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1.
Chemosphere ; 244: 125465, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32050324

RESUMO

Criteria continuous concentrations (CCCs) are the scientific basis for making sound environmental management decisions and assessing surface water quality. Transition metals are a group of elements, similar in physicochemical properties perpendicularly and horizontally across the Periodic Table, some of which are widely distributed in aquatic environments and can cause adverse effects on aquatic life and human health. Currently internationally recommended CCCs are available for only seven transition metals. It is challenging to derive CCCs for transition metals based on scarce empirical information. The present study found significant relationships between the suggested CCCs of transition metals and their nine physicochemical properties and an empirical model was developed to satisfactorily predict the CCCs of 56 transition metals by use of the most relevant parameter, r, for protecting aquatic ecosystems. Predicted values were largely consistent with the CCCs and CMCs predicted previously and over 80% predicted CMCs of transition metals are greater than or equal to their CCCs. The present study shows methodological advantages in obtaining CCCs, and provides reliable reference values for setting chronic WQC and assessing risk of transition metals.


Assuntos
Elementos de Transição/química , Qualidade da Água/normas , Animais , Fenômenos Químicos , Ecossistema , Humanos , Metais/análise , Metais/química , Medição de Risco , Poluentes Químicos da Água/análise
2.
Chem Soc Rev ; 49(4): 1090-1108, 2020 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-32016270

RESUMO

Inorganic phosphate has numerous biomedical functions. Regulated primarily by the kidneys, phosphate reaches abnormally high blood levels in patients with advanced renal diseases. Since phosphate cannot be efficiently removed by dialysis, the resulting hyperphosphatemia leads to increased mortality. Phosphate is also an important component of the environmental chemistry of surface water. Although required to secure our food supply, inorganic phosphate is also linked to eutrophication and the spread of algal blooms with an increasing economic and environmental burden. Key to resolving both of these issues is the development of accurate probes and molecular receptors for inorganic phosphate. Yet, quantifying phosphate in complex aqueous media remains challenging, as is the development of supramolecular receptors that have adequate sensitivity and selectivity for use in either blood or surface waters. Metal-based receptors are particularly well-suited for these applications as they can overcome the high hydration enthalpy of phosphate that limits the effectiveness of many organic receptors in water. Three different strategies are most commonly employed with inorganic receptors for anions: metal extrusion assays, responsive molecular receptors, and indicator displacement assays. In this review, the requirements for molecular receptors and probes for environmental applications are outlined. The different strategies deployed to recognize and sense phosphate with metal ions will be detailed, and their advantages and shortfalls will be delineated with key examples from the literature.


Assuntos
Metais/química , Fosfatos/química , Quelantes/química , Complexos de Coordenação/química , Elementos da Série dos Lantanídeos/química , Metais/metabolismo , Fosfatos/metabolismo , Elementos de Transição/química , Água/química
3.
Top Curr Chem (Cham) ; 378(2): 23, 2020 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-32064557

RESUMO

Biaryl scaffolds are prevalent in natural products and drug molecules, and biaryl-containing compounds have been shown to exhibit diverse and interesting biological activities. To date, numerous synthetic methods, particularly direct C-H bond activation, have been developed for the construction of such scaffolds, due to their interesting structural features and biological profiles. We highlight herein recent advances in the construction of biologically important biaryl fragments through direct C-H bond activation and also demonstrate the application of direct C-H arylation in the total synthesis of biaryl-containing natural products and drug molecules. Selected biaryl-containing compounds.


Assuntos
Produtos Biológicos/química , Preparações Farmacêuticas/química , Carbono/química , Catálise , Hidrogênio/química , Elementos de Transição/química
4.
Top Curr Chem (Cham) ; 378(1): 16, 2020 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-31942682

RESUMO

The cooperation between two orthogonal catalytic events during the formation of carbon-carbon and carbon-heteroatom bonds has emerged as an effective strategy for enantioselective chemical synthesis. In recent years, a number of pioneering investigations have described useful chemical synthesis methods whereby the reactivity or nucleophile-electrophile combinations can be fine-tuned or extended far beyond the effect and influence of a single catalyst. The recognition of this has had profound implications for the development cooperative catalysis as a field and has provided a foundation for the development of broadly useful chemical synthesis methods. This chapter focuses on the combination of tertiary amine Lewis base and transition metal catalysts, which the authors hope will simulate further developments and advances.


Assuntos
Compostos de Amônio/química , Bases de Lewis/química , Metais/química , Carbono/química , Catálise , Técnicas de Química Sintética/métodos , Estereoisomerismo , Elementos de Transição/química
5.
Chemistry ; 26(19): 4350-4377, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31910294

RESUMO

After briefly reviewing the applications of the coordination ability indices proposed earlier for anions and solvents toward transition metals and lanthanides, a new analysis of crystal structures is applied now to a much larger number of coordinating species: anions (including those that are present in ionic solvents), solvents, amino acids, gases, and a sample of neutral ligands. The coordinating ability towards s-block elements is now also considered. The effect of several factors on the coordinating ability will be discussed: (a) the charge of an anion, (b) the chelating nature of anions and solvents, (c) the degree of protonation of oxo-anions, carboxylates and amino carboxylates, and (d) the substitution of hydrogen atoms by methyl groups in NH3 , ethylenediamine, benzene, ethylene, pyridine and aldehydes. Hit parades of solvents and anions most commonly used in the areas of transition metal, s-block and lanthanide chemistry are deduced from the statistics of their presence in crystal structures.


Assuntos
Aminoácidos/química , Ânions/química , Elementos da Série dos Lantanídeos/química , Solventes/química , Elementos de Transição/química , Gases , Hidrogênio , Ligantes
6.
Chemistry ; 26(9): 1922-1927, 2020 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-31738451

RESUMO

The synthesis of a diverse range of heterobiaryls has been achieved by a transition-metal-free sp2 -sp2 cross-coupling strategy using lithiated heterocycle, aryl or heteroaryl boronic ester and an electrophilic halogen source. The construction of heterobiaryls was carried out through electrophilic activation of the aryl-heteroaryl boronate complex, which triggered 1,2-migration from boron to the carbon atom. Subsequent oxidation of the intermediate boronic ester afforded heterobiaryls in good yield. A comprehensive 11 B NMR study has been conducted to support the mechanism. The cross coupling between two nucleophilic cross coupling partners without transition metals reveals a reliable manifold to procure heterobiaryls in good yields. Various heterocycles like furan, thiophene, benzofuran, benzothiophene, and indole are well tolerated. Finally, we have successfully demonstrated the gram scale synthesis of the intermediates for an anticancer drug and OLED material using our methodology.


Assuntos
Ácidos Borônicos/química , Compostos Heterocíclicos/química , Catálise , Compostos Heterocíclicos/síntese química , Paládio/química , Teoria Quântica , Elementos de Transição/química
7.
Chemosphere ; 245: 125678, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31875574

RESUMO

The search for a suitable heterogeneous catalyst in peroxymonosulfate (PMS) activation holds tremendous promise for the degradation of organic pollutants. Two-dimensional (2D) transition metal dichalcogenides such as WS2 exhibit broad applications in heterogeneous catalysis, and we first extended its application in PMS activation in this work. It was found that WS2 could efficiently activate PMS resulting in the degradation of diclofenac (DCF). The results show that the PMS offers direct oxidation, and WS2 could initiate PMS to produce singlet oxygen (1O2) and superoxide radical (·O2-). This resulted in the improved removal of DCF in the WS2/PMS system. Furthermore, the degradation pathway of DCF was proposed according to the detected intermediates/products and density functional theory (DFT) calculation. Degradation intermediates and the evaluation of product toxicity indicated that the developed WS2/PMS system was a safe and detoxifying process while also offering efficient DCF removal. This study offers more insight into the development of suitable materials for the activation of PMS and gives clear direction for the degradation of DCF and its toxic intermediates.


Assuntos
Diclofenaco/isolamento & purificação , Nanoestruturas/química , Peróxidos/farmacologia , Compostos de Tungstênio/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Catálise , Diclofenaco/química , Oxirredução , Peróxidos/química , Oxigênio Singlete/química , Elementos de Transição/química , Elementos de Transição/farmacologia , Compostos de Tungstênio/farmacologia , Poluentes Químicos da Água/química
8.
Appl Opt ; 58(34): 9411-9420, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31873539

RESUMO

A novel surface plasmon resonance (SPR) biosensor based on Ag-Au bimetallic films with a hybrid structure of blue phosphorene (BlueP)/transition metal dichalcogenides (TMDCs) and graphene is presented. In order to improve the sensitivity, the thickness of silver and gold films is optimized to achieve minimum reflectivity and an adequate level of sensitivity; further, sensitivity for the monolayer BlueP/MoS2 and graphene structure is enhanced by 19.73%, with respect to a traditional sensor. Besides, the effect of layers of different Blue/TMDCs heterostructures to the sensitivity of the SPR biosensor is investigated, and the highest sensitivity with 335.4°/RIU for the bilayer BlueP/WS2 is obtained. Furthermore, distributions of the electric field and the changes of resonance angle to the refractive index of the sensing medium and prism in the visible regime are illustrated at optimal configuration. In virtue of highly sensitive characteristics, the proposed sensor structure will be a much better option to be employed for further biological detection.


Assuntos
Técnicas Biossensoriais/instrumentação , Grafite/química , Nanoestruturas/química , Ressonância de Plasmônio de Superfície/instrumentação , Elementos de Transição/química , Biopolímeros , Ouro/química , Modelos Teóricos , Sensibilidade e Especificidade , Prata/química , Ressonância de Plasmônio de Superfície/métodos
9.
Molecules ; 24(21)2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31683557

RESUMO

Functionalized cyclic organic carbonates and carbamates are frequently used in a number of transition metal-catalyzed decarboxylative reactions for the construction of interesting molecules. These decarboxylative transformations have attracted more and more research attention in recent years mainly due to their advantages of less waste generation and versatile reactivities. On the basis of previous reviews on this hot topic, the present review will focus on the development of transition metal-catalyzed decarboxylative transformations of functionalized cyclic carbonates and carbamates in the last two years.


Assuntos
Carbamatos/química , Carbonatos/química , Metais/química , Elementos de Transição/química , Catálise , Ciclização , Descarboxilação
10.
Top Curr Chem (Cham) ; 377(6): 38, 2019 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-31732819

RESUMO

The concept of merging enamine activation catalysis with transition metal catalysis is an important strategy, which allows for selective chemical transformations not accessible without this combination. The amine catalyst activates the carbonyl compounds through the formation of a reactive nucleophilic enamine intermediate and, in parallel, the transition metal activates a wide range of functionalities such as allylic substrates through the formation of reactive electrophilic π-allyl-metal complex. Since the first report of this strategy in 2006, considerable effort has been devoted to the successful advancement of this technology. In this chapter, these findings are highlighted and discussed.


Assuntos
Aminas/química , Elementos de Transição/química , Alquilação , Alquinos/química , Catálise , Complexos de Coordenação/química , Ciclização , Cetonas/química , Estereoisomerismo
11.
Nature ; 574(7778): 390-393, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31597960

RESUMO

Transition-metal complexes are widely used in the physical and biological sciences. They have essential roles in catalysis, synthesis, materials science, photophysics and bioinorganic chemistry. Our understanding of transition-metal complexes originates from Alfred Werner's realization that their three-dimensional shape influences their properties and reactivity1, and the intrinsic link between shape and electronic structure is now firmly underpinned by molecular-orbital theory2-5. Despite more than a century of advances in this field, the geometries of transition-metal complexes remain limited to a few well-understood examples. The archetypal geometries of six-coordinate transition metals are octahedral and trigonal prismatic, and although deviations from ideal bond angles and bond lengths are frequent6, alternative parent geometries are extremely rare7. The hexagonal planar coordination environment is known, but it is restricted to condensed metallic phases8, the hexagonal pores of coordination polymers9, or clusters that contain more than one transition metal in close proximity10,11. Such a geometry had been considered12,13 for [Ni(PtBu)6]; however, an analysis of the molecular orbitals suggested that this complex is best described as a 16-electron species with a trigonal planar geometry14. Here we report the isolation and structural characterization of a simple coordination complex in which six ligands form bonds with a central transition metal in a hexagonal planar arrangement. The structure contains a central palladium atom surrounded by three hydride and three magnesium-based ligands. This finding has the potential to introduce additional design principles for transition-metal complexes, with implications for several scientific fields.


Assuntos
Complexos de Coordenação/química , Metais/química , Complexos de Coordenação/isolamento & purificação , Ciência dos Materiais , Conformação Molecular , Elementos de Transição/química
12.
Dalton Trans ; 48(44): 16476-16492, 2019 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-31599913

RESUMO

Bispidones (3,7-diazabicyclo[3.3.1]nonan-9-one) are bicyclic analogues of the natural antiarrhythmic agent, spartein. They can straightforwardly be obtained from two successive Mannich reactions. Reduction of the ketone gives the corresponding bispidol. Substituted bispidones and bispidols offer a large playground by varying the substituents, the configuration of the carbon atoms in position 2 and 4 as well as the conformation of the bicycle. While chair-boat conformers display a strong affinity for κ-opioid receptors, chair-chair bispidines provide adaptable coordination spheres for transition metal and rare-earth ions. Because of their very rich coordination chemistry, substituted bispidines have emerged in various applications of coordination chemistry, such as catalysis, magnetism and medical imaging.


Assuntos
Compostos Bicíclicos Heterocíclicos com Pontes/química , Compostos Bicíclicos Heterocíclicos com Pontes/metabolismo , Complexos de Coordenação/química , Receptores Opioides kappa/química , Receptores Opioides kappa/metabolismo , Animais , Complexos de Coordenação/metabolismo , Humanos , Metais Terras Raras/química , Conformação Molecular , Radioterapia/métodos , Elementos de Transição/química
13.
Molecules ; 24(21)2019 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-31653123

RESUMO

The hydration of nitriles to amides in a water extract of pomelo peel ash (WEPPA) was realized with moderate to excellent yields without using external transition metals, bases or organic solvents. This reaction features a broad substrate scope, wide functional group tolerance, prominent chemoselectivity, and good reusability. Notably, a magnification experiment in this bio-based solvent at 100 mmol further demonstrated its practicability.


Assuntos
Amidas , Citrus/química , Frutas/química , Nitrilos , Elementos de Transição/química , Amidas/síntese química , Amidas/química , Nitrilos/síntese química , Nitrilos/química
14.
Top Curr Chem (Cham) ; 377(6): 30, 2019 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-31628623

RESUMO

Ionic liquids (ILs) are considered as highly useful materials for potential diverse uses such as greener and more convenient alternatives to volatile organic solvents, reagents, additives, ligands and co-solvents. Thermal stability, negligible vapor pressure and high polarity with ionic environments have possibly conferred some unique physico-chemical properties and a wider electrochemical window on ILs. More importantly, these properties are tuneable, depending on variations in alkyl chains and counter-anions. On the other hand, various transition-metal-catalyzed cross-coupling reactions constitute an important backbone of contemporary organic synthesis. A vast number of C-C and C-heteroatom cross-coupling reactions are reported in the presence of ILs, often showing better performance. The influence of IL on the action of a given catalyst or on the course of a reaction can be relatively complex, and is not understood well enough to be able to draw succinct conclusions. However, there are a few reports in the literature that help understand the role of actual and active catalytic species stabilized in an IL environment. Stabilization, which can be either helpful or detrimental to catalysis depends on specific circumstances. This review article is aimed primarily at summarizing the various applications of ILs during the past decade, focusing as far as possible on the task-specific properties of ILs in transition-metal-catalyzed C-C and C-heteroatom cross-coupling reactions. Several successful achievements and noteworthy progress in this field of research leads to the sensible conclusion that future prospects in this field of research are not only bright but promise new horizons.


Assuntos
Líquidos Iônicos/química , Catálise , Compostos Heterocíclicos/química , Ligantes , Metano/análogos & derivados , Metano/química , Solventes/química , Elementos de Transição/química
15.
Top Curr Chem (Cham) ; 377(6): 29, 2019 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-31605243

RESUMO

Sustainable and high performance energy devices such as solar cells, fuel cells, metal-air batteries, as well as alternative energy conversion and storage systems have been considered as promising technologies to meet the ever-growing demands for clean energy. Hydrogen evolution reaction (HER) is a crucial process for cost-effective hydrogen production; however, functional electrocatalysts are potentially desirable to expedite reaction kinetics and supply high energy density. Thus, the development of inexpensive and catalytically active electrocatalysts is one of the most significant and challenging issues in the field of electrochemical energy storage and conversion. Realizing that advanced nanomaterials could engender many advantageous chemical and physical properties over a wide scale, tremendous efforts have been devoted to the preparation of earth-abundant transition metals as electrocatalysts for HER in both acidic and alkaline environments because of their low processing costs, reasonable catalytic activities, and chemical stability. Among all transition metal-based catalysts, nickel compounds are the most widely investigated, and have exhibited pioneering performances in various electrochemical reactions. Heterostructured nickel phosphide (NixPy) based compounds were introduced as promising candidates of a new category, which often display chemical and electronic characteristics that are distinct from those of non-precious metals counterparts, hence providing an opportunity to construct new catalysts with an improved activity and stability. As a result, the library of NixPy catalysts has been enriched very rapidly, with the possibility of fine-tuning their surface adsorption properties through synergistic coupling with nearby elements or dopants as the basis of future practical implementation. The current review distils recent advancements in NixPy compounds/hybrids and their application for HER, with a robust emphasis on breakthroughs in composition refinement. Future perspectives for modulating the HER activity of NixPy compounds/hybrids, and the challenges that need to be overcome before their practical use in sustainable hydrogen production are also discussed.


Assuntos
Hidrogênio/química , Níquel/química , Água/química , Catálise , Complexos de Coordenação/síntese química , Complexos de Coordenação/química , Técnicas Eletroquímicas , Nanoestruturas/química , Elementos de Transição/química
16.
Biosens Bioelectron ; 144: 111697, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31536930

RESUMO

Surface plasmon resonance (SPR) has become a leading technique for in situ bioaffinity assay of diverse targets without need of fluorescent or enzymatic labeling. Nanomaterials-enhanced SPR sensors have developed rapidly and widened the application scope of SPR sensing technology. In this report we describe an ultrasensitive SPR biosensor for detecting carcinoembryonic antigen (CEA). Our SPR biosensor utilizes a Ti3C2-MXene-based sensing platform and multi-walled carbon nanotube (MWCNTs)-polydopamine (PDA)-Ag nanoparticle (AgNPs) signal enhancer. Ti3C2-MXene, a new class of two-dimensional (2D) transition metal carbides, offers a large hydrophilic-biocompatible surface ideal for SPR biosensing. Ti3C2-MXene/AuNPs composites after synthesis are then decorated with staphylococcal protein A (SPA) to orient and immobilize monoclonal anti-CEA antibody (Ab1) through its Fc region. By introducing MWCNTs-PDA-AgNPs-polyclonal anti-CEA antibody (MWPAg-Ab2) conjugate combined with a sandwich format, the present method provides a dynamic range for CEA determination of 2×10-16 to 2×10-8 M and a detection limit of 0.07 fM. This biosensing approach demonstrates good reproducibility and high specificity for CEA in real serum samples providing a promising method to evaluate CEA in human serum for early diagnosis and monitoring of cancer.


Assuntos
Técnicas Biossensoriais , Antígeno Carcinoembrionário/isolamento & purificação , Nanopartículas Metálicas/química , Ressonância de Plasmônio de Superfície , Anticorpos Anti-Idiotípicos/química , Anticorpos Anti-Idiotípicos/imunologia , Antígeno Carcinoembrionário/química , Ouro/química , Humanos , Nanoestruturas/química , Nanotubos de Carbono/química , Prata/química , Elementos de Transição/química
17.
Dalton Trans ; 48(39): 14547-14565, 2019 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-31556418

RESUMO

Metallic radionuclides have been instrumental in the field of nuclear imaging for over half a century. While recent years have played witness to a dramatic rise in the use of radiometals as labels for chelator-bearing biomolecules, imaging agents based solely on coordination compounds of radiometals have long played a critical role in the discipline as well. In this work, we seek to provide a brief overview of metal complex-based radiopharmaceuticals for positron emission tomography (PET) and single photon emission computed tomography (SPECT). More specifically, we have focused on imaging agents in which the metal complex itself rather than a pendant biomolecule or targeting moiety is responsible for the in vivo behavior of the tracer. This family of compounds contains metal complexes based on an array of different nuclides as well as probes that have been used for the imaging of a variety of pathologies, including infection, inflammation, cancer, and heart disease. Indeed, two of the defining traits of transition metal complexes-modularity and redox chemistry-have both been creatively leveraged in the development of imaging agents. In light of our audience, particular attention is paid to structure and mechanism, though clinical data is addressed as well. Ultimately, it is our hope that this review will not only educate readers about some of the seminal work performed in this space over the last 30 years but also spur renewed interest in the creation of radiopharmaceuticals based on small metal complexes.


Assuntos
Quelantes/química , Complexos de Coordenação/química , Neoplasias/diagnóstico , Compostos Radiofarmacêuticos/química , Elementos de Transição/química , Animais , Humanos , Neoplasias/diagnóstico por imagem , Tomografia por Emissão de Pósitrons , Tomografia Computadorizada de Emissão de Fóton Único
18.
Nanoscale ; 11(34): 15770-15782, 2019 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-31424462

RESUMO

Multifunctional platforms will play a key role and gain more prominence in the field of personalized healthcare worldwide in the near future due to the ever-increasing number of patients suffering from cancer. Along with the development of efficient techniques for cancer treatment, a considerable effort should be devoted toward the exploration of an emerging class of materials with unique properties that might be beneficial in this context. Currently, 2D post-carbon materials, such as pnictogens (phosphorene, antimonene), transition metal dichalcogenides, and boron nitride, have become popular due to their efficient photothermal behavior, drug-loading capability, and low toxicity. This review underlines the recent progresses made in the abovementioned 2D materials for photothermal/photodynamic cancer therapies and their applicability in bioimaging applications.


Assuntos
Diagnóstico por Imagem , Portadores de Fármacos , Hipertermia Induzida , Nanoestruturas , Fototerapia , Elementos de Transição , Animais , Portadores de Fármacos/química , Portadores de Fármacos/uso terapêutico , Humanos , Nanoestruturas/química , Nanoestruturas/uso terapêutico , Neoplasias/diagnóstico por imagem , Neoplasias/metabolismo , Neoplasias/terapia , Elementos de Transição/química , Elementos de Transição/uso terapêutico
19.
Chem Pharm Bull (Tokyo) ; 67(8): 733-771, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31366825

RESUMO

Transition-metal nanoparticles (NPs) catalysts supported on solid material represent one of the most important subjects in organic synthesis due to their reliable carbon-carbon or carbon-heteroatom bond-forming cross-coupling reactions. Therefore methodologically and conceptually novel immobilization methods for nonprecious transition-metal NPs are currently required for the development of organic, inorganic, green, materials, and medicinal chemistry. We discovered a self-assembled Au-supported Pd NPs catalyst (SAPd(0)) and applied it as a catalyst to Suzuki-Miyaura coupling, Buchwald-Hartwig reaction, Carbon(sp2 and sp3)-Hydrogen bond functionalization, double carbonylation, removal of the allyl protecting groups of allyl esters, and redox switching. SAPd(0) comprises approximately 10 layers of self-assembled Pd(0) NPs, whose size is less than 5 nm on the surface of a sulfur-modified Au. The Pd NPs are wrapped in a sulfated p-xylene polymer matrix. We thought that the self-assembled Au-supported Pd NPs could be made by in situ metal NP and nanospace simultaneous organization (PSSO). This methodology involves 4 kinds of simultaneous procedures: i) reduction of a higher valence metal salt, ii) growth of metal NPs with appropriate size, iii) growth of a matrix with appropriate pores, and iv) wrapping of the metal NPs by matrix nanopores. This methodology is different from previously reported metal NPs-immobilizing methods, which use solid supports with preformed pores or coordination sites. We also applied the in situ PSSO method to prepare various immobilized transition-metal NPs, including base metals. For example, the in situ PSSO method can be applicable to easily prepare Ni, Ru, and Fe NPs with good recyclability and low metal leaching for use in organic synthesis.


Assuntos
Descoberta de Drogas , Nanopartículas Metálicas/química , Compostos Orgânicos/síntese química , Elementos de Transição/química , Catálise , Estrutura Molecular , Compostos Orgânicos/química
20.
Top Curr Chem (Cham) ; 377(5): 23, 2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31463700

RESUMO

Since the pioneering independent reports of Akiyama and Terada, the use of chiral phosphoric acids (CPAs) and derivatives as a versatile tool for asymmetric synthesis with good reactivity, regioselectivity, diastereoselectivity and enantioselectivity has emerged, forming an important part of the implementation of asymmetric counteranion-directed catalysis reported to date. In these achievements, the combination of metals with CPAs has enabled various catalytic modes beyond the scope of typical acid catalysis, such as relay catalysis, ion-pairing catalysis, and binary acid catalysis. The first-row transition metals (Sc-Zn) are considered to be sustainable transition metals and have received a great deal of attention. These naturally abundant metals display excellent Lewis acidity and function as powerful redox catalysts in synthesis involving both one and two-electron transfers. Hence, in this chapter, we summarize recent advances in the development of asymmetric reactions using a combination of first-row transition metals and CPAs. Furthermore, we provide a detailed discussion of the mechanisms involved in order to understand the interaction of the metal/phosphate and the origins of the asymmetric control of the transformations.


Assuntos
Alcenos/síntese química , Compostos Organometálicos/química , Ácidos Fosfóricos/química , Elementos de Transição/química , Alcenos/química , Catálise , Estrutura Molecular
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