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1.
Molecules ; 29(17)2024 Aug 28.
Article in English | MEDLINE | ID: mdl-39274925

ABSTRACT

Recent years have seen increasing interest in uranyl(VI) photocatalysis. In this study, uranyl complexes were successfully synthesized from ligands L1-L6 and UO2(NO3)2·6H2O under reflux conditions, yielding products 1-6 with yields ranging from 30% to 50%. The complexes were thoroughly characterized using NMR spectroscopy, single-crystal X-ray diffraction, and elemental analysis. The results indicate that complexes 1-5 possess a pentagonal bipyramidal geometry, whereas complex 6 exhibits an octahedral structure. The photocatalytic properties of these novel complexes for sp3 C-H bond functionalization were explored. The results demonstrate that complex 4 functions as an efficient photocatalyst for converting C-H bonds to C-C bonds via hydrogen atom transfer under blue light irradiation.

2.
Chemistry ; : e202402995, 2024 Sep 21.
Article in English | MEDLINE | ID: mdl-39305150

ABSTRACT

The synthesis of α-tertiary amino acids (ATAAs), which are pivotal components in natural metabolism and pharmaceutical innovation, continues to attract significant research interest. Despite substantial advancements, the pursuit of a facile, versatile, and resource-efficient methodology remains an area of active development. In this work, we introduce a visible light-triggered three-component reaction involving readily available nitrosoarenes, N-acyl pyrazoles, and allyl or (bromomethyl)benzenes under mild conditions. This approach enables the straightforward assembly of a wide array of ATAA derivatives (41 examples) in commendably high yields (up to 89%). Mechanistic investigations elucidate that the reaction proceeds through a dehydration condensation between nitrosoarenes and N-acyl pyrazoles to generate ketimine intermediates. This is followed by a light-driven halogen atom transfer (XAT) process and a radical addition, culminating in the formation of the desired products. The approach showcases excellent functional group compatibility and late-stage derivatization potential, offering new insights and avenues for the synthesis of ATAA analogs.

3.
Nano Lett ; 2024 Sep 19.
Article in English | MEDLINE | ID: mdl-39297547

ABSTRACT

Modern quantum device fabrication often requires precisely adding and removing materials in situ at nanoscales, which is challenging for high-quality correlated oxide devices. In this work, we present a novel nanofabrication method that remotely controls the interfacial metal-insulator transition at the LaAlO3/SrTiO3 interface by selectively removing an LaAlO3 overlayer using a diamond tip. Remarkably, we observe a large force window within which single atomic layer precision of control is achievable. Our results confirm the critical thickness and charge transfer mechanism through a layer-by-layer removal process at the interface. Additionally, high-quality nanodevices, including nanochannels and single electron transistors, are successfully fabricated using this method. This nonvolatile and high-precision nanofabrication method provides a promising oxide platform for quantum engineering by harnessing the rich electron correlations at the nanoscale.

4.
Food Chem ; 456: 139933, 2024 Oct 30.
Article in English | MEDLINE | ID: mdl-38852462

ABSTRACT

Neglected and underutilised plants such as Pseudocydonia sinensis (Chinese quince) have garnered global interest as invaluable sources of natural bioactive compounds. Herein, a wide-targeted metabolomics-based approach revealed 1199 concurrent metabolites, with further analysis of their fluctuations across with the five stages of fruit growth. The bioactive compounds in Chinese quince primarily comprised sugars and organic acids, flavonoids, and terpenoids. Moreover, 395 metabolites were identified as having medicinal properties and rutin was the most content of them. Transcriptome analysis further provided a molecular basis for the metabolic changes observed during fruit development. By thoroughly analysing metabolite and transcriptome data, we revealed changes in bioactive compounds and related genes throughout fruit development. This study has yielded valuable insights into the ripening process of Chinese quince fruit, presenting substantial implications for industrial applications, particularly in quality control.


Subject(s)
Fruit , Metabolomics , Fruit/growth & development , Fruit/chemistry , Fruit/metabolism , Fruit/genetics , Gene Expression Profiling , Transcriptome , Flavonoids/metabolism , Gene Expression Regulation, Plant , Plant Proteins/genetics , Plant Proteins/metabolism , Plant Extracts/metabolism , Plant Extracts/chemistry
5.
Genome Biol ; 25(1): 116, 2024 05 07.
Article in English | MEDLINE | ID: mdl-38715020

ABSTRACT

BACKGROUND: Structural variations (SVs) have significant impacts on complex phenotypes by rearranging large amounts of DNA sequence. RESULTS: We present a comprehensive SV catalog based on the whole-genome sequence of 1060 pigs (Sus scrofa) representing 101 breeds, covering 9.6% of the pig genome. This catalog includes 42,487 deletions, 37,913 mobile element insertions, 3308 duplications, 1664 inversions, and 45,184 break ends. Estimates of breed ancestry and hybridization using genotyped SVs align well with those from single nucleotide polymorphisms. Geographically stratified deletions are observed, along with known duplications of the KIT gene, responsible for white coat color in European pigs. Additionally, we identify a recent SINE element insertion in MYO5A transcripts of European pigs, potentially influencing alternative splicing patterns and coat color alterations. Furthermore, a Yorkshire-specific copy number gain within ABCG2 is found, impacting chromatin interactions and gene expression across multiple tissues over a stretch of genomic region of ~200 kb. Preliminary investigations into SV's impact on gene expression and traits using the Pig Genotype-Tissue Expression (PigGTEx) data reveal SV associations with regulatory variants and gene-trait pairs. For instance, a 51-bp deletion is linked to the lead eQTL of the lipid metabolism regulating gene FADS3, whose expression in embryo may affect loin muscle area, as revealed by our transcriptome-wide association studies. CONCLUSIONS: This SV catalog serves as a valuable resource for studying diversity, evolutionary history, and functional shaping of the pig genome by processes like domestication, trait-based breeding, and adaptive evolution.


Subject(s)
Genome , Genomic Structural Variation , Animals , Sus scrofa/genetics , Polymorphism, Single Nucleotide , Swine/genetics , Chromosome Mapping
6.
RSC Adv ; 14(6): 4230-4243, 2024 Jan 23.
Article in English | MEDLINE | ID: mdl-38292266

ABSTRACT

Polysilicon is widely used in the field of semiconductors and solar energy. Trichlorosilane feedstocks that are used to produce polysilicon in the mainstream production process contain PCl3 impurities that have adverse effects on the quality of the polysilicon. Traditional methods for dephosphorization cannot achieve the effect of complete removal, whereas oxidizing PCl3 to POCl3 in the presence of oxygen for removal via adsorption is a promising and appealing route for establishing a dephosphorization process; it has a high phosphorous removal rate due to the strong Lewis-base property of POCl3 in comparison with PCl3. In this work, we synthesized an active catalyst with an active interface between Au nanoparticles (NPs) and a manganese-oxide support (Mn3O4) by calcination of a corresponding composite, where Au NPs were embedded uniformly in a metal-organic framework (MOF). The catalyst shows a significantly active catalytic performance for trace PCl3 oxidation in an organic system that is an imitation of a trichlorosilane system, with a 99.13% yield of POCl3 in an 80 °C and 0.6 MPa reaction environment. The structure-performance-mechanism analysis shows that the possible reaction and catalytic mechanism is PCl3 oxidation by interface lattice oxygens, which bridge the Au NPs and the support, in a Mars van Krevelen (MvK) process; this process was promoted by the interaction between the Au NPs and Mn3O4 in terms of charge transfer and chemical potential changes. This work provides an effective way to dephosphorize trichlorosilane feedstocks in the polysilicon industry and gives guidance for constructing an efficient catalyst via the study of the structure and mechanism.

7.
Nat Genet ; 56(1): 112-123, 2024 Jan.
Article in English | MEDLINE | ID: mdl-38177344

ABSTRACT

The Farm Animal Genotype-Tissue Expression (FarmGTEx) project has been established to develop a public resource of genetic regulatory variants in livestock, which is essential for linking genetic polymorphisms to variation in phenotypes, helping fundamental biological discovery and exploitation in animal breeding and human biomedicine. Here we show results from the pilot phase of PigGTEx by processing 5,457 RNA-sequencing and 1,602 whole-genome sequencing samples passing quality control from pigs. We build a pig genotype imputation panel and associate millions of genetic variants with five types of transcriptomic phenotypes in 34 tissues. We evaluate tissue specificity of regulatory effects and elucidate molecular mechanisms of their action using multi-omics data. Leveraging this resource, we decipher regulatory mechanisms underlying 207 pig complex phenotypes and demonstrate the similarity of pigs to humans in gene expression and the genetic regulation behind complex phenotypes, supporting the importance of pigs as a human biomedical model.


Subject(s)
Gene Expression Profiling , Gene Expression Regulation , Swine/genetics , Animals , Humans , Genotype , Phenotype , Sequence Analysis, RNA
8.
Pulm Pharmacol Ther ; 84: 102285, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38191069

ABSTRACT

Pulmonary fibrosis is a complex disease that can occur in a variety of clinical settings. The Zinc Finger and BTB Domain Containing 16 (Zbtb16) is a transcription factor and has not been studied in pulmonary fibrosis. Lung tissues from rats which were treated with bleomycin and Tanshinone IIA (Tan IIA) were collected for mRNA sequencing. Zbtb16, a differentially expressed gene, was screened. Using adeno-associated virus to knock down Zbtb16 in rats, it was found that the lung index and the content of hydroxyproline in lung tissue were decreased. HE and Masson staining revealed that pathological symptoms of lung histopathology were relieved after Zbtb16 knockdown. Protein expressions of α-SMA, Collagen I and Fibronectin were significantly decreased after Zbtb16 knockdown in vivo and in vitro. Meanwhile, the protein content of TGF-ß1 and the phosphorylation of Smad2/3 were inhibited by Zbtb16 knockdown. Conversely, under the treatment of Tan IIA and TGF-ß1, overexpression of Zbtb16 improved cell viability, increased the expression of fibrosis-related proteins, and promoted the phosphorylation of Smad 2/3. All above demonstrates that Zbtb16 inhibition ameliorates pulmonary fibrosis and suppresses the TGF-ß/Smad pathway. Furthermore, Zbtb16 mediates the inhibitory process of Tan IIA on pulmonary fibrosis. This study provides a novel candidate therapeutic target for pulmonary fibrosis.


Subject(s)
Abietanes , Pulmonary Fibrosis , Animals , Rats , Bleomycin/toxicity , Pulmonary Fibrosis/chemically induced , Pulmonary Fibrosis/drug therapy , Pulmonary Fibrosis/metabolism , Rats, Sprague-Dawley , Signal Transduction , Transforming Growth Factor beta1/metabolism
9.
Mol Hortic ; 3(1): 25, 2023 Nov 22.
Article in English | MEDLINE | ID: mdl-37990285

ABSTRACT

Drought stress has been demonstrated to enhance the biosynthesis of anthocyanins in the leaves, resulting in an increased aesthetic appeal. However, the molecular mechanisms underlying drought-induced anthocyanin biosynthesis in Chaenomeles speciosa remain unclear. In this study, the metabolites of C. speciosa leaves were analyzed, and it was found that the content of cyanidin-3-O-rutinoside increased significantly under drought stress. The differentially expressed genes CsMYB123 and CsbHLH111 were isolated by transcriptomics data analysis and gene cloning, and gene overexpression and VIGS experiments verified that both play important roles in anthocyanin biosynthesis. Subsequently, Y1H and Dual-luciferase reporter assay showed that CsMYB123 binds to the promoters of anthocyanin biosynthesis-related structural genes (such as CsCHI, CsF3H, and CsANS), while CsbHLH111 was shown to bind to the promoter of CsCHI, positively regulating its activity. Furthermore, BIFC and Y2H assays unveiled potential protein-protein interactions between CsMYB123 and CsbHLH111 at the cell nucleus. Collectively, these results shed light on the critical roles played by CsMYB123 and CsbHLH111 in anthocyanin biosynthesis, thus providing a valuable insight into understanding the molecular mechanisms of how the MYB and bHLH genes regulate anthocyanin biosynthesis in the process of leaf coloration in C. speciosa.

10.
Behav Brain Res ; 452: 114548, 2023 08 24.
Article in English | MEDLINE | ID: mdl-37355234

ABSTRACT

Maternal separation (MS) is a type of early-life stress that has been linked to neuropsychiatric disorders, especially depression. Increasing evidence indicates that the adenosine triphosphate (ATP) level in the prefrontal cortex (PFC) is involved in the pathophysiology of depression. To investigate the potential relationship between ATP in PFC and antidepressant effects of electroacupuncture (EA) treatment, we assessed genes involved in ATP biosynthesis as well as the extracellular ATP levels in a rat model exposed to neonatal MS. Our results demonstrated that reduced expression of ABCG2 (an ATP-binding cassette protein) and ATP levels in the PFC of depressive-like rats exposed to MS can be attenuated by EA stimulus at the Baihui (GV20) and Yintang (GV29) acupoints. Moreover, the antidepressant effect of EA treatment was blocked by administration of suramin, a broad purinergic P2 receptor antagonist. Together, these results suggested that electroacupuncture may be able to modulate extracellular ATP levels in the PFC of depressive-like MS rats, potentially contributing to its antidepressant effects.


Subject(s)
Electroacupuncture , Rats , Animals , Rats, Sprague-Dawley , Electroacupuncture/methods , Maternal Deprivation , Prefrontal Cortex , Antidepressive Agents/pharmacology
11.
BMC Pediatr ; 23(1): 233, 2023 05 12.
Article in English | MEDLINE | ID: mdl-37173706

ABSTRACT

BACKGROUND: The hypereosinophilic syndrome (HES) is a group of rare blood disorders characterized by persistent eosinophilia and damage to multiple organs. HES can be either primary, secondary or idiopathic. Secondary HES are commonly caused by parasitic infections, allergic reactions or cancer. We described a pediatric case of HES associated with liver damage and multiple thrombi. A 12-year-old boy with eosinophilia was complicated with severe thrombocytopenia, liver damage, portal vein, splenic vein, and superior mesenteric vein thromboses. The thrombi recanalized after treatment with methylprednisolone succinate and low molecular weight heparin. No side effects appeared after 1-month. CONCLUSIONS: Corticosteroids should be used at an early stage of HES to prevent further damage to vital organs. Anticoagulants should be recommended only in cases with thrombosis which should be actively screened as a part of evaluation of end organ damage.


Subject(s)
Hypereosinophilic Syndrome , Liver Diseases , Thrombosis , Male , Humans , Child , Portal Vein/diagnostic imaging , Splenic Vein/diagnostic imaging , Mesenteric Veins/diagnostic imaging , Thrombosis/etiology , Hypereosinophilic Syndrome/complications , Hypereosinophilic Syndrome/diagnosis , Hypereosinophilic Syndrome/drug therapy
12.
Physiol Plant ; 175(1): e13859, 2023 Jan.
Article in English | MEDLINE | ID: mdl-36688571

ABSTRACT

Chaenomeles speciosa is a plant with high ornamental value, and the color of its petals deepens obviously under drought stress. To understand the mechanism of drought-induced reddening of C. speciosa petal color, the metabolites and transcriptomics of petals from 4% PEG-8000-treated and control cuttings were analyzed. In this study, the analysis of metabolites revealed the accumulation of anthocyanins in petals of PEG-treated cuttings, indicating anthocyanins might be the reason for the deepening of petal color. By using transcriptomics, we identified CsMYB6 as an overexpressed transcription factor in PEG-treated samples. Transient overexpression and suppression of CsMYB6 revealed that it is a key transcription factor for anthocyanin synthesis. We identified genes related to anthocyanin biosynthesis and constructed a network of drought- and anthocyanin-related genes (such as CsMYB6, CsbHLH111, CsANS, CsDFR, and CsUFGT). Further experiments indicated that CsMYB6 directly interacted with CsbHLH111, and this interaction increased the binding ability of CsMYB6 to the promoter regions of three structural genes of anthocyanin biosynthesis: CsANS, CsDFR, and CsUFGT. Our findings provide a molecular basis and new insight into drought-induced anthocyanin biosynthesis in C. speciosa.


Subject(s)
Anthocyanins , Rosaceae , Anthocyanins/metabolism , Droughts , Transcription Factors/metabolism , Gene Expression Profiling , Rosaceae/genetics , Rosaceae/metabolism , Gene Expression Regulation, Plant , Plant Proteins/metabolism , Flowers/genetics
13.
World J Clin Cases ; 10(36): 13443-13450, 2022 Dec 26.
Article in English | MEDLINE | ID: mdl-36683631

ABSTRACT

BACKGROUND: Congenital nephrogenic diabetes insipidus (CNDI) is a rare hereditary disorder. It is associated with mutations in the arginine vasopressin receptor 2 (AVPR2) gene and aquaporin 2 (AQP2) gene, and approximately 270 different mutation sites have been reported for AVPR2. Therefore, new mutations and new manifestations are crucial to complement the clinical deficiencies in the diagnosis of this disease. We report a case of a novel AVPR2 gene mutation locus and a new clinical mani-festation. CASE SUMMARY: We describe the case of a 48-d-old boy who presented with recurrent fever and diarrhea 5 d after birth. Laboratory tests showed electrolyte disturbances and low urine specific gravity, and imaging tests showed no abnormalities. Genetic testing revealed a novel X-linked recessive missense mutation, c.283 (exon 2) C>T (p.P95S). This mutation results in the substitution of a proline residue with a serine residue in the AVPR2 protein sequence. The diagnosis of CNDI was confirmed based on the AVPR2 gene mutation. The treatment strategy for this patient was divided into two stages, including physical cooling supplemented with appropriate amounts of water in the early stage and oral hydrochlorothia-zide (1-2 mg/kg) after a clear diagnosis. After follow-up of one and a half years, the patient gradually improved. CONCLUSION: AVPR2 gene mutations in new loci and new clinical symptoms help clinicians understand this disease and shorten the diagnosis cycle.

14.
Chem Rec ; 22(2): e202100218, 2022 Feb.
Article in English | MEDLINE | ID: mdl-34618405

ABSTRACT

The formation of intramolecular C-N bond represents a powerful strategy in organic transformation as the great importance of N-heterocycles in the fields of natural products and bioactive molecules. This personal account describes the synthesis of cyclic phosphinamidation, benzosultam, benzosulfoximine, phenanthridine and their halogenated compounds through transition-metal-free intramolecular oxidative C-N bond formation. Mechanism study reveals that N-X bond is initially formed under the effect of hypervalent halogen, which is very unstable and easily undergoes thermal or light homolytic cleavage to generate nitrogen radical. Then the nitrogen radical is trapped by the arene to give aryl radical. Rearomatization of aryl radical under the oxidant to provide corresponding N-heterocycle. Under suitable conditions, the N-heterocycles can be further transformed to halogenated N-heterocycles.


Subject(s)
Transition Elements , Metals , Oxidation-Reduction
15.
BMC Gastroenterol ; 21(1): 416, 2021 Nov 01.
Article in English | MEDLINE | ID: mdl-34724892

ABSTRACT

BACKGROUND: MKI67 plays a vital role in the tumour microenvironment (TME) and congenital immunity. The present work focuses on exploring the prognosis prediction performance of MKI67 and its associations with T cell activity and immune infiltration within numerous cancers, especially hepatocellular liver carcinoma (LIHC). METHODS: Oncomine, GEPIA2, and HPA were adopted to analyse MKI67 levels in different types of cancers. The prognostic prediction performance of MKI67 was evaluated through the TCGA portal, GEPIA2, LOGpc, and Kaplan-Meier Plotter databases. The associations of MKI67 with related gene marker sets and immune infiltration were inspected through TISIDB, GEPIA2, and TIMER. We chose MKI67 to analyse biological processes (BPs) and KEGG pathways related to the coexpressed genes. Furthermore, the gene-miRNA interaction network for MKI67 in liver cancer was also examined based on the miRWalk database. RESULTS: MKI67 expression decreased in many cancers related to the dismal prognostic outcome of LIHC. We found that MKI67 significantly affected the prognosis of LIHC in terms of histology and grade. Increased MKI67 levels were directly proportional to the increased immune infiltration degrees of numerous immune cells and functional T cells, such as exhausted T cells. In addition, several critical genes related to exhausted T cells, including TIM-3, TIGIT, PD-1, LAG3, and CXCL13, were strongly related to MKI67. Further analyses showed that MKI67 was associated with adaptive immunity, cell adhesion molecules (CAMs), and chemokine/immune response signal transduction pathways. CONCLUSION: MKI67 acts as a prognostic prediction biomarker in several cancers, particularly LIHC. Upregulation of MKI67 elevates the degree of immune infiltration of many immune cell subtypes, including functional T cells, CD4+ T cells, and CD8+ T cells. Furthermore, MKI67 shows a close correlation with T cell exhaustion, which plays a vital role in promoting T cell exhaustion within LIHC. Detection of the MKI67 level contributes to prognosis prediction and MKI67 modulation within exhausted T cells, thus providing a new method to optimize the efficacy of anti-LIHC immunotherapy.


Subject(s)
Carcinoma, Hepatocellular , Liver Neoplasms , Biomarkers, Tumor/genetics , CD8-Positive T-Lymphocytes , Humans , Prognosis , Tumor Microenvironment
16.
Medicine (Baltimore) ; 99(22): e20121, 2020 May 29.
Article in English | MEDLINE | ID: mdl-32481378

ABSTRACT

INTRODUCTION: The aim of this study was to evaluate the efficacy and safety of azithromycin (AZI) combined with glucocorticoid (GC) in the treatment of children with refractory Mycoplasma pneumoniae. METHODS: Computer search for PubMed, EMbase, Cochrane Library, China Biomedical Literature Database (CBMdisc), China Knowledge Network (CNKI), Wanfang, VIP (VIP), and a randomized controlled trial (RCT) of AZI combined with GC in the treatment of children with refractory Mycoplasma pneumoniae pneumonia test (RCT), the search time limit is built until March 20, 2019. Two researchers independently performed literature screening, data extraction, and literature risk bias, and meta-analysis was performed using RevMan 5.3 software. RESULTS: A total of 12 RCTs were included, including 1130 patients. Meta-analysis showed that AZI combined with GC therapy significantly improved the total effective rate of the disease compared with the conventional treatment group (odds ratio [OR] = 6.37; 95% confidence interval [CI] 4.03, 10.07; P < .00001; I = 0%), effectively shortened the antipyretic time (SMD = -2.29; 95% CI -2.70, -1.88; P < .0001); promoted lung inflammation absorption (SMD = -1.89; 95% CI -2.38, -1.40; P < .0001), reduced cough time (SMD = -2.39; 95% CI -2.80, -1.99; P < .0001); shortened hospital stay (SMD = -2.19; 95% CI -3.21, -1.17; P < .0001); improved imaging findings (OR = 5.38; 95% CI 1.09, 26.51, P = .04); reduced inflammation index (SMD = -3.15; 95% CI -4.93, -1.36; P = .004); improved immune function (SMD = 1.29; 95% CI -0.02, 2.60; P < .0001); had no significant adverse reactions (OR = 1.18; 95% CI 0.71, 1.98; P = .53). CONCLUSIONS: According to the current limited research evidence, the addition of GCs to the conventional treatment of refractory Mycoplasma pneumoniae in children can improve the clinical efficacy to a certain extent, and the safety is better. However, due to the quality and quantity of the included literature, the conclusions of this study need to be confirmed by more high-quality studies.


Subject(s)
Anti-Bacterial Agents/therapeutic use , Azithromycin/therapeutic use , Glucocorticoids/therapeutic use , Mycoplasma pneumoniae , Pneumonia, Mycoplasma/drug therapy , Anti-Bacterial Agents/adverse effects , Azithromycin/adverse effects , Child , Cough/drug therapy , Cough/microbiology , Drug Therapy, Combination , Fever/drug therapy , Fever/microbiology , Glucocorticoids/adverse effects , Humans , Length of Stay , Pneumonia, Mycoplasma/complications , Pneumonia, Mycoplasma/diagnostic imaging
17.
Front Chem ; 7: 768, 2019.
Article in English | MEDLINE | ID: mdl-31803716

ABSTRACT

Carbazole based fluorophores 9-butyl-3,6-bis-(phenylethynyl)-9H-carbazole (1) and 9-butyl-3,6-bis-(2-phenyl-o-carborane)-9H-carbazole (2) were synthesized via Sonogashira type cross-coupling reaction and followed by insertion with decaborane. Compound 1 exhibited far more intense fluorescence than 2 in THF solution, while in solid state 2 exerted stronger fluorescence than 1. The fluorescence quenching behavior of 2 in THF solution could be attributed to the intramolecular charge transfer of donor-acceptor system in 2, which was confirmed by electrochemical experiments and DFT calculations. The fluorescence enhancement of 2 in solid state can be ascribed to aggregational induced packing which was evidenced by crystallographic study. In addition, compound 2 showed typical aggregation induced emission (AIE) behavior.

18.
Dalton Trans ; 48(35): 13242-13247, 2019 Sep 21.
Article in English | MEDLINE | ID: mdl-31414094

ABSTRACT

Five examples of bis(pyrazolyl)borate Ni(ii) complexes 2-5, exhibiting C-HNi interactions, were readily prepared from the reactions of K[BBN(3-R1-4-R2-pz)2] with Ni(ii) precursors (Ni(acac)2 or NiCl2(PPh3)2) in dichloromethane or toluene. When R1 = R2 = H, complex 2a with square-planar geometry around the Ni centre and showing an unusual C-HNi anagostic interaction was obtained. In contrast, when R1 = Me, R2 = H or R1 = Me, R2 = Br, tetrahedral complexes 3 or 4 were formed preferentially with strong C-HNi agostic interactions, respectively. Additionally, some differences in the formation and transformation of 3 and 4 were also found including a 1,2-borotropic shift during the formation of 3 and a further geometrical transformation from tetrahedral 3 to square-planar 2b by the second 1,2-borotropic shift under continuous heating; in contrast, no ligand change and further conversion were found in 4. When the more hindered 3-iPr-substituted ligand 1d was introduced in the reaction, the hydrolysis and cleavage of one B-N bond in the ligand occurred, leading to the singly hydroxo-bridged complex 5. The experimental and theoretical results indicate that the preference to form a thermodynamically stable complex and then balancing with orbital energy should be the intrinsic reason for the reaction selectivity.

19.
Angew Chem Int Ed Engl ; 58(11): 3268-3278, 2019 Mar 11.
Article in English | MEDLINE | ID: mdl-30353633

ABSTRACT

A number of recently discovered nucleophilic boron compounds, such as boryl anions and borylenes, are breaking the rules regarding boron and boron-containing compounds and their reputation as Lewis acids/electrophiles. In a similar fashion, the B-H bonding pair electrons in boranes also show nucleophilicity which is ascribed to the lower electronegativity of boron relative to that of hydrogen. However, this nucleophilicity of the B-H bond has received far less attention. Explorations of the nucleophilicity of the B-H bonding pair electrons have led to the formation of B-H-B bonded units and B-H⋅⋅⋅H-Y dihydrogen bonds, based on which new chemistry has been uncovered, including the elucidation of the mechanism of formation of aminodiborane (ADB), the diammoniate of diborane (DADB), and lithium or sodium salts of octahydrotriborates (B3 H8 - ), as well as the development of more convenient and straightforward synthetic routes to these reagents. Moreover, the recognition of the nucleophilic properties of the B-H bonding pair electrons will also help to more deeply understand the different mechanisms operating in hydroboration reactions.

20.
J Org Chem ; 83(24): 14969-14977, 2018 Dec 21.
Article in English | MEDLINE | ID: mdl-30353732

ABSTRACT

In contrast to the conventional strategy of modifying the reactivities and selectivities of the transition metal and organocatalysts by varying the steric and electronic properties of organic substituent groups, we hereby demonstrate a novel approach that the sigma (σ) nucleophilicity of the imine arm can be significantly enhanced in a pseudodearomatized PN3P* pincer ligand platform to reach unprecedented N-heterocyclic carbene-like reactivity. Accordingly, the imine arm of the PN3P*Ni-H pincer complex efficiently catalyzes the hydrosilylation of aldehydes, cycloaddition of carbon dioxide (CO2) to epoxides, and serves as a ligand in the Ru-catalyzed dehydrogenative acylation of amines with alcohols.

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