Bone morphogenetic protein (BMP)-modified graphene oxide-reinforced polycaprolactone-gelatin nanofiber scaffolds for application in bone tissue engineering.

In this study, blend nanofibrous scaffolds were electrospun from polycaprolactone/gelatin (PCL/Gel) blend solutions reinforced by bone morphogenetic protein (BMP)-modified graphene oxide (GO). SEM results showed that uniform and bead-less nanofibers with 270 nm average diameter were obtained from electrospun of PCL/Gel blend solutions. Tensile strength test and contact angle measurement demonstrated that addition of PCL led to higher mechanical and physical properties of the resulting nanofibers. The addition of PCL as well as GO in the blend supports the suitable mechanical strength in the body media. The loading of BMP-modified graphene in the Gel/PCL structure caused the formation of nanofibrous substrate with great resemblance to bone tissue. Gel/PCL-G hybrid nanofibers revealed good biocompatibility in the presence of human osteosarcoma cells, and no trace of cellular toxicity was observed. The cells grown on the scaffolds exhibited a spindle-like and broad morphology and almost uniformly covered the entire nanofiber scaffold. Gel/PCL nanofibers reinforced by graphene oxide-immobilized bone morphogenetic protein was prepared as a promising safe and biocompatible nanofiber with high antibacterial activity for bone tissue engineering.

Retraction: Bis-salophen palladium complex immobilized on Fe3O4@SiO2 nanoparticles as a highly active and durable phosphine-free catalyst for Heck and copper-free Sonogashira coupling reactions.

Retraction of 'Bis-salophen palladium complex immobilized on Fe3O4@SiO2 nanoparticles as a highly active and durable phosphine-free catalyst for Heck and copper-free Sonogashira coupling reactions' by Ali Reza Sardarian et al., Dalton Trans., 2019, 48, 3132-3145, https://doi.org/10.1039/C9DT00060G.

Transfer hydrogenation of nitroarenes using cellulose filter paper-supported Pd/C by filtration as well as sealed methods.

A reductive filter paper for selective nitro reduction has been prepared by modification of a pristine cellulose filter paper by Pd/C nanoparticles, as a portable catalyst. The reaction was performed in two different set-ups including (i) filtration and (ii) sealed systems, in the presence of ammonium formate and ex situ generated hydrogen gas reducing agents, respectively. In the sealed system in the presence of H2 gas, the halogenated nitroarenes were completely reduced, while in the filtration system, different derivatives of the nitroarenes were selectively reduced to aryl amines. In both systems, the reduction of nitroarenes to aryl amines was performed with high efficiency and selectivity, comparable to a heterogeneous system. Reaction parameters were comprehensively designed using Design Expert software and then studied. The properties of the catalytic filter paper were studied in detail from the points of view of swellability, shrinkage, reusability, and stability against acidic, alkaline, and oxidative reagents.

Catalytic filtration: efficient C-C cross-coupling using Pd(II)-salen complex-embedded cellulose filter paper as a portable catalyst.

A new approach has been developed for environmentally friendly C-C cross-coupling reactions using bi-functional Pd(ii)-salen complex-embedded cellulose filter paper (FP@Si-PdII-Salen-[IM]OH). A Pd(ii)-salen complex bearing imidazolium [OH]-moieties was covalently embedded into a plain filter paper, then used as an efficient portable catalyst for the Heck, Suzuki, and Sonogashira cross-coupling reactions under environmentally friendly conditions via the filtration method. The catalytic filter paper properties were studied by EDX, XPS, TGA, ATR, XRD, and FESEM analyses. The reactions were catalyzed during reactants' filtration over the catalytic filter paper. The modified filter paper was set up over a funnel and the reactants were passed through the catalytic filter paper several times. The effect of reaction parameters including loading of Pd(ii)-salen complex, temperature, solvent, and contact time were carefully studied and also the optimal model of conditions was presented by the design expert software. High to excellent yields were obtained for all C-C coupling types with 5 to 8 filtration times. Under optimal conditions, all coupling reactions showed high selectivity and efficiency. Another advantage of the modified filter paper was its stability and reusability for several times with preservation of catalytic activity and swellability.

Metal- and Solvent-Free Transesterification and Aldol Condensation Reactions by a Homogenous Recyclable Basic Ionic Liquid Based on the 1,3,5-Triazine Framework.

A new recyclable basic ionic liquid was introduced as an efficient catalyst for aldol condensation and transesterification reactions under environmentally friendly conditions. The catalyst was prepared based on methyl imidazolium moieties bearing hydroxide counter anions via the Hofmann elimination on a 1,3,5-triazine framework. The ionic liquid with two functionalities including anion stabilizer and high basicity, was used as an efficient catalyst for aldol condensation as well as transesterification reaction of a variety of alkyl benzoates. All reactions were performed in the absence of any external reagent, co-catalyst, or solvent, in line with environmental protection. The kinetics isotope effect (KIE) was conducted for the transesterification reaction to elucidate the mechanism and rate determining step (RDS). It worth noted that, the homogeneous catalyst could be recycled from the reaction mixture and reused for several consecutive runs with insignificant drop of basicity and conversion.

Efficient reduction of nitro compounds and domino preparation of 1-substituted-1H-1,2,3,4-tetrazoles by Pd(ii)-polysalophen coated magnetite NPs as a robust versatile nanocomposite.

A new, versatile, and green methodology has been developed for the efficient NaBH4-reduction of nitroarenes as well as the domino/reduction MCR preparation of 1-substituted-1H-1,2,3,4-tetrazoles using Pd(ii)-polysalophen coated magnetite NPs as an efficient heterogeneous magnetically recyclable nanocatalyst. Polysalophen was firstly prepared based on a triazine framework with a high degree of polymerization, then coordinated to Pd ions and, finally, the resulting hybrid was immobilized on magnetite NPs. The catalyst was characterized by various instrumental and analytical methods, including GPC, DLS, N2 adsorption-desorption, TGA, VSM, TEM, HRTEM, EDX, XPS, XRD, and ICP analyses. The catalyst possesses dual-functionality including the reduction of nitroarenes and the construction of tetrazole rings all in one step via a domino protocol. High to excellent yields were obtained for both nitro reduction and the direct preparation of 1-substituted-1H-1,2,3,4-tetrazoles from nitro compounds. Insight into the mechanism was conducted by XPS in situ as well as DLS in situ along with several control experiments. Recyclability of the catalyst was studied for 6 consecutive runs along with metal leaching measurements in each cycle.

Fe3O4@Sap/Cu(ii): an efficient magnetically recoverable green nanocatalyst for the preparation of acridine and quinazoline derivatives in aqueous media at room temperature.

Saponin, as a green and available phytochemical, was immobilized on the surface of magnetite nanoparticles then doped with Cu ions (Fe3O4@Sap/Cu(ii)) and used as an efficient nanocatalyst for the synthesis of quinazoline and acridine derivatives, due to their high application and importance in various fields of science. Different spectroscopic and microscopic techniques were used for the catalyst characterization such as FT-IR, XRD, FE-SEM, EDX, TEM, TGA, VSM, BET, DLS, CV, and XPS analyses. All characterization data were correlated with each other so that the structure of the catalyst was accurately characterized. The reactions were performed in the presence of a low amount of Fe3O4@Sap/Cu(ii) (0.42 mol%) as a green catalyst in water over a short period of time. The results show well the effective role of saponin in solving the problem of mass transfer in aqueous medium, which is the challenge of many organic reactions in aqueous medium and in the presence of heterogeneous medium. High catalytic activity was found for the catalyst and high to excellent efficiency was obtained for all quinazoline (68-94% yield) and acridine (66-97% yield) derivatives in short reaction times (less than 1 hour) under mild reaction conditions in the absence of any hazardous or expensive materials. There is not any noticeable by-product found whether for acridine or quinazoline derivatives, which reflects the high selectivity. Two reasonable mechanisms were proposed for the reactions based on observations from control experiments as well as literature reports. The catalyst could be easily recovered magnetically for at least six consecutive runs with insignificant reactivity loss.

Ni/Pd-catalyzed Suzuki-Miyaura cross-coupling of alcohols and aldehydes and C-N cross-coupling of nitro and amines via domino redox reactions: base-free, hydride acceptor-free.

Domino oxidation-Suzuki-Miyaura cross-coupling of benzyl alcohols with phenylboronic acid and domino reduction-C-N cross-coupling of the nitro compounds with aryl halides were carried out using a strong Ni/Pd bimetallic redox catalyst. The catalyst bearing a copolymer with two Ni/Pd coordinated metals in porphyrin (derived from demetalated chlorophyll b) and salen-type ligands, and pyridine moiety as a base functionality all immobilized on magnetite NPs was synthesised and characterized. The domino oxidation cross-coupling reaction was accomplished under molecular O2 in the absence of any hydride acceptor or/and base. Also, the domino reduction C-N cross-coupling reaction was performed in the presence of NaBH4 without the need for any base and co-reductant. This multifunctional catalyst gave moderate to good yields for both coupling reactions with high chemoselectivity. A wide investigation was conducted to determine its mechanism and chemoselectivity.

A Co-Cu bimetallic magnetic nanocatalyst with synergistic and bifunctional performance for the base-free Suzuki, Sonogashira, and C-N cross-coupling reactions in water.

A novel magnetically recyclable bimetallic catalyst was prepared by anchoring imidazolium moiety and PEG chains on Fe3O4 NPs and named as Fe3O4@PEG/Cu-Co. It was found to be a powerful catalyst for the Sonogashira, Suzuki, and C-N cross-coupling reactions in water as a green solvent without the need for any external base. Fe3O4@PEG/Cu-Co was well characterized with FT-IR, FE-SEM, TEM, VSM, EDX, ICP, UV-visible, CV, and XPS analyses. Optimum ranges of parameters such as time, temperature, and amount of catalyst were investigated by Design-Expert 10.0.7 software for C-C Suzuki, Sonogashira, and C-N cross-coupling reactions to find the optimum conditions. The catalyst was compatible with a variety of aryl halides and N-arenes and gave favorable coupling products with good to high yields for all of them. Hot filtration and Hg poisoning tests involving the nanocatalyst revealed the stability, low metal leaching, and heterogeneous nature of the catalyst. Reaction mechanisms were proposed by study of the UV-visible spectra in situ as well as hydroquinone tests during the progress of reactions. In situ XPS analysis was also used to study the reaction mechanism. To prove the synergistic performance of Co and Cu in the catalyst, its various homologues were synthesized and applied to a model reaction separately, and then their catalytic activities were investigated. Finally, the catalyst could be recovered from the reaction mixture simply, and reused for several cycles with a minimum loss in catalytic activity and performance.

Bis-salophen palladium complex immobilized on Fe3O4@SiO2 nanoparticles as a highly active and durable phosphine-free catalyst for Heck and copper-free Sonogashira coupling reactions.

New Fe3O4@SiO2 core-shell superparamagnetic nanoparticles functionalized by a bis-salophen Schiff base Pd complex were synthesized and employed as an efficient magnetic nanocatalyst in the Heck and Sonogashira cross coupling reactions. The synthesized nanostructures were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), dynamic light scattering (DLS), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), elemental analysis (CHN), cyclic voltammetry (CV), Brunauer-Emmett-Teller analysis (BET), and UV-vis spectroscopy. The morphology and size of the nanoparticles were investigated by FE-SEM and TEM analyses. Furthermore, the magnetic properties of the catalyst were investigated by VSM analysis. The loading content and leaching amounts of palladium on the catalyst were measured by inductively coupled plasma (ICP) analysis. Also, the thermal behavior of this magnetic heterogeneous catalyst was studied using a TGA instrument. This heterogeneous catalytic system showed a good performance in the coupling of aryl halides with alkynes (Sonogashira reaction) as well as aryl halides with alkene derivatives (Heck reaction). High to excellent yields were achieved for these C-C coupling reactions. The catalyst can be simply separated from the reaction media by an external magnet and reused for eight consecutive runs without any significant loss of activity. Finally, the kinetics of the reactions were studied in this work.

The CuFe2O4@SiO2@ZrO2/SO4 2-/Cu nanoparticles: an efficient magnetically recyclable multifunctional Lewis/Brønsted acid nanocatalyst for the ligand- and Pd-free Sonogashira cross-coupling reaction in water.

Herein, the synthesis and application of copper-incorporated sulfated zirconium oxide supported on CuFe2O4 NPs (CuFe2O4@SiO2@ZrO2/SO4 2-/Cu NPs) as a novel Lewis/Brønsted acid nanocatalyst were studied for the Sonogashira C-C cross-coupling reaction. The fabricated CuFe2O4@SiO2@ZrO2/SO4 2-/Cu catalyst exhibited efficient activity for a large variety of aryl iodides/bromides and, most importantly, aryl chlorides in water and in the presence of NaOH as a base in short reaction times. The catalyst was fully characterized by FTIR, TG-DTG, VSM, XRD, EDX, FE-SEM and TEM analyses. A synergetic effect could be considered to have arisen from the various Lewis acid and Brønsted acid sites present in the catalyst. The efficient incorporation of copper into zirconia provided a robust highly stable hybrid, which prevented any metal leaching, whether from the magnetite moiety and/or Cu sites in the reaction mixture. Moreover, the catalyst was successfully recovered from the mixture by a simple external magnet and reused for at least 9 consecutive runs. Zero metal leaching, stability, consistency with a variety of substrates, fast performance, cost-effectiveness, environmental friendliness, and preparation with accessible and cheap materials are some of the advantages and highlights of the current protocol.

Melamine-Schiff base/manganese complex with denritic structure: An efficient catalyst for oxidation of alcohols and one-pot synthesis of nitriles.

Efficient and selective oxidation of alcohol to the corresponding carbonyl and/or nitrile was carried out by a new water-soluble melamine-based dendritic Mn(III) complex (Melamine-Mn (III)-Schiff base complex) in the presence of 2,4,6-trichloro-1,3,5-triazine (TCT) and O2 at room temperature. Also, the oxidation of amine to the corresponding nitrile with high selectivity and conversion was performed at room temperature using the current method and high amounts of turnover frequencies (TOFs) were obtained for reactions. This system was also applicable for direct preparation of oxime through oxidation of alcohol. The catalyst was characterized by Fourier-transform infrared (FTIR), ultraviolet-visible (UV-Vis), thermogravimetric analysis (TGA), energy-dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), CHN and inductively coupled plasma (ICP) analyses. Also, oxidation/reduction behavior of the catalyst was studied by cyclic voltammetry (CV). Moreover, chemoselectivity of the catalyst was discussed with various combinations. The water-soluble catalyst could be recycled from the reaction mixture and reused for several times with a very low losing in efficiency. The recovered catalyst was also investigated with various analyses. Finally, gram scale preparation of nitrile was evaluated by present method.