A range of complexes based on the high-nuclearity [W36] isopolyoxotungstate cluster, [H12W36O120]12-, with a triangular topology has been isolated by using the organic cation, protonated triethanolamine. In analogy to an 18-crown-6 crown ether with six oxygen donors on a ring, the cluster can form alkali and alkaline earth metal complexes [M within W36] (M = K+, Rb+, Cs+, NH4+, Sr2+ and Ba2+, 1...

In an attempt to search for mixed alkaline-earth and transition metal pyroborates, the title compound, barium manganese(II) pyroborate, has been synthesized by employing a flux method. The structure of BaMnB2O5 is composed of MnO5 square pyramids that form Mn2O8 dimers by edge-sharing and of pyroborate units ([B2O5]4-) that are composed of two corner-sharing trigonal-planar BO3 units. These bui...

Potassium and calcium salts are well known catalysts for the reaction between carbon and O2. Current airport runway deicing agents typically use formulations containing alkali or alkaline-earth metals (see C&E News, 01/01/01, p. 30). Very effective oxidation protection of aircraft brakes is thus of great practical and fundamental interest. Phosphorus and boron compounds are known to inhibit unc...

Bi-chromophoric compounds linked to linear polyether N,N'-[oxybis(3-oxapentamethyleneoxy-2-phenyl)]-bis(1-anthracenecarboxamide) (1(4)) and its analogues (1(5), 2(4) and 2(5)) were synthesized. Their photochemical properties and complexation actions were investigated in acetonitrile. These fluoroionophores have shown weak emissions in the absence of guest ions, resulting in a twisted intramolec...

Suitable single crystals of the title compound, barium dicobalt(II) bis-[orthoarsenate(V)], were prepared under hydro-thermal conditions. This phase belongs to a series of compounds with general formula AM(2)(XO(4))(2), where A = alkaline earth metal, M = Mg or a divalent first-row transition element, and X = P, As or V. BaCo(2)(AsO(4))(2) is isotypic with BaNi(2)(XO(4))(2) (X = P, V or As) and...

Novel 2-benzothiazole-, 4-pyridine-, and 2- and 4-quinoline-based styryl dyes containing an N-methylbenzoaza-15(18)-crown-5(6)-ether moiety were synthesized. A detailed electronic spectroscopy study revealed high performance of these compounds as optical molecular sensors for alkali and alkaline-earth metal cations. They were shown to considerably surpass analogous chromoionophores based on N-p...

Novel bi-chromophoric naphthalimide derivatives containing benzo-15-crown-5 and N-phenyl-aza-15-crown-5 receptor moieties BNI2 and BNI3 were designed and prepared. Significant Förster resonance energy transfer (FRET) from donor (D) amido-naphthalimide to acceptor (A) amino-naphthalimide chromophores as well as photoinduced electron transfer (PET) between the N-aryl receptor and amido-naphthalim...

A chiral, tetradentate polyether ligand with a trans-1,2-cyclohexanediyl backbone, bis(methoxyethoxy)-trans-1,2-cyclohexane (5), was synthesized as both a racemate and the (S,S) enantiomer. 5 was found to form stable adducts with alkaline earth metal amides [M{N(SiMe(3))(2)}(2)(thf)(x)] (M = Mg (x = 0), Ca (x = 2) and Sr (x = 2/3)), [Ca{N(SiHMe(2))(2)}(2)(thf)] as well as with hydrocarbyl compo...

In our attempt to search for mixed alkaline-earth and transition metal arsenates, the title compound, barium dimanganese(II) bis-(arsenate), has been synthesized by employing a high-temperature RbCl flux. The crystal structure of BaMn2(AsO4)2 is made up of MnO6 octa-hedra and AsO4 tetra-hedra assembled by sharing corners and edges into infinite slabs with composition [Mn2(AsO4)2]2- that extend ...

Developing of new rare-earth (RE)-doped optical fibres for power amplifiers and lasers requires continuous improvements in the fibre spectroscopic properties (like shape and width of the gain curve, optical quantum efficiency, resistance to spectral hole burning and photodarkening,...). Silica glass as a host material for fibres has proved to be very attractive. However some potential applicati...