One‐ and two‐electron oxidized CuII complexes of Schiff base ligands with para‐substituted phenolate moieties were synthesized and characterized. The crystal structure of the one‐electron oxidized methylthio‐substituted complex [Cu(MeS‐salen)]SbCl6 revealed the intermolecular π‐π stacking interaction of the two phenolate moieties with those of the neighboring complex cations to form the one‐dimensional chain. Such a π‐π stacking interaction could not be detected in the two‐electron oxidized complex [Cu(MeS‐salen)](SbCl6)2 and the oxidized methoxy‐substituted complexes [Cu(MeO‐salen)](SbF6)n (n=1, 2). Magnetic study of [Cu(MeO‐salen)]SbF6 showed a weak antiferromagnetic interaction between the CuII ion and phenoxyl radical unpaired electron spins, while [Cu(MeS‐salen)]SbCl6 showed a ferromagnetism. Both of the two‐electron oxidized complexes exhibited a relatively strong magnetic interaction between the two radical electrons, while the signs of the electron spins are different.
In order to gain new insights into the effect of the π–π stacking interaction of the indole ring with the CuII–phenoxyl radical as seen in the active form of galactose oxidase, we have prepared a CuII complex of a methoxy‐substituted salen‐type ligand, containing a pendent indole ring on the dinitrogen chelate backbone, and characterized its one‐electron‐oxidized forms. The X‐ray crystal structures of the oxidized CuII complex exhibited the π–π stacking interaction of the indole ring mainly with one of the two phenolate moieties. The phenolate moiety in close contact with the indole moiety showed the characteristic phenoxyl radical structural features, indicating that the indole ring favors the π–π stacking interaction with the phenoxyl radical. The UV/Vis/NIR spectra of the oxidized CuII complex with the pendent indole ring was significantly different from those of the complex without the side‐chain indole ring, and the absorption and CD spectra exhibited a solvent dependence, which is in line with the phenoxyl radical–indole stacking interaction in solution. The other physicochemical results and theoretical calculations strongly support that the indole ring, as an electron donor, stabilizes the phenoxyl radical by the π–π stacking interaction.
A side-chain indole ring showed stacking interaction with the Ni(ii)-phenoxyl radical, but had smaller effects in comparison with that of the Cu(ii)-phenoxyl radical.
The wood-rot basidiomycete Ganoderma colossus has been chemically investigated. Comparative analyses of the natural fruiting body, artificially cultivated fruiting bodies, and mycelial cultures resulted in the isolation, in total, of 13 new highly modified lanostanes, ganocolossusins A−H (1−8) and ganodermalactones T−X (9−13), together with 23 known compounds (14−36). There were significant overlaps of the same compounds among the three different states of the fungal materials. Ganocolossusin D (4) displayed the most potent antimalarial activity against Plasmodium falciparum K1 (multi-drug-resistant strain) with an IC 50 value of 2.4 μM, while it was noncytotoxic to Vero cells at 50 μg/mL.
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