261903-04-2Relevant articles and documents
Dinuclear cobalt complexes with a redox active biphenyl bridging ligand [Co2(BP)(tqa)2](PF6)2(H4BP = 4,4′-bis(3-tert-butyl-1,2-catechol), tqa = tris(2-quinolylmethyl)amine): structure and magnetic properties
Kuroda-Sowa, Takayoshi,Maekawa, Masahiko,Mibu, Takuto,Okubo, Takashi,Suenaga, Yusaku,Sugimoto, Kunihisa
supporting information, p. 9833 - 9841 (2021/07/28)
The biscatechol, H4BP (4,4′-bis(3-tert-butyl-1,2-catechol)) that can directly connect two redox active catechol moieties was synthesized. Also, tris(2-pyridylmethyl)amine (tpa), bis(2-pyridylmethyl)(2-quinolylmethyl)amine (bpqa), (2-pyridylmethyl)bis(2-quinolyl methyl)amine (pbqa), and tris (2-quinolylmethyl)amine (tqa) were synthesized as terminal ligands of the tetracoordinated tripod. In total, five different dinuclear Co complexes were synthesized from H4BP with various terminal ligands as follows, [Co2(BP)(tpa)2](PF6)2(1), [Co2(BP)(tpa)2](PF6)3(2), [Co2(BP)(bpqa)2](PF6)2(3), [Co2(BP)(pbqa)2](PF6)2(4), and [Co2(BP)(tqa)2](PF6)2(5). After a one-electron oxidation reaction of complex (1), complex (2), was isolated as a mixed valence state lsCoIII-[SQ-Cat]-lsCoIII, with an absorption intensity of about 1370 nm (intervalence charge transfer (IVCT) bands) in CH3CN solution. In addition, an investigation of the magnetic properties of the dinuclear Co complex (3) with SQUID showed that theχMTvalue gradually increased as the temperature increased from 280 to 380 K. Studies in the solid and solution states using electronic spectra, cyclic voltammetry and SQUID for the above complexes provide clear evidence for three different charge distributions: complexes (1) and (3) are CoIII-[Cat-Cat]-CoIII, complex (2) is CoIII-[Sq-Cat]-CoIII, complexes (4) and (5) are CoII-[Sq-Sq]-CoII. Of the five cobalt dinuclear complexes, only complex (3) shows evidence of the temperature dependence of the charge distribution, displaying a thermally induced valence tautomeric transition from the lsCoIII-[Cat-Cat]-lsCoIIIto hsCoII-[Sq-Sq]-hsCoIIin both solid and solution states. However, this valence tautomeric step is incomplete at 380 K, with the?χMT?value of hsCoII-[Sq-Sq]-hsCoII. This suggests that the steric hindrance of the quinolyl rings around the Co ion produces a coordination atmosphere that is weaker than that observed with pyridyl rings, which facilitates a change in the CoIIIions to CoII
Synthesis and structure-activity relationship studies of hydrazide-hydrazones as inhibitors of laccase from trametes versicolor
Giurg, Miros?aw,Maniak, Halina,Matyja, Konrad,Talma, Micha?,Trusek, Anna
supporting information, (2020/03/23)
A series of hydrazide-hydrazones 1-3, the imine derivatives of hydrazides and aldehydes bearing benzene rings, were screened as inhibitors of laccase from Trametes versicolor. Laccase is a copper-containing enzyme which inhibition might prevent or reduce the activity of the plant pathogens that produce it in various biochemical processes. The kinetic and molecular modeling studies were performed and for selected compounds, the docking results were discussed. Seven 4-hydroxybenzhydrazide (4-HBAH) derivatives exhibited micromolar activity Ki = 24-674 μM with the predicted and desirable competitive type of inhibition. The structure-activity relationship (SAR) analysis revealed that a slim salicylic aldehyde framework had a pivotal role in stabilization of the molecules near the substrate docking site. Furthermore, the presence of phenyl and bulky tert-butyl substituents in position 3 in salicylic aldehyde fragment favored strong interaction with the substrate-binding pocket in laccase. Both 3- and 4-HBAH derivatives containing larger 3-tert-butyl-5-methyl- or 3,5-di-tert-butyl-2-hydroxy-benzylidene unit, did not bind to the active site of laccase and, interestingly, acted as non-competitive (Ki = 32.0 μM) or uncompetitive (Ki = 17.9 μM) inhibitors, respectively. From the easily available laccase inhibitors only sodium azide, harmful to environment and non-specific, was over 6 times more active than the above compounds.
Reaction of 2,8-bis(o -hydroxyaryl)quinolines with group 4 metal alkyls resulting in three distinct coordination modes of the tridentate ligand. X-ray structure of complexes and performance as precursors in ethylene polymerization catalysis
Nifant'ev, Ilya E.,Ivchenko, Pavel V.,Bagrov, Vladimir V.,Nagy, Sandor M.,Mihan, Shahram,Winslow, Linda N.,Churakov, Andrei V.
supporting information, p. 2685 - 2692 (2013/06/27)
A series of bis(o-hydroxyphenyl)quinolines have been prepared, starting from 2,8-dibromoquinoline. Reaction of these new ligand precursors with group 4 tetrabenzyl complexes MBn4 results in benzyl substitution of the azine fragment with the formation of amide complexes (M = Ti) or amine complexes with an N-H fragment coordinated to the metal (M = Zr, Hf). The third structural type - Zr complexes where the aromatic system of the precursor remains intact - can be prepared through the reaction of the bis(o-hydroxyphenyl)quinolones with 4 mol of methyllithium, followed by ZrCl4. The new complexes result in active polymerization catalysts when activated with MAO/borate cocatalysts on silica supports, resulting in polyethylene copolymers with very high molecular weights and multimodal MWDs.
