Volume 60, Issue 11

Potassium and rubidium oxoruthenates, A 2 RuO 4 , were synthesized from the alkali peroxides/ hyperoxides and ruthenium dioxide. Both compounds crystallize in the orthorhombic space group Pnma (no. 62), (K 2 RuO 4 : a = 7.673(2), b = 6.153(2) and c = 10.564(3)Å , Z = 4, 796 unique reflections, R=3.5%; Rb 2 RuO 4 : a =8.106(2), b = 6.270(1) and c =11.039(2)Å , Z =4, 889 unique reflections, R = 3.6%). The crystal structures, as determined from single crystal data, are of the β - K 2 SO 4 type. Magnetic measurements reveal that both compounds are paramagnetic down to temperatures of around 60 K and further exhibit antiferromagnetic transitions, at around TN = 9 K for Rb 2 RuO 4 , and two transitions with TN = 14 K and 4 K for K 2 RuO 4 . The magnetic moments as determined applying Curie-Weiss law for both compounds are 2.68 μ B , thus confirming the oxidation state +6 of ruthenium.

The interaction between triethylenetetraminehexaacetic acid, TTHA, and three divalent metal ions Cd(II), Co(II) and Pb(II) was investigated potentiometrically in two 1 : 1 and 2 : 1 metal to ligand mole ratio systems. The overall equilibrium formation constants were computed by the BEST program. The species distribution diagrams were also depicted using the SPE program. Eight protonation constants were obtained which were assigned for the protonation of nitrogen donors at first and carboxylic groups in continuation. For the 1 : 1 metal to ligand ratio, the main species in the middle pH region is MLH, the concentration of which decreases slowly on going to the basic region. The main complex at basic pH is ML, which becomes the sole species at pH above 10. In the 2 : 1 system, only the M 2 L species remain intact in a broad range from pH = 4 to the basic region. Compared to EDTA, TTHA has a higher relative stability with cadmium and so, can potentially present as a suitable candidate for chelation therapy

C-lithiated bis(tert-butyl-methyl)ketazine reacts with halosilanes to give the monosilylketazines, t-Bu(Me)C=N-N=C(t-Bu)-CH 2 R, (1 - 7). (1: R = SiMe 3 ; 2: R = SiClMe 2 ; 3: R = SiClMePh; 4: R = Cl 2 SiPh; 5: R = SiCl 3 ; 6: R = SiMe 2 Ph; 7: R = F 2 SiN(t-Bu)SiMe 3 ). The bis(ketazinyl)silanes [t-Bu(RCH 2 ) C = N-N = CCH 2 -t-Bu] 2 SiMe 2 8, 9 are formed in the reaction of the same lithiated ketazine or 1 with Cl 2 SiMe 2 in a molar ratio of 2 : 1, (8: R = H; 9: R = SiMe 3 ). Di(silyl)ketazines (10, 11) are obtained from lithiated 1 and ClSiMe 2 Ph in a molar ratio of 1:1 and from dilithiated ketazine with F 2 Si(i-Pr) 2 in a molar ratio of 1 : 2 [t-Bu(RH 2 C)C=N-N=C(CH 2 R’)t-Bu, 10: R = SiMe 3 , R’ = SiMe 2 Ph; 11: R,R’ = FSi(i-Pr) 2 ]. The tris(ketazinyl)fluorosilane 12 is isolated from the reaction of SiF 4 with the lithiated ketazine. 2-Alkenyl-1,2-diaza-3-sila-5-cyclopentenes, t-Bu(CH 2 )C- [N-SiR,R’-CH 2 -C(t-Bu)=N], (14 - 17) are obtained from the dilithiated ketazine and Hal 2 SiRR’. (14: Hal = Cl, R = Me, R’ = Ph; 15: Hal = F,R = t-Bu, R’ = Ph; 16: Hal = F,R = t-Bu, R’ = F; 17: Hal = F, R = N(t-Bu)SiMe 3 , R’ = F). X-ray structure analyses are presented for 7, 11, and 17.

Formation of the charge-transfer complexes between calix[4]crowns (1 - 4) and iodine in chloroform solution was studied using UV-vis spectrophotometry. The stability constants and the thermodynamic data of the resulting 1 : 1 complexes were determined and was found to decrease with increasing the size of the crown moiety of the calixcrown. All complexes formed were found to be enthalpy stabilized, and all except the complex of 2 were entropy destabilized.

A mixed-ligand orotato (HOr) complex of Cu(II) with 2,2’-bipyridine (bipy) was synthesized and characterized by elemental analysis, magnetic susceptibility, UV-vis and FT-IR spectroscopy, TG / DTA techniques and X-ray diffraction analysis. X-Ray diffraction analysis has shown that the squarepyramidal five-coordinate copper atom is chelated by the deprotonated N3 pyrimidine atom and the carboxylate oxygen atom of the bidentate orotato dianion, and to the two nitrogen atoms of the 2,2’- bipyridine molecule. A water molecule is attached above the N 3 O plane. Thermal analyses showed that the title compound decomposes in two steps over the range 20 - 1000 °C on heating in a static air atmosphere. Intermolecular hydrogen-bonds and π-ring interactions lead to the formation of a three-dimensional network.

9-Oxabicyclo[3.3.1]nona-2, 6-diene (3) has been synthesized from cycloocta-1, 5-diene in two steps in an overall yield of 88%. The dihedral-angle dependence of its 1 H solution NMR data and the double signal set of its 13 C CP MAS NMR spectrum correspond to the results of the single crystal structure analysis. Reaction of 3 with N-bromosuccinimide in the presence of sodium peroxodisulfate or benzoylperoxide has led in good yield to a dibromo derivative 4, and a tribromo derivative 5, respectively. Compounds 4 and 5 feature two allylic bromine substituents, while an additional vinylic bromine atom is present in 5. According to a single crystal structure study the lattice of 4 consists of pairs of enantiomers similar to those found in the case of 3.

Planar bis(1,2-dithiooxalato)nickelates(II) react in aqueous solutions of lanthanide ions to form pentanuclear, heterobimetallic complexes of the general composition [{Ln(H 2 O) n } 2 - {Ni(dto) 2 } 3 ]・xH 2 O (Ln = Y 3+ , La 3+ , Ce 3+ , Pr 3+ , Nd 3+ , Sm 3+ , Eu 3+ , Gd 3+ , Tb 3+ , Dy 3+ , Ho 3+ , Er 3+ , Tm 3+ , Yb 3+ , Lu 3+ ; n = 4 or 5; x = 9 - 12). With [{Nd(H 2 O) 5 } 2 {Ni(S 2 C 2 O 2 ) 2 } 3 ]・xH 2 O (x = 10 - 12) (1) and [{Er(H 2 O) 4 } 2 {Ni(S 2 C 2 O 2 ) 2 } 3 ]・xH 2 O (x = 9 - 10) (2) we were able to isolate two complexes of this series as single crystals, which were characterized by X-ray structure analysis. Depending on the individual ionic radii of the lanthanide ions, the compounds crystallize in two different crystal systems with the following unit cell parameters: 1, monoclinic in P2 1 /c with a = 11.3987(13), b = 11.4878(8), c = 20.823(2) Å , β = 98.907(9)° and Z = 2; 2, triclinic in P1̅ with a = 10.5091(6), b = 11.0604(6), c = 11.2823(6) Å , α = 107.899(4)°, β = 91.436(4)°, γ = 112.918(4)° and Z = 1. The channels and cavities appearing in the packing of the molecules are occupied by uncoordinated water molecules. High magnetic moments up to 14.65 BM./f.u. have been observed at room temperature due to the combined moments of the individual lanthanide ions.

Correlations between the photocatalytic and photoelectrocatalytic decolorization of methyl orange, using TiO 2 thin films sputtered under various conditions, were made. Three types of systems, namely: two photocatalytic systems, one with and one without a Pt counter electrode, and a third with a Pt counter electrode having an applied potential, were used to evaluate photocatalytic activity. The crystal structure, morphology, bandgap energy, flatband potential, and the resistances of the TiO 2 films were characterized by X-ray diffraction, scanning electron microscopy, UV/vis spectroscopy, a photocurrent method, and electrochemical impedance spectroscopy, respectively. The results showed that the decolorization of methyl orange only occurred on the anode of the TiO 2 /Ti electrode and that the decolorization rate increased 67% when the photocatalyst was coupled to a Pt electrode (0 V applied potential), and 275% when connected with the Pt cathode and 1 V vs. Ag/AgCl applied potential. The benefits of high crystallinity, a high quantity of the anatase, and a more negative flatband potential were found in the photocatalytic reaction, whereas the resistance of the film was the main factor affecting the photoelectrocatalytic activity.

2-Oxo-D-gluconic acid obtained by fermentation of D-glucose was used as starting material for syntheses of amino acids. We trapped the carbohydrate in its furanoid configuration and synthesized an α- and an ω-amino acid. After deprotection of the hydroxyl groups the latter did not isomerize to the substituted piperidine (aza-sugar) as expected, but remained in the furanose form. The starting structure 2 was proven by crystal structure analysis. The conformational identification of the other substances was done by NMR measurements following known rules for furanoses.

1-(Methyl 2-O-benzyl-4,6-O-benzylidene-3-deoxy-α-D-altropyranosid-3-yl)but-3-yn-2-one (3a) reacted with 3-amino-1H-1,2,4-triazole and 5-aminopyrazole-4-carboxylic acid derivatives in the presence of base to furnish the triazolo[1,5-a]pyrimidine (5) and the pyrazolo[1,5- a]pyrimidines (8a - d), respectively. Treatment of 1-(methyl 2-O-benzyl-4,6-O-benzylidene-3- deoxy-α-D-altropyranosid-3-yl)-4-phenyl-but-3-yn-2-one (3b) with cyanacetamide, 2-cyano-N- (4-methoxyphenyl)acetamide und N-aryl-3-oxo-butyramides afforded the substituted nicotinonitriles (11a - d). Furthermore, reaction of 3b with 2-benzimidazolyl-acetonitrile yielded the benz[4,5]imidazo[1,2-a]pyridine-4-carbonitrile (13). Deprotection of 8d in two steps afforded the 2-amino-N-benzyl-5-(methyl 3-deoxy-α-D-altropyranosid-3-yl-methyl)pyrazolo[1,5-a]pyrimidine- 3-carboxamide (10). Compounds 5 and 11d were treated with AcOH/H 2 O to furnish the 5-(methyl 2-O-benzyl-3-deoxy-α-D-altropyranosid-3-yl-methyl)[1,2,4]triazolo[1,5-a]pyrimidine (6) and the 3-acetyl-1,2-dihydro-1-(4-methoxyphenyl)-6-(methyl 2-O-benzyl-3-deoxy-α-D-altropyranosid-3-ylmethyl)- 4-phenylpyridin-2-one (12), respectively.

Aerial parts of Skimmia laureola yielded a new tyrosinase inhibitor fatty ester, (+)-skimmidiol (1), and a new alkaloid ribaliprenylene (2). The configuration at C-3’ in 1 was established by Horeau’s procedure. Compound 1 was screened for its enzyme inhibitory activity against tyrosinase (E.C.1.14.18.1), exhibiting activity with IC 50 51.25±1.10165 μ M .

Unsymmetrical oxalic acid-bis(imidoyl)dichlorides were prepared from ethyl 2-chloro-2-oxoacetate in three steps.

The supercritical fluid extraction (SFE) of clove bud essential oil was studied using CO 2 as solvent. The effect of operation conditions was analyzed in a series of experiments at temperatures between 325 and 416 K and pressures between 110 and 190 bar. The collected extracts were analyzed and the relative composition of the essential oil was determined. The optimum condition was found in a temperature of 353 K and at a pressure of 190 bar, minimizing the number of extracts to two compounds (eugenol and eugenyl acetate). The extract obtained from clove bud by using supercritical fluid extraction was compared with the essential oil obtained by steam distillation and microwave-assisted extraction by considering both quantity and quality of the product. The oil yield was higher in steam distillation and microwave oven extraction. In contrast, oil extracted by using SFE contained higher amount of eugenol and eugenyl acetate.

Studies on ommiphora mukul (Hook, ex stock) Engl. have led to the isolation of a new lignan (+)-commiphorin (1), a new fatty acid ester, (+)-commiphotetrol (2) along with (-)- hydroxyisohopane (3) [1], which is the first report of this compound from Commiphora mukul of Pakistan origin, Z and E-guggulsterones, cholesterol and guggulsterol-II (4). Of these complete 1 H and 13 C NMR data of guggulsterol-II (4) is assigned for the first time [2]. The structures of the compounds were elucidated with the help of extensive spectroscopic studies [3, 4]. Compound 1 have shown antibacterial activity against a number of bacteria. Amoxicillin (H 2 O) 3 , Ampicilin and Cefuroxime were used as positive control (Table 2).

N’,N’-Disubstituted (2-phenylamino)-, (2-methylamino)- and (2-benzylamino)benzohydrazides (1) are cyclized by in situ prepared 1,1’-oxalyldiimidazole to give 3-amino-2,3,4,5-tetrahydro-1H- 1,4-benzodiazepine-2,3,5-triones 2 as the major product. Depending on the substituents of 1 competitive formation of quinazoline-2,4-diones 3 and 1,3,4-oxadiazoline-2-one 4 is observed. The formation of heterocycles 2, 3, 4 is rationalized via a common primary intermediate 1A.

An HPTLC system commonly used for chromatographic separations and analytical quality control has been utilized non-chromatographically as a screening tool for antioxidant activity in the 2,2- diphenyl-1-picrylhydrazyl (DPPH) free-radical scavenging assay. The accurate and precise capabilities for sample application and densitometric analysis of dry spots were applied to determine the 50% inhibition of DPPH (IC 50 ) by a number of natural antioxidants at 530 nm. Concentration-response curves were generated from 3 rd degree polynomial fitting of data acquired for each antioxidant at 4 concentration levels. The IC 50 values ranged from 9.0 - 332.8 μ M with quercetin being the most active and silybin the least active of the pure compounds. Three antioxidant extracts were also evaluated and grapeseed extract was the most active (IC 50 8.3 μg/ml). The coefficients of variation for all IC 50 values were around 5% which indicated method reproducibility and the suitability of the used system for the intended purpose. Based on its densitometric evaluation of dry spots, the described technique provides an alternative to the spectrophotometric evaluation of samples in solution.