Diels–Alder “click” reactions: recent applications in polymer and material science

Methods, Morphologies, and Applications Shuai Chen,†,‡ Paul Slattum, Chuanyi Wang,*,† and Ling Zang* †Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011, China ‡The Graduate School of Chinese Academy of Science, Beijing 100049, China Nano Institute of Utah and Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, United States Vaporsens Inc., Salt Lake City, Utah 84112, United States

Self-Assembly of Perylene Imide Molecules into 1D Nanostructures: Methods, Morphologies, and Applications

Modifications of carbon for polymer composites and nanocomposites

Ozonation and UV254 nm radiation for the removal of microorganisms and antibiotic resistance genes from urban wastewater

An overview of graphene materials: Properties, applications and toxicity on aquatic environments.

Humic acids (HAs) content of raw water is an important analytical parameter in water treatment facilities because HAs in the presence of chlorine may lead to the formation of dangerous by-products (e.g., trihalomethanes). The concentration of HAs in water is not directly accessible by common analytical methods due to their heterogeneous chemical structure. The aim of this study was to compare two methods to assess humic acids (HAs) in surface water namely absorbance of ultraviolet light at 254 nm (UV254) and total organic carbon (TOC), as well as to evaluate the effects of calcium and magnesium concentrations, pH and sample filtration on the methods' results. An aqueous solution of a commercial HA with 10 mg L−1 was used in the present work. Quantification of the HA was carried out by both UV254 and TOC (combustion-infrared method) measurements. UV254 results were converted to TOC using a calibration curve. The effects of calcium (0–136.3 mg L−1) and magnesium (0–34.5 mg L−1) concentrations, pH (4.0, 7.0 and 9.0) and sample filtration on UV254 and TOC measurements of the HA suspension were evaluated. More accurate TOC values of HA suspensions were obtained by the combustion-infrared method than by the UV254 absorbance method. The higher differences of TOC values between unfiltered and filtered samples were detected in the presence of calcium at pH 9.0 using the spectrophotometric method.

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Quantification of humic acids in surface water: effects of divalent cations, pH, and filtration.

Functionalization of carbon nanofibres by 1,3-dipolar cycloaddition reactions and its effect on composite properties

We report a straightforward heat treatment in air of commercial screen-printed carbon electrodes (SPCE) at different temperatures and times (ht-SPCE) that produces considerable electrocatalytic effects. The active area and the presence of oxygen groups on the ht-SPCE surface increased upon thermal treatment, more than doubling and by 20%, respectively. The increase of oxygen-containing carbon surface groups results in strong interactions and substantial improvement in Faradaic currents, up to a 10 fold increase in the voltammetric response of relevant polyphenols (hydroquinone, catechol, pyrogallol and dopamine). Moreover, ht-SPCE displayed higher selectivity towards the oxidation of polyphenol mixtures than the untreated SPCE. Finally, good linear ranges were obtained by voltammetric determination of dopamine with detection and quantification limits 5 times lower than the values obtained for the untreated SPCE. The versatility of oxidation by air makes this activation procedure very attractive and easy to implement, which can be further used for numerous applications in the (bio)sensor field.

Enhanced electrochemical sensing of polyphenols by an oxygen-mediated surface

A selection of bolaamphiphilic perylene bisimides (PBI) were prepared from the reaction of perylenetetracarboxylic dianhydride with α-amino acids. These molecules were obtained in good yield using a simple synthetic protocol and avoiding the need for complex purification methods, a major advantage for future applications. Carbon nanotubes (CNT) were dispersed in an aqueous solution of the PBI, buffered at pH 7, and the suspension was studied by absorption and emission spectroscopy. PBI functionalized with Boc-lysine and phenylalanine led to an excellent suspension of CNT in water, stable for at least 24 h at room temperature. Theoretical calculations were used to support and explain the experimental observations.

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Efficient dispersion of multi-walled carbon nanotubes in aqueous solution by non-covalent interaction with perylene bisimides

Carbon nanofibers were functionalized using a reaction scheme described in the literature for 1,3-dipolar cycloaddition of azomethine ylides generated in situ by the condensation of an alpha-amino acid and an aldehyde The reagents used were Z-Gly-OH and paraformaldehyde Their reaction with carbon nanofibers was studied as a solid mixture by controlled heating in the DSC An oxazolidinone intermediate was formed as the major product Z-Gly-OH and paraformaldehyde were also reacted with a model compound (anthracene) in DMF solution leading to the formation of a considerable amount of anthraquinone These studies suggested that, under the conditions investigated, the 1,3-dipolar cycloaddition reaction was not favoured, and the main result of functionalization was the formation of quinone-type groups as a consequence of an oxidation process

Maria Fernanda Proença

Papers

Quantification of humic acids in surface water: effects of divalent cations, pH, and filtration.

Functionalization of carbon nanofibres by 1,3-dipolar cycloaddition reactions and its effect on composite properties

Enhanced electrochemical sensing of polyphenols by an oxygen-mediated surface

Efficient dispersion of multi-walled carbon nanotubes in aqueous solution by non-covalent interaction with perylene bisimides

The 1,3-dipolar cycloaddition reaction in the functionalization of carbon nanofibers.