Volume 74, Issue 7-8

The new phosphor RbKLi 2 [Li 3 SiO 4 ] 4 :Eu 2+ was synthesized by different high-temperature solid-state reactions. It is accessible from the alkali metal carbonates, SiO 2 , and Eu 2+ as a luminous active cation either in closed tantalum ampoules or by conventional solid-state reaction in nickel crucibles, under a constant flow of forming gas. The structure of the thereby received rod-shaped crystals was solved and refined on the basis of single crystal X-ray diffraction data. The compound crystallizes isostructurally to CsKNa 2 [Li 3 SiO 4 ] 4 and forms a highly condensed network of LiO 4 and SiO 4 tetrahedra [ I 4/ m (no. 87), Z  = 2, a  = 10.9508(6) and c  = 6.3334(3) Å]. It is a new member of the recently discovered family of alkali lithosilicate phosphors. Under excitation with UV to blue light, the compound exhibits interesting luminescence properties. Depending on the mode of synthesis, either green or blue luminescence of the samples is observed. Both emission profiles can be described as ultra-narrow-banded, since the full width at half maximum (fwhm) is below 0.2 eV. The green phosphor shows an emission maximum at 532 nm with a fwhm of 43.5 nm (0.193 eV) and the blue one at 474 nm with a fwhm of 24.8 nm (0.137 eV). Furthermore, the material presented here allows a more detailed localization of the luminescence center inside the structure, which may allow a better understanding of the luminescence properties of many other alkali lithosilicate phosphors.

A new 1,3-oxathiolane-based ligand, 2-(1,3-oxathiolan-2-yl)pyridine, was prepared and its coordination to lead(II) was investigated. Experiments revealed a ligand-breaking reaction during the complexation process, which leads to the formation of a 2D-coordination polymer of lead(II), [Pb( μ 3 -HME)( μ -OAc)] n ; H 2 ME: 2-mercaptoethanol. The compounds have been characterized by elemental analysis, FT-IR, 1 H NMR spectroscopy and single-crystal X-ray diffraction. X-ray analysis revealed a 2D-coordination polymer extending via acetato bridges. The lead(II) center adopts a rare PbO 4 S 3 -distorted pentagonal bipyramidal geometry with a hemidirected arrangement. Upon coordination, the thiol group of the H 2 ME ligand is deprotonated to coordinate as an anionic ligand. The network extends in sheets in the crystallographic ab plane via Pb–S–Pb and Pb–O–Pb bridges, aided by O–H⋯O hydrogen bonds.

A novel three-dimensional Cd(II) coordination framework, [Cd(PTA)(BTBP) 0.5  · H 2 O] n ( 1 ) (BTBP =  4,4′-bis(1,2,4-triazol-1-ylmethyl)biphenyl; H 2 PTA =  p -phthalic acid), has been prepared and characterized through IR spectroscopy, elemental and thermal analysis, and single-crystal X-ray diffraction. The complex is a 5-connected network with the {4 5  · 6 6 } topology based on Cd- μ 2 -H 2 O-Cd chains. It exhibits strong fluorescent emission in the solid state at room temperature. Moreover, complex 1 shows high photocatalytic activity in the degradation of methylene blue under UV irradiation.

A TiO 2 –SiO 2 nanocomposite catalyzes the one-pot cyclocondensation reaction of 1 H -indole-2,3-diones (isatins), 1,3-cyclohexanediones, and urea at T  = 70°C under solvent-free conditions with high efficiency. The present method affords the corresponding spiro products in high yields and short reaction time. The unique features of the TiO 2 –SiO 2 nanocomposite are high catalytic activity, ease of preparation, non-toxicity, low loading, and recyclability.

A new polymeric silver(I) complex of imidazolidine-2-thione (Imt), {[Ag 2 (Imt) 3 ](NO 3 ) 2 } n ( 1 ) was prepared and its structure was determined by single-crystal X-ray diffraction analysis. The silver atoms form infinite chains with two Ag − S(Imt) − Ag strands linked to each other by sulfur atoms of μ 4 -Imt ligands. Each silver(I) ion is bound to four sulfur atoms of bridging Imt ligands in a distorted tetrahedral environment. The crystal structure is stabilized by hydrogen bonding and weak argentophilic interactions. The hydrogen bonded nitrate ions connect the 1D chains to generate a 2D layer structure.

Basic values for the volume increments are calculated for pseudohalide anions such as N 3 − , CN − , OCN − , SCN − and C(CN) 3 − using Biltz’s methods and Biltz volumes for monoatomic cations. The results are compared within the cohort and with the reported data for halide anions and for N(CN) 2 − .

The salt [NHEt 3 ][Re(I)(quinaldate)(CO) 3 Cl] was obtained by the reaction of Re(CO) 5 Cl with quinaldic acid and triethylamine in toluene. The crystal structure analysis of this salt revealed the presence of the complex anion [Re(quinaldate)(CO) 3 Cl] − , with the d 6 Re(I) metal center in a pseudo-octahedral environment. The electronic spectra in absorption and emission exhibit bands which are attributed to quinaldate IL and CT transitions at comparable energies. The longest-wavelength emission originates from a Re(I) to quinaldate MLCT triplet, which can be quenched in solution by oxygen or triethylamine.

Hexagonal α-Al 2 O 3 platelets with about 1-μm diameter and 0.2-μm thickness are prepared by the calcination of a milled Al(OH) 3 precursor with NH 4 F and NH 4 Cl additives. The influences of the ball milling treatment and the composite additive on the microstructure of α-Al 2 O 3 micro-powders are studied. The results indicate that the particle size distribution of α-Al 2 O 3 is highly dependent on the aggregate size of the Al(OH) 3 precursor and that the morphology of α-Al 2 O 3 can be significantly favored by the addition of 5 wt.% NH 4 F and 5 wt.% NH 4 Cl as additives. The growth velocity of the (0001) plane is significantly reduced because of the accelerated growth rate of other crystal faces caused by the increase of gas phase mass transfer. The combined effect of composite additives and precursor ball milling treatment leads to the generation of well-developed α-Al 2 O 3 platelets with uniform size distribution.

Propyne iminium triflates 1 – 6 react as dipolarophiles in thermal [3 + 2]-cycloadditions with sufficiently electron rich organoazides to form 1,4,5-trisubstituted 1,2,3-triazoles with iminium functionalization. The reactions require rather strong thermal activation, but can be accelerated by microwave irradiation. The regioselectivity of the cycloaddition at the internal acetylenic bond of 3-cyclopropylpropyne and 3-arylpropyne iminium ions ( 1 – 3 and 4 , respectively) is very high, but is lowered in the presence of sterically demanding substituents at the opposite end of the iminium-substituted C,C triple bond. The iminium-functionalized triazoles can easily be transformed into neutral compounds; herein reported is the formation of triazolyl ketones 10 by hydrolysis and of tertiary triazolyldimethyl amines 12 by LiAlH 4 reduction. When the reduction is performed with sodium boranate or sodium cyanoboranate, amine–borane complexes 15 and 16 are obtained.

Novel reactions of ( Z )-2-amino- N ′-arylbenzimidamides ( 1a , b ) are described. When 1a , b are reacted with diphenic, phthalic and succinic anhydrides, in dry ethyl alcohol under reflux conditions, the 4-arylaminoquinazoline-2-carboxylic acid derivatives ( 3a–f ) were formed in good yields. The structures of the products were assigned on the basis of their spectroscopic and analytical data.

We experimentally investigated the optimum dosage of casein superplasticizer (SP) in self-leveling underlayments (SLUs). The undersaturated adsorption state of casein in cement pore solution was characterized by zeta potential measurements. Different amounts of casein were dosed in SLU pastes and their dispersion performance was investigated by a mini slump test. Flow values of the SLU pastes were found to increase with casein dosage, but an obvious segregation of the pastes was observed at high dose levels of SP. At an SP dosage of 0.12 wt.% bwob (by weight of binder), a homogeneous SLU paste with a spread flow of >15 cm over a time span of 30 min was obtained, which was identified as the optimum casein dosage for SLUs. Casein was found to adsorb significantly onto the surface of cement, thus producing strong dispersive power at low dose levels.

The isothermal section of the Gd-Ni-In system at T  = 870 K was constructed by means of X-ray powder diffraction and EDX analyses. Thirteen ternary compounds, namely GdNi 9 In 2 (YNi 9 In 2 type), Gd 1−1.22 Ni 4 In 1-0.78 (MgCu 4 Sn type), GdNiIn 2 (MgCuAl 2 type), Gd 4 Ni 11 In 20 (U 4 Ni 11 Ga 20 type), GdNi 1.0-0.7 In 1.0-1.3 (ZrNiAl type), Gd 2 Ni 2 In (Mn 2 AlB 2 type), Gd 2 Ni 1.78 In (Mo 2 FeB 2 type), Gd 11 Ni 4 In 9 (Nd 11 Pd 4 In 9 type), Gd 12 Ni 6 In (Sm 12 Ni 6 In type), Gd 6 Ni 2.39 In 0.61 (Ho 6 Co 2 Ga type), Gd 14 Ni 3.29 In 2.71 (Lu 14 Co 3 In 3 type), Gd 3 Ni 0.05 In 0.95 (AuCu 3 type) and ~Gd 6 Ni 2 In exist in the Gd-Ni-In system at this temperature. The substitution of Ni for In was observed for GdNi 1.0-0.7 In 1.0-1.3 and of In for Gd for Gd 1-1.22 Ni 4 In 1-0.78 . Besides, Gd can enter the structure of NiIn (CoSn type) leading to a solid solution Gd 0-0.14 NiIn 1-0.98 .

A new Co(II) complex, [Co(pta)(H 2 O) 2 ] n ( 1 ), with the 2-(4-pyridyl)-terephthalate ligand (pta 2− ) has been synthesized and structurally and magnetically characterized. Single crystal X-ray analysis indicates that the unique Co(II) ion in the asymmetric unit of 1 displays stretched octahedral geometry. Compound 1 presents a bimetallic layer structure which is further expanded to a 3D supramolecular network through hydrogen bonding interactions. Magnetic measurements have revealed the temperature-dependent existence of antiferromagnetic and ferromagnetic interactions in compound 1 .