's southern provinces. As part of larger surveillance efforts, a cross-sectional survey was conducted in six sites at Guangdong, Guangxi and Yunnan investigating rickettsial infection in ticks. A total of 581 ticks were collected from hosts and screened via PCR, targeting rrs, gltA, ompB, sca4, and ompA gene fragments. Two of 12 Haemaphysalis formosensis ticks were infected with novel Rickettsia strain GD01, which was closest phylogenetically (97.3-98.9 % identity) to Rickettsia tamurae strain AT-1, but not within the same clade. Another detected strain (GD02) shared similar identity, 99-100 % across four gene targets, to recently detected Candidatus Rickettsia longicornii isolate ROK-HL727, with an overall prevalence of 12.5 % (71/569). The presence of such pathogens calls for increased public health attention and active surveillance in patients reporting recent tick bites.

8.
Eur J Med Chem ; 215: 113274, 2021 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-33592537

RESUMO

Ceramides have emerged as potential therapeutic option with novel mechanism to affect the proliferation, differentiation, senescence, and apoptosis of cancer cells through regulation of multiple signal transduction. Aiming at the improvement of the apoptosis activity and pharmacokinetic profiles of ceramides, a novel series of ceramide analogs were developed through structure simplification and conformation restriction. Among them, compound 12 bearing an alkoxyl naphthyl motif, with favorable rat pharmacokinetic properties, showed better anti-proliferative activity against various colon cancer cells (IC50 ∼20 µM) than other ceramide analogues, as well as the synergistic effect combined with AKT inhibitor MK2206. Additionally, we demonstrated that this combination therapy promoted caspase 3-dependent apoptotic pathway and intensified cell cycle arrest in the G0/G1 phase. Furthermore, the combination of compound 12 and MK2206 displayed synergistic anti-tumor effect in vivo.

9.
Biomed Res Int ; 2021: 5545078, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33628789

RESUMO

Objective: Psychological status plays a vital role in the recovery in young ischemic stroke patients. However, few reports on the psychological symptoms in Chinese young ischemic stroke patients have been published. In the present study, we aimed to outline the psychological status of young ischemic stroke patients and its risk factors at three months after their stroke. Methods: 364 patients with young ischemic stroke and 384 age-matched healthy controls were consecutively recruited from our study hospitals of the mainland of China between June 2018 and November 2020. Social demographic and clinical data were collected from all enrolled participants in the acute stage of their stroke, and their psychological variables were assessed via the Symptom Checklist 90 Revised (SCL-90-R) at three-month timepoint after their stroke. Multivariable logistic regression analyses were run to identify the independent factors for psychological variables in patients. Results: Compared with healthy controls, patients with young ischemic stroke had significantly higher total score of SCL-90-R and all subscale total scores (p < 0.01 or 0.05). 22.3% (81/364 cases) in young ischemic stroke patients had psychological abnormalities. Compared with young ischemic stroke patients without psychological symptoms (n = 283), patients with psychological symptoms (n = 81) had higher rate of married status (p = 0.03), rate of hypertension (p = 0.01), infarct size (p = 0.01), and the family dysfunction (p < 0.01). Multivariate logistic regression analyses revealed that the family dysfunction (odds ratio [OR], 2.50, 95% confidence interval [CI]: 1.71 to 3.54, p < 0.01), having hypertension (OR, 3.27, 95% CI: 1.92 to 4.27, p = 0.02), and ≥20mm3 infarct size (OR, 2.39, 95% CI: 1.53 to 3.45, p < 0.01) were independent factors for having psychological abnormalities in patients with young ischemic stroke at three months after their stroke. Single (OR, 1.23, 95% CI: 1.03 to 1.54, p = 0.01), poor family function (OR, 1.21, 95% CI: 1.05 to 1.45, p = 0.03), and ≥20mm3 infarct size (OR, 1.74, 95% CI: 1.14 to 3.13, p = 0.02) were independent factors for having depression in patents with psychological symptoms. The family dysfunction (OR, 2.32, 95% CI: 1.51 to 2.80, p < 0.01) and hypertension (OR, 2.41, 95% CI: 1.54 to 3.46, p = 0.03) were independent factors for emerging somatization and anxiety in patients with psychological symptoms, respectively. Conclusions: At three months after their stroke, young ischemic stroke patients had psychological problems and risk factors for developing them.

10.
Bioorg Med Chem Lett ; : 127854, 2021 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-33631370

RESUMO

p300 and CREB-binding protein (CBP) are essential for a multitude of cellular processes. Dysregulation of p300/CBP histone acetyltransferase activity is linked to a broad spectrum of human diseases including cancers. A novel drug-like spirohydantoin (21) has been discovered as a selective orally bioavailable inhibitor of p300/CBP histone acetyltransferase. Lead compound 21 is more potent than the first-in-class lead A-485 in both enzymatic and cellular assays and lacks the off-target inhibition of dopamine and serotonin transporters, that was observed with A-485.

11.
J Med Chem ; 64(4): 1844-1855, 2021 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-33570950

RESUMO

The acetylcholinesterase (AChE) inhibitors remain key therapeutic drugs for the treatment of Alzheimer's disease (AD). However, the low-safety window limits their maximum therapeutic benefits. Here, a novel kinetics-driven drug design strategy was employed to discover new-generation AChE inhibitors that possess a longer drug-target residence time and exhibit a larger safety window. After detailed investigations, compound 12 was identified as a highly potent, highly selective, orally bioavailable, and brain preferentially distributed AChE inhibitor. Moreover, it significantly ameliorated cognitive impairments in different mouse models with a lower effective dose than donepezil. The X-ray structure of the cocrystal complex provided a precise binding mode between 12 and AChE. Besides, the data from the phase I trials demonstrated that 12 had good safety, tolerance, and pharmacokinetic profiles at all preset doses in healthy volunteers, providing a solid basis for its further investigation in phase II trials for the treatment of AD.

12.
Pain Ther ; 2021 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-33629263

RESUMO

INTRODUCTION: Adding adjuvants to local wound infiltration (LWI) provides long analgesic duration with fewer adverse effects. We aimed to compare the clinical effects of nalbuphine and ketorolac as an adjuvant to LWI in patients undergoing open colorectal cancer surgery. METHOD: A total of 126 ASA I-III patients aged ≥ 18 years who were scheduled for open colorectal cancer surgery were included. Patients were randomly assigned to receive LWI using 10 mL 0.75% ropivacaine, with 20 mL normal saline (group R), 10 mg nalbuphine in 1 mL (group RN), or 25 mg ketorolac in 0.8 mL (group RK). Analgesia duration was the primary outcome. The total 48-h postoperative morphine-equivalent consumption and additional rescue analgesia rates were recorded as key secondary outcomes. RESULTS: Among 126 patients randomized, 124 completed the trial. The duration until the first press of the analgesia pump was significantly shorter in group R (median: 320.0 min) compared with group RN (median: 829.5 min) and group RK (median: 820.0 min) (P < 0.001). The median difference in morphine consumption was 113.0 mg for group R vs. group RN (P < 0.001), and 115.5 mg for group R vs. group RK (P < 0.001). The proportion of patients using additional morphine within the first day after surgery in group R showed a higher relative risk (RR) compared with group RN (RR, 3.89; P = 0.001) and group RK (RR, 3.17; P = 0.001). There were no apparent differences between the RN and RK groups in any outcomes, whether in adjusted or unadjusted analysis. CONCLUSIONS: Among patients undergoing open colorectal cancer surgery, both nalbuphine and ketorolac infiltration achieved equally prolonged duration of analgesia and reduced morphine consumption compared with ropivacaine alone after surgery, suggesting that the equivalent analgesic dose of nalbuphine and ketorolac as local anesthetic adjuvants in LWI could have a similar analgesic effect. TRIAL REGISTRATION: ChiCTR1800019209.

13.
Medicine (Baltimore) ; 100(6): e24570, 2021 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-33578554

RESUMO

RATIONALE: Intravenous pyogenic granuloma (IVPG) is a special type of pyogenic granuloma, and its preoperative diagnosis is difficult. We report a rare case of IVPG that develops in the lumen of the internal jugular vein (IJV). Here, we analyze the imaging characteristics of present case and summarize the imaging characteristics of previous reported cases. PATIENT CONCERNS: A 44-year-old man who presented with a growth in the IJV without any symptoms. DIAGNOSES: A diagnosis of IVPG was made, based on the pathological examination after surgery. INTERVENTIONS: The patient underwent surgery to excise the vein segment containing the neoplasm. OUTCOMES: The patient did not present with any complications in the postoperative follow-up period. LESSONS: For clinician, IVPG's preoperative diagnosis is difficult. Although histopathology remains the gold standard for diagnosis, the combination of multiple types of imaging examinations is necessary to rule out the differential diagnoses of IVPG.


Assuntos
Granuloma Piogênico/diagnóstico por imagem , Veias Jugulares/diagnóstico por imagem , Doenças Vasculares/diagnóstico por imagem , Adulto , Granuloma Piogênico/patologia , Granuloma Piogênico/cirurgia , Humanos , Veias Jugulares/patologia , Veias Jugulares/cirurgia , Imagem por Ressonância Magnética , Masculino , Tomografia Computadorizada por Raios X , Ultrassonografia , Doenças Vasculares/patologia , Doenças Vasculares/cirurgia
14.
Med Phys ; 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33523479

RESUMO

BACKGROUND: This article reports the first x-ray phase sensitive breast tomosynthesis (PBT) system that is aimed for direct translation to clinical practice for the diagnosis of breast cancer. PURPOSE: To report the preclinical evaluation and comparison of the newly built PBT system with a conventional digital breast tomosynthesis (DBT) system. METHODS AND MATERIALS: The PBT system is developed based on a comprehensive inline phase contrast theoretical model. The system consists of a polyenergetic microfocus x-ray source and a flat panel detector mounted on an arm that is attached to a rotating gantry. It acquires 9 projections over a 15° angular span in a stop-and-shoot-manner. A dedicated phase retrieval algorithm is integrated with a filtered back-projection method that reconstructs tomographic slices. The American College of Radiology (ACR) accreditation phantom, a contrast detail phantom and mastectomy tissue samples were imaged at the same glandular dose levels by both the PBT and a standard of care DBT system for image quality characterizations and comparisons. RESULTS: The PBT imaging scores with the ACR phantom are in good to excellent range and meet the quality assurance criteria set by the Mammography Quality Standard Act. The contrast detail phantom image comparison and associated statistical analyses from two-alternative forced-choice reader studies confirm the improvement offered by the PBT system in terms of contrast resolution, spatial resolution, and conspicuity. The artifact spread function (ASF) analyses revealed a sizable lateral spread of metal artifacts in PBT slices as compared to DBT slices. Signal to noise ratio (SNR) values for various inserts of the ACR and CD phantoms further validated the superiority of the PBT system. Mastectomy sample images acquired by the PBT system showed a superior depiction of microcalcifications versus the DBT system. CONCLUSION: The PBT imaging technology can be clinically employed for improving the accuracy of breast cancer screening and diagnosis.

15.
J Cell Physiol ; 2021 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-33554336

RESUMO

Breast cancer, a common malignancy for women, preferentially metastasizes to bone and obesity elevates the chance of its progression. While mechanical loading can suppress obesity and tumor-driven osteolysis, its effect on bone-metastasized obese mice has not been investigated. Here, we hypothesized that mechanical loading can lessen obesity-associated bone degradation in tumor-invaded bone by regulating the fate of bone marrow-derived cells. In this study, the effects of mechanical loading in obese mice were evaluated through X-ray imaging, histology, cytology, and molecular analyses. Tumor inoculation to the tibia elevated body fat composition, osteolytic lesions, and tibia destruction, and these pathologic changes were stimulated by the high-fat diet (HFD). However, mechanical loading markedly reduced these changes. It suppressed osteoclastogenesis by downregulating receptor activator of nuclear factor Kappa-B ligand and cathepsin K and promoted osteogenesis, which was associated with the upregulation of OPG and downregulation of C/enhancer-binding protein alpha and proliferator-activated receptor gamma for adipogenic differentiation. Furthermore, it decreased the levels of tumorigenic genes such as Rac1, MMP9, and interleukin 1ß. In summary, this study demonstrates that although a HFD aggravates bone metastases associated with breast cancer, mechanical loading significantly protected tumor-invaded bone by regulating the fate of bone marrow-derived cells. The current study suggests that mechanical loading can provide a noninvasive, palliative option for alleviating breast cancer-associated bone metastasis, in particular for obese patients.

16.
Arch Gynecol Obstet ; 2021 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-33555431

RESUMO

OBJECTIVE: To observe the levels of leukemia inhibitory factor (LIF), interleukin-6 (IL-6) and vascular endothelial growth factor (VEGF) in blood, peritoneal fluid, ectopic endometrial tissue, and ectopic endometrial stromal cells of patients with endometriosis, and to compare expression of IL-6, LIF and VEGF expression between endometriotic and non-endometriotic patients underwent laparoscopic surgery. METHODS: Thirty-one patients who underwent laparoscopic surgery for endometriosis in our hospital from January 2018 to January 2020 were included in the observation group, and 32 patients who underwent laparoscopic surgery for uterine fibroids, ovarian serous cystadenoma, and ovarian teratomas, were included in the control group. The levels of LIF, IL-6 and VEGF in the blood and peritoneal fluid of the two groups of patients were detected. The levels of LIF, IL-6 and VEGF in ectopic endometrial tissue and self-paired eutopic endometrial tissue, ectopic endometrial stromal cells and self-paired eutopic endometrial stromal cells of patients in the observation group were detected. After treating the primary cultured ectopic endometrial stromal cells with LIF and IL-6 alone or in combination, the changes of VEGF mRNA of ectopic endometrial stromal cells and the VEGF levels in the supernatant were observed. RESULTS: The levels of LIF, IL-6 and VEGF in the blood and peritoneal fluid of the observation group were all higher than those of the control group (P < 0.05), and the levels of LIF, IL-6 and VEGF in the peritoneal fluid of the observation group were significantly higher than those in the blood (P < 0.05). In the observation group, the expression levels of LIF-mRNA and IL-6 mRNA in the ectopic endometrial tissue were higher than those in the self-paired eutopic endometrial tissues (P < 0.05), while the expression level of VEGF mRNA in the ectopic endometrial tissues was lower than that in the self-paired eutopic endometrial tissues (P < 0.05). Besides, the mRNA expression levels of LIF, IL-6 and VEGF in ectopic endometrial stromal cells of the observation group were all higher than those in the self-paired eutopic endometrial stromal cells (P < 0.05). After stimulating ectopic endometrial stromal cells with LIF, IL-6 and LIF + IL-6, respectively, the VEGF levels in the supernatant were all significantly higher than that in the blank control group (P < 0.05). CONCLUSION: The LIF, IL-6 and VEGF levels in blood and peritoneal fluid were increased in patients with endometriosis, and increased LIF and IL-6 in ectopic endometriosis stromal cells can play a synergistic role in increasing the VEGF levels, which may be involved in the occurrence and development of endometriosis.

17.
J Med Chem ; 64(3): 1362-1391, 2021 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-33523672

RESUMO

Histone deacetylases (HDACs) are essential for maintaining homeostasis by catalyzing histone deacetylation. Aberrant expression of HDACs is associated with various human diseases. Although HDAC inhibitors are used as effective chemotherapeutic agents in clinical practice, their applications remain limited due to associated side effects induced by weak isoform selectivity. HDAC6 displays unique structure and cellular localization as well as diverse substrates and exhibits a wider range of biological functions than other isoforms. HDAC6 inhibitors have been effectively used to treat cancers, neurodegenerative diseases, and autoimmune disorders without exerting significant toxic effects. Progress has been made in defining the crystal structures of HDAC6 catalytic domains which has influenced the structure-based drug design of HDAC6 inhibitors. This review summarizes recent literature on HDAC6 inhibitors with particular reference to structural specificity and functional diversity. It may provide up-to-date guidance for the development of HDAC6 inhibitors and perspectives for optimization of therapeutic applications.

19.
J Hazard Mater ; 412: 125246, 2021 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-33548776

RESUMO

Transformation of chloro-organic compounds by nFe(0) has been studied extensively, but limited study exists on the transformation and fate of nFe(0) during the dechlorination of chloro-organics even though such knowledge is important in predicting its surface chemistry, particularly, toxicity in the environment. In this study, the nFe(0) core became hollowed, collapsed and gradually corroded into poorly crystallized ferrihydrite (Fe5O3(OH)9) at the pristine reaction time, which later gave rise to lath-like lepidocrocite (γ-FeOOH), acicular goethite (α-FeOOH) and cubic magnetite (Fe3O4) by the end of the reaction time (120 min). Also, dechlorination of 2,4-DCP into 2-CP, 4-CP and phenol was achieved within 120 min. The rapid dechlorination of 2,4-DCP and transformation of nFe(0) could not be achieved significantly without doping Ni on nFe(0) and supporting on attapulgite. The schematic representation of the transformation and compositional evolution of nFe(0) in A-nFe/Ni was proposed. These findings are critical in understanding the compositional evolution and the fate of nFe(0) upon reaction with chloro-organics and can provide guidance for more efficient uses of the nFe(0) reactivity towards the target contaminants in groundwater remediation.

20.
Inorg Chem ; 2021 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-33560831

RESUMO

We report herein a series of Cp*Ir complexes containing a rigid 8-aminoquinolinesulfonamide moiety as highly efficient catalysts for the dehydrogenation of formic acid (FA). The complex [Cp*Ir(L)Cl] (HL = N-(quinolin-8-yl)benzenesulfonamide) displayed a high turnover frequency (TOF) of 2.97 × 104 h-1 and a good stability (>100 h) at 60 °C. Comparative studies of [Cp*Ir(L)Cl] with the rigid ligand and [Cp*Ir(L')Cl] (HL' = N-propylpypridine-2-sulfonamide) without the rigid aminoquinoline moiety demonstrated that the 8-aminoquinoline moiety could dramatically enhance the stability of the catalyst. The electron-donating ability of the N,N'-chelating ligand was tuned by functionalizing the phenyl group of the L ligand with OMe, Cl, and CF3 to have a systematical perturbation of the electronic structure of [Cp*Ir(L)Cl]. Experimental kinetic studies and density functional theory (DFT) calculations on this series of Cp*Ir complexes revealed that (i) the electron-donating groups enhance the hydrogen formation step while slowing down the ß-hydride elimination and (ii) the electron-withdrawing groups display the opposite effect on these reaction steps, which in turn leads to lower optimum pH for catalytic activity compared to the electron-donating groups.

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