Preparation and structural characterization of a novel polyoxometalate (POM), [(P(2)W(15)Ti(3)O(60.5))(4)(NH(4))](35-) 1, i.e., an encapsulated NH(4)(+) cation species in the central cavity of a tetramer (called the Dawson tetramer) constituted by trititanium(IV)-substituted α-Dawson POM substructure, are described. POM 1 was synthesized by several different methods and unequivocally characterized by complete elemental analysis, thermogravimetric and differential thermal analysis (TG/DTA), FTIR spectroscopy, solution ((15)N{(1)H}, (31)P, (183)W) NMR spectroscopy, and X-ray crystallography. First, POM 1 was synthesized by a reaction of NH(4)Cl in aqueous solution with a precursor, which was derived by thermal treatment of a monomeric triperoxotitanium(IV)-substituted Dawson POM, [α-1,2,3-P(2)W(15)(TiO(2))(3)O(56)(OH)(3)](9-) 2, for 3 h in an electric furnace at 200 °C. The encapsulated NH(4)(+) cation in 1 was confirmed by (15)N{(1)H} NMR measurement and X-ray crystallography. As another synthesis of 1, a direct exchange of the Cl(-) anion encapsulated in [{α-1,2,3-P(2)W(15)Ti(3)O(57.5)(OH)(3)}(4)Cl](25-) 3 with the NH(4)(+) cation was attained by neutralizing an aqueous solution containing 3 with the addition of aqueous NH(3) (the initial pH of ca. 2-2.5 was changed to 6.4), followed by adding NH(4)Cl. It has been clarified that the conditions as to whether the anion or the cation is encapsulated in the central cavity of the Dawson tetramer were significantly related to the protonation/deprotonation of the bridging oxygen atoms on the intramolecular surface, Ti-O-Ti/Ti-OH-Ti sites constituting the Dawson subunits.

Novel cross-linked fluoroalkyl end-capped trimethoxyvinylsilane oligomeric nanoparticles [RF–(VM-SiO2)n–RF]-encapsulated 1,1′-bi(2-naphthol) (BINOL) were prepared by the hydrolysis of fluoroalkyl end-capped trimethoxyvinylsilane oligomer in the presence of BINOL under alkaline conditions. RF–(VM-SiO2)n–RF-encapsulated BINOL nanocomposite thus obtained afforded no weight loss corresponding to the presence of BINOL in the composite at 800 °C. Interestingly, RF–(VM-SiO2)n–RF/BINOL nanocomposite did not show absorption peaks before calcination however this nanocomposite was found to exhibit similar absorption and fluorescence peaks to those of the parent BINOL after calcination at 800 °C. More interestingly, RF–(VM-SiO2)n–RF/BINOL nanocomposite after calcination exhibited a releasing characteristic into methanol although before calcination this nanocomposite showed no such characteristic at all. In particular, FT-IR spectra of the released molecules showed typical bands related to both the parent BINOL and silica gel, indicating that the released guest molecules should be thermally stable even at 800 °C through the architecture of rigid BINOL-containing silica gel matrices.

The major alkaloid of a Fijian Melodinus sp. (family Apocynaceae) has been identified as (+)-scandine (1). The crystal structure and absolute configuration of the acetone solvate of (+)-scandine hydrobromide have been determined by X-ray diffraction; diffractometer data at 295 K were refined by block diagonal least squares to a residual of 0,037 (2657 'observed' reflections). Crystals of the hydrobromide are monoclinic, P 2,, a 9.496(3), b 14.561(5), c 9.339(3) A, p 115.39(2)", Z 2.Although the cations of (+)-scandine hydrobromide and (+)-N-methylmeloscine bromide have the same skeleton and the same absolute configuration, they have different conformations; this appears to be due to the steric effect of the N-methyl group in the latter cation.

A novel trititanium(IV)-substituted Wells-Dawson polyoxometalate (POM)-based organometallic complex, i.e., a dimeric POM containing two bridging Cp*Rh(2+) groups (Cp* = C5Me5) or [{α-P2W15Ti3O60(OH)2}2(Cp*Rh)2](16-) (D-1) with Ci symmetry, was synthesized in an analytically pure form by a 1:2 -molar ratio reaction of the organometallic precursor [Cp*RhCl2]2 with the separately prepared, monomeric trititanium(IV)-substituted Wells-Dawson POM, "[P2W15Ti3O59(OH)3](9-)" (M-1). The crystalline sample (NaK-D-1) of the water-soluble, mixed sodium/potassium salt of D-1 was obtained in the 14.7% yield, which has been characterized by complete elemental analysis, TG/DTA, FTIR, single-crystal X-ray structure analysis, and solution ((183)W, (31)P, (1)H and (13)C{(1)H}) NMR spectroscopy. Single-crystal X-ray structure analysis revealed that the two species of the protonated Wells-Dawson subunits, "[P2W15Ti3O60(OH)2](10-)" were bridged by the two Cp*Rh(2+) groups, resulting in the an overall Ci symmetry. The Cp*Rh(2+) groups were linked to the two terminal oxygen atoms of the titanium(IV) sites and one edge-sharing oxygen atom of the surface Ti-O-Ti bond. The (183)W NMR of D-1 dissolved in D2O showed that its solution structure was represented as a dimeric POM with a formula of [{α-P2W15Ti3O60(OH)3}2{Cp*Rh(OH)}2](16-) (D-2) with Ci (or S2) symmetry. A trititanium(IV)-substituted Wells-Dawson POM-supported organometallic complex has never been reported so far, and thus D-1 in the solid state and D-2 in solution are the first example of this type of complex.

Keywords: Polyoxometalates / Titanium / TungstenPowder and crystalline samples of the monomer (Et 2 NH 2 ) 5 [α-PW 11 TiO 40 ]·2H 2 O (EtN-1) and a crystalline sample of the μoxo dimer (Et 2 NH 2 ) 8 [(α-PW 11 TiO 39 ) 2 O]·6H 2 O (EtN-2) of mono-titanium(IV)-containing α-Keggin polyoxometalates (POMs) were prepared and characterized by elemental analysis, thermogravimetry/differential thermal analysis (TG/DTA), FTIR, single-crystal X-ray crystallography, and[a]