A calix [4]arene modified carbon paste electrode was used for trace determination of copper. The study of the preconcentration of copper as well as the other heavy metal ions at the modified electrode, with subsequent measurement by differential pulse anodic stripping voltammetry (DPASV), indicates the efficient open-circuit accumulation of the analytes onto the electrode. Many parameters such as the composition of the paste, pH, preconcentration time and stirring rate influence the response of the measurement. The procedure was optimized for copper determination. For a 10-minute preconcentration time at pH 6.5 -7.5, the detection limit (LOD) was 1.1 mg L À1. The optimized method was successfully applied to the determination of copper in tap water sample by means of standard addition procedure. The copper content of the sample was comparable with the result obtained with AAS method.

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Magnesium porphyrazines substituted with eight 9-anthracenecarboxy groups on the peripheral positions have been synthesized by esterification of octakis(hydroxyethylthio) derivative with 9-anthracenecarboxy lie acid. Metal-free derivative as well as zinc porphyrazine were also isolated. These porphyrazines have been characterized by elemental anaysis, 'H NMR, 13 C NMR, U.V. -vis. spectral data. In the case of compounds carrying porphyrazine and anthracene entities together in the same molecule and also in the case of mixtures made up of these electron-rich moieties, the emission of anthracene has been quenched by the porphyrazine core. The detected emission is related only to porphyrazine. Therefore, in both cases energy transfer has been realized from electronically excited anthracene (donor) units to the porphyrazine moiety (acceptor). These materials can be proposed to provide antenna effect to facilitate energy transfer and light harvesting.

In the title compound, [Zn(C32H40N8S8)], the ZnII ion is coordinated by four N atoms in a slightly distorted square-planar environment. In addition, there is a Zn⋯S contact involving a symmetry-related S atom which, when considered, forms a pseudo-square-pyramidal coordination with respect to the ZnII ion. Three of the ethyl groups are disordered over two sites with occupancy ratios of 0.841 (10):0.159 (10), 0.802 (10):0.198 (10) and 0.457 (13):0.543 (13). Weak intra­molecular C—H⋯N and C—H⋯S inter­actions contribute to the stability of the mol­ecular conformation. Inter­molecular C—H⋯S contacts, weak C—H⋯π inter­actions and π–π stacking inter­actions [centroid–centriod distances = 3.832 (4) and 3.850 (5) Å] contribute to the stabilization of the crystal structure.