One‐Pot Template‐Free Synthesis of Monodisperse Zinc Sulfide Hollow Spheres and Their Photocatalytic Properties

Little hollow! Monodisperse ZnS hollow nanospheres (see figure) of about 200 nm in size have been fabricated on a large scale by a hydrothermal method and they show good photocatalytic activity in the decolorization of an aqueous solution of rhodamine B under UV irradiation.

     

One‐Pot Template‐Free Synthesis of NaYF4 Upconversion Hollow Nanospheres for Bioimaging and Drug Delivery

Hollow‐structured nanomaterials with fluorescent properties are extremely attractive for image‐guided cancer therapy. In this paper, sub‐100 nm and hydrophilic NaYF₄ upconversion (UC) hollow nanospheres (HNSs) with multicolor UC luminescence and drug‐delivery properties were successfully prepared by a facile one‐pot template‐free hydrothermal route using polyetherimide (PEI) polymer as the stabilizing agent. XRD, SEM, TEM, and N₂‐adsorption/desorption were used to characterize the as‐obtained products. The growth mechanism of the HNSs has been systematically investigated on the basis of the Ostwald ripening. Under 980 nm excitation, UC emissions of HNSs can be tuned by a simple change of the concentration or combination of various upconverters. As a result, the PEI‐coated HNSs could be used as efficient probes for in vitro upconversion luminescence (UCL) cell imaging. Furthermore, a doxorubicin storage/release behavior and cancer‐cell‐killing ability investigation reveal that the product has the potential to be a drug carrier for cancer therapy.     

One‐Pot Self‐Templating Synthesis of Pt Hollow Nanostructures and Their Catalytic Properties for CO Oxidation

Nanoporous Pt hollow nanostructures with octahedral and hexagonal frame‐like morphologies were prepared by a novel one‐pot self‐templating route with no assistance from a preformed template or shape‐directing agent. The hexagonal frame‐like Pt hollow structures exhibited significantly enhanced catalytic activity toward CO oxidation reaction compared to the octahedral Pt hollow nanostructures due to the higher oxidation state of Pt.     

Template‐Free Synthesis of Hierarchical Vanadium‐Glycolate Hollow Microspheres and Their Conversion to V2O5 with Improved Lithium Storage Capability

Nanosheet‐assembled hierarchical V₂O₅ hollow microspheres are successfully obtained from V‐glycolate precursor hollow microspheres, which in turn are synthesized by a simple template‐free solvothermal method. The structural evolution of the V‐glycolate hollow microspheres has been studied and explained by the inside‐out Ostwald‐ripening mechanism. The surface morphologies of the hollow microspheres can be controlled by varying the mixture solution and the solvothermal reaction time. After calcination in air, hierarchical V₂O₅ hollow microspheres with a high surface area of 70 m² g^?1 can be obtained and the structure is well preserved. When evaluated as cathode materials for lithium‐ion batteries, the as‐prepared hierarchical V₂O₅ hollow spheres deliver a specific discharge capacity of 144 mA h g^?1 at a current density of 100 mA g^?1, which is very close to the theoretical capacity (147 mA h g^?1) for one Li⁺ insertion per V₂O₅. In addition, excellent rate capability and cycling stability are observed, suggesting their promising use in lithium‐ion batteries.     

One‐Pot Synthesis of Redox‐Responsive Polymers‐Coated Mesoporous Silica Nanoparticles and Their Controlled Drug Release

A versatile one‐pot strategy for the preparation of reversibly cross‐linked polymer‐coated mesoporous silica nanoparticles (MSNs) via surface reversible addition–fragmentation chain transfer (RAFT) polymerization is presented for the first time in this paper. The less reactive monomer oligo(ethylene glycol) acrylate (OEGA) and the more reactive cross‐linker N,N′‐cystaminebismethacrylamide (CBMA) are chosen to be copolymerized on the external surfaces of RAFT agent‐functionalized MSNs to form the cross‐linked polymer shells. Owing to the reversible cleavage and restoration of disulfide bonds via reduction/oxidation reactions, the polymer shells can control the on/off switching of the nanopores and regulate the drug loading and release. The redox‐responsive release of doxorubicin (DOX) from this drug carrier is realized. The protein adsorption, in vitro cytotoxicity assays, and endocytosis studies demonstrate that this biocompatible vehicle is a potential candidate for delivering drugs. It is expected that this versatile grafting strategy may help fabricate satisfying MSN‐based drug delivery systems for clinical application.

     

Metal‐Free One‐Pot Synthesis of Benzofurans

Ethyl acetohydroxamate was efficiently arylated with diaryliodonium salts at room temperature under transition‐metal‐free conditions. The obtained O‐arylated products were reacted in situ with ketones under acidic conditions to yield substituted benzo[b]furans through oxime formation, [3,3]‐rearrangement, and cyclization in a fast and operationally simple one‐pot fashion without using excess reagents. Alternatively, the O‐arylated products could be isolated or transformed in situ to aryloxyamines or O‐arylaldoximes. The methodology was applied to the synthesis of Stemofuran A and the formal syntheses of Coumestan, Eupomatenoid 6, and (+)‐machaeriol B.     

One‐Pot Synthesis and Electrocatalytic Properties of Pd@Pt Core‐Shell Nanocrystals with Tailored Morphologies

Pd@Pt core‐shell nanocrystals consisting of well‐defined Pd nanocube cores and dendritic Pt shells were prepared by a new facile aqueous one‐pot synthetic method. The prepared Pd@Pt nanocrystals exhibited efficient catalytic activity and stability toward methanol electrooxidation, and their catalytic function was highly dependent on their Pt shell thickness due to the different synergism between Pt and Pd.     

Seed‐Assisted,One‐Pot Synthesis of Hollow Zeolite Beta without Using Organic Structure‐Directing Agents

Hollow aluminosilicate zeolite beta was successfully synthesized by adding CIT‐6, that is, zincosilicate zeolite, which has the same topology as beta, as seeds to the Na‐aluminosilicate gel without the need for organic structure‐directing agents. One important factor in the successful organic structure‐directing agent (OSDA)‐free synthesis of hollow beta crystals is the solubility of the seed crystals in alkaline media. CIT‐6 was less stable than aluminosilicate zeolite beta in alkaline media and the solubility changed depending on whether the crystals were calcined or not. The hollow beta could be obtained by using the uncalcined CIT‐6 seed crystals. The volumes of intra‐crystalline voids were tuned by changing the reaction time and the initial gel compositions, such as the SiO₂/Al₂O₃ and Na₂O/SiO₂ ratios. We estimated that the intra‐crystalline voids were formed through the dissolution of the seed crystals, just after the crystal growth of new beta on the outer surface of the seeds. In addition, new crystal growth toward inside of the void was also observed by TEM. On the basis of the characterization data, such as chemical analysis, N₂‐adsorption/desorption measurements, and TEM observation, a formation mechanism of the intra‐crystalline voids is proposed and discussed.     

Catalyst‐Free One‐Pot Synthesis of Ketene Imines under Ultrasound Irradiation

An efficient and simple procedure for the synthesis of ketene imines via a one‐pot three‐component reaction of cyclohexyl isocyanide, diethyl acetylenedicarboxylate, and 1,4‐dihydropyridines under ultrasonic irradiation is described. The remarkable advantages are the simplicity of the experimental procedures, high yields, and short reaction times.     

Core‐shell structure microcapsules with dual pH‐responsive drug release function

We report dual pH‐responsive microcapsules manufactured by combining electrostatic droplets (ESD) and microfluidic droplets (MFD) techniques to produce monodisperse core (alginate)‐shell (chitosan) structure with dual pH‐responsive drug release function. The fabricated core‐shell microcapsules were size controllable by tuning the synthesis parameters of the ESD and MFD systems, and were responsive in both acidic and alkaline environment, We used two model drugs (ampicillin loaded in the chitosan shell and diclofenac loaded in the alginate core) for drug delivery study. The results show that core‐shell structure microcapsules have better drug release efficiency than respective core or shell particles. A biocompatibility test showed that the core‐shell structure microcapsules presented positive cell viability (above 80%) when evaluated by the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay. The results indicate that the synthesized core‐shell microcapsules were a potential candidate of dual‐drug carriers.     

One‐Pot Automated Synthesis of Quasi Triblock Copolymers for Self‐Healing Physically Crosslinked Hydrogels

The preparation of physically crosslinked hydrogels from quasi ABA‐triblock copolymers with a water‐soluble middle block and hydrophobic end groups is reported. The hydrophilic monomer N‐acryloylmorpholine is copolymerized with hydrophobic isobornyl acrylate via a one‐pot sequential monomer addition through reversible addition fragmentation chain‐transfer (RAFT) polymerization in an automated parallel synthesizer, allowing systematic variation of polymer chain length and hydrophobic–hydrophilic ratio. Hydrophobic interactions between the outer blocks cause them to phase‐separate into larger hydrophobic domains in water, forming physical crosslinks between the polymers. The resulting hydrogels are studied using rheology and their self‐healing ability after large strain damage is shown.

     

Self‐Assembled Hollow Polyaniline/Au Nanospheres Obtained by a One‐Step Synthesis

Self‐assembled hollow nanosphere composites of polyaniline and Au nanoparticles (PANI‐p‐TSA/Au) were chemically synthesized from solutions containing p‐toluenesulfonic acid (p‐TSA) with the addition of gold chloride trihydrate as the oxidant. The composite materials were characterized by SEM, TEM, and a range of spectroscopic methods. Spectroscopic characterizations confirmed that the polymeric product is a form of doped PANI, while electron diffraction and X‐ray diffraction showed that elemental Au was present in the PANI‐p‐TSA/Au nanocomposites. The room temperature electrical conductivity of the PANI‐p‐TSA/Au nanocomposites was two orders of magnitude greater than a PANI‐p‐TSA obtained in the presence of ammonium persulfate as the oxidant under the same conditions.

     

Ultrafine hydrogel fibers with dual temperature‐ and pH‐responsive swelling behaviors

Ultrafine hydrogel fibers that were responsive to both temperature and pH signals were prepared through the electrospinning of poly(N‐isopropylacrylamide) (PNIPAAm) and poly(acrylic acid) mixtures in dimethylformamide. Both the diameters (700 nm to 1.2 μm) and packing of the fibers could be controlled through changes in the polymer compositions and PNIPAAm molecular weights. These fibers were rendered water‐insoluble by the addition of either Na₂HPO₄ or poly(vinyl alcohol) (PVA) to the solution, followed by the heat curing of the fibers. The fibers crosslinked with Na₂HPO₄ swelled to 30–120 times in water; this was significantly higher than the swelling of those crosslinked with PVA. The PVA‐crosslinked hydrogel fibers, however, exhibited faster swelling kinetics; that is, they reached equilibrium swelling in less than 5 min at 25 °C. They were also more stable after 1 week of water exposure; that is, they lost less mass and retained their fibrous form better. All the hydrogel fibers showed a drastic increase in the swelling between pH 4 and 5. The PVA‐crosslinked hydrogel fibers exhibited distinct temperature‐responsive phase‐transition behavior of PNIPAAm, whereas the Na₂HPO₄‐crosslinked hydrogel fibers showed altered two‐stage phase transitions that reflected side‐chain modification of PNIPAAm. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6331–6339, 2004     

Transition‐Metal‐Free One‐Pot Synthesis of Biaryls from Grignard Reagents and Substituted Cyclohexanones

A new strategy for the construction of biaryls by a transition‐metal‐free process is presented. A sequence of a Grignard reaction, dehydration, and oxidative aromatization affords the desired products in a one‐pot fashion.     

One‐Pot Synthesis of Pyrimido[1,2‐a]benzimidazoles under Solvent‐Free Conditions

A series of pyrimido[1,2‐a]benzimidazoles were obtained from aldehydes, 2‐aminobenzimidazole and ethyl acetoacetate in good‐to‐excellent yields by a simple, mild, and efficient procedure utilizing N,N,N′,N′‐tetrabromobenzene‐1,3‐disulfonamide (TBBDA) and poly(N‐bromo‐N‐ethylbenzene‐1,3‐disulfonamide) (PBBS) as catalysts.     

Monodisperse superparamagnetic pH‐sensitive single‐layer chitosan hollow microspheres with controllable structure

Facile strategy was developed for the fabrication of the monodisperse superparamagnetic pH‐sensitive single‐layer chitosan (CS) hollow microspheres with controllable structure. The carboxyl group‐functionalized polystyrene microspheres prepared by soap‐free emulsion polymerization were used as the templates. After the Fe₃O₄ nanoparticles were in situ formed onto the surface of the templates, the single‐layer CS was self‐assembled and cross‐linked with glutaraldehyde subsequently. Then, the magnetic single‐layer CS hollow microspheres were obtained after the templates were removed. It was found that the feeding ratio of the monomer acrylic acid in the soap‐free emulsion polymerization had played an important role on the particle size and surface carboxyl group content of the templates, which determined the particle size and shell thickness of the magnetic single‐layer CS hollow microspheres in the proposed strategy. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Solvent‐Free One‐Pot Synthesis of Amidoalkyl Naphthols Catalyzed by Silica Sulfuric Acid

An efficient, inexpensive, and mild method for the synthesis of amidoalkyl naphthols, catalyzed by ‘silica sulfuric acid’ (SSA), was elaborated under solvent‐free conditions at room temperature. Various amidoalkyl naphthols were synthesized in high yields from aromatic or aliphatic aldehydes, α‐ or β‐naphthols, and amides or urea or thiourea.     

A Novel One‐Pot Synthesis of Substituted Quinolines

A synthesis of quinoline derivatives is described via reaction between ethyl bromopyruvate (=ethyl 3‐bromo‐2‐oxopropanoate), acetylenedicarboxylate, and isatin (=1H‐indole‐2,3‐dione) in the presence of NaH as a base. Also, these reactions were performed without ethyl bromopyruvate. The reaction in the presence of ethyl bromopyruvate provides regioselectively a quinoline with the ethyl ester group in 4‐position. In the absence of ethyl bromopyruvate, the reaction leads to functionalized quinolines with the same ester groups in 2‐, 3‐, and 4‐positions.