Rational design of new in situ reduction of Ni(II)catalytic system for low-cost and large-scale preparation of porous aromatic frameworks

Porous aromatic framework 1(PAF-1)is an extremely representative nanoporous organic framework owing to its high stability and exceptionally high surface area.Currently,the synthesis of PAF-1 is catalyzed by the Ni(COD)2/COD/bpy system,suffering from great instability and high cost.Herein,we developed an in situ reduction of the Ni(II)catalytic system to synthesize PAF-1 in low cost and high yield.The active Ni(0)species produced from the NiCl_(2)/bpy/NaI/Mg catalyst system can effectively catalyze homocoupling of tetrakis(4-bromophenyl)methane at the room temperature to form PAF-1 with high Brunauer-Emmett-Teller(BET)-specific surface area up to 4948 m^(2) g^(−1)(Langmuir surface area,6785 m2 g−1).The possible halogen exchange and dehalogenation coupling mechanisms for this new catalytic process in PAF's synthesis are discussed in detail.The efficiency and universality of this innovative catalyst system have also been demonstrated in other PAFs'synthesis.This work provides a cheap,facile,and efficient method for scalable synthesis of PAFs and explores their application for high-pressure storage of Xe and Kr.

Frustrated Lewis pairs in situ formation in B-based porous aromatic frameworks for efficient o-phenylenediamine cyclization

Benzimidazoles are very important chemical materials in the pharmaceutical industry,and the most common synthetic route is cyclization of o-phenylenediamine with carbon sources,in which utilization of inexpensive and abundant CO_(2)as C1 source is very impressive.Porous aromatic frameworks(PAFs)with highly desired skeletons have attracted great attentions in gas capture and catalysis.Herein,B-based PAF-165 and PAF-166 are designed and synthesized via Friedel-Crafts alkylation reaction,which present high surface areas as well as high stability.Benefiting from the abundant electron-deficient B centers,both PAFs exhibit excellent selective CO_(2)adsorption abilities.The presence of sterically hindered B units in PAFs can act as Lewis acid active sites for the frustrated Lewis pairs(FLPs)in situ formation with ophenylenediamine,thus promoting the synthesis of benzimidazole.The optimal reaction conditions for o-phenylenediamine cyclization with PAF catalysts are explored,and the reaction mechanism is also proposed.This work provides feasible ideas for incorporating FLPs within porous materials as reusable heterogeneous catalysts for CO_(2)capture and conversion.

A step‐growth strategy to grow vertical porous aromatic framework nanosheets on graphene oxide:Hybrid material‐confined Co for ammonia borane methanolysis

The rational synthesis of a two-dimensional(2D)porous aromatic framework(PAF)with a controllable growth direction remains a challenge to overcome the limitation of traditional stacked 2D materials.Herein,a step-growth strategy is developed to fabricate a vertically oriented nitrogen-rich porous aromatic framework on graphene oxide(V-PAF-GO)using monolayer benzidine-functionalized GO(BZ-GO)as a molecular pillar.Then,the confined Co nanoparticle(NP)catalysts are synthesized by encapsulating ultra-small Co into the slit pores of V-PAF-GO.Due to the high nitrogen content,large specific surface area,and adequate slit pores,the optimized vertical nanocomposites V-PAF-GO provide abundant anchoring sites for metal NPs,leading to ultrafine Co NPs(1.4 nm).The resultant Co/V-PAF-GO catalyst shows an extraordinary catalytic activity for ammonia borane(AB)methanolysis,yielding a turnover frequency value of 47.6 min−1 at 25°C,comparable to the most effective non-noble-metal catalysts ever reported for AB methanolysis.Experimental and density functional theory studies demonstrate that the electron-donating effect of N species of PAF positively corresponds to the low barrier in methanol molecule activation,and the cleavage of the O–H bond in CH3OH has been proven to be the rate-determining step for AB methanolysis.This work presents a versatile step-growth strategy to prepare a vertically oriented PAF on GO to solve the stacking problem of 2D materials,which will be used to fabricate other novel 2D or 2D–2D materials with controllable orientation for various applications.

High energy and insensitive explosives based on energetic porous aromatic frameworks

The design and synthesis of energetic materials with a compatibility of high energy and insensitivity have always been the research fronts in military and civilian fields.Considering excellent performances of porous organic frameworks and the lack of research in the field of energetic materials,in this study,a new concept named energetic porous aromatic frameworks(EPAFs)is proposed.The strategy of coating high energy explosives such as 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20)and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX)in the EPAFs by wet-infiltration method has successfully realized the assembly of target energetic composite materials.The results show that the 75 wt.%CL-20@EPAF-1 possesses the safer impact sensitivity of 31.4 J than that of CL-20(4.0 J).Notably,for 75 wt.%CL-20@EPAF-1,in addition to the superior detonation performances of the detonation velocity(8,761 m·s^(-1))and detonation pressure(31.27 GPa),the synergistic effect of the nitrogen-rich EPAFs and the nitramines high energy explosives results in a higher heat of detonation that surpasses the most of pristine high explosives and reported novel energetic materials.In prospect,energetic porous aromatic frameworks could be a promising and inspiring strategy to build high energy insensitive energetic materials.

Targeted synthesis of novel porous aromatic frameworks with selective separation of CO_2/CH_4and CO_2/N_2

Novel porous aromatic frameworks（PAF-53 and PAF-54） have been obtained by the polymerization of amino compound（p-phenylenediamine and melamine） and cyanuric chloride. They display a certain amount of CO2 adsorption capacity and highly selective separation of CO2/CH4 and CO2/N2 as 18.1 and83 by Henry Law respectively. They may be applied as ideal adsorbents to separate and capture CO2.

Silver-anchored porous aromatic framework for efficient conversion of propargylic alcohols with CO_(2) at ambient pressure

The conversion of propargylic alcohols and carbon dioxide(CO_(2)) into fine chemicals suffers from issues of harsh reaction conditions and difficult catalyst recovery. To achieve efficient CO_(2)activation at low energy consumption, a silver-anchored porous aromatic framework catalyst Ag@PAF-DAB with high active phase density and CO_(2)adsorption capacity was proposed. Since Ag@PAF-DAB has the dual functions of CO_(2)capture and conversion, propargylic alcohols were completely converted into α-alkylidene cyclic carbonate or α–hydroxy ketone as high value-added product under atmospheric pressure(CO_(2), 0.1 MPa) and low silver equivalent(0.5 mol%). Notably, Ag@PAF-DAB exhibited broad substrate diversity, high stability,and excellent reusability. By applying FTIR and GC, the key to green synthetic route of α–hydroxy ketone was confirmed to lie in the further hydration of α-alkylidene cyclic carbonate.

Synthesis of porous aromatic framework with Friedel–Crafts alkylation reaction for CO_2 separation

A novel porous aromatic framework, PAF-8, derived from tetraphenylsilane as basic building unit, was successfully synthesized via Friedel-Crafts alkylation reaction. This PAF material had high thermal stability as well as high surface area （785 m^2 g^-1） calculated from the Brunauer-Emmett-Teller （BET） model. Meanwhile, PAF-8 possessed high performances in gas sorption and especially for CO2 separation.

Novel Porous Aromatic Framework with Excellent Separation Capability of CO2 in N2 or CH4

A novel porous aromatic framework, PAF-52, was obtained via the polymerization of tetrahedral mono- mer tetrakis（4-cyanodiphenyl） methane（TCDPM） with the aid of a facile ionothermal method. PAF-52 has a surface area of 1159 m2/g（BET）, and shows a considerable high separation ability of CO2 in N2 or CH4 respectively at room temperature, using gas-chromatography experiments as evidence,

具有亚纳米通道的多孔芳香骨架膜的合成及其快速选择性脱盐性能研究

薄膜中自由传输水通道的建立对高效脱盐至关重要,然而靶向合成具有这种传输通道的薄膜材料非常具有挑战性.本研究利用分子设计策略,合成了具有刚性和开放结构的多孔芳香骨架(PAF)膜,以达到调控水传输过程的目的.具有三角形结构的腈基单体在三氟甲磺酸的催化下形成了PAF-98系列膜材料.采用刚性和特定几何形状的单体所合成的膜材料具有4.5-6.7Å的孔道,能够有效分离水分子(2.8Å)和钠盐离子(7.2Å).同时,合成的PAF膜具有很好的柔软性和连续性,是一种理想的海水淡化膜.反渗透实验表明,三种PAF膜对水分子都具有选择性透过的能力,其中PAF-98-E膜具有优异的脱盐效果:水通量为547.1 L m^(-2)h^(-1),钠盐离子的截留率为90%,该性能优于现有报道的膜材料.此外,PAF-98-E膜还能够高效去除实际海水中各种阳离子,在海水淡化中具有广阔的应用前景.