Iron(III) complexes with meta-substituted bis(arylimino)pyridine ligands: Catalyst precursors for the selective oligomerization of ethylene

Research progress of iron-based catalysts for selective oligomerization of ethylene

Linear α-olefins are widely used as raw materials in the chemical industry. Selective ethylene oligomerization is an important development direction of the linear α-olefin production process. Iron-based catalysts have become a research hotspot in selective ethylene oligomerization due to their advantages like high activity, high selectivity and convenience of adjusting their ligand structures. In this paper, the research progress of catalysts for selective oligomerization of ethylene was reviewed in terms of the cocatalysts, ligand structure, and immobilization of homogeneous catalysts.

Synthesis, Insecticidal Evaluation, and 3D-QASR of Novel Anthranilic Diamide Derivatives Containing N-Arylpyrrole as Potential Ryanodine Receptor Activators

To cope with the global food shortage and insect pest, there is an urgent need to discover new pesticides with novel modes of actions. Ryanodine receptor (RyR) insecticides showed great promise in integrated pest management. Herein, we report the synthesis of novel anthranilic diamide derivatives incorporating pyrrole moieties targeting at insect RyRs. The structures were confirmed by ¹H NMR, ¹³C NMR, ¹⁹F NMR, and high-resolution mass spectrometry. The preliminary bioassay results indicated that most of the title compounds showed good to excellent insecticidal activities against the oriental armyworm (Mythimna separata) and diamondback moth (Plutella xylostella). For the oriental armyworm, Ij displayed the same level of larvicidal activity as the positive control chlorantraniliprole, with an LC₅₀ value of 0.21 mg/L. For the diamondback moth, In, Io, Ip, and Iq exhibited higher insecticidal activities than chlorantraniliprole. In particular, In had 50% larvicidal activity at 0.00001 mg/L. The calcium imaging technique was applied to study the effect of Ij, In, and Ip on the intracellular calcium ion concentration ([Ca²⁺]_i) in central neurons isolated from the oriental armyworm. The results indicated that the tested compounds, such as chlorantraniliprole, could activate the insect RyRs. Furthermore, comparative molecular field analysis and density functional theory calculations were carried out to study the structure-activity relationship.

Directing the Self-Assembly Behaviour of Porphyrin-Based Supramolecular Systems

The self-assembly behaviour of a library of tetra-amidated porphyrin molecules decorated with a variety of solubilizing wedges is investigated as dilute solutions in methylcyclohexane. Small changes in the solubilising wedge of the porphyrins resulted in different aggregated states, as evidenced by CD and UV/Vis absorption spectroscopy. The porphyrins form co-facially stacked H-aggregates, slip-stacked J-aggregates or a mixture of both. Detailed thermodynamic and kinetic analysis showed that in all cases the formation of J-aggregates proceeds via an isodesmic mechanism whereas H-aggregates are formed via a cooperative mechanism. It is shown that these aggregates assemble in a parallel pathway, in which both compete for the monomer, compared to a sequential pathway, in which one of the aggregates interconverts into the other. Interestingly, kinetic analysis of porphyrins that only form H-aggregates in thermodynamic equilibrium revealed that the competing pathway towards J-aggregates is operational in these systems as well. Our findings show that the balance between H- and J-aggregates depends on remarkably small changes in the architecture of the solubilising wedges.

Av. Horacio Macedo, 2.030 Centro de Tecnologia, Bloco J. Rio de Janeiro, RJ. Brasil, Pereira L, Simoes MDO, Marques MDF, Universidade Federal do Rio de Janeiro, Instituto de Macromoleculas Eloisa Mano IMA-UFRJ, Cidade Universitaria. Av. Horacio Macedo, 2.030 Centro de Tecnologia, Bloco J. Rio de Janeiro, RJ. Brasil, Universidade Federal do Rio de Janeiro, Instituto de Macromoleculas Eloisa Mano IMA-UFRJ, Cidade Universitaria. Av. Horacio Macedo, 2.030 Centro de Tecnologia, Bloco J. Rio de Janeiro, RJ. Brasil, Universidade Federal do Rio de Janeiro, Instituto de Macromoleculas Eloisa Mano IMA-UFRJ, Cidade Universitaria. Av. Horacio Macedo, 2.030 Centro de Tecnologia, Bloco J. Rio de Janeiro, RJ. Brasil. Synthesis and Evaluation of New Bis(imino) Pyridine Based Catalysts for Ethylene Polymerization

Three-component catalytic systems based on 2,6-bis(imino) pyridine iron(II) chloride were synthesized from different ligands, which provided new alternative catalysts for polymerization of ethylene. The synthesized catalysts were characterized by Fourier transform infrared spectroscopy (FTIR), and the lack of absorption bands was observed in the region related to the carbonyl, as well as the presence of bands in the region of imino groups corresponding to C=N bonds. Coordination with Fe was also carried out. The structure of the ligands and the new catalysts were confirmed by the elemental analysis (CHN), and 1H- and 13C-nuclear magnetic resonance spectroscopy. In ethylene polymerization with methylaluminoxane as a cocatalyst, the activity of catalyst C1 was high. Although this catalyst structure contains sterically bulky ligands, the metal center was not sufficiently protected allowing transfer reactions, producing polyethylene with a low molar mass and melting temperature.

Research on controllable degradation of sulfonylurea herbicides

Through studying structure, bioassay and soil degradation tri-factor relationship, potential controllable degradation of SU was firstly explored and summarized.

Exploring the effects of phenolic compounds on bis(imino)pyridine iron-catalyzed ethylene oligomerization

Polymer formation could be efficiently retarded with the activation of phenol-modified MAOs in the iron-catalyzed oligomerization of ethylene.