New Pd(II), Pt(II) and Re(V) complexes of 3-aminosalicylic acid (H2salNH2) and 3-hydroxyantranilic acid (HantOH) have been prepared, cis-[Pt (HsalNH)(PPh3)2] · 0.25C2H5OH (1), trans-[PdCl(salNH2)(PPh3)2] (2), trans-[ReOI2(HsalNH2)(PPh3)] · (CH3)2CO (3), cis-[Pt(HantO)(PPh3)2] (4), trans-[PdCl(antOH)(PPh3)2] · 4H2O (5), [PdCl(antOH)(bipy)] · C2H5OH (6), [PdCl2(HantOH)2] (7) and trans-[ReOI(HantO)(PPh3)2] · (CH3)2CO (8). The crystal structure of complex 1 was determined showing chelation of HsalNH2− through the adjacent nitrogen and oxygen atoms of the amino and phenolate groups. Infrared and 1H NMR spectroscopic data for the complexes are presented.

Novel luminescent polyoxometalate anion-pillared layered double hydroxides (LDHs) were prepared by aqueous ion exchange of a Zn-A LDH precursor in nitrate form with the europium-containing polyoxotungstate anions [EuW10O36](9-), [Eu(BW11O39)(H2O)(3)](6-) and [Eu(PW11O39)(2)](11-). The hostguest interaction has a strong influence on the nature of the final intercalated species, as evidenced by elemental analysis, powder X-ray diffraction (XRD), infra-red (IR) and Raman spectroscopy, solid state magic-angle spinning (MAS) B-11 and P-31 NMR spectroscopy, and photoluminescence spectroscopy. (c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006.

A novel 1D coordination polymer, [Cu(picOH) 2 (BPE)] ( IIa ), and neutral [Cu(picOH) 2 (BPE) 2 ] ( IIb ) complexes, can be simultaneously isolated (structure II ) when neutral [Cu(picOH) 2 ] ( I ) species are axially bridged by 1,2-bis(4-pyridyl)ethane (BPE) molecules. The compound has been characterised structurally using single-crystal X-ray diffraction, elemental analysis, infrared and Raman spectroscopies and thermoanalytical measurements. In both structures the 3-hydroxypicolinate ligands are coordinated to the Cu 2+ centres through their typical N,O-chelating coordination, with the increase of coordination number in II leading to a typical Jahn–Teller distorted octahedral coordination geometry. Although the structure of I has already been reported, we have re-determined its single-crystal structure at the low temperature of 180(2) K for comparative purposes. The magnetic properties of both compounds have also been investigated.

This paper reports on the chemistry of platinum complexes containing bidentate pyridine-carboxylate (pyAc = pyridin-2-yl-acetate and picEt = pyridine-2-ethylcarboxylate, ethylpicolinate) (N,O) ligands. The pyridine-2-acetate and ethylpicolinate ligands form six- and five-membered chelates, respectively, upon formation of the Pt-carboxylate bond. In all reactions with picEt with various platinum complex starting materials, spontaneous de-esterification of the pendant carboxylate ester occurs to give directly the chelates K[PtCl(2)(pic-N,O)]-trans-[Pt(pic-N,O)(2)] and SP-4,2-[PtCl(pic-N,O)(NH(3))] without any evidence of intermediates. The de-esterification is solvent dependent, and molecular modeling was used to explain this reaction. The reactions of the geometric isomers of [PtCl(pyAc-N,O)(NH(3))] with 5'-guanosine monophosphate, 5'-GMP, and N-acetyl-l-methionine, AcMet, were investigated by NMR spectroscopy. The objective was to ascertain by model chemistry the feasibility of formation of ternary DNA-Pt-protein adducts in biology. Model nucleotide and peptide compounds were formed in situ by chloride displacement giving [PtL(pyAc-N,O)(NH(3))](+) (L = 5'-GMP or AcMet). Competitive reactions were then examined by addition of the complementary ligand L. Sulfur displacement of coordinated 5'-GMP was slow. For SP-4,3-[Pt(AcMet)(NH(3))(PyAc-N,O)](+), a rapid displacement of the sulfur ligand by 5'-GMP was observed, giving SP-4,2-[Pt(5'-GMP-N7)(pyAc-N,O)(NH(3))](+).

Two complexes with Co2+ and 3-hydroxypicolinic acid, [Co(picOH)2(H2O)2] (I) and mer-[N(CH3)4][Co(picOH)3] · H2O (II), have been synthesised and characterised using single-crystal X-ray diffraction, elemental analysis, infrared spectroscopy, and thermoanalytical measurements. The 3-hydroxypicolinate ligands are coordinated to the Co2+ centres via its typical N,O-chelating coordination fashion. While in I the presence of two coordinated water molecules leads to the formation of a neutral [Co(picOH)2(H2O)2] complex which is strongly hydrogen bonded to another four neighbouring complexes, in II the inclusion of a third picOH− ligand leads to an anionic octahedral complex, [Co(picOH)3]−, in which all the N- and O-atoms are occupying mer positions. The properties of these two compounds were further investigated by measuring their magnetic behaviour.

A novel one-dimensional zigzag lanthanopolyoxotungstoborate, H2(NH4)10[Ce2(BW11O39)2(H2O)6]·21H2O, was synthesised under ambient conditions. It is the first example of a one-dimensional polymer where Keggin-type anions containing a central boron atom are bridged by Ce3+ cations.

The crystal structure of a lanthanum polyoxotungstate complex, viz. heptaammonium disodium decatungstolanthanate hexadecahydrate, Na-2(NH4)(7)[La5O(18))(2)].16H(2)O, has been determined by single-crystal X-ray diffraction at 100 (2) K in the space group C2/c. The [La(W5O18)(2)](9-) polyoxoanion has the central La3+ cation located on a twofold rotation axis. The close packing of the polyoxoanion-supported lanthanum(III) complexes with Na+ and NH4+ cations leads to the formation of several intersecting undulating channels, where the water molecules of crystallization are located and involved in strong hydrogen bonds.

A novel supramolecular compound of europium(III), {[Eu(CH3OH)6(H2O)2][PMo12O40]}·(C14H20O5)2·(CH3OH)2·(CH3CN)2 (1) (where C14H20O5 is benzo-15-crown-5), was synthesised and structurally characterized by single-crystal X-ray diffraction, FT-IR, FT-Raman, 1H and 13C NMR, 31P MAS NMR and elemental analysis. Compound 1 crystallizes in the triclinic P1̄ space group, with a=13.821(3), b=15.417(3), c=20.786(4)Å, α=96.10(3), β=99.79(3) and γ=91.17(3)°, V=4336.6(15)Å3, Z=2 and R1(wR2)=0.0894(0.2346).

New lanthanopolyoxotungstoborates, K6-xHx[Ln(BW11O39)(H2O)3].nH2O, Ln(III) = Sm, Eu, Tb, Er, were prepared and characterized by spectroscopic methods (Fourier transform infrared, Fourier transform-Raman, 11B solid-state nuclear magnetic resonance, and photoluminescence) and elemental analysis. A layer-by-layer assembly method was employed to fabricate multilayered films containing the europium heteropolyanion and the polyelectrolytes poly(sodium 4-styrenesulfonate) and poly(diallydimethylammonium chloride). The photoluminescence behavior of these final nanostructures was investigated and compared with that of the starting Eu(III) polyoxometalate used as the building unit.

Novel luminescent materials were prepared by introducing a new Eu3+ complex of 2,6-dihydroxybenzoic acid (2,6-H2dhb) into a silica gel made by the sol–gel method. The crystal structure of the resulting complex [nBu4N]2[Eu(2,6-Hdhb)5(H2O)2] was determined using single-crystal X-ray diffraction. The compound was further characterised using FTIR, FT-Raman and elemental analysis. Photoluminescence measurements were performed for the isolated Eu(III) 2,6-dihydroxybenzoate complex and also for the related silica composite material.

A novel V-shaped polyoxotungstate is formed when Ce(IV) metal centres bridge monolacunary [PW(11)O(39)](7-) anions to an unusual 1,4-bilacunary [PW(10)O(38)](11-) anion which appears with an unprecedented bridging structural motif.

The structure of the title compound, tris­(hydro­xonium) μ12-phosphato-tetracosa-μ2-oxo-dodecaoxododecatungsten hex­akis­(benzo-15-crown-5)–methanol–water (1/1/1), (H3O)3[PW12O40]·6C14H20O5·CH3OH·H2O (where C14H20O5 is benzo-15-crown-5), has been determined at 180 K. [PW12O40]3− anions are typical of α-Keggin structures, and the [H3O·(C14H20O5)2]+ sandwich-type moieties contain a large number of short O⋯O close contacts, suggesting strong hydrogen bonding within them.

Here we report the synthesis of a polyoxotungstoeuropate anion that was found to have very interesting luminescence features. This compound was encapsulated with high molecular weight cations and then thin films were produced by Langmuir–Blodgett techniques. Photoluminescent studies were performed on the as prepared Eu(III) polyoxotungstate compound, on the surfactant encapsulated species, and on monolayers transferred to a quartz substrate using the Langmuir–Blodgett technique.

The title compound, C16H36N+·C7H5O4−·C7H6O4 or (nBu4N)+·(2,6-dhb)−·(2,6–Hdhb) [where (nBu4N) is tetra­butyl­ammonium, (2,6-dhb)− is 2,6-di­hydroxy­benzoate and (2,6-Hdhb) is 2,6-di­hydroxy­benzoic acid], crystallizes in the space group P1. The crystal structure involves alternate layers, in the c direction, of cationic [nBu4N]nn+ and anionic [(2,6-dhb)(2,6-Hdhb)]nn−. Hydro­gen bonds within the anionic layers form bridges between 2,6-Hdhb and 2,6-dhb− residues.

The new erbium(III) complex of picolinic acid (Hpic), [nBu4N][Er(pic)4]·5.5H2O, was synthesized and the crystal structure determined by single-crystal X-ray diffraction. The compound was further characterized using IR, Raman, 1H NMR and elemental analysis. The picolinate ligands (pic−) are coordinated through N,O-chelation to the erbium cations, as shown by X-ray diffraction and spectroscopic results, leading to an eight coordinate complex. Photoluminescence measurements were performed for this compound which exhibits infrared emission.

A detailed vibrational study on the isomers 2,2'-dithiodipyridine and 4,4'-dithiodipyridine was carried out. These organic ligands are of great interest as possible linkers in the fabrication of nanostructures, and therefore a study on the adsorption modes of both ligands at silver surfaces is presented. Orientational information on the 2,2-dithiodipyridine and 4,4'-dithiodipyridine molecules adsorbed on silver colloids was collected based on the SERS spectra and supported by ab initio calculations. There is evidence that both organic ligands adsorb on the silver surface through the sulfur atoms, with the aromatic rings in a tilted position. Copyright (C) 2003 John Wiley Sons, Ltd.

WO3 powders were prepared by the thermal decomposition of tungstic acids (WO3·nH2O, n=1/3, 1, 2). The tungstic acids were synthesized from WO42− aqueous solutions under a variety of conditions of pH, temperature and W(VI) concentrations. The thermal decomposition of the tungstic acids into WO3 was analysed by TG and DSC methods. Nano-sized WO3 powders with different morphological characteristics were obtained by thermal treatment of the tungstic acids at 500°C in air atmosphere. The morphologies of WO3 powders were characterised by scanning electron microscopy and infrared absorption spectroscopy. Patterns of infrared spectra were related with distinct powder morphologies.

Lanthanide complexes of 2,6-dihydroxybenzoic acid (2,6-Hdhb), namely [nBu(4)N](2)[Ln(2,6-dhb)(5)(H2O)(2)] [Ln = Sm (1) and Tb (2)], were synthesized and their crystal structures determined by single-crystal X-ray diffraction studies. The 2,6-dhb-ligand coordinates to the lanthanide cations through the carboxylate group in a monodentate or bidentate chelating coordination mode. The compounds were further characterised using IR, Raman, H-1 and C-13 NMR spectroscopy and elemental analysis. Photoluminescence measurements were performed on both compounds. In particular, the terbium complex 2 shows intense photoluminescence both in the solid state and in ethanolic solution. Compound 2 also exhibits triboluminescence. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.

New lanthanide complexes of 2-hydroxynicotinic acid (H2nicO) [Ln(HnicO)2(μ-HnicO)(H2O)]·nH2O (Ln=Eu, Gd, Tb, Er, Tm) were prepared. The crystal structures of the [Tb(HnicO)2(μ-HnicO)(H2O)]·1.75H2O (1) and [Eu(HnicO)2(μ-HnicO)(H2O)]·1.25H2O (2) complexes were determined by X-ray diffraction. The 2-hydroxynicotinate ligand coordinates through O,O-chelation to the lanthanide(III) ions as shown by X-ray diffraction and the infrared, Raman and NMR spectroscopy results. Photoluminescence measurements were performed for the Eu(III) and Tb(III) complexes. Lifetimes of 0.592±0.007 and 0.113±0.002 ms were determined for the Eu3+ and Tb3+ emitting states, 5D0 and 5D4, respectively. A value around 30% was found for the 5D0 quantum efficiency. The energy transfer mechanisms between the lanthanide ions and the ligands are discussed and compared with those observed in similar complexes involving the 3-hydroxypicolinate ligand based on the luminescence of the respective Gd3+-based complexes.

IR and Raman spectra of melamine diborate have been recorded and analysed. Band assignments are given based on the vibrations of melamine and boric acid molecules. Three sets of frequencies observed for the NH stretching mode region is ascribed to different types of hydrogen bonds in the amino groups of the triazine ring. Due to the lower symmetry of the melamine and boric acid molecules in the crystal, activation of inactive modes and lifting of the degeneracy of certain vibrational modes are observed. Lower symmetry of the melamine molecule in the crystal has resulted in the decrease of intensity of the Raman active melamine band around 1490 cm−1. All the internal modes of boric acid molecule were identified. All the ring breathing modes of melamine molecule show frequency shift towards the high wavenumber side. In other words, hydrogen bonding affects the ring breathing modes of melamine.