Versatile Postmodification of Conjugated Microporous Polymers Using Thiol-yne Chemistry

Radical thiol-yne chemistry is used for the modification of microporous networks with aliphatic alcohols. The degree of functionalization can be tuned by varying the reacted amount of thiol. Porosity analysis indicates that the microporosity can be preserved within a certain range, however, a decrease in pore size is observed

Teaching New Tricks to an Old Indicator: pH-Switchable, Photoactive Microporous Polymer Networks from Phenolphthalein with Tunable CO₂ Adsorption Power

Switchable, organic microporous networks were synthesized by Sonogashira coupling of tetrabromophenolphthalein with 1,4-diethynylenebenzene using optimized reaction conditions. The resulting networks are microporous and have specific surface areas exceeding 800 m² g^–1. The microporosity and the pore polarity are sensitive to the pH value as evidenced by nitrogen and carbon dioxide physisorption experiments. The switching between the open and closed form of the lactone ring is reversible, but some porosity is lost throughout the process. The colored, alkaline salts of these networks are photochemically active, as shown by the effective heterogeneous photosensitization of the photopolymerization of methyl methacrylate with visible light

Enhanced Carbon Dioxide Adsorption by a Mesoporous Poly(ionic liquid)

The synthesis of a mesoporous poly­(ionic liquid) network via a hard-templating pathway is presented. Structure analysis was carried out using gas adsorption, small-angle X-ray scattering, and electron microscopy. The mesoporous poly­(ionic liquid) showed a significantly faster CO₂ adsorption than its nonporous counterpart. We found the adsorption is accompanied by strong interactions, which are also reflected in a high CO₂ over N₂ selectivity

Covalent Triazine Frameworks Prepared from 1,3,5-Tricyanobenzene

A novel covalent triazine framework (CTF-0) was prepared by trimerization of 1,3,5-tricyanobenzene in molten ZnCl₂. The monomer/ZnCl₂ ratio, the reaction time, and temperature significantly influence the structure and porosity of such networks. XRD measurements revealed that crystalline frameworks can be formed with surface areas around 500 m²·g^–1 and high CO₂ uptakes. Increasing the reaction temperature yielded an amorphous material with an enlarged surface area of 2000 m²·g^–1. This material showed good catalytic activity for CO₂ cycloaddition

Hybrid Clay: A New Highly Efficient Adsorbent for Water Treatment

New hybrid clay adsorbent based on kaolinite clay and <i>Carica papaya</i> seeds with improved cation exchange capacity (CEC), rate of heavy metal ion uptake, and adsorption capacity for heavy metal ions were prepared. The CEC of the new material is ca. 75 meq/100 g in spite of the unexpectedly low surface area (≈9 m²/g). Accordingly, the average particle size of the hybrid clay adsorbent decreased from over 200 to 100 μm. The hybrid clay adsorbent is a highly efficient adsorbent for heavy metals. With an initial metal concentration of 1 mg/L, the hybrid clay adsorbent reduces the Cd²⁺, Ni²⁺, and Pb²⁺ concentration in aqueous solution to ≤4, ≤7, and ≤20 μg/L, respectively, from the first minute to over 300 min using a fixed bed containing 2 g of adsorbent and a flow rate of ≈7 mL/min. These values are (with the exception of Pb²⁺) in line with the WHO permissible limits for heavy metal ions. In a cocktail solution of Cd²⁺, and Ni²⁺, the hybrid clay shows a reduced rate of uptake but an increased adsorption capacity. The CEC data suggest that the adsorption of Pb²⁺, Cd²⁺, and Ni²⁺ on the hybrid clay adsorbent is essentially due to ion exchange. This hybrid clay adsorbent is prepared from materials that are abundant and by a simple means that is sustainable, easily recovered from aqueous solution, nonbiodegradable (unlike numerous biosorbent), and easily regenerated and is a highly efficient alternative to activated carbon for water treatment

Effective Mercury Sorption by Thiol-Laced Metal–Organic Frameworks: in Strong Acid and the Vapor Phase

Free-standing, accessible thiol (−SH) functions have been installed in robust, porous coordination networks to provide wide-ranging reactivities and properties in the solid state. The frameworks were assembled by reacting ZrCl₄ or AlCl₃ with 2,5-dimercapto-1,4-benzenedicarboxylic acid (H₂DMBD), which features the hard carboxyl and soft thiol functions. The resultant Zr-DMBD and Al-DMBD frameworks exhibit the UiO-66 and CAU-1 topologies, respectively, with the carboxyl bonded to the hard Zr­(IV) or Al­(III) center and the thiol groups decorating the pores. The thiol-laced Zr-DMBD crystals lower the Hg­(II) concentration in water below 0.01 ppm and effectively take up Hg from the vapor phase. The Zr-DMBD solid also features a nearly white photoluminescence that is distinctly quenched after Hg uptake. The carboxyl/thiol combination thus illustrates the wider applicability of the hard-and-soft strategy for functional frameworks