ABSTRACT
In this study, a series of structurally rigid cyclooctyl-fused iminopyridine iron complexes, [L2FeCl][FeCl4] and [2L3Fe][Cl][3FeCl4], was synthesized via a one-pot method and investigated as precatalysts in conjunction with methylaluminoxane for isoprene (Ip) polymerization. Combined characterization through FTIR analysis, elemental analysis and single crystal XRD analysis fully verified the structure of these complexes. The most active iron complex, FeH, exhibited a trisligated nature, with its cation adopting an octahedral geometry around the metal center. In contrast, all the other iron complexes (Fe2Me, Fe2Et, Fe2iPr, Fe3Me, Fe2Et,Me) displayed bisligated configurations, with distorted trigonal bipyramidal geometry of cations. During isoprene polymerization, the extent of steric hindrance of the ligand framework exerted a significant impact on catalytic performance. The FeH precatalyst with less steric hindrance demonstrated excellent performance, producing high molecular weight polyisoprenes with conversions exceeding 99% for 4000 equiv. of monomer. Even at very low catalyst loadings, as low as 0.0025 mol% (Fe/Ip), the polymerization of isoprene could proceed smoothly with an exceptionally high activity of 4.0 × 106 gPI (molFe, h)-1. Moreover, this precatalyst exhibited good thermal stability, maintaining high activity levels (typically 105 gPI (molFe, h)-1) across a broad temperature range from -20 °C to 100 °C. Additionally, by adjusting steric substituents and the reaction temperature, the 1,4/3,4 regioselectivity could be modulated from 9/91 to 69/31 while maintaining a high stereoselectivity of cis-1,4 structures (cis/trans: >99/1).
ABSTRACT
Polystichum lonchitis L. is a fern belonging to the family Dryopteridaceae. The present study was conducted to evaluate its pharmacological, antioxidant, and phytochemical properties, and to conduct GC-MS screening of P. lonchitis. The acetic acid-induced writhing test, yeast-induced hyperpyrexia method, carrageenan-induced rat paw edema model, and charcoal meal test model were carried out to assess analgesic, antipyretic, anti-inflammatory, and antispasmodic activity, respectively. DPPH was used as an antioxidant, while the phytochemical screening was conducted using standard scientific methods. Among the pharmacological activities, the most significant effects were observed in the analgesic and anti-inflammatory activities, followed by the antipyretic and antispasmodic activities, at a dose of 450 mg/kg after the 4th hour, compared with 150 mg/kg and 300 mg/kg. For the evaluation of antioxidant activities, the most significant results were detected in the methanolic and aqueous extracts. The detection of flavonoids and phenol occurred most significantly in the methanolic extract, and then in the ethanolic and aqueous extracts. The main compounds detected using GC-MS analysis with a high metabolic rate was ð¼-D-Galactopyranoside, which had a metabolic rate of 0.851, and methyl and n-hexadecanoic, which had a metabolic rate of 0.972. Overall, the results suggested that P. lonchitis had a strong potential for pharmacological activities. The suggested assessment provided a way to isolate the bioactive constituents and will help to provide new medicines with fewer side effects. Due to the fern's effectiveness against various diseases, the results provide clear evidence that they also have the potential to cure various diseases.