RESUMO
Biological macromolecules exhibit emergent functions through hierarchical self-assembly, a concept that is extended to design artificial supramolecular assemblies. Here, the first example of breaking the common parallel arrangement of capsule-shaped zirconium coordination cages is reported by constructing the hierarchical porous framework ZrR-1. ZrR-1 adopts a quaternary structure resembling protein and contains 12-connected chloride clusters, representing the highest connectivity for zirconium-based cages reported thus far. Compared to the parallel framework ZrR-2, ZrR-1 demonstrated enhanced stability in acidic aqueous solutions and a tenfold increase in BET surface area (879 m2 g-1 ). ZrR-1 also exhibits excellent proton conductivity, reaching 1.31 × 10-2 S·cm-1 at 353 K and 98% relative humidity, with a low activation energy of 0.143 eV. This finding provides insights into controlling the hierarchical self-assembly of metal-organic cages to discover superstructures with emergent properties.
RESUMO
Fluorescent agents play an important role in the peroxyoxalate chemiluminescence system. However, the effect of different frameworks on chemiluminescence (CL) has not been explored. Herein two pyrene-based metal-organic frameworks (MOFs), [Pb2L]n·2nDMA·2nH2O (1) and [(Ca2L)·(DMF)3]n·2.5nDMF·6nH2O (2) (H4L = 5,5'-(-pyrene-1,6-diyl)-diisophthalic acid; DMA = N,N'-dimethylacetamide; DMF = N,N'-dimethylformamide), have been successfully synthesized and are applied to CL. They both exhibit strong and lasting emission that is visible to the naked eye and is significantly stronger than that of the ligand. More importantly, compared with 2, 1 has notably better CL performance. We infer that the reason may be that 1 has higher stability and larger open channels, which can avoid the aggregation of organic ligands as well as provide an effective pathway for the active substance to diffuse into the channels.
