Introduction Of Functional Groups Research Articles

New asymmetric synthesis of a pheromone component of the shield bug Cantao Parentum

A novel procedure has been developed for the synthesis of (2S,4R,6R,8S)-2,4,8-trimethyl-1,7-dioxaspiro[5.5]undecane, a pheromone component of the shield bug Cantao Parentum, through intermediate cyclopropanol derivatives in the key stages of carbon chain construction and introduction of functional groups.

Immobilization of carbon nanotubes on functionalized graphene film grown by chemical vapor deposition and characterization of the hybrid material

We report the surface functionalization of graphene films grown by chemical vapor deposition and fabrication of a hybrid material combining multi-walled carbon nanotubes and graphene (CNT–G). Amine-terminated self-assembled monolayers were prepared on graphene by the UV-modification of oxidized groups introduced onto the film surface. Amine-termination led to effective interaction with functionalized CNTs to assemble a CNT–G hybrid through covalent bonding. Characterization clearly showed no defects of the graphene film after the immobilization reaction with CNT. In addition, the hybrid graphene material revealed a distinctive CNT–G structure and p–n type electrical properties. The introduction of functional groups on the graphene film surface and fabrication of CNT–G hybrids with the present technique could provide an efficient, novel route to device fabrication.

Synthesis of Tetrahydrohonokiol Derivates and Their Evaluation for Cytotoxic Activity against CCRF-CEM Leukemia, U251 Glioblastoma and HCT-116 Colon Cancer Cells

Biphenyl neolignans such as honokiol and magnolol, which are the major active constituents of the Asian medicinal plant Magnolia officinalis, are known to exert a multitude of pharmacological and biological activities. Among these, cytotoxic and tumor growth inhibitory activity against various tumour cell lines are well-documented. To further elucidate the cytotoxic effects of honokiol derivatives, derivatizations were performed using tetrahydrohonokiol as a scaffold. The derivatizations comprised the introduction of functional groups, e.g., nitro and amino groups, as well as alkylation. This way, 18 derivatives, of which 13 were previously undescribed compounds, were evaluated against CCRF-CEM leukemia cells, U251 glioblastoma and HCT-116 colon cancer cells. The results revealed no significant cytotoxic effects in any of the three tested cell lines at a test concentration of 10 µM.

Swift modification of resistively heated carbon nanotube films by the action of hydrogen peroxide

We have developed a benign technique for the modification of electrical and structural properties of horizontally aligned carbon nanotube (CNT) films. The as-made CNT films were immersed in 30%wt aqueous solution of hydrogen peroxide whilst current was passed through the nanotube bundles to bring the temperature of CNTs up to 200°C. Depending on the employed conditions, we either successfully removed extraneous material contaminating CNT films and decreased its resistance by 40% or initiated the introduction of functional groups. The whole process lasted only for 1min and was more straightforward, less expensive and more ecologically friendly than the current post-processing technologies. We imagine that such a method of tweaking up electrical and/or structural properties could be successfully employed to a range of nanomaterials with a particular focus on carbon C-sp2 nanostructures.

Novel method of electrical resistance measurement in structural composite materials for interfacial and dispersion evaluation with nano- and hetero-structures

ABSTRACTInterest in development in the use of nanoparticles in structural composites for the improvement of thermal conductivity, mechanical properties and electrical properties has recently stimulated some research efforts. Such improvements require the introduction of functional groups and the proper selection and concentration of the nanoparticles, as well as their uniform dispersion. The identification and verification of uniformity of dispersion is very important in the efficient processing for improved performance. Recently, new methods for studying and evaluating the interfacial properties between the reinforcing fibers and the epoxy matrix, have been developed. Distinct from FE-SEM observation, electrical resistance methods are being developed which can be applied for to measure interfacial shear strength (IFSS) and degree of dispersion. The main principle, on which the electrical resistance measurement is based, is Kirchhoff’s laws, which considers conductive materials as electrical circuits. In this research, the self sensing character of the conductive carbon nanotubes (CNT) and conventional carbon reinforcing fibers has been successfully used as a method for evaluating the dispersion of nanoparticles and interfacial adhesion. The electrical resistance in these composites was observed to be dependent on differences in wetting and interfacial adhesion between matrix and fillers. In summary, a correlation was observed between the electrical resistance and dispersion and degree of cure. It is felt that these methods, along with the electro-micromechanical methods, provide valuable tools for investigating the role of interfacial behavior on thermal conductivity, electrical and mechanical properties. Optical observations by FE-SEM of degree of dispersion and interfacial adhesion are consistent with the electrical resistance results. Additionally, it may be possible to use electrical resistance circuit analysis to detect the location of and extent of micro-damage within composite materials.

Stability and catalytic properties of porous acidic (organo)silica materials for conversion of carbohydrates

Sulfonic acid-modified mesoporous SBA-15-type silica and hybrid organosilica catalysts were prepared using the co-condensation and grafting functionalization methods. The catalytic activity of these materials for fructose dehydration to 5-hydroxymethylfurfural was studied in aqueous medium and in DMSO. The prepared materials were characterized by XRD, SEM, elemental analysis, nitrogen physisorption and 29Si CP MAS NMR. Special focus was on evaluating the influence of the structural modification of the mesoporous catalysts on their stability under the conditions of catalytic conversion of carbohydrates. In aqueous medium all catalysts show very low activity and HMF selectivity. However, when the reaction is carried out in DMSO, HMF yields of up to 88% can be achieved with a minimum amount of sulfonic acid-modified catalyst. Among the materials tested, the hybrid organosilica-based catalyst shows the highest dehydration rate. It is demonstrated that pure silica-based catalysts degrade strongly under the catalytic conditions. The hydrothermal stability of the mesoporous catalysts is improved in the presence of organic moieties in their structure. The co-condensed organic–inorganic catalysts retain much better the mesoporosity and are less susceptible to the loss of catalytic functional groups anchored to their surface compared to their pure silica counterparts. The methodology for the introduction of functional groups has also a profound impact on the catalyst stability. Species incorporated into the catalysts via the direct co-condensation method show much higher stability than those introduced via a post-synthetic grafting procedure.

Small change, big red shift: syntheses, structure and photoluminescence of Cu2Br2(Ph3P)2py2 (py=pyridine, 4-vinylpyridine)

Abstract The search for efficient, luminescent metal complexes for optoelectronic devices raised the interest for emissive Cu(I) compounds. Cu(I)-complexes of the type [Cu2X2(PR3)2(py)2] (py = pyridine derivative, X = Cl, Br, I) usually are efficient, blue-emitting compounds that can potentially be used as new emitter materials in organic light-emitting diodes. Aside from photophysical requirements, the introduction of functional groups is often necessary to enable processing and stabilization, e.g. by cross-linking or polymerization. Using 4-vinylpyridine instead of pyridine to enable crosslinking during device fabrication, a structurally similar complex with different photophysical properties is obtained: a bathochromic shift of over 100 nm occurs, while the photoluminescence quantum efficiency is drastically decreased. DFT-calculations, X-ray-diffraction and photoluminescence spectroscopy were used to compare Cu2Br2(Ph3P)2(pyridine)2 and Cu2Br2(Ph3P)2(4-vinylpyridine)2. The structural differences regarding the core unit, Cu2Br2P2N2, are only small, but the π-system of the pyridine ligand is enlarged by the vinyl group leading to a significant red-shift of the emission wavelength.

ChemInform Abstract: Whole‐Cell Biocatalysis for Selective and Productive C—O Functional Group Introduction and Modification

AbstractReview: 331 refs.

Improved Efficiency of Ethylene/Ethane Separation Using a Symmetrical Dual Nitrile-Functionalized Ionic Liquid

As green and designable solvents, ionic liquids (ILs), have great potential in the separation of olefins and paraffins. The introduction of functional groups into ILs enhances its separation selectivity for olefin to paraffin; however, the absorption capacities of such functionalized ILs obviously decrease due to the strong polarity of the functional group. In this work, we designed a symmetrical dual nitrile-functionalized IL 1,3-dibutyronitrile-imidazolium bis((trifluoromethyl)sulfonyl)imide ([(CP)2im][NTf2]) and determined the solubility of ethylene and ethane at 303.15 K in three ILs: nonfunctionalized 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmim][NTf2]), single-functionalized 1-butyronitrile-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide ([CPmim][NTf2]), and dual-functionalized [(CP)2im][NTf2]. The experimental results showed that enhanced separation selectivity for ethylene/ethane could be achieved in the symmetrical dual-functionalized [(CP)2im][NTf2] with only a slight reduction of absorption capacity. A COSMO-RS calculation was carried out to understand the underlying dissolution mechanism of ethylene and ethane in ILs and showed that the polarity of the IL and its misfit interaction with gases were the major factors in determining the solubilities of ethylene and ethane in it. In addition, a silver-containing IL was also tested because of its higher absorption capacity for olefins. It was found that the silver-containing IL was superior to any of the common ILs in the separation of ethylene/ethane, particularly [Bmim][NTf2]. A simple equilibrium model was used to describe the absorption of ethylene in the silver-containing IL.

Energy Transfer at the Single‐Molecule Level: Synthesis of a Donor–Acceptor Dyad from Perylene and Terrylene Diimides

In 2004, we reported single-pair fluorescence resonance energy transfer (spFRET), based on a perylene diimide (PDI) and terrylene diimide (TDI) dyad (1) that was bridged by a rigid substituted para-terphenyl spacer. Since then, several further single-molecule-level investigations on this specific compound have been performed. Herein, we focus on the synthesis of this dyad and the different approaches that can be employed. An optimized reaction pathway was chosen, considering the solubilities, reactivities, and accessibilities of the building blocks for each individual reaction whilst still using established synthetic techniques, including imidization, Suzuki coupling, and cyclization reactions. The key differentiating consideration in this approach to the synthesis of dyad 1 is the introduction of functional groups in a nonsymmetrical manner onto either the perylene diimide or the terrylene diimide by using imidization reactions. Combined with well-defined purification conditions, this modified approach allows dyad 1 to be obtained in reasonable quantities in good yield.

Blood compatibility of polyethersulfone membrane by blending a sulfated derivative of chitosan

In this study, a novel sulfated derivative of chitosan, which could be dissolved in many common organic solvents, is conveniently synthesized for the modification of polyethersulfone (PES) membrane. Elemental analysis, FTIR, 1H NMR and X-ray diffraction diagrams (XRD) are used to demonstrate the introduction of functional groups. Owing to the solubility in organic solvents, the sulfated derivative of chitosan could be directly blended with PES in organic solvent to prepare membrane by means of a liquid–liquid phase separation technique. The modified membrane showed lower protein (bovine serum albumin (BSA) and bovine serum fibrinogen (BFG)) adsorption and suppressed platelet adhesion. Moreover, the activated partial thromboplastin time (APTT) for the modified membrane was enhanced as high as 60% compared to pure PES membrane. The lower protein adsorption, suppressed platelet adhesion and increased APTT confirmed that the blood compatibility of the modified PES membrane by the sulfated derivative of chitosan was significantly improved.

Surface etching of methacrylic microparticles via basic hydrolysis and introduction of functional groups for click chemistry

Controlled basic hydrolysis of poly(methyl methacrylate-co-ethylene glycol dimethacrylate) P(MMA-co-EGDMA) microparticles with a diameter d50=6μm led to high densities of carboxylic groups at the particles’ surface of up to 1.288μeqg−1 (equivalent to 1.277μmolm−2). The microparticles’ core has not been altered by this surface activation procedure as seen by fluorescent staining. The kinetics of the hydrolysis reaction was investigated via electrophoretic light scattering and particle charge detection employing polycation titration under shear condition. The activated microparticle’s surface was subsequently exploited in carbodiimide-mediated coupling reactions using a variety of molecular reactants, that is, 11-azido-3,6,9-trioxaundecan-1-amine, cysteamine, propargylamine, and fluoresceinamine, thus enabling the introduction of chemically reactive moieties such as azides, thiols, and alkynes. Fluorescent staining of the particles’ surface successfully demonstrated the versatile applications of surface functionalized microparticles via copper-catalyzed huisgen cycloaddition. Carrying on this two-step procedure in a controlled manner provides an excellent way for relatively simple but highly effective surface functionalization.

A rapid method for the assessment of the surface group density of carboxylic acid-functionalized polystyrene microparticles

Particle-based assays are becoming versatile analytical tools due to their cost-effectiveness, speed, straightforward and diverse functionalization chemistries, especially when polystyrene particles are used. The introduction of functional groups (-COOH, -NH2, etc.) to the surface of such polystyrene particles promotes their application in bioanalytics. However, the traditional method to determine the amount of surface carboxylate groups is conductivity titration, which is usually time- and resources-consuming and discontinuous. Here, we synthesized polystyrene microparticles with different contents of carboxylate groups, and then investigated a simpler and potentially continuous approach to determine the amount of surface carboxylate groups by Zeta potential measurements. The results were compared to the traditional titration method and to actual coupling efficiencies of the functionalized particles with a model oligonucleotide probe as determined by flow cytometry. All quantification methods revealed good agreement.

Hybrids of Graphenes and Silver Nanoparticles Prepared by <i>In Situ</i> Process Employing Microwaveirradiation

Fine dispersion of graphenes is crucial for the application of graphenein various fields. However, graphenes are frequently aggregated due to the large surface area and van der Waals interactions between themselves during the mixing process. Thus, various modifications of graphenes are necessary for the fine dispersion. Introduction of functional groups into graphenes accompanies loss of inherent advantages. In this study, introduction of silver nanoparticles into graphenes by in situ process was investigated. Especially, microwave irradiation was employed for the syntheses sincegraphenes absorb microwave efficiently and became heated quickly. Formation of silver nanoparticles on the grapheneafter microwave irradiation was confirmed and the average diameter of the silver nanoparticles in the hybrids was about 30 nm. Rheological and electrical properties of the epoxy resins filled with the hybrids are discussed in this report.

Whole-cell biocatalysis for selective and productive C–O functional group introduction and modification

During the last decades, biocatalysis became of increasing importance for chemical and pharmaceutical industries. Regarding regio- and stereospecificity, enzymes have shown to be superior compared to traditional chemical synthesis approaches, especially in C-O functional group chemistry. Catalysts established on a process level are diverse and can be classified along a functional continuum starting with single-step biotransformations using isolated enzymes or microbial strains towards fermentative processes with recombinant microorganisms containing artificial synthetic pathways. The complex organization of respective enzymes combined with aspects such as cofactor dependency and low stability in isolated form often favors the use of whole cells over that of isolated enzymes. Based on an inventory of the large spectrum of biocatalytic C-O functional group chemistry, this review focuses on highlighting the potentials, limitations, and solutions offered by the application of self-regenerating microbial cells as biocatalysts. Different cellular functionalities are discussed in the light of their (possible) contribution to catalyst efficiency. The combined achievements in the areas of protein, genetic, metabolic, and reaction engineering enable the development of whole-cell biocatalysts as powerful tools in organic synthesis.

Anion receptors based on ureidocalix[4]arenes immobilised in the partial cone conformation

A novel method enabling the synthesis of receptors based on the calix[4]arenes immobilized in the partial cone conformation is reported. The application of a protection/deprotection strategy using nosyl groups enables the regioselective introduction of functional groups (NO2 and NH2) into the upper rim of calix[4]arenes, leading finally to the substitution pattern so far inaccessible to calixarene chemistry. The introduction of two ureido functions at the para positions of the partial cone conformer yields a novel type of receptor which can bind anions even in a highly competitive solvent (DMSO). This revealed that the partial cone conformation, so far rather ignored in supramolecular chemistry, can be also very useful in design of novel anion receptors.

Contact angle hysteresis on plasma treated polyethylene terephthalate

AbstractKnowledge of contact angle hysteresis is important to the understanding of surface wettability and to controlling further surface wetting behaviour. The wettability can be affected by surface modification. This study is a look on surfaces modified by the usage of plasma. We describe the effect of plasma treatments on contact angle hysteresis by the use of Diffuse Coplanar Surface Dielectric Barrier Discharge (DCSBD). Modification of the surface was achieved using textile made from polyethylene terephthalate (PET). Results have shown that both advancing and receding contact angle were significantly reduced by the process. The contact angle hysteresis was decreased after the plasma treatment as was observed by measurement taken at various time intervals and this fact correspond with introduction of functional groups detected by X - ray photoelectron spectroscopy (XPS).

Radiation-induced grafting of acrylic acid onto expanded poly(tetrafluoroethylene) membranes

Expanded poly(tetrafluoroethylene) (ePTFE) is currently being applied in facial reconstruction surgery. One requirement for the use of ePTFE membranes in soft tissue replacements is establishment of a well-bonded interface with the surrounding bone. However, ePTFE is classified as bioinert, thus lacking in biomimetic properties which may result in poor osseointegration at the bone–implant interface. Thus, the introduction of functional groups onto the polymer surface was carried out in the current study using radiation induced grafting of acrylic acid (AA) yielding graft yields of up to 40%. This resulted in reducing the hydrophobicity (advancing contact angle reduced from 116 to 92°). XPS revealed that the grafted PAA was highly crosslinked. The effects of grafting conditions (dose, monomer concentration, as well as solvent) on the grafting outcome were evaluated. Grafting of tertbutyl acrylate (tBA) was investigated but low graft yields were obtained and this was shown to be unaffected by the solvent used during the grafting process. The mechanical properties of the AA grafted membranes were altered significantly and were dependent on the testing conditions (wet or dry).

Targeting the Hinge Glycine Flip and the Activation Loop: Novel Approach to Potent p38α Inhibitors

The p38 MAP kinase is a key player in signaling pathways regulating the biosynthesis of inflammatory cytokines. Small molecule p38 inhibitors suppress the production of these cytokines. Therefore p38 is a promising drug target for novel anti-inflammatory drugs. In this study, we report novel dibenzepinones, dibenzoxepines, and benzosuberones as p38α MAP kinase inhibitors. Previously reported dibenzepinones and dibenzoxepines were chemically modified by introduction of functional groups or removal of a phenyl ring. This should result in targeting of the hydrophobic region I, the "deep pocket", and the hinge glycine flip of the kinase. Potent inhibitors with IC(50) values in the single digit nanomolar range (up to 3 nM) were identified. Instead of targeting the "deep pocket" in the DFG-out conformation, interactions with the DFG-motif in the in-conformation could be observed by protein X-ray crystallography.

New polyaniline/polypyrrole/polythiophene and functionalized multiwalled carbon nanotube-based nanocomposites

In this endeavor, a new type of nanocomposites has been developed from conducting organic polymers (layer-by-layer in situ polymerization of various monomers) and functionalized multiwalled carbon nanotubes (MWCNTs). Initially, functionalization of MWCNTs was achieved by sulfuric acid (H2SO4):nitric acid (HNO3) and HNO3:hydrogen peroxide treatment. A comparative study regarding the synthetic, morphological, and electrical profiles of raw MWCNTs (R-MWCNTs), pure-MWCNTs (P-MWCNTs), functionalized MWCNTs (F-MWCNTs), and polyaniline/polypyrrole/polythiophene-F-MWCNTs (PANI/PPy/PTh/F-MWCNTs) nanocomposites was successfully carried out. Introduction of functional groups on the surface of MWCNTs was confirmed by Fourier transform infrared spectra. Energy dispersive x-ray spectroscopy and Rutherford back scattering were employed for the elemental analyses. Morphology of the obtained hybrid material was studied via scanning electron microscopy and their thermal stability was investigated using thermogravimetric analysis. The dielectric constant and electrical conductivity were also measured. Result exploration revealed that F-MWCNTs were well functionalized ensuing interfacial entrapment between the carbon nanotubes and the matrix. In addition, the layer-by-layer deposition of PPy/PANI/PTh polymers enhanced the electrical conductivity of material relative to the neat ones. Besides, the improved thermal stability of composite was acquired when compared with the homopolymers.