Simple Chemical Modification Research Articles

Creation of Excitation-Driven Hypervalent Tin(IV) Compounds For Aggregation-Induced Emission and Application to Thermoresponsive Luminescent Films Below Freezing Point.

Although many researchers have devoted their much effort to establish the strategy for developing a stimuli-responsive molecule and tuning of their properties according to the preprogrammed design, it is still challenging to create desired molecules from the scratch. We recently demonstrated that the molecules with a large structural difference between the theoretically optimized structures in the ground and excited states have a potential to exhibit stimuli-responsive luminescent properties. We defined these molecules as an excitation-driven molecule and have shown that they are a versatile platform for designing stimuli-responsive luminescent molecules. Herein, based on the concept of excitation-driven molecules, we show that the hypervalent tin-fused azomethine (TAm) compounds possessing aggregation-induced emission (AIE) properties can be obtained by simple chemical modification with a methyl group although conventional TAm derivatives are well known to be highly luminescent compounds in solution. Furthermore, by combining the solid-state luminescence property of AIE and the coordination number shifts of the hypervalent tin atom, the thermoresponsive films operating below the freezing point are fabricated with the polymer. In this study, we apply the concept of excitation-driven molecules to the hypervalent compounds and demonstrate to obtain the novel functional materials.

In-Situ construction of Bulge-like microstructures in sugarcane-based superhydrophobic membranes for efficient separation of water-in-oil emulsions

The separation of oil/water pollution is of great importance to environmental protection. However, the development of superwetting materials for efficient separation of surfactant-stabilized oil/water emulsions still faces challenges. As agricultural waste, sugarcane straw contains many hydrophilic groups and multilayered pore structures, making it suitable for purifying oil/water emulsions by simple chemical modification treatments. Herein, sugarcane-based superhydrophobic membranes (SSMs) were prepared by a facile vacuum impregnation method in hexadecyltrimethoxysilane (HDTMS) solution. The unique bulge-like microstructures were constructed in the intrinsic pores of sugarcane, which significantly increased the roughness and resulted in superhydrophobicity with the water contact angle of 153.5°. More importantly, the bulge-like structure is easy to break the emulsion and thus SSMs offer excellent separation efficiency (> 99 %), suitable fluxes (368 L•m−2•h−1) and strong cycling stability for surfactant-stabilized water-in-oil emulsions. In addition, SSMs can separate oil/water mixtures and directly adsorb oil from water with adsorption rates exceeding 99 %. SSMs have good durability and anti-mold adherence properties, and they do not lose their unique wetting properties even in harsh environments. More importantly, SSMs can be degraded in soil at the end of their life cycle, avoiding secondary pollution for the environment. This simple, in-situ impregnation technique offers a novel way to create green, inexpensive and stable biomass membranes for effective water-in-oil emulsion separation, showing great promise for use in oily wastewater treatment.

Local Isomeric Polar Nanoclusters Enabled Superior Capacitive Energy Storage Under Moderate Fields in NaNbO3-Based Lead-Free Ceramics.

The high-field energy-storage performance of dielectric capacitors has been significantly improved in recent years, yet the high voltage risks of device failure and large cost of insulation technology increase the demand for high-performance dielectric capacitors at finite electric fields. Herein, a unique superparaelectric state filled with polar nanoclusters with various local symmetries for lead-free relaxor ferroelectric capacitors is subtly designed through a simple chemical modification method, successfully realizing a collaborative improvement of polarization hysteresis, maximum polarization, and polarization saturation at moderate electric fields of 20-30kVmm-1. Therefore, a giant recoverable energy density of ≈5.0Jcm-3 and a high efficiency of ≈82.1% are simultaneously achieved at 30kVmm-1 in (0.9-x)NaNbO3-0.1BaTiO3-xBiFeO3 lead-free ceramics, showing a breakthrough progress in moderate-field comprehensive energy-storage performances. Moreover, superior charge-discharge performances of high-power density ≈182MWcm-3, high discharge energy density ≈4.3Jcm-3 and ultra-short discharge time <70ns as well as excellent temperature stability demonstrate great application potentials for dielectric energy-storage capacitors in pulsed power devices. This work provides an effective and paradigmatic strategy for developing novel lead-free dielectrics with high energy-storage performance under finite electric fields.

Fabrication of phosphorylated UiO-66 for efficient selective removal of Pb2+ from acidic wastewater

Metal-organic framework (MOF) materials have emerged as promising candidates for treating heavy metal wastewater because of their controllable pore size, high specific surface area, and abundant active sites. Nevertheless, the currently reported MOFs usually require near-neutral environments (pH = 5–6) to achieve efficient removal of Pb2+ and cannot be applied to acidic environments (pH = 2–3). In this work, the structurally stabilized zirconium-based MOF UiO-66 was chosen as the object of study. Three phosphate ester-based MOFs (UiO-66-(OPO3)X) containing different amounts and spatial positions were designed and prepared by simple chemical modification and used to remove Pb2+. Adsorption experiments showed that they could reach adsorption equilibrium in 30 min with excellent adsorption rate. Owing to the unique ionization ability of the phosphate ester group, UiO-66-(OPO3)X maintains a high removal efficiency of Pb2+ even at pH = 2 and pH = 3. In addition, selectivity and competition experiments demonstrated that UiO-66-(OPO3)X possessed excellent selectivity and anticompetitive ability towards Pb2+.The excellent regeneration performance demonstrates their value for practical application. Moreover, the adsorption mechanism was investigated in detail by experiment combined with density functional theory (DFT).

Fabrication of biodegradable superhydrophobic Zn-Fe coating on ultra-light Mg-Li alloy

As a typical biodegradable and biocompatible light metal, magnesium (Mg) and its alloys exhibit significant prospects for various applications, especially in biomedical materials. Unfortunately, their actual application fields have been restricted by too fast degradation/corrosion rate. Both zinc (Zn) and iron (Fe) are biodegradable and biocompatible but stabler thermodynamically. It's one of the considerable refreshing strategies for controlling the degradation rate of Mg substrate by constructing a ZnFe coating with superhydrophobicity on it. However, it's challenging and rarely reported due to the high chemical reactivity of Mg. This study reports the successful in-situ synthesis of ZnFe coatings with hierarchical micro-/nano-scale structures and superhydrophobicity on ultra-light MgLi alloy by employing an innovative weak alkaline aqueous bath followed by simple chemical modification. Their micromorphology, chemical and phase compositions as well as surface wettability were comprehensively analyzed by FE-SEM, EDS, XRD, XPS, FT-IR, and a contact angle measuring instrument. Furthermore, the degradation behavior of the typical samples was evaluated by modern electrochemical measurement technology. The results revealed that the coating comprised dense micro-papillary structures and nanosheets, exhibiting a static contact angle of droplets up to 161.5° and a sliding angle of 3.0°. In addition, the obtained sample demonstrated a significantly reduced degradation rate compared to the bare magnesium alloy.

Silver nanoparticles coated cellulose-based flexible membrane with excellent UV resistance, high infrared reflection and water resistance for personal thermal management

Designing of a green and multifunctionally integrated cellulose-based flexible wearable material with personal thermoregulation, water and ultraviolet (UV) resistance is essential for the development of personal thermal management and smart textiles. Herein, a hydrophobic silver nanoparticles cellulose-based membrane (H-AgNPs/CEPCM) was prepared through simple solution blending, spin-coating process and chemical vapor modification. The prepared membrane exhibited excellent UV resistance due to the synergistic effect of carbon quantum dots (CQDs) as well as UV-absorbing functional groups. The spin-coated AgNPs layer with high infrared reflectivity has great radiant insulation, and temperature was reduced by 3.4 °C compared with H-CEPCM in indoor environment. Furthermore, the mechanical properties of H-AgNPs/CEPCM were significantly improved by the introduction of amide and ether bonds, as well as a large number of hydrogen bonds. This led to a tensile strength of 23.21 MPa and an elongation at break of 16.57 %, while also providing water resistance. Additionally, the H-AgNPs/CEPCM exhibited outstanding thermal stability and hydrophobicity. This work may provide a feasible and promising strategy for the construction of multifunctional integrated cellulose membrane materials for radiant insulation, outdoor textiles and novel UV protection applications.

Outstanding Energy-Storage Density Together with Efficiency of above 90% via Local Structure Design.

Dielectric ceramic capacitors with high recoverable energy density (Wrec) and efficiency (η) are of great significance in advanced electronic devices. However, it remains a challenge to achieve high Wrec and η parameters simultaneously. Herein, based on density functional theory calculations and local structure analysis, the feasibility of developing the aforementioned capacitors is demonstrated by considering Bi0.25Na0.25Ba0.5TiO3 (BNT-50BT) as a matrix material with large local polarization and structural distortion. Remarkable Wrec and η of 16.21 J/cm3 and 90.5% have been achieved in Bi0.25Na0.25Ba0.5Ti0.92Hf0.08O3 via simple chemical modification, which is the highest Wrec value among reported bulk ceramics with η greater than 90%. The examination results of local structures at lattice and atomic scales indicate that the disorderly polarization distribution and small nanoregion (∼3 nm) lead to low hysteresis and high efficiency. In turn, the drastic increase in local polarization activated via the ultrahigh electric field (80 kV/mm) leads to large polarization and superior energy storage density. Therefore, this study emphasizes that chemical design should be established on a clear understanding of the performance-related local structure to enable a targeted regulation of high-performance systems.

Radical‐Formation Management: Towards Aza‐Analogues of the Benzothioxanthene Imide

AbstractWhile benzothioxanthene imide (BTI) has shown promise in organic electronics and more recently in photodynamic therapy, its full potential remains yet undiscovered. In this context, this study repots the synthesis and characterization of aza derivatives in which the characteristic sulfur atom is replaced by an amino group. Adapted from the synthetic route of the BTI, a way was found to control the electronic structure of the radical intermediates, by means of a simple chemical modification. As a result, either the thermodynamically six‐membered or the kinetically favored five‐membered ring regioisomers can selectively be accessed. Photophysical rationalization of their structure‐property relationships confirmed the richness, versatility and tunability of this class of rylene imide‐based dyes.

A Mechanically Resilient and Tissue-Conformable Hydrogel with Hemostatic and Antibacterial Capabilities for Wound Care.

Hydrogels are used in wound dressings because of their tissue-like softness and biocompatibility. However, the clinical translation of hydrogels remains challenging because of their long-term stability, water swellability, and poor tissue adhesiveness. Here, tannic acid (TA) is introduced into a double network (DN) hydrogel consisting of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA) to realize a tough, self-healable, nonswellable, conformally tissue-adhesive, hemostatic, and antibacterial hydrogel. The TA within the DN hydrogel forms a dynamic network, enabling rapid self-healing (within 5min) and offering effective energy dissipation for toughness and viscoelasticity. Furthermore, the hydrophobic moieties of TA provide a water-shielding effect, rendering the hydrogel nonswellable. A simple chemical modification to the hydrogel further strengthens its interfacial adhesion with tissues (shear strength of ≈31kPa). Interestingly, the TA also can serve as an effective hemostatic (blood-clotting index of 58.40±1.5) and antibacterial component, which are required for a successful wound dressing. The antibacterial effects of the hydrogel are tested against Escherichia coli and Staphylococcus aureus. Finally, the hydrogel is prepared in patch form and applied to a mouse model to test in vivo biocompatibility and hemostatic performances.

Dispersant-free supra single-walled carbon nanotubes for simultaneous and highly sensitive biomolecule sensing in ex vivo mouse tissues

A simple sensing methodology for rapid detection of multiple biomolecules in human health diagnostics remains a significant challenge. Herein, we developed a novel dispersant-free supra single-walled carbon nanotube (supra SWCNT)-coated glassy carbon electrode (GCE) for simultaneous sensing of biomolecules, such as ascorbic acid (AA), dopamine (DA), and uric acid (UA), in ex vivo mouse tissues. Supra SWCNTs with stable hydrogen bonds were synthesized via a simple chemical modification, after which they were characterized and confirmed using different physicochemical and electrochemical techniques. The supra SWCNT-coated GCE exhibited simultaneous sensing of AA, DA, and UA at linear dynamic ranges with lower detection limits of 12, 0.02, and 0.36 μM, respectively. Furthermore, they demonstrated high selectivity (with co-existing interference) and excellent reproducibility for effective sensing of the target biomolecules in different real samples. The rapid functioning, low cost, scalable preparation, and enhanced applicability for simultaneous sensing of target biomolecules in Parkinson's disease-induced mouse liver, kidney, and brain tissues suggest the suitability of the developed sensor for real-world applications.

Solvent-free functionalization of sawdust with quaternary ammonium groups: Application to the biosorption of two anionic dyes

The improvement of sawdust reactivity through simple chemical modification strategies represent an interesting method to extend the field of application or improve the natural performances of this abundant and available waste. In this work, sawdust was modified with Glycidyltrimethylammonium chloride (GTAC), an organic compound bearing a quaternary ammonium group. The objective was to obtain a modified sawdust with a permanent cationic charge. The modification of the material was confirmed by solid state 13C NMR and FTIR spectroscopy. The anion exchange capacity of modified sawdust (Sa-G) was demonstrated by the ability of sawdust to exclusively adsorb cations before modification and anions after modification. This anionic exchange property was applied for the adsorption of two anionic dyes (Procion Red MX-5B (PR) and Evans Blue (EB)). Generally, the material was more effective in acidic conditions due to the acid-base properties of sawdust. Compared to EB, the less charged and smaller PR adsorbs more quantitatively on the material and with faster kinetics (Equilibrium reached after only 30 min, while more than 24 h were needed in the case of EB). Thermodynamic study also reveals an exothermic process in the case of PR and endothermic in the case of EB. Under optimal conditions, the maximum adsorption capacities were 121.8 μmol g−1 for PR and 103.1 μmol g−1 for EB. Desorption tests showed that the material can be recycled by desorption of dyes in 0.1 M sodium hydroxide solution. After 5 adsorption-desorption cycles performance losses of only 15% for EB and 30% for PR were recorded.

Intrinsically Nonswellable Multifunctional Hydrogel with Dynamic Nanoconfinement Networks for Robust Tissue-Adaptable Bioelectronics.

Developing bioelectronics that retains their long-term functionalities in the human body during daily activities is a current critical issue. To accomplish this, robust tissue adaptability and biointerfacing of bioelectronics should be achieved. Hydrogels have emerged as promising materials for bioelectronics that can softly adapt to and interface with tissues. However, hydrogels lack toughness, requisite electrical properties, and fabrication methodologies. Additionally, the water-swellable property of hydrogels weakens their mechanical properties. In this work, an intrinsically nonswellable multifunctional hydrogel exhibiting tissue-like moduli ranging from 10 to 100kPa, toughness (400-873 J m-3 ), stretchability (≈1000% strain), and rapid self-healing ability (within 5min), is developed. The incorporation of carboxyl- and hydroxyl-functionalized carbon nanotubes (fCNTs) ensures high conductivity of the hydrogel (≈40Sm-1 ), which can be maintained and recovered even after stretching or rupture. After a simple chemical modification, the hydrogel shows tissue-adhesive properties (≈50kPa) against the target tissues. Moreover, the hydrogel can be 3D printed with a high resolution (≈100µm) through heat treatment owing to its shear-thinning capacity, endowing it with fabrication versatility. The hydrogel is successfully applied to underwater electromyography (EMG) detection and ex vivo bladder expansion monitoring, demonstrating its potential for practical bioelectronics.

Ionic Liquids as Organocatalysts and Solvents for Lignocellulose Reactions.

Ionic liquids (ILs) are the only media that can allow the homogeneous organocatalytic reactions of lignocellulosic biomass (lignocellulose), since the designability of their cations and anions offers the dual functions of solubility and catalytic activity. This review provides an account of our recent achievements in the organocatalytic approaches for converting lignocellulose into polymer materials based on the principles of IL design that we have originally established. These methodologies include the simple and mild chemical modification of cellulose and lignin under high conversions, with high selectivity, and/or with efficient atom economy. Similar reactions and subsequent fractionation processes are applied to lignocellulose, and a highly productive reaction system is developed using a twin-screw extruder that is specific to the IL media.

The unexpected mechanism of transformation from conventional room-temperature phosphorescence to TADF-type organic afterglow triggered by simple chemical modification

This study presents the mechanism of transformation of afterglow induced by specific chemical reactions. Consequently, highly efficient red TADF-type afterglow materials that counteract with the energy gap law have been achieved.

Aptamers 101: aptamer discovery and in vitro applications in biosensors and separations.

Aptamers are single-stranded nucleic acids that bind and recognize targets much like antibodies. Recently, aptamers have garnered increased interest due to their unique properties, including inexpensive production, simple chemical modification, and long-term stability. At the same time, aptamers possess similar binding affinity and specificity as their protein counterpart. In this review, we discuss the aptamer discovery process as well as aptamer applications to biosensors and separations. In the discovery section, we describe the major steps of the library selection process for aptamers, called systematic evolution of ligands by exponential enrichment (SELEX). We highlight common approaches and emerging strategies in SELEX, from starting library selection to aptamer-target binding characterization. In the applications section, we first evaluate recently developed aptamer biosensors for SARS-CoV-2 virus detection, including electrochemical aptamer-based sensors and lateral flow assays. Then we discuss aptamer-based separations for partitioning different molecules or cell types, especially for purifying T cell subsets for therapeutic applications. Overall, aptamers are promising biomolecular tools and the aptamer field is primed for expansion in biosensing and cell separation.

Efficient electrocatalytic oxygen reduction reaction of thermally optimized carbon black supported zeolitic imidazolate framework nanocrystals under low-temperature.

Turning commercially available low-cost conducting carbon black materials into functional electrocatalytic electrode media using simple surface chemical modification is a highly attractive approach. This study reports on remarkably enhanced oxygen electrocatalytic activity of commercially available Ketjenblack (KB) by growing a non-precious cobalt metal-based zeolitic-imidazolate framework (ZIF-67) at room temperature in methanol solution followed by a mild thermolysis. The resulting Co@CoOx nanoparticle decorated nitrogen-doped KB derived from the optimized ZIF-67 : KB weight ratio of hybrid samples at 500-600 °C shows high performance for the oxygen reduction reaction (ORR) with impressive Eonset and E1/2 values of ∼0.90 and ∼0.83 V (vs. RHE), respectively in 0.1 M KOH electrolyte. Such ORR activity is comparable to, or better than many metal@metal-oxide-carbon based electrocatalysts synthesized under elevated carbothermal temperatures and using multicomponent/multistep chemical modification conditions. Therefore, a simple electrocatalyst design reported in this work is an efficient synthesis route that not only utilises earth-abundant carbon black but also comprises scalable room temperature synthesized ZIF-67 following mild thermolysis conditions under 600 °C.

Mixing nitrogenous ligands in osmium(VI)ligand-polysaccharide complexes. Voltammetric sensing

• Electroinactive dextran was modified with complexes of Os(VI) and nitrogenous ligands. • Os(VI)ligand modified dextran is electroactive and yields several redox peaks. • Nitrogenous ligand type significantly influences interfacial properties of modified dextrans. • Ligand combination can improve dextran analysis comparing to one-ligand modification. Simple chemical modification of carbohydrates with complexes of sixvalent osmium and nitrogenous ligands (Os(VI)L) changes electro inactive carbohydrates to electroactive species. In this work we show that the type of the nitrogenous ligand (L) significantly influences adsorption of Os(VI)L-modified dextrans at a charged surface. Modification by mixture containing two ligands can improve electrochemical analysis in comparison to simple modification only with one ligand. For instance, modification with complexes of Os(VI) and mixture of N,N,Ń,Ń-tetramethylethylenediamine (temed) with 2,2́-bipyridine (bipy) allows to (i) determine the concentration of Os(VI)L modified dextran in one order higher range as in case of dextran modified only with Os(VI)temed and (ii) discriminate between various polysaccharides differing in building units and structures.

Molecular Modification of Lignin-Based Carbon Materials: Influence of Supramolecular Bonds on the Properties

For the application of lignin-based materials, it is necessary to develop simple and efficient chemical modification strategies for lignin. In this work, the iodization modification strategy is selected to improve the specific surface area and graphitization degree of lignin-based carbon fibers. The introduction of an iodine atom can effectively increase the π electron cloud density of the lignin aromatic hydrocarbon structure. High π electron cloud density can effectively enhance the π-π interaction force between lignin molecules (the supramolecular bonds). The biomass precursors with this intermolecular microstructure exhibit good thermal stability and can maintain the original fibrous morphology during high-temperature treatment, which is beneficial for increasing the specific surface area of biomass-based carbon materials. Furthermore, this intermolecular microstructure also contributes to the graphitization of biomass precursor materials and reduces the spacing of graphite micro-lamellae. The obtained lignin-based carbon fibers with iodization modification exhibit a specific capacitance of 333 F/g at a current density of 1 A/g in the three-electrode tests in 6 M KOH solution. As the assembled supercapacitor, the specific capacitance of lignin-based carbon fibers reaches 87 F/g in 1 M Na2SO4 solution. Compared to other modification processes for raw materials, this strategy is simple and efficient and has reference value for the synthesis of other high-performance biomass-based materials.

Multifunctional hybrid interface enables controllable zinc deposition for aqueous Zn-ion batteries

Aqueous Zn-ion batteries have gradually become a suitable choice for large-scale energy storage systems owing to their safety and lower cost. However, Zn metal anodes typically suffer from uneven electrodeposition and zinc dendrite formation, which restricts Zn-ion batteries from being used in further applications. To mitigate this problem, a simple and quick chemical surface modification is employed to construct a multifunctional hybrid interface consisting of ZnF2 and Sn on the surface of the Zn metal anode. ZnF2 show a low diffusion energy barrier for Zn2+, effectively shield the direct corrosive reaction from the aqueous electrolyte, and simultaneously increase the hydrogen evolution potential of the Zn electrode. Furthermore, the Sn particles provide a large number of nucleation sites and charge centers, avoiding the direct growth of dendrites. The interface-modified Zn anode achieve stable cycles of 700 h and 500 h at high current densities of 5 and 10 mA/cm2, respectively, while the assembled Zn@ZnF2–Sn||V2O5 full battery achieve over 400 stable cycles at 1 A/g. This work uncover the internal mechanism of inhibiting Zn dendrites by the multifunctional interface, providing a means for stabilizing the Zn anode under practical conditions.

Superhydrophobic polypropylene sorbent derived from discarded face masks: A highly efficient adsorbent for oil spill sorbent.

Globally, an estimated 130 billion face masks are used and disposed of every month. Thus, recycling or upcycling discarded face masks has attracted significant attention due to economic benefits and environmental concerns. To reduce the amount of used face masks going to waste, this study features a superhydrophobic face mask prepared by simple chemical modification with environmentally preferable alkane solvents (n-hexane, n-heptane, and n-decane), that is effective as a sorbent for oil spill cleanup. All alkanes examined increased the surface roughness of the face masks and improved face mask hydrophobicity. The heptane treated face mask (at 90°C for 1h), can adsorbed Arabian light crude oil up to 21 times of their weight on the water surface. In addition, chloroform, toluene, gasoline, and diesel were adsorbed 18, 13, 8 and 16 times, respectively. More importantly, heptane has a high recycling efficiency as a treatment solvent and is reusable for at least 10 cycles of mask surface treatment. Consequently, this inexpensive and easily fabricated material is a promising development in waste face mask (WFM) upcycling.