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1.
Chemosphere ; 286(Pt 1): 131607, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34311398

RESUMO

MXene, comprised of two-dimensional transition metal carbides/nitride, has emerged as a novel material suitable for environmental remediation of toxic compounds. Due to their inherent and superior physical and chemical properties, MXene is employed in separation techniques like photocatalysis, adsorption, and membrane separation. MXene is equipped with a highly hydrophilic surface, ion exchange property, and robust surface functional groups. In this review paper, a comprehensive discussion on the structural patterns, preparation, properties of MXene and its application for the removal of toxic pollutants like Radionuclide, Uranium, Thorium, and dyes is presented. The mechanism of removal of the pollutants by MXene is extensively reviewed. Synthesis of MXene based membranes, their properties, and application for water purification and properties were also discussed. This review will be highly helpful to understand critically the methods of synthesis and use of MXene material for priority environmental pollutants removal. In addition, the challenges behind the synthesis and use of MXene for decontamination of pollutants were reviewed and reported.


Assuntos
Recuperação e Remediação Ambiental , Elementos de Transição , Purificação da Água , Adsorção , Corantes
2.
Chimia (Aarau) ; 75(11): 967-971, 2021 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-34798919

RESUMO

In recent years, transition-metal-catalyzed C-H functionalization has emerged as a potentially greener alternative to classic cross-couplings and as a powerful tool to access complex functional molecules with improved step-economy. This short account relates our experience of industrial collaborations in C(sp³)-H bond activation, which were key to the development of this topic in our group. The synthesis of the antianginal drug Ivabradine led us to develop a general approach to benzocyclobutenes, which were further employed in peri cyclic reactions. A follow-up study led us to discover a new method to construct arylcyclopropanes via double C-H activation and the coupling of two alkyl groups. Finally, targeting the herbicide Indaziflam contributed to develop C(sp³)-H activation as a powerful tool to access a variety of relevant indane motifs. We hope that these successful stories will help to stimulate further fruitful Industry-Academia collaborations in the field of synthetic chemistry.


Assuntos
Elementos de Transição , Catálise , Seguimentos
3.
Nano Lett ; 21(18): 7602-7608, 2021 09 22.
Artigo em Inglês | MEDLINE | ID: mdl-34468150

RESUMO

Two-dimensional transition metal dichalcogenides are promising candidates for ultrathin light modulators due to their highly tunable excitonic resonances at visible and near-infrared wavelengths. At cryogenic temperatures, large excitonic reflectivity in monolayer molybdenum diselenide (MoSe2) has been shown, but the permittivity and index modulation have not been studied. Here, we demonstrate large gate-tunability of complex refractive index in monolayer MoSe2 by Fermi level modulation and study the doping dependence of the A and B excitonic resonances for temperatures between 4 and 150 K. By tuning the charge density, we observe both temperature- and carrier-dependent epsilon-near-zero response in the permittivity and transition from metallic to dielectric near the A exciton energy. We attribute the dynamic control of the refractive index to the interplay between radiative and non-radiative decay channels that are tuned upon gating. Our results suggest the potential of monolayer MoSe2 as an active material for emerging photonics applications.


Assuntos
Molibdênio , Elementos de Transição , Óptica e Fotônica , Refratometria , Temperatura
4.
Nano Lett ; 21(18): 7815-7822, 2021 09 22.
Artigo em Inglês | MEDLINE | ID: mdl-34491064

RESUMO

Chemical etching can create novel structures inaccessible by growth and provide complementary understanding on the growth mechanisms of complex nanostructures. Screw dislocation-driven growth influences the layer stackings of transition metal dichalcogenides (MX2) resulting in complex spiral morphologies. Herein, we experimentally and theoretically study the etching of screw dislocated WS2 and WSe2 nanostructures using H2O2 etchant. The kinetic Wulff constructions and Monte Carlo simulations establish the etching principles of single MX2 layers. Atomic force microscopy characterization reveals diverse etching morphology evolution behaviors around the dislocation cores and along the exterior edges, including triangular, hexagonal, or truncated hexagonal holes and smooth or rough edges. These behaviors are influenced by the edge orientations, layer stackings, and the strain of screw dislocations. Ab initio calculation and kinetic Monte Carlo simulations support the experimental observations and provide further mechanistic insights. This knowledge can help one to understand more complex structures created by screw dislocations through etching.


Assuntos
Nanoestruturas , Elementos de Transição , Parafusos Ósseos , Peróxido de Hidrogênio , Microscopia de Força Atômica
5.
Nano Lett ; 21(19): 8409-8417, 2021 10 13.
Artigo em Inglês | MEDLINE | ID: mdl-34591493

RESUMO

The dielectric screening from the disordered media surrounding atomically thin transition metal dichalcogenides (TMDs) monolayers modifies the effective defect energy levels and thereby the transport and energy dynamics of excitons. In this work, we study this effect in WSe2 monolayers for different combinations of surrounding dielectric media. Specifically, we study the source of the anomalous diffusion of excitons in the WSe2 monolayer and attribute the anomaly to the modification of the energy distribution of defect states in different disordered dielectric environments. We use this insight to manipulate exciton transport by engineering the dielectric environment using a graphene/hexagonal boron nitride (h-BN) moiré superlattice. Finally, we observe that the effect of dielectric disorder is even more significant at high excitation fluences, contributing to the nonequilibrium phonon drag effect. These results provide an important step toward achieving control over the exciton energy transport for next-generation opto-excitonic devices.


Assuntos
Grafite , Elementos de Transição , Difusão , Fônons , Semicondutores
6.
Chem Commun (Camb) ; 57(77): 9807-9819, 2021 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-34486592

RESUMO

(1,n) annulation reactions using (de)-hydrogenative coupling with alcohols or diols represent a straightforward technique for the synthesis of cyclic moieties. Utilization of such renewable resources for chemical transformations in a one-pot manner is the main focus, which avoids generation of stoichiometric waste. Application of such (1,n) annulation approaches drives the catalysis research in a more sustainable way and generates dihydrogen and water as by-products. This feature article highlights the recent (from 2015 to March 2021) progress in the synthesis of stereo-selective cycloalkanes and cycloalkenes, saturated and unsaturated N-heterocycles (cyclic amine, imide, lactam, tetrahydro ß-carboline, quinazoline, quinazolinone, 1,3,5-triazines etc.) and other N-heterocycles with the formation of multiple bonds in a one pot operation. Mechanistic studies, new catalytic approaches, and synthetic applications including drug synthesis and post-drug derivatization, scope, and limitations are discussed.


Assuntos
Álcoois/química , Elementos de Transição/química , Alcanos/síntese química , Alcanos/química , Alcenos/síntese química , Alcenos/química , Catálise , Compostos Heterocíclicos/síntese química , Compostos Heterocíclicos/química , Hidrogenação , Estrutura Molecular
7.
J Org Chem ; 86(19): 13693-13701, 2021 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-34529434

RESUMO

A transition-metal-free postmodification of the Groebke-Blackburn-Bienaymé (GBB) reaction for the synthesis of spiro[chromene-imidazo[1,2-a]pyridin]-3'-imine was discovered. The unusual transformation represents the first example of activation and the reaction of the imidazole carbon atom. In this postcondensational modification, KOt-Bu acts as a base, which, after the isomerization of an alkyne moiety to allene, causes the next unique nucleophilic reaction of the imidazole carbon atom that results in spirocyclic structures. The proposed reaction mechanism was confirmed based on the DFT calculations.


Assuntos
Iminas , Elementos de Transição , Alcinos , Benzopiranos , Ciclização
8.
Chemistry ; 27(64): 15914-15917, 2021 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-34529306

RESUMO

A rare three-coordinate germanone [IPrN]2 Ge=O (IPrN=bis(2,6-diisopropylphenyl)imidazolin-2-imino) was successfully isolated. The germanone has a rather high thermal stability in arene solvent, and no detectable change was observed at 80 °C for at least one week. However, high thermal stability of [IPrN]2 Ge=O does not prevent its reactivity toward small molecules. Structural analysis and initial reactivity studies revealed the highly polarized nature of the terminal Ge=O bond. Besides, the addition of phenylacetylene, as well as O-atom transfer with 2,6-dimethylphenyl isocyanide make it a mimic of nucleophilic transition-metal oxides. Mechanism for O-atom transfer reaction was investigated via DFT calculations, which revealed that the reaction proceeds via a [2+2] cycloaddition intermediate.


Assuntos
Elementos de Transição , Cianetos
9.
Talanta ; 235: 122726, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517594

RESUMO

Two-dimensional (2D) transition metal carbides, carbonitrides, and nitrides (MXene) have emerged as a rising family of atomic layered nanomaterials which undergoes intensive investigations in interdisciplinary applications. The large surface-to-volume ratio, excellent mechanical strength, desirable biocompatibility, along with tunable electronic and optical properties, render 2D MXenes exceptional attractive as versatile nanoplatforms for biosensing. Herein, advanced progress and novel paradigms of MXene-based biosensors are reviewed, focusing on the combination of MXenes with various detection techniques that promotes target recognition and signal transducing. Regarding the nature of transducing signals, MXene-based biosensors are categorized into two groups where MXenes serve as electrical platforms or optical platforms, respectively. The merits of MXenes are critically compared with other 2D materials to illustrate the distinctive advantages of MXenes in biosensing, while challenges such as environmental vulnerability was discussed to guide the sensor design. Facing with the rapid development of wearable electronics and internet of medical things, as well as escalating demanding in precision medicine, perspectives are provided to elucidate the potential of MXenes in propelling advances in these trending biomedical applications.


Assuntos
Técnicas Biossensoriais , Nanoestruturas , Elementos de Transição
10.
Chemistry ; 27(63): 15571-15604, 2021 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-34343374

RESUMO

Oxygen-bearing motifs, mainly the congener heterocycles are ubiquitous due to their presence in various natural products and bioactive scaffolds. Although in literature, several strategies have been developed for their synthesis, hydroalkoxylation of alkynes has come forward as a method of choice and has been used extensively. In particular, hydroalkoxylation of alkynes has gained enormous attention from the synthetic community due to the rapid access to a very useful and reactive synthetic intermediate like 'enol ether'. Furthermore, to manifold the utility of these methods, reports have been developed elaborating the generation of 'enol ether' using hydroalkoxylation and their usage in various reactions in cascade or tandem manner. This review focuses on recent development on the hydroalkoxylation of alkynes for the synthesis of oxygen-containing entities.


Assuntos
Alcinos , Elementos de Transição , Álcoois , Catálise , Éteres
11.
J Org Chem ; 86(17): 12247-12256, 2021 09 03.
Artigo em Inglês | MEDLINE | ID: mdl-34406002

RESUMO

The direct functionalization of N-heterocycles is a vital transformation for the development of pharmaceuticals, functional materials, and other chemical entities. Herein, the transition-metal-free alkylation and acylation of C(sp2)-H bonds in biologically relevant 2-benzoxazinones with 1,4-dihydropyridines as readily accessible radical surrogates is described. Excellent functional group compatibility and a broad substrate scope were attained. Gram-scale reaction and transformations of the synthesized adducts via Suzuki coupling with heteroaryl boronic acids demonstrated the synthetic potential of the developed protocol.


Assuntos
Di-Hidropiridinas , Elementos de Transição , Acilação , Alquilação , Benzoxazinas
12.
J Org Chem ; 86(15): 10288-10302, 2021 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-34288680

RESUMO

2-Aminobenzothiazoles comprise a valuable structural motif, which prevails in versatile natural products and biologically active compounds. Herein, a switchable and scalable C-N coupling protocol was developed for the synthesis of these compounds from 2-chlorobenzothiazoles and primary amines. Gratifyingly, this protocol was achieved under transition-metal-free and solvent-free conditions. Moreover, introducing an appropriate amount of NaH completely switched the selectivity from mono- toward di-heteroarylation, and further investigations provided a rationale for this new finding. Furthermore, gram-scale synthesis of representative products 3a and 4a was realized by applying operationally simple and glovebox-free procedures, which revealed the practical usefulness of this work. Finally, evaluation of the quantitative green metrics provided evidence that our protocol was superior over the literature ones in terms of green chemistry and sustainability.


Assuntos
Aminas , Elementos de Transição , Solventes
13.
J Org Chem ; 86(15): 10407-10413, 2021 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-34314182

RESUMO

A base-mediated semihydrogenation of ynamides using p-toluenesulfonyl hydrazide as an inexpensive and easy-to-handle hydrogen donor is reported. This transition-metal-free protocol avoids overhydrogenation and reduction of other functional groups, generating the thermodynamically unfavorable Z-enamides exclusively.


Assuntos
Amidas , Elementos de Transição , Catálise , Hidrogenação , Estereoisomerismo
14.
Small ; 17(36): e2102396, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34331412

RESUMO

Combining NO removal and NH3 synthesis, electrochemical NO reduction reaction (NORR) toward NH3 is considered as a novel and attractive approach. However, exploring suitable catalysts for NO-to-NH3 conversion is still a formidable task due to the lack of a feasible method. Herein, utilizing systematic first-principles calculations, a rational strategy for screening efficient single-atom catalysts (SACs) for NO-to-NH3 conversion is reported. This strategy runs the gamut of stability, NO adsorbability, NORR activity, and NH3 selectivity. Taking transition metal atom embedded in C2 N (TM-C2 N) as an example, its validity is demonstrated and Zr-C2 N is selected as a stable NO-adsorbable NORR catalyst with high NH3 selectivity. Therefore, this work has established a theoretical landscape for screening SACs toward NO-to-NH3 conversion, which will contribute to the application of SACs for NORR and other electrochemical reactions.


Assuntos
Elementos de Transição , Catálise , Óxido Nítrico
15.
Org Lett ; 23(16): 6401-6406, 2021 08 20.
Artigo em Inglês | MEDLINE | ID: mdl-34319121

RESUMO

A transition-metal-free one-pot three-component annulation between diaryliodonium triflates, cyclic and acyclic aliphatic amines, and carbon disulfide providing a convenient and efficient access to biologically relevant S-aryl dithiocarbamates is developed. The reaction does not require metal, base, or any other additive and operates under mild and ambient conditions. This methodology is robust, scalable, and exhibits a broad substrate scope. The in silico analysis revealed that the majority of the compounds have a drug-likeness and good ADMET characteristics.


Assuntos
Aminas/química , Dissulfeto de Carbono/química , Tiocarbamatos/química , Elementos de Transição/química , Estrutura Molecular , Sais/química
16.
Inorg Chem ; 60(14): 10837-10847, 2021 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-34231358

RESUMO

Emission of harmful pollutants from different sources into the environment is a major problem nowadays. Organochlorine pesticides such as DDT (C14H9Cl5) are toxic, bio-accumulative, and regularly seen in water bodies, air, biota, and sediments. Various systems can be considered for minimizing the DDT (dichloro-diphenyl-trichloroethane) pollution. However, due to simplicity and acceptability, the adsorption method is the most popular method. Adsorption is gradually employed for the removal of both organic and inorganic pollutants found in soil and water. Thus, in this regard, efforts are being made to design inorganic nanoclusters (B12N12) encapsulated with late transition metals (Zn, Cu, Ni, Co, and Fe) for effective adsorption of DDT. In this context, detailed thermodynamics and quantum chemical study of all the designed systems have been carried out with the aid of density functional theory. The adsorption energy of DDT on metals cocooned in a nanocluster is found to be higher, and better adsorption energy values as compared to that of the pristine B12N12-DDT nanocluster have been reported. Further, analysis of the dipole moment, frontier molecular orbitals, molecular electrostatic potential plots, energy band gap, QNBO, and Fermi level suggested that the late-transition-metal-encapsulated inorganic B12N12 nanoclusters are efficient candidates for effective DDT adsorption. Lastly, the study of global descriptors of reactivity confirmed that the designed quantum mechanical systems are quite stable in nature with a good electrophilic index. Therefore, the recommendation has been made for these novel kinds of systems to deal with the development of DDT sensors.


Assuntos
DDT/química , DDT/isolamento & purificação , Poluentes Ambientais/química , Poluentes Ambientais/isolamento & purificação , Nanoestruturas/química , Teoria Quântica , Elementos de Transição/química , Adsorção , Modelos Moleculares , Conformação Molecular
17.
Small ; 17(32): e2100621, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34105241

RESUMO

Limited levels of UV exposure can be beneficial to the human body. However, the UV radiation present in the atmosphere can be damaging if levels of exposure exceed safe limits which depend on the individual the skin color. Hence, UV photochromic materials that respond to UV light by changing their color are powerful tools to sense radiation safety limits. Photochromic materials comprise either organic materials, inorganic transition metal oxides, or a hybrid combination of both. The photochromic behavior largely relies on charge transfer mechanisms and electronic band structures. These factors can be influenced by the structure and morphology, fabrication, composition, hybridization, and preparation of the photochromic materials, among others. Significant challenges are involved in realizing rapid photochromic change, which is repeatable, reversible with low fatigue, and behaving according to the desired application requirements. These challenges also relate to finding the right synergy between the photochromic materials used, the environment it is being used for, and the objectives that need to be achieved. In this review, the principles and applications of photochromic processes for transition metal oxides and hybrid materials, photocatalytic applications, and the outlook in the context of commercialized sensors in this field are presented.


Assuntos
Elementos de Transição , Raios Ultravioleta , Humanos , Óxidos
18.
Nat Commun ; 12(1): 3706, 2021 06 17.
Artigo em Inglês | MEDLINE | ID: mdl-34140488

RESUMO

Organometallic complexes are ubiquitous in chemistry and biology. Whereas their preparation has historically relied on ligand synthesis followed by coordination to metal centers, the ability to efficiently diversify their structures remains a synthetic challenge. A promising yet underdeveloped strategy involves the direct manipulation of ligands that are already bound to a metal center, also known as chemistry-on-the-complex. Herein, we introduce a versatile platform for on-the-complex annulation reactions using transient aryne intermediates. In one variant, organometallic complexes undergo transition metal-catalyzed annulations with in situ generated arynes to form up to six new carbon-carbon bonds. In the other variant, an organometallic complex bearing a free aryne is generated and intercepted in cycloaddition reactions to access unique scaffolds. Our studies, centered around privileged polypyridyl metal complexes, provide an effective strategy to annulate organometallic complexes and access complex metal-ligand scaffolds, while furthering the synthetic utility of strained intermediates in chemical synthesis.


Assuntos
Derivados de Benzeno/química , Complexos de Coordenação/química , Metais/química , Compostos Organometálicos/química , Carbono/química , Catálise , Complexos de Coordenação/síntese química , Ligantes , Compostos Organometálicos/síntese química , Paládio/química , Rutênio/química , Elementos de Transição/química
19.
J Org Chem ; 86(14): 9289-9298, 2021 07 16.
Artigo em Inglês | MEDLINE | ID: mdl-34185538

RESUMO

A transition metal-free method for de novo construction of diverse sulfonated pyrazoles from readily available sulfonyl hydrazides, 1,3-diketones, and sodium sulfinates was established under mild conditions. Pyrazoles bearing two different sulfonyl groups were obtained in one step. The method features a diversity of substituents of the pyrazole products and a remarkably simple work-up.


Assuntos
Sódio , Elementos de Transição , Cetonas , Pirazóis , Temperatura
20.
Chem Asian J ; 16(14): 1864-1877, 2021 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-34014613

RESUMO

Quaternary stereocenters are of great importance to the three-dimensionality and enhanced properties of new molecules, but the synthetic challenges in creating quaternary stereocenters greatly hinder their wide use in drug discovery, organic material design, and natural product synthesis. The asymmetric allylic alkylation (AAA) of allylic substrates has proven to be a powerful methodology for enantioselective formation of structure skeletons bearing single or more quaternary carbon centers in modern asymmetric organocatalysis. AAA has certain advantages in constructing the tetrasubstituted stereocenters, including but not limited to mild reactive conditions, effective reaction rates, new functional group introduction, and carbon chains length extension. This review outlines the key considerations in the application of AAA reactions and summarizes the recent progress of AAA reactions in the enantioselective synthesis of products containing quaternary stereocenters. Meanwhile, a detailed discussion of the AAA reactions such as ligands, scope of substrates, transformations and the general reaction mechanisms is also provided. We hope this review could stimulate further advances in much broader areas, including organic synthesis, asymmetric catalysis, C-H activation, and symmetrical pharmaceutical chemistry.


Assuntos
Compostos Alílicos/síntese química , Alquilação , Catálise , Estereoisomerismo , Elementos de Transição/química
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