Difluoromethylenediphosphonate: a convenient, scalable, and high-yielding synthesis

[reaction: see text] Since the first disclosure of difluoromethylenediphosphonate, 2, almost 40 years ago, interest in this compound has flourished in several research areas. In this paper, we present a convenient, high-yielding (99% overall) method for the preparation of milligram to multigram quantities of 2 (as the bis(tributylammonium salt, 2b) in a solid form that is easy to handle.     

Trans-, cis-, and dihydro-resveratrol: a comparative study

Because of the shifted focus in life science research from genome analyses to genetic and protein function analyses, we now know functions of numerous proteins. These analyses, including those of newly identified proteins, are expected to contribute to the identification of proteins of therapeutic value in various diseases. Consequently, pharmacoproteomic-based drug discovery and development of protein therapies attracted a great deal of attention in recent years. Clinical applications of most of these proteins are, however, limited because of their unexpectedly low therapeutic effects, resulting from the proteolytic degradation in vivo followed by rapid removal from the circulatory system. Therefore, frequent administration of excessively high dose of a protein is required to observe its therapeutic effect in vivo. This often results in impaired homeostasis in vivo and leads to severe adverse effects. To overcome these problems, we have devised a method for chemical modification of proteins with polyethylene glycol (PEGylation) and other water-soluble polymers. In addition, we have established a method for creating functional mutant proteins (muteins) with desired properties, and developed a site-specific polymer-conjugation method to further improve their therapeutic potency. In this review, we are introducing our original protein-drug innovation system mentioned above.     

Chemical substance,material, product,goods, waste: a changing ontology

A chemical substance (CS) is instantiated in the material world by a number of quantities of such substance (QCSs), placed in different locations. A change of location implies a change in the net of relationships entertained by the QCS with the region wherein it is found. This fact entails changes of the ontological status of the CS, as this is not fully determined by the inherent features of the CS and includes a relevant relational contribution. In order to demonstrate this thesis, we have chosen to analyse the status of quantities of a same CS that are synchronically located in different spacetime regions: a synthetic lab, a lab where the QCS is turned into a material, an industrial plant, the market where the QCS gets a price and a dump waste where the QCS is discarded, respectively:

Chemical substance Open image in new window material Open image in new window (industrial) product Open image in new window goods Open image in new window waste

The use of first-order predicate logic, mereology and locative logic allows carrying out a regimentation process that highlights the ontological commitments implied by the formal expressions through which each element of the aforementioned series can be described. The presence of relational properties discloses the systemic nature of the CS instantiated within a spacetime region. The implications of such an aspect are discussed.

     

Droplet on a liquid substrate: Wetting,dewetting, dynamics,instabilities

Droplets on a liquid substrate (‘liquid lenses’) play an important role in various branches of engineering, including microfluidics, chemical engineering, environment protection, etc. In the present paper, we discuss basic phenomena characteristic for liquid lenses. We recall classical results on the shape of an equilibrium droplet and the kinds of droplet wetting. We overview briefly the main theoretical approaches used for the analysis of droplet dynamics, discuss the phenomena accompanying a droplet impact, physical effects used for droplet manipulations, and the factors that determine the interaction between droplets. We describe the main types of droplet instabilities leading to oscillations, self-propulsion, and disintegration of droplets. Some promising directions of further research are listed.     

Zr-TUD-1: a Lewis acidic, three-dimensional, mesoporous, zirconium-containing catalyst

A three-dimensional, mesoporous, silicate containing zirconium, Zr-TUD-1, was synthesized by a direct hydrothermal treatment method with triethanolamine as a complexing and templating reagent to ensure that zirconium was incorporated as isolated atoms. The mesoporosity of Zr-TUD-1 was confirmed by X-ray diffraction (XRD), N(2) sorption and high-resolution transmission electron micrograph (HR-TEM) studies. The nature and strength of the Lewis acid sites present in Zr-TUD-1 were evaluated by FTIR studies of pyridine adsorption and temperature-programmed desorption of ammonia. FTIR, X-ray photoelectron spectroscopic (XPS) and UV/Vis spectroscopic studies showed that, at Si/Zr ratios of 25 and higher, all the zirconium was tetrahedrally incorporated into the mesoporous framework, while at low Si/Zr ratios, a small part of the zirconium was present as ZrO(2) nanoparticles. Zr-TUD-1 is a Lewis acidic, stable and recyclable catalyst for the Meerwein-Ponndorf-Verley (MPV) reaction and for the Prins reaction.     

N,N-dimethylformamide: a multipurpose building block

Often used as a common solvent for chemical reations and utilized widely in industry as a reagent, N,N-dimethylformamide (DMF) has played an important role in organic synthesis for a long time. Numerous highly useful articles and reviews discussing its utilizations have been published. With a focus on the performance of DMF as a multipurpose precursor for various units in numerous reactions, this Minireview summarizes recent developments in the employment of DMF in the fields of formylation, aminocarbonylation, amination, amidation, and cyanation, as well as its reaction with arynes.     

Introduction: María Victoria Roux, colleague, calorimetrist, and friend

This essay is the introductory paper for a special issue of Structural Chemistry explicitly dedicated to the premier Spanish calorimetrist and thermochemist, our colleague and friend, María Victoria Roux. The studies in this issue were written on the occasion of her recent retirement from the CSIC Institute of Physical Chemistry “Rocasolano,” Madrid.     

Wenliang Wang a,Wenli Zhao a,Haochun Zhang a,Xincheng Dou a,Haifeng Shi a,b,

近年来, Fenton反应由于其成本低,反应速度快,操作简单等优势受到了广泛的研究.传统的均相Fenton反应可通过H2O2氧化Fe2+产生具有强氧化性的羟基自由基,用于处理难降解的有机物.然而, Fenton反应存在两个主要问题,首先,在Fenton反应中需要加入大量的酸来维持酸性环境,以保证反应的最佳活性.其次, Fenton反应中铁离子不断流失并形成固体污泥,这严重影响了Fenton反应产生·OH的效率.目前,将光催化反应与非均相芬顿反应相结合是改善这些问题的有效方案.非均相光芬顿反应不仅能提高有机物降解的活性,而且通过光催化剂导带上的电子有效减少Fe3+的浸出和铁氢氧化物沉淀的产生.最近,作为一种可见光Fenton催化剂,α-Fe2O3可以在几乎中性的条件下发生光芬顿反应,这解决了在反应过程中需要随时调整PH值的问题.此外,光照条件下α-Fe2O3价带上的电子能跃迁至导带并将Fe3+还原成Fe2+,从而减少铁离子的损耗.然而,由于光生载流子复合率较高等问题,单一α-Fe2O3光催化剂的催化活性仍不理想.构建具有2D/2D结构的S型异质结可以缩短电子在界面间的传输距离,增大材料的活性位点,将光生电子-空穴在空间上分离,从而有效增强光生载流子的分离效率.因此,构建2D/2Dα-Fe2O3/Bi2WO6 S型异质结,并用于光芬顿反应有望进一步提高对有机污染物的降解效率.本文通过简易的水热法制备了具有2D/2D结构的α-Fe2O3/Bi2WO6 S型异质结光芬顿催化剂,并通过XRD、BET、TEM、XPS和UV-Vis等手段对催化剂的晶体结构、元素状态、微观结构、光学性质和化学组分进行了表征.通过在可见光照射下降解甲基蓝(MB),考察了α-Fe2O3/Bi2WO6的光芬顿催化活性.结果表明,由于光催化反应与Fenton反应的协同作用,α-Fe2O3/Bi2WO6表现出了明显增强的光-Fenton催化活性,最佳比例的α-Fe2O3/Bi2WO6的活性分别是单一α-Fe2O3和Bi2WO6的11.06倍和3.29倍.本文将光催化反应与Fenton反应相结合,一方面,光催化反应对Fe3+的还原有促进作用,提高了Fe2+的浓度,从而提升羟基自由基的产量;另一方面, Fenton反应对α-Fe2O3/Bi2WO6中电子的利用阻止了光生载流子的复合,进一步提高了光催化降解效率.此外,由于二维纳米片之间具有更大的接触面积, 2D/2D异质结可以缩短电荷传输时间和距离,促进了光生电子-空穴的分离.同时,具有较大比表面积的2D/2D材料可以在催化剂表面提供大量用于有机物氧化分解的活性位点.而S型异质结的构建不但促进了界面电荷的转移和分离,还能维持最佳的电荷氧化还原电位,这都提升了催化剂的光芬顿催化活性.总之,本文为合成可高效降解有机污染物的非均相光-芬顿催化剂提供了新的思路.     

Urea-, squaramide-, and sulfonamide-based anion receptors: a thermodynamic study

In this work, we compare the anion-binding capabilities of receptors 1-5, characterized by similar structures, but possessing different hydrogen-bond-donor moieties (urea, squaramide, and sulfonamide). The presence of chromophoric substituents on the receptor's skeleton allowed the determination of association constants by performing UV/Vis titrations with the investigated anions on solutions of the receptors in pure acetonitrile. Additional quantitative studies of the anion-binding properties of receptors 1-5 were performed by isothermal titration calorimetry (ITC). The experimental results indicated that 1 and 2 formed 1:1 hydrogen-bonded complexes with most of the anions investigated. In the case of receptors 3-5, the formation of the 1:1 adduct was observed only with anions of low basicity (i.e., chloride, bromide, iodide, and hydrogen sulfate). With more basic anions (i.e., acetate and dihydrogen phosphate), both spectrophotometric and ITC titrations accounted for the deprotonation of the sulfonamide group, involving the formation of the conjugated base of the receptor.     

Combination of electrophoresis,chromatography, and magnetism in a single separation technique: Part 1: a first theoretical evaluation

Magnetic nanoparticles incorporated into the layer of a (polymeric) sorbent, covering the inner surface of a fused silica capillary, can produce—upon applying an electric field across the capillary length—an electromagnetic field that would affect to some extent the separation of charged analytes. A first theoretical assessment of such phenomenon is given here with a view of developing a novel hybrid separation technique based on the principles of electrophoresis, chromatography, and magnetism. Specifically, the effect of built-in magnetic nanoparticles, varying in absolute number, on the strength of axial electric field in an open-tubular column for capillary electrochromatography (CEC) column for CEC—being expressed through the associated changes in near-wall dielectric constant—was analyzed using linearized Poisson–Boltzmann equation.     

Fluorous dimethyl sulfide: a convenient,odorless, recyclable borane carrier

Borane gas and 2-(perfluorooctyl)ethyl methyl sulfide form a solid comprised of an approximately 1:1 mixture (fluorous BMS) of sulfide and the corresponding sulfide-borane. Fluorous BMS permits hydroboration of alkenes in a dichloromethane/perfluorinated hydrocarbon mixture with subsequent recycling of the fluorous sulfide by fluorous extraction. The use of fluorous BMS in the asymmetric reduction of ketones catalyzed by a chiral oxaborolidine catalyst, and in the reduction of other functional groups, is also reported. [reaction: see text]     

SERS as a bioassay platform: fundamentals, design, and applications

Bioanalytical science is experiencing a period of unprecedented growth. Drivers behind this growth include the need to detect markers central to human and veterinary diagnostics at ever-lower levels and greater speeds. A set of parallel arguments applies to pathogens with respect to bioterrorism prevention and food and water safety. This tutorial review outlines our recent explorations on the use of surface enhanced Raman scattering (SERS) for detection of proteins, viruses, and microorganisms in heterogeneous immunoassays. It will detail the design and fabrication of the assay platform, including the capture substrate and nanoparticle-based labels. The latter, which is the cornerstone of our strategy, relies on the construction of gold nanoparticles modified with both an intrinsically strong Raman scatterer and an antibody. This labelling motif, referred to as extrinsic Raman labels (ERLs), takes advantage of the well-established signal enhancement of scatterers when coated on nanometre-sized gold particles, whereas the antibody imparts antigenic specificity. We will also examine the role of plasmon coupling between the ERLs and capture substrate, and challenges related to particle stability, nonspecific adsorption, and assay speed.     

Phenyltrisalanine: a new,C3-symmetric,trifunctional amino acid

Two derivatives of phenyltrisalanine, a new, trifunctional amino acid, were synthesised in optically active forms. Two complementary techniques were employed, an HWE olefination reaction or a Heck coupling reaction, and the resulting dehydroamino acids were hydrogenated using a chiral Rh(I)–Et-DuPHOS catalyst. Phenyltrisalanine derivatives of excellent stereoisomeric purities were thus obtained.