Band 88, Heft 1-2

Sulfur and nitrogen (half-)mustard carbonate analogues are a new class of compounds, easily synthesized by methoxycarbonylation reaction of the parent alcohols with dialkyl carbonates. In this work, their reactivity as novel, green electrophiles is reported. Reactions have been conducted in autoclave conditions at high temperature (180°C), under pressure and in absence of any base, as well as, in neat at atmospheric pressure, lower temperature (150°C) and in the presence of a catalytic amount of a base. Several nucleophiles have been investigated resulting, in some cases, in unexpected compounds, i.e., six-membered heterocycle piperidine. Reaction mechanism and kinetics have been studied confirming that these compounds retain the anchimeric effect of their mustard gas analogues, without being toxic. Noteworthy, a symmetrical nitrogen mustard carbonate has also been employed as reagent in the preparation of a new family of macrocycles i.e., azacrowns, before not easily accessible.

The amount of waste generated in cashew nut processing factories has caused serious problems for a long time. However, this situation is about to change because they are being turned into an opportunity by a variety of bio-based chemicals. Todate, cashew nut shells (CNS) have proven to be among the most versatile renewable resource as they produce cashew nut shell liquid (CNSL). CNSL which is a dark reddish brown viscous liquid ( ca . 30–35 wt%) is extracted from the soft honeycomb of the CNS. The shells have been regarded as a by-product of the cashew industry though now it is a cheaper source of natural unsaturated phenols. CNSL offers a multitude of interesting possibilities for the synthesis of speciality chemicals, high value products and polymers. Our recent research efforts have demonstrated that its constituents can be transformed into diverse functional chemicals. This paper reports some key results on how cashew nut shells (an agro waste from cashew nut processing factories) have been employed to produce several functional materials and chemicals. The materials that are highlighted include the synthesis of 3-propylphenol from cardanol and anacardic acid, some polymers prepared from CNSL components, heterogeneous catalysts prepared using CNSL as a templating agent and anacardic acid capped chalcogenide nanoparticles.

The development and application of green analytical techniques aiming at the sample preparation of complex matrices for the study of organic compounds have been growing considerably over the last 15 years. Miniaturisation, automation and solventless techniques are gaining importance in this field, associated to others, as is the case of metrics. However, the unreflected use of the so-called green analytical techniques “might lead to doing the same things better, rather than rethinking solutions altogether”. Some limits and potentialities of the green sample preparation towards sustainable separations of organic compounds using the biorefinery concept will be also discussed in this paper, a promising biobased route that can integrate sustainable extraction and purification processes in a whole complete circular unity.

The development of chemistry is closely related to the sustainable development of human civilization. The problems of exposure to chemicals on the human body are complex. Humans are potentially more susceptible to the damaging effects of chemical pollution if they are in a weakened physical or mental state (already in a state of physical or mental stress). One of the approaches, that simultaneously addresses both of the above mentioned issues, is the green chemistry concept. Governmental regulation should be seen as a framework mechanism. We see great potential in using the principles of green chemistry in the framework of the Responsible Care program. Green chemistry is a tool for the sustainable development of chemistry and the chemical industry.

Curcumin has been found to possess significant pharmaceutical activities. However, owing to its low bioavailability, there is a limitation of employing it towards clinical application. In an attempt to surmount this implication, often the choice is designing novel drug delivery systems. Herein, sterically stabilized nanoscale dispersion loaded with curcumin (nanodispersion) based on non-ionic colloidal system has been proposed. In this study, the process conditions were effectively optimized using response surface methodology (RSM) with Box–Behnken design (BBD). The suggested optimum formulation proved to be an excellent fit to the actual experimental output. STEM images illustrate that the optimal curcumin-loaded nanodispersion has spherical morphology with narrow particle size distribution. Particle size distribution study confirms that the solution pH does not affect the nanodispersion, and physical stability study shows that the colloidal system is stable over 90 days of storage at ambient conditions. More importantly, controlled release profile was achieved over 72 h and the in vitro drug release data fit well to Higuchi model ( R 2 =0.9654).

In this work silver nanoparticles (AgNPs) have been prepared from silver nitrate (AgNO 3 ) precursor using a green synthesis method at room temperature. Starch with its abundance of hydroxyl groups and its biocompatibility was used as a capping and reducing agent. The formation of AgNPs was confirmed by absorption spectroscopy with the surface plasmon resonance peak at 400 nm. The sharp reflection at (111), (200), (220) and (311) was observed by powder X-ray diffraction (XRD), which indicated the presence of cubic phase AgNPs. Transmission electron microscopy (TEM) revealed that the average size of AgNPs were between 0.5 and 4 nm with a spherical shape under optimum conditions. The nanoparticles showed a decrease in size with an increase in precursor concentration as well as the increase in capping agent concentration. The nanoparticles also showed to be bactericidal towards the tested Gram-negative (Escherichia coli ) and Gram-positive ( Staphylococcus aureus ) bacteria.

We herein report a simple large scale green synthesis route for the synthesis of silver nanoparticle (Ag-NP) multi walled carbon nanotubes (MWCNTs) hybrid nanocomposite (Ag-MWCNTs). The as-synthesized hybrid nanocomposite were characterized using UV-Vis absorption spectroscopy, Fourier transform infra-red spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction analysis (XRD) and high resolution transmission electron microscopy (HR-TEM). Raman spectroscopy analysis showed an increase in the D/G ratio of Ag-MWCNTs hybrid nanocomposites when compare with that of functionalized MWCNTs (F-MWCNTs) attributed to the presence of Ag-NPs on the surface of the F-MWCNTs. The as-synthesized Ag-MWCNTs nanocomposites showed strong antibacterial efficacy against Escherichia coli compared to the Ag-NPs and MWCNTs. The catalytic potential of the Ag-MWCNTs hybrid nanocomposite was investigated for the first time by studying the reduction of 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride at 299 K at various reaction times. The reaction follows first order kinetics with a rate constant of 5.18×10 −1 s −1 . It is believed that, the large scale synthesis of such hybrid nanocomposites via simple method using non-toxic reagent will not only enhance its antibacterial efficacy, durability and biocompatibility, it will also minimize its biotoxcity and environmental impacts.

This study reports the synthesis of gold nanoparticles from a gold precursor salt (HAuCl 4 ·3H 2 O) using Moringa oleifera bark broth, a cheap renewable material, without adding external surfactant, capping agent or template. Biomolecules responsible for reducing Au 3+ to Au 0 and stabilization of the resulting nanoparticles were extracted from the bark, and the synthesis was monitored for precursor concentration, percentage broth, pH of reaction media and reaction time. The biosynthesized nanoparticles were characterized using spectroscopic (FTIR and UV-Vis) techniques, advanced microscopic imaging (HRTEM, SEM/EDS), and Zeta potential measurements. Distinct color change from yellow to wine red was observed, indicative of the formation of gold particles at nanoscale. The SPR band was found at around 550 nm, in agreement with conventional synthetic protocols. The particles were stable with a net negative surface charge (–20 mV), a contribution associated with the protein nature of the broth. Addition of Pb 2+ to the polydisperse nanoparticle suspension resulted in a color shift, to a faint blue color, coupled with a corresponding SPR shift to higher wavelengths, depending on the concentration of Pb 2+ added. This color change is attributed to the aggregation of the colloidal particles due to complexation effects of the metal ions with the biomolecules on the surface of the nanoparticles.

Nuclear magnetic resonance (NMR) spectroscopy is one of the most important characterization tools in chemistry, however, 3/4 of the NMR active nuclei are underutilized due to their quadrupolar nature. This short review centers on the development of methods that use solid-state NMR of quadrupolar nuclei for obtaining quantitative structural information. Namely, techniques using dipolar recoupling as well as the resolution afforded by double-rotation are presented for the measurement of spin–spin coupling between quadrupoles, enabling the measurement of internuclear distances and connectivities. Two-dimensional J -resolved-type experiments are then presented for the measurement of dipolar and J coupling, between spin-1/2 and quadrupolar nuclei as well as in pairs of quadrupolar nuclei. Select examples utilizing these techniques for the extraction of structural information are given. Techniques are then described that enable the fine refinement of crystalline structures using solely the electric field gradient tensor, measured using NMR, as a constraint. These approaches enable the solution of crystal structures, from polycrystalline compounds, that are of comparable quality to those solved using single-crystal diffraction.

This short review summarizes our recent progress in fiber-shaped solar cells based on carbon nanomaterials. Highly efficient fiber-shaped solar cells based on graphene/platinum composite fibers were developed with a certified power conversion efficiency of 8.45%. Furthermore, stretchable fiber-shaped solar cells were realized by designing elastic conducting multi-walled carbon nanotube fibers with a novel rotation-translation method. These solar cells were further integrated with fiber-shaped supercapacitors to simultaneously achieve energy conversion and storage. These fiber-shaped energy devices can be woven into textile as next-generation power source for various portable electronic devices.

It has long been known that transition metals are capable of interacting with, cleaving, and mediating the functionalization of activated and unactivated carbon–hydrogen (C–H) bonds. Broadly speaking, a basic underlying principle in the fields of inorganic and organometallic chemistry is that the primary and secondary coordination spheres around a metal affect its reactivity and selectivity in elementary reactions. Hence, ligand design in transition metal catalysis has been a captivating area of research for over half a century. The discovery and development of novel ligands to promote and control otherwise recalcitrant C–H functionalization reactions is now at the forefront of organic and organometallic chemistry. Central to this line of inquiry is the interplay between ligand, substrate, metal, and reaction mechanism. This Review highlights the mechanistic details of palladium(II)-mediated C–H cleavage with mono- N -protected amino acid (MPAA) ligands. Relevant historical background is discussed, the key discoveries in catalysis with MPAAs are examined, experimental and computational studies to elucidate reaction mechanisms are presented, and possible future directions are described.

The fourth IUPAC/IUPAP Joint Working Party (JWP) on the priority of claims to the discovery of new elements 113, 115, 117 and 118 has reviewed the relevant literature pertaining to several claims. In accordance with the Criteria for the discovery of elements previously established by the 1991 IUPAC/IUPAP Transfermium Working Group (TWG), and reinforced in subsequent IUPAC/IUPAP JWP discussions, it was determined that the RIKEN collaboration has fulfilled those Criteria for element Z =113. The Dubna–Livermore–Oak Ridge collaborations claims for 115 and 117 are also in compliance. The discussion of element Z =118 will appear in a subsequent report. A synopsis of experiments and related efforts is presented along with some commentary guiding future applications of the Criteria.

The fourth IUPAC/IUPAP Joint Working Party (JWP) on the priority of claims to the discovery of new elements 113, 115, 117 and 118 has reviewed the relevant literature pertaining to several claims. In accordance with the criteria for the discovery of elements previously established by the 1991 IUPAC/IUPAP Transfermium Working Group (TWG), and reinforced in subsequent IUPAC/IUPAP JWP discussions, it was determined that the Dubna-Livermore collaboration has fulfilled those criteria for element Z =118. A synopsis of experiments and related efforts is presented.