Cubic and ultimate groups of complete symmetry

It is shown that the systems of definite actions described by polar and axial tensors of the second rank and their combinations during the superposition of their elements of complete symmetry with the elements of complete symmetry of the "grey" cube, result in 11 cubic crystallographical groups of complete symmetry. There are 35 ultimate groups (i.e., the groups having the axes of symmetry of infinite order) in complete symmetry of finite figures. 14 out of these groups are ultimate groups of symmetry of polar and axial tensors of the second rank and 24 are new groups. All these 24 ultimate groups are conventional groups since they cannot be presented by certain finite figures possessing the axes of symmetry {Mathematical expression}. Geometrical interpretation for some of the groups of complete symmetry is given. The connection between complete symmetry and physical properties of the crystals (electrical, magnetic and optical) is shown.

Crystal structure of copper ammonium oxalate dihydrate, Cu(NH 4)2(C2O4)2.2H 2O

The crystal structure of copper ammonium oxalate dihydrate (space group P1̃) has been derived from a refinement of the two-dimensional (hk0) and (0kl) x-ray data using the atomic coordinateis of the isomorphous salt CuK 2(C2O4)2.2H2O as the starting point of the analysis. In contrast to the chromium complexes of oxalic acid the C-C bonds in both the two nonequivalent oxalate ions in the unit cell are single bonds (1.58 and 1.61 Å) consistent with the conclusion of Jeffrey and Parry that the carboxyl groups of the oxalate ion are separated by a pure a bond with little or no π conjugation across the molecule. Both the oxalate ions are slightly nonplanar. The copper ions occupy the special positions (0, 0, 0) and 0, 1/2, 0) and their coordination is of the distorted octahedral type with four nearest oxygen neighbors ( ≃ 2 Å) at the corners of a square and two more distant atoms along the octahedral bond direction. The environment of the NH4+ ions consists of eight nearest oxygen atoms at a mean distance of 3 Å.

1-[2,4,6-Trimethyl-3,5-bis(4-oxopiperidin ylmethyl) benzyl ]piperidin- 4-one

In the structure of the title compound, C27H39N3O3, each of the (4-oxopiperidin-1-yl)methyl residues adopts a flattened chair conformation (with the N and carbonyl groups being oriented to either,side of the central C-4 plane) and they occupy positions approximatelym orthogonal to the central benzene ring [C-benzene-C-C-methylene-N torsion angles 103.4 (2), -104.4 (3) and 71.9 (3)degrees]; further, two of these residues are oriented to one side of the central benzene ring with the third to the other side. In the crystal packing, supramolecular layers in the ab plane are sustained by C-H center dotcenter dot center dot O interactions.

X-ray Crystallographic Analysis of the Complexes of Enoyl Acyl Carrier Protein Reductase of Plasmodium falciparum with Triclosan Variants to Elucidate the Importance of Different Functional Groups in Enzyme Inhibition

Triclosan, a well-known inhibitor of Enoyl Acyl Carrier Protein Reductase (ENR) from several pathogenic organisms, is a promising lead compound to design effective drugs. We have solved the X-ray crystal structures of Plasmodium falciparum ENR in complex with triclosan variants having different substituted and unsubstituted groups at different key functional locations. The structures revealed that 4 and 2' substituted compounds have more interactions with the protein, cofactor, and solvents when compared with triclosan. New water molecules were found to interact with some of these inhibitors. Substitution at the 2' position of triclosan caused the relocation of a conserved water molecule, leading to an additional hydrogen bond with the inhibitor. This observation can help in conserved water-based inhibitor design. 2' and 4' unsubstituted compounds showed a movement away from the hydrophobic pocket to compensate for the interactions made by the halogen groups of triclosan. This compound also makes additional interactions with the protein and cofactor which compensate for the lost interactions due to the unsubstitution at 2' and 4'. In cell culture, this inhibitor shows less potency, which indicates that the chlorines at 2' and 4' positions increase the ability of the inhibitor to cross multilayered membranes. This knowledge helps us to modify the different functional groups of triclosan to get more potent inhibitors. (C) 2010 IUBMB IUBMB Life, 62(6): 467-476.

Synthesis and identification of a new class of (S)-2,6-diamino-4,5,6,7-tetrahydrobenzo[d]thiazole derivatives as potent antileukemic agents

Benzothiazoles are multitarget agents with broad spectrum of biological activity. Among the antitumor agents discovered in recent years, the identification of various 2-(4-aminophenyl) benzothiazoles as potent and selective antitumor drugs against different cancer cell lines has stimulated remarkable interest. Some of the benzothiazoles are known to induce cell cycle arrest, activation of caspases and interaction with DNA molecule. Based on these interesting properties of benzothiazoles and to obtain new biologically active agents, a series of novel 4,5,6,7-tetrahydrobenzo[d]thiazole derivatives 5(a-i) were synthesized and evaluated for their efficacy as antileukemic agents in human leukemia cells (K562 and Reh). The chemical structures of the synthesized compounds were confirmed by H-1 NMR, LCMS and IR analysis. The cytotoxicity of these compounds were determined using trypan blue exclusion, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays. Results showed that, these compounds mediate a significant cytotoxic response to cancer cell lines tested. We found that the compounds having electron withdrawing groups at different positions of the phenyl ring of the thiourea moiety displayed significant cytotoxic effect with IC50 value less than 60 mu M. To rationalize the role of electron withdrawing group in the induction of cytotoxicity, we have chosen molecule 5g (IC50 similar to 15 mu M) which is having chloro substitution at ortho and para positions. Flow cytometric analysis of annexin V-FITC/ propidium iodide (PI) double staining and DNA fragmentation suggest that 5g can induce apoptosis.

On the compactness of isometry groups in complex analysis

We prove that the group of continuous isometries for the Kobayashi or Caratheodory metrics of a strongly convex domain in C-n is compact unless the domain is biholomorphic to the ball. A key ingredient, proved using differential geometric ideas, is that a continuous isometry between a strongly convex domain and the ball has to be biholomorphic or anti-biholomorphic. Combining this with a metric version of Pinchuk's rescaling technique gives the main result.

Molecular and crystal structure of 4-ethynylcyanobenzene. An example of Csingle bondHcdots, three dots, centeredN hydrogen bonding

The molecular and crystal structures of 4-ethynylcyanobenzene arereported. The packing of molecules in the crystal is found to be homologous with the crystal structures of HCN, cyanoacetylene and 4-cyano-4'-ethynylbiphenyl. Alternatively, these four crystals could be said to constitute a structural homologous series. The influence of C-H center dot center dot center dot N hydrogen bonding in directing a linear supramolecular arrangement of molecules with ethynyl and cyano groups at opposite ends, is illustrated. (C) 2010 Elsevier B.V. All rights reserved.

Complexes of lanthanide nitrates with N,N-diethylantipyrine-4-carboxamide

New complexes of lanthanide nitrates with N, N-diethylantipyrine-4-carboxamide (DEAP), with the general formulae [Ln2(DEAP)3] [NO3]6 (where Ln = La, Pr, Nd, Sm, Tb, Ho, Er, Yb and Y) have been isolated and characterized by chemical analysis and various physical methods such as electrolytic conductance, IR and13C NMR spectral data. Electrolytic conductance values and infrared spectral studies indicate that the nitrate groups are coordinated. Infrared and13C NMR spectral analysis show that the ligand DEAP is coordinated to the tripositive metal ion through the diethylcarboxamide carbonyl and antipyrine carbonyl oxygens in a bidentate fashion.

Synthesis, crystal structures and magnetic behavior of two 3D coordination polymers using N-(4/3-arboxyphenyl)iminodiacetic acids as bridging ligands

Research on structure and magnetic properties of polynuclear metal complexes to understand the structural and chemical factors governing the electronic exchange coupling mediated by multi-atom bridging ligands is of growing interest. Hydrothermal treatment of Ni(NO3)(2)center dot 6H(2)O with N-(4-carboxyphenyl)iminodiacetic acid N-4(H(3)CPIDA)] at 150 degrees C yielded a 3D coordination polymer of general formula Ni-3{N-4( CPIDA)}(2)(H2O)(3)]center dot 6H(2)O (1). An analogous network of general formula Co-3{N-3(CPIDA)}(2)(H2O)(3)]center dot 3H(2)O (2) was synthesized using N-(3-carboxyphenyl) iminodiacetic acid N-3(H(3)CPIDA)] in combination with Co(NO3)(2)center dot 6H(2)O under identical reaction condition. Both the complexes contain trinuclear secondary building unit, and crystallized in monoclinic system with space groups C2/c (1) and P2(1)/c (2), respectively. Variable temperature magnetic characterization of these complexes in the temperature range of 2-300 K indicated the presence of overall ferromagnetic and antiferromagnetic behavior for 1 and 2, respectively. Density functional theory calculations (B3LYP functional) were performed for further insight on the trinuclear units to provide a qualitative theoretical interpretation on the overall magnetic behavior of the complexes 1 and 2. (C) 2010 Elsevier B.V. All rights reserved.

Non-enzymatic Degradation of (1→3)(1→4)-β-D-glucan in Aqueous Processing of Oats

Cereal water-soluble β-glucan [(1→3)(1→4)-β-D-glucan] has well-evidenced health benefits and it contributes to the texture properties of foods. These functions are characteristically dependent on the excellent viscosity forming ability of this cell wall polysaccharide. The viscosity is affected by the molar mass, solubility and conformation of β-glucan molecule, which are further known to be altered during food processing. This study focused on demonstrating the degradation of β-glucan in water solutions following the addition of ascorbic acid, during heat treatments or high pressure homogenisation. Furthermore, the motivation of this study was in the non-enzymatic degradation mechanisms, particularly in oxidative cleavage via hydroxyl radicals. The addition of ascorbic acid at food-related concentrations (2-50 mM), autoclaving (120°C) treatments, and high pressure homogenisation (300-1000 bar) considerably cleaved the β-glucan chains, determined as a steep decrease in the viscosity of β-glucan solutions and decrease in the molar mass of β-glucan. The cleavage was more intense in a solution of native β-glucan with co-extracted compounds than in a solution of highly purified β-glucan. Despite the clear and immediate process-related degradation, β-glucan was less sensitive to these treatments compared to other water-soluble polysaccharides previously reported in the literature. In particular, the highly purified β-glucan was relatively resistant to the autoclaving treatments without the addition of ferrous ions. The formation of highly oxidative free radicals was detected at the elevated temperatures, and the formation was considerably accelerated by added ferrous ions. Also ascorbic acid pronounced the formation of these oxidative radicals, and oxygen was simultaneously consumed by ascorbic acid addition and by heating the β-glucan solutions. These results demonstrated the occurrence of oxidative reactions, most likely the metal catalysed Fenton-like reactions, in the β-glucan solutions during these processes. Furthermore, oxidized functional groups (carbonyls) were formed along the β-glucan chain by the treatments, including high pressure homogenisation, evidencing the oxidation of β-glucan by these treatments. The degradative forces acting on the particles in the high pressure homogenisation are generally considered to be the mechanical shear, but as shown here, carbohydrates are also easily degraded during the process, and oxidation may have a role in the modification of polysaccharides by this technique. In the present study, oat β-glucan was demonstrated to be susceptible to degradation during aqueous processing by non-enzymatic degradation mechanisms. Oxidation was for the first time shown to be a highly relevant degradation mechanism of β-glucan in food processing.

Crystallographic identification of a ‘stepped-cubane’ structure for the Cu4O4 core in [Cu4L2(bipy)4(µ3-OH)2][ClO4]4(HL = 5-hydroxy-6-methylpyridine-,4-dimethanol, bipy = 2,2′-bipyridine)

The structure of [Cu4L2(bipy)4(µ3-OH)2][ClO4]4 containing a Vitamin B6 ligand, pyridoxine (5-hydroxy-6-methylpyridine-3,4-dimethanol, HL), and 2,2′-bipyridine (bipy) has been determined by single-crystal X-ray analysis. This is the first report on a copper(II) complex having a ‘stepped-cubane’ structure. The compound crystallizes in the triclinic space group P[1 with combining macron](Z= 1) with a= 11.015(3), b= 11.902(1), c= 13.142(2)Å, α= 105.07(1), β= 102.22(1) and γ= 99.12(1)°; R= 0.054). The co-ordination geometry around each copper is trigonally distorted square pyramidal. Two of the basal sites are occupied by bipyridyl nitrogens in a bidentate fashion. The remaining basal positions for Cu(1) are filled by a phenolic oxygen and a 4-hydroxymethyl oxygen of the L moiety, whereas for Cu(2) they are occupied by two µ3-OH oxygens. The axial sites are occupied by a µ3-OH oxygen and the 4-hydroxymethyl oxygen of the same pyridoxine for Cu(1) and Cu(2), respectively. Both the bridging nature of the 4-hydroxymethyl oxygen of the L moiety and the unsymmetrical bridging nature of the µ3-OH groups with axial–equatorial bridging are novel features. The structure is discussed in relation to stepped-cubane structures reported in the literature. A comparative study is also made with µ3-hydroxo-bridged copper(II) complexes. Both the plasticity effect of CuII and the stacking interactions between the various rings appear to be important in stabilizing this unusual structure.

Lanthanide perchlorate complexes of o,o' diisopropyl, n(-4-antipyryl) phosphoramidate

Five new complexes of lanthanide perchlorates with a new ligand O,O' diisopropyl N(-4-antipyryl) phosphoramidate (DIAP) of the general formula Ln(DIAP)4(ClO4)3 where Ln = La, Pr, Nd, Sm and Gd, have been synthesised and characterized by chemical analysis, IR(200–4000cm−1) and electronic spectra and electrical conductance data. Infrared spectral data indicate the coordination of the ligand to the metal ions in a bidentate fashion, through the C=O oxygen of the antipyrine group and the P=O group. IR and conductance values show that the three perchlorate groups are ionic. Electronic spectrum of the Nd3+ complex in the visible region, indicates reasonable covalency in the metal-ligand bond. The available data point to an eight coordinate geometry around the metal ions, with each ligand behaving in a bidentate ‘00’ fashion.

Insights into conformational and packing features in a series of aryl substituted ethyl-6-methyl-4-phenyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate

The supramolecular structures of eight aryl protected ethyl-6-methyl-4-phenyl-2-oxo-1,2,3,4-tetrahydropyrimidine- 5-carboxylates have been analyzed to determine the role of different functional groups on the molecular geometry, conformational characteristics and the packing of these molecules in the crystal lattice. Out of these the para fluoro substituted compound on the aryl ring exhibits conformational polymorphism, due to the different conformation of the ester moiety. This behaviour has been characterized using both powder and single-crystal X-ray diffraction, optical microscopy and differential scanning calorimetry performed on both these polymorphs. The compounds pack via the cooperative interplay of strong N-H center dot center dot center dot O=C intermolecular dimers and chains forming a sheet like structure. In addition, weak C-H center dot center dot center dot O=C and C-H center dot center dot center dot pi interactions impart additional stability to the crystal packing.

Social selection and the evolution of cooperative groups: The example of the cellular slime moulds

In social selection the phenotype of an individual depends on its own genotype as well as on the phenotypes, and so genotypes, of other individuals. This makes it impossible to associate an invariant phenotype with a genotype: the social context is crucial. Descriptions of metazoan development, which often is viewed as the acme of cooperative social behaviour, ignore or downplay this fact. The implicit justification for doing so is based on a group-selectionist point of view. Namely, embryos are clones, therefore all cells have the same evolutionary interest, and the visible differences between cells result from a common strategy. The reasoning is flawed, because phenotypic heterogeneity within groups can result from contingent choices made by cells from a flexible repertoire as in multicellular development. What makes that possible is phenotypic plasticity, namely the ability of a genotype to exhibit different phenotypes. However, co-operative social behaviour with division of labour requires that different phenotypes interact appropriately, not that they belong to the same genotype, or have overlapping genetic interests. We sketch a possible route to the evolution of social groups that involves many steps: (a) individuals that happen to be in spatial proximity benefit simply by virtue of their number; (b) traits that are already present act as preadaptations and improve the efficiency of the group; and (c) new adaptations evolve under selection in the social context-that is, via interactions between individuals-and further strengthen group behaviour. The Dictyostelid or cellular slime mould amoebae (CSMs) become multicellular in an unusual way, by the aggregation of free-living cells. In nature the resulting group can be genetically homogeneous (clonal) or heterogeneous (polyclonal); in either case its development, which displays strong cooperation between cells (to the extent of so-called altruism) is not affected. This makes the CSMs exemplars for the study of social behaviour.