RESUMO
The self-assembly of lanthanide ions with ditopic organic spacers results in the formation of complex tiling patterns that mimic the structural motifs of quasi-periodic 2D materials. The linking of trans-{LnI2}+ nodes (Ln = Gd, Dy) by both closed-shell and anion radicals of 4,4'-bipyridine affords rare examples of Archimedean tessellations in a metal-organic framework. We furthermore demonstrate the occurrence of sizable magnetic exchange interactions and slow relaxation of magnetization behavior in a complex tessellation pattern. The implementation of Archimedean tessellations in lanthanide(III) coordination solids couriers a strategy to design elusive quasi-periodic metal-organic frameworks with inimitable magnetic properties.
RESUMO
Five new polyketides were isolated from the rare filamentous fungus Aspergillus californicus IBT 16748 including calidiol A (1); three phthalide derivatives califuranones A1, A2, and B (2-4); and a pair of enantiomers (-)-calitetralintriol A (-5) and (+)-calitetralintriol A (+5) together with four known metabolites (6-9). The structures of the new products were established by extensive spectroscopic analyses including HRMS and 1D and 2D NMR. The absolute configurations of two diastereomers 2 and 3 and the enantiomers (-5) and (+5) were assigned by comparing their experimental and calculated ECD data, whereas the absolute configuration of 4 was proposed by analogy. Compound 1 showed moderate activity against methicillin-resistant Staphylococcus aureus.
