The effects of substitution on tetrakis­(substituted imidazole)­copper(II) tri­fluoro­methane­sulfonates

The organic ligands 4‐methyl‐1H‐imidazole and 2‐ethyl‐4‐methyl‐1H‐imidazole react with Cu(CF₃SO₃)₂·6H₂O to give tetrakis(5‐methyl‐1H‐imidazole‐κN³)­cop­per(II) bis­(tri­fluoro­methane­sulfonate), [Cu(C₄H₆N₂)₄](CF₃SO₃)₂, and aqua­tetrakis(2‐ethyl‐5‐methyl‐1H‐imidazole‐κN³)copper(II) bis(tri­ fluoro­methane­sulfonate), [Cu(C₆H₁₀N₂)₄(H₂O)](CF₃SO₃)₂. In the former, the Cu atom has an elongated octahedral coordination environment, with four imidazole rings in equatorial positions and two tri­fluoro­methane­sulfonate ions in axial positions. This conformation is similar to those in the analogous complexes tetrakis­(imidazole)­cop­per(II) tri­fluoro­methane­sulfonate and tetrakis(2‐methyl‐1H‐imidazole)­cop­per(II) tri­fluoro­methane­sulfonate. In the second of the title compounds, the ethyl groups block the central Cu atom, and a square‐pyramidal coordination environment is formed around the Cu atom, with the substituted imidazole rings in the basal positions and a water mol­ecule in the axial position.     

Trace determination of platinum-II. Analysis in ores by pulse polarography after fire-assay collection

A pulse-polarography method is described for the determination of traces of platinum in ores after fire-assay separation and preconcentration. The silver bead from the fire assay is dissolved and treated with ammonia and ethylenediamine to produce a sensitive catalytic polarographic wave. Measurement of the wave by differential pulse polarography allows determination of Pt with a detection limit of 0.0025 ppm. Platinum in ore samples was determined in the range 0.1-0.9 ppm and a correlation coefficient of 0.98 was obtained on comparison with AAS results.     

Context-aware systems — a primer for user-centred services

Convergence in the telecommunications industry provides an excellent platform and opportunity for new context-aware services. Context awareness, i.e. being able to harvest environmental information and use it to meet or anticipate user needs, is a key enabler for personalised applications and services that will be attractive to users in the future. This paper explores relevant research studies that have been undertaken, and proposes a new architecture for realisation of a context-aware system.     

Class of majority decodable real-number codes

A majority decoding algorithm for a class of real-number codes is presented. Majority decoding has been a relatively simple and fast decoding technique for codes over finite fields. When applied to decode real-number codes, the robustness of the majority decoding to the presence of background noise, which is usually an annoying problem for existing decoding algorithms for real-number codes, is its most prominent property. The presented class of real-number codes has generator matrices similar to those of the binary Reed-Muller codes and is decoded by similar majority logic