Recent progress in porous organic polymers and their application for CO_(2) capture

Carbon capture,storage,and utilization(CCSU)is recognized as an effective method to reduce the excessive emission of CO_(2).Absorption by amine aqueous solutions is considered highly efficient for CO_(2) capture from the flue gas because of the large CO_(2) capture capacity and high selectivity.However,it is often limited by the equipment corrosion and the high desorption energy consumption,and adsorption of CO_(2) using solid adsorbents has been receiving more attention in recent years due to its simplicity and high efficiency.More recently,a great number of porous organic polymers(POPs)have been designed and constructed for CO_(2) capture,and they are proven promising solid adsorbents for CO_(2) capture due to their high Brunauer-Emmett-Teller(BET)surface area(SBET),adjustable pore size and easy functionalization.In particular,they usually have rigid skeleton,permanent porosity,and good physiochemical stability.In this review,we have a detailed review for the different POPs developed in recent years,not only the design strategy,but also the special structure for CO_(2) capture.The outlook of the opportunities and challenges of the POPs is also proposed.

Boosting selective C_(2)H_(2)/CH_(4),C_(2)H_(4)/CH_(4) and CO_(2)/CH_(4) adsorption performance via 1,2,3-triazole functionalized triazine-based porous organic polymers

Nitrogen-rich porous organic polymers have shown great potentials in gas adsorption/separation,photocatalysis,electrochemistry,sensing and so on.Herein,1,2,3-triazole functionalized triazine-based porous organic polymers(TT-POPs)have been synthesized by the copper-catalyzed azide-alkyne cycloaddition(Cu-AAC)polymerization reactions of 1,3,5-tris(4-azidophenyl)-triazine with 1,4-diacetylene benzene and 1,3,5-triacetylenebenzene,respectively.The characterizations of N2 adsorption at 77 K show TTPOPs possess permanent porosity with BET surface areas of 666 m^(2)·g^(-1)(TT-POP-1)and 406 m^(2)·g^(-1)(TT-POP-2).The adsorption capacities of TT-POPs for CO_(2),CH4,C2H2 and C2H4,as well as the selective separation abilities of CO_(2)/N2,CO_(2)/CH_(4),C_(2)H_(2)/CH_(4) and C_(2)H_(4)/CH_(4) were evaluated.The gas selective separation ratio of TT-POPs was calculated by the ideal adsorbed solution theory(IAST)method,wherein the selective separation ratios of C_(2)H_(2)/CH_(4) and C_(2)H_(4)/CH_(4) of TT-POP-2 was 48.4 and 13.6(298 K,0.1 MPa),which is comparable to other adsorbents(5.6–120.6 for C_(2)H_(2)/CH_(4),10–26 for C_(2)H_(4)/CH_(4)).This work shows that the 1,2,3-triazole functionalized triazine-based porous organic polymer has a good application prospect in natural gas purification.

Polarization engineering in porous organic polymers for charge separation efficiency and its applications in photocatalytic aerobic oxidations

Photocatalytic aerobic oxidation reactions are largely governed by the efficiency of charge separation and subsequent reactive oxygen species(ROS) generation. Herein, we report a polarization engineering strategy to promote the charge separation and ROS generation efficiency by substituting the benzene unit with furan/thiophene in porous organic polymers(POPs). Benefiting from the extent of local polarization, the thiophene-containing POP(JNU-218) exhibits the best photocatalytic performance in aerobic oxidation reactions, with a yield much higher than those for the furan-containing POP(JNU-217) and the benzenecontaining POP(JNU-216). Experimental studies and theoretical calculations reveal that the increase of local polarization can indeed reduce the exciton binding energy, and therefore facilitate the separation of electron-hole pairs. This work demonstrates a viable strategy to tune charge separation and ROS generation efficiency by modulating the dipole moments of the building blocks in porous polymeric organic semiconductors.

(Catecholate)Cu^(I)_(2)-Displayed Porous Organic Polymers as Efficient Heterogeneous Catalysts for the Mild and Selective Aerobic Oxidation of Alcohols

Porous organic polymers(POPs)containing catalytically active sites are of paramount importance for heterogeneous catalysis.However,the catalytically active sites of reported POPs are mostly limited to mononuclear metal species.Herein,we report the reaction between catechol-containing POPs(Cat-POPs)and[CuIMes]n to afford the corresponding Cu^(I)_(2)-CatPOPs with a putative vicinal binuclear(catecholate)Cu^(I)_(2)moiety.The resulting Cu^(I)_(2)-CatPOPs exhibit high Brunauer–Emmett–Teller surface areas,good stability,and excellent catalytic activity toward the aerobic oxidation of a broad range of primary and secondary alcohols under mild conditions,with either 2,2,6,6-tetramethylpiperidinyl-N-oxyl or 9-azabicyclo[3.3.0]nonane-N-oxyl as the cocatalyst.As green aerobic oxidation catalysts,the Cu^(I)_(2)-CatPOPs are much more active than the correspondingmononuclear CuIICatPOPs,where each catecholate moiety only supports one CuII center;CuI-ConPOPs,where the binding sites for CuI is a nonvicinal 1,4-dihydroxybenzene moiety;and the homogeneous analogue(3,6-di-tert-butyl catecholate)Cu^(I)_(2).These results are consistent with a proposed vicinal binuclear Cu^(I)_(2)structure that can efficiently activate molecular oxygen for the aerobic oxidation of alcohols,mechanistically similar to that observed in dicopper-containing oxygenases.Our results demonstrate the facile preparation of POPs with binuclear catalytically active sites that function as green heterogeneous catalysts for efficient oxidation of alcohols.

Pyrylium-based porous organic polymers via Knoevenagel condensation for efficient visible-light-driven heterogeneous photodegradation

Pyrylium salts are a type of representative and convincing example of versatility and variety not only as a nodal point in organic transformations but also as an attractive building block in functional organic materials. Herein, we report an effective synthetic protocol to fabricate a new pyrylium-containing porous organic polymers(POPs), named TMP-P, via Knoevenagel condensation with 2,4,6-trimethylpyrylium salt(TMP) as the key building block and 1,4-phthalaldehyde as the linker. The resulting ionic polymer TMPP exhibited efficient visible-light-driven heterogeneous photodegradation of Rhodamine B, owing to the presence of wide visible light absorption and a narrow optical band gap triggered pyrylium core in the framework.

Engineering porous organic polymers for carbon dioxide capture

As atmospheric CO_2 levels rise, the development of physical or chemical adsorbents for CO_2 capture and separation is of great importance on the way towards a sustainable low-carbon future. Porous organic polymers are promising candidates for CO_2 capture materials owing to their structural flexibility, high surface area, and high stability. In this review, we highlight high-performance porous organic polymers for CO_2 capture and summarize the strategies to enhance CO_2 uptake and selectivity, such as increasing surface area, increasing interaction between porous organic polymers and CO_2, and pore surface functionalization.

Potential applications of porous organic polymers as adsorbent for the adsorption of volatile organic compounds

Volatile organic compounds(VOCs)with high toxicity and carcinogenicity are emitted from kinds of industries,which endanger human health and the environment.Adsorption is a promising method for the treatment of VOCs due to its low cost and high efficiency.In recent years,activated carbons,zeolites,and mesoporous materials are widely used to remove VOCs because of their high specific surface area and abundant porosity.However,the hydrophilic nature and low desorption rate of those materials limit their commercial application.Furthermore,the adsorption capacities of VOCs still need to be improved.Porous organic polymers(POPs)with extremely high porosity,structural diversity,and hydrophobic have been considered as one of the most promising candidates for VOCs adsorption.This review generalized the superiority of POPs for VOCs adsorption compared to other porous materials and summarized the studies of VOCs adsorption on different types of POPs.Moreover,the mechanism of competitive adsorption between water and VOCs on the POPs was discussed.Finally,a concise outlook for utilizing POPs for VOCs adsorption was discussed,noting areas in which further work is needed to develop the next-generation POPs for practical applications.

Hollow click-based porous organic polymers for heterogenization of [Ru（bpy）3]2＋ through electrostatic interactions

A facile approach for the heterogenization of transition metal catalysts using non-covalent interactions in hollow click-based porous organic polymers （H-CPPs） is presented. A catalytically active cationic species, [Ru（bpy）3]〉 （bpy = 2,2＇-bipyridyl）, was immobilized in H-CPPs via electrostatic interactions. The intrinsic properties of [Ru（bpy）3]〉 were well retained. The resulting Ru- containing hollow polymers exhibited excellent catalytic activity, enhanced stability, and good recyclability when used for the oxidative hydroxylation of 4-methoxyphenylboronic acid to 4-methoxyphenol under visible-light irradiation. The attractive catalytic performance mainly resulted from efficient mass transfer and the maintenance of the chemical properties of the cationic Ru complex in the H-CPPs.

Water-dispersible and soluble porous organic polymers for biomedical applications

Porous organic polymers(POPs)have become an emerging class of advanced porous organic materials owing to their structural diversity and tailored functions in solid state and organic media.Creating water-soluble and related water-dispersible POPs is still very challenging in the research area of porous organic materials.Their porosity-based functions with diverse topological architectures in aqueous media offer promising platforms in bio-related fields.This review highlights recent progress on water soluble or dispersible POPs for biomedical applications including bioimaging and biosensing,nanocarriers for drug delivery and tumor targeting,phototherapeutics,protein and gene delivery,biomacromolecule encapsulation and discrimination,and anti-microbial activity.

Metallocorrole-based porous organic polymers as a heterogeneous catalytic nanoplatform for efficient carbon dioxide conversion

Metallocorrole macrocycles that represent a burgeoning class of attractive metal-complexes from the porphyrinoid family,have attracted great interest in recent years owing to their unique structure and excellent performance revealed in many fields,yet further functionalization through incorporating these motifs into porous nanomaterials employing the bottom-up approach is still scarce and remains synthetically challenging.Here,we report the targeted synthesis of porous organic polymers(POPs)constructed from custom-designed Mn and Fe-corrole complex building units,respectively denoted as CorPOP-1(Mn)and CorPOP-1(FeCl).Specifically,the robust CorPOP-1(Mn)bearing Mn-corrole active centers displays superior heterogeneous catalytic activity toward solvent-free cycloaddition of carbon dioxide(CO_(2))with epoxides to form cyclic carbonates under mild reaction conditions as compared with the homogeneous counterpart.CorPOP-1(Mn)can be easily recycled and does not show significant loss of reactivity after seven successive cycles.This work highlights the potential of metallocorrole-based porous solid catalysts for targeting CO_(2) transformations,and would provide a guide for the task-specific development of more corrole-based multifunctional materials for extended applications.

Construction of Ionic Porous Organic Polymers(iPOPs)via Pyrylium Mediated Transformation

Two new ionic porous organic polymers(iPOPs)with different counter anions were successfully fabricated via well-known pyrylium mediated transformation into pyridinium.13C solid-state NMR,XPS,and FTIR were analyzed and confirmed the formation of pyridinium in the network.Containing charged and aromatic networks,both iPOPs exhibit a high affinity towards toxic hexavalent chromium Cr(Ⅵ)ions.What is more,it has been demonstrated that both CO2 adsorption and Cr(Ⅵ)removal properties can be tuned by simply varying counter anions.

Ultrathin polyamide nanofiltration membrane prepared by triazine-based porous organic polymer as interlayer for dye removal

Separation membrane with high flux is generally encouraged in industrial application,because of the tremendous needs for decreasing membrane areas,usage costs and space requirements.The most effective and direct method for obtaining the high flux is to decrease membrane thickness.Polyamide(PA)nanofiltration membrane is conventionally prepared by the direct interfacial polymerization(IP)on substrate surface,and results in a thick PA layer.In this work,we proposed a strategy that constructing triazine-based porous organic polymer(TRZ-POP)as the interlayer to prepare the ultrathin PA nanofiltration membranes.TRZ-POP is firstly deposited on the polyethersulfone substrate,and then the formed TRZ-POP provides more adhesion sites towards PA based on its high specific surface areas.The chemical bonding between terminal amine group of TRZ-POP and the amide group of PA further improves the binding force,and strengthens the stability of PA layer.More importantly,the high porosity of TRZPOP layer causes the higher polymerization of initial PA owning to the stored sufficient amino monomer;and H-bonding interaction between amine groups of TRZ-POP and piperazine(PIP)can astrict the release of PIP.Thus,IP process is controlled,and the thinnest thickness of prepared PA layer is only<15 nm.As expected,PA/TRZ-POP membrane shows a more excellent water flux of 1414 L·m^(-2)·h^(-1)·MPa^(-1)than that of the state-of-the-art nanofiltration membranes,and without sacrificing dye rejection.The build of TRZPOP interlayer develops a new method for obtaining a high-flux nanofiltration membrane.

In-situ self-templating synthesis of 3D hierarchical porous carbonsfrom oxygen-bridged porous organic polymers for highperformance supercapacitors

It is a big challenge to well control the porous structure of carbon materials for supercapacitor application.Herein,a simple in-situ self-templating strategy is developed to prepare three-dimensional(3D)hierarchical porous carbons with good combination of micro and meso-porous architecture derived from a new oxygen-bridged porous organic polymer(OPOP).The OPOP is produced by the condensation polymerization of cyanuric chloride and hydroquinone in NaOH ethanol solution and NaCl is in-situ formed as by-product that will serve as template to construct an interconnected 3D hierarchical porous architecture upon carbonization.The large interface pore architecture,and rich doping of N and O heteroatoms effectively promote the electrolyte accessibility and electronic conductivity,and provide abundant active sites for energy storage.Consequently,the supercapacitors based on the optimized OPOP-800 sample display an energy density of 8.44 and 27.28 Wh·kg^(−1)in 6.0 M KOH and 1.0 M Na2SO4 electrolytes,respectively.The capacitance retention is more than 94%after 10,000 cycles.Furthermore,density functional theory(DFT)calculations have been employed to unveil the charge storage mechanism in the OPOP-800.The results presented in this job are inspiring in finely tuning the porous structure to optimize the supercapacitive performance of carbon materials.

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.

Synthesis and Properties of Porous Organic Polymers from a Rigid Macrocyclic Building Block

Two rigid macrocyclic CTV-based porous organic polymers, Click-POP-1 and Click-POP-2, have been synthe- sized by Click reaction of a cyclotriveratrylene analogue with alkyne groups and aromatic azides in one pot. FTIR, solid 13C NMR and elemental analysis confirmed the formation of the polymers. Both of them possess high thermo-stability which is up to 410 and 900 ℃, respectively, and moderate hydrogen storage properties with 0.46 wt% at 77 K. Their nitrogen uptake showed type-I isotherm with BET surface areas up to 342 and 317 m2·g ^-1.

Insertion of pillar[5]arene into Troger’s base-derived porous organic polymer for promoted heterogeneous catalytic performance in Knoevenagel condensation and CO_(2)fixation

Development of new metal-free heterogeneous catalysts has long been the focus of intense research interest.The integration of multifunctional monomers into the skeletons of porous organic polymers(POPs)provides an efficient pathway to achieve this goal.Herein,we rationally designed and successfully prepared a new Troger’s base(TB)-derived POPs by insertion of pillar[5]arene macrocycle as a positively auxiliary group.Combined the both merits of pillar[5]arene macrocycle and TB moiety,the as-prepared polymer was further explored as an effective metal-free heterogeneous catalyst and exhibited promoted catalytic performance in Knoevenagel condensation and CO_(2)conversion.This work provides a new strategy to fabricate metal-free heterogeneous catalysts based on macrocyclic POPs.

Nitrogen-rich isoindoline-based porous polymer: Promoting knoevenagel reaction at room temperature

Nitrogen-rich porous organic polymers(POPs)with basic features have already shown promising performance in various organic reactions.But the harsh conditions,tedious synthetic methods and the requirement of specific monomers impede their further application.Herein,we introduce isoindoline chemistry into POP community.An isoindoline formation process between aniline and bromomethylbenzenedcoupling nucleophilic substitution,HBr elimination,and intramolecular cyclization in one pot,is utilized for POPs synthesis.Nitrogen-rich isoindolinebased porous polymers(IPPs)were obtained with specific surface areas up to 408 m^(2) g^(-1).Unexpectedly,mechanochemistry could enable the rapid(3 h)and solid-state synthesis of IPP catalysts.Moreover,this nitrogen-rich catalyst presents excellent activity(isolated yield:99%),scalable ability(up to 14 g per run)and recyclability(five runs)towards the Knoevenagel condensation reaction under mild reaction conditions(water as solvent at room temperature).

Ru complex and N,P-containing polymers confined within mesoporous hollow carbon spheres for hydrogenation of CO_(2)to formate

The development of reliable catalysts with both excellent activity and recyclability for carbon dioxide(CO_(2))hydrogenation is challenging.Herein,a ternary hybrid heterogeneous catalyst,involving mononuclear Ru complex,N,P-containing porous organic polymers(POPs),and mesoporous hollow carbon spheres(Ru^(3+)-POPs@MHCS)is reported for CO_(2)hydrogenation to formate.Based on comprehensive structural analyses,we demonstrated that Ru^(3+)-POPs were successfully immobilized within MHCS.The optimized Ru^(3+)-0.5POPs@MHCS catalyst,which was obtained with about 5 wt.%Ru^(3+)and 0.5 mmol POPs polymers confined into 0.3 g MHCS,exhibited high catalytic activity for CO_(2)hydrogenation to formate(turnover number(TON)>1,200 for 24 h under mild reaction conditions(4.0 MPa,120℃))and improved durability,compared to Ru^(3+)catalysts without POPs polymers(Ru^(3+)-MHCS)and unencapsulated MHCS(Ru^(3+)-0.5POPs)catalysts.The improved catalytic performance is attributed to the high surface area and large pore volume of MHCS which favors dispersion and stabilization of Ru^(3+)-POPs.Furthermore,the MHCS and POPs showed high CO_(2)adsorption ability.Ru^(3+)-POPs encapsulated into MHCS reduces the activation energy barrier for CO_(2)hydrogenation to formate.

A Three-Dimensional Silicon-Diacetylene Porous Organic Radical Polymer

Radical-containing porous organic polymers(POPs)have drawn great interest in various applications.However,the synthesis of radical POPs remains challenging due to the unstable nature of organic radicals.Here,a persistent and stable three-dimensional silicon-diacetylene porous organic radical polymer was synthesized via a classic Eglinton homocoupling reaction of tetraethynylsilane.The presence of carbon radicals in this material was confirmed by electron paramagnetic resonance,and its paramagnetic behavior was analyzed by a superconducting quantum interference device.This unique material has a low-lying lowest unoccupied molecular orbital(LUMO)energy level(−5.47 eV)and a small energy gap(ca.1.46 eV),which shows long-term cycling stability and excellent rate capability as an anode material for lithium-ion batteries,demonstrating potential application in energy fields.

Thiophene-based conjugated microporous polymers:synthesis,characterization and efficient gas storage

A series of thiophene-based conjugated microporous polymers(ThPOPs) have been synthesized on the basis of ferric chloride-catalyzed oxidative coupling polymerization of multi-thienyl monomers. The structures of ThPOPs were confirmed via solid-state 13 C CP/MAS NMR spectroscopy and Fourier-transform infrared spectroscopy. The ThPOPs possess high porosities and their high Brunauer-Emmett-Teller specific surface area results vary between 350 and 1320 m^2 g^(-1). The presence of abundant ultra-micropores at 0.50–0.63 nm allows ThPOPs efficient gas(carbon dioxide, methane, and hydrogen) adsorption.