uu.seUppsala universitets publikationer
Ändra sökning
Avgränsa sökresultatet
123 1 - 50 av 122
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Alvi, Muhammad Rouf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Low-coordinate Organosilicon Chemistry: Fundamentals, Excursions Outside the Field, and Potential Applications2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis reports on unsaturated silicon compounds, as well as excursions from these into germanium chemistry, single molecule electronics, and silyl protective group chemistry. Both experimental and computational investigations were performed.

    Potassium germenolates were synthesized through reactions of tris(timethylsilyl) substituted acyl- and carbamylgermanes with potassium tert-butoxide. The potassium germenolates calculated by density functional theory have pyramidal structures at the Ge atoms, similar to the Si in the corresponding potassium silenolates, indicating negative charge on germanium rather than on oxygen. Germenolates also display germyl anion-like reactivity instead of germene-like reactivity as they are alkylated at Ge and initiate anionic polymerization of dienes rather than form [4+2] cycloadducts. The NMR chemical shifts reveal more negative charge at Ge in germenolates than at Si in analogous silenolates.

    Computations indicate that silabenzenes and silapyridines are reachable via [1,3]-silyl shifts from cyclic conjugated acylsilanes. Differently sized substituents were considered to prevent dimerizations, and 1-triisopropylsilyl-2-triisopropylsiloxy-6-tert-butylsilabenzene is a good synthetic target. Computations also show that silaphenolates are species with negative charge primarily localized at oxygen atom. Their planar structures, bond lengths, and NICS values reveal significant influence of aromaticity. Electrostatic repulsion should increase their stability, however, steric bulk is also important.

    Furthermore, it was found computationally that [1,3]-silyl shift from an acylsilane to a silene can function as a molecular switch reaction. Conductance calculations support this proposition.  

    Finally, tris(trimethylsilyl)silylmethaneamide (hypersilylamide) together with catalytic amounts of triflic acid were found to be efficient for protection of a range of alkyl and aryl alcohols and thiols in good to excellent yields. The protocol can be used to protect the less hindered OH group of a diol and has a broad functional group tolerance. A catalytic cycle is proposed. Hypersilyl protected alcohols and thiols are deprotected efficiently under photolytic conditions.

    Delarbeten
    1. Remarkably Stable Silicon Analogues of Amide Enolates: Synthesis, Structural Characterization, and Reactivity Studies
    Öppna denna publikation i ny flik eller fönster >>Remarkably Stable Silicon Analogues of Amide Enolates: Synthesis, Structural Characterization, and Reactivity Studies
    Visa övriga...
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Potassium 2-N,N-dialkylamino-1,1-bis(trimethylsilyl)silen-2-olates (or amide silenolates, silicon analogues of amide enolates) were synthesized through reaction of N,N-dialkyl-tris(trimethylsilyl)silylmethaneamides with potassium tert-butoxide, and these 2-N,N-dialkylaminosilen-2-olates display remarkable thermal stabilities (e.g., merely 37% decomposition after 8 h at 90 ºC).  The crystal structure of one of the potassium 2-N,N-dialkylaminosilen-2-olates, without potassium ion chelating agent, reveals a more pyramidal configuration around the Si atom than found in previously reported silenolates, indicating a strong localization of the negative charge to this atom. The reactivities of the potassium 2-N,N-dialkylaminosilen-2-olates are in part similar to those of previous lithium and potassium silenolates as they are alkylated with MeI at Si. However, they do not react with dienes to yield [4+2] cycloadducts, the customary adducts of silenolates and reverse polarized silenes, but instead initiate anionic diene polymerization.  Consequently, they display silyl anion-like rather than silene-like reactivities. Finally, we find that potassium 2-aminosilen-2-olates with N,N-diphenylamino instead of N,N-dialkylamino substitution decompose rapidly to potassium diphenylamide, carbon monoxide, and silylenes. Clearly, if the substituent at the 2-position of a silenolate is able to accept and stabilize negative charge, such as NPh2, then this silenolate will be prone to decompose.

    Nationell ämneskategori
    Organisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-169783 (URN)
    Tillgänglig från: 2012-03-06 Skapad: 2012-03-06 Senast uppdaterad: 2012-04-19
    2. Formation and Fundamental Properties of Potassium Germen-2-olates
    Öppna denna publikation i ny flik eller fönster >>Formation and Fundamental Properties of Potassium Germen-2-olates
    Visa övriga...
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Potassium 1,1-bis(trimethylsilyl)germen-2-olates (2a - 2d) with different substituents at the carbon atom were generated in good yields through the treatment of the correspondingly substituted tris(trimethylsilyl)acyl- and tris(trimethylsilyl)carbamyl-germanes (1a - 1d) with potassium tert-butoxide at room temperature in dry THF. Comparisons between the 29Si and 13C NMR chemical shifts of the germenolates and the analogous silenolates (4a4d) were performed. The recorded 13C and 29Si NMR chemical shifts of the potassium germenolates were also compared to those obtained from GIAO-B3LYP/6-31+G(d)//B3LYP/LANL2DZp calculations. The chemical reactivities of potassium germenolates were compared with silenolates. In this regard, the reactions of 2a - 2d were performed with methyliodide at -40 oC and the germanium methylated products (5a - 5c) were obtained in yields of 54 - 77 %. The reactions of these germenolates with 1,3-butadiene at low temperatures, however, lead to polymerization of dienes (2,3-dimethyl-1,3-butadiene, isoprene, and 1,3-pentadiene) revealing a reactivity resemblance to aminosilenolates, species which in return are comparable to silyl anions in reactivity.

    Nationell ämneskategori
    Organisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-169795 (URN)
    Tillgänglig från: 2012-03-06 Skapad: 2012-03-06 Senast uppdaterad: 2012-04-19
    3. Computational Investigation of Brook-Type Silabenzenes and Their Possible Formation through [1,3]-Si -> O Silyl Shifts
    Öppna denna publikation i ny flik eller fönster >>Computational Investigation of Brook-Type Silabenzenes and Their Possible Formation through [1,3]-Si -> O Silyl Shifts
    2013 (Engelska)Ingår i: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 32, nr 1, s. 16-28Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Quantum chemical calculations with the M062X hybrid meta density functional theory method were performed in order to examine formation of Brook-type silabenzenes 4a 4l, silapyridines 6a 6d, and five-membered ring silaheteroaromatics 8a8d through [1,3]-trimethylsilyl (TMS) and [1,3]-tri(isopropyl)silyl (TIPS) shifts from a tetrahedral silicon atom to an adjacent carbonyl oxygen of cyclic conjugated acylsilane precursors. All Brook-type silabenzenes and silapyridines, having a 2-trialkylsiloxy substituent, are at lower relative energies than their precursors, whereas silaheteroaromatics 8a 8d are found at slightly higher energies. The free energies of activation for the thermal [1,3]-TMS shifts range from 29 to 44 kcal/mol, with the lowest for a Brook-type silapyridine and the highest for a silafuran. The geometries of the Brook-type silabenzenes, silapyridines, silafuran and silathiophene indicate aromatic character, but the silapyrroles are nonaromatic. At M062X/6-311+G(d)//M062X/6-31G(d) level all Brook-type silabenzene dimers studied herein are more stable than two silabenzenes, also for a silabenzene with bulky TIPS, OTIPS and tert-butyl substituents (4l). Yet, comparisons of the B3LYP/6-31G(d) dimerization energies of 4l with that of the isolable 1-Tbt-silabenzene (Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl) of Tokitoh [J. Chin. Chem. Soc. 2008, 55, 487] indicate that 4l will also be a monomeric silabenzene, and thus, a suitable synthetic target.

    Nationell ämneskategori
    Organisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-169784 (URN)10.1021/om300023s (DOI)000313606200005 ()
    Tillgänglig från: 2012-03-06 Skapad: 2012-03-06 Senast uppdaterad: 2017-12-07Bibliografiskt granskad
    4. Silaphenolates and Silaphenylthiolates: Two Unexplored Unsaturated Silicon Compound Classes Influenced by Aromaticity
    Öppna denna publikation i ny flik eller fönster >>Silaphenolates and Silaphenylthiolates: Two Unexplored Unsaturated Silicon Compound Classes Influenced by Aromaticity
    2012 (Engelska)Ingår i: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 17, nr 1, s. 369-389Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Monosilicon analogs of phenolates and phenylthiolates are studied by quantum chemical calculations. Three different silaphenolates and three different silaphenylthiolates are possible; the ortho-, meta-, and para-isomers. For the silaphenolates, the meta- isomer is the thermodynamically most stable, regardless if the substituent R at Si is H, t-Bu or SiMe3. However, with R = H and SiMe3 the energy differences between the three isomers are small, whereas with R = t-Bu the meta- isomer is similar to 5 kcal/mol more stable than the ortho- isomer. For the silaphenylthiolates the ortho- isomer is of lowest energy, although with R = H the ortho- and meta- isomers are isoenergetic. The calculated nucleus independent chemical shifts (NICS) indicate that the silaphenolates and silaphenylthiolates are influenced by aromaticity, but they are less aromatic than the parent silabenzene. The geometries and charge distributions suggest that all silaphenolates and silaphenylthiolates to substantial degrees are described by resonance structures with an exocyclic C=O double bond and a silapentadienyl anionic segment. Indeed, they resemble the all-carbon phenolate and phenylthiolate. Silaphenylthiolates are less bond alternate and have slightly more negative NICS values than analogous silaphenolates, suggesting that this compound class is a bit more aromatic. Dimerization of the silaphenolates and silaphenylthiolates is hampered due to intramolecular Coulomb repulsion in the dimers, and silaphenolates with a moderately bulky SiMe3 group as substituent at Si should prefer the monomeric form.

    Nyckelord
    silicon, aromaticity, quantum chemical calculations
    Nationell ämneskategori
    Organisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-166896 (URN)10.3390/molecules17010369 (DOI)000299535700025 ()
    Tillgänglig från: 2012-01-16 Skapad: 2012-01-16 Senast uppdaterad: 2017-12-08Bibliografiskt granskad
    5. The [1,3]-Si→O Silyl Shift from a Nonconducting Acylsilane to a Conducting Brook-Silene as Basis for a Molecular Switch
    Öppna denna publikation i ny flik eller fönster >>The [1,3]-Si→O Silyl Shift from a Nonconducting Acylsilane to a Conducting Brook-Silene as Basis for a Molecular Switch
    Visa övriga...
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    By usage of density functional theory (DFT) calculations we explored if the [1,3]-silyl shift leading from an acylsilane with two p-conjugated substituents to a silene (a Si=C double bonded compound) can be used as a basis for a molecular conductance switch. In such a switch, the acylsilane, with a tetrahedral saturated silicon atom disrupting the conjugation through the molecule, acts as the OFF state, whereas the silene with a conjugated path running through the complete molecule represents the ON state. Our requirements are (i) the silenes should be slightly higher in relative energy than the acylsilane so as to promote a thermal backrearragment, (ii) the barrier for the backtransfer of the silyl group should be 25-30 kcal/mol, (iii) the ON/OFF conductance ratio should be high, and (iv) the switch should be realistic. According to our calculations using non-equilibrium Green’s function theory, a 1,2-bis(4-thiophenylethynyl)silene has a conductance which is 270 times higher than that of the corresponding acylsilane at zero bias voltage. However, at a voltage of +1 V the ON/OFF ratio decreases to ~40.

    Nationell ämneskategori
    Organisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-169782 (URN)
    Tillgänglig från: 2012-03-06 Skapad: 2012-03-06 Senast uppdaterad: 2012-04-19
    6. Highly Efficient and Convenient Acid Catalyzed Hypersilyl Protection of Alcohols and Thiols by Tris(trimethylsilyl)silyl-N,N-dimethylmethaneamide
    Öppna denna publikation i ny flik eller fönster >>Highly Efficient and Convenient Acid Catalyzed Hypersilyl Protection of Alcohols and Thiols by Tris(trimethylsilyl)silyl-N,N-dimethylmethaneamide
    Visa övriga...
    2012 (Engelska)Artikel i tidskrift (Övrigt vetenskapligt) Submitted
    Abstract [en]

    Tris(trimethylsilyl)silyl-N,N-dimethylmethaneamide, herein named hypersilylamide, is a convenient and efficient source of the hypersilyl group in the first widely applicable acid catalyzed protocol for silyl group protection of primary, secondary, tertiary alkyl as well as aryl alcohols and thiols in high yields. The sole by-product is N,N-dimethylformamide (DMF) and a range of solvents can be used, including DMF. A high selectivity in the protection of diols can be achieved, also for diols with very small differences in the steric demands at the two hydroxyl groups. Moreover, in the protection of equivalent alcohol and thiol sites the protection of the alcohol is faster, allowing for selective protection in high yields. Quantum chemical calculations at the M062X hybrid meta density functional theory level give insights on the mechanism for the catalytic process. Finally, the hypersilyl group is easily removed from all protected alcohols and thiols examined herein by irradiation at 254 nm.

    Nationell ämneskategori
    Organisk kemi Oorganisk kemi
    Forskningsämne
    Kemi med inriktning mot oorganisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-169781 (URN)
    Tillgänglig från: 2012-03-06 Skapad: 2012-03-06 Senast uppdaterad: 2013-03-07Bibliografiskt granskad
    7. Scope and Limitations of an Acid Catalyzed Protocol for Hypersilyl Protection of Alcohols
    Öppna denna publikation i ny flik eller fönster >>Scope and Limitations of an Acid Catalyzed Protocol for Hypersilyl Protection of Alcohols
    Visa övriga...
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    A highly efficient and convenient triflic acid (TfOH) catalyzed protocol for the protection of various functionalized alcohols in CH2Cl2 at ambient temperature using tris(trimethylsilyl)silyl-N,N-dimethyl-methaneamide (hypersilylamide) 1 as the protecting reagent is developed. Herein, results on the scope and limitations of this protocol for a number of functionalized alcohols are presented. This method was found to be effective for the selective protection of less hindered OH groups in different classes of diols containing both pri/tert, sec/tert, or aromatic/aliphatic hydroxyl groups. In general, our protocol exhibited excellent functional group tolerance in the protection of alcohols containing alkoxy, keto, amino, as well as halo substituents in good to excellent yields.

    Nationell ämneskategori
    Organisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-169780 (URN)
    Tillgänglig från: 2012-03-06 Skapad: 2012-03-06 Senast uppdaterad: 2012-04-19
  • 2.
    Alvi, Muhammad Rouf
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Burkhard O., Jahn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC.
    Ottosson, Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Computational Investigation of Brook-Type Silabenzenes and Their Possible Formation through [1,3]-Si -> O Silyl Shifts2013Ingår i: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 32, nr 1, s. 16-28Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Quantum chemical calculations with the M062X hybrid meta density functional theory method were performed in order to examine formation of Brook-type silabenzenes 4a 4l, silapyridines 6a 6d, and five-membered ring silaheteroaromatics 8a8d through [1,3]-trimethylsilyl (TMS) and [1,3]-tri(isopropyl)silyl (TIPS) shifts from a tetrahedral silicon atom to an adjacent carbonyl oxygen of cyclic conjugated acylsilane precursors. All Brook-type silabenzenes and silapyridines, having a 2-trialkylsiloxy substituent, are at lower relative energies than their precursors, whereas silaheteroaromatics 8a 8d are found at slightly higher energies. The free energies of activation for the thermal [1,3]-TMS shifts range from 29 to 44 kcal/mol, with the lowest for a Brook-type silapyridine and the highest for a silafuran. The geometries of the Brook-type silabenzenes, silapyridines, silafuran and silathiophene indicate aromatic character, but the silapyrroles are nonaromatic. At M062X/6-311+G(d)//M062X/6-31G(d) level all Brook-type silabenzene dimers studied herein are more stable than two silabenzenes, also for a silabenzene with bulky TIPS, OTIPS and tert-butyl substituents (4l). Yet, comparisons of the B3LYP/6-31G(d) dimerization energies of 4l with that of the isolable 1-Tbt-silabenzene (Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl) of Tokitoh [J. Chin. Chem. Soc. 2008, 55, 487] indicate that 4l will also be a monomeric silabenzene, and thus, a suitable synthetic target.

  • 3.
    Alvi, Muhammad Rouf
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Jahn, Burkhard O.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC.
    Tibbelin, Julius
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC.
    Baumgartner, Judith
    Institut für Anorganische Chemie, Technische Universität Graz, Stremayrgasse 9, A-8010 Graz, Austria.
    Gómez, Cesar Pay
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Ottosson, Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Highly Efficient and Convenient Acid Catalyzed Hypersilyl Protection of Alcohols and Thiols by Tris(trimethylsilyl)silyl-N,N-dimethylmethaneamide2012Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Tris(trimethylsilyl)silyl-N,N-dimethylmethaneamide, herein named hypersilylamide, is a convenient and efficient source of the hypersilyl group in the first widely applicable acid catalyzed protocol for silyl group protection of primary, secondary, tertiary alkyl as well as aryl alcohols and thiols in high yields. The sole by-product is N,N-dimethylformamide (DMF) and a range of solvents can be used, including DMF. A high selectivity in the protection of diols can be achieved, also for diols with very small differences in the steric demands at the two hydroxyl groups. Moreover, in the protection of equivalent alcohol and thiol sites the protection of the alcohol is faster, allowing for selective protection in high yields. Quantum chemical calculations at the M062X hybrid meta density functional theory level give insights on the mechanism for the catalytic process. Finally, the hypersilyl group is easily removed from all protected alcohols and thiols examined herein by irradiation at 254 nm.

  • 4.
    Andersson, Claes-Henrik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Grennberg, Helena
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Synthesis and characterization of a ferrocene-linked bis-fullerene[60] dumbbell2012Ingår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 41, nr 8, s. 2374-2381Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new [60]fullerene dumbbell consisting of two fulleropyrrolidines connected to a central ferrocene unit by amide linkages has been prepared and fully characterized by elemental analysis, 1H NMR, UV/Vis, fluorescence and mass spectrometry. The electrochemical properties as determined by cyclic voltammetry show ground state electronic communication between the ferrocene and the fullerene units. In addition, the preparaton of a ferrocene building block for an alternative linking approach is presented.

  • 5.
    Ankner, Tobias
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Norberg, Thomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC.
    Kihlberg, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Mild Oxidative Cleavage of 9-BBN-Protected Amino Acid Derivatives2015Ingår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 17, s. 3767-3770Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Protection of the amino acid moiety using 9-BBN is an effective method to enable side chain manipulations in synthesis of complex amino acids. We investigated the standard, mild method for deprotection of the 9-BBN group in methanolic chloroform, and found that it relies on a slow oxidation mediated by molecular oxygen. Building on this insight, we have developed a method that allows for a fast and selective deprotection using simple peroxy acid reagents. After Fmoc protection, products were isolated in >90% yield for a series of amino acid derivatives, including a galactosylated derivative of hydroxylysine.

  • 6.
    Appel, Lieuwe
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för radiologi, onkologi och strålningsvetenskap, Enheten för nuklearmedicin och PET.
    Bergström, Mats
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaci.
    Lassen, Jorgen Buus
    Långström, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Tesofensine, a novel triple monoamine re-uptake inhibitor with anti-obesity effects: Dopamine transporter occupancy as measured by PET2014Ingår i: European Neuropsychopharmacology, ISSN 0924-977X, E-ISSN 1873-7862, Vol. 24, nr 2, s. 251-261Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Tesofensine (TE) is a novel triple monoannine re-uptake inhibitor inducing a potent inhibition of the re-uptake process in the synaptic cleft of the neurotransmitters dopamine, norepinephrine, and serotonin. In recent preclinical and clinical evaluations TE showed a robust anti-obesity effect, but the specific mechanism of this triple monoamine re-uptake inhibitor still needs to be further elucidated. This positron emission tomography (PET) study, using [C-11]beta CIT-FE, aimed to assess the degree of the dopamine transporter (DAT) occupancy, at constant TE plasma levels, following different oral, multiple doses of TE during totally 8-12 days. In addition, the relationships between DAT occupancy and TE plasma concentrations, or doses, were investigated to enable assessment of DAT occupancies in subsequent clinical trials. The results demonstrated that TE induced a dose-dependent blockade of DAT following multiple doses of 0.125-1 mg TE at anticipated steady-state conditions. The mean striatal DAT occupancy varied dose-dependently between 18% and 77%. A signnoid E-max model well described the relationship between striatal DAT occupancy and TE plasma concentrations or doses. It was estimated that the maximum achievable DAT occupancy was about 80% and that half of this effect was accomplished by approximately 0.25 mg TE and a plasma drug concentration of 4 ng/ml. The results indicated an important mechanism of action of TE on DAT. Further, these results suggest that the previously reported dose-dependent weight loss, in TE treated subjects, was in part mediated by an up-regulation of dopaminergic pathways due to enhanced amounts of synaptic dopamine after blockade of DAT.

  • 7.
    Arkhypchuk, Anna I.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Mijangos, Edgar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Ott, Sascha
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Redox Switching in Ethenyl- Bridged Bisphospholes2014Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, nr 49, s. 16083-16087Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A 2e(-)/2H(+) redox platform has been implemented in the ethenyl-bridged bisphosphol-3-ol 1 to afford the first phospholes that feature chemically reversible oxidations. Oxidation of the title compounds to the corresponding bisphosphol-3-one 2 leads to a change in conjugation topology and a concomitant hypsochromic shift of the lowest-energy absorption maximum by 100nm. Electrochemical oxidation proceeds without any detectable intermediates, whereas the deprotonated form of 1 can be observed in an aprotic medium during the reduction of 2. This dianionic intermediate 3 is characterized by end absorptions that are bathochromically shifted by circa 200nm compared to those of 2.

  • 8.
    Bergman, Sara
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Avdelningen för organisk farmaceutisk kemi. Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Plattformen för preklinisk PET.
    Estrada, Sergio
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Plattformen för preklinisk PET.
    Hall, Håkan
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Plattformen för preklinisk PET.
    Rahman, Rashidur
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Plattformen för preklinisk PET.
    Blomgren, Andreas
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Avdelningen för organisk farmaceutisk kemi.
    Larhed, Mats
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Plattformen för preklinisk PET. Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Avdelningen för organisk farmaceutisk kemi.
    Svedberg, Marie
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Plattformen för preklinisk PET. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Thibblin, Alf
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Plattformen för preklinisk PET.
    Wångsell, Fredrik
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Avdelningen för organisk farmaceutisk kemi.
    Antoni, Gunnar
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Plattformen för preklinisk PET. Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för radiologi, onkologi och strålningsvetenskap, Enheten för onkologi.
    Synthesis and Labelling of a Piperazine-Based Library of 11C-Labeled Ligands for Imaging of the Vesicular Acetylcholine Transporter2014Ingår i: Journal of labelled compounds & radiopharmaceuticals, ISSN 0362-4803, E-ISSN 1099-1344, Vol. 57, nr 8, s. 525-532Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The cholinergic system is involved in neurodegenerative diseases, and visualization of cholinergic innervations with positron emission tomography (PET) would be a useful tool in understanding these diseases. A ligand for the vesicular acetylcholine transporter (VAChT), acknowledged as a marker for cholinergic neurons, could serve as such a PET tracer. The aim was to find a VAChT PET tracer using a library concept to create a small but diverse library of labeled compounds. From the same precursor and commercially available aryl iodides 6a-f, six potential VAChT PET tracers, [C-11]-(+/-)5a-f, were C-11-labeled by a palladium (0)-mediated aminocarbonylation, utilizing a standard protocol. The labeled compounds [C-11]-(+/-)5a-f were obtained in radiochemical purities >95% with decay-corrected radiochemical yields and specific radioactivities between 4-25% and 124-597 GBq/mu mol, respectively. Autoradiography studies were then conducted to assess the compounds binding selectivity for VAChT. Labeled compounds [C-11]-(+/-)5d and [C-11]-(+/-)5e showed specific binding but not enough to permit further preclinical studies. To conclude, a general method for a facile synthesis and labeling of a small piperazine-based library of potential PET tracers for imaging of VAChT was shown, and in upcoming work, another scaffold will be explored using this approach.

  • 9.
    Bergstrand, Nill
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Bohl, Erika
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för onkologi, radiologi och klinisk immunologi, Enheten för biomedicinsk strålningsvetenskap.
    Carlsson, Jörgen
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för onkologi, radiologi och klinisk immunologi, Enheten för biomedicinsk strålningsvetenskap.
    Edwards, Katarina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Ghaneolhosseine, Hadi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Gedda, Lars
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för onkologi, radiologi och klinisk immunologi, Enheten för biomedicinsk strålningsvetenskap.
    Jonsson, Markus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Silvander, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Sjöberg, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Stabilised Liposomes with Double Targeting for Use in BNCT2000Ingår i: Contemporary Boron Chemistry / [ed] Matthew Davidson, Cambridge, UK: Royal Society of Chemistry, 2000, s. 131-134Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 10.
    Biswas, Srijit
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Syntetisk organisk kemi.
    Dahlstrand, Christian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Watile, Rahul A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Syntetisk organisk kemi.
    Kalek, Marcin
    Himo, Fahmi
    Samec, Joseph S. M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Syntetisk organisk kemi.
    Atom-Efficient Gold(I)-Chloride-Catalyzed Synthesis of alpha-Sulfenylated Carbonyl Compounds from Propargylic Alcohols and Aryl Thiols: Substrate Scope and Experimental and Theoretical Mechanistic Investigation2013Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 19, nr 52, s. 17939-17950Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Gold(I)-chloride-catalyzed synthesis of -sulfenylated carbonyl compounds from propargylic alcohols and aryl thiols showed a wide substrate scope with respect to both propargylic alcohols and aryl thiols. Primary and secondary aromatic propargylic alcohols generated -sulfenylated aldehydes and ketones in 60-97% yield. Secondary aliphatic propargylic alcohols generated -sulfenylated ketones in yields of 47-71%. Different gold sources and ligand effects were studied, and it was shown that gold(I) chloride gave the highest product yields. Experimental and theoretical studies demonstrated that the reaction proceeds in two separate steps. A sulfenylated allylic alcohol, generated by initial regioselective attack of the aryl thiol on the triple bond of the propargylic alcohol, was isolated, evaluated, and found to be an intermediate in the reaction. Deuterium labeling experiments showed that the protons from the propargylic alcohol and aryl thiol were transferred to the 3-position, and that the hydride from the alcohol was transferred to the 2-position of the product. Density functional theory (DFT) calculations showed that the observed regioselectivity of the aryl thiol attack towards the 2-position of propargylic alcohol was determined by a low-energy, five-membered cyclic protodeauration transition state instead of the strained, four-membered cyclic transition state found for attack at the 3-position. Experimental data and DFT calculations supported that the second step of the reaction is initiated by protonation of the double bond of the sulfenylated allylic alcohol with a proton donor coordinated to gold(I) chloride. This in turn allows for a 1,2-hydride shift, generating the final product of the reaction.

  • 11.
    Blom, Elisabeth
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC.
    Velikyan, Irina
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för radiologi, onkologi och strålningsvetenskap, Enheten för biomedicinsk strålningsvetenskap. Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för radiologi, onkologi och strålningsvetenskap, Enheten för nuklearmedicin och PET.
    Estrada, Sergio
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Plattformen för preklinisk PET.
    Hall, Håkan
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Plattformen för preklinisk PET.
    Muhammad, Taj
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för radiologi, onkologi och strålningsvetenskap.
    Ding, Chenmin
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för radiologi, onkologi och strålningsvetenskap.
    Nair, Manoj
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för radiologi, onkologi och strålningsvetenskap.
    Långström, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Ga-68-Labeling of RGD peptides and biodistribution2012Ingår i: International Journal of Clinical and Experimental Medicine, ISSN 1940-5901, E-ISSN 1940-5901, Vol. 5, nr 2, s. 165-172Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Several peptides comprising Arg-Gly-Asp (RGD) domain and macrocyclic chelator were labeled with Ga-68 for the imaging of angiogenesis. The analogues varied in peptide constitution, linker and chelator type. The labeling efficiency did not vary with the peptide constitution and linker type, but depended on the chelator type. Four of the compounds containing 2,2', 2 '', 2'''-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl) tetraacetic acid (DOTA) chelator were labeled at 90 +/- 5 degrees C using conventional or microwave heating reaching 90% of Ga-68 incorporation after 5 and 2 min respectively, when the concentration of the precursor was 2.5 mu M. The compound having 2,2', 2 ''-(1,4,7-triazonane1,4,7-triyl)triacetic acid (NOTA) as the chelator could be labeled at room temperature within 5 min using 2.5 mu M peptide precursor. Two of the compounds contained a poly (ethylene glycol) (PEG) linker to the chelator. The biodistribution of the analogues was studied in male rats.

  • 12.
    Blom, Hans
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Purification Processes for Complex Biomacromolecules2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis details various techniques and considerations for the purification of complex biomacromolecules.

     

    Initially an α-mannosidase from babaco fruit was purified using anion exchange-, lectin affinity- and size exclusion chromatography.  The enzyme was approximately 260-280 kDa in size with an apparent an unusual octagonal stoichiometry and displayed properties similar to other known plant α-mannosidases.

     

    Mucins were fractionated by ion exchange and size exclusion chromatography to assess the properties that govern the mucin surface coating interactions in biomaterial research.  Commercially available mucins, of bovine and porcine origin, as wells as crude human mucin were tested. All showed to consist of a population of molecules which differ in size, charge and composition.

     

    The third part of the thesis concerns different aspects of plasmid DNA purification processes.

    A two-step method for analysis of plasmid DNA consisting of size exclusion followed by thiophilic adsorption chromatography was evaluated. It allowed determination of the supercoiled plasmid DNA concentration in all process steps without requirement for extensive sample preparation. This method was shown to be fully comparable in terms of accuracy to capillary gel electrophoresis, considered as the industry standard.

    Purification of plasmid DNA generally involves bacterial cell alkaline lysis, which creates a solution with flocculate material which needs to be removed prior to further processing. The addition of ammonium hydrogen carbonate to the suspension was evaluated to clarify the solution. The released carbon dioxide and ammonium lifts the flocculate to the surface and allows draining of a clear solution. The method is fully scalable, does not affect the plasmid DNA quality and requires no special equipment.

    Thiophilic adsorption chromatography was evaluated for simplification of an existing commercial large scale purification process and was shown to increase both product purity and yields of several tested plasmids. Also, implementation of this step significantly reduced overall production process time.

     

     

     

    Delarbeten
    1. Purification and Characterization of an alpha-Mannosidase from the Tropical Fruit Babaco (Vasconcellea x Heilbornii Cv. Babaco)
    Öppna denna publikation i ny flik eller fönster >>Purification and Characterization of an alpha-Mannosidase from the Tropical Fruit Babaco (Vasconcellea x Heilbornii Cv. Babaco)
    2008 (Engelska)Ingår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 56, nr 22, s. 10872-10878Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    An alpha-mannosidase (EC 3.2.1.24) present in the lyophilized latex of babaco (Vasconcellea heilbornii) has been purified to apparent homogeneity by native PAGE. The purification involves a three-step procedure with successive anion exchange with 0 Sepharose HP, lectin affinity chromatography using ConA Sepharose 4B, and gel filtration using Superdex 200 prep grade. The molecular mass was determined to be in the range of 260-280 kDa by Superdex 200 prep grade gel filtration, and isoelectric focusing showed a pI range between 5.85 and 6.55, suggesting different glycosylated isoforms. The optimal temperature for the alpha-mannosidase was determined to lie between 50 and 60 degrees C, and the optimal pH was 4.5 at 50 degrees C. The K-m value for p-nitrophenyl alpha-mannopyranoside (pNPM) was found to be 1.25 mM and the V-max, 2.4 mu kat mg(-1) at 50 degrees C and 1.94 mu kat mg(-1) at 40 degrees C. The pure alpha-mannosidase was specific for mannose and did not display activity for any other tested synthetic substrates.

    Nyckelord
    alpha-Mannosidase, babaco, latex, purification, characterization, subunit composition
    Nationell ämneskategori
    Kemi
    Identifikatorer
    urn:nbn:se:uu:diva-107031 (URN)10.1021/jf800857k (DOI)000261056700065 ()
    Tillgänglig från: 2009-07-15 Skapad: 2009-07-15 Senast uppdaterad: 2017-12-13Bibliografiskt granskad
    2. Potential use of mucins as biomaterial coatings. I. Fractionation, characterization, and model adsorption of bovine, porcine, and human mucins
    Öppna denna publikation i ny flik eller fönster >>Potential use of mucins as biomaterial coatings. I. Fractionation, characterization, and model adsorption of bovine, porcine, and human mucins
    2009 (Engelska)Ingår i: Journal of Biomedical Materials Research Part A, ISSN (printed): 1549-3296. (electronic): 1552-4965., Vol. 91A, nr 3, s. 762-772Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Previously, we presented evidence that mucins have potential as   biomaterial coatings. Here, we reveal substantial batch-to-batch   variations for a frequently used commercial bovine salivary mucin   preparation (BSM) and stress the importance of standardizing mucins   intended for comparative purposes. "Mild" fractionation strategies,   aiming at preserving natural mucin functions, were used to prepare two   more defined BSM fractions as well as three mucin fractions from   porcine gastric (PGM) and human salivary (MG1) sources. While the BSM   and PGM were highly purified and mainly adopted random coil   conformations in solution, the MG1 contained mucin-bound components   (1.6 wt% albumin) and appeared compact. Average molar masses and   root-mean-square radii for the predominant BSM, PGM, and MG1 species   spanned 0.8-4.2 MDa and 46-86 nm, respectively. An ellipsometric   evaluation, using hydrophilic and hydrophobic silica, showed the mucin   adsorption to be slow and related to mucin charge, size, conformation,   and compositional complexity. The mass uptakes on hydrophobic silica   averaged 2.6, 2.6, and 5.0 mg/m(2), for BSM, PGM, and MG1,   respectively. Finally, we find that stable mucin coatings can be formed   on polymers of different wettability. The reported mucin preparations   serve as platforms for a series of studies on the biocompatibility of  mucin coatings.

    Nyckelord
    mucin fractionation, mucin-associated components, size-exclusion chromatograpliy-multiangle light scattering-refractometry (SEC-MALS-RI), biomaterial coating, MUC5B
    Nationell ämneskategori
    Kemi
    Identifikatorer
    urn:nbn:se:uu:diva-97899 (URN)10.1002/jbm.a.32266 (DOI)000271588800014 ()19051309 (PubMedID)
    Tillgänglig från: 2008-11-28 Skapad: 2008-11-28 Senast uppdaterad: 2012-08-01Bibliografiskt granskad
    3. A chromatographic method for determination of supercoiled plasmid DNA concentration in complex solutions.
    Öppna denna publikation i ny flik eller fönster >>A chromatographic method for determination of supercoiled plasmid DNA concentration in complex solutions.
    2009 (Engelska)Ingår i: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 877, nr 24, s. 2530-6Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    A method for determination of the plasmid DNA concentration with subsequent analysis of the ratio supercoiled to open circular form is presented. The method is suitable for samples from all steps of the manufacturing process, from fermentation to final product. The analysis consists of size exclusion chromatography, followed by analytical thiophilic aromatic chromatography. In the first step, the plasmid DNA concentration is determined by group separation, including removal of RNA and other impurities, within less than 2 min. The limit of detection and quantification was 0.28 and 0.83 microg/ml, respectively. The precision of the method is high, providing a coefficient of variation as low as below 2%. In the second step, the ratio of open circular to supercoiled plasmid DNA is determined following separation of the two plasmid DNA isoforms with a linear salt gradient. The precision of the second step was evaluated using serial injections of aliquots of a sample stock solution. In comparison with the two most commonly used methods, the developed analysis was found to be significantly more accurate than agarose gel electrophoresis and equivalent to capillary gel electrophoresis. The combined methods for quantification and control of homogeneity of plasmid DNA presented here enable reliable and precise analysis at all steps of the manufacturing process.

    Nyckelord
    Concentration determination, Supercoiled plasmid DNA, Analytical group separation, Thiophilic aromatic chromatography
    Nationell ämneskategori
    Kemi
    Forskningsämne
    Kemi med inriktning mot ytbioteknik
    Identifikatorer
    urn:nbn:se:uu:diva-172792 (URN)10.1016/j.jchromb.2009.06.037 (DOI)19616488 (PubMedID)
    Tillgänglig från: 2012-04-16 Skapad: 2012-04-16 Senast uppdaterad: 2017-12-07
    4. Flocculate removal after alkaline lysis in plasmid DNA production.
    Öppna denna publikation i ny flik eller fönster >>Flocculate removal after alkaline lysis in plasmid DNA production.
    2010 (Engelska)Ingår i: Vaccine, ISSN 0264-410X, E-ISSN 1873-2518, Vol. 29, nr 1, s. 6-10Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Alkaline lysis is the most commonly used method following harvest of bacterial cells for production of plasmid DNA. The method was originally developed for laboratory scale experiments and has shown to be challenging at larger scales. A major problem prior to further downstream processing is the risk of filter clogging without efficient removal of the flocculate that occurs after neutralization. For this purpose we here present a scalable method where the clarification of alkaline lysate is greatly simplified. Through a rapid procedure, involving the addition of ammonium hydrogen carbonate to the neutralized alkaline lysate, the flocculate is lifted to the surface of the solution by the released carbon dioxide and ammonium. After this step a clarified solution can be drained from the bottom of the vessel. The procedure does not impact pH, plasmid DNA concentration or the ratio of open circular to supercoiled plasmid DNA in the solution.

    Nyckelord
    Alkaline lysis, Plasmid DNA, Flocculate removal
    Nationell ämneskategori
    Kemi
    Identifikatorer
    urn:nbn:se:uu:diva-172791 (URN)10.1016/j.vaccine.2010.10.021 (DOI)20974301 (PubMedID)
    Tillgänglig från: 2012-04-16 Skapad: 2012-04-16 Senast uppdaterad: 2017-12-07
    5. Scale Up of a Plasmid DNA Purification Process: Use of a Commercial Resin to Produce GMP-Grade pDNA for Clinical Studies
    Öppna denna publikation i ny flik eller fönster >>Scale Up of a Plasmid DNA Purification Process: Use of a Commercial Resin to Produce GMP-Grade pDNA for Clinical Studies
    Visa övriga...
    2010 (Engelska)Ingår i: BioProcess International, ISSN 1542-6319, Vol. 8, nr 11, s. 46-54Artikel i tidskrift (Refereegranskat) Published
    Nyckelord
    Chromatography, plasmid DNA
    Nationell ämneskategori
    Kemi
    Forskningsämne
    Kemi med inriktning mot ytbioteknik
    Identifikatorer
    urn:nbn:se:uu:diva-172889 (URN)
    Tillgänglig från: 2012-04-17 Skapad: 2012-04-17 Senast uppdaterad: 2012-08-01Bibliografiskt granskad
  • 13.
    Blom, Magnus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Syntetisk organisk kemi.
    Norrehed, Sara
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Syntetisk organisk kemi.
    Andersson, Claes-Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Syntetisk organisk kemi.
    Huang, Hao
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Light, Mark E.
    Department of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K.
    Bergquist, Jonas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Analytisk kemi.
    Grennberg, Helena
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Gogoll, Adolf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Syntetisk organisk kemi.
    Synthesis and Properties of Bis-Porphyrin Molecular Tweezers: Effects of Spacer Flexibility on Binding and Supramolecular Chirogenesis2016Ingår i: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 21, nr 1Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Abstract: Ditopic binding of various dinitrogen compounds to three bisporphyrin molecular tweezers with spacers of varying conformational rigidity, incorporating the planar ene-diyne (1), the helical stiff stilbene (2), or the semirigid glycoluril motif fused to  the porphyrins (3) are compared. Binding constants Ka = 10^4 to 10^6 M^-1 reveal subtle  differences between these tweezers, that are discussed in terms of porphyrin dislocation  modes. Exciton coupled circular dichroism (ECCD) of complexes with chiral dinitrogen  guests provides experimental evidence for the conformational properties of the tweezers. The results are further supported and rationalized by conformational analysis.

  • 14.
    Blom, Magnus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Syntetisk organisk kemi.
    Olsson, Sandra
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Syntetisk organisk kemi.
    Norrehed, Sara
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Syntetisk organisk kemi.
    Andersson, Claes-Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Grennberg, Helena
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Gogoll, Adolf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för biokemi och organisk kemi, Organisk kemi I.
    Photomodulable bis-porphyrin molecular tweezers as dynamic host systems for diamine guestsManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Bisporphyrin molecular tweezers with an enediyne (1) or a stiff stilbene (2) photoswitchable spacer are proposed as systems for modulation of bitopic binding to diamine guests via E/Z photoisomerization. The photoisomerization has been monitored by UV-Vis and 1H NMR spectroscopy and occurs without side reactions such as Bergman cyclization. Possible applications are rationalized in terms of competitive binding involving monoamine/diamine mixtures, and are supported by conformational analysis of the envisioned host-guest complexes. Binding dynamics for conformationally flexible guests show significantly different performance of aliphatic 1,w-diamine guests with varying N-N distance.

  • 15. Carter, Stephen F.
    et al.
    Scholl, Michael
    Almkvist, Ove
    Wall, Anders
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för radiologi, onkologi och strålningsvetenskap.
    Engler, Henry
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinska vetenskaper, Klinisk fysiologi.
    Långström, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Nordberg, Agneta
    Evidence for Astrocytosis in Prodromal Alzheimer Disease Provided by (11)C-Deuterium-L-Deprenyl: A Multitracer PET Paradigm Combining (11)C-Pittsburgh Compound B and (18)F-FDG2012Ingår i: Journal of Nuclear Medicine, ISSN 0161-5505, E-ISSN 1535-5667, Vol. 53, nr 1, s. 37-46Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Astrocytes colocalize with fibrillar amyloid-beta (A beta) plaques in postmortem Alzheimer disease (AD) brain tissue. It is therefore of great interest to develop a PET tracer for visualizing astrocytes in vivo, enabling the study of the regional distribution of both astrocytes and fibrillar A beta. A multitracer PET investigation was conducted for patients with mild cognitive impairment (MCI), patients with mild AD, and healthy controls using (11)C-deuterium-L-deprenyl ((11)C-DED) to measure monoamine oxidase B located in astrocytes. Along with (11)C-DED PET, (11)C-Pittsburgh compound B ((11)C-PIB; fibrillar A beta deposition), (18)F-FDG (glucose metabolism), T1 MRI, cerebrospinal fluid, and neuropsychologic data were acquired from the patients. Methods: (11)C-DED PET was performed in MCI patients (n = 8; mean age 6 SD, 62.6 +/- 7.5 y; mean Mini Mental State Examination, 27.5 +/- 2.1), AD patients (n = 7; mean age, 65.1 +/- 6.3 y; mean Mini Mental State Examination, 24.4 +/- 5.7), and healthy age-matched controls (n = 14; mean age, 64.7 +/- 3.6 y). A modified reference Patlak model, with cerebellar gray matter as a reference, was chosen for kinetic analysis of the (11)C-DED data. (11)C-DED data from 20 to 60 min were analyzed using a digital brain atlas. Mean regional (18)F-FDG uptake and (11)C-PIB retention were calculated for each patient, with cerebellar gray matter as a reference. Results: ANOVA analysis of the regional (11)C-DED binding data revealed a significant group effect in the bilateral frontal and bilateral parietal cortices related to increased binding in the MCI patients. All patients, except 3 with MCI, showed high (11)C-PIB retention. Increased (11)C-DED binding in most cortical and subcortical regions was observed in MCI (11)C-PIB+ patients relative to controls, MCI (11)C-PIB (negative) patients, and AD patients. No regional correlations were found between the 3 PET tracers. Conclusion: Increased (11)C-DED binding throughout the brain of the MCI (11)C-PIB+ patients potentially suggests that astrocytosis is an early phenomenon in AD development.

  • 16. Chavan, Swapnil
    et al.
    Friedman, Ran
    Nicholls, Ian A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Acute Toxicity-Supported Chronic Toxicity Prediction: A k-Nearest Neighbor Coupled Read-Across Strategy2015Ingår i: International Journal of Molecular Sciences, ISSN 1422-0067, E-ISSN 1422-0067, Vol. 16, nr 5, s. 11659-11677Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A k-nearest neighbor (k-NN) classification model was constructed for 118 RDT NEDO (Repeated Dose Toxicity New Energy and industrial technology Development Organization; currently known as the Hazard Evaluation Support System (HESS)) database chemicals, employing two acute toxicity (LD50)-based classes as a response and using a series of eight PaDEL software-derived fingerprints as predictor variables. A model developed using Estate type fingerprints correctly predicted the LD50 classes for 70 of 94 training set chemicals and 19 of 24 test set chemicals. An individual category was formed for each of the chemicals by extracting its corresponding k-analogs that were identified by k-NN classification. These categories were used to perform the read-across study for prediction of the chronic toxicity, i.e., Lowest Observed Effect Levels (LOEL). We have successfully predicted the LOELs of 54 of 70 training set chemicals (77%) and 14 of 19 test set chemicals (74%) to within an order of magnitude from their experimental LOEL values. Given the success thus far, we conclude that if the k-NN model predicts LD50 classes correctly for a certain chemical, then the k-analogs of such a chemical can be successfully used for data gap filling for the LOEL. This model should support the in silico prediction of repeated dose toxicity.

  • 17. Czyzewski, Michal
    et al.
    Sellars, Jonathan D.
    Guliashvili, Tamaz
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Tibbelin, Julius
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Johnstone, Lisa
    Bower, Justin
    Box, Matthew
    Davies, Robert D. M.
    Ottosson, Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Steel, Patrick G.
    The first intramolecular silene Diels-Alder reactions2014Ingår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 50, nr 22, s. 2919-2921Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The synthesis of silaheterocycles through the first examples of an intramolecular silene Diels-Alder reaction is described.

  • 18.
    Dahlstrand, Christian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Ground and Excited State Aromaticity: Design Tools for π-Conjugated Functional Molecules and Materials2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The main focus of this thesis is on the aromaticity of the ground state and electronically excited states of π-conjugated molecules and polymers, as well as how aromaticity is connected to their properties.

    The electronic structures of polybenzenoid hydrocarbons (PBHs) were explored through density functional theory (DFT) calculations and the π-component of the electron localization function (ELFπ). The study revealed how the π-electronic structure is influenced by the fusion of double bonds or benzene rings to the PBHs. We also demonstrated that the π-electrons of benzene extend to accommodate as much aromaticity as possible when bond length distorted.  

    The aromatic chameleon property displayed by fulvenes, isobenzofulvenes, fulvalenes, bis(fulvene)s, and polyfulvenes were investigated using DFT calculations. The tria-, penta-, and heptafulvenes were shown to possess ionization energies and electron affinities which can be tuned extensively by substitution, some of which even outperform TTF and TCNQ, the prototypical electron donor and acceptor, respectively. The singlet-triplet energy gap of pentafulvenes can be tuned extensively by substitution to the point that the triplet state is lower than the singlet state and thus becomes the ground state. The ELFπ of isobenzofulvene shows that the benzene ring in an electronically excited state can be more aromatic than the corresponding ring in the ground state. We have shown that the 6-ring of [5.6.7]quinarene is influenced by a Hückel aromatic resonance structure with 4n+2 π-electrons in the excited quintet state. The bis(fulvene)s which are composed of a donor type heptafulvene and an acceptor type pentafulvene, retain the basic donor-acceptor properties of the two fragments and could function as compact donor-acceptor dyads. A few of the designed polyfulvenes were found to have band gaps below 1 eV at the PBC-B3LYP/6-31G(d) level.

    Various 2,7-disubstituted fluorenones and dibenzofulvenes were synthesized and their excited state properties were investigated by absorption spectroscopy and time-dependent DFT calculations. It was found that the 1A1B transition of ππ* character can be tuned by substitution in the 2,7-positions. The 2,7-bis(N,N-dimethyl) derivatives of fluorenone and dibenzofulvene displayed low energy transitions at 2.18 and 1.61 eV, respectively, in toluene.

    Delarbeten
    1. On the Importance of Clar Structures of Polybenzenoid Hydrocarbons as Revealed by the n-Contribution to the Electron Localization Function
    Öppna denna publikation i ny flik eller fönster >>On the Importance of Clar Structures of Polybenzenoid Hydrocarbons as Revealed by the n-Contribution to the Electron Localization Function
    Visa övriga...
    2010 (Engelska)Ingår i: Symmetry, ISSN 2073-8994, E-ISSN 2073-8994, Vol. 2, nr 3, s. 1653-1682Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The degree of p-electron (de)localization and aromaticity of a series of polybenzenoid hydrocarbons (PBHs) has been analyzed through the π-contribution to the electron localization function (ELFπ), calculated at the B3LYP/6-311G(d,p) hybrid density functional theory level. The extent of p-electron delocalization in the various hexagons of a PBH was determined through analysis of the bifurcation values of the ELFp basins (BV(ELFp)), the spans in the bifurcation values in each hexagon (ΔBV(ELFπ)), and the ring-closure bifurcation values of the ELFπ (RCBV(ELFπ)). These computed results were compared to the qualitative description of local aromaticities of the different hexagons in terms of Clar structures with p-sextets. Benzene, [18]annulene, and thirty two PBHs were analyzed at their equilibrium geometries, and benzene and triphenylene were also analyzed at bond length distorted structures. In general, the description of PBHs in terms of Clar valence structures is supported by the ELFp properties, although there are exceptions. For PBHs at their equilibrium geometries there is a clear sigmoidal relationship between the CC bond lengths and the amount of p-electron (de)localization at these bonds, however, this relationship is lost for bond distorted geometries. In the latter cases, we specifically examined benzene in D3h symmetric “1,3,5-cyclohexatriene” structures and triphenylene in eight different structures. From the distorted benzenes and triphenylenes it becomes clear that there is a distinct tendency for the p-electron network to retain delocalization (aromaticity). The ELFp analysis thus reveals an antidistortive rather than a distortive behavior of the p-electrons in these investigated compounds.

    Ort, förlag, år, upplaga, sidor
    Basel: MDPI, 2010
    Nyckelord
    Clar structures, electron localization function, polybenzenoid hydrocarbons
    Nationell ämneskategori
    Annan medicinsk grundvetenskap
    Forskningsämne
    Kemi med inriktning mot organisk kemi; Kemi med inriktning mot kvantkemi
    Identifikatorer
    urn:nbn:se:uu:diva-140983 (URN)10.3390/sym2031653 (DOI)000208831900018 ()
    Tillgänglig från: 2011-01-10 Skapad: 2011-01-10 Senast uppdaterad: 2018-01-12Bibliografiskt granskad
    2. Substituent Effects on the Electron Affinities and Ionization Energies of Tria-, Penta-, and Heptafulvenes: A Computational Investigation
    Öppna denna publikation i ny flik eller fönster >>Substituent Effects on the Electron Affinities and Ionization Energies of Tria-, Penta-, and Heptafulvenes: A Computational Investigation
    2010 (Engelska)Ingår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 75, nr 23, s. 8060-8068Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The extent of substituent influence on the vertical electron affinities (EAs) and ionization energies (IEs) of 43 substituted tria-, penta-, and heptafulvenes was examined computationally at the OVGF/6-311G(d)//B3LYP/6-311G(d) level of theory and compared with those of tetracyanoquinodimethane (TCNQ) and tetrathiafulvalene (TTF) as representing strong electron-acceptor and -donor compounds, respectively. The substituents X at the exocyclic positions of the fulvenes were either NH2, H, or CN, while the substituents Y at the ring positions were H, CI, F, CN, or NH2. The variations of the EAs and lEs were rationalized by qualitative arguments based on frontier orbital symmetries for the different fulvene classes with either X or Y being constant. The minimum and maximum values found for the calculated EAs of the tria-, penta-, and heptafulvenes were 0.51-2.05, 0.24-3.63, and 0.53-3.14 eV, respectively, and for the IEs 5.27-9.96, 7.07-10.31, and 6.35-10.59 eV, respectively. Two of the investigated fulvenes outperform TCNQ (calcd EA = 2.63 eV) and one outperforms TTF (calcd IE = 6.25 eV) with regard to acceptor and donor abilities, respectively. We also evaluated the properties of bis(fulvene)s, i.e., compounds composed of a donor-type heptafulvene fused with an acceptor-type pentafulvene, and it was revealed that these bis(fulvene)s can be designed so that the IE and EA of the two separate fulvene segments are retained, potentially allowing for the design of compact donor-acceptor dyads.

    Nationell ämneskategori
    Kemi
    Identifikatorer
    urn:nbn:se:uu:diva-140156 (URN)10.1021/jo101634v (DOI)000284519900008 ()21067236 (PubMedID)
    Tillgänglig från: 2011-01-04 Skapad: 2011-01-04 Senast uppdaterad: 2017-12-11Bibliografiskt granskad
    3. Fulvenes: Compounds for which the Singlet-Triplet Energy Gaps are Closely Linked to Aromaticity and  Aromaticity Differences
    Öppna denna publikation i ny flik eller fönster >>Fulvenes: Compounds for which the Singlet-Triplet Energy Gaps are Closely Linked to Aromaticity and  Aromaticity Differences
    Visa övriga...
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Nationell ämneskategori
    Organisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-172869 (URN)
    Tillgänglig från: 2012-04-16 Skapad: 2012-04-16 Senast uppdaterad: 2012-08-01
    4. Exploration of the π-Electronic Structure of Singlet, Triplet, and Quintet States of Fulvenes and Fulvalenes Using the Electron Localization Function
    Öppna denna publikation i ny flik eller fönster >>Exploration of the π-Electronic Structure of Singlet, Triplet, and Quintet States of Fulvenes and Fulvalenes Using the Electron Localization Function
    2012 (Engelska)Ingår i: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 116, nr 20, s. 5008-5017Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The singlet ground states and lowest triplet states of penta- and heptafulvene, their benzannulated derivatives, as well as the lowest quintet states of pentaheptafulvalenes, either the parent compound or compounds in which the two rings are intercepted by either an alkynyl or a phenyl segment, were investigated at the (U)OLYP/6-311G(d,p) density functional theory level. The influence of (anti)-aromaticity was analyzed by the structure-based aromaticity index HOMA, the harmonic oscillator model of aromaticity. The extent of (anti)aromatic character was also evaluated in terms of the pi-electron (de)localization as measured by the pi component of the electron localization function (ELF pi). The natural atomic orbital (NAO) occupancies were calculated in order to evaluate the degree of pi-electron shift caused by the opposing electron-counting rules for aromaticity in the electronic ground state (S-0; Hiickel's rule) and the first pi pi* excited triplet state (T-1; Baird's rule). Pentaheptafulvalene (5) shows a shift of 0.5 pi electrons from the 5-ring to the 7-ring when going from the S-0 state to the lowest quintet state (Qu(1)). The pentaheptafulvalene 5 and [5.6.7]quinarene 7 were also investigated in their 90 degrees twisted conformations. From our study it is apparent that excitation localization in fulvalenes, but not in fulvenes, to a substantial degree is determined by aromaticity localization to triplet biradical 4n pi-electron cycles. Isolated benzene rings in these compounds tend to remain as closed-shell 6 pi-electron cycles.

    Nationell ämneskategori
    Organisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-172377 (URN)10.1021/jp3032397 (DOI)000304338600021 ()
    Tillgänglig från: 2012-04-09 Skapad: 2012-04-09 Senast uppdaterad: 2017-12-07Bibliografiskt granskad
    5. Manipulation of Excited State Energies in Fulvenic Molecules
    Öppna denna publikation i ny flik eller fönster >>Manipulation of Excited State Energies in Fulvenic Molecules
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Nationell ämneskategori
    Organisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-172871 (URN)
    Tillgänglig från: 2012-04-16 Skapad: 2012-04-16 Senast uppdaterad: 2012-08-01
    6. Tuning the Band Gap of Polyfulvenes by Use of “Handles”: On the Effects of Exocyclic Substitution, Benzannulation, and Ring Methylation.
    Öppna denna publikation i ny flik eller fönster >>Tuning the Band Gap of Polyfulvenes by Use of “Handles”: On the Effects of Exocyclic Substitution, Benzannulation, and Ring Methylation.
    Visa övriga...
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Nationell ämneskategori
    Polymerkemi Teoretisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-172872 (URN)
    Tillgänglig från: 2012-04-16 Skapad: 2012-04-16 Senast uppdaterad: 2012-08-01
  • 19.
    Dahlstrand, Christian
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Jahn, Burkhard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC.
    Grigoriev, Anton
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Villaume, Sebastien
    Ahuja, Rajeev
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Ottosson, Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Tuning the Band Gap of Polyfulvenes by Use of “Handles”: On the Effects of Exocyclic Substitution, Benzannulation, and Ring Methylation.Manuskript (preprint) (Övrigt vetenskapligt)
  • 20.
    Dahlstrand, Christian
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Rosenberg, Martin
    Department of Chemistry, University of Copenhagen.
    Kilså, Kristine
    Department of Chemistry, University of Copenhagen.
    Ottosson, Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Exploration of the π-Electronic Structure of Singlet, Triplet, and Quintet States of Fulvenes and Fulvalenes Using the Electron Localization Function2012Ingår i: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 116, nr 20, s. 5008-5017Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The singlet ground states and lowest triplet states of penta- and heptafulvene, their benzannulated derivatives, as well as the lowest quintet states of pentaheptafulvalenes, either the parent compound or compounds in which the two rings are intercepted by either an alkynyl or a phenyl segment, were investigated at the (U)OLYP/6-311G(d,p) density functional theory level. The influence of (anti)-aromaticity was analyzed by the structure-based aromaticity index HOMA, the harmonic oscillator model of aromaticity. The extent of (anti)aromatic character was also evaluated in terms of the pi-electron (de)localization as measured by the pi component of the electron localization function (ELF pi). The natural atomic orbital (NAO) occupancies were calculated in order to evaluate the degree of pi-electron shift caused by the opposing electron-counting rules for aromaticity in the electronic ground state (S-0; Hiickel's rule) and the first pi pi* excited triplet state (T-1; Baird's rule). Pentaheptafulvalene (5) shows a shift of 0.5 pi electrons from the 5-ring to the 7-ring when going from the S-0 state to the lowest quintet state (Qu(1)). The pentaheptafulvalene 5 and [5.6.7]quinarene 7 were also investigated in their 90 degrees twisted conformations. From our study it is apparent that excitation localization in fulvalenes, but not in fulvenes, to a substantial degree is determined by aromaticity localization to triplet biradical 4n pi-electron cycles. Isolated benzene rings in these compounds tend to remain as closed-shell 6 pi-electron cycles.

  • 21. Darreh-Shori, Taher
    et al.
    Vijayaraghavan, Swetha
    Aeinehband, Shahin
    Piehl, Fredrik
    Lindblom, Rickard P F
    Uppsala universitet, Medicinsk