Volume 63, Issue 11

Two new thiostannates with Mn 2+ ions were obtained under solvothermal conditions applying different amine concentrations. [Mn(C 6 H 14 N 2 ) 2 (H 2 O)] 2 Sn 2 S 6 (1) (C 6 H 14 N 2 = 1,2-diaminocyclohexane, 1,2-dach) crystallizes in the monoclinic space group C2/c (with a = 23.7500(18), b = 15.5655(16), c = 12.1072(9) Å , β = 113.532(8)°, Z = 8). The second compound, [Mn(C 6 H 14 N 2 )2]- Sn2S6 ・2 C6H15N2 (2), crystallizes in the triclinic space group P¯1 with a = 7.3019(6), b = 11.1798(9), c = 13.2837(11) Å , α = 76.877(10), β = 74.719(9), γ = 82.972(10)°, Z = 1. Both structures feature [Sn 2 S 6 ] 4− anions acting as bidentate ligands and joining the octahedrally coordinated Mn2+ cations, but in 1 a molecular complex is formed, whereas in 2 a one-dimensional coordination polymer is observed. In 1 the Mn 2+ cation has bonds to four N atoms of two 1,2-dach ligands, to one H 2 O molecule, and to one S atom of the [Sn 2 S 6 ] 4− anion. The [Sn 2 S 6 ] 4− anion is located on a center of inversion joining two symmetry related complexes. In 2 Mn 2+ is surrounded by four N atoms of two 1,2-dach ligands and by two S atoms of two neighboring [Sn 2 S 6 ] 4− anions. In contrast to 1 a negatively charged coordination polymer is formed with [Sn 2 S 6 ] 4− anions acting as linkers and the Mn 2+ centered complexes being the nodes. The co-crystallized 1,2-dach molecules are protonated, and they are located between the chains. The first compound was obtained from diluted aqueous solutions of 1,2-dach, and 2 crystallized from solutions containing < 25% H 2 O. In both compounds several short S···H distances indicate weak hydrogen bonding interactions. Compound 1 is stable up to 121 °C and 2 up to 220 °C. In the Raman spectra of 1 and 2 resonances which are typical for [Sn 2 S 6 ] 4− units could be observed. The band gaps are found to be 2.6 eV (477 nm) and 3.1 eV (400 nm) for 1 and 2, respectively.

The reactions of unprotected D-glucosamine with N-coordinated, activated amino acid ester ligands (glycine, diglycine, histidine) of platinum(II) and palladium(II) complexes afford cis- and trans- Cl 2 Pt(NH 2 CH 2 CONHR), trans-Cl 2 Pt(NH 2 CH 2 CONHCH 2 CONHR) 2 and Cl 2 Pd(histNHR) 2 (R = sugar residue) as products. 1,2-Diaminocyclohexane reacts with the activated esters of cis-Cl 2 Pt- (NH 2 CH 2 COOH) 2 , cis-Cl 2 Pt(triglyOH) 2 , cis-Cl 2 Pt(metOH) and cis-Cl 2 Pd(histOH) to give dinuclear complexes Cl 2 Pt[(gly)nNHC 6 H 10 NH(gly)n] 2 PtCl 2 (n = 1, 3), Cl 2 Pt(methNHC 6 H 10 NHmeth)- PtCl 2 and Cl 2 Pd(histNHC 6 H 10 NHhist)PdCl 2 .

The title complex [Fe(C 8 H 10 N 5 S) 2 ] · Cl has been synthesized from 2-acetylpyrazine N(4)-methylthiosemicarbazone and FeCl 3 · 6H 2 O and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. The complex consists of discrete monomeric molecules with octahedrally hexacoordinated iron(III) ions, in which two 2-acetylpyrazine 4-methylthiosemicarbazone units act as meridional NNS tridentate ligands coordinated to the central iron atom via the pyrazine nitrogen, azomethine nitrogen and sulfur atoms. Hydrogen bonds link the complex components to stabilize the crystal structure. The antitumor activity of the title complex was tested against K562 leucocythemia and BEL7402 liver cancer cell lines. The complex exhibits higher antitumor activity as compared to the free ligand.

The complexes [Zn(dpa)MoO 4 ] (1) and [Zn(dpa)MoO 4 ]·0.5H 2 O (20.5H 2 O) (dpa = 2,2'-dipyrid- ylamine) were synthesized hydrothermally. Single crystal structure analyses indicate that 1 and 2 are conformational isomers. They both consist of binuclear units of edge-sharing {ZnN 2 O 3 } trigonal bipyramids bridged by pairs of bidentate briding {MoO 4 } 2- anions into a one-dimensional ribbon, but their orientations of the terminal O atoms of the {MoO 4 } 2- anions are different. In 1 and 2, the ribbon-like chains are connected into a 2D network via hydrogen bonding interactions between the central N-H portions of the dpa molecules and the terminal O atoms of {MoO 4 } tetrahedra. For 2, in addition, the hydrogen bonding interactions between the crystal water molecules and the terminal O atoms of {MoO 4 } tetrahedra join the 2D layers into a 3D architecture. They play an important role not only in constructing the 3D architecture, but also in the conformational stability.

Triethylborane, BEt 3 , can act as a 1,2-hydroborating reagent towards alkyn-1-ylsilanes, depending on the nature of the silane. A mechanism is proposed invoking hydrogen transfer from the β -carbon of one ethyl group, quite different from the 1,2-hydroboration mechanism using tri-n-propylborane, B n Pr 3 . The structure of the products has been confirmed by comparison with that obtained using 9-borabicyclo[3.3.1]nonane, 9-BBN, as a well established 1,2-hydroborating reagent. All products have been characterized by a consistent set of NMR data ( 1 H, 11 B, 13 C and 29 Si NMR). The molecular structure of (Z)-1-dichlorosilyl-1-[9-(9-borabicyclo[3.3.1]nonyl)]-2-phenylethene has been determined by single crystal X-ray diffraction.

Cocrystallization of tetramethylurea (TMU) with one equivalent of either di(4-fluorobenzenesulfo- nyl)amine (FAH), di(4-chlorobenzenesulfonyl)amine (CAH), di(4-bromobenzenesulfonyl)amine (BAH). di(4-iodobenzenesulfonyl)amine (IAH), di(4-methylbenzenesulfonyl)aniine (MAH>, ordi(4- nitrobenzenesulfonyDamine (NAH), using dichloromethane/petroleum ether as the solvent, afforded the molecular complexes (FAH) 2 · TMU (1. monoclinic. P2 1 /c,Z' = 1. structure previously reported), CAHTMU, BAH-TMU and IAH-TMU (2-4, isomorphic series, triclinic, P1̅,Z' = 1), MAH · TMU (5, monoclinic. P2 1 , Z' = 1). and the uranium salt TMUH + NA - (6, monoclinic. P2 1 /c,Z' = 2). The structural results obtained by X-ray crystallography at low temperatures indicate that the varying p- substituents of the di(arenesulfonyl)amines exert a decisive influence on (i) the stoichiometry of the cocrystallization reaction (2:1 for 1 vs. 1:1 for 2-6), (ii) the degree of proton transfer between the strongly acidic (SO 2 ) 2 NH moieties and the basic carbonyl function of TMU (molecular complexes assembled via N-H···O=C hydrogen bonds in 1 -5 vs. two independent ion pairs based upon charge- assisted C-O-H + ···N - interactions in 6). and (Hi) the conformation of the disulfonylamineZ-amide units as defined by rotations about the S-N bonds (extended forms displaying anticlinal C-S ··· S'- C' torsions for the two molecules in 1 and the two anions in 6 vs. folded forms featuring synperi- planar C-S ···S'-C torsions for the molecules in 2-5). The packing modes of 1-4 underline the well-known correlation between the atomic number of halogen atoms and their propensity to form halogen bonds. Thus, the structure of 1 is devoid of short F···O contacts, whereas the isomorphic co- crystals 2-4 consist of lamellar layers in which the inner lamellae include the TMU molecules and the peripheral regions are built up from CAH, BAH or IAH molecules associated into catemers via C-Hal ··· O=S bonds. The lamellar layers of the non-isomorphic methyl congener 5. although topological^' similar to those of 2-4, are stacked according to a herringbone pattern that does not arise in the structures of 2-4. The most prominent packing feature of the uranium salt 6 are intimate dimers of two independent NA - ions, stabilized by dipolar nitro-nitro interactions and C-H ··· O=S contacts and further connected into monolayers through C-H ··· O nitro contacts. The uranium ions are inserted between these layers and bonded to the anion dimers by the strong hydrogen bonds mentioned above and numerous C-H ··· O nitro contacts. The presence of two independent formula units appears to arise from frustration between several competing interactions, e. g. dipolar nitro attractions, weak hydrogen bonding to sulfonyl and nitro acceptors and π/π stacking of aromatic rings.

The preparative electroreduction of the three methyl monochlorobenzoates, the six methyl dichlorobenzoates, and methyl 2,3,4-trichlorobenzoate in different solvent-supporting electrolytes (SSE) was studied. The rate of the dechlorination, which is the main reaction, is dependent on the substitution pattern. Pronounced regioselectivity is therefore observed in case of the oligochloro derivatives. Hydrogenation of the benzene ring and reduction of the methoxycarbonyl group with formation of a hydroxymethyl group are observed as side-reactions. Quantum chemical calculations on the reaction mechanism were performed. The theoretical results are in accordance with the experimental observations.

A simple synthesis, involving a key coupling reaction, and the biological activity of the title compounds 16 and 17 are described. The key fragments are the amine·HCl salt 6 and the acids 9 and 13, which were smoothly coupled by using ethyl(dimethylaminopropyl)carbodiimide (EDCI) and 1- hydroxybenzotriazole (HOBt) in high yield.We have found that the in vitro growth inhibitory potency of the new compounds 16 and 17 exhibits good histone deacetylase (HDAC) activity.

4-Amino-3-p-methoxybenzyl-5-oxo-4,5-dihydro-1,2,4-triazol-1-yl-acetic acid ethyl ester (2) was prepared from 4-amino-4,5-dihydro-1H-1,2,4-triazole-5-one (1) and ethyl bromoacetate. Compound 3 was synthesized by the condensation of 2 with hydrazine hydrate. The treatment of compound 3 with various aromatic aldehydes resulted in the formation of arylidene hydrazides as cistrans conformers 4a - g. Thiosemicarbazide derivative 5 was prepared by the reaction of compound 3 with phenylisothiocyanate. Cyclization of 5 with sodium hydroxide resulted in the formation of compound 6. Treatment of 6 with benzyl bromide gave compound 7. Four of the newly synthesized compounds were screened for their anticancer activity against a panel of 60 cell lines derived from nine cancer types, namely, non-small cell lung, colon, breast, ovarian, leukemia, renal, melanoma, prostate and CNS cancers at a fixed dose of 10 μM.

N-(2-hydroxy-4-methoxybenzylidene)-3-nitroaniline (1) has been synthesized and characterized by X-ray diffraction analysis, FTIR and 1 H NMR spectroscopy. The maximum one-photon absorption (OPA) wavelengths recorded by quantum mechanical computations using a configuration interaction (CI) method are estimated in the UV region to be shorter than 450 nm, showing good optical transparency to the visible light. We have computed both dispersion-free (static) and also frequency-dependent (dynamic) linear polarizabilities (α) and second hyperpolarizabilities (γ) by using the time-dependent Hartree-Fock (TDHF) method to provide an insight into the microscopic third-order nonlinear optical (NLO) behavior of the title compound. The ab initio calculation results with non-zero values on (hyper)polarizabilities indicate that the synthesized molecule might possess microscopic third-order NLO phenomena.

The photophysics of Ochratoxin A (OTA) in aqueous solution strongly depends on the pH. Due to its molecular structure OTA is prone to an excited state proton transfer reaction, which rules the photophysical properties. Based on results of absorption and fluorescence measurements the rate constants of the proton transfer reactions (forward and back reaction) were determined and subsequently, the pK * a value was calculated. Based on the results, optimized experimental conditions for the analysis can be determined e. solvent conditions (HPLC chromatography) or excitation and emission wavelength (fluorescence spectroscopy).

A reliable screen-printing technique for fabricating an Ag/AgCl reference electrode on a solid substrate in a simple two-step procedure, which allows the incorporation of four different ion-selective electrodes on a chip, is presented. A ‘sandwich’ composite structure, comprising the reference electrode and a chip, was fabricated as a junction polymer membrane having an inner electrolyte layer and an Ag/AgCl electrode supported on a ceramic substrate. The junction polymer membrane was composed of chloroprene rubber, and the electrolyte layer was formed from agar gel. The electrochemical characteristics and performance of the reference electrode when integrated into a chip were investigated. From the results, it was shown that the potential change at the reference electrode chip as a function of the chloride ion concentration and pH can be kept reliably small. Its potential was also independent of the presence of other, physiologically significant, ions such as Ca 2+ , K + and Li + . The reference electrode, fabricated as a chip, can be used continuously for more than 60 h. Furthermore, its integration with four different ion-selective electrodes (potassium, sodium, ammonium, and calcium) on a substrate to form an ion sensor array chip was shown to be a facile process. The integration procedures and the sensing performances of the ion sensor array chip are also described.

Two new pentacyclic triterpenes 8,26-cyclo-urs-21-en-3β, 20β-diol (1) and 3β-acetoxy-8.26- cyclo-ursan-20β-ol (2) together with 3-friedelanone, oleanolic acid, betulinic acid, lupeol acetate, α- and β-amyrine, S.SJ^'-tetrahydroxyflavane, and 3,5,7,3',4'-pentahydroxyflavane were isolated from the stem bark of Ficus cordata (Moraceae). The structures of these secondary metabolites were established using ID and 2D NMR spectra and by comparison with published data or with authentic samples. Compounds 1 and 2 exhibited weak antibacterial and no antifungal activity.

Utilizing unsymmetrical 1,2,4-benzenetricarboxylate (1,2,4-BTC) as a ligand, a complex [Mn 2.5 (1,2,4-BTC)- (OH) 2 (H 2 O)] was synthesized by hydrothermal reaction and characterized by single crystal X-ray diffraction. The coordination polymer crystallizes in the triclinic space group P1̅, with cell parameters a = 5.7702(5), b = 8.0269(6), c = 12.1378(9) Å, α = 88.000(1)°, β = 81.493(1)◦, γ = 88.569(1)°, and Z = 2. In the the crystal, there are Mn- O-Mn sheets which are further connected through the 1,2,4-BTC ligands into a 3D framework, which is rare in the coordination chemistry originating from transition metal ions and unsymmetrical polycarboxylates.

A novel 1D zinc(II) coordination polymer [Zn(absa)- (pcih)](CH 3 OH) (1) (Habsa = 4-aminobenzenesulfonic acid, Hpcih = 2-pyridinecarbaldehyde isonicotinoylhydrazone) has been synthesized by solvothermal reaction at 72 °C and structurally characterized. Each Zn 2+ ion is five-coordinated by three N atoms and one O atom from two pcih ligands, and one O atom of an absa ligand, forming a distorted squarepyramidal geometry. Zn 2+ ions are bridged by pcih ligands in a zig-zag arrangement generating infinite chains with appended absa ligands. Photoluminescent studies have shown that 1 exhibits an emission at 535 nm (λ ex = 492 nm).