Metal-organic Structures Research Articles

Molecularly Woven Cationic Covalent Organic Frameworks for Highly Selective Electrocatalytic Conversion of CO2 to CO.

Coupling carbon capture with electrocatalytic carbon dioxide reduction (CO2R) to yield high-value chemicals presents an appealing avenue for combating climate change, yet achieving highly selective electrocatalysts remains a significant challenge. Herein, two molecularly woven covalent organic frameworks (COFs) are designed, namely CuCOF and CuCOF+, with copper(I)-bisphenanthroline complexes as building blocks. The metal-organic helical structure unit made the CuCOF and CuCOF+ present woven patterns, and their ordered pore structures and cationic properties enhanced their CO2 adsorption and good conductivity, which is confirmed by gas adsorption and electrochemical analysis. In the electrocatalytic CO2R measurements, CuCOF+ decorated with extra ethyl groups exhibit a main CO product with selectivity of 57.81%, outperforming the CuCOF with 42.92% CO at the same applied potential of 0.8 VRHE. After loading Pd nanoparticles, CuCOF-Pd and CuCOF+-Pd performed increased CO selectivity up to 84.97% and 95.45%, respectively. Combining the DFT theoretical calculations and experimental measurements, it is assumed that the molecularly woven cationic COF provides a catalytic microenvironment for CO2R and ensures efficient charge transfer from the electrode to the catalytic center, thereby achieving high electrocatalytic activity and selectivity. The present work significantly advances the practice of cationic COFs in real-time CO2 capture and highly selective conversion to value-added chemicals.

Intelligent marine waterborne epoxy coating based on functionalized multiscale nanocomposite: mechanical enhancement, self-reporting, and active/passive anti-corrosion

Corrosion activities and related accidents are significant issues for marine facilities, leading to considerable economic losses. Waterborne epoxy (EP) coating has been seen as one of the optimal options for corrosion protection due to its stable properties and eco-friendliness (0 g/L volatile organic compounds). Nevertheless, several intrinsic deficiencies require improvement, such as fragile mechanical properties and defects (macro and micro), resulting in the continuous deterioration of comprehensive coating performances. In this work, a novel nanocomposite coating with mechanical enhancement, intelligent self-reporting, and active protection is fabricated by integrating the functionalized and compatible graphene oxide/cerium based metal-organic framework multiscale structure (GO-CeMOF-P/M). Notably, the homogenous dispersion of GO-CeMOF-P/M and its chemical interaction with the polymer matrix effectively reduces the defects resulting from solution volatilizing and enhances the compactness, which boosts the tensile strength (32.1 MPa/8.5%) and dry adhesion force (5.8 MPa) of the coating. Additionally, the controllable responsiveness and release of multiscale nanocomposite within external environments endow intelligent active protection and self-reporting characteristics for the GO-CeMOF-P/M-EP coating, making it especially suitable for a variety of practical marine applications. Furthermore, following immersion of 80 d in the aggressive environment, Zf=0.01 Hz value of GO-CeMOF-P/M-EP coating is 1.2 × 1010 Ω·cm2, which is 164.4 times larger than that of EP coating (7.3 × 107 Ω·cm2), demonstrating remarkably strengthened anti-corrosion ability. Consequently, by offering an intriguing design strategy, the current work anticipates addressing the inherent deficiencies of EP coating and facilitating its practicality and feasibility in real sea environments.

Engineering of dopamine conjugated with bovine serum albumin and zeolite imidazole framework: A promising drug delivery nanocarrier on lung cancer cells

Modern, highly abundant materials called metal-organic structures (MOF) comprise metal ions and organic coordinating molecules and have attracted attention as potential biomedical materials due to their unusual properties. In the present study, the anticancer drug sorafenib (SF) and the Kaempferol (KM) were encapsulated in a nanocomposite made of bovine serum albumin (BA) as the core and pH-dependent zeolitic imidazolate framework-8 (ZIF) coating. To develop a multifunctional nanocarrier, polydopamine, Au3+ chelation, and gallic acid (GL) conjugation were used to build BA@SF@ZIF and BA@SF@ZIF/KM. A variety of characterisation techniques verified the success of the nanocarrier's fabrication. Studies in vitro exhibited that BA@SF@ZIF/DA/GL and BA@SF@ZIF/KM/DA/GL released their respective ligands in a pH-dependent manner due to ZIF-8. These nanocarriers' cytotoxicity and apoptotic effects were measured with the MTT evaluation. Morphological and nuclear damage staining in A549 and H1299 human lung cancer cells. The cytotoxicity investigation displayed that BA@SF@ZIF/DA/GL and BA@SF@ZIF/KM/DA/GL were more efficient than free sorafenib in A549 and H1299 cells with less toxicity in HUVECs. The DNA fragmentation of the cells was assessed by utilizing the comet assay. BA@SF@ZIF/KM/DA/GL increased ROS levels and caused mitochondrial membrane potential and DNA damage, which resulted in apoptosis. Therefore, we believe the developed smart BA@SF@ZIF/KM/DA/GL could be a promising therapeutic approach using sorafenib for lung cancer therapy.

Matrimid/MOP-18 Derived Composite Material for High-Energy Aqueous Hybrid Supercapacitor (HSC) Electrodes

The necessity for substantial advancements in electrical energy storage systems is underscored by the increasing demand driven by the extensive integration of renewable energy sources into the grid, the growing popularity of hybrid and electric vehicles, and the escalating safety requirements. Supercapacitors, characterized by their high-power density, inherently superior safety features, and longer cycle life compared to other energy storage systems, are poised to meet these escalating expectations.In this research, an in situ dispersion of Metal-Organic Polyhedra (MOP)-18 in Matrimid is employed to construct a hybrid supercapacitor electrode with enhanced redox activity and improved electrical conductivity. A uniform solution of Matrimid and MOP-18 was electrospun, subsequently carbonized, and activated with CO2 to yield Cu/Cu2O decorated carbon fiber electrode materials. The remarkable solubility of MOP-18 was leveraged to ensure the even dispersion of nanoparticles. The thermally decomposable porous structure of MOP-18 augmented the surface area and electrolyte accessibility of the fabricated electrode. Conversely, Matrimid provided a highly conductive free-standing carbon for the electrode.The amalgamation of these factors culminated in a notable enhancement in capacitance and energy density in a 6 M KOH electrolyte solution. The synthesized composite material achieved a peak capacitance of 253 Fg-1 and an energy density of 12.5 Whkg-1 at a current density of 1 Ag-1. The materials, methods, and techniques employed in the study can be readily scaled up industrially without significant alterations. As illustrated in the study, the use of soluble metal-organic structures to deliver redox-active materials in highly conductive carbon can result in composite electrode materials with synergistic properties. Figure 1

Biosensor Based on Zif-8-905% Metal-organic Nanocomposite and Carbon Nanotubes Associated with Concanavalin a for Detection of Alpha-fetoprotein

Introduction:: Lung carcinoma presents an aggressive evolution, with its carriers having reduced survival. Late diagnosis is one of the main factors of death. In the neoplasia in question, there is an established correlation with increases in Alpha-Fetoprotein (AFP) serum concentrations. Methos: Commonly used diagnostic methods are invasive or inaccessible. Therefore, a low-cost, non-invasive method would be extremely promising, and biomarkers can be used to achieve this goal. Electrochemical biosensors are a promising approach for detecting analytes of clinical interest using innovative bioreceptors. In this work, we obtained an electrochemical biosensor based on a hybrid ligand metal-organic structure (ZIF-8-905%) and functionalized carbon nanotubes (MWCNTs- COOH) in association with the lectin Concanavalin A (ConA), as a biorecognition element for detecting AFP in human serum from patients with lung carcinoma. Cyclic Voltammetry (CV), Square Wave Voltammetry (SWV), and Electrochemical Impedance Spectroscopy (EIS) were used to characterize the development of this biosensor. Microscopic analysis through Atomic Force Microscopy (AFM) revealed the formation of ConA-AFP complexes, pointing out the sensor's ability to identify the target analyte. Results: The blocking electron transfer effect in the electrode-redox pair interface assessed AFP detection. The ZIF-8-905%/MWCNTs-COOH/ConA platform exhibited a limit of detection (LOD) of 7.98 ng/mL, and a limit of quantification (LOQ) of 23.78ng/mL was also estimated. In addition, the biosensor showed excellent selectivity towards interfering biomolecules. Conclusion:: Therefore, the biosensor represents an efficient form of detection, contributing to research that aims to detect tumor biomarkers and ensure better prognoses.

Mechanochemical Synthesis of MOF-303 and Its CO2 Adsorption at Ambient Conditions.

Metal-organic structures have great potential for practical applications in many areas. However, their widespread use is often hindered by time-consuming and expensive synthesis procedures that often involve hazardous solvents and, therefore, generate wastes that need to be remediated and/or recycled. The development of cleaner, safer, and more sustainable synthesis methods is extremely important and is needed in the context of green chemistry. In this work, a facile mechanochemical method involving water-assisted ball milling was used for the synthesis of MOF-303. The obtained MOF-303 exhibited a high specific surface area of 1180 m2/g and showed an excellent CO2 adsorption capacity of 9.5 mmol/g at 0 °C and under 1 bar.

Encapsulation of Cu-modified SnO2 yolk-shell in V2O5-amalgamated wrinkled g-C3N4 lamella for boosting antibiotic photodegradation

The remarkable application of tin oxide in various domains is indebted to its photoelectronic merits. However, significant efforts to discover its photocatalytic potential were restricted through arduous challenges, which were the amelioration of light-harvesting and -utilizing. In fact, the uncommon light absorption energy has drawn veil over the brilliance of astounding oxidation potential, which is much more than that of TiO2. Herein, our attention was focused on the taking advantages of self-template structure for simultaneously enjoying the two sides of photoelectronic justification as well as the S-step system for eminent charge dissociation. In this regard, the optimized Cu-modified SnO2 yolk-shell ((5)YS-CuSnO) spheres were engineered through the copper modulation into glycerate-assisted metal-organic structure. As a result, the exceptional light-harvesting was achieved through desirable defects and oxygen vacancy resulted from Cu-doping, and also efficient light-utilization was obtained by the multi-scattering/reflection effect resulted from multi-shell configuration. After the effectual incorporation (40 wt⁒) of (5)YS-CuSnO was encapsulated into the V2O5-decorated wrinkled g-C3N4 lamella (VO–WCN), the dual S-step VO-WCN@(5)YS-CuSnO introduced unprecedented levofloxacin (LFC) decontamination performance, which was kinetically 5.2 and 30.2-times greater than of the (5)YS-CuSnO and bare SnO2 yolk-shell. The conspicuous fulfillment of nanocomposite was manifested in the LFC mineralization, pharmaceutical effluent treatment within 360 min, and successive cycling reactions. The fusion of the extraordinary architecture of YS-CuSnO with S-Step system not only initiates the facile and practical photocatalytic exploitation, but shade light on some undeveloped side of tin oxide.

Adsorption of cephalexin from aqueous solutions by MIL-101 (Fe) metal–organic framework

Adsorption using metal–organic structures is one of the methods of eliminating antibiotics that has shown promising results so far. In this study, to remove the antibiotic cephalexin from water, metal–organic structure MIL-101(Fe) was used. After making the adsorbent, adsorption tests were carried out to remove cephalexin from the aqueous solution in batch mode. The effect of parameters, including initial adsorbent dosage, initial cephalexin concentration, pH, time, and temperature on the adsorption was investigated. Kinetic data showed that the cephalexin adsorption on MIL-101(Fe) followed the pseudo-second-order model. The cephalexin adsorption isotherm was consistent with Langmuir model, and the maximum absorption capacity at 45 °C was 16.44 mg/g. The thermodynamic parameters showed that the cephalexin adsorption on adsorbent is spontaneous, endothermic, and accompanied by an increase in entropy. Therefore, MIL-101(Fe) can be a promising adsorbent to remove cephalexin from aqueous solutions.

Synthesis, crystal structure and characterization of two new cobalt(II) metal–organic frameworks with 1,4-bis((1h-imidazol-1-yl)methyl) benzene and 1,3,5-tris[(1h-imidazol-1-yl)methyl]benzene ligands

Two novel CoII metal–organic frameworks {[Co(BIMB)2(H2O)2](SO4)·EG·3 H2O}n (I) and {[Co(TIMB)2](SiF6)}n (II) were hydrothermally synthesized by corresponding metal salt with organic ligands 1,3,5-tris[(1H-imidazol-1-yl)methyl]benzene (TIMB) or 1,4-bis((1H-imidazol-1-yl)methyl)benzene (BIMB). Crystal structural analysis reveals that they exhibit varied structures. Compound I contains two crystallographically unique CoII centers, each lying on an inversion center and having a slightly distorted octahedral environment. The BIMB ligands link the CoII cations to generate a three-dimensional porous framework with a 4-connected uninodal (65.8) topology. Compound II exhibits a two-dimensional sheeted metal-organic structure running parallel to the (0 0 1) plane, in which TIMB ligands join Co2+ centers having a six-coordinated octahedral structure. In the solid state, adjacent sheets are further bridged by guest SiF6 - anions via C–H…F hydrogen-bonding interactions, giving rise to a three-dimensional supramolecular network structure with a 2-nodal (3-c)2(6-c) net. The topological analysis suggests that the point Schläfli symbol of compound II is (43)2(46.66.83). In addition, their thermal stabilities have also been investigated.

Predicting Organometallic Intermediates in the Surface-Assisted Ullmann Coupling of Chrysene Isomers.

On-surface polymerization of functional organic molecules has been recently recognized as a promising route to persistent low-dimensional structures with tailorable properties. In this contribution, using the coarse-grained Monte Carlo simulation method, we study the initial stage of the Ullmann coupling of doubly halogenated chrysene isomers adsorbed on a catalytically active (111) crystalline surface. To that end, we focus on the formation of labile metal-organic precursor structures preceding the covalent bonding of chrysene monomers. Four monomeric chrysene units with differently distributed halogen substituents were probed in the simulations, and the resulting precursor structures were compared and quantified. Moreover, the effect of (pro)chirality of chrysene tectons on the structure formation was elucidated by running separate simulations in enantiopure and racemic systems. The calculations showed that suitable manipulation of the halogen substitution pattern allows for the creation of diverse precursor architectures, ranging from straight and winded chains to cyclic oligomers with enantiopure, racemic, and nonracemic composition. The obtained findings can be helpful in developing synthetic strategies for covalent polymers with predefined architecture and functionality.

Guiding the Formation of Metal-Organic Structures of 1,4-Diaminoanthraquinone through Surface-Based Cu Atoms.

The gradual guidance of the formation of metal-organic structures through surface-based Cu atoms for 1,4-diaminoanthraquinones (DAQs) has been studied by scanning tunneling microscopy (STM) at room temperature. On the Ag(110) surface, the transition from a hydrogen-bond network structure to metal-organic coordination structures of DAQs can be induced by introducing foreign copper atoms. Due to the weak interaction between DAQs and Ag(110), thermal treatment easily leads to the desorption of DAQs from the surface. To address this challenge, Cu(111) is selected as the substrate. Under thermal driving and in the presence of copper adatoms, the hydrogen-bond network structure of DAQs on the surface gradually undergoes a transition into a metal-coordinated structure, eventually leading to the formation of metal-organic complexes through amino dehydrogenation. It is demonstrated that the construction of a metal-organic coordination structure on metal surfaces is a result of the competition among factors such as metal atoms, functional groups of molecules, surface chemical activity, and temperature.

Self-assembly and dynamic exchange of cuboctahedral metal-organic cages.

Due to their unique physical and chemical properties, metal-organic cage structures have great potential for applications in various fields. However, current studies have mainly focused on highly symmetric structures assembled from single metal ions and organic ligands, limiting their diversity and complexity, and there are still relatively few studies on the dynamic formation process of metal-organic cages. Herein, we constructed a series of metal-organic cages with different sizes assembled from the highly-stable coordination of 2,2':6',2''-terpyridine-based tetratopic ligands and various metals ions such as Zn, Cu, Co and Fe. Furthermore, the intermolecular exchange process between the metal-organic cages was explored through the dynamic exchange of ligands, and the formation of a series of hybrid supramolecular nanocages together with their final tendency to form a predominant structure of M24L14L28 was observed. In addition, the binding of metal-organic cages with 5,10,15,20-tetrakis(3,4,5-trimethoxyphenyl) porphyrin-Zn was also investigated. This study not only expands the complexity and diversity of metal-organic cages, but also provides a new perspective for studying the dynamic behaviour of metal-organic cages.

Synthesis and activation of pH-sensitive metal-organic framework Sr(BDC)∞ for oral drug delivery.

Metal-organic frameworks (MOFs) are widely used in the biomedical industry. In this study, we developed a new method for obtaining a metal-organic structure of strontium and terephthalic acid, Sr(BDC), and an alternative activation method for removing DMF from the pores. Sr(BDC) MOFs were successfully prepared and characterized by XRD, FTIR, TGA, and SEM. The importance of the activation steps was confirmed by TGA, which showed that the Sr(BDC)(DMF) sample can contain up to a quarter of the solvent (DMF) before activation. In our study, IR spectroscopy confirmed the possibility of removing DMF by ethanol treatment from the Sr-BDC crystals. A comparative analysis of the effect of the activation method on the specific surface and pore size of Sr-BDC and its sorption properties using the model drug doxorubicin showed that due to the undeveloped surface of the Sr-(BDC)(DMF) sample, it is not possible to obtain an adsorption isotherm and determine the pore size distribution, thus showing the importance of the activation step. Cytotoxicity and apoptosis assays were carried out to study the biological activity of MOFs, and we observed relatively low toxicity in the tested concentration range after 48 h, with over 92% cell survival for Sr(BDC)(DMF) and Sr(BDC)(260 °C), with a decrease only in the highest concentration (800 mg L-1). Similar results were observed in our apoptosis assays, as they revealed low apoptotic population generation of 2.52%, 3.23%, and 2.77% for Sr(BDC)(DMF), Sr(BDC) and Sr(BDC)(260 °C), respectively. Overall, the findings indicate that ethanol-activated Sr(BDC) shows potential as a safe and effective material for drug delivery.

Phase Transitions of Naphthalene-2,3-carbonitride Steered by Solvent Effects and Metal Ion Concentration Variation.

The delicate regulation of structural phase transition can provide advanced approaches for fabricating desired and well-organized nanoarchitectures on surfaces. Introduction of metal ions into pure organic systems can facilitate the phase transition from hydrogen-bonded structures to metal-organic structures by coordinating with organic molecules. However, it remains a challenge to attain a phase transition dominated by variable metal coordination configurations through adjustment of the metal ion concentration. Herein, we report the phase transitions of naphthalene-2,3-carbonitride (2,3-DCN) molecules on highly oriented pyrolytic graphite (HOPG) under varying solvents and Cu2+ ion concentrations. By integrating data from scanning tunneling microscopy imaging and density functional theory calculations, it is demonstrated that phase transitions of 2,3-DCN occur through forming diverse coordination configurations where Cu2+ ions can coordinate with 2,3-DCN and 1-nonanoic acid or Cl- ions to form different ligand components with a coordination number of 4 when varying the molar ratios of 2,3-DCN to Cu2+ ion in the 1-nonanoic acid solvent. However, in the case of 1-heptanoic acid as a solvent, the self-assembly structure of 2,3-DCN only changes via the alteration of hydrogen bonding sites and Cu2+ ions do not coordinate with 2,3-DCN molecules. These findings provide valuable insights into the coordination behavior of metal ions in different solvents.

Synthesis of metal-organic framework hybrid nanocomposites based on MOFs@C3N4 with high selective separation ability for luteolin

Complex substrates found in certain extracts-particularly those containing high phenolic compounds with significant medicinal value-pose considerable challenges to developing molecularly imprinted membranes (MIMs) with specific recognition abilities. In this study, UiO-66-NH2, a metal–organic structure (MOF), was chosen as an optimizer to enhance the basic support material C3N4. A composite imprinted membrane based on MOFs was then prepared for the targeted adsorption of luteolin (LTL). This not only increases the surface area and pore capacity of the composite membranes, but also ensures unprecedented control over the membranes structure and good stability. To maximize the proportion of imprinted sites, we utilize an advanced boron affinity sol–gel imprinting technique that capitalizes on the exceptional response of the bifunctional monomer. By finely manipulating the imprinting process, controlled distribution of imprinted sites was achieved. Furthermore, the incorporation of Ag nanoparticles into the composite matrix of MIMs enhances selectivity and efficiency due to their plasmonic properties and high affinity for phenolic compounds, providing increased adsorption surface area and additional binding sites. The results showed satisfactory rebinding ability (56.25 mg g−1) and superselective (βAG/LTL = 4.43 and βCT/LTL = 8.49). It was worth noting that incorporating Ag nanoparticles into composite MIMs for the selective adsorption of LTL demonstrates significant potential. This includes enhanced selectivity, efficiency, and hydrophilicity of the membrane surface. Thus, enhanced hydrophilicity can establish stronger non-covalent interactions, namely hydrogen bonding and van der waals forces, with the target molecules, thereby significantly improving the adsorption capacity of the MIMs. The feasibility of this method was demonstrated via in-situ infrared analysis of the chemical structure changes before and after adsorption.

Synthesis of Large-Scale High-Quality Metal-Organic Frameworks on Cu(100) via Hierarchical Dehydrogenation Reactions.

Thermal stimulus has been considered as a promising strategy for controlling on-surface reactions, allowing the formation of diverse products on metal substrates. Here, we successfully achieve hierarchical dehydrogenation reactions of amino groups on a Cu(100) surface. By carefully adjusting the experimental parameters, we synthesize large-scale and low-defect density surface metal-organic frameworks on copper surfaces. Our work sheds light on a controllable route for the synthesis of high-quality metal-organic coordination supramolecular structures via on-surface chemistry.

One-pot growth of metal-organic frameworks on polymers for catalytic performance enhancement in the CO2 cycloaddition to epoxides

A novel approach is reported to prepare 3D-printed polymers that incorporate metal-organic frameworks (MOFs) through a one-pot growth process, involving covalent grafting and growth onto 3D polymeric surfaces. The resulting hybrid materials were subjected to comprehensive characterization using techniques such as SEM, XRD, FTIR, Raman, and XPS. The findings demonstrated an excellent dispersion of the inorganic units on the polymer matrix while preserving their metal-organic structure. The hybrid materials exhibited the presence of Lewis acid and basic groups within the MOF. The catalytic performance of these hybrid materials was evaluated in the mild cycloaddition reaction of carbon dioxide (CO2) to epoxides. Notably, the polymers incorporating UiO-67 MOFs displayed remarkable activity, even at low CO2 pressures and in the absence of auxiliary co-catalysts or additives. The catalytic activity of these hybrid materials exhibited a significant improvement, up to two orders of magnitude higher than analogous bulk MOFs. This observation highlights the superior performance of the 3D-printed polymer/MOF hybrids in this catalytic transformation.

Forecasting low framework density zeolites from synthesis descriptors using machine learning

The framework density (FD) of zeolites can be defined as the number of tetrahedrally coordinated atoms (T-atoms) per 1000 Å3 and it is used to distinguish zeolites from tectosilicates and is an important index for evaluating the structure-void ratio of a zeolite. While the synthesis of extra-large pore zeolites is well known in the literature, it is extremely challenging to prepare extra-large pore zeolites with a low framework density. Only a few extra-large pore zeolites with low framework density have been synthesized to date, which raises the question of why such zeolites are so difficult to synthesize? To obtain such novel zeolites, experimentalists use qualitative analysis to identify structural patterns in experimental data and fine-tune synthesis descriptors. The aim of this paper is to demonstrate that machine learning can be utilized to predict the framework density of zeolites from synthesis descriptors, thus providing a platform for developing new zeolite structures. A machine learning approach is applied in this study to correlate the molar composition of a gel containing 11 metal oxides, fluoride, water, hydroxide ions, and organic structure agents, as well as operating parameters, using a large collection of synthetic records of 151 zeolite frameworks compiled from the literature, along with the framework density and the type of ring that results. Besides providing excellent accuracy, the decision tree provides a heuristic insight into the chemistry of zeolite synthesis by showing the conditions that result in low framework density. The data as presented does not provide details. However, machine learning algorithms can be used to find hidden patterns in the data, providing a deeper understanding of the chemistry involved in the formation of low framework density zeolites. This approach can, in principle, be applied to the synthesis of any material to rationalize empirical knowledge and fine-tune the synthesis conditions to achieve the desired properties.

A highly carboxylated sponge-like material: preparation, characterization and protein adsorption

Producing of high-purity protein products using separation materials is critical to the biopharmaceutical industry. Efforts to achieve protein adsorption materials with large adsorption capacity and high processing efficiency have been challenging. Herein, a highly carboxylated sponge-like monolithic adsorbent material was prepared by using SiO2 nanofibers as a rigid support framework, and esterification crosslinking reactants with polyvinyl alcohol (PVA)/polymeric carboxylic acid (polyacrylic acid, PAA) as a functional organic binder, which were modified in situ on the nanofiber framework. The obtained PVA/PAA sponge-like monolithic adsorbent material (PVA/PAA SMAM) exhibits a porous structure and possesses mechanical stability and recoverability of underwater compression. The high porosity provides more sites for carboxyl groups, making PVA/PAA SMAM rich in carboxyl groups. Experiments showed that PVA/PAA SMAM selectively adsorbes proteins with high isoelectric points. Using Cytochrome C (Cyt-C) as the main model protein with a high isoelectric point, the maximum adsorption of Cyt-C by the PVA/PAA SMAM at pH = 9 was 3079.3 mg/g with a rapid equilibration time (40 min), which is clearly superior to the currently reported Metal-organic frame structure (MOF) composites for Cyt-C adsorption. The isothermal adsorption model for the Cyt-C adsorption of the PVA/PAA SMAM material agrees well with the Freundlich adsorption model and the quasi-first kinetic model. Excellent mechanical and chemical structural stability endow the PVA/PAA SMAM material with protein elution capacity and good reusability, and secondary structure of the protein after elution was unchanged. Subsequently, selective adsorption and separation of Cyt-C from porcine heart supernatant was successfully achieved with PVA/PAASMAM material. This work provides new materials with excellent performance for various bio-separation applications.

Structural Quantification of the Surface-Confined Metal-Organic Precursors Simulated with the Lattice Monte Carlo Method.

The diversity of surface-confined metal-organic precursor structures, which recently have been observed experimentally, poses a question of how the individual properties of a molecular building block determine those of the resulting superstructure. To answer this question, we use the Monte Carlo simulation technique to model the self-assembly of metal-organic precursors that precede the covalent polymerization of halogenated PAH isomers. For this purpose, a few representative examples of low-dimensional constructs were studied, and their basic structural features were quantified using such descriptors as the orientational order parameter, radial distribution function, and one- and two-dimensional structure factors. The obtained results demonstrated that the morphology of the precursor (and thus the subsequent polymer) could be effectively tuned by a suitable choice of molecular parameters, including size, shape, and intramolecular distribution of halogen substituents. Moreover, our theoretical investigations showed the effect of the main structural features of the precursors on the related indirect characteristics of these constructs. The results reported herein can be helpful in the custom designing and characterization of low-dimensional polymers with adjustable properties.