Spatial distribution modulation of mixed building blocks in metal-organic frameworks.

The placement of mixed building blocks at precise locations in metal-organic frameworks is critical to creating pore environments suitable for advanced applications. Here we show that the spatial distribution of mixed building blocks in metal-organic frameworks can be modulated by exploiting the different temperature sensitivities of the diffusion coefficients and exchange rate constants of the building blocks. By tuning the reaction temperature of the forward linker exchange from one metal-organic framework to another isoreticular metal-organic framework, core-shell microstructural and uniform microstructural metal-organic frameworks are obtained. The strategy can be extended to the fabrication of inverted core-shell microstructures and multi-shell microstructures and applied for the modulation of the spatial distribution of framework metal ions during the post-synthetic metal exchange process of a Zn-based metal-organic framework to an isostructural Ni-based metal-organic framework.