An Ionic Liquid on a Porous Organic Framework Support: A Recyclable Catalyst for the Knoevenagel Condensation in an Aqueous System.

Porous aromatic frameworks (PAFs) that feature a high density of phenyl rings in their robust frameworks are attractive platforms for catalysis because of their extremely high stability, high surface area, and adjustable pore size. In this paper, two PAF-supported ionic liquids were constructed by introducing ionic liquid units onto the framework of a PAF material PAF-111 using a series of stepwise post-synthetic modifications. The basic PAF-supported ionic liquid with a hydroxy anion exhibited high catalytic activity and high stability, and could undergo at least 10 cycles without any activity loss when catalyzing Knoevenagel condensation reaction under aqueous conditions. It is expected that our study will further promote the development of designing and applying functional PAF materials for catalysis in aqueous systems.

Facile Synthesis of Ultrastable Porous Aromatic Frameworks by Suzuki-Miyaura Coupling Reaction for Adsorption Removal of Organic Dyes.

Porous aromatic frameworks (PAFs) with robust structure, high stability, and high surface area have attracted intense interest from scientists in diverse fields. However, there are still very few reports on the adsorption of organic dyes by PAFs. In this work, four new PAFs have been facilely synthesized by the polymerization of a tetrahedral-shaped (four-node) monomer with a series of three-node monomers through Suzuki-Miyaura coupling reactions. All the obtained materials possess hierarchical porous structures and show high thermal and chemical stability. The Brunauer-Emmett-Teller (BET) surface areas of these PAFs were determined to be 857 m2 g-1 for PAF-111, 526 m2 g-1 for PAF-112A, 725 m2 g-1 for PAF-112B, and 598 m2 g-1 for PAF-113. Rhodamine B was selected as a model organic dye to test the adsorption capacities of the obtained PAF materials. PAF-111 showed a maximum adsorption capacity of 1666 mg g-1 (167 wt %) for Rhodamine B, which is among the highest values reported to date for porous organic materials. It is noteworthy that PAF-111 could be reused in at least ten cycles under the adsorption conditions without any loss of adsorption capacity. Our study has revealed the great potential and advantages of PAFs as ultrastable adsorption materials for the removal of organic dyes.

Porous aromatic framework with mesopores as a platform for a super-efficient heterogeneous Pd-based organometallic catalysis.

A strategy using a mesoporous amine-tagged porous aromatic framework (PAF70-NH2 ) to immobilize a palladium (Pd)-based molecular catalyst has been developed. The resulting immobilized catalyst PAF70-Pd, in which the framework is entirely constructed by phenyl rings linked with stable carbon-carbon bonds, has high structural rigidity and stability. Compared with the known porous organic material immobilized Pd-based catalysts, PAF70-Pd has the highest Pd content so far. Moreover, PAF70-Pd has extremely high catalytic activity with good size selectivity and very easy recyclability in catalyzing the Suzuki-Miyaura coupling reaction. In the current system, the catalyst loading could be as low as 0.001 mol% and the TOF value could go up to 28 800 h-1 which is far higher than those of the known porous organic material immobilized Pd-based catalysts. In order to elucidate the particularly high catalytic efficiency of PAF70-Pd, we prepared PAF1-Pd from PAF1-NH2 for comparison. PAF1-Pd has a higher Pd content than PAF70-Pd. However, due to the absence of large enough mesopores in PAF1-NH2 , PAF1-Pd has almost no catalytic activity under the same conditions, which definitely demonstrated that the intrinsic mesoporosity of PAF70-NH2 plays a crucial role in the superb catalytic efficiency of PAF70-Pd. This strategy to immobilize Pd-based molecular catalysts has very good expansibility to be applied in the immobilization of different organometallic catalysts into the pores of PAFs, which also has very high potential in the chemical and pharmaceutical industry.

Task-specific design of a hierarchical porous aromatic framework as an ultrastable platform for large-sized catalytic active site binding.

An amine-tagged hierarchical porous aromatic framework PAF70-NH2 with ultra-stability and narrowly distributed mesopores was synthesized. PAF70-NH2 has high potential for covalently immobilizing a relatively large-sized catalyst inside its pores. This work gave a perfect example of using PAF70-NH2 as a platform for completely recyclable heterogeneous organocatalysis.