We present a straightforward one-pot hydrothermal method for the synthesis of zirconia nanodispersions, leading to the formation of stable sols. By simply varying the nature of the stabilizer used, one can obtain a large variety of objects with different sizes, shapes and crystallinities. Our results demonstrate the crucial role played by aliphatic amino acids both during the formation of the objects and after, since their interaction with the surface of the inorganic crystals influences strongly the optical properties and colloidal stability of the latter. Importantly, the versatility of this method allows for the introduction of different dopants, increasing substantially the scope of applications that can be achieved with such nanoscale oxides. The high transparencies and the easy dispersibility of nanoparticles in different liquid matrixes ensure the formation of zirconia-based nanocomposites and ceramics with outstanding optical features for the orthopedic, dental, photonics and chemical sectors. This method can be easily scaled up, being already available for the production of high-quality zirconia nanodispersions at the industrial level.
Carbon and nitrogen‐co‐doped Se/NiSe2/CoSe2 nanocomposite as superior performance electrode material in hybrid supercapacitors
Metal selenides are essential electrode materials for promising electrochemical energy storage with comparable or improved electrochemical performance than metal oxides. Herein, Se/NiSe2/CoSe2 (S/NS/CS) is fabricated using a solvothermal approach with the assistance of polyethyleneimine, followed by annealing at different temperatures (300, 400, 500, and 600°C) for one hour under an argon atmosphere. After annealing, all electrodes’ physical and electrochemical properties were examined, which determined that the best electrode is NiCo2O4/NiO (NCO/NO) formed at 500°C. Another hydrothermal method uses NCO/NO with SeO2 as a selenium source to prepare S/NS/CS nanocomposite, with a specific surface architecture that enables easy ion movement and strong conductivity, giving it exceptional electrochemical energy storage properties. It exhibited a remarkable capacitance of 468 F g−1 at a current density of 0.5 A g−1. For practical applications, the hybrid S/NS/CS//AC device was designed using S/NS/CS as a positive electrode and commercial activated carbon (AC) as a negative electrode. The asymmetric device demonstrated an excellent capacitance of 142 F g−1 (189 C g−1) and a superb specific energy of 44 Wh kg−1 at a specific power of 840 W kg−1 at a current density of 1 A g−1, providing 80% capacity retention and 100% coulombic efficiency after 5000 cycles.
Advances in Fluorescent Nanosensors for Detection of Vitamin B12
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[ASAP] Characterization of Parallel-Stranded DNA Duplexes by Surface-Enhanced Raman Spectroscopy and Bromide-Modified Gold Nanoparticles
Analytical Chemistry
DOI: 10.1021/acs.analchem.3c05356
A Self‐regulated Process from Bench to Pilot Production of Non‐natural Heterocycles Using Halohydrin Dehalogenases.
Halohydrin dehalogenases (HHDHs) have demonstrated significant potential as biocatalysts for synthesizing industrial heterocyclic compounds and chiral alkanolamines from aromatic substrates with NaOCN that are not feasible through chemosynthesis. To further study the HHDH reaction in real industrial applications, a diverse panel of HHDHs has been screened for their ability to convert aliphatic cyclohexene oxide. By using the best HHDH variant in form of a whole cell biocatalyst, a novel chemical process, regulated by the cascaded chemoenzymatic reactions for pilot-scale ring-opening reactions, has been successfully developed. Using the best HHDH hit in whole-cell form provides a viable bio-catalytic approach for the synthesis of related fine chemicals. Our research provides a promising strategy for scaling up non-native ring-opening reactions from the laboratory to industrial applications.
Visible light mediated synthesis of 3‐indolmethyl chromones via the cyclization of o‐hydroxyaryl enaminones with 3‐indoleacetic acids catalyzed by gC3N4 adorned with Cu NPs
Copper nanoparticles (Cu2O NPs) supported on graphitic carbon nitride (g-C3N4) have been introduced as an effective heterogenous catalyst for the synthesis of 3-indolmethyl chromones (3a-q) under visible light conditions via the cyclization of o-hydroxyaryl enaminones with 3-indoleacetic acids. The catalyst was thoroughly characterized using various techniques such as FT-IR, PXRD, XPS, FE-SEM, EDX, TEM, and HR-TEM analysis. The optimized reaction conditions enabled the high yield production of a wide range of 3-indolmethyl chromones in a short timespan at room temperature under visible light and method was successfully applied to the gram-scale synthesis. Importantly, the catalyst could be reused for up to five cycles without significant decrease in its activity. This approach aligns with eco-friendly principles, demonstrating favorable green chemistry metrics for compound 3a, including process mass intensity (7.83), environmental impact factor (6.83), atom economy (67.56 %), reaction mass efficiency (60.76 %), chemical yield (92.37 %), mass intensity (1.64), mass productivity (60.97 %), carbon efficiency (69.15 %) and optimum efficiency (89.93 %).
Revisiting Stereoselective Propene Polymerization Mechanisms: Insights through the Activation Strain Model
The stereoelectronic factors responsible for stereoselectivity in propene polymerization with several metallocene and post-metallocene transition metal catalysts have been revisited using a combined approach of DFT calculations, the Activation Strain Model, Natural Energy Decomposition Analysis and a molecular descriptor (%VBur). There are in most cases two different paths leading to the formation of stereoerrors (SE), and the classical model does not suffice to fully understand stereoregulation. Improving stereoselectivity requires raising the energies of both SE insertion transition states. Our analyses show that the degrees of deformation of the active site (catalyst+chain) and the prochiral monomer differ for these two paths, and between different catalyst classes. Based on such analyses we discuss: a) the subtle differences in SE formation between stereoselective catalysts with different ligand frameworks; b) the reason for exceptional stereoselectivity reported for a special ansa-metallocene catalyst; c) the (double) stereocontrol origin for isoselective catalysts; d) the electronic contribution for isoselective catalysts generating SE by a modification of the ligand wrapping mode during the polymerization. Although this study will not immediately suggest new catalyst structures, we believe that understanding stereoregulation in great detail will increase our chances of success.
Late transition metal complexes of ferrocene‐containing nitrogen ligands: Coordination chemistry, electron transfer properties, and tumor cell viability
Heterobimetallic complexes containing ferrocene and late transition metal complexes with nitrogen ligands form different geometrical isomers, with distinct electrochemical features and antiproliferative activity.
Bis(2-picolyl)amine (bpa), iminodiacetamide (imda), and bis-1,2,3-triazole (bta) ferrocene ligands (L) with and without an aliphatic linker were prepared by multi-step synthesis. The cis-fac, trans-fac, or mer stereochemistry of their ML2 complexes with Ni(II), Cu(II), Cd(II), and Zn(II) was studied in the solid state (infrared [IR] and single-crystal X-ray diffraction [SC-XRD]), in solution (nuclear magnetic resonance [NMR] and cyclic voltammetry [CV]) and by density functional theory (DFT) calculations. Crystal structures were determined for bpa ligand 7, and complexes [Ni(1)2](NO3)2 (1 Ni ), [Cu(8)2]OTf2 (8 Cu ), [Ni(10b)2](NO3)2 (10b Ni ), and [Cu(10b)2]OTf2 (10b Cu ). The bond strength of the central metal ion to the ligand amine nitrogen atom was studied by NMR, electrochemistry, and DFT. The information on redox-active centers, electron transfer properties of ferrocene ligands (L), and their in situ complexation with zinc(II) and nickel(II) ions were obtained by voltammetric analysis. In addition, DFT calculations showed that the electron ionization in ML2 complexes occurs from one of the ferrocene units, leaving the electronic structure of the other ligand intact, while some of the expelled electron density is recovered by the adjacent amine through resonance. This effect is more pronounced in the free ligands, because the eventual amine resonance in ML2 needs to balance its Zn(II) coordination participation, which justifies why they show higher ionization energies over free ligands. Moreover, due to lower steric hindrance, the N(amino)–Zn(II) coordination is additionally stronger in 1:1 ML complexes, which makes their electron depletion further more demanding. If compared with the clinical drug cisplatin, complexes of bpa 1 Ni and imda 2 Ni showed a better effect on the viability of different tumor cell lines and better selectivity towards normal cells. Treatment with 1 Ni and 2 Ni causes an increase of cells in the S phase of the cell cycle and leads to the accumulation of cells in G0/G1. A decrease in the expression level of anti-apoptotic marker Bcl-2 upon treatment with both compounds together with increased amount of Annexin V-FITC positive cells implied apoptosis as the mode of cell death.
Synthesis, characterization, thermal, anticancer studies, and density functional theory for potentially active pyrimidine‐based complexes
The non-covalent index technique provides important evidence of different forces like H-bonding, van der Walls, and steric interaction. The RDG plot shows that the interaction increases and stabilized through either H-bond or steric interaction (more prominent and more scatter points). The most interaction and stability was for Co(II) complex.
This work aimed to create and characterize some new bioactive chelates of bis azodye ligand, 5-((2-hydroxy-4,6-dioxo-1,4,5,6-tetrahydropyrimidin-5-yl)diazenyl)naphthalen-1-yl)diazenyl) pyrimidine 2,4,6 (1H,3H,5H)-trione. Except for the Sm(III) chelate, which exhibited a (3M:1L) molar ratio, all chelates had a (2M:1L) stoichiometry. According to Fourier transform infrared spectroscopy (FT-IR), azo groups were not included in chelating with all ions except Sm(III), where just one azo group was coordinated. With the Ni(II) and Zn(II) ions, the ligand behaved as OON-tridentate moiety; with the Co(II) and Cu(II) ions, it behaved as ON-bidentate moiety. Co(II) and Cu(II) chelates had square planar structure, and Ni(II) and Zn(II) chelates had square pyramidal geometry. The chelates had greater thermal stability than the uncoordinated ligand due to the chelate's structure. [Sm3(H4L)(OH)7(NO3)2.H2O].4.5EtOH exhibited the maximum thermal stability, which may be due to the large number of solvent molecules and the high number of chelate rings. With the exception of the Sm(III) chelate, all of the examined chelates were more cytotoxic against MCF-7 and Hep-G2 cells than their parent ligand. With the exception of the Zn(II) chelate, which demonstrated activity on Hep-G2 rather than MCF-7, the effects of each metal chelate on the two cells were nearly equivalent. All of the studied chelates, especially Zn(II) and Co(II), were potent as antioxidants more than the native ligand. To support experimental findings, density functional theory (DFT) studies were performed via the CAM-B3LYP/LanL2DZ method, and the geometry of the ligand and its chelates had been validated.
CeOx‐induced oxygen vacancy‐enhanced Pt‐based titanium silicalite‐1 catalysts for selective conversion of levulinic acid
Figure 1 Illustration of oxygen vacancy-enhanced active sites of Pt0.7-Ce0.5/TS-1.
We constructed a series of Pt-based titanium-silicalite-1 (TS-1) bifunctional catalysts modified with Ce through a simple spin-coating impregnation method. Under the enhancement of oxygen vacancies, Pt0.7-Ce0.5/TS-1 exhibited excellent aqueous phase hydrogenation performance (with an LA conversion rate of 99.8% and GVL selectivity of 99.6%).
The selective conversion of levulinic acid (LA) obtained from lignocellulosic biomass represents a crucial pathway for producing the key value-added chemical compound γ-valerolactone (GVL). Herein, we constructed a series of Pt-based titanium-silicalite-1 (TS-1) bifunctional catalysts modified with rare earth metal Ce through a simple spin-coating impregnation method, and the catalytic performance was significantly improved compared to the unmodified Pt1.2/TS-1. Pt0.7-Ce0.5/TS-1 exhibited the best aqueous-phase catalytic activity (with a GVL yield of 99.4%). The introduction of CeOx can reduce the particle size of Pt nanoparticles and promote the formation of electron-rich Pt species while delivering abundant oxygen vacancies (OV) for the catalysts. The characterization and testing results highlight the synergistic effect of OV and electron-rich Pt sites on the oriented adsorption and selective hydrogenation of LA, providing new insights into constructing more efficient noble metal-based zeolite catalysts for biomass conversion.