Facile Solution-phase Synthesis Research Articles

Multivalency-induced structural variations of 2D selenium nanosheets: facile solution-phase synthesis and optical properties.

The structural stability of two-dimensional (2D) phases derived from bulk selenium (Se) is intrinsically rooted in the multivalent nature of the material. The emergence of 2D Se, as its morphology evolves from 1D to 2D, was initially inspired by theoretical predictions of various quasi-stable structural phases of 2D Se. Here, we report a facile liquid-phase synthesis of free-standing few-layer selenium nanosheets (SeNS) employing a simple magnetic stirring of their bulk counterpart in N-methyl pyrrolidone (NMP). The synthesized SeNS possess lateral dimensions ranging from several hundreds of nanometers to a few microns, with a minimum thickness of ∼1 nm. High-resolution transmission electron microscopy reveals the existence of α- and β-selenene. Fourier transform infrared analysis suggests that the inherent surface/edge functionalization of 2D SeNS by NMP enhances their dispersion stability. The UV-vis-NIR absorption spectrum of SeNS exhibits a shoulder peak at 330 nm, attributed to surface/edge functionalization, and multiple peaks across the vis-NIR region, stemming from size quantization effects. The functionalized selenium nanosheets generate photoluminescence that spans the blue-green range, while the size quantization of SeNS leads to green-orange luminescence. The non-linear optical studies following Z-scan experiments with an open aperture revealed reverse saturable absorption (RSA) and strong optical limiting in 2D SeNS under 532 nm, 10 ns laser pulses. Notably, a transition from RSA to saturable absorption (SA) has also been observed in samples stirred over an extended period. In this perspective, the results illustrate the first experimental realization of free-standing multivalent 2D selenium in allotropic forms with unique optical properties.

Modular Synthesis of Trifunctional Peptide-oligonucleotide Conjugates via Native Chemical Ligation.

Cell penetrating peptides (CPPs) are being increasingly used as efficient vectors for intracellular delivery of biologically active agents, such as therapeutic antisense oligonucleotides (ASOs). Unfortunately, ASOs have poor cell membrane permeability. The conjugation of ASOs to CPPs have been shown to significantly improve their cellular permeability and therapeutic efficacy. CPPs are often covalently conjugated to ASOs through a variety of chemical linkages. Most of the reported approaches for ligation of CPPs to ASOs relies on methodologies that forms non-native bond due to incompatibility with in-solution phase conjugation. These approaches have low efficiency and poor yields. Therefore, in this study, we have exploited native chemical ligation (NCL) as an efficient strategy for synthesizing CPP-ASO conjugates. A previously characterized CPP [ApoE(133–150)] was used to conjugate to a peptide nucleic acid (PNA) sequence targeting human survival motor neuron-2 (SMN2) mRNA which has been approved by the FDA for the treatment of spinal muscular atrophy. The synthesis of ApoE(133–150)-PNA conjugate using chemo-selective NCL was highly efficient and the conjugate was obtained in high yield. Toward synthesizing trifunctional CPP-ASO conjugates, we subsequently conjugated different functional moieties including a phosphorodiamidate morpholino oligonucleotide (PMO), an additional functional peptide or a fluorescent dye (Cy5) to the thiol that was generated after NCL. The in vitro analysis of the bifunctional CPP-PNA and trifunctional CPP-(PMO)-PNA, CPP-(peptide)-PNA and CPP-(Cy5)-PNA showed that all conjugates are cell-permeable and biologically active. Here we demonstrated chemo-selective NCL as a highly efficient and superior conjugation strategy to previously published methods for facile solution-phase synthesis of bi-/trifunctional CPP-ASO conjugates.

Solution-phase synthesis of CsPbI3 nanowire clusters via polymer-induced anisotropic growth and self-assembly.

A facile solution-phase synthesis of black γ-phase CsPbI3 nanowire clusters was developed using poly(methyl methacrylate) (PMMA) as surfactant. PMMA was found to efficiently retard the crystal growth, thereby inducing anisotropic growth for formation of the nanowire structure, while the intermolecular hydrogen bonds of PMMA act as a driving force for self-assembly of the nanowires.

Morphology, microstructure and magnetic properties of Co2FeAl alloy nanostructures prepared at low temperature

Here we report a facile solution-phase synthesis of Co2FeAl alloy nanostructures by controlling the reaction temperatures and reaction times. The use of Teflon autoclave ensured the formation of pure Co2FeAl alloy nanostructures even at a low reaction temperature of 60 °C. X-ray diffraction analysis confirmed the formation of good crystalline Co2FeAl alloy with average grain size of about 20–30 nm. Scanning electron microscope observations showed the evolution of Co2FeAl alloy nanostructures from cluster flower nanostructure to layered columnar nanostructure. Magnetic investigations showed high saturation magnetization of 189.2 emu/g and low coercivity of 23 Oe of Co2FeAl alloy nanostructures at 150 °C. These Co2FeAl alloy nanostructures with special structure morphologies and good soft magnetic properties have great potential in some industry fields.

Ag nanoparticle-decorated biscuit-like Bi24O31Cl10 hierarchical microstructure composed of ultrathin nanoflake with outstanding photocatalytic activity

Fabrication of noble-metal nanoparticle decorated hierarchical heterostructure photocatalyst composed of ultrathin nanoflake can be considered as one of the most effective approach for enhancing the photocatalytic performance due to its unique micro-scale structure and functional combination. Therefore, we report the successful preparation of Ag nanoparticle-decorated biscuit-like Bi24O31Cl10 hierarchical microstructure through a facile solution-phase synthesis route. Experiment indicated that the Bi24O31Cl10 product was comprised of ultrathin nanoflake with thickness of 5–10 nm. After introducing Ag nanoparticle, the as-obtained Ag-Bi24O31Cl10 nanocomposite exhibited improved photocatalytic performance for the decolorization of rhodamine B in comparison to pure Bi24O31Cl10 sample. The amount of Ag in the heterostructure photocatalyst significantly influenced the photocatalytic efficiency, and 4 wt% Ag exhibited the best photocatalytic performance. In addition, an enhanced mechanism of photodegradation activity over Ag nanoparticle-decorated biscuit-like Bi24O31Cl10 hierarchical microstructure was proposed.

Synthesis and characterization of a mesoporous and three dimensional N-doped graphene structure via the Couette-Taylor flow and hydrothermal method

In this study, graphite oxide was successfully synthesized from bulk graphite flakes using a Couette-Taylor flow reactor. A high yield (∼93%) of single-layer and few-layer graphene oxide sheets was achieved in this study within a reaction time of one hour by optimizing the conditions. The graphite oxide was effectively exfoliated using the Taylor vortex flow with shearing stress. The degree of oxidation and the graphite oxide morphology were then studied. In addition, mesoporous and three-dimensional nitrogen-doped graphene structures were prepared via graphene oxide sheets and facile solution phase synthesis followed by thermal treatment. The nitrogen in the pyrrolidone ring of PVP was decomposed and incorporated into the carbon network, including pyridinic-N and graphitic-N. Furthermore, the mesoporous and three-dimensional Ni1.5Co1.5[Co(CN)6]2 Prussian blue analogue (PBA) and NiCo sulfides/N-doped graphene hybrid composite structures were successfully demonstrated via facile hydrothermal method.

Solvent-induced controllable synthesis of recyclable Ag2CO3 catalysts with enhanced visible light photocatalytic activity

The quest for cost-effective environmental remediation has motivated the research for highly efficient and stable photocatalysts capable of degrading pollutants under visible-light illumination. Ag-based visible-light-responsive photocatalysts demonstrate alluring properties and applications in the elimination of organic pollutants in wastewater, however they often suffer from inherent photo-corrosion under illumination. Herein, we report the facile solution-phase synthesis of silver carbonate (Ag2CO3) microcrystals with varied morphological features in different solvents. The size and morphology of Ag2CO3 materials can be tuned on the basis of varying types and ratios of solvents. The specific synthetic method allows the orientation controllable growth of Ag2CO3 microcrystals with variable length-to-diameter ratios, with the surface harvesting more solar energy, and the photocatalyst suppressing the electron-hole recombination. The enhancement in both the photocatalytic activity and photostability of Ag2CO3 catalysts is evident when AgNO3 and NaHCO3 are employed as stabilizers. Operating in the presence of 0.02M stabilizer, the photocatalyst demonstrates highly efficient and robust degradation performance of higher than 95% in 5 successive times towards typical organic dye rhodamine B (RhB). Active holes and reactive oxygen-containing superhydroxyl radicals (·O2−) are determined by trapping experiments to be the main species responsible for improved photocatalytic performance. This work provides new insights into the development of high-performance, recyclable Ag-based photocatalytic materials for energy and environmental applications.

The release of hydrogen from ammonia borane over copper/hexagonal boron nitride composites

Facile solution-phase synthesis of copper nanoparticles dispersed on h-BNviaa solvothermal method is proposed for hydrolytic dehydrogenation of ammonia borane.

Design of Advanced MnO/N-Gr 3D Walls through Polymer Cross-Linking for High-Performance Supercapacitor.

Three-dimensional, vertically aligned MnO/nitrogen-doped graphene (3D MnO/N-Gr) walls were prepared through facile solution-phase synthesis followed by thermal treatment. Polyvinylpyrrolidone (PVP) was strategically added to generate cross-links to simultaneously form 3D wall structures and to incorporate nitrogen atoms into the graphene network. The unique wall features of the as-prepared 3D MnO/N-Gr hybirdes provide a large surface area (91.516 m(2) g(-1)) and allow for rapid diffusion of the ion electrolyte, resulting in a high specific capacitance of 378 F g(-1) at 0.25 A g(-1) and an excellent charge/discharge stability (93.7% capacity retention after 8000 cycles) in aqueous 1 m Na2 SO4 solution as electrolyte. Moreover, the symmetric supercapacitors that were rationally designed by using 3D MnO/N-Gr hybrids exhibit outstanding electrochemical performance in an organic electrolyte with an energy density of 90.6 Wh kg(-1) and a power density of 437.5 W kg(-1).

Swift synthesis, functionalization and phase-transfer studies of ultrastable, visible light emitting oleate@ZnO quantum dots

Facile solution-phase synthesis of remarkably luminescent and monodisperse oleate-capped ZnO nanoparticles with high colloidal stability was developed.

ZnO nanorods/Ag nanoparticles heterostructures with tunable Ag contents: A facile solution-phase synthesis and applications in photocatalysis

Needle-like ZnO nanorods (ZnO–NRs)/Ag nanoparticles (Ag–NPs) heterostructures with tunable silver contents have been successfully designed and constructed via a two-step hydrothermal approach on zinc foil. The as-fabricated heteroarchitectured composite was Ag–NPs with a size range about 30 to 50 nm in diameter assembled uniformly on the surface of needle-like ZnO–NRs, several micrometers long and about 480 nm wide near the half height of the nanorods. Through the variation of the reactant concentration such as silver nitrate, the silver content on the ZnO–NRs can be controllably tuned, which further greatly affected the photocatalytic performance of the decomposition of a representative dye pollutant of rhodamine B, and there is an optimum amount of secondary Ag–NPs. This facile method developed here also can be extended to construct other ZnO-based noble metal or semiconductor heterostructures on zinc substrates.

Fabrication of superhydrophobic surface by hierarchical growth of lotus-leaf-like boehmite on aluminum foil

Hierarchical growth of boehmite film on the aluminum foil was carried out via a facile solution-phase synthesis route. The resultant film is composed of three-dimensional microprotrusions assembled from well aligned nanoneedles. Such dual scale micro-/nanostructures are highly similar with those of lotus leaves. The resultant surface after hydrophobization exhibits a water contact angle of 169° and a sliding angle of ∼4° for a 5 μL droplet, which is ascribed to the combination of the dual scale roughness at the micro- and nanometer scale and the low surface energy of stearic acid coating. The obtained film possesses relatively good adhesion to the aluminum substrate and keeps superhydrophobicity after the ultrasonic treatment or long-term storage in spite of the partial loss of it superhydrophobic ability after abrasion test.

Formation of Hollow Upconversion Rare-Earth Fluoride Nanospheres: Nanoscale Kirkendall Effect During Ion Exchange

In this work, we report a facile solution-phase synthesis of hollow cubic phase α-NaYF4 nanoparticles by a controlled ion exchange process from cubic phase Y2O3 nanospheres. We demonstrate that hol...

Cuprous oxide nanospheres as probes for light scattering imaging analysis of live cells and for conformation identification of proteins

A facile solution-phase synthesis route of highly uniform Cu 2O nanospheres (Cu 2O NPs) with the size of 57.7 ± 4.7 nm was developed, and then the nanoparticles were applied to live cell imaging under a common dark-field microscope. Starting from copper(II) salts, the synthesis of Cu 2O NPs was made in the presence of cetyltrimethylammonium bromide (CTAB) by reducing the copper(II) with sodium borohydride (NaBH 4) in aqueous medium and by aging process in the air. Monitoring of morphology evolution process of Cu 2O NPs with scanning electron microscopy (SEM) and measuring of the UV–visible spectra showed that the synthesis of Cu 2O NPs follows the reduction–oxidation coupled process of Cu 2+ into Cu 0 species at first and then the resulted Cu 0 species into Cu 2O NPs in the air. Light scattering (LS) features have been measured with a common spectrofluorometer and a common dark-field microscope, and it was found that the as-prepared Cu 2O NPs display strong blue scattering light and can be applied for cell imaging. If incubated with human bone marrow neuroblastoma, transferrin-conjugated Cu 2O NPs can get into the cells and show strong pure blue light in cytoplasm. Further investigations showed that the Cu 2O NPs could be applied for probes for conformation of proteins.

Novel and facile solution-phase synthesis of 2,5-diketopiperazines and O-glycosylated analogs

This work describes the synthesis in solution of a series of related diketopiperazines with potential biological activities: cyclo(l-Pro-l-Ser), cyclo(l-Phe-l-Ser), cyclo(d-Phe-l-Ser) and the corresponding glycosylated analogs of the latter, cyclo[d-Phe-l-Ser(αGlcNAc)] and cyclo[d-Phe-l-Ser(βGlcNAc)]. The synthetic approach involved coupling reactions of –OH or O-glycosylated serine benzyl esters with NFmoc-protected amino acids (Pro or Phe), followed by one-pot deprotection–cyclization reaction in the presence of 20% piperidine in DMF.

Solution-phase synthesis of inorganic hollow structures by templating strategies

The solution-phase synthesis of hollow micro- and nanostructures by using suitable templates such as hard templates, soft templates and reactive templates has attracted considerable attention in recent years. This paper is focused on the template synthesis of inorganic hollow structures with tailored size, morphology, and architecture, with emphasis on the templating strategies recently developed in our lab for the facile solution-phase synthesis of novel inorganic hollow structures. The formation mechanisms of the hollow structures via different kinds of templates are discussed in depth to show the general concepts for the preparation processes. The properties and applications of hollow structures are briefly described, demonstrating the promising and broad application fields of hollow materials.