Sanaei-Rad, SalehehGhasemzadeh, Mohammad AliAghaei, Seyyed Soheil
9页
查看更多>>摘要：Metal-organic frameworks (MOFs) a developing class of porous materials constructed from metal ions or organic linkers have attracted increasing consideration in recent years. The exclusive properties of MOFs make them promising candidates as drug delivery hosts. In this study, we have investigated the novel metal-organic framework including ZnFe2O4/IRMOF-3/GO for the delivery of tetracycline antibiotic. The spectral analyzes including Fourier transform infrared (FT-IR), scanning electron microscope (SEM), X-ray crystallography (XRD), energy-dispersive X-ray spectroscopy (EDX), thermal gravimetric analysis (TGA), and brunauer emmett teller (BET) showed the successful preparation of ZnFe2O4/IRMOF-3/GO and ZnFe2O4/IRMOF-3/GO/tetracycline. The obtained results demonstrated that 87% of the tetracycline (TC) was loaded on the ZnFe2O4/IRMOF-3/GO framework. Moreover, drug release study was performed in phosphate buffer saline (pH: 7.4), and acetate buffer (pH: 5) solutions, which showed 88% and 75% release within 72 h, respectively. In order to evaluate the antibacterial activities of the pure tetracycline, ZnFe2O4/IRMOF-3/GO and ZnFe2O4/IRMOF-3/GO/TC against S. aureus and P. aeruginosa bacteria, we performed agar-well diffusion method to screen antimicrobial activities. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Metal catalyzed hydroformylation of alkenes is an atom economic transformation to construct useful aldehydes and is being industrially practiced for decades. The most commonly used metal for this transformation on an industrial scale is rhodium. However, rhodium is rare, costly, and is depleting at a skyrocketing rate. Therefore, finding a suitable alternative to rhodium for metal-catalyzed hydroformylation has been on the radar of many academic and industrial researchers. This review presents the scientific advancements reported in the hydroformylation reaction using metals other than rhodium. An overview of recent progress in palladium, iridium, ruthenium, cobalt, platinum, and iron-catalyzed hydroformylation is presented. Hydroformylation of alkenes and alkynes, using syngas as well as syngas surrogates is examined. The evaluation of the current status of non-rhodium metals in hydroformylation suggests that the field is still in a nascent stage and, except cobalt, no other metal poses a significant challenge to the dominance of rhodium. Deep mechanistic understanding of rate-limiting elementary steps in the non-rhodium metals is largely missing and thus only limited success is reported. Intense research on ligand design, mechanistic understanding, and choice of non-rhodium metal precursors may change this scenario in near future. (c) 2021 Elsevier B.V. All rights reserved.
Shamna, SalahudeenFairoosa, JaleelAfsina, C. M. A.Anilkumar, Gopinathan...
33页
查看更多>>摘要：A B S T R A C T Hydrosilylation is the unique reactions for the inclusion of silicon hydrides across C-C multiple bonds. Which is an efficient method for the formation of organosilicon compounds and represents the most significant reactions in silicon chemistry. Silasubstitution has received increasing attention in various fields of chemistry due to its low toxicity, ease of isolation and storage, favourable metabolic profiles and stability through multistep synthetic sequences without degradation. Hydrosilylation is mainly carried out in the presence of a metal catalyst like Pd, Ru and Pt. Karstedt's and Speier's catalysts are mainly accepted in these areas for decades. Improvement of more selective, cheap and efficient catalyst systems is still needed for more inexpensive production of organosilicon materials having superior properties. In the area of palladium catalysts, further developments have been made to improve the activity and selectivity in the past twelve years. This review comprehends the recent advances in Palladium-catalysed hydrosilylation reactions reported in the last twelve years from 2008 to 2020. (c) 2021 Elsevier B.V. All rights reserved.
Imran, MuhammadHasnain, MuhammadIqbal, Muhammad AdnanChaudhary, Sidra...
6页
查看更多>>摘要：N-alkylated imidazole derivatives (1a-1b), mono-azolium salts (SL2-SL3) and their symmetrically (SC2) and non-symmetrically (SC3) substituted mercury(II)-N-heterocyclic carbene (Hg(II)-NHC) complexes were synthesized by using "oxide route". The characterization was done by using physical (i.e., solubility, melting point determination, compound microscopic analysis) and spectral (i.e., UV-Visible spectroscopy, FT-IR spectroscopy, H-1 and C-13 NMR spectroscopy) methods. Chemical equilibrium between monomeric and dimeric structures of bromide-bridging Hg(II)-NHC complexes was also observed in the presence of solvent. Photo-catalytic degradation rate of two environmentally polluting dyes i.e., methylene blue (MR) and congo red (CR), was investigated by using compound 1 (SC2) and compound 2 (SC3) which demonstrated that the compound 2 had maximum degradation rate in the range of 70-80% as compared to the compound 1 (60-70% ). (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：A new series of platinum(II)-containing donor-acceptor (D-A) dimesitylborane-based complexes PT1-PT4 have been successfully synthesized in reasonable yields. The photophysical and electrochemical properties have also been investigated. Complexes PT1-PT4 have narrow energy bandgaps within 1.69-1.74 eV and broad absorption bands within 240-700 nm, which would be suitable candidates for the fabrication of devices in bulk heterojunction (BHJ) solar cells. The devices based on PT4, which has the longest pi-rconjugated framework, showed the highest PCE of 3.07% among all the devices with high open-circuit voltage (V-oc) of 0.92 V, short-circuit photocurrent density (J(sc)) of 7.95 mA cm(-2) and fill factor (FF) of 0.42 at the optimized active layer thickness of 85 nm. These complexes illustrate the potential of solution-processible metallo-organic D-A complexes for efficient power generation in photovoltaic implementation. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Chemical reactivity descriptors are significant tools to study various systems and processes. In order to explore their role in the prediction of catalytic activity, we have presented a Quantitative Structure-Activity Relationship (QSAR) model based on some of these descriptors for a broad set of Ruthenium (14-electron) complexes for olefin metathesis reaction. The complexes are of the type LCl2Ru=CH2 where L corresponds to varied dative ligands. It is observed that the multivariate QSAR model is able to correlate descriptors with the catalytic activities of the selected complexes nicely. The study is hasty, cost-effective and mimics the experimental activity trends for Grubbs Ru-catalysts. Chemically, it is noted that complexes with a bulky ligand present an increased catalytic activity as they lead towards the formation of an intermediate (metallacyclobutane) with lower steric crowding. Hence, it is suggested that employing chemical reactivity descriptors in multivariate models together with other crucial descriptors can offer a realistic means for activity prediction and catalyst development in case of olefin metathesis or any other organometallic reaction. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Novel catechol spiroborates (L(1-5)B) were prepared from the reaction of the corresponding Schiff base (L(1-5)H) ligands, boric acid, and 3,5-di-ten-butyl catechol under favorable reaction conditions. The synthesized all compounds were characterized by NMR spectra, FT-IR spectra, UV-Vis spectra, LC-MS/MS spectra, fluorescence spectra, elemental analysis as well as the melting point. The optical properties of the Schiff base ligands and catechol spiroborates were investigated using - and fluorescence spectra in the C2H5OH. The antioxidant activities of newly synthesized Schiff base ligands and their catechol spiroborates were investigated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability and reducing power ability. Among the synthesized catechol spiroborates, (L2B) exhibited the maximum radical scavenging (91.5 +/- 2.11%) and reducing power activity (0.654 +/- 0.015) at a concentration of 200.0 mu g/mL. Antibacterial activity was determined using 3 Gram positive and 2 Gram negative bacteria by disk diffusion method. Schiff base (L2H) was found to be effective against all test bacteria used. Besides, the DNA binding activity of the catechol spiroborates was determined using Calf Thymus DNA, and the DNA cleavage activity was determined using pBR-322 plasmid DNA by agarose gel electrophoresis method. (C) 2021 Elsevier B.V. All rights reserved.
Milov, Alexey A.Minyaev, Ruslan M.Minkin, Vladimir I.
5页
查看更多>>摘要：The competing multicenter bonding mechanisms (3c-4e and 5c-6e flip-flop effect), defining the structures and stability of the symmetric Group 14 bis-atranes RX(YCH2CH2)(3)N(CH2CH2Y)(3)XR and their analogs RX(YCH2CH2)(3)P(CH2CH2Y)(3)XR were investigated based on the density functional theory B3LYP/QZVP and M06/def2TZVP calculations and the AIM analysis of electronic distribution in molecules of the hypervalent compounds. Flip-flop effect was detected in bis-atranes (for X=Sn, Pb) and for all X centers in the case of phosphorus-containing analogs. Barriers do not exceed 1 kcal/mol for bis-atranes and do not exceed 14 kcal/mol for systems with phosphorus. (C) 2021 Elsevier B.V. All rights reserved.
Shroot, StephaniePrior, Timothy J.Wiles, CharlotteMurray, Benjamin S....
7页
查看更多>>摘要：The synthesis and characterisation of a small series of tethered ruthenium(II) eta(6)-arene complexes is described, where a single benzylic substituent is examined as a route to enforcing chirality at the metal centre upon ligation of a tethered bidentate ligand. The application of these complexes as catalysts in the asymmetric transfer hydrogenation of ketones is described, with moderate enantioselectivities confirming the validity of the approach. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Eight neutral luminescent cyclometalated platinum(II) complexes with general formula (piq)Pt(N boolean AND O) and (piq)Pt(N<^>P), where piq = 1-phenylisoquinoline, N boolean AND O = deprotonated (2-(1H-benzimidazole)-phenyl)diphenylphosphine oxide derivatives and N boolean AND P = deprotonated (2-(1H-benzimidazole)-phenyl)diphenylphosphine derivatives, have been synthesized and characterized. These complexes display distorted square-planar molecular geometries around platinum(II) centers without obvious pi-pi interactions and Pt-Pt metallophilic interactions in the crystal lattice, due to the presence of sterically bulky N boolean AND O and N boolean AND P benzimidazole ancillary ligands. Hence, these complexes exhibit good monomeric emissions with the luminescent quantum yields of 15%-23%, which are far more than that of (piq)Pt(acac) (0.9%) in dichloromethane (DCM) at 298 K. The emission colors of platinum(II) complexes can be finely tuned in the range 600-645 nm by changing the chelating types of ancillary ligands. The structured emission combined with microsecond emission lifetimes and the support of TD-DFT calculations for these complexes indicate that their emissions mainly come from an admixture of intraligand (3ILCT) and metal-to-ligand charge transfer (3 MLCT). (C) 2021 Elsevier B.V. All rights reserved.
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