Multiple Hydroxyl Research Articles

Removal of toxic dye from dye-laden wastewater using a new nanocomposite material: Isotherm, kinetics and adsorption mechanism

In this study, (hemi)cellulosic biochar-based environment-friendly non-toxic nanocomposite (nAg-AC) was fabricated for an inordinate overlook of toxic dye-laden wastewater depollution. This hybrid nanocomposite grafted with silver nanoparticles, numerous hydroxyl and π-bond containing functional groups exhibited outstanding physicochemical properties. FESEM images indicated the heterogeneous porous structure of nAg-AC, while BET analysis revealed mesoporous property with a significant increment of overall surface area (132%). Imbedding of silver nanoparticles and the presence of multiple hydroxyl groups was evident from the XRD and XPS spectrum. Further, the TGA result indicated excellent thermal stability, and FTIR analysis suggested the involvement of surface functional groups like –OH, =C = O, =NH, =C = C = , and –CH in Rhodamine B (RhB) adsorption. The adsorbent matrix provided the overall mechanical strength and facilitated recycling, while the functional matrix (biochar) provided the adsorptive locus for augmented RhB adsorption efficiency (92.77%). Experiments pertaining to adsorption isotherms and kinetics modeling suggested that RhB was removed through multilayer chemisorption on the heterogeneous nAg-AC surface. The main RhB adsorption mechanism included cumulative efforts of H-bindings, π-π stacking interaction, pore-filling, and electrostatic interactions. The nAg-AC maintained mechanical robustness with significant RhB adsorption even after three consecutive regeneration cycles signifying facile recycling. The nAg-AC displayed an outstanding efficacy for the real industrial wastewater depollution, indicating high effectiveness for practical environmental applications. Finally, the cost analysis (incorporating economic, environmental, and social dimensions) suggested a significant role of the nAg-AC in promoting and establishing sustainable development with the circular economy.

Synthesis of 2-Deoxyglycosides Bearing Free Hydroxyl Substituents on the Glycosyl Donor.

Recent efforts in the field of carbohydrate chemistry have focused on the site- and stereocontrolled synthesis of O-glycosides derived from acceptors bearing multiple hydroxyl substituents. By comparison, there are few examples of the site-selective synthesis of O-glycosides bearing free hydroxyl substituents on the donor reagent. Here, we report the application of an umpolung glycosylation strategy to the synthesis of O-glycosides derived from donors bearing free hydroxyl substituents. The reaction proceeds via prior deprotonation of one or more free hydroxyl groups on a thiophenylglycoside donor, reductive lithiation to generate an anomeric anion intermediate, and addition of this anion to an alkyl 2-(2-methyltetrahydropyranyl) peroxide. By this approach, α-linked glycosides were obtained in 39-84% yields and with >50:1 α/β selectivities. In many instances, β-linked products could be obtained by thermal equilibration of the anomeric anion intermediate (selectivities = 3.8-8:1 β/α; yields = 33-68%). The strategy is applicable to polyhydroxyl donors bearing up to three free hydroxyl groups, N-acylated carbohydrates, and the single-flask syntheses of oligosaccharides.

Adhesive hydrogels tailored with cellulose nanofibers and ferric ions for highly sensitive strain sensors

Conductive hydrogels are regarded as one of the promising synthetic materials for emerging applications such as soft robotics, bioelectronics, and wearable devices. Herein, poly (N- [tris (hydroxymethyl) methyl] acrylamide-co-acrylamide) (P (THAM/AM)) adhesive hydrogels were tailored by physically cross-linking with cellulose nanofiber (CNF). Compared with chemical crosslinker (N,N'-methylene bisacrylamide), CNF complexing with multiple hydroxyl groups on P (THAM/AM) chains led to the formation of numerous hydrogen bonds, endowing the hydrogel with additional energy dissipation and resulting in a better strength reinforcement for adhesive hydrogels. Furthermore, we introduced ferric ions (Fe3+) into the hydrogel to make the hydrogel conductive for producing a strain sensor with desired adhesion, high sensitivity, fast response time, and superior durability. The fabricated hydrogel strain sensor attached well to human skin and was able to translate both large and subtle human motions into relative resistance changes, showing its promising applications in wearable electronics for human motion detection.

Ag nanozyme strengthened by folic acid: Superior peroxidase-mimicking activity and application for visual monitoring of dopamine.

Dopamine (DA) is an important neurotransmitter; however, any excess or deficiency of DA will cause several diseases in humans. To monitor DA efficiently and conveniently, a Ag nanozyme strengthened by bioactive folic acid (FA@AgNPs) was developed by homogeneous redox assembly. After the microstructure and performance were characterized in detail, it was noted that the proposed FA@AgNPs possessed superior peroxidase-like activity due to the ultra-small Ag nanoparticles and multiple amino, hydroxyl, and aromatic rings in FA. FA@AgNPs accelerated the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) with a low Michaelis constant (Km) and high maximal reaction rate (Vmax). Importantly, the characteristic absorbance intensity of FA@AgNPs-TMB-H2O2 at 652 nm (A652) was exclusively deteriorated in the presence of trace DA, accompanied by a visual color change from blue to colorless. Under the optimized conditions (pH 4.0, 300 μL 1.5 mM TMB, 300 μL 1.0 M H2O2 and incubated for 30 min at room temperature), there expressed an excellent linear relationship between lgA0/A652 and cDA from 1.0 ×10-8 to 6.67×10-6 mol/L with a low limit detection of 7.1×10-10 mol/L (S/N=3). When applied for monitoring of DA in real fruit juice and pharmaceutical samples, the recovery was between 96.6% and 104.9%, with RSD less than 2.2%. The enhanced peroxidase-like activity of the FA@AgNP system and its selective recognition mechanism for DA are also proposed.

Ultra-high moisture stability perovskite films, soaking in water over 360 min

Perovskite solar cells (PSCs) have attracted wide publicity via their excellent photoelectric properties. Nevertheless, the relative low formation energy and soft lattice of perovskite make it vulnerable to external environmental factors, especially the moisture. Inevitably, water molecules would remain in PSCs modules during practical production. Trace amounts of free water could not only destroy perovskite film, but also trigger metal electrode oxidation forming “snail tracks”. Most previous reports simply block perovskite film contact with water, ignoring the migration damage of free water in PSCs system. Herein, Sorbitan Monolaurate (Span 20), with multiple hydroxyl, ether, carbonyl groups and long alkyl chain, was adopted to post-treat the surface of perovskite. The hydrophilic groups can effectively absorb the slight free water in PSCs system, while the hydrophobic group would protect perovskite film from erosion. Shockingly, the modified perovskite films are hydrophilic, and present outstanding water stability, soaking in water over 360 min. The perovskite films morphology, crystallinity, photoelectric properties and decomposition processes are also improved by Span 20 passivation. In addition, the Span 20/IPA post-treatment has a large concentration operation window (5–100 mg/mL). The optimum power conversion efficiency (PCE) of devices increased to 22.13%, and preserved over 90% of the initial PCE during 29 d air aging (humidity: 60 ∼ 80 RH). This work overturns the popular concept of perovskite water stability, and provides a novel sight to improve the long-term stability of perovskite.

Hydroxy-safflower yellow A composites: An effective strategy to enhance anti-myocardial ischemia by improving intestinal permeability

Hydroxy-safflower yellow A (HSYA) is the chief component of safflower against myocardial ischemia (MI), and belongs to biopharmaceutics classification system (BCS) III drugs. Its structure contains multiple hydroxyl groups, contributing to its high polarity and poor oral bioavailability. The main objective of this study was to probe the potential of oral penetration enhancer n-[8-(2-hydroxybenzoyl) amino] sodium octanoate (SNAC) and cationic copolymer Eudragit®EPO (EPO) to promote absorption of HSYA. HSYA composites (SNAC-HSYA-EPO) were formed by hydrogen bonding and van der Waals force. SNAC-HSYA-EPO has biocompatibility, and can improve the membrane fluidity, uptake, transport, and penetration of Caco-2 cells. The mechanism of promoting of SNAC-HSYA-EPO may be related to energy and P-glycoprotein (P-gp) when compared with the inhibitor NaN3 and verapamil group. In the pharmacokinetic (PK) results, SNAC-HSYA-EPO significantly improved oral bioavailability. Pharmacodynamics (PD) results determined that SNAC-HSYA-EPO could improve the symptoms of MI. The mechanism of the SNAC-HSYA-EPO anti-MI is related to alleviating inflammation and anti-apoptosis to protect the heart. In summary, SNAC-HSYA-EPO prepared in this study possessed a complete appearance, high recombination rate and excellent oral permeability promoting ability. SNAC-HSYA-EPO has the potential to improve oral bioavailability and further enhance the anti-MI effect of HSYA.

Efficient Greener Visible‐Light‐Catalyzed Debenzylation of Benzyl Ethers and Esters: A Gateway to Wider Exploitation of Stable Benzyl Protecting Groups

AbstractA non‐hydrogenolytic mild deprotection strategy for stable benzyl protection of hydroxyl group is one of the long‐cherished goals in multistep synthesis involving carbohydrates or compounds with multiple hydroxyl groups. A greener organo‐photocatalytic method has been developed for mild and efficient visible light catalytic deprotection of benzyl group from benzyl ether and benzyl ester. The newly developed method in ambient condition with only 1 mol% of catalyst loading can efficiently remove highly stable benzyl protection from ethers and esters of wide substrate scope with excellent functional group tolerance, thus proved to be suitable for final stage deprotection. Employment of molecular oxygen as terminal oxidant and excellent yield in the multigram scale reaction signifies the eco‐friendliness, robustness and industrial applicability of the method.

Controllable Polymerization of N -Substituted β-Alanine N -Thiocarboxyanhydrides for Convenient Synthesis of Functional Poly(β-peptoid)s

Controllable Polymerization of <i>N</i> -Substituted β-Alanine <i>N</i> -Thiocarboxyanhydrides for Convenient Synthesis of Functional Poly(β-peptoid)s

Growing Impact of Carbohydrate‐Based Organocatalysts

AbstractOrganocatalysis has emerged as one of the most progressive and prevailing field of organic synthesis to assist green chemistry. Constantly increasing demand of promising scaffolds to develop potent organocatalysts has impelled researchers to utilize the unique traits of carbohydrate moiety in this field. Biological significance of carbohydrates, as well as, their high natural abundance as chiral non‐racemic material, presence of multiple hydroxyl groups, several stereogenic centres, and easily modifiable structure make this moiety an appropriate skeleton to develop organocatalysts to enhance productivity and selectivity of a chemical transformation. 21st Century has witnessed the progress of carbohydrate moiety in development of organocatalysts from obscurity to eminence. This review encapsulates the importance of carbohydrate scaffolds in organocatalysis mainly dealing with the synthesis and applications carbohydrate‐derived organocatalyst in different common organic reactions with their significance and future purspectives.

Kinetic and stability study on the immobilized enzymatic step of one‐pot dimerization of 2‐[2‐(dimethylamino)ethoxy]ethanol

Tertiary amine catalysts (TACs) are essential organic molecules used in polyurethane manufacturing. Synthesis of these chemicals involves the use of catalytic transition metals at high temperatures and high pressures. Simple amine systems react easily with transition metals; however, amine systems with multiple hydroxyl groups and methylamine complexes produce significant byproducts. In this study, synthesis that forgo transition metals is explored. Enzymes can provide a clean industrial alternative to transition metal use. 2‐[2‐(dimethylamino)ethoxy]ethanol (DMAEE) is the monomer used in the synthesis of a model TAC. When DMAEE is first enzymatically oxidized, the aldehyde can serve as an electrophile for 2‐(methylamino)ethanol (MMEA), forming the DMAEE dimer. Choline oxidase catalysis is the first step of this pathway. Steady state kinetic parameters of choline oxidase with choline and DMAEE as substrates, optimum pH, and temperature stability are reported in this study. The effect of MMEA on the enzymatic reaction is examined as well. In an industrial application, immobilized enzymes can enhance stability over a broad range of temperature and pH. Therefore, choline oxidase was immobilized on CNBr‐activated Sepharose beads, and the effects of immobilization are reported in this study.

Facile and Green Synthesis of Highly Fluorescent Carbon Quantum Dots from Water Hyacinth for the Detection of Ferric Iron and Cellular Imaging.

Natural biomass is used for facile synthesis of carbon quantum dots (CQDs) with high fluorescence, owing to its abundance, low cost, and eco-friendliness. In this study, a bottom-up hydrothermal method was used to prepare CQDs from water hyacinth (wh) at a constant temperature of 180 °C for 12 h. The synthesized wh-CQDs had uniform size, amorphous graphite structure, high water solubility (containing multiple hydroxyl and carboxyl groups on the surface), excitation light-dependent characteristics, and high photostability. The results showed that the aqueous solution of CQDs could detect Fe3+ rapidly, sensitively, and highly selectively with a detection limit of 0.084 μM in the linear range of 0–330 μM, which is much lower than the detection limit of 0.77 μM specified by the World Health Organization. More importantly, because the wh-CQDs were synthesized without any additives, they exhibited low toxicity to Klebsiella sp. cells even at high concentrations. Moreover, wh-CQDs emitted bright blue fluorescence in Klebsiella sp. cells, indicating its strong penetrating ability. Correspondingly, the fluorescent cell sorting results also revealed that the proportion of cell internalization reached 41.78%. In this study, wh-CQDs derived from natural biomass were used as high-performance fluorescent probes for Fe3+ detection and Klebsiella sp. imaging. This study is expected to have great significance for the application of biomass carbon spots in the field of cellular imaging and biology.

Building blend from recycling acrylonitrile–butadiene–styrene and high impact-resistance polystyrene through dextro-glucose

As the constantly upgrading of electronic product, and the number of plastic shells of waste electronic products is also increasing sharply. Acrylonitrile-butadiene-styrene (ABS) and high impact-resistance polystyrene (HIPS) account for a large part, but ABS and HIPS not only have similar densities, but also have similar chemical properties, which make it difficult to separate ABS and HIPS. Therefore, the preparation of composite materials by blending waste ABS and waste HIPS is an important method to realize the high-value reuse of waste ABS and waste HIPS. In this work, d-glucose (d-Glucose) was used as a compatibilizing agent for the first time to modify recycling acrylonitrile-butadiene-styrene (rABS) and recycling high impact-resistance polystyrene (rHIPS) by melt blending. The d-Glucose has multiple hydroxyl groups, and it can react with the aging groups of butadiene in rABS/rHIPS to form ester groups, repairs broken molecular chains and improves compatibility between two phases to enhance the mechanical properties. The results show that the impact strength, tensile strength, flexural strength and storage modulus of the resulted rABS/rHIPS blend have been enhanced. When added the number of d-Glucose accounts for 5 wt% of the total components, the notched impact strength reaches 9.67 kJ/m2, which is 128% higher than that before modification. Compared with other researchers, not only the impact strength is greatly improved, but also the tensile strength and flexural strength are improved. The mechanisms for the enhancement is studied and discussed.

Sensitive Detection of 8‐Hydroxyquinoline in Cosmetics by Using a Poly(tannic acid)‐Modified Glassy Carbon Electrode

AbstractTannic acid (TA) as a natural plant polyphenol bearing multiple phenolic hydroxyl groups could cause considerable interactions with organic compounds. This work aims at detecting 8‐hydroxyquinoline (8‐HQ) based on poly (tannic acid) (PTA) by electropolymerization of TA on glassy carbon electrode (GCE). Owing to enhanced modified electrode surface area and interactions of PTA with 8‐HQ via hydrogen bonding and π‐π stacking, PTA/GCE exhibits electrocatalytic activity to 8‐HQ. Using Differential pulse voltammetry, PTA/GCE shows two linear plots with 8‐HQ concentrations from 0.5 to 5 μmol L−1 and 5 to 50 μmol L−1, the detection limit is 0.036 μmol L−1. The PTA modified electrode also shows great reproducibility and stability. The application of the sensor for real hair conditioner samples is demonstrated with satisfactory result.

Interfacial architecting of organic–inorganic hybrid toward mechanically reinforced, fire-resistant and smoke-suppressed polyurethane composites

Polyurethane (PU) composites integrated with outstanding fire retardancy, smoke suppression as well as ameliorated mechanical property is attractive, but remains a challenge. Here, we demonstrate the interfacial architecting of organic–inorganic hybrid (ACAPP) by reacting renewable chitooligosaccharide (COS) with ammonium polyphosphate (APP) and ammonium octamolybdate (AOM) via a one-pot, facile and eco-friendly approach. The ACAPP with multiple hydroxyl groups shows good compatibility and strong interfacial adhesion force with PU matrix due to the abundant covalent cross-linking points and hydrogen bonds networks. The incorporation of 15 wt% ACAPP enables the resultant PU composite to achieve a V-0 rating, a limiting oxygen index of 26.1%, 31.1% and 44.8% reduction in total heat release and total smoke production, respectively, far outdistancing conventional APP. The suppressed fire hazards mainly benefits from the synergy catalytic carbonization effect of ACAPP in condensed phase. Moreover, ACAPP reinforces the tensile strength of PU whilst retaining the decent ultimate elongation. This work may offer a referable exemplification for constructing green flame-retardant to balance high fire safety and mechanical properties.

Deep eutectic solvents with multiple hydroxyl sites for efficient and reversible absorption of SF6

Finding the adsorbents to efficiently and reversibly capture SF6 has important research significance. Most of the currently reported solid absorbents used to capture SF6 can have disadvantages such as difficult recovery and easy deactivation. To address this critical challenge, we here report an effective strategy to capture sulfur hexafluoride (SF6) using the hydroxyl-rich deep eutectic solvents (DESs) for the first time. The physical properties of as-prepared seven hydroxyl-rich DESs are systematically investigated, and the effects of structure of DESs, absorption temperature, pressure, and water content on absorption performance of SF6 also are inspected, respectively. In particular, ChCl-Gly (1:2) not only exhibits highest absorption capacity of SF6 with up to 0.1738 g SF6/g DES at 293.2 K and 1.0 bar, but also can be reused without significant decline in absorption capacity of SF6. In addition, the absorption mechanism study of SF6 is conducted by FTIR, NMR and DFT chemical calculations. The results suggest that the high absorption capacity of SF6 originates from the intermolecular hydrogen bonding of SF6 molecules and hydroxyl protons in DESs.

A Mechanistic Study of Wettability Alteration of Calcite as an Example of Carbonate Reservoirs Using Molecular Dynamics Simulation

Abstract It is common sense the wettability alteration in carbonate reservoirs stems from the oil–rock interactions; however, the exact oil component acting as the dominant role remains unclear. This study adopts molecular dynamics technology, takes {101¯4} calcite crystal surface as the mineral surface of carbonate reservoir, uses multiple single-component oils to characterize real crude oil, and conducts research on the wettability alteration of carbonate reservoirs. First, based on the chromatographic analysis results of a certain carbonate reservoir in the Middle East, the simulated oil is divided into polar and nonpolar components. Then, the Materials Studio software and the COMPASS force field were employed to study the natural wettability of the calcite surface, as well as the adsorption characteristic of different oil components and water on the surface of calcite. Results show that the surface of calcite in carbonate reservoirs is indeed water-wet under initial conditions, and the contact angle of calcite surface is equal to 68.47 deg ± 3.6 deg. However, when the crude oil component contains groups of hydroxyl functional group, especially the strongly polar component with multiple hydroxyl functional groups, such as glycerol (GLYC), will cause the originally water-wet calcite surface becomes oil-wet. The main reason for the GLYC component altering the wettability of the calcite surface is hydrogen bonding and Coulomb interaction. Moreover, the results of centroid displacement of nine oil components shown that besides the GLYC component, the rest of the eight components, including the polar component of nitrogen-containing functional groups (Indole), sulfur-containing functional groups (Benzothiophene), as well as five nonpolar components, all migrate away from the calcite surface.

Diversity-Oriented Synthesis Catalyzed by Diethylaminosulfur-Trifluoride-Preparation of New Antitumor Ecdysteroid Derivatives.

Fluorine represents a privileged building block in pharmaceutical chemistry. Diethylaminosulfur-trifluoride (DAST) is a reagent commonly used for replacement of alcoholic hydroxyl groups with fluorine and is also known to catalyze water elimination and cyclic Beckmann-rearrangement type reactions. In this work we aimed to use DAST for diversity-oriented semisynthetic transformation of natural products bearing multiple hydroxyl groups to prepare new bioactive compounds. Four ecdysteroids, including a new constituent of Cyanotis arachnoidea, were selected as starting materials for DAST-catalyzed transformations. The newly prepared compounds represented combinations of various structural changes DAST was known to catalyze, and a unique cyclopropane ring closure that was found for the first time. Several compounds demonstrated in vitro antitumor properties. A new 17-N-acetylecdysteroid (13) exerted potent antiproliferative activity and no cytotoxicity on drug susceptible and multi-drug resistant mouse T-cell lymphoma cells. Further, compound 13 acted in significant synergism with doxorubicin without detectable direct ABCB1 inhibition. Our results demonstrate that DAST is a versatile tool for diversity-oriented synthesis to expand chemical space towards new bioactive compounds.

Umpolung carbonyls enable direct allylation and olefination of carbohydrates.

Mother Nature has its own arts to build a vast number of carbohydrates; however, there is still a lack of tools for selective functionalization of native carbohydrates through C─C bond formation. Such a long-standing challenge for the synthetic community lies into the intrinsic problems related to the innate properties of carbohydrates, e.g., the ease to oligomerization or polymerization, the difficulty of chemoselectivity control in the presence of multiple hydroxyl groups, the great challenge to retain the multiple chiral centers during the transformation, etc. Here, by applying an umpolung strategy of carbohydrate carbonyls, we report a direct deoxygenative allylation and olefination of carbohydrates to tackle the abovementioned issues. The reaction is compatible with a wide range of natural carbohydrates, providing a direct synthetic method to use carbohydrates as multiple C-centered chiral synthons to achieve C─C bond cross-coupling reactions. Furthermore, the synthetic applicability is demonstrated by late-stage modifications of natural products and pharmaceutical derivatives.

Steam reforming of monohydric alcohols and polyalcohols: Influence of single or multiple hydroxyl group(s) on nature of the coke

Alcohols like ethanol and glycerol have been extensively investigated as potential feedstock for on-site hydrogen production by steam reforming. The varied number of hydroxyl group in the alcohols inevitably affects the reaction intermediates generated and eventually properties of coke formed. In this study, four alcohols (ethanol, ethylene glycol, 1-propanol and glycerol) with the single or multiple hydroxyl groups were steam reformed, focusing on the influence of the hydroxyl group on the properties of the coke. The research results showed that steam reforming of ethanol and glycerol produced more coke than that in steam reforming of 1-propanol or ethylene glycol, while the Ni/SBA-15 catalyst deactivated to a higher extent in steam reforming of ethylene glycol or glycerol with multiple hydroxyl group, due to the coke of varied properties. The coke produced by steam reforming of ethanol and 1-propanol contained more defective structures but more aromatic. However, the generated coke from the steam reforming of ethylene glycol and glycerol had more aliphatic structures, especially in that from ethylene glycol. On the other hand, the carbon nanotubes formed by the steam reforming of ethanol or 1-propanol had thin wall thickness and smooth surface, while that in steam reforming of ethylene glycol and glycerol had thick wall and very rough surface, resulting from the distinct reaction intermediates formed.

Multifunctional polyphenol-based silk hydrogel alleviates oxidative stress and enhances endogenous regeneration of osteochondral defects

In osteochondral defects, oxidative stress caused by elevated levels of reactive oxygen species (ROS) can disrupt the normal endogenous repair process. In this study, a multifunctional hydrogel composed of silk fibroin (SF) and tannic acid (TA), the FDA-approved ingredients, was developed to alleviate oxidative stress and enhance osteochondral regeneration. In this proposed hydrogel, SF first interacts with TA to form a hydrogen-bonded supramolecular structure, which is subsequently enzymatically crosslinked to form a stable hydrogel. Furthermore, TA had multiple phenolic hydroxyl groups that formed interactions with the therapeutic molecule E7 peptide for controlled drug delivery. In vitro investigations showed that SF-TA and SF-TA-E7 hydrogels exhibited a multitude of biological effects including scavenging of ROS, maintaining cell viability, and promoting the proliferation of bone marrow mesenchymal stem cells (BMSCs) against oxidative stress. The proteomic analysis indicated that SF-TA and SF-TA-E7 hydrogels suppressed oxidative stress, which in turn improved cell proliferation in multiple proliferation and apoptosis-related pathways. In rabbit osteochondral defect model, SF-TA and SF-TA-E7 hydrogels promoted enhanced regeneration of both cartilage and subchondral bone as compared to hydrogel without TA incorporation. These findings indicated that the multifunctional SF-TA hydrogel provided a microenvironment suitable for the endogenous regeneration of osteochondral defects.