The removal of heavy-metal ions from wastewater has drawn intense attention, because of their toxicity, bioaccumulation tendency, and persistency in nature. Adsorption is regarded as one of the most promising methods, because of its simplicity and efficiency. In the present work, we report the preparation of a novel EDTA-functionalized covalent organic framework (COF) for the removal of heavy-metal ions. First, a COF named TpPa-NO2 was reduced to TpPa-NH2 by using Na2S2O4 as a reductant, and then EDTA dianhydride was grafted onto TpPa-NH2 to obtain TpPa-NH2@EDTA through post-modification. Both the COF morphology and structure remained unchanged after post-modification. The TpPa-NH2@EDTA showed excellent performance in adsorbing different types of heavy-metal ions, such as soft Lewis acid (Ag+, Pd2+), hard Lewis acid (Fe3+, Cr3+), and borderline Lewis acid (Cu2+, Ni2+), and the removal efficiencies are all >85% within 5 min, because of the strong chelation effect of EDTA. The TpPa-NH2@EDTA also showed high adsorption ability in a pH ≥3 environment and have an adsorption capacity of >50 mg/g for the six representative heavy-metal ions. This work provides a new idea for the application of COF materials in the removal of heavy-metal ions from wastewater.

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A novel covalent organic framework (COF) IISERP-COOH-COF1 membrane with both high water permeance and high ions rejection was developed for desalination through post-modification, which shows superior ions rejection based on size exclusion.

The preparation of functional materials from photoswitchable molecules where the molecular changes multiply to macroscopic effects presents a great challenge in material science. An attractive approach is the incorporation of the photoswitches in nanoporous, crystalline metal− organic frameworks, MOFs, often showing remote-controllable chemical and physical properties. Because of the short light-penetration depth, thin MOF films are particularly interesting, allowing the entire illumination of the material. In the present progress report, we review and discuss the status of photoswitchable MOF films. These films may serve as model systems for quantifying the isomer switching yield by infrared and UV−vis spectroscopy as well as for uptake experiments exploring the switching effects on the host−guest interaction, especially on guest adsorption and diffusion. In addition, the straightforward device integration facilitates various experiments. In this way, unique features were demonstrated, such as photoswitchable membrane separation with continuously tunable selectivity, light-switchable proton conductivity of the guests in the pores, and remote-controllable electronic conduction.

A novel photo-switchable Cu(AzDC)(4,4′-BPE)0.5 membrane was developed with the H2/CO2 separation factor being switched reversibly between 21.3 and 43.7 after irradiation with Vis light (455 nm) and UV (365 nm).