Reaction-path calculations and crystal structures of 1,1'-(ethylene-1,2-diyl)dipyridinium dichloride dihydrate and 1,1'-(ethylene-1,2-diyl)dipyridinium dibromide.

The design of new organic-inorganic hybrid ionic materials is of interest for various applications, particularly in the areas of crystal engineering, supramolecular chemistry and materials science. The monohalogenated intermediates 1-(2-chloroethyl)pyridinium chloride, C5H5NCH2CH2Cl(+)·Cl(-), (I'), and 1-(2-bromoethyl)pyridinium bromide, C5H5NCH2CH2Br(+)·Br(-), (II'), and the ionic disubstituted products 1,1'-(ethylene-1,2-diyl)dipyridinium dichloride dihydrate, C12H14N2(2+)·2Cl(-)·2H2O, (I), and 1,1'-(ethylene-1,2-diyl)dipyridinium dibromide, C12H14N2(2+)·2Br(-), (II), have been isolated as powders from the reactions of pyridine with the appropriate 1,2-dihaloethanes. The monohalogenated intermediates (I') and (II') were characterized by multinuclear NMR spectroscopy, while (I) and (II) were structurally characterized using powder X-ray diffraction. Both (I) and (II) crystallize with half the empirical formula in the asymmetric unit in the triclinic space group P-1. The organic 1,1'-(ethylene-1,2-diyl)dipyridinium dications, which display approximate C2h symmetry in both structures, are situated on inversion centres. The components in (I) are linked via intermolecular O-H...Cl, C-H...Cl and C-H...O hydrogen bonds into a three-dimensional framework, while for (II), they are connected via weak intermolecular C-H...Br hydrogen bonds into one-dimensional chains in the [110] direction. The nucleophilic substitution reactions of 1,2-dichloroethane and 1,2-dibromoethane with pyridine have been investigated by ab initio quantum chemical calculations using the 6-31G** basis. In both cases, the reactions occur in two exothermic stages involving consecutive SN2 nucleophilic substitutions. The isolation of the monosubstituted intermediate in each case is strong evidence that the second step is not fast relative to the first.

Saccharomyces cerevisiae SHSY detoxifies petroleum n-alkanes by an induced CYP52A58 and an enhanced order in cell surface hydrophobicity.

Environmental hydrocarbon contamination has a serious hazard to human health. Alkanes, the major component of hydrocarbons, can be consumed by various species of yeast. We previously identified a new strain SHSY of Saccharomyces cerevisiae with a remarkable ability to utilize the petroleum crude-oil (PCO) in aqueous solution. The current study demonstrated that the n-alkanes-assimilation activity of S. cerevisiae SHSY was related to an induced microsomal protein of 59 kDa approximately. The identified ORF encoded a protein of 517 amino acids and shared 93% sequence identity with an alkane-inducible hydroxylase CYP52A53 isolated from Scheffersomyces stipitis CBS. It was therefore referred as CYP52A58. The catalytic activity of the recombinant CYP52A58 was confirmed by the hydroxylation of n-alkanes, it showed an optimal mono-terminal hydroxylation activity toward n-hexadecane. Moreover, the ability of the yeast to use n-alkanes was accompanied with an increasing level in cell wall mannoproteins. Two differential protein bands were detected in the mannoproteins extracted from PCO-grown yeast. In parallel, a significant increase in the fatty acids content with a high degree of unsaturation was subsequently detected in the PCO-grown yeast. This study characterizes a safe and potential microorganism to remove n-alkanes from the aquatic environment.

Algal sulfated carrageenan inhibits proliferation of MDA-MB-231 cells via apoptosis regulatory genes.

Marine algae are prolific sources of sulfated polysaccharides, which may explain the low incidence of certain cancers in countries that traditionally consume marine food. Breast cancer is one of the most common types of non­skin cancer in females. In this study, extracted sulfated carrageenan (ESC), predominantly consisting of ι­carrageenan extracted from the red alga Laurencia papillosa, was characterized using Fourier transform infrared spectrometry. The biological effects of the identified extract were investigated and its potential cytotoxic activity was tested against the MDA­MB­231 cancer cell line. The biological biometer of the inhibitory concentration of the polysaccharide­treated MDA­MB­231 cells was determined as 50 µM. Treatment with 50 µM ESC inhibited cell proliferation and promptly induced cell death through nuclear condensation and DNA fragmentation. Characterization of polysaccharide­treated MDA­MB­231 cell death revealed that induction of apoptosis occurred via the activation of the extrinsic apoptotic caspase­8 gene. The apoptotic signaling pathway was regulated through caspase­3, caspase­9, p53, Bax and Bcl­2 genes. These findings suggest that ESC may serve as a potential therapeutic agent to target breast cancer via prompting apoptosis.

Powder X-ray investigation of 4,4'-diisocyano-3,3'-dimethyl-biphen-yl.

The title compound, C16H12N2, was investigated in a powder diffraction study and its structure refined utilizing the Rietveld Method. The mol-ecule has approximate C2 symmetry. The dihedral angle between the rings is 25.6 (7)°. The crystal packing is consolidated by weak C-H⋯C N hydrogen-bond-like contacts, which lead to the formation of a three-dimensional network. Further stabilization of the crystal structure is achived by weak non-covalent π-π inter-actions between aromatic rings, with a centroid-centroid distance of 3.839 (8) Å.

1,1'-Methylenedipyridinium tetrachloridocuprate(II) and bis[tetrachloridoaurate(III)] hybrid salts by X-ray powder diffraction.

In order to explore the potential propensity of the 1,1'-methylenedipyridinium dication to form organic-inorganic hybrid ionic compounds by reaction with the appropriate halide metal salt, the organic-inorganic hybrid salts 1,1'-methylenedipyridinium tetrachloridocuprate(II), (C(11)H(12)N(2))[CuCl(4)], (I), and 1,1'-methylenedipyridinium bis[tetrachloridoaurate(III)], (C(11)H(12)N(2))[AuCl(4)](2), (II), were obtained by treatment of 1,1'-methylenedipyridinium dichloride with CuCl(2) and Na[AuCl(4)], respectively. Both hybrid salts were isolated as pure compounds, fully characterized by multinuclear NMR spectroscopy and their molecular structures confirmed by powder X-ray diffraction studies. The crystal structures consist of discrete 1,1'-methylenedipyridinium dications and [CuCl(4)](2-) and [AuCl(4)](-) anions for (I) and (II), respectively. As expected, the dications form a butterfly shape; the Cu(II) centre of [CuCl(4)](2-) has a distorted tetrahedral configuration and the Au(III) centre of [AuCl(4)](-) shows a square-planar coordination. The ionic species of (I) and the dication of (II) each have twofold axial symmetry, while the two [AuCl(4)](-) anions are located on a mirror-plane site. Both crystal structures are stabilized by intermolecular C-H···Cl hydrogen bonds and also by Cl···π interactions. It is noteworthy that, while the average intermolecular centroid-centroid pyridinium ring distance in (I) is 3.643 (8) Å, giving strong evidence for noncovalent π-π ring interactions, for (II), the shortest centroid-centroid distance between pyridinium rings of 5.502 (9) Å is too long for any significant π-π ring interactions, which might be due to the bulk of the two [AuCl(4)](-) anions.

2-(Benzoylsulfanyl)acetic acid and 2,5-dioxopyrrolidin-1-yl 2-(benzoylsulfanyl)acetate by powder X-ray diffraction studies.

The structures of the title compounds, C(9)H(8)O(3)S, (I), and C(13)H(11)NO(5)S, (II), were determined by X-ray powder diffraction. Both were solved using the direct-space parallel tempering algorithm and refined using the Rietveld method. In (I), the C-S-C bond angle is slightly smaller than normal, indicating more p character in the bonding orbitals of the S atom. The carboxylic acid group joins across an inversion centre to form a dimer. The crystal packing includes a weak C-H···O hydrogen bond between an aromatic C-H group and a carboxylic acid O atom to form a two-dimensional network parallel to (10 ̅1). The C-S-C bond angle in (II) is larger than its counterpart in (I), indicating that the S atom of (II) has less p character in its bonding orbitals than that of (I), according to Bent's rule. The crystal structure of (II) includes weak C-H···O hydrogen bonds between the H atoms of the methylene groups and carbonyl O atoms, forming a three-dimensional network.

Powder X-ray studies of meso-hexamethyl propylene amine oxime (meso-HMPAO) in two different phases.

Two different forms of meso-3,3'-[2,2-dimethylpropane-1,3-diylbis(azanediyl)]dibutan-2-one dioxime, commonly called meso-hexamethyl propylene amine oxime (HMPAO), C(13)H(28)N(4)O(2), designated alpha and beta, were isolated by fractional crystallization and their crystal structures were determined by powder X-ray diffraction using the direct-space method with the parallel tempering algorithm. The alpha form was first crystallized from acetonitrile solution, while the beta form was obtained by recrystallization of the alpha phase from diethyl ether. The alpha form crystallizes in the triclinic system (space group P-1), with one molecule in the asymmetric unit, while the crystal of the beta form is monoclinic (space group P2(1)/n), with one molecule in the asymmetric unit. In both phases, the molecules have similar conformations and RS/EE geometric isomerism. The crystal packing of the two phases is dominated by intermolecular hydrogen-bonding interactions between the two O-H oxime groups of an individual molecule and the amine N atoms of two different adjacent molecules, which lead to segregation of extended poly(meso-HMPAO) one-dimensional chains along the c direction. The structures of the two phases are primarily different due to the different orientations of the molecules in the chains.

Poly[µ-bromido-µ-(2,2-dimethyl-propane-1,3-diyl diisocyanide)-silver(I)]: a powder diffraction study.

In the title compound, [AgBr(C(7)H(10)N(2))](n), adjacent Ag(I) atoms are bridged by bidentate CNCH(2)C(CH(3))(2)CH(2)NC ligands via the NC groups, forming [Ag{CNCH(2)C(CH(3))(2)CH(2)NC}](n) chains with the metal atom in a distorted tetrahedral coordination. The bromide counter-anions cross-link the Ag(I) atoms of the chains, forming a two-dimensional polymeric network {[Ag(I)(CNCH(2)C(CH(3))(2)CH(2)NC)]Br}(n) extend-ing parallel to (010). The polymeric structure is similar to that of the very recently reported Cl(-), I(-) and NO(3) (-) analogues. This gives a strong indication that 2,2-dimethyl-propane-1,3-diyl diisocyanide is a potential ligand for giving polymeric structures on treatment with AgX (X = Cl(-), Br(-), I(-) or NO(3) (-)) regardless of the counter-anion used.

Powder study of poly[(mu(2)-2,2-dimethylpropane-1,3-diyl diisocyanide)-mu(2)-iodido-silver(I)].

In order to explore the chemistry of the bidentate ligand 2,2-dimethylpropane-1,3-diyl diisocyanide and to investigate the effect of counter-ions on the polymeric structure of (2,2-dimethylpropane-1,3-diyl diisocyanide)silver(I) complexes, the title polymeric compound, [AgI(C(7)H(10)N(2))](n), was synthesized by treatment of 2,2-dimethylpropane-1,3-diyl diisocyanide with AgI. X-ray powder diffraction studies show, as expected, a polymeric structure, similar to the very recently reported Cl(-) and NO(3)(-) analogues [AgX(C(7)H(10)N(2))](n) (X = Cl(-) or NO(3)(-)). In the title structure, the Ag(I) centre is bridged to two adjacent Ag(I) neighbours by bidentate 2,2-dimethylpropane-1,3-diyl diisocyanide ligands via the NC groups to form [Ag{CNCH(2)C(CH(3))(2)CH(2)NC}](n) chains. The iodide counter-ions crosslink the Ag(I) centres of the chains to form a two-dimensional polymeric {[Ag{CNCH(2)C(CH(3))(2)CH(2)NC}]I}(n) network. This study also shows that this bidentate ligand forms similar polymeric structures on treatment with AgX, regardless of the nature of the counter-ion X(-), and also has a strong tendency to form polymeric complexes rather than dimeric or trimeric ones.

Specific insertion reactions of a germylene, stannylene and plumbylene into the unique P-P bond of the hexaphospha-pentaprismane cage, P6C4tBu4: crystal and molecular structures of P6C4tBu4ER2 (E = Ge, Sn, R = N(SiMe3)2; E = Pb, R = (C6H3(NMe2)2 -2,6).

Treatment of the cage compound P6C4(t)Bu4 with M(N(SiMe3)2)2 (M = Ge or Sn) or Pb(C6H3(NMe2)2- 2,6) at room temperature results in their specific insertion into the P-P bond connecting the two 5-membered P3C2(t)Bu2 rings. The products were fully characterised by multinuclear NMR spectroscopy and single crystal X-ray diffraction studies.

Poly[(mu2-2,2-dimethylpropane-1,3-diyl diisocyanide)-mu2-nitrato-silver(I)]: a powder study.

In order to investigate the effect of counter-anions on the polymeric structure of (2,2-dimethylpropane-1,3-diyl diisocyanide)silver(I) complexes, the novel title polymeric compound, [Ag(NO(3))(C(7)H(10)N(2))](n), has been synthesized. The crystal structure was determined by simulated annealing from X-ray powder diffraction data collected at room temperature. The current structure is similar to the recently reported structure of the analogue with chloride replacing nitrate. This study illustrates that both the chloride and nitrate complexes crystallize in the orthorhombic system in the Pbca space group with one monomer in the asymmetric unit, and also gives a strong indication that the counter-anion does not have a considerable effect on the polymeric structure of the complex. The Ag centre lies in a distorted tetrahedral environment and is bonded to two 2,2-dimethylpropane-1,3-diyl diisocyanide ligands to form chains. The nitrate anions crosslink the Ag centres of the chains to form a two-dimensional polymeric network structure.

Facile insertion and halogen migration reactions of the hexaphosphapentaprismane cage P6C4tBu4 with zerovalent and divalent platinum complexes.

The hexaphosphapentaprismane P(6)C(4)(t)Bu(4) undergoes specific insertion of the zerovalent platinum fragment [Pt(PPh(3))(2)] into the unique P-P bond between the 5-membered rings to afford [Pt(PPh(3))(2)P(6)C(4)(t)Bu(4)]. A similar reaction with the Pt(ii) complexes [{PtCl(2)(PMe(3))}(2)] and [PtCl(2)(eta(4)-COD)] results in both insertion and chlorine migration reactions. The complexes [Pt(PPh(3))(2)P(6)C(4)(t)Bu(4)], trans-[PtCl(PMe(3))P(6)C(4)(t)Bu(4)Cl], cis-,trans-[{PtCl(2)(PMe(3))}micro-{P(6)C(4)(t)Bu(4)}{PtCl(2)(PMe(3))}], [{PtClP(6)C(4)(t)Bu(4)Cl}(2)] and cis-[PtClP(6)C(4)(t)Bu(4)Cl(P(6)C(4)(t)Bu(4))] have been structurally characterized by single crystal X-ray diffraction and multinuclear NMR studies.

Hexaphosphapentaprismane: a new gateway to organophosphorus cage compound chemistry.

Several independent synthetic routes are described leading to the formation of a novel unsaturated tetracyclic phosphorus carbon cage compound tBu4C4P6 (1), which undergoes a light-induced valence isomerization to produce the first hexaphosphapentaprismane cage tBu4C4P6 (2). A second unsaturated isomer tBu4C4P6 (9) of 1 and the bis-[W(CO)5] complex 13 of 1 are stable towards similar isomerization reactions. Another starting material for the synthesis of the hexaphosphapentaprismane cage tBu4C4P6 (2) is the trimeric mercury complex [(tBu4C4P6)Hg]3 (11), which undergoes elimination of mercury to afford the title compound 2. Single-crystal X-ray structural determinations have been carried out on compounds 1, 2, 9, 11, and 13.