Formation and tuning of pillar porous-layered framework to pillar double-channelled framework

Abstract

Precise structural regulation is crucial for tailoring the functions of metal-organic frameworks (MOFs). In this work, we demonstrate that a subtle pillar-engineering strategy, which involves changing the hexafluoride anion from SiF62- to TiF62-, can trigger a dramatic topological transformation in Cu based MOFs constructed from 1,3,5 tris(2 methyl 1H imidazol 1 yl)benzene (TMBIB). The resulting frameworks, Cu TMBIB a and Cu TMBIB b, exhibit entirely different network architectures: Cu TMBIB a adopts a classical pillar-layered structure with a 3,4,5 c topology, whereas Cu TMBIB b features a rare pillar double channelled framework with an 8,12 c topology. This distinct evolution in framework architecture is hierarchically driven by the geometric and electronic disparities between the inorganic pillars, which regulate metal-node coordination and the subsequent assembly process. Notably, Cu-TMBIB-a shows good stability and favorable iodine adsorption performance. This work reveals pillar engineering as a powerful tool for MOF topology, but also expands the structural diversity of pillared frameworks, offering a rational design strategy for developing advanced separation materials.