Polydopamine contained hydrogel nanocomposites with combined antimicrobial and antioxidant properties for accelerated wound healing.

Overproduction of reactive oxygen species (ROS) in infected wounds induces a tremendous inflammatory reaction to delay wound healing. To address this problem, we designed a multifunctional polyacrylamide/PVA-based hydrogel containing synthesized poly(1-glycidyl-3-butylimidazolium salicylate) (polyGBImSal) and fabricated polydopamine-coated polyphenolic nanosheet (PDA@PNS) for wound dressing. The PDA@PNS particles were designed to induce I) antioxidant and anti-inflammatory features through ROS-scavenging and II) cell adhesive properties by the existing polydopamine into the hydrogels. The poly(ionic liquid)-based polyGBImSal was designed to allocate effective hydrogel antimicrobial activity. The fabricated hydrogel nanocomposites showed excellent properties in the swelling ratio, cell adhesiveness, protein adsorption, and anti-inflammatory, proving their general performance for application in wound healing. Furthermore, these hydrogels showed high antimicrobial activity (over 95 %) against three common wound-infecting pathogenic microbes: Escherichia coli, Staphylococcus aureus, and Candida albicans. The healing process of full-thickness dermal wounds in rats was accelerated by applying hydrogel nanocomposites with 0.5 wt% of PDA@PNS and 28 wt% of polyGBImSal. The wound closure contraction attained full closure, reaching 100 %, after 14 days, contrasted with the control group employing commercial wound dressing (Tegaderm), which achieved a closure rate of 68 % within the equivalent timeframe. These results make these hydrogel nanocomposites promising candidates for multifunctional wound dressing applications.

Novel magnetic bimetallic AuCu catalyst for reduction of nitroarenes and degradation of organic dyes.

Herein, core-shell magnetic nanoparticles are modified with imidazolium-tagged phosphine and propylene glycol moieties and used for the stabilization of bimetallic AuCu nanoparticles. The structure and morphology of the prepared material are identified with SEM, TEM, XRD, XPS, atomic absorption spectroscopy, Fourier translation infrared spectroscopy, and a vibrating sample magnetometer. This hydrophilic magnetic bimetallic catalyst is applied in the reduction of toxic nitroarenes and reductive degradation of hazardous organic dyes such as methyl orange (MO), methyl red (MR), and rhodamine B (RhB), as well as in the degradation of tetracycline (TC). This magnetic AuCu catalyst indicated superior activity in all three mentioned reactions in comparison with its single metal Au and Cu analogs. This catalyst is recycled for 17 consecutive runs in the reduction of 4-nitrophenol to 4-aminophenol without a significant decrease in catalytic activity and recycled catalyst is characterized.

Stabilized Palladium Nanoparticles from Bis-(N-benzoylthiourea) Derived-PdII Complexes as Efficient Catalysts for Sustainable Cross-Coupling Reactions in Water.

Stable palladium (II) complexes, incorporating a double (N-benzoylthiourea) arrangement bonded to a complex heterocyclic scaffold, are used as precursors of catalytic species able to promote Suzuki-Miyaura, Mizoroki-Heck, Hiyama, Buchwald-Hartwig, Hirao and Sonogashira-Hagihara cross-coupling transformations in water. These sustainable processes are chemoselective and very versatile. The nanoparticles responsible for these catalytic reactions were analyzed and studied. Their usefulness is demonstrated after several tests and analyses. The heterogeneous character of this species in water was also confirmed.

Palladium nanoparticles supported on ionic liquid and glucosamine-modified magnetic iron oxide as a catalyst in reduction reactions.

A magnetic nanocomposite comprising imidazolium ionic liquid and glucosamine is successfully synthesized and used for stabilization of Pd nanoparticles. This new material, Fe3O4@SiO2@IL/GA-Pd, is fully characterized and applied as a catalyst in the reduction of nitroaromatic compounds to desired amines at room temperature. Also, the reductive degradation of organic dyes such as methylene blue (MB), methyl orange (MO), and rhodamine B (RhB) is studied and compared with another previous publications. The survey of the stabilization of the palladium catalytic entities is described demonstrating the separation ability and recycling of them. In addition, TEM, XRD, and VSM analyses of the recycled catalyst confirmed its stability.

Gold and palladium supported on an ionic liquid modified Fe-based metal-organic framework (MOF) as highly efficient catalysts for the reduction of nitrophenols, dyes and Sonogashira-Hagihara reactions.

Two supported noble metal species, gold and palladium anchored on an ionic liquid-modified Fe-based metal-organic framework (MOF), were successfully synthesized and characterized by FT-IR, XRD, TEM, XPS, SEM, EDX, and elemental mapping. The ionic liquid post-modified MOF was used for anchoring Au or Pd at ppm levels, and the resulting materials were employed as catalysts in the reduction of nitrophenol isomers, dyes, and Sonogashira-Hagihara reactions. Using the Au@Fe-MOF-IL catalyst, reduction of nitrophenol isomers, as well as the reductive degradation of dyes, e.g., methylene blue (MB), methyl orange (MO), and methyl red (MR) were performed efficiently in water. On the other hand, Pd@Fe-MOF-IL was used as an effective catalyst in the Sonogashira-Hagihara coupling reaction of aryl iodides and bromides using very low amounts of Pd. These catalysts were recycled and reused for several runs without deteriorating remarkably in catalytic performance.

Exploring Unusual Effects of the Ring Substituents in the Type II Reaction with TD-DFT and DFT.

The type II photoelimination reactions are important in biological systems. The different roles played by ring substituents are often not obvious from quantum yields for product formation and the rate constant for hydrogen abstraction is quite low (<107  s-1 ), but Hautala (Tetrahedron Lett. 1977, 18, 2499-2502) reported unusual effects of the nitro substituent in aryl ketones. They reported the first examples of such and discuss for another role played by the nitro group. They determined an upper limit of less than 2 × 10-5 to the quantum yield for formation of nitro substituent. They hypothesized the carbonyl localized state may be populated with high quantum efficiency, rapid deactivation occurs to populate the lower lying nitro localized state. We focus on the case where the theoretical studies are of great importance and indispensable, such as resolving the debate on the stepwise and concerted mechanism of hydrogen abstraction. Our proposed new mechanisms for 2-ethoxy-1-phenylethanone are based on the energy, HOMO-LUMO, dipole moments, etc. We provide modifications to experimentally proposed mechanisms or completely new mechanism with Hammett, synchronicity, singlet fission and relative rate equations to explain successfully the previous result. At the end, we show why an unusual effect of the nitro substituent exists in it.

Synergistic Effects of ppm Levels of Palladium on Natural Clinochlore for Reduction of Nitroarenes.

Augmenting the modified naturally occurring clay clinochlore with ppm amounts of palladium leads to a new and very effective reagent for the reduction of numerous aromatic nitro species. When palladium nanoparticles are supported on pyridyltriazole-modified clinochlore, iron within clinochlore acts synergistically with palladium to catalyze the reduction of a wide variety of nitroarenes at room temperature in aqueous media. Based on E-factor calculations, the catalyst system is found to be in line with green chemistry standards and can be recycled up to five times.

Palladium Nanoparticles on a Creatine-Modified Bentonite Support: An Efficient and Sustainable Catalyst for Nitroarene Reduction.

Creatine as the nitrogen-rich, green and cheap compound is used for modification of natural bentonite and the resulting material is employed for the stabilization of Palladium nanoparticles having an average diameter of 3 nm. This new material bento-crt@Pd is characterized using different techniques such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), solid state UV-vis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and energy-dispersive X-ray spectroscopy (EDX). This green catalyst promotes efficient reduction of aromatic nitro compounds in aqueous media. By using this catalyst nitroarenes having electron donating as well as electron withdrawing groups were reduced efficiently to their corresponding amines at room temperature. The catalyst can be recycled seven times and the reused catalyst was characterized by TEM and XPS.

Gold Nanoparticles Supported on Imidazole-Modified Bentonite: Environmentally Benign Heterogeneous Catalyst for the Three-Component Synthesis of Propargylamines in Water.

Gold nanoparticles supported on imidazole-modified bentonite, Bent@Im@Au NPs, has been developed for the first time as an effective heterogeneous catalyst for the synthesis of propargylamines under mild reaction conditions in water at a loading of 0.07 mol % of Au. Various techniques such as X-ray diffraction, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, and element mapping by scanning electron microscopy were used to determine the physicochemical properties of the catalysts. The new gold catalyst was found to be highly active providing high to excellent yields of A3 coupling products via the reactions of various aldehydes, having electron-withdrawing as well as electron-donating substituents, with different amines and alkynes. The catalysts can be easily recovered and reused without significant loss of activity and the recycled catalyst was characterized.

Assemblies of Copper Ferrite and Palladium Nanoparticles on Silica Microparticles as a Magnetically Recoverable Catalyst for Sonogashira Reaction under Mild Conditions.

Copper ferrite and palladium nanoparticles assembled on silica microparticles are prepared successfully and characterized by scanning electron microscopy, transmission electron microscopy, electron-dispersive X-ray analysis, X-ray diffraction, thermogravimetric analysis, atomic absorption spectroscopy, and infrared studies. The catalyst is applied effectively for the Sonogashira coupling reaction of aryl iodides and bromides under heterogeneous and phosphine-free reaction conditions. The reactions proceed at 50 °C with a low loading of palladium catalyst. The magnetically recoverable catalyst is recycled successfully for five consecutive runs with very small drops in catalytic activity.

One-Pot Preparation of Propargylamines Catalyzed by Heterogeneous Copper Catalyst Supported on Periodic Mesoporous Organosilica with Ionic Liquid Framework.

Copper supported on periodic mesoporous organosilica (PMO) with alkylimidazolium frameworks is a highly efficient and recoverable catalyst for the preparation of propargylamines through the three-component coupling reaction of aldehydes, alkynes, and amines. The new catalyst is characterized using N2 adsorption/desorption analysis, transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT-IR), and elemental analysis. The catalyst is easily recovered by a simple filtration process and subsequently reused in the seven reaction cycles without any loss of catalytic activity.

Highly efficient three-component coupling reaction catalyzed by gold nanoparticles supported on periodic mesoporous organosilica with ionic liquid framework.

A novel gold nanoparticle supported periodic mesoporous organosilica with alkylimidazolium framework, Au@PMO-IL, was shown to be a highly active and recyclable catalyst for three-component coupling reaction of aldehyde, alkyne and amine to give the corresponding propargylamine.