Nitroxide-Functionalized Graphene Oxide from Graphite Oxide

A facile method for preparing functionalized graphene oxide single layers with nitroxide groups is reported herein. Highly oxidized graphite oxide (GO=90.6%) was obtained, slightly modifying an improved Hummer’s method. Oxoammonium salts (OS) were investigated to introduce nitroxide groups to GO, resulting in a one-step functionalization and exfoliation. The mechanisms of functionalization/exfoliation are proposed, where the oxidation of aromatic alcohols to ketone groups, and the formation of alkoxyamine species are suggested. Two kinds of functionalized graphene oxide layers (GOFT1 and GOFT2) were obtained by controlling the amount of OS added. GOFT1 and GOFT2 exhibited a high interlayer spacing (d0001 = 1.12nm), which was determined by X-ray diffraction. The presence of new chemical bonds C-N (~9.5 %) and O-O (~4.3 %) from nitroxide attached onto graphene layers were observed by X-ray photoelectron spectroscopy. Single-layers of GOFT1 were observed by HRTEM, exhibiting amorphous and crystalline zones at a 50:50 ratio; in contrast, layers of GOFT2 exhibited a fully amorphous surface. Fingerprint of GOFT1 single layers was obtained by electron diffraction at several tilts. Finally, the potential use of these materials within Nylon 6 matrices was investigated, where an unusual simultaneous increase in tensile stress, tensile strain and Young’s modulus was observed

E1 and E2 Viral Proteins as Therapeutic Targets for Development of Antiviral Agents

The importance of studying the human papillomavirus (HPV) is because it is a disease that relies on 14 HPV types classified as carcinogenic high risk and that contributes to cervical cancers affecting approximately 527,600 women yearly and causing 265,387 deaths yearly, being the second mortality cause for women globally. In Mexico, 13.9% of demises are due to cervical uterine cancer (CUCA). The challenges for a vaccine that may prevent HPV occurrence are an active field for scientists with significant advances but still undergoing for a full cure to this disease. In this work, latest research trends to treat HPV are analyzed, and by means of molecular coupling analysis, a modeling and simulation process to predict interactions of leader molecules with the target for synthetic elaboration of a possible therapeutic treatment is developed. One of the main topics discussed in this chapter relates to new drug design for HPV treatment, which is related to the inhibitors of protein-protein interactions and in the protein drugs. Regarding HPV therapy development, a group of small molecules has been identified using high-performance sieving capable of interrupting HPV16 E1-E2 interaction, which helps avoid viral replication. Some of these compounds displayed nanomolar affinities and high specificity

Ether Oxidation by an Evolved Fungal Heme-Peroxygenase: Insights into Substrate Recognition and Reactivity

Ethers can be found in the environment as structural, active or even pollutant molecules, although their degradation is not efficient under environmental conditions. Fungal unspecific heme-peroxygenases (UPO were reported to degrade low-molecular-weight ethers through an H2O2-dependent oxidative cleavage mechanism. Here, we report the oxidation of a series of structurally related aromatic ethers, catalyzed by a laboratory-evolved UPO (PaDa-I) aimed at elucidating the factors influencing this unusual biochemical reaction. Although some of the studied ethers were substrates of the enzyme, they were not efficiently transformed and, as a consequence, secondary reactions (such as the dismutation of H2O2 through catalase-like activity and suicide enzyme inactivation) became significant, affecting the oxidation efficiency. The set of reactions that compete during UPO-catalyzed ether oxidation were identified and quantified, in order to find favorable conditions that promote ether oxidation over the secondary reactions

New Formulation to Synthetize Semiconductor Bi2S3 Thin Films Using Chemical Bath Deposition for Optoelectronic Applications

Abstract: Anisotropic materials possess direction dependent properties as a result of symmetry within their structure. Bismuth sulfide (Bi2S3) is an important semiconductor exhibiting anisotropy due to its crystalline and stratified structure. In this manuscript we present a new and straightforward procedure to deposit Bi2S3 thin films on soda lime glass substrates by the chemical bath deposition (CBD) technique. We studied two fundamental parameters, the time to deposit a single layer and the total number of layers deposited. The single layer deposition time was varied between 70 and 100 min and samples were coated with a total of 1, 2, or 3 layers. It is important to note that a fresh aqueous solution was used for every layer. Visible and near infra-red spectroscopy, scanning electron microscopy, X-ray photoelectrons spectroscopy, and X-ray diffraction were the characterization techniques used to study the resulting films. The calculated band gap values were found to be between 1.56 and 2.1 eV. The resulting Bi2S3 deposited films with the new formulation showed uniform morphology and orthorhombic crystalline structure with an average crystallite size of 19 nm. The thickness of the films varied from 190 to 600 nm in direct correlation to the deposition time and in agreement with the number of layers. The XPS results showed the characteristic bismuth doublet centered around 164.11 and 158.8 eV corresponding with the presence of Bi2S3. The symmetry within the Bi2S3 structure makes it a strong anisotropic crystal with potential applications in optoelectronic and photovoltaic devices, catalysis, and photoconductors among others

Fast and inexpensive synthesis of pentacene with high yield using 6,13-pentacenequinone as precursor

Pentacene is an important semiconductor in the field of organic electronics. In this work is presented an alternative synthesis procedure to obtain pentacene from 6,13-pentacenequinone as a precursor. Synthesis of pentacene was performed in two reactions, Diels-Adler cycloaddition of 6,13-pentacenequinone followed by 6,13-pentacenequinone reduction to pentacene, employing LiAlH4 as reducing agent. The products were characterized by Fourier Transform Infrared Spectroscopy (FTIR), 1H-Nuclear Magnetic Resonance Spectroscopy (1H-NMR), X-Ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and Ultraviolet–Visible Spectroscopy (UV-VIS). In this work, 6,13-pentacenequinone was synthetized with a high yield (55%) using an alternative method. The optimization process resulted in an overall reduction of reaction time while exhibiting high yield. The method presented here provides an affordable pentacene synthesis route with high purity, which can be further applied for research and development of organic electronic applications