Synthesis and Application of the Magnetic Nanocomposite GO-Chm for the Extraction of Benzodiazepines from Surface Water Samples Prior to HPLC-PDA Analysis

Nowadays, the interest in preparing new, cheap and simple adsorbents that are used in sample preparation is on the rise. Graphene oxide (GO) nanomaterials and nanocomposites have become increasingly popular due to the novel methods of syntheses that have been published. Owing to their vast specific surface area and their π-delocalized electron system they possess, they are appropriate for the adsorption of a variety of aromatic organic compounds, being utilized either as adsorbents in analytical methods or as filter materials for the removal of pollutants in water. Pharmaceutical compounds, such as benzodiazepines, end up in surface waters caused by consumption or their disposal through sewage, thus becoming pollutants. In the present study, an analytical method has been developed and validated for the determination of two model-analytes of benzodiazepines by HPLC-DAD and their sample preparation protocol which consists of the Stir bar magnetic solid phase extraction (SB-MSPE) method, evaluating therefore the nanocomposite material as a decent adsorbent. The separation took place with the usage of an analytical column C18 RP-HPLC in 10 min. For the alprazolam (ALP) and the flunitrazepam (FLT), the LODs and LOQs were 3 ng/mL and 10 ng/mL, respectively, while the relative recoveries ranged between 93.6–112.9% and the RSDs were 1.11–9.50%. Finally, the material was examined for its reusability and was found that it can be used for over eight cycles of extraction/elution.

Structure and Properties of Dyes and Pigments

Colour is one of the elements of nature that makes human life more aesthetic and fascinating in the world. Plants, animals, and minerals have been used as primary sources for colourants, dyes or pigments since ancient times. In our daily life, we know about many substances which have specific colours. These are the substances which are used as colourants i.e.; colour imparting species. Both dyes and pigments are coloured as they absorb only some wavelength of visible light. Their structures have Aryl rings that have delocalized electron systems. These structures are said to be responsible for the absorption of electromagnetic radiation that has varying wavelengths, based upon the energy of the electron clouds. Dyes are coloured organic compounds that are used to impart colour to various substrates, including paper, leather, fur, hair, drugs, cosmetics, waxes, greases, plastics and textile materials. A Dye is a coloured compound due to the presence of chromophore and its fixed property to the acid or basic groups such as OH, SO3H, NH2, NR2, etc. The polar auxochrome makes the dye water-soluble and binds the dye to the fabric by interaction with the oppositely charged groups of the fabric structure. Pigments are organic and inorganic compounds which are practically insoluble in medium in which they are incorporated. Dyes and pigments are the most important colourants used to add colour or to change the colour of something. They are widely used in the textile, pharmaceutical, food, cosmetics, plastics, paint, ink, photographic and paper industries. This chapter is devoted to the structure and properties of dyes and pigments.

Two conformational polymorphs of 4-methylhippuric acid

4-Methylhippuric acid {systematic name: 2-[(4-methylbenzoyl)amino]ethanoic acid}, a p-xylene excreted metabolite with a backbone containing three rotatable bonds (R-bonds), is likely to produce more than one stable molecular structure in the solid state. In this work, we prepared polymorph I by slow solvent evaporation (plates with Z′ = 1) and polymorph II by mechanical grinding (plates with Z′ = 2). Potential energy surface (PES) analysis, rotating the molecule about the C—C—N—C torsion angle, shows four conformational energy basins. The second basin, with torsion angles near −73°, agree with the conformations adopted by polymorph I and molecules A of polymorph II, and the third basin at 57° matched molecules B of polymorph II. The energy barrier between these basins is 27.5 kJ mol−1. Superposition of the molecules of polymorphs I and II rendered a maximum r.m.s. deviation of 0.398 Å. Polymorphs I and II are therefore true conformational polymorphs. The crystal packing of polymorph I consists of C(5) chains linked by N—H...O interactions along the a axis and C(7) chains linked by O—H...O interactions along the b axis. In polymorph II, two molecules (A with A or B with B) are connected by two acid–amide O—H...O interactions rendering R 2 2(14) centrosymmetric dimers. These dimers alternate to pile up along the b axis linked by N—H...O interactions. A Hirshfeld surface analysis localized weaker noncovalent interactions, C—H...O and C—H...π, with contact distances close to the sum of the van der Waals radii. Electron density at a local level using the Quantum Theory of Atoms in Molecules (QTAIM) and the Electron Localization Function (ELF), or a semi-local level using noncovalent interactions, was used to rank interactions. Strong closed shell interactions in classical O—H...O and N—H...O hydrogen bonds have electron density highly localized on bond critical points. Weaker delocalized electron density is seen around the p-methylphenyl rings associated with dispersive C—H...π and H...H interactions.

Utilization of electrical charges in the pores of tofu waste for hydrogen production in water

Tofu is main food in Indonesia and its waste generally pollutes the waters. This study aims to change the waste into energy by utilizing the electric charge in the pores of tofu waste to produce hydrogen in water. The tofu pore is negatively charged and the surface surrounding the pore has a positive charge. The positive and negative electric charges stretch water molecules that have a partial charge. With the addition of a 12V electrical energy during electrolysis, water breaks down into hydrogen. The test was conducted on pre-treated tofu waste suspension using oxalic acid. The hydrogen concentration was measured by a MQ-8 hydrogen sensor. The result shows that the addition of turmeric together with sodium bicarbonate to tofu waste in water, hydrogen production increased more than four times. This is due to the fact that magnetic field generated by delocalized electron in aromatic ring in turmeric energizes all electrons in the pores of tofu waste, in the sodium bicarbonate, and in water that boosts hydrogen production. At the same time the stronger partial charge in natrium bicarbonate shields the hydrogen proton from strong attraction of tofu pores. These two combined effect are very powerful for larger hydrogen production in water by tofu waste.

Delocalized electron effect on single metal sites in ultrathin conjugated microporous polymer nanosheets for boosting CO2 cycloaddition

CO2 cycloaddition with epoxides at low temperature and pressure has been broadly recognized as an ambitious but challenging goal, which requires the catalysts to have precisely controlled Lewis acid sites. Here, we demonstrate that both stereochemical environment and oxidation state of single cobalt active sites in cobalt tetraaminophthalocyanine [CoPc(NH2)4] are finely tuned via molecular engineering with 2,5-di-tert-butyl-1,4-benzoquinone (DTBBQ). Notably, DTBBQ incorporation not only enables formation of 5-nm-thick conjugated microporous polymer (CMP) nanosheets due to the steric hindrance effect of tert-butyl groups but also makes isolated cobalt sites with high oxidation state due to the presence of delocalized electron-withdrawing effect of alkene groups in DTBBQ via conjugated skeleton. Notably, when used as heterogeneous catalysts for CO2 cycloaddition with different epoxides, single cobalt active sites on the ultrathin CMP nanosheets exhibit unprecedentedly high activity and excellent stability under mild reaction conditions.

Rationalizing the diverse reactivity of [1.1.1]propellane through sigma-pi-delocalization

<p>[1.1.1]Propellane has gained increased attention due to its utility as a precursor to bicyclo[1.1.1]pentanes (BCPs) – motifs of high value in pharmaceutical and materials research – by addition of nucleophiles, radicals and electrophiles across its inter-bridgehead C–C bond. However, the origin of this broad reactivity profile is not well-understood. Here, we present a comprehensive computational study that attributes the omniphilicity of [1.1.1]propellane to a moldable, delocalized electron density, characterized by the mixing of the inter-bridgehead C–C bonding and antibonding orbitals. Reactions with anions and radicals are facilitated by stabilization of the adducts through sigma-pi-delocalization of electron density over the cage, while reactions with cations involve charge transfer that relieves Pauli repulsion inside the cage. These results provide a unified framework to rationalize propellane reactivity, opening up opportunities for the exploration of new chemistry of [1.1.1]propellane and related strained systems. </p>

Rationalizing the diverse reactivity of [1.1.1]propellane through sigma-pi-delocalization

<p>[1.1.1]Propellane has gained increased attention due to its utility as a precursor to bicyclo[1.1.1]pentanes (BCPs) – motifs of high value in pharmaceutical and materials research – by addition of nucleophiles, radicals and electrophiles across its inter-bridgehead C–C bond. However, the origin of this broad reactivity profile is not well-understood. Here, we present a comprehensive computational study that attributes the omniphilicity of [1.1.1]propellane to a moldable, delocalized electron density, characterized by the mixing of the inter-bridgehead C–C bonding and antibonding orbitals. Reactions with anions and radicals are facilitated by stabilization of the adducts through sigma-pi-delocalization of electron density over the cage, while reactions with cations involve charge transfer that relieves Pauli repulsion inside the cage. These results provide a unified framework to rationalize propellane reactivity, opening up opportunities for the exploration of new chemistry of [1.1.1]propellane and related strained systems. </p>

The Role of Mineral Sea Water Bonding Process with Graphite-Aluminum Electrodes as Electric Generator

The development of alternative ecofriendly electric energy production technology is very essential. The development of electric generator by using sea water element to boost electron jump in electrode has been studied. The aim of this research is to develop an electrode material composite that can collaborate with sea water to produce electricity. The electrodes tested are copper, aluminum, activated carbon, wood powder, and graphite electrode powder. The result shows that each electrode produces different voltage when interacting with sea water. It is caused by the patterns of the electron movement disrupted by the electron of sea water in producing a new compound. The composite of graphite-aluminum generates high electricity of about 580 mV compared to other materials. The electrical conductivity of graphite material depends on the particle size which is larger at smaller particle size. This research elucidates the role of sea water elements in boosting kinetic energy of delocalized electron on graphite resulting in an electron jump.