Redox potentials of photosensitive cyclometalated RuII derivatives of 2-phenylpyridine or 2-(4-tolyl)pyridine are controllably decreased by up to 0.8 V within several minutes. This is achieved by irradiation of the ruthena(II)cycles cis-[Ru(o-X-2-py)(LL)(MeCN)2]PF6 (2, X = C6H4 (a) or 4-MeC6H3 (b), LL = 1,10-phenanthroline or 2,2'-bipyridine). The cis geometry of the MeCN ligands has been confirmed by the X-ray structural studies. The sigma-bound sp2 carbon of the metalated ring is trans to LL nitrogen. Complexes 2 are made from [Ru(o-X-2-py)(MeCN)4]PF6 (1) and LL. This "trivial" ligand substitution is unusual because 1a reacts readily with phen in MeCN as solvent to give cis-[Ru(o-C6H4-2-py)(phen)(MeCN)2]PF6 (2c) in a 83% yield, but bpy does not afford the bpy-containing 2 under the same conditions. cis-[Ru(o-C6H4-2-py)(bpy)(MeCN)2]PF6 (2e) has been prepared in CH2Cl2 (74%). Studies of complexes 2c,e by cyclic voltammetry in MeOH in the dark reveal RuII/III quasy-reversible redox features at 573 and 578 mV (vs Ag/AgCl), respectively. A minute irradiation 2c and 2e converts them into new species with redox potentials of -230 and 270 mV, respectively. An exceptional potential drop for 2c is accounted for in terms of a photosubstitution of both MeCN ligands by methanol. ESR, 1H NMR, and UV-vis data indicate that the primary product of photolysis of 2c is an octahedral monomeric low-spin (S = 1/2) RuIII species, presumably cis-[RuIII(o-C6H4-2-py)(phen)(MeOH)2]2+. The primary photoproduct of bpy complex 2e is cis-[RuII(o-C6H4-2-py)(bpy)(MeCN)(MeOH)]+, and this accounts for a lower decrease in the redox potential. Irradiation of 2c in the presence of added chloride affords [(phen)(o-C6H4-2-py)ClRuIIIORuIVCl(o-C6H4-2-py)(phen)]PF6, a first mu-oxo-bridged mixed valent dimer with a cyclometalated unit. The structure of the dimer has been established by X-ray crystallography.

Zeolitic material was synthesised from¯y ash using two different conversion methodologies. The two conversion products obtained were: (a) impure zeolitic material obtained by direct conversion from different Spanish¯y ashes, and (b) a high purity 4A±X zeolite blend synthesised from the silica extracts obtained from the Meirama¯y ash (NW Spain). The zeolitic material was tested for potential application as an ion exchanger to decontaminate waters containing high concentrations of ammonium and heavy metals. Preliminary results show high cation uptake ef®ciencies (up to 4.7 meq g À1 ) which allowed fast decontamination of different types of industrial or acidic mine waste waters. The CO 2 , SO 2 and NH 3 sorption capacity of several zeolitic products was also determined and very promising results were obtained for the A4±X blend. Sorption capacity values of up to 74, 297, and 111 mg g À1 for CO 2 , SO 2 and NH 3 respectively were obtained for the zeolitic material synthesised from silica extracts from¯y ash and a high-aluminate waste water.

Tin(IV) complexes 2a-q derived from pyridine Schiff bases were prepared and characterized. Four complexes of this series were evaluated in vitro against different carcinogenic cell lines; besides their anti-inflammatory and antioxidant properties were also tested. Combination of mass spectrometry, multinuclear NMR and Xray diffraction techniques evidenced the formation of heptacoordinated monomeric species. The X-ray diffraction analysis of 2a, 2b, 2i, 2j and 2n led to establish the heptacoordination around the tin atom in solid state and also revealed that the ligand occupies the equatorial positions of the distorted pentagonal bipyramidal geometry and the two alkyl or aryl groups the axial positions. The in-vitro study for complexes 2a-d against six tumor cell lines showed varied antiproliferative activity, the IC 50 for all tested complexes was lower than that of the cisplatin. Compounds 2a-d also exhibited anti-inflammatory activity where complex 2c resulted to be more active (IC 50 ‫11.0؍‬ m mM) than the indomethacin IC 50 ‫72.0؍‬ m mM which was used as reference. The antioxidant activity in rat brain homogenate on inhibition of thiobarbituric acid reactive substances (TBARS) indicated that 2c (IC 50 ‫77.1؍‬ m mM) is more active than the quercetine (4.11 m mM) and a a-tocopherol (IC 50 ‫90.965؍‬ m mM).

The potential value of zeolitic materials (ZM) obtained from a hazardous waste, such as coal fly ash, for the retention of NH(4)(+) present in liquid effluents from a Sewage Treatment Plant (STP) is studied. A wastewater sample was taken from an STP in Zaragoza (Spain) after conventional treatment at the Plant. The water was treated with different amounts of three ZM: NaP1 zeolite, K-F zeolite and K-Chabazite/K-Phillipsite zeolites all of them in powdered and granulated state. The wastewater was treated by two kinds of processes: continuous stirring batch experiments with powdered ZM, and fixed packed bed of granulated ZM in a column. The powdered materials reduced about 80% of NH(4)(+) from wastewater, even in the presence of Ca(2+), which competes with NH(4)(+) for the cation exchange sites in zeolites. Around 70% of NH(4)(+) reduction was achieved with granulated materials. In both cases, moderate ZM/wastewater ratios had to be used to achieve those results, with K-zeolites slightly less effective in NH(4)(+) retention.

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As a first step towards hydatid disease control, the in vitro survival of protoscolices of Echinococcus granulosus was investigated for various media and temperatures. Higher percentage survival was obtained than previously reported: at 4 degrees C, 100% survival was obtained for 20 days in medium 199 (GIBCO) and for 25 days in hydatid fluid from the host of origin. Maximal survival was 30% at 55 days in these conditions. Flame cell activity was the criterion of choice for viability. At 37 degrees C survival rates were lower and morphological changes in protoscolices were observed.

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Mild electrophilic C(sp2)-H cyclometalation of 2-phenylpyridine and N,N-dimethylbenzylamine by the chloro-bridged osmium(II) dimer [OsCl(micro-Cl)(eta6-C6H6)]2 in acetonitrile affords cyclometalated pseudotetrahedral OsII complexes [Os(C approximately N)(eta6-C6H6)(NCMe)]PF6 (C approximately N=o-C6H4py-kappa C,N (2) and o-C6H4CH2NMe2-kappa C,N (5), respectively) in good to excellent yields. The cyclometalation reactions are super sensitive to the nature of an external base. Sodium hydroxide is essential for cyclometalation of 2-phenylpyridine, but NaOH retards metalation of N,N-dimethylbenzylamine, the tertiary amine being self-sufficient as a base. Further reactions of compounds 2 and 5 with 1,10-phenanthroline or 2,2'-bipyridine (N approximately N) lead to the substitution of the eta6-bound benzene to produce octahedral species [Os(C approximately N)(N approximately N)(NCMe)2]PF6 or [Os(C approximately N)(N approximately N)2]PF6 in MeCN or MeOH as solvent, respectively. The cis configuration of the MeCN ligands in [Os(C approximately N)(phen)(NCMe)2]PF6 has been confirmed by an X-ray crystallographic study. Electrochemical investigation of the octahedral osma(II)cycles by cyclic voltammetry showed a pseudoreversible MIII/II redox feature at (-50)-(+109) and 190-300 mV versus Ag/AgCl in water and MeCN, respectively. As a possible application of the compounds, a rapid electron exchange between the reduced active site of glucose oxidase enzyme from Aspergillus niger and the electrochemically generated OsIII species has been demonstrated. The corresponding second-order rate constants cover the range (0.7-4.8)x10(6) M(-1) s(-1) at 25 degrees C and pH 7.