Quantitative measure of structural and geometric similarity of 3D morphologies

This work describes a new heuristic algorithm that estimates structural and geometric similarity of three‐dimensional morphologies. It is an extension to previously developed measure of similarity (Komosinski et al., Theor Biosci 2001, 120, 271–286) that was only able to consider the structure of 3D constructs. Morphologies are modeled as graphs with vertices as points in a 3D space, and edges connecting these vertices. This model is very general, therefore the proposed algorithm can be applied in (and across) a number of disciplines including artificial life, evolutionary design, engineering, robotics, biology, and chemistry. The primary areas of application of this fast numerical similarity measure are artificial life and evolutionary design, where great numbers of morphologies result from simulated evolutionary processes, and both structural and geometric aspects are significant. Geometry of 3D constructs (i.e., locations of body parts in space) is as important as the structure (i.e., connections of body parts), because both determine behavior of creatures or designs and their fitness in a particular environment. In this work, both morphological aspects are incorporated in a single, highly discriminative measure of similarity. © 2011Wiley Periodicals, Inc. Complexity, 2011     

Lower and upper regularizations of frame semicontinuous real functions

As discovered recently, Li and Wang’s 1997 treatment of semicontinuity for frames does not faithfully reflect the classical concept. In this paper we continue our study of semicontinuity in the pointfree setting. We define the pointfree concepts of lower and upper regularizations of frame semicontinuous real functions. We present characterizations of extremally disconnected frames in terms of these regularizations that allow us to reprove, in particular, the insertion and extension type characterizations of extremally disconnected frames due to Y.-M. Li and Z.-H. Li [Algebra Universalis 44 (2000), 271–281] in the right semicontinuity context. It turns out that the proof of the insertion theorem becomes very easy after having established a number of basic results regarding the regularizations. Notably, our extension theorem is a much strengthened version of Li and Li's result and it is proved without making use of the insertion theorem. The first and second named authors acknowledge financial support from the Ministry of Education and Science of Spain and FEDER under grant MTM2006-14925-C02-02. The first named author also acknowledges financial support from the University of the Basque Country under grant UPV05/101. The third named author acknowledges financial support from the Centre of Mathematics of the University of Coimbra/FCT.     

Pursuing new facts in the coordination capabilities of (1-diaminomethylene)thiourea (HATU): Products of the interaction with transition metal halides – Structural investigations

This work is part of our studies on the reactivity and crystal engineering of (1-diaminomethylene)thiourea (HATU). Structure and other properties of the selected products of the interaction of HATU with transition metal halides, also in the presence of 3% hydrogen peroxide as an oxidizing agent, have been investigated ((1) di-μ-((1-diaminomethylene)thiouron-1-ium)-κ⁴S:S-bis[chlorido((1-diaminomethylene)-thiouron-1-ium-κS)copper(I)] tetrachloride [(C₂H₇N₄S)₄Cu^I₂Cl₂]Cl₄, (2) catena(bis(3,5-diamino-1,2,4-thiadiazol-2-ium)-bis(μ₂-chlorido)-chloridocuprate(II)) [(C₂H₆N₄S)₂(Cu₂Cl₆)]_∞, (3) 3,5-diamino-1,2,4-thiadiazol-2-ium pentachloridoferrate(III) (C₂H₆N₄S)₂[FeCl₅], (4) 3,5-diamino-1,2,4-thiadiazol-2-ium chloride) (C₂H₆N₄S)Cl, (5) 3,5-diamino-1,2,4-thiadiazol-2-ium tetrachloridozincate(II) (C₂H₇N₄S)₂[ZnCl₄]. For (2) also magnetic properties have been characterized. Compound (3) contains unusual pentachloridoferrate(III) anions.     

Tricarbonylrhenium(I) complexes of highly symmetric hexaazatrinaphthylene ligands (HATN): structural, electrochemical and spectroscopic properties

The new mononuclear and dinuclear tricarbonylrhenium(I) complexes [(HATN)Re(CO)(3)Cl] (1-Cl) and [(μ-Me(6)-HATN)[Re(CO)(3)Cl](2)] (2-Cl(2)) of highly symmetric ligands HATN and Me(6)-HATN were synthesized and structurally characterized. X-Ray crystal structures reveal identical strained aromatic systems and out of the plane fac-Re(CO)(3)Cl units for both complexes. The packing geometry in the unit cell of 1 suggests intermolecular π-π association. Infrared spectroelectrochemistry (SEC) experiments confirmed ligand-based reductions. To get more insight into the reduction mechanism the triflate salts, [(HATN)Re(CO)(3)](OTf) (1-OTf) and [(μ-Me(6)HATN){Re(CO)(3)}(2)](OTf)(2) (2-OTf(2)), were synthesized. Their electrochemical and spectroelectrochemical behavior also exhibits reduction of the aromatic systems. The electronic absorption spectral features of the one electron reduced species were studied by UV-vis-NIR spectroscopy, which shows a broad shoulder at 1500 nm, confirming intra-ligand charge transfer (ILCT). Density functional theory (DFT) calculations on the complexes 1-Cl and 2-Cl(2) for structural optimization show good agreement with experimental bond lengths and bond angles. The spin density plot shows a metal based HOMO and HATN ligand centered LUMO.     

Structural investigations into the deactivation pathway of the CO2 reduction electrocatalyst Re(bpy)(CO)3Cl

We report a series of complexes synthesized from the chemical reduction of the fac-tricarbonyl complex Re(bpy)(CO)(3)Cl. Synthesis and characterization of [Re(bpy)(CO)(3)](2), [Re(bpy)(CO)(3)](2)(-), and Re(bpy)(CO)(3)(-) are presented. The Re(bpy)(CO)(3)(-) anion has long been postulated as the active species that reacts with carbon dioxide in the electrochemical reduction of CO(2).     

Metallophthalocyanine-catalyzed cyclopropanation

Metallophthalocyanine-catalyzed carbenoid reactions have had little attention to date. Recently these metal complexes have been found to catalyze cyclopropanation reactions. We have investigated these metallophthalocyanines in reactions to catalyze cyclopropanation from donor–acceptor carbenoids. The yields and diastereoselectivity of these reactions are influenced by the nature of the styrene as well as the aryldiazoacetate and catalyst. The products have been synthesized in short reaction times (1 h), with good yields (up to 84%), and high diastereoselectivity (up to 20:1 ratio cis/trans products).     

Degradation of Isoproturon in Soil in Relation to Changes of Microbial Biomass and Activity in Small-Scale Laboratory and Outdoor Studies

Abstract

The soil degradation of isoproturon under standardized laboratory conditions was compared to that carried out in an outdoor experiment using lysimeters. After application of ¹⁴C-labelled formulated isoproturon (1.5 kg A.I./ha), radiochemical analysis, as well as microbial investigations, were performed to relate changes in soil microbial biomass to its capability of degrading isoproturon. The results showed that the microbial biomass, as well as its dehydrogenase activity, varied under field conditions due to fluctuations of temperature and soil moisture. In the laboratory experiment the microbial biomass decreased during the 100 day experimental period, this reduction being the result of the experimental conditions. Consequently, the herbicide was degraded more quickly in the outdoor experiment where leaching, formation of ¹⁴CO₂ uptake by plants, and photolysis also took place, than in the laboratory experiment. Further microbiological investigation in the laboratory experiment showed that specific populations known to be responsible for the metabolic degradation of the compound were enhanced in the isoproturon-treated soil.     

Supramolecular motifs in the first structures of organic carboxylate salts of 1‐(diaminomethylene)thiourea (HATU)

The structures of the first two organic carboxylate salts of 1‐(diaminomethylene)thiourea (HATU), namely 1‐(diaminomethylene)thiouron‐1‐ium formate, C₂H₇N₄S⁺·HCOO⁻, (I), and bis[1‐(diaminomethylene)thiouron‐1‐ium] oxalate dihydrate, 2C₂H₇N₄S⁺·C₂O₄²⁻·2H₂O, (II), in which the oxalate lies on a symmetry centre, possess different extended hydrogen‐bonding networks with different graph‐set motifs. The R₂²(8) motif present in (I) does not appear in (II), but an R₂¹(6) motif is present in both (I) and (II). Compound (I) has a three‐dimensional hydrogen‐bonding network, whereas (II) has a layered structure with layers joined by hydrogen‐bonding motifs that form R₄²(8) patterns. This work extends the known supramolecular structural data for HATU to include these organic carboxylates in addition to the previously characterized salts with inorganic acids.