Cage-type Structure Research Articles

General and Modular Synthesis of Covalent Organic Cages for Efficient Molecular Recognition.

Cage-type structures based on coordination and dynamic covalent chemistry have the characteristics of facile and efficient preparation but poor stability. Chemically stable organic cages, generally involving fragment coupling and multi-step reactions, are relatively difficult to synthesize. Herein, we offer a general and modular strategy to customize covalent organic cages with diverse skeletons and sizes. First, one skeleton (S) module with three extension (E) modules and three reaction (R) modules are connected by one- or two-step coupling to get the triangular monomer bearing three reaction sites. Then one-pot Friedel-Crafts condensation of the monomer and linking module of paraformaldehyde produces the designed organic cages. The cage forming could be regulated by the geometrical configuration of monomeric blocks. The S-E-R angles in the monomer is crucial; only 120° (2,4-dimethoxyphen as reaction module) or 60° (2,5-dimethoxyphen as reaction module) angle between S-E-R successfully affords the resulting cages. By the rational design of the three modules, a series of organic cages have been constructed. In addition, the host-guest properties show that the representative cages could strongly encapsulate neutral aromatic diimide guests driven by solvophobic interactions in polar solvents, giving the highest association constant of (2.58±0.18)×105 M-1.

Hybrid Silica Cage-Type Nanostructures Made from Triply Hydrophilic Block Copolymers Single Micelles.

Controlling the structure and functionality of porous silica nanoparticles has been a continuous source of innovation with important potential for advanced biomedical applications. Their synthesis, however, usually involves passive surfactants or amphiphilic copolymers that do not add value to the material after synthesis. In contrast, polyion complex (PIC) micelles based on hydrophilic block copolymers allow for the direct synthesis of intrinsically functional hybrid materials. While most previous studies have focused on bulk materials made from double-hydrophilic block copolymers (DHBC), in this work we have synthesized a triple-hydrophilic block copolymer (THBC) and demonstrated both its PIC micellization and its potential for hybrid mesoporous silica nanomaterials. Introducing this THBC has allowed to direct the transition from bulk three-dimensional (3D) materials to zero-dimensional (0D) nanomaterials with cage-type structures. The stabilization and isolation of these nanostructures formed around discrete individual micelles has been made possible by the careful design of the three different blocks that each play a key role. These nanostructures could also be synthesized from hybrid PIC micelles based on THBC-multivalent metal ions complexes, offering a direct route to metal/silica composite nanoparticles. This class of THBC polymers therefore creates significant opportunities for the synthesis of nanostructures with complex and functional architectures.

Temperature adaptability of optical middle cabin of airborne high-energy laser system based on cage-type structure

Temperature adaptability of optical middle cabin of airborne high-energy laser system based on cage-type structure

A Study of the Degradation Mechanism of Ladder-like Polyhedral Oligomeric Silsesquioxane via Fourier Transform Infrared Spectroscopy

As a result of global warming, fire outbreaks are becoming a common occurrence. There is, therefore, the need for an effective, low-cost and environmentally friendly fire-retardant material. Amine-terminated polyhedral oligomeric silsesquioxane, ATL-POSS, is a low-cost, water-soluble, fire-retardant material based on aminosilane coupling agents. Because of its solubility in water, it can serve as a general-purpose fire retardant. The ATL-POSS nanoparticles reported in this paper have high char retentions of about 75 and 54% in nitrogen and air atmospheres, respectively. Differential scanning calorimetry (DSC) was used to determine the phase transition temperatures. It was shown that ATL-POSS is an amorphous material. The thermal stability and rate of decomposition of POSS was determined by using thermogravimetric analysis (TGA). The TGA derivative curves (DTA) show that the degradation of ladder-like POSS occurred in multiple stages and that the rate of degradation is affected by the heating rate. The mechanism of decomposition of ATL-POSS was determined by using Fourier transform infrared spectroscopy, FTIR. The FTIR technique was chosen for this study because of its accessibility and ability to distinguish ladder-like POSS from the cage-type POSS structures. The FTIR spectra showed that the -Si-O-Si- cyclic structure was the predominant structure of POSS. By analyzing the FTIR spectra of the thermally treated POSS residues, obtained at the specified test temperatures, the detailed degradation mechanism of POSS was inferred. It was shown that the terminal silanol group was degraded at test temperatures below 400 °C. Silica was shown to be the final product of the pyrolysis of POSS. The presence of the FTIR transmission peaks at 1000 and 1100 cm−1, due to asymmetric vertical and horizontal stretching vibrations of the Si-O-Si, respectively, was the key evidence used to infer the ladder-like structure of POSS.

Ligand Conformation Fixation Strategy for Expanding the Structural Diversity of Copper-Tricarboxylate Frameworks and C2H2 Purification Performance Studies.

Structural and functional expansion of metal-organic frameworks (MOFs) is fundamentally important because it not only enriches the structural chemistry of MOFs but also facilitates the full exploration of their application potentials. In this work, by employing a dual-site functionalization strategy to lock the ligand conformation, we designed and synthesized a pair of biphenyl tricarboxylate ligands bearing dimethyl and dimethoxy groups and fabricated their corresponding framework compounds through coordination with copper(II) ions. Compared to the monofunctionalized version, introduction of two side groups can significantly fix the ligand conformation, and as a result, the dual-methoxy compound exhibited a different network structure from the mono-methoxy counterpart. Although only one almost orthogonal conformation was observed for the two ligands, their coordination framework compounds displayed distinct topological structures probably due to different solvothermal conditions. Significantly, with a hierarchical cage-type structure and good hydrostability, the dimethyl compound exhibited promising practical application value for industrially important C2H2 separation and purification, which was comprehensively demonstrated by equilibrium/dynamic adsorption measurements and the corresponding Clausius-Clapeyron/IAST/DFT theoretical analyses.

Thermodynamic and kinetic synergetic separation of CO2/C2H2 in an ultramicroporous metal-organic framework

The selective removal of carbon dioxide (CO2) from acetylene (C2H2) is an important separation process in the petrochemical industry, but is challenging due to the similar physicochemical properties of the two gases. Using CO2-selective adsorbents that have preferential affinity for CO2 over C2H2 in pressure swing adsorption was deemed a promising separation method for the separation of CO2/C2H2 mixtures. Herein, we report an ultramicroporous metal-organic framework, Y-bptc, to achieve efficient separation of CO2/C2H2 through thermodynamic and kinetic synergetic effects. The unique cage-type structure interconnected by small windows exhibits high adsorption capacity for CO2 while efficiently impeding adsorption diffusion of C2H2, which was proved by the single-component equilibrium and kinetic adsorption curves. Grand canonical Monte Carlo (GCMC) molecular calculations further show that the µ3-OH− of the framework have a stronger adsorption affinity for CO2 through forming hydrogen bonds. Breakthrough experiments using Y-bptc as a CO2-selective adsorbent proved that high-purity C2H2 (>99%) could be directly produced from one-step separation of CO2/C2H2 (1/1, v/v) mixtures, which greatly reduced the separation process and energy consumption. In addition, the structure of Y-bptc due to the high charge density of the Y6 cluster has high stability under humid and high-temperature conditions adding to the application possibility in industry.

Heterointerface engineering of water stable ZIF-8@ZIF-67: Adsorption of rhodamine B from water

Elimination of toxic dye, one of the utmost and usual industrial pollution released in the natural water, is the very serious issue for the modern civilization. In this study, a novel bimetallic (ZIF-8@ZIF-67) zeolitic imidazolate frameworks (ZIFs) have been fabricated by a simple and straight forward technique at room temperature. Sodalite (SOD) cage type structure, morphology and porosity of synthesized bimetallic metal-organic frameworks (MOFs) were characterized by SEM, TEM, XRD and BET. The results of characterizations showed that the ZIF-8@ZIF-67 owns greater nano crystallinity, surface area and porosity. As compared to single metallic MOFs (ZIF-67 and ZIF-8), the physical and chemical properties of ZIF-8@ZIF-67 were improved. Accordingly, the ZIF-8@ZIF-67 potentially analysed for the exclusion of rhodamine B from water and the gained outcomes were compared with the efficiency of mono-metallic MOFs (ZIF-67 and ZIF-8). Several parameters, including initial dye concentrations, sonication time, and pH on dye removal efficiency were investigated. Additionally, Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich isotherm models were used to explain the process of adsorption onto the surface of MOFs. The results disclosed that the Langmuir model sufficiently explained the adsorption procedure as monolayer with higher R2 values (R2 = 0.9924, 0.9822 and 0.9909 of ZIF-67, ZIF-8 and ZIF-8@ZIF-67 respectively). The mean free energy (E) was observed to be 0.551, 0.576 and 0.532 KJ.mol−1 for ZIF-67, ZIF-8 and ZIF-8@ZIF-67, respectively, exposing that the chemisorption dominates the process of adsorption. The qmax premeditated with Langmuir model was comparatively high (143.26 mg.g−1) as compared to ZIF-8 (56.40 mg.g−1) and ZIF-67 (81.63 mg.g−1), accrediting to the intensification in active binding sites. Further, the reusability of bimetallic MOFs was tested for four regeneration cycles and results were outstanding with only 8 ±1% decrease in efficiency. It is assumed that, the fabricated ZIF-8@ZIF-67 composite have high applicability for the adsorption of toxic dyes from water.

Three-Dimensional Fully π-Conjugated Macrocycles: When 3D-Aromatic and When 2D-Aromatic-in-3D?

Several fully π-conjugated macrocycles with puckered or cage-type structures were recently found to exhibit aromatic character according to both experiments and computations. We examine their electronic structures and put them in relation to 3D-aromatic molecules (e.g., closo-boranes) and to 2D-aromatic polycyclic aromatic hydrocarbons. Using qualitative theory combined with quantum chemical calculations, we find that the macrocycles explored hitherto should be described as 2D-aromatic with three-dimensional molecular structures (abbr. 2D-aromatic-in-3D) and not as truly 3D-aromatic. 3D-aromatic molecules have highly symmetric structures (or nearly so), leading to (at least) triply degenerate molecular orbitals, and for tetrahedral or octahedral molecules, an aromatic closed-shell electronic structure with 6n + 2 electrons. Conversely, 2D-aromatic-in-3D structures exhibit aromaticity that results from the fulfillment of Hückel’s 4n + 2 rule for each macrocyclic path, yet their π-electron counts are coincidentally 6n + 2 numbers for macrocycles with three tethers of equal lengths. It is notable that 2D-aromatic-in-3D macrocyclic cages can be aromatic with tethers of different lengths, i.e., with π-electron counts different from 6n + 2, and they are related to naphthalene. Finally, we identify tetrahedral and cubic π-conjugated molecules that fulfill the 6n + 2 rule and exhibit significant electron delocalization. Yet, their properties resemble those of analogous compounds with electron counts that differ from 6n + 2. Thus, despite the fact that these molecules show substantial π-electron delocalization, they cannot be classified as true 3D-aromatics.

From normal crosslinking to core–shell structure: Improved performance of β-cyclodextrin based adsorbent toward efficient separation of acetophenone and 1-phenylethanol

To efficiently separate acetophenone (AP) and 1-phenyethanol (PE) from petrochemical by-product, we herein report a novel feasible strategy to fabricate β-cyclodextrin (β-CD) based core–shell microsphere, which retains the cage-type crystal structure of β-CD and superior affinity to AP over PE. Using triphenylmethane-4,4′,4′'-triisocyanate (TTI) as monomer, the polymeric TTI shell can grow in-situ on the surface of β-CD particles, giving the core–shell structured CD@PTTI. The unique β-CD core and polymeric TTI shell structure was verified by a series of characterization methods. CD@PTTI-3 exhibits both high AP uptake (ca. 2.07 mmol·g−1) and AP/PE selectivity (ca. 7.2), outperforming the conventional TTI cross-linked amorphous β-CD polymer (TTI-CDP). The adsorption behavior of CD@PTTI-3 on AP and PE single-component solutions was investigated by batch adsorption experiments. Based on the experimental and theoretical results, a mechanism of competitive adsorption of AP and PE on CD@PTTI-3 involving host–guest inclusion, hydrogen bonding and π-π stacking is proposed. Furthermore, intense competition between AP and PE on CD@PTTI-3 was observed in column breakthrough experiments, and CD@PTTI-3 could purify AP from 77.16% to 93.6% by a single adsorption–desorption process.

Crystal structures and superconductivity of lithium and fluorine implanted gold hydrides under high pressures.

The investigations on gold science have been capturing research interest due to its diverse physical and chemical properties. Gold hydrides in the solid state, as a member of the Au compound family, are rare since the reaction of Au with H is hindered in terms of their similar electronegativity. It is expected that Li and F can provide electrons and holes, respectively, to help stabilize gold hydrides under high pressure. Herein, by means of a crystal structural search based on particle swarm optimization methodology accompanied by first-principles calculations, four hitherto unknown Li-Au-H compounds (i.e., LiAuH, LiAu2H, Li2Au2H, and Li6AuH) are predicted to be stable under compression. Intriguingly, Au-H bonding is found in LiAuH, LiAu2H, and Li2Au2H. As the gold content increases, Au atom arrangements exhibit diverse forms, from the chain in Li6AuH, the square layer in LiAuH, the network in Li2Au2H, and eventually to the coexistence of square and pyramid layers in LiAu2H. Additionally, Li6AuH has a unique cage-type lithium structure. Furthermore, electron-phonon coupling calculations show that these Li-Au-H phases are phonon-modulated superconductors with a superconducting critical temperature of 1.3, 0.06, and 0.02 K at 25 GPa and 2.79 K at 100 GPa. In contrast, we also identified two solid F4AuH and F6AuH phases with unexpected semiconductivity. They have structural configurations of H-bridged AuF4 quasi-square components and distorted AuF6 octahedrons, respectively, and have no gold-to-hydrogen bonds. Our current results indicate that electron doping at suitable concentrations under pressure can stabilize unique gold hydrides, and provide deep insights into the structures, electron properties, bonding behavior, and stability mechanism of ternary Li-Au-H and F-Au-H compounds.

Efficient quasi-two dimensional perovskite light-emitting diodes using a cage-type additive

High performance quasi-2D PeLEDs with maximum current efficiency of 35.5 cd A−1, by introducing α-cyclodextrin (α-CD) with a cage-type structure as an additive and TFB/PVK bilayer as a hole transport layer, are demonstrated.

X-ray crystal structures of α-cyclodextrin–5-hydroxypentanoic acid, β-cyclodextrin–5-hydroxypentanoic acid, β-cyclodextrin–ε-caprolactone, and β-cyclodextrin–ε-caprolactam inclusion complexes

Inclusion complexes of α-cyclodextrin–5-hydroxypentanoic acid (αCD-5HPA) and β-cyclodextrin–5-hydroxypentanoic acid (βCD-5HPA) were respectively prepared from aqueous solutions of cyclodextrins (CDs) and δ-valerolactone (δVL). The solutions were allowed to stand at room temperature for 1 week to give single crystals preferable for X-ray crystallography. δVL was found to be hydrolyzed in the presence of αCD or βCD to give the inclusion complexes of CDs and the hydrolysate. On the contrary, inclusion complexes of βCD–e-caprolactone (βCD–eCL) and βCD–e-caprolactam (βCD–eCLm) were respectively obtained from the aqueous solution of βCD and eCL/eCLm without hydrolysis. Packing structure of the complexes showed that αCD-5HPA forms a layer-type structure of the αCD host molecules, and that βCD-5HPA, βCD–eCL and βCD–eCLm form cage-type structures of the βCDs molecules. In these crystal structures, the guest molecules are included in the CD cavity through the hydrogen bonds or hydrophobic interactions.

Preparation and Characterization of a Modified-β-Cyclodextrin/β-Carotene Inclusion Complex and Its Application in Pickering Emulsions.

β-Cyclodextrin (β-CD) was modified using octenyl succinic anhydride (OSA) to introduce amphiphilic groups (hydrophilic carboxyl and lipophilic octenyl chains) by esterification under alkaline conditions. The FT-IR results indicated that the OSA-modified β-CD (OCD) showed new absorption peaks of an ester bond and a carboxylate (RCOO-) at 1724 and 1570 cm-1, respectively, confirming the successful preparation of OCD. Then the embedding effects of β-CD and OCD on β-carotene and the emulsifying and antioxidant properties of their inclusion complexes were evaluated. The results of XRD showed that the β-CD (or OCD)/β-carotene inclusion complexes were converted from a cage-type structure to a channel-type structure. AFM and SEM showed that the crystal characteristics and surface morphologies of the inclusion complexes were different from those of the physical mixture. The emulsion stabilized by OCD exhibited smaller droplet sizes and larger zeta-potentials than that stabilized by β-CD. In addition, the inclusion complexes-prepared emulsion exhibited lower POV values and TBARS contents than did the physical mixture. OCD/β-carotene inclusion complexes can improve the physical and oxidative stability of the emulsion, which is of great significance to the food industry.

Towards higher-Tc superconductors.

New superconductors discovered in the Akimitsu laboratory are reviewed here. These materials can be categorized into two groups:1) Cu-oxide superconductors.1-1 Cu-oxide system having CuO2 planes.1-2 Ladder lattice superconductor.2) Exploration of new metal-based superconductors.2-1 MgB2 and its application.2-2 Y2C3.2-3 Carrier-doped wide-gap semiconductors.2-4 New superconductor with a cage-type structure: R5T6Sn18 (R = Sc, Y, Lu; T = Rh, Ir).Finally, all of the new superconductors discovered in our laboratory are summarized. The outlook for the high-Tc superconductors and our present work are also described.

Tuning the Solubility of Self-Assembled Fluorescent Aromatic Cages Using Functionalized Amino Acid Building Blocks.

We previously reported novel fluorescent aromatic cages that are self-produced using a set of orthogonal dynamic covalent reactions, operating simultaneously in one-pot, to assemble up to 10 components through 12 reactions into a single cage-type structure. We now introduce N-functionalized amino acids as new building blocks that enable tuning the solubility and analysis of the resulting cages. A convenient divergent synthetic approach was developed to tether different side chains on the N-terminal of a cysteine-derived building block. Our studies show that this chemical functionalization does not prevent the subsequent self-assembly and effective formation of desired cages. While the originally described cages required 94% DMSO, the new ones bearing hydrophobic side chains were found soluble in organic solvents (up to 75% CHCl3), and those grafted with hydrophilic side chains were soluble in water (up to 75% H2O). Fluorescence studies confirmed that despite cage functionalization the aggregation-induced emission properties of those architectures are retained. Thus, this work significantly expands the range of solvents in which these self-assembled cage compounds can be generated, which in turn should enable new applications, possibly as fluorescent sensors.

Thermodynamic Insights into the Characteristics of Unary and Mixture Permeances in Microporous Membranes.

The primary objective of this article is to gain fundamental insights into the dependences of component permeances Πi in microporous membranes on the operating conditions (upstream partial pressures, temperature, and feed composition). It is argued that the permeances Πi for unary systems and mixtures need to be compared on the basis of the adsorption potential πA/RT, a convenient and practical proxy for the spreading pressure π that is calculable using the ideal adsorbed solution theory for mixture adsorption equilibrium. The use of πA/RT as a yardstick serves to elucidate and rationalize a wide variety of published experimental Πi data on unary and mixture permeances in microporous membranes. For cage-type host structures such as SAPO-34, DDR, and ZIF-8, the Πi values are uniquely dictated by the magnitude of πA/RT, irrespective of the partner species in the mixture. For MFI membranes, the tardier species slows down the more mobile partners due to correlated molecular motion within the channels; the degree of correlation is also a function of πA/RT.

A Faraday cage-type immunosensor for dual-modal detection of Vibrio parahaemolyticus by electrochemiluminescence and anodic stripping voltammetry

Vibrio parahaemolyticus (VP), as a kind of harmful bacterium to human beings, its rapid and accurate detection is particularly important. Herein, we developed a simple and efficient dual-modal Faraday cage-type immunosensor for ultrasensitive detection of VP based on electrochemiluminescence (ECL) and anodic stripping voltammetry (ASV). After being captured by capture unit on magnetic glassy carbon electrodes, VP was recognized by detector unit, achieving ECL and ASV dual-modal detection. Compared with traditional sandwich-type immunosensors, this proposed immunosensor has the advantages of significant signal amplification effects, due to its distinctive Faraday cage-type structure. Benefited from it, all Ru(bpy)22+ and AgNPs labeled on the detector unit could participate in the electrode reaction and generate stronger ECL and electrochemical signals respectively. Under the optimized conditions, the linear range was from 102 to 107 CFU mL−1 with a limit of detection (LOD) of 33 CFU mL−1, and the selectivity, stability and reproducibility were satisfactory. In addition, the results of two detection methods can mutually validate each other to avoid false positive results. Moreover, this Faraday cage-type immunosensor with dual-modal detection can also be used for detection of VP in seawater samples with recoveries in the range of 96.1–107.9%, which would be a promising tool for pathogenic bacteria analysis.

Magnetism and magnetotransport of cage-type compound UOs2Al10

We present a single-crystal study of ThOs2Al10 and UOs2Al10, crystallizing in the YbFe2Al10-type orthorhombic structure. We have performed for the first time the refinement of their cage-type crystal structure and also first-principles calculations of their electronic structures. Moreover, we carried out the magnetic, thermal and transport measurements on a single-crystalline sample of UOs2Al10. Based on the local character of the 5f2−electron configuration of the U4+ ion in UOs2Al10, the effective crystal field (CF) potential in the intermediate coupling form was estimated using the CF level scheme, composed only of singlets. The obtained scheme satisfactorily reproduces both the magnetic susceptibility (measured along the three main crystallographic directions) and the Schottky-type anomaly of the specific heat. Both these data underline the ionic character of the central atom in its cage. The latter was estimated using the specific heat data of ThOs2Al10 as a phonon reference. In addition, the strong anisotropic behavior of the Seebeck coefficient measured along the two principal directions, namely a and b axes, and the low-temperature pronounced maximum along the latter axis have been approximately explained by the CF effect. As the calculations pointed out, the latter also dominates in the S-shaped temperature dependencies of the electrical resistivity, measured using the current flowing along the three main axes. Simultaneously, the magnetoresistivity reveals a strong metallic character of UOs2Al10 and an anisotropic electronic structure reflected in the anisotropic Fermi surface that certainly originate from a c-f hybridization effect in an orthorhombic unit cell. All these give rise to the typical metallic character in a similar way as it was previously found for Fe- and Ru-bearing analogs. Moreover, the coexistence of ionic and metallic characters of all these three cage-type compounds comes from the dual behavior of the U 5f electrons. In turn, the presence of low-frequency anharmonic Einstein modes reflects the regular rattling of the U4+ ion located in the [T4Al16] cage. This rattling is, however, less apparent for UOs2Al10 than for the Fe- and Ru-based counterparts, reported in our previous papers.

One step synthesis, characterization of F127-Mn+-chlorpyrifos mesoporous silica for sustained release system with pH sensitivity

The triblock copolymer F127 (molecular formula (EO)106(PO)70(EO)106) was adopted as template with TMOS as the silica source. They were hydrolyzed by acidic aqueous solution in which chlorpyrifos (CH) and metal ions (Mn+) were introduced to the products to construct "F127-Mn+-CH" coordination structure in one step. Different sustained release systems were prepared through changing the composition of acidic aqueous solution added during the preparation. The characterization results confirmed the coordination interaction existing among metal ions, mesoporous silica and chlorpyrifos. It was also proved that the chlorpyrifos loaded in the sustained release system existed as amorphous state. According to SEM and TEM observation, the pore of the material presented as face-centered cage-type cubic structure with IM-3M symmetry similar to SBA-16 which is in accordance with N2 adsorption isotherms. The as-synthesized system showed significant pH sensitivity in the sustained release process indicating that the sustained release system can be well stored in neutral environment and activated while sprayed into earth in acid or basic environment. Their sustained release curves can be described by Korsmeyer-Peppas equation in neutral while accords with Higuchi under acid or basic environment.

Carboxylic acid Functionalized Cage-Type Mesoporous Silica FDU-12 as Support for Controlled Synthesis of Platinum Nanoparticles and Their Catalytic Applications.

Carboxylic acid functionalized 3D cage-type mesoporous silica FDU-12 with high surface area and pore volume was synthesized by a one-pot co-condensation method and used as support to synthesize Pt nanoparticles (NPs). The uniformly distributed COOH groups in the cage can control the growth of Pt NPs with high dispersion (Pt@CF-12). Pt@CF-12 was used as catalyst for the hydrolysis of ammonia borane to generate H2 and for the reduction of 4-nitrophenol to 4-aminophenol. The catalyst exhibits higher catalytic activity (H2 generation rate of 17.8 L min-1 ) and lower activation energy of 30.67 kJ mol-1 compared with other Pt-based silica catalysts due to the small size of the Pt NPs (3.5 nm) and cage-type porous structure of the support, which allowed easy diffusion of reactants. Pt@CF-12 has excellent durability, since the support prevented NP aggregation and leaching of NPs during catalysis. Pt@CF-12 can convert 93 % of 4-nitrophenol to 4-aminophenol within 10 min.