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Half Molecules (half + molecule)
Selected AbstractsAttenuation of half sulfur mustard gas-induced acute lung injury in ratsJOURNAL OF APPLIED TOXICOLOGY, Issue 2 2006Shannon D. McClintock Abstract Airway instillation into rats of 2-chloroethyl ethyl sulfide (CEES), the half molecule of sulfur mustard compound, results in acute lung injury, as measured by the leak of plasma albumin into the lung. Morphologically, early changes in the lung include alveolar hemorrhage and fibrin deposition and the influx of neutrophils. Following lung contact with CEES, progressive accumulation of collagen occurred in the lung, followed by parenchymal collapse. The co-instillation with CEES of liposomes containing pegylated (PEG)-catalase (CAT), PEG-superoxide dismutase (SOD), or the combination, greatly attenuated the development of lung injury. Likewise, the co-instillation of liposomes containing the reducing agents, N-acetylcysteine (NAC), glutathione (GSH), or resveratrol (RES), significantly reduced acute lung injury. The combination of complement depletion and airway instillation of liposomes containing anti-oxidant compounds maximally attenuated CEES-induced lung injury by nearly 80%. Delayed airway instillation of anti-oxidant-containing liposomes (containing NAC or GSH, or the combination) significantly diminished lung injury even when instillation was delayed as long as 1 h after lung exposure to CEES. These data indicate that CEES-induced injury of rat lungs can be substantially diminished by the presence of reducing agents or anti-oxidant enzymes delivered via liposomes. Copyright © 2005 John Wiley & Sons, Ltd. [source] Concomitant polymorphic behavior of di-,-thiocyanato-,2N:S;,2S:N -bis[bis(tri- p -fluorophenylphosphine-,P)silver(I)]ACTA CRYSTALLOGRAPHICA SECTION B, Issue 1 2010Bernard Omondi The structures of two polymorphs, both monoclinic P21/n [polymorph (I)] and P21/c [polymorph (II)], of di-,-thiocyanato-,2N:S;,2S:N -bis[bis(tri- p -fluorophenylphosphine-,P)silver(I)] complexes have been determined at 100,K. In both polymorphs the complex has a dinuclear structure where the silver(I) coordinates to two phosphine ligands and two bridging thiocyanate anions to form complexes with distorted tetrahedral geometry. Polymorph (I) has just one half of the [Ag2(SCN)2{P(4-FC6H4)3}4] molecule at (0, ½, 0) from the origin in the asymmetric unit. Polymorph (II) has one and a half molecules of [Ag2(SCN)2{P(4-FC6H4)3}4] in the asymmetric unit; the half molecule is situated at (0, 1, ½), while the full molecule is located at (1/3, ½, 1/3) from the origin. The Ag,P bond distances range from 2.4437,(4) to 2.4956,(7),Å in both polymorphs. The Ag,S distances are 2.5773,(7),Å in (I) and 2.5457,(5), 2.5576,(5) and 2.5576,(5),Å in (II). The full molecule in polymorph (II) has slightly shorter Ag,N bond distances [2.375,(1) and 2.367,(2),Å] compared with the half molecules in both polymorphs [2.409,(2),Å in (II) and 2.395,(2),Å in (I)]. The two polymorphs are compared using r.m.s. overlay calculations as well as half-normal probability plot analysis. [source] Structural Diversity in Organotin Compounds Derived from Bulky Monoaryl Phosphates: Dimeric, Tetrameric, and Polymeric Tin Phosphate ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2008Ramaswamy Murugavel Abstract Monoaryl phosphates with a bulky aryl substituent have been used to synthesize new organotin clusters and polymers. The equimolar reaction between 2,6-diisopropylphenylphosphate (dipp-H2) and Me2SnCl2 in ethanol at 25 °C leads to the formation of [Me2Sn(,3 -dipp)]n (1), while the reaction of 2,6-dimethylphenylphosphate (dmpp-H2) with Me2SnCl2 in either a 1:1 or 2:1 molar ratio proceeds to produce exclusively [Me2Sn(,-dmpp-H)2]n·nH2O (2). Compounds 1 and 2 are 1D polymers with different architectures. In compound 1, the tin atom is five-coordinate (trigonal bipyramidal). Each dipp ligand bridges three different tin atoms to form an infinite ladder-chain structure. In 2, each six-coordinate (octahedral) tin atom is surrounded by four phosphate oxygen atoms originating from four different bridging dmpp-H ligands, thus forming a spirocyclic coordination polymeric chain. The use of nBu2SnO as the diorganotin source in its reaction with dipp-H2 leads to the isolation of dimeric [nBu2Sn(,-dipp-H)(dipp-H)]2 (4), which contains a central Sn2O4P2 unit. There are two chemically different half molecules of 4 in the asymmetric part of the unit cell and hence it actually exists as a 1:1 mixture of [nBu2Sn(,-dipp-H)(dipp-H)]2 and [nBu2Sn(,-dipp)(dipp-H2)]2 in the solid state. The reaction of the monoorgano tin precursor nBuSn(O)(OH)·xH2O with dipp-H2 takes place in acetone at room temperature to yield the tetrameric cluster 5, which has different structures in the solution and in the solid state. 31P NMR spectroscopy clearly suggests that 5 has the formula [nBu4Sn4(,-O)2(,-dipp-H)8] in solution. The single-crystal X-ray diffraction studies in the solid state, however, reveal that compound 5 exists as [nBu4Sn4(,-OH)2(,-dipp-H)6(,-dipp)2]. The use of compounds 1,4 as possible precursors for the preparation of ceramic tin phosphate materials has been investigated. The thermolysis of 1 at 500 °C leads to the formation of quantitative amounts of Sn2P2O7, while the thermolysis of 2, 3, and 4 under similar conditions results in the formation of SnP2O7. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Concomitant polymorphic behavior of di-,-thiocyanato-,2N:S;,2S:N -bis[bis(tri- p -fluorophenylphosphine-,P)silver(I)]ACTA CRYSTALLOGRAPHICA SECTION B, Issue 1 2010Bernard Omondi The structures of two polymorphs, both monoclinic P21/n [polymorph (I)] and P21/c [polymorph (II)], of di-,-thiocyanato-,2N:S;,2S:N -bis[bis(tri- p -fluorophenylphosphine-,P)silver(I)] complexes have been determined at 100,K. In both polymorphs the complex has a dinuclear structure where the silver(I) coordinates to two phosphine ligands and two bridging thiocyanate anions to form complexes with distorted tetrahedral geometry. Polymorph (I) has just one half of the [Ag2(SCN)2{P(4-FC6H4)3}4] molecule at (0, ½, 0) from the origin in the asymmetric unit. Polymorph (II) has one and a half molecules of [Ag2(SCN)2{P(4-FC6H4)3}4] in the asymmetric unit; the half molecule is situated at (0, 1, ½), while the full molecule is located at (1/3, ½, 1/3) from the origin. The Ag,P bond distances range from 2.4437,(4) to 2.4956,(7),Å in both polymorphs. The Ag,S distances are 2.5773,(7),Å in (I) and 2.5457,(5), 2.5576,(5) and 2.5576,(5),Å in (II). The full molecule in polymorph (II) has slightly shorter Ag,N bond distances [2.375,(1) and 2.367,(2),Å] compared with the half molecules in both polymorphs [2.409,(2),Å in (II) and 2.395,(2),Å in (I)]. The two polymorphs are compared using r.m.s. overlay calculations as well as half-normal probability plot analysis. [source] p -Phenylenediamine and its dihydrate: two-dimensional isomorphism and mechanism of the dehydration process, and N,H...N and N,H..., interactionsACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2010Agnieszka Czapik p -Phenylenediamine can be obtained as the dihydrate, C6H8N2·2H2O, (I), and in its anhydrous form, C6H8N2, (II). The asymmetric unit of (I) contains one half of the p -phenylenediamine molecule lying about an inversion centre and two halves of water molecules, one lying on a mirror plane and the other lying across a mirror plane. In (II), the asymmetric unit consists of one molecule in a general position and two half molecules located around inversion centres. In both structures, the p -phenylenediamine molecules are arranged in layers stabilized by N,H..., interactions. The diamine layers in (I) are isostructural with half of the layers in (II). On dehydration, crystals of (I) transform to (II). Comparison of their crystal structures suggests the most plausible mechanism of the transformation process which requires, in addition to translational motion of the diamine molecules, in-plane rotation of every fourth p -phenylenediamine molecule by ca 60°. A search of the Cambridge Structural Database shows that the formation of hydrates by aromatic amines should be considered exceptional. [source] A new polymorph of poly[bis(,2 -perchlorato-,2O:O,)(2,2,:6,,2,,-terpyridine-,3N,N,,N,,)lead(II)] with a greatly extended chain repeat distanceACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2009Alexander J. Blake In the title compound, [Pb(ClO4)2(C15H11N3)]n, two molecules occupy general positions while the third lies on a crystallographic twofold axis, giving a total of two and a half molecules per asymmetric unit. Each metal centre is coordinated equatorially by three 2,2,:6,,2,,-terpyridine (terpy) N-donor atoms and axially by two perchlorate O-donor atoms. The distorted pentagonal bipyramidal geometry is completed by two equatorial O-donor atoms from two perchlorate anions which bridge to two different adjacent metal centres. The coordination about each metal centre is very similar to that seen at the unique PbII centre in the previously published polymorph [Engelhardt, Harrowfield, Miyamae, Patrick, Skelton, Soudi & White (1996). Aust. J. Chem.49, 1135,1146], but the new polymorph differs from it by the insertion on each side of an existing [bis(perchlorato)(terpy)lead(II)] molecule of two additional such units. Pairs of asymmetrically bridging perchlorate anions link irregularly spaced PbII centres into undulating chains parallel to [201] which exhibit a repeat distance of 26.280,(4),Å. The significance of this new polymorph lies in the fact that, while it is chemically identical to the known polymorph, it is structurally distinct from it. [source] | ||||||||||