Volume 73, Issue 9

The crystal structure of [4-C 2 H 5 -C 6 H 4 NH 3 ] 2 ZnBr 4 ( 1 ) has been determined at 150(2) K: triclinic, P 1̅, a =724.82(2), b =1194.20(4), c =1322.26(4) pm, α =74.151(3), β =80.887(3), γ =80.434(3)°, and Z =2. There are two crystallographically independent cations in the unit cell of 1 : one has its benzene ring perpendicular to the crystallographic a axis of the unit cell and the other one has its benzene ring perpendicular to the c axis. These cations are alternatingly located along the c axis and form organic layers, and the ZnBr 4 anions form inorganic layers in between. Zn–Br···H–N hydrogen bonds are formed between cations and anions. In accordance with the crystal structure, four nuclear quadrupole resonance (NQR) lines of 81 Br were observed. The temperature dependence of the 81 Br NQR frequencies between 77 and 320 K shows a peculiar feature which is not due to a structural phase transition. The measurement of 13 C nuclear magnetic resonance spectra at around T =340 K indicates a redistribution of cations. The temperature dependence of 81 Br NQR frequencies and differential thermal analysis measurements show that [4-C 2 H 5 -C 6 H 4 NH 3 ] 2 CdBr 4 ( 2 ) undergoes a structural phase transition at around 190 K.

Reaction mixtures from Friedel-Crafts reactions can be worked up simply and economically by replacing the hydrolysis step by alcoholysis.

The ketene aminals 9a–e can be prepared from the orthoamide of propiolic acid 6a and 2-methyl-5-phenacyl-1,3,4-thiadiazoles 8a–e under mild conditions. The crystal structure analyses of 9b and 9d reveal that compounds 9 can be regarded as 1,4-dipoles (push-pull-substituted butadienes). Surprisingly, the analogous reactions of the orthoamides 6b , c with the thiadiazoles 8a–c give rise to the formation of 1,2-dihydro-pyridin-2-thiones 13a–j . The constitution of the compounds 13 was confirmed by crystal structure analyses of the compounds 13c , f , g , i .

The highly effectual synthesis of 4,6-diarylpyrimidin-2(1 H )-ones via the one-pot multicomponent reaction of acetophenones with arylaldehydes and urea in the presence of trimethylsilyl chloride and a catalytic amount of the ionic liquid N , N , N ′, N ′-tetramethylethylenediaminium- N , N ′-disulfonic acid hydrogen sulfate ([TMEDSA][HSO 4 ] 2 ) under solvent-free conditions has been described. The reaction results and conditions of the catalytic system have been compared with previously reported catalysts. [TMEDSA][HSO 4 ] 2 afforded better results in comparison with the reported catalysts in terms of one or more of these factors: yield, temperature, the reaction media, time, and generality. Moreover, a plausible reaction mechanism based on dual functionality of the catalyst has been proposed.

A novel and efficient synthesis of eight 5-aryl-1,3-dimethyl-2,4-dioxo-1,2,3,4,5,8-hexahydropyrido[2,3- d ]pyrimidine-7-carboxylic acids using a TiO 2 /SiO 2 nanocomposite with a molar ratio of 1:1 as a recyclable heterogeneous catalyst is described. The desired products, five of which are new, are formed in short reaction times (2–3 h) with high to excellent yields (94%–98%) under very moderate reaction conditions (room temperature, aqueous media).

Several 2-substituted sulfanyl benzo[ d ]thiazoles were regioselectively synthesized by the reaction of benzo[ d ]thiazole-2-thiol ( 1a ) with a variety of reagents under different basic conditions. Some 2-(2,3-disubstituted propyl sulfanyl)benzo[ d ]thiazoles were obtained from 2-(allylthio)benzo[ d ]thiazole, which was prepared by the allylation of 1a with allyl bromide in the presence of sodium hydride in dry N , N -dimethylformamide. Reaction of 1a with various pyrazolyl-quinoxaline derivatives was also investigated. Better yields and shorter reaction time were achieved for the synthesis of some derivatives by using ultrasound irradiation. The structural elucidation of all compounds was based on both analytical and spectroscopic data. The newly synthesized compounds were tested in vitro for their antitumor activity against Ehrlich ascites carcinoma (EAC) cells grown in albino mice. Doxorubicin was used as a standard antitumor antibiotic, and some compounds showed half maximal inhibitory concentration (IC 50 ) in the range 40–68 μg mL −1 .

A new zinc(II)-based coordination polymer {[Zn(5-fip)(tdbpy)]·(DMF)} n ( 1 ) {5-H 2 fip=5-fluoroisophthalic acid, tdbpy=4,4′-(2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diyl)bispyridine, DMF=dimethylformamide} has been solvothermally synthesized and structurally characterized. Single-crystal X-ray diffraction revealed that complex 1 shows a unique two-dimensional network architecture containing single-stranded [Zn(5-fip)] n and double-stranded helical [Zn(tdbpy)] n chains. The thermal and luminescence properties of complex 1 have also been studied.

Microcrystalline powders of LaCl[CO 3 ]·3H 2 O were precipitated and isolated from stoichiometric aqueous solutions of LaCl 3 ·7H 2 O and Na 2 [CO 3 ]·10H 2 O. This confirmed the surprising emergence of corresponding single crystals during a reaction of equimolar aqueous solutions of LaCl 3 ·7H 2 O and Na[N 3 ] under ambient conditions by the uptake of atmospheric CO 2 . According to the X-ray structure analysis of colorless, transparent and rectangular single-crystals, LaCl[CO 3 ]·3H 2 O adopts an orthorhombic structure, space group Pbca with the unit-cell parameters a =856.82(5), b =1598.57(9) and c =967.68(6) pm for Z=8. The tenfold coordination polyhedron around La 3+ consists of two monodentate as well as two bidentate [CO 3 ] 2− anions together with three oxygen atoms from coordinating water molecules and one chloride anion. According to DSC/TG studies and X-ray powder diffraction, LaCl[CO 3 ]·3H 2 O loses first its water and then carbon dioxide under thermal treatment up to 900°C to leave LaOCl behind. Vibrational infrared and Raman spectra confirmed the presence of H 2 O and [CO 3 ] 2− in LaCl[CO 3 ]·3H 2 O and its stepwise degradation at elevated temperatures.

The reaction of bis(diisopropylphosphano)methane disulfide with elemental iodine leads to a 1:1 adduct 1 in which only one sulfur atom of the disulfide coordinates to a diiodine molecule. The corresponding reaction of bis(diisopropylphosphano)ethane disulfide with iodine leads to the “standard” 1:2 adduct, in which both sulfur atoms coordinate to diiodine molecules.

Baltic amber shows a greenish photoluminescence upon UV illumination. When amber is dissolved in organic solvents such as ethanol, an emission spectrum is observed, which resembles that of pyrene. At higher concentrations, pyrene undergoes an aggregation, which shifts the emission to longer wavelength. In solid amber, an analogous aggregation apparently takes place. Depending on the size of the solid amber particles, a bluish ( λ max =450 nm) to greenish ( λ max =480 nm) luminescence appears.