| 1. |
- Borel, Cédric, 1979, et al.
(författare)
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Oxalate- and Squarate-Biimidazole Supramolecular Synthons: Hydrogen-Bonded Networks Based on Co(H(2)biimidazole)(3) (3+)
- 2009
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7505 .- 1528-7483. ; 9:6, s. 2821-2827
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Tidskriftsartikel (refereegranskat)abstract
- The utility of R-2(2)(9) biimidazole-carboxylate, R-2(2)(10) biimidazole-oxalate/squarate and R-2(2) (9) biimidazole-(tris-oxalate) synthons is considered for crystal engineering of hydrogen-bonded networks based on [Co-III(H(2)biim)(3)](3+) cations (H(2)biim = 2,2-biimidazole) and oxalate, squarate or [M-III(C2O4)(3-) anions. Syntheses and crystal structures are described for [Co-III(H(2)biim)(3)](3-) [M-III(C2O4)(3)]center dot 2H(2)O (M = Cr, 1; M = Co, 2), [Co-III(H(2)biim)(3)](HC4O4)(3)center dot 2H(2)O, 3, and [Co-III(H(2)biim)(3)](C2O4)Cl center dot 5.5H(2)O, 4. Compounds 1 and 2 are isostructural and comprise [Co(H(2)biim)(3)](3+) cations bridged by [M(oxalate)(3)](3-) anions in two directions and water molecules in the third direction to give a 3D H-bonded network. Both outer and inner 0 atoms of the coordinated oxalate ions act as H-bond acceptors, forming motifs closely related to the anticipated R-2(2)(9) biimidazole-(tris-oxalate) synthon. Compound 3 contains a more complex H-bond pattern in 3D, built from the intended R-2(2)(10) biimidazole-squarate synthon and additional H-bonds between protonated squarate molecules and water molecules. The structure of compound 4 (obtained with synchrotron radiation) contains layers in which stacked pairs of oxalate anions bridge between [Co-III(H(2)biim)(3)](3+) cations to form a dense 2D kgd-net, separated by layers of disordered chloride anions and H-bonded water molecules.
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| 2. |
- Forsberg, Ulrika, et al.
(författare)
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Four New Synthetic Elements Approved
- 2016
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Ingår i: Kemivärlden, Biotech, Kemisk tidskrift. - 1650-0725. ; Februari 2016:1, s. 31-33
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Recently, chemists and physicists in the Joint Working Party (JWP) have approved the new elements, but what is the significance and how can we make use of elements that exist so fleetingly?
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| 3. |
- Ghazzali, Mohamed I D M, 1974, et al.
(författare)
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Synthesis, EPR and DFT calculations of rare Ag(II)porphyrins and the crystal structure of [Zn(II)tetrakis(4-bromo-2-thiophene)porphyrin]
- 2008
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Ingår i: Inorganic Chemistry Communication. - : Elsevier BV. - 1387-7003 .- 1879-0259. ; 11:9, s. 1019-1022
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Tidskriftsartikel (refereegranskat)abstract
- Meso-tetrakis (4-bromo-2-thiophene) and (5-bromo-2-thiophene) porphyrins were synthesized in 18% yield from freshly distilled pyrrole and the corresponding aldehydes in refluxing propionic acid. Reaction of both porphyrins with either Zn(OAc) 2 · 2H 2 O or Ag(OAc) afforded the corresponding metal complexes in 20% yield. The free bases and metal complexes were characterized by IR, NMR, EPR, MS and XPS. The crystal structure of 5,10,15,20(4-bromo-2-thiophene)porphyrinato Zn(II) was determined by X-ray diffraction and shows a 'zigzag-like' packing pattern due to S···S intermolecular interaction. Structural features of these molecules are discussed by DFT quantum chemical calculations. © 2008 Elsevier B.V. All rights reserved.
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| 4. |
- Johansson, Roger, et al.
(författare)
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Hydrogen bond control of dimensionality in organometallic {2,6-Bis[(di-t-butylphosphino)methyl]phenyl}palladium(II) compounds: Dimers, chains, and a 3D-net with an apparent channel structure
- 2007
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7505 .- 1528-7483. ; 7:10, s. 1974-1979
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Tidskriftsartikel (refereegranskat)abstract
- A number of derivatives of {2,6-bis[(di-t-butylphosphino)methyl]phenyl}palladium(II)(PCPPd) have been synthesized and characterized by X-ray diffraction, namely, PCPPdNO3 (3), PCPPdOH hydrate (4), and PCPPdNO2 pentane solvate (5). These compounds share a rigid backbone and have about 75 atoms each whereof 70 are arranged in exactly the same way in all compounds. Nevertheless, in the solid state they have completely different packing arrangements that seem to be the result of weak to medium strong hydrogen bonding. Thus, 4 forms fairly strongly hydrogen-bonded dimers involving solvent water, whereas 3 gives rise to weakly hydrogen-bonded zigzag chains. Finally, compound 5 makes a weakly hydrogen-bonded 3D quartz net that gives rise to hydrophobic channels filled with highly disordered pentane molecules. Attempts to remove the pentane ultimately result in crystal deterioration.
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| 5. |
- Johnson, Magnus, et al.
(författare)
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Neutral Organometallic Halogen Bond Acceptors: Halogen Bonding in Complexes of PCPPdX (X = Cl, Br, I) with Iodine (I(2)), 1,4-Diiodotetrafluorobenzene (F4DIBz), and 1,4-Diiodooctafluorobutane (F8DIBu)
- 2012
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7505 .- 1528-7483. ; 12:1, s. 362-368
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Tidskriftsartikel (refereegranskat)abstract
- The behavior of a sterically crowded neutral pincer {2,6-bis[(di-t-butylphosphino)methyll-phenyl}palladium (PCPPd) halides, PCPPdX (X = Cl, Br or I), as XB acceptors with strong halogen bond (XB) donors, iodine (I(2)), 1,4-diiodotetrafluorobenzene (F4DIBz), and 1,4-dliodooctafluorobutane (F8DIBu) were studied in the solid state. The co-crystallization experiments afforded high-quality single crystals of XB complexes PCPPdCl-I(2) (1a), PCPPdBr-I(2) (2a), PCPPdI-I(2) (3a), PCPPdCl-F4DD3z (lb), PCPPdBr-F4DIBz (2b), and PCPPdBr-F8DIBu (2c). The 1:1 iodine complexes (la, 2a, and 3a) all showed a strong halogen bonding interaction, the reduction of the sum of the van der Waals radii of halogen to iodine being 24.6 (la), 23.9 (2a), and 19.4% (3a) with X center dot center dot center dot I-I angles of 177, 176, and 179 degrees, respectively. While the pincer palladium chloride 1 and bromide 2 were crystallographically isomorphous and showed similar XB behavior, the palladium iodide complex, 3, exhibited markedly different properties, and unlike 1 and 2 it does not, under similar conditions, result in XB complexes with the weaker XB donors F4DIBz and F8D1Bu. The results indicate that PCPPd1 is not nucleophilic enough to have XB interactions with other donors than iodine. However, the weaker XB donors F4DIBz and F8DIBu form XB complexes with the chloride 1 and especially with the bromide 2. The prevalence of the halogen bonding with 2 is probably not only electronic in origin, and it seems to offer the best balance between electron poorness and steric availability. The X13 interactions with F4DIBz and F8DIBu are much weaker than with iodine, the reduction of the sum of the van der Wash radii of halogen to iodine being 13.5, 12.3, and 14.6% with C-I center dot center dot center dot X angles between 163 and 179 degrees for lb, 2b, and 2c, respectively, and results in polymeric (center dot center dot center dot 1 center dot center dot center dot F4DIBz center dot center dot center dot 1 center dot center dot center dot F4DIBz center dot center dot center dot center dot)(w) (center dot center dot center dot center dot 2 center dot center dot center dot center dot F4DIBz center dot center dot center dot center dot 2 center dot center dot center dot center dot F4DIBz center dot center dot center dot center dot)(w) and (center dot center dot center dot center dot 2 center dot center dot center dot center dot F8DIBu center dot center dot center dot center dot 2 center dot center dot center dot center dot F8DIBu center dot center dot center dot center dot)(N) one-dimensional zigzag chains in the solid state.
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| 6. |
- Johnson, Magnus, et al.
(författare)
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Preparation of potentially porous, chiral organometallic materials through spontaneous resolution of pincer palladium conformers
- 2013
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 42:23, s. 8484-8491
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the mechanism by which advanced materials assemble is essential for the design of new materials with desired properties. Here, we report a method to form chiral, potentially porous materials through spontaneous resolution of conformers of a PCP pincer palladium complex ({2,6-bis[(di-t-butyl-phosphino)methyl]phenyl}palladium(II)halide). The crystallisation is controlled by weak hydrogen bonding giving rise to chiral qtz-nets and channel structures, as shown by 16 such crystal structures for X = Cl and Br with various solvents like pentane and bromobutane. The fourth ligand (in addition to the pincer ligand) on palladium plays a crucial role; the chloride and the bromide primarily form hexagonal crystals with large 1D channels, whereas the iodide (presumably due to its inferior hydrogen bonding capacity) forms monoclinic crystals without channels. The hexagonal channels are completely hydrophobic and filled with disordered solvent molecules. Upon heating, loss of the solvent occurs and the hexagonal crystals transform into other non-porous polymorphs. Also by introducing a strong acid, the crystallisation process can be directed to a different course, giving several different non-porous polymorphs. In conclusion, a number of rules can be formulated dictating the formation of hexagonal channel structures based on pincer palladium complexes. Such rules are important for a rational design of future self-assembling materials with applications in storage and molecular recognition.
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| 7. |
- Larsson, Krister, 1973, et al.
(författare)
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Cobalt 2,2 '-biimidazole complexes co-crystallised with di-acids - synthesis, structure and quantum chemical calculations
- 2004
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Ingår i: Crystengcomm. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 6, s. 354-359
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis and crystal structure of [Co(Hbiim)(2)(H(2)biim)](2)(p-OOCC6H4COOH)(2).H2O (2) is presented. The cobalt(III) complexes are bridged by terephthalates and water molecules, giving a rare, five-fold interpenetrated, net built from 3-connected nodes. The vertex symbol (topology) of this net is determined to 4 122 122, 4 126, 12(4) 12(6) 12(6), or 4 12(2), 4 12(2), 12(3), using the Wellsian point symbol system. However, depending on the interpretation of the hydrogen bond pattern, this structure may also be interpreted as a single self-interpenetrating net via a water bridge. Quantum chemical calculations (DFT and semi-empirical methods) were used to investigate which is the more appropriate description by estimation of the directional forces in the structure. This approach favours five interpenetrating nets.
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| 8. |
- Stoncius, S., et al.
(författare)
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An approach to helical tubular self-aggregation using C-2-symmetric self-complementary hydrogen-bonding cavity molecules
- 2006
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 128:25, s. 8272-8285
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Tidskriftsartikel (refereegranskat)abstract
- In an approach to helical self-aggregation, C 2 -symmetric cavity compounds based on the fusion of the bicyclo[3.3.1]nonane and indole framework and incorporating two 2-pyridone hydrogen-bonding motifs, compounds (-)-4 (pyrrole N-butyl) and (-)-5 (pyrrole N-decyl), have been synthesized. The 2-pyridone AD-DA hydrogen-bonding motif failed to operate in the solid state as demonstrated by X-ray diffraction analysis of (-)-4. Instead, the hydrogen-bonded (D-A) chains ⋯O=C-N-H⋯O=C-N-H⋯O=C-N- H⋯, interconnecting columnar stacks, comprise helices of the right-handed (P) chirality motif. In solution, the aggregation of (-)-5 was studied by NMR, electronic, and CD spectroscopies, and VPO measurements. These investigations strongly suggest that (-)-5 associates to oligomers in CHCl 3 and CH 2 Cl 2 using the 2-pyridone motif, fitting the equal K model, and that π-stacking can be ruled out as a mode of aggregation. We conclude that the so formed aggregates of (-)-5 have a helical structure, based on the fact that only helical tubular structures can result when enantiomerically pure 5 uses its 2-pyridone AD-DA hydrogen-bonding motifs for aggregation. © 2006 American Chemical Society.
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| 9. |
- Stoncius, S., et al.
(författare)
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Design and synthesis of a C-2-symmetric self-complementary hydrogen-bonding cleft molecule based on the bicyclo 3.3.1 nonane and 4-oxo-5-azaindole framework. Formation of channels and inclusion complexes in the solid state
- 2004
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 69:16, s. 5196-5203
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis of a C-2-symmetric cleft molecule 2 based on the fused framework between bicyclo-[3.3. 1] nonane and 4-oxo-5-azaindole, incorporating a self-complementary hydrogen-bonding motif, in both racemic and enantiomerically pure forms is reported. This cleft molecule is reminiscent of analogues of Troger's base though with different cleft dimensions and tilt angles. The framework of 2 provides a building block for the construction of self-assembled hydrogen-bonded supramolecular structures. The solid-state structure of 2 is highly influenced by the limited solubility of (+/-)-2 and (-)-2. The solvents interact with the potential hydrogen-bonding motifs of (+/-)-2 and (-)-2, forming different three-dimensional structures as revealed by X-ray diffraction analysis. In the solid state (+/-)-(2)(2)(.)5DMF forms hydrogen-bonded pleated band structures that build up three-dimensional pens between adjacent bands in which two molecules of DMF are trapped. In contrast, the aggregate obtained from (-)-2, (-)-2(.)2AcOH, showed infinite bands of complex constitution.
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| 10. |
- Wallentin, Carl-Johan, et al.
(författare)
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Network analysis of bicyclo 3.3.1 nonanes: the diol, the dione and the acetal
- 2009
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Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 11:9, s. 1837-1841
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Tidskriftsartikel (refereegranskat)abstract
- The solid state structure of endo,endo-bicyclo[3.3.1]nonane-2,6-diol, rac-2, shows a hydrogen bonded, three-connected, chiral 3D-net with utg-topology, distinctively different from those formed by the so called tubuland diols, e.g. 2,6-dimethylbicyclo[3.3.1]nonane-exo2, exo-6-diol, rac-5, that crystallise as three-connected, chiral etanets and from the qtz-net formed by weaker hydrogen bonds in the bicyclo[3.3.1]nonane-2,6-dione, 3. The protected bicyclo[3.3.1]nonane2,6-dione, bis-2,6-ethylenedioxy acetal, 4, has a structure governed by weaker forces and can be interpreted as close packed stacks.
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