Few-layered graphene oxide (GO) was prepared using a fast and energy-saving method by microwave-assisted acid technique. The oxygenated groups existing on the GO surface were determined using UV-Vis, X-ray photoelectron and Fourier-transform infrared spectroscopies. An oxygenated group percentage of 30% in mass for the GO was observed by thermogravimetric analysis. The reduced few-layered graphene oxide (rGO) film annealed at 110 °C deposited onto a silicon/silica wafer showed expanded graphite-like structure with 0.70 nm between the rGO sheets, as determined by X-ray diffraction. This rGO film exhibited a relatively high electrical conductivity value of 7.36 × 102 S m-1 confirming the good restoration of the π-conjugated system. The prepared GO sample exhibited good stability in water from pH 4 to 12, as determined by its zeta potential, and contained 5 to 9 layers, as determined by atomic force microscopy (AFM) and transmission electron microscopy (TEM).

Polímeros condutores iônicos ou eletrólitos poliméricos constituídos por um sistema de sal dissolvido em uma matriz polimérica sólida são materiais que apresentam interesse científico e potencial tecnológico. A dissolução de sais em uma matriz polimérica amorfa ou semicristalina sólida leva a estudos sobre intrigantes aspectos estruturais, que podem ser abordados por técnicas físico-químicas diversas tais como RMN, Raman e Espectroscopia de Vida Média de Pósitrons. Os estudos estruturais são correlacionados com propriedades eletroquímicas visando à utilização desses materiais em dispositivos tais como baterias, supercapacitores e células solares. Grupos brasileiros têm gradativamente ampliado os estudos e aplicações de eletrólitos poliméricos sólidos.

Ionic conducting polymers or polymer electrolytes prepared with the addition of a soluble salt in a solid polymeric matrix are very important materials, associated with an intense research activity and technological efforts. Structural studies in a system of salt dissolved in an amorphous or semicrystalline solid polymeric matrix can be done with various techniques, such as NMR, Raman and Positron Annihilation Spectroscopy. The structural studies are correlated with electrochemical properties in order to evaluate these materials for applications in batteries, supercapacitors and solar cells. Brazilian researchers are contributing to the fundamental research and development of new applications of polymeric electrolytes.

Li(P3C2Bu t2) reage com BrCH(SiMe3)2, via adição oxidativa, formando um novo composto organofosforado de fórmula molecular P6C4Bu t4 CHSiMe3 (1). O composto 1 foi caracterizado espectroscopicamente e sua estrutura molecular determinada através de difração de raios X de monocristais. Juntamente com 1, foi caracterizado outro composto (2) com a mesma fórmula molecular, mas apresentando uma estrutura completamente saturada.

Reaction of Li(P3C2Bu t2 ) with BrCH(SiMe3)2 results in a novel organophosphorus compound with the formula, P6C4Bu t4 CHSiMe3 (1). Compound 1 was fully characterised spectroscopically and its unique molecular structure determined by single crystal X-ray diffraction. Another isomer (2) with a saturated structure was also fully characterised.

A síntese de dois novos arsadifosfóis de fórmula (AsP2C2Bu t2 )CH(SiMe3)2, a partir dos anéis aniônicos 4-arsa-1,2-difosfaciclopentadienil e 2-arsa-1,4-difosfaciclopentadienil é reportada, junto com suas caracterizações utilizando RMN de 31P. Cálculos ab initio no nível MP2/6-31G(d) de teoria foram realizados para se investigar as barreiras de inversão piramidal, estabilidade relativa e o caráter aromático de todos os possíveis isômeros dos arsadifosfóis, em fase gasosa. A distribuição termodinâmica dos isômeros está em completo acordo com os resultados experimentais. O caráter de aromaticidade obtido para os três isômeros contendo um fósforo sp³ é maior quando comparado com o 1,2,4-trifosfol, sintetizado previamente. Os efeitos dos grupos substituintes volumosos sobre a aromaticidade e as barreiras de inversão piramidal são também discutidos.

The synthesis of two new arsadiphospholes of formula (AsP2C2Bu t2 )CH(SiMe3)2, from 4-arsa-1,2-diphosphacyclopentadienyl and 2-arsa-1,4-diphosphacyclopentadienyl ring anions are reported together with their characterization by 31P NMR. Ab initio calculations at the MP2/6-31G(d) level of theory were carried out to investigate the energy barrier for pyramidal inversion about the pyramidal P and As atoms, relative stability and aromaticity character of all possible isomers in the gas phase. The thermodynamic isomers distribution is in agreement with the experimental results. The inversion barrier at the sp³ phosphorus compared to the inversion barrier found for the arsenic atom is low. This fact is directly related with the aromaticity of the rings and shows the preference of the side group for the phosphorus atom, which leads to a more aromatic ring structure. The aromaticity character found for three isomers containing a sp³-phosphorus is greater if compared with that of 1,2,4-triphosphole synthesized previously. The effects of bulky R substituents on the aromaticity and on the energy barrier for pyramidal inversion are also discussed.

The chemistry of cyclopentadiene rings has been widely studied. This review article deals with a similar chemistry of new compounds containing from 1 to 5 phosphorus atoms on the ring substituting the carbon atoms. The neutral rings containing one, two and three phosphorus atoms can be used as building blocks for the synthesis of new organic compounds containing phosphorus. These rings plus the anionic ones also show great potential as ligands in coordination chemistry. The aim of this article is to show how important this new area is and how diverse the chemistry related to a single type of ring can be.