In situ electrochemical dilatometry of carbide-derived carbons

The long life durability and extraordinary stability of supercapacitors are ascribed to the common concept that the charge storage is purely based on double-layer charging. Therefore the ideal supercapacitor electrode should be free of charge induced microscopic structural changes. However, recent in-situ investigations on different carbon materials for supercapacitor electrodes have shown that the charge and discharge is accompanied by dimensional changes of the electrode up to several percent. This work studies the influence of the pore size on the expansion behavior of carbon electrodes derived from titanium carbide-derived carbons with an average pore size between 5 and 8 Å. Using tetraethylammonium tetrafluoroborate in acetonitrile, the swelling of the electrodes was measured by in situ dilatometry. The experiments revealed an increased expansion on the negatively charged electrode for pores below 6 Å, which could be described with pore swelling.     

Phosphinomethyl Compounds: Versatile Tools in Organometallic Chemistry

Abstract

The preparation and properties of some main group and transition element compounds (Al, Si, Sn, P, Zr, Fe, Co, Ni), containing phosphinomethyl substituents, are described.     

Functional Phosphinomethyl Derivatives: Some Parallels Between Organophosphorus and Carbon Chemistry

Abstract

The reactivity of P and C in saturated and unsaturated C–P linked organophosphorus species is compared. Novel type main group element phosphine complexes and 1.3 diphospha–allyl, -allene and -butadiene compounds are obtained and characterized by NMR spectroscopy and X-ray diffraction analysis.     

Macroporous silicon and its application in sensing

Periodic silicon nanostructures can be used for different kinds of gas sensors depending on the analyte concentration. First, we present an optical gas sensor based on the classical non-dispersive infrared technique for ppm-concentration using ultra-compact photonic crystal gas cells (Pergande et al., 2011) [1]. It is conceptually based on low group velocities inside a photonic crystal gas cell and anti-reflection layers coupling light into the device. Secondly, we report on silicon nanotip arrays (Gesemann et al., 2011) [2], suitable for gas ionization in ion mobility microspectrometers (micro-IMS) having detection ranges in principle down to the ppt-range. Such instruments allow the detection of explosives, chemical warfare agents, and illicit drugs, e.g., at airports. Third of all, we describe the thermal emission properties of heated silicon photonic crystals (Gesemann et al., 2010) [3], revealing a photonic stop gap effect or strong silicon oxide emission, depending on the setup. All silicon microstructures have been fabricated by photo-electrochemical etching of silicon.     

Synthesis of the antimalarial drug FR900098 utilizing the nitroso-ene reaction

The antimalarial drug FR900098 was prepared from diethyl allylphosphonate involving the nitroso-ene reaction with nitrosocarbonyl methane as the key step followed by hydrogenation and dealkylation. The utilization of dibenzyl allylphosphonate as the starting compound allows one-step hydrogenation with dealkylation, which simplifies the preparative scheme further.     

Improved Preparation of Bicyclo-Proptlidehe

A reproducible synthesis of the title compound 6 in 10 - 20 g quantities is reported. The use of a polymeric base such as (diethylaminome-thyl)-polystyrene is exemplified in the transformation of a sensitive alcohol 4 into a labile chloride 5.