SummaryA systematic approach has been employed to obtain a hydrolytically stable cationic metal-organic framework (MOF). The synthesized two-dimensional Ni(II)-centered cationic MOF, having its backbone built from purely neutral N-donor ligand, is found to exhibit uncommon resistance over wide pH range, particularly even under highly alkaline conditions. This report presents a rare case of a porous MOF retaining structural integrity under basic conditions, and an even rarer case of a porous cationic MOF. The features of stability and porosity in this ionic MOF have been harnessed for the function of charge- and size-selective capture of small organic dye through ion-exchange process across a wide pH range.

The understanding of structure–property and structure–stability correlation has become an important facet of material development in the domain of metal–organic frameworks (MOFs). Owing to the paucity of stable compounds, the progress of constructing MOFs out of neutral linkers that exhibit remarkable promise has largely been stalled. To understand the influence of anions in affording structure features, properties, and stability in such MOFs, a series of MOFs constructed from same metal cation and ligand have been synthesized and examined. Further ascribing a structure–property correlation, the stable MOFs obtained in this work have been applied for sensing and capture of the radioactive pertechnetate anion TcO4 –, via surrogate anions MnO4 – and ReO4 –, and capture of the greenhouse gas CO2. Notably, the sensing of such toxic anions has been rarely been explored using porous crystalline solids.

An isostructural pair of extremely rare, permanently microporous sulfonate-based metal−organic frameworks (MOFs) having a novel topology has been reported here by integration of rationally chosen building units. The compounds bear polar sites in the pore surfaces and exhibit selective adsorption of CO 2 , which features among the highest reported uptakes in the domain of organosulfonate-based MOFs. The compounds also exhibit multifunctionality for C 6 -cyclic hydrocarbon separation and selective detection of neurotransmitter nitric oxide. Such multifunctional behavior on the basis of permanent porosity has been rarely observed for sulfonate-based MOFs. The efficacy of the synthesis approach is further highlighted by the resistance over a wide pH range and promising feasibility of reticular chemistry in porous organosulfonate-based systems.

Two rationally designed MOFs were reported for the luminescent detection of toxic allyl alcohol selectively over other small alcohols.