kth.sePublications
Change search
Refine search result
123 1 - 50 of 148
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1. Andrae, Johan C. G.
    et al.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Kalghatgi, G. T.
    HCCI experiments with toluene reference fuels modeled by a semidetailed chemical kinetic model2008In: Combustion and Flame, ISSN 0010-2180, E-ISSN 1556-2921, Vol. 155, no 4, p. 696-712Article in journal (Refereed)
    Abstract [en]

    A semidetailed mechanism (137 species and 633 reactions) and new experiments in a homogeneous charge conic pression ignition (HCCI) engine on the autoignition of toluene reference fuels are presented. Skeletal mechanisms for isooctane and n-heptane were added to a detailed toluene submechanism. The model shows generally good agreement with ignition delay times measured in a shock tube and a rapid compression machine and is sensitive to changes in temperature, pressure, and mixture strength. The addition of reactions involving the formation and destruction of benzylperoxide radical was crucial to modeling toluene shock tube data. Laminar burning velocities for benzene and toluene were well predicted by the model after some revision of the high-temperature chemistry. Moreover, laminar burning velocities of a real gasoline at 353 and 500 K Could be predicted by the model using a toluene reference fuel as a surrogate. The model also captures the experimentally observed differences in combustion phasing of toluene/n-heptane mixtures, compared to a primary reference fuel of the same research octane number, in HCCI engines as the intake pressure and temperature are changed. For high intake pressures and low intake temperatures, a sensitivity analysis at the moment of maximum heat release rate shows that the consumption of phenoxy radicals is rate-limiting when a toluene/n-heptane fuel is used, which makes this fuel more resistant to autoignition than the primary reference fuel. Typical CPU times encountered in zero-dimensional calculations were on the order of seconds and minutes in laminar flame speed calculations. Cross reactions between benzylperoxy radicals and n-heptane improved the model prediction,,; of shock tube experiments for phi = 1.0 and temperatures lower than 800 K for an n-heptane/toluene fuel mixture, but cross reactions had no influence on HCCI Simulations.

  • 2.
    Angelin, Marcus
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Rahm, Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Fischer, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Diastereoselective One-Pot Tandem Synthesis of 3-Substituted Isoindolinones: A Mechanistic Investigation2010In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 75, no 17, p. 5882-5887Article in journal (Refereed)
    Abstract [en]

    The mechanism of a base-catalyzed one-pot reaction of 2-cyanobenzaldehyde and primary nitroalkanes, to produce 3-substituted isoindolinones, has been investigated. A route starting with a nitroaldol (Henry) reaction, followed by a subsequent cyclization and rearrangement, was supported by intermediate analogue synthesis and DFT calculations. Direct diastereoselective crystallization from the reaction mixture was also achieved and studied for a number of substrates. Furthermore, the 3-substituted isoindolinones are an interesting group of compounds, both present important natural products, as well as being precursors to other valuable building blocks.

  • 3.
    Berglund, Per
    et al.
    KTH, Superseded Departments (pre-2005), Biotechnology.
    Branneby, Cecilia
    Svedendahl Humble, Maria
    KTH, School of Biotechnology (BIO), Biochemistry.
    Carlqvist, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Magnusson, Anders
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Aldol and Michael additions catalyzed by a rationally redesigned hydrolytic enzyme2003In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 226, no 2, p. U155-U156Article in journal (Refereed)
  • 4.
    Besharat, Zahra
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Material Physics, MF. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Halldin Stenlid, Joakim
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Soldemo, Markus
    KTH, School of Engineering Sciences (SCI), Applied Physics, Material Physics, MF.
    Marks, Kess
    Önsten, Anneli
    KTH, School of Engineering Sciences (SCI), Applied Physics, Material Physics, MF.
    Johnson, Magnus
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Öström, Henrik
    Weissenrieder, Jonas
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Göthelid, Mats
    KTH, School of Engineering Sciences (SCI), Applied Physics, Material Physics, MF.
    Dehydrogenation of methanol on Cu2O(100) and (111)2017In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 146, no 24Article in journal (Refereed)
    Abstract [en]

    Adsorption and desorption of methanol on the (111) and (100) surfaces of  Cu2O have been studied using high-resolution photoelectron spectroscopy in the temperature range 120–620 K, in combination with density functional theorycalculations and sum frequency generation spectroscopy. The bare (100) surfaceexhibits a (3,0; 1,1) reconstruction but restructures during the adsorption process into a Cu-dimer geometry stabilized by methoxy and hydrogen binding in Cu-bridge sites. During the restructuring process, oxygen atoms from the bulk that can host hydrogen appear on the surface. Heating transforms methoxy to formaldehyde, but further dehydrogenation is limited by the stability of the surface and the limited access to surface oxygen. The (√3 × √3)R30°-reconstructed (111) surface is based on ordered surface oxygen and copper ions and vacancies, which offers a palette of adsorption and reaction sites. Already at 140 K, a mixed layer of methoxy, formaldehyde, and CHxOy is formed. Heating to room temperature leaves OCH and CHx. Thus both CH-bond breaking and CO-scission are active on this  surface at low temperature. The higher ability to dehydrogenate methanol on (111) compared to (100) is explained by the multitude of adsorption sites and, in particular, the availability of surfaceoxygen.

  • 5. Bittererova, M.
    et al.
    Brinck, Tore
    KTH, Superseded Departments (pre-2005), Chemistry.
    Ostmark, H.
    Theoretical study of the singlet electronically excited states of N-42001In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 340, no 06-maj, p. 597-603Article in journal (Refereed)
    Abstract [en]

    Vertical excitation energies for the lowest eleven singlet states of T-d N-4 were calculated using the TD-DFT method with the B3LYP functional, and at the EOM-CCSD level of theory. The vertical excitation energies for the five lowest-lying excited states were also obtained using the state-averaged CASSCF, CASPT2, CASPT3, and MRCI + Q methods. Our results show that the five lowest-lying states are of valence character. EOM-CCSD/d-aug-cc-pVTZ calculations predict that there are two weakly allowed optical transitions of T-2 symmetry at 10.44 and 10.82 eV. The transition to the third T-2 state, which is predicted to be at 10.89 eV, has an oscillator strength about one order of magnitude higher.

  • 6. Bittererova, M.
    et al.
    Brinck, Tore
    KTH, Superseded Departments (pre-2005), Chemistry.
    Ostmark, H.
    Theoretical study of the triplet N-4 potential energy surface2000In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 104, no 51, p. 11999-12005Article in journal (Refereed)
    Abstract [en]

    The N-4 molecule in its triplet state has been studied using the DFT-B3LYP, CASSCF, and CCSD(T) computational methods. The previously reported C-s ((3)A ) minimum was not found to be stable using these methods. A D-2d ((3)A(1)) minimum was found to be the lowest energy triplet with a closed structure. This minimum is 20.2 kcal/mol higher in energy than T-d ((1)A(1)) N-4 at the CCSD(T)/cc-pVTZ//CCSD(T)/DZP level of theory. The barrier to dissociation has been estimated to ca. 7.5 kcal/mol from CAS(8,8)+MR-ACPF and CAS(8,8)+MR-AQCC calculations. CASSCF(12,12) calculations indicate that the open-chain N-4 Of C-2h (B-3(u)) symmetry is not stable. The open-chain C-s((3)A ) structure has been found to be a true minimum at all investigated levels of theory. It is 13.4 kcal/mol lower in energy than T-d ((1)A(1)) N-4 at the CCSD(T)/cc-pVTZ//CCSD(T)/DZP level.

  • 7. Bittererova, M.
    et al.
    Ostmark, H.
    Brinck, Tore
    KTH, Superseded Departments (pre-2005), Chemistry.
    A theoretical study of the azide (N-3) doublet states. A new route to tetraazatetrahedrane (N-4): N+N-3 -> N-42002In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 116, no 22, p. 9740-9748Article in journal (Refereed)
    Abstract [en]

    The potential energy surfaces for the low-lying doublet states of the azide radical (N-3) have been computed at the complete active space self-consistent field (CASSCF) level with the CAS(15,12) active space. The cc-pVTZ and aug-cc-pVTZ basis sets have been employed throughout the present work. Energies, geometries and harmonic frequencies were determined for the N-3 linear ground electronic state ((2)Pi(g)), a stable C-2v ring structure (B-2(1)), and a C-s transition state ((2)A(')) connecting the ring and linear structures. Other N-3 (C-2v) stationary points ((2)A(2), B-2(1), and (2)A(1)) have been characterized, as well. The vertical excitation energies for the doublet excited states of the N-3 linear ((2)Pi(g)) and stable ring (B-2(1)) isomers were calculated using CASSCF and multireference configuration interaction [MRCI-SD(Q)] methods. A new route to tetraazatetrahedrane [N-4(T-d)] has been proposed on the N-4 singlet potential energy surface within C-s symmetry. MRCI-SD(Q) calculations predict that N-4 (T-d) can be formed from atomic nitrogen in the D-2 state and N-3 (C-2v, B-2(1)) in a barrierless exothermic reaction. The energy difference (D-0) is 135.4 kcal/mol at the MRCI-SD(Q) level.

  • 8. Bittererova, M.
    et al.
    Ostmark, H.
    Brinck, Tore
    KTH, Superseded Departments (pre-2005), Chemistry.
    Ab initio study of the ground state and the first excited state of the rectangular (D-2h) N-4 molecule2001In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 347, no 03-jan, p. 220-228Article in journal (Refereed)
    Abstract [en]

    The dissociation pathway of D-2h N-4 has been investigated at the CASSCF level of theory. A new C-2v transition state to dissociation was found and characterized on the potential energy surface. The effective barrier of dissociation from D-2h N-4 to 2N(2) is estimated to 6.5 kcal/mol from MR-AQCCNTZ//CAS(12,12)/VTZ calculations. Vertical excitation energies and oscillator strengths for the lowest 20 singlet states of D-2h N-4 have been calculated using the EOM-CCSD method. The geometry of the first excited state B-1(3u), considered as the lowest optically accessible state, has been optimized and characterized at various computational levels. This state might be useful for detection of D-2h N-4 by means of laser-induced fluorescence (LIF) spectroscopy.

  • 9.
    Brandt, Erik G.
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics.
    Hellgren, Mikko
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Bergman, Tomas
    Edholm, Olle
    KTH, School of Engineering Sciences (SCI), Theoretical Physics.
    Molecular dynamics study of zinc binding to cysteines in a peptide mimic of the alcohol dehydrogenase structural zinc site2009In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 11, no 6, p. 975-983Article in journal (Refereed)
    Abstract [en]

    The binding of zinc (Zn) ions to proteins is important for many cellular events. The theoretical and computational description of this binding (as well as that of other transition metals) is a challenging task. In this paper the binding of the Zn ion to four cysteine residues in the structural site of horse liver alcohol dehydrogenase (HLADH) is studied using a synthetic peptide mimic of this site. The study includes experimental measurements of binding constants, classical free energy calculations from molecular dynamics (MD) simulations and quantum mechanical (QM) electron structure calculations. The classical MD results account for interactions at the molecular level and reproduce the absolute binding energy and the hydration free energy of the Zn ion with an accuracy of about 10%. This is insufficient to obtain correct free energy differences. QM correction terms were calculated from density functional theory (DFT) on small clusters of atoms to include electronic polarisation of the closest waters and covalent contributions to the Zn-S coordination bond. This results in reasonably good agreement with the experimentally measured binding constants and Zn ion hydration free energies in agreement with published experimental values. The study also includes the replacement of one cysteine residue to an alanine. Simulations as well as experiments showed only a small effect of this upon the binding free energy. A detailed analysis indicate that the sulfur is replaced by three water molecules, thereby changing the coordination number of Zn from four (as in the original peptide) to six (as in water).

  • 10.
    Branneby, Cecilia
    et al.
    KTH, Superseded Departments (pre-2005), Biotechnology.
    Carlqvist, Peter
    KTH, Superseded Departments (pre-2005), Chemistry.
    Hult, Karl
    KTH, Superseded Departments (pre-2005), Biotechnology.
    Brinck, Tore
    KTH, Superseded Departments (pre-2005), Chemistry.
    Berglund, Per
    KTH, Superseded Departments (pre-2005), Biotechnology.
    Aldol Additions with Mutant Lipase: Analysis by Experiments and Theoretical Calculations2004In: Journal of Molecular Catalysis B: Enzymatic, ISSN 1381-1177, E-ISSN 1873-3158, Vol. 31, no 4-6, p. 123-128Article in journal (Refereed)
    Abstract [en]

    A Ser105Ala mutant of Candida antarctica lipase B has previously been shown to catalyze aldol additions. Quantum chemical calculations predicted a reaction rate similar to that of natural enzymes, whereas experiments showed a much lower reaction rate. Molecular dynamics simulations, presented here, show that the low reaction rate is a consequence of the low frequencies of near attack complexes in the enzyme. Equilibrium was also considered as a reason for the slow product formation, but could be excluded by performing a sequential reaction to push the reaction towards product formation. In this paper, further experimental results are also presented, highlighting the importance of the entire active site for catalysis.

  • 11. Branneby, Cecilia
    et al.
    Carlqvist, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Berglund, Per
    KTH, Superseded Departments (pre-2005), Biotechnology.
    Rational redesign of a lipase to an aldolase2003In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 42, no 28, p. 8633-8633Article in journal (Refereed)
  • 12.
    Branneby, Cecilia
    et al.
    KTH, Superseded Departments (pre-2005), Biotechnology.
    Carlqvist, Peter
    KTH, Superseded Departments (pre-2005), Chemistry.
    Magnusson, Anders
    KTH, Superseded Departments (pre-2005), Biotechnology.
    Hult, Karl
    KTH, Superseded Departments (pre-2005), Biotechnology.
    Brinck, Tore
    KTH, Superseded Departments (pre-2005), Chemistry.
    Berglund, Per
    KTH, Superseded Departments (pre-2005), Biotechnology.
    Carbon-Carbon Bonds by Hydrolytic Enzymes2003In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 125, no 4, p. 874-875Article in journal (Refereed)
    Abstract [en]

    Enzymes are efficient catalysts in synthetic chemistry, and their catalytic activity with unnatural substrates in organic reaction media is an area attracting much attention. Protein engineering has opened the possibility to change the reaction specificity of enzymes and allow for new reactions to take place in their active sites. We have used this strategy on the well-studied active-site scaffold offered by the serine hydrolase Candida antarctica lipase B (CALB, EC 3.1.1.3) to achieve catalytic activity for aldol reactions. The catalytic reaction was studied in detail by means of quantum chemical calculations in model systems. The predictions from the quantum chemical calculations were then challenged by experiments. Consequently, Ser105 in CALB was targeted by site-directed mutagenesis to create enzyme variants lacking the nucleophilic feature of the active site. The experiments clearly showed an increased reaction rate when the aldol reaction was catalyzed by the mutant enzymes as compared to the wild-type lipase. We expect that the new catalytic activity, harbored in the stable protein scaffold of the lipase, will allow aldol additions of substrates, which cannot be reached by traditional aldolases

  • 13.
    BRINCK, T
    et al.
    University of New Orleans.
    MURRAY, JS
    POLITZER, P
    University of New Orleans.
    A COMPUTATIONAL ANALYSIS OF THE BONDING IN BORON-TRIFLUORIDE AND BORON-TRICHLORIDE AND THEIR COMPLEXES WITH AMMONIA1993In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 32, no 12, p. 2622-2625Article in journal (Refereed)
    Abstract [en]

    Complexation energies for the interactions of BF3 and BCl3 with NH3 have been calculated at the ab initio Hartree-Fock and MP2 levels of theory, using large polarized basis sets. The formation of H3N.BCl3 is found to be favored by 4.27 kcal/mol over H3N.BF3 at the MP2 level. This is in agreement with the experimental observation that the Lewis acidities of the boron trihalides increase in the order BF3 < BCl3 < BBr3. Calculated atomic charges and molecular electrostatic potentials show the boron to be much more positive in BF3 than in BCl3, as would be expected from the respective electronegativities of fluorine and chlorine. These results and the relevant ppi-ppi overlap integrals do not support using the concept of back-bonding and consequent stabilization to explain the trend in Lewis acidities. As an alternative explanation, it is suggested that this trend reflects the importance of Lewis base --> BX3 charge transfer in these complexes and the fact that the ability to accept the charge, as indicated by charge capacities, increases in the order BF3 < BCl3 < BBr3.

  • 14.
    BRINCK, T
    et al.
    University of New Orleans.
    MURRAY, JS
    POLITZER, P
    POLARIZABILITY AND VOLUME1993In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 98, no 5, p. 4305-4306Article in journal (Refereed)
  • 15.
    BRINCK, T
    et al.
    University of New Orleans.
    MURRAY, JS
    POLITZER, P
    QUANTITATIVE-DETERMINATION OF THE TOTAL LOCAL POLARITY (CHARGE SEPARATION) IN MOLECULES1992In: Molecular Physics, ISSN 0026-8976, E-ISSN 1362-3028, Vol. 76, no 3, p. 609-617Article in journal (Refereed)
    Abstract [en]

    We introduce a polarity index-PI that is proposed as a measure of the charge separation in a molecule. PI can be viewed as the average deviation of the electrostatic potential on the surface of the molecule. It permits a quantitative assessment of total local polarity, even in a molecule that has zero dipole moment. In support of our formulation of PI, we show that it is related to an empirical polarity-polarizability parameter and also to the dielectric constant.

  • 16.
    BRINCK, T
    et al.
    University of New Orleans.
    MURRAY, JS
    POLITZER, P
    RELATIONSHIPS BETWEEN THE AQUEOUS ACIDITIES OF SOME CARBON, OXYGEN, AND NITROGEN ACIDS AND THE CALCULATED SURFACE LOCAL IONIZATION ENERGIES OF THEIR CONJUGATE BASES1991In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 56, no 17, p. 5012-5015Article in journal (Refereed)
    Abstract [en]

    Average local ionization energies (IBAR(r)) have been computed on the molecular surfaces of the conjugate bases for four different groups of carbon and oxygen acids using an ab initio self-consistent-field molecular orbital approach. The lowest surface IBAR(r) (IBAR(S,min)) are generally found on the atom from which the proton has been abstracted. Good linear relationships between aqueous acidities and IBAR(S,min) are found for the different groups. A single linear relationship between pK(a) and IBAR(S,min) that includes the four groups and three additional nitrogen acids also exists; the correlation coefficient is 0.97. This provides a means for predicting the pK(a)'s of a large variety of carbon, oxygen, and nitrogen acids.

  • 17.
    BRINCK, T
    et al.
    University of New Orleans.
    MURRAY, JS
    POLITZER, P
    CARTER, RE
    A RELATIONSHIP BETWEEN EXPERIMENTALLY DETERMINED PKAS AND MOLECULAR-SURFACE IONIZATION ENERGIES FOR SOME AZINES AND AZOLES1991In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 56, no 8, p. 2934-2936Article in journal (Refereed)
  • 18.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Green Energetic Materials2014Collection (editor) (Other academic)
    Abstract [en]

    Since the end of the 20th century it has been increasingly realised that the use, or production, of many energetic materials leads to the release of substances which are harmful to both humans and the environment. To address this, the principles of green chemistry can be applied to the design of new products and their manufacturing processes, to create green energetic materials that are virtually free of environmental hazards and toxicity issues during manufacturing, storage, use and disposal. Active research is underway to develop new ingredients and formulations, green synthetic methods and non-polluting manufacturing processes. Green Energetic Materials provides a detailed account of the most recent research and developments in the field, including green pyrotechnics, explosives and propellants. From theoretical modelling and design of new materials, to the development of sustainable manufacturing processes, this book addresses materials already on the production line, as well as considering future developments in this evolving field. Topics covered include: • Theoretical design of green energetic materials • Development of green pyrotechnics • Green primary and secondary explosives • Oxidisers and binder materials for green propellants • Environmentally sustainable manufacturing technologies for energetic materials • Electrochemical methods for synthesis of energetic materials and waste remediation Green Energetic Materials is a valuable resource for academic, industrial and governmental researchers working on the development of energetic materials, for both military and civilian applications.

  • 19.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Introduction to Green Energetic Materials2014In: Green Energetic Materials, Wiley-Blackwell, 2014, p. 1-14Chapter in book (Refereed)
    Abstract [en]

    This chapter begins with a short summary of the history of energetic materials. It is emphasized that developments generally have been driven by the objectives of improving performance and safety of handling. In addition to these objectives, new materials should also be green. This requirement is considered in relation to green chemistry and other tools for improving the sustainability of new products. A definition of a green energetic materials from the principles of green chemistry is presented. The chapter goes on to analyze past and present attempts to introduce green propulsion technologies to civil space travel. This analysis shows that the development of a green propellant system and its associated engine system is a lengthy and expensive process. The chances of succeeding seem to largely depend on the size of the engine system.

  • 20.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Preface2014In: Green Energetic Materials, Wiley-Blackwell, 2014, p. xi-xiiChapter in book (Refereed)
  • 21.
    Brinck, Tore
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Borrfors, Andre Nyberg
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    The Importance of Electrostatics and Polarization for Noncovalent Interactions: Ionic Hydrogen Bonds vs Ionic Halogen Bonds2022In: Journal of Molecular Modeling, ISSN 1610-2940, E-ISSN 0948-5023, Vol. 28, no 9, article id 275Article in journal (Refereed)
    Abstract [en]

    A series of 26 hydrogen-bonded complexes between Br- and halogen, oxygen and sulfur hydrogen-bond (HB) donors is investigated at the M06-2X/6-311 +G(2df,2p) level of theory. Analysis using a model in which Br- is replaced by a point charge shows that the interaction energy (Delta E-Int) of the complexes is accurately reproduced by the scaled interaction energy with the point charge (Delta E-Int(PC)). This is demonstrated by Delta E-Int = 0.86 Delta E-Int(PC) with a correlation coefficient, R-2=0.999. The only outlier is (Br-H-Br)(-), which generally is classified as a strong charge-transfer complex with covalent character rather than a HB complex. Delta E-Int(PC) can be divided rigorously into an electrostatic contribution (Delta E-ES(PC)) and a polarization contribution (Delta E-pol(PC)).Within the set of HB complexes investigated, the former varies between -7.2 and -32.7 kcal mol(-1), whereas the latter varies between -1.6 and -11.5 kcal mol(-1). Compared to our previous study of halogen-bonded (XB) complexes between Br and C-Br XB donors, the electrostatic contribution is generally stronger and the polarization contribution is generally weaker in the HB complexes. However, for both types of bonding, the variation in interaction strength can be reproduced accurately without invoking a charge-transfer term. For the Br-center dot center dot center dot HF complex, the importance of charge penetration on the variation of the interaction energy with intermolecular distance is investigated. It is shown that the repulsive character of Delta E-Int at short distances in this complex to a large extent can be attributed to charge penetration.

  • 22.
    Brinck, Tore
    et al.
    KTH, Superseded Departments (pre-2005), Chemistry.
    Carlqvist, P.
    Holm, A. H.
    Daasbjerg, K.
    Solvation of sulfur-centered cations and anions in acetonitrile2002In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 106, no 37, p. 8827-8833Article in journal (Refereed)
    Abstract [en]

    The solvation of substituted phenylsulfenium ions and thiophenoxides in acetonitrile has been analyzed on the basis of experimental and theoretical data. Experimental solvation energies are obtained from previously reported oxidation and reduction potentials of the corresponding arylthiyl radicals in combination with theoretically calculated ionization potentials and electron affinities at the B3LYP/6-31+G(d) level. These calculations provide a consistent set of values in contrast to the data sets obtained in our previous paper (Larsen et al., J. Am. Chem. Soc. 2001, 123, 1723). The extracted solvation data show the expected substituent dependency for both kinds of ions, i.e., the absolute value of the solvation energy decreases as the charge becomes more delocalized. For the thiophenoxides there is good agreement between the experimental solvation energies and solvation energies computed using the polarizable continuum model (PCM). The solvation of the arylsulfenium ions, is much stronger than predicted by the PCM method. This can be attributed to the formation of a strong covalent bond of the Ritter type between the arylsulfenium ion and one molecule of acetonitrile. When this interaction is included in the solvation energy calculations by means of a combined supermolecule and PCM approach the experimental data are reproduced within a few kcal mol(-1). While the energy difference of the singlet and triplet spin states of the arylsulfenium ions is almost negligible in gas phase, the singlet cation is undoubtedly the dominating species in solution, since the triplet cation lacks the ability to form a covalent bond with acetonitrile.

  • 23.
    Brinck, Tore
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Carlqvist, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Halldin Stenlid, Joakim
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Local Electron Attachment Energy and Its Use for Predicting Nucleophilic Reactions and Halogen Bonding2016In: JOURNAL OF PHYSICAL CHEMISTRY A, ISSN 1089-5639, Vol. 120, no 50, p. 10023-10032Article in journal (Refereed)
    Abstract [en]

    A new local property, the local electron attachment energy [E(r)], is introduced and is demonstrated to, be a useful guide to predict intermolecular interactions and chemical reactivity. The E(r) is analogous to the average local ionization energy but indicates susceptibility toward interactions with nucleophiles rather than electrophiles. The functional form E(r) is motivated based on Janak's theorem and the piecewise linear energy dependence of electron addition to atomic and molecular systems. Within the generalized Kohn-Sham method (GKS-DFT), only the virtual orbitals with negative eigenvalues contribute to E(r). In the, present study, E(r) has been computed from orbitals obtained from GKS-DFT computations with a hybrid exchange correlation functional. It is shown that E(r) computed on a molecular isodengty surface, E-S(r), reflects the regioselectivity and relative reactivity for nucleophilic aromatic substitution, nucleophilic addition to activated double bonds, and formation of halogen bonds. Good to excellent correlations between experimental or theoretical measures of interaction strengths and minima in E-S(r) (E-S,E-min) are demonstrated.

    Download full text (pdf)
    fulltext
  • 24.
    Brinck, Tore
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Haeberlein, Markus
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Nuclear Chemistry.
    A Computational Analysis of Substituent Effects on the O-H Bond Dissociation Energy in Phenols: Polar Versus Radical Effects1997In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 119, no 18, p. 4239-4244Article in journal (Refereed)
  • 25.
    Brinck, Tore
    et al.
    KTH, Superseded Departments (pre-2005), Chemistry.
    Jin, P.
    Ma, Y. G.
    Murray, J. S.
    Politzer, P.
    Segmental analysis of molecular surface electrostatic potentials: application to enzyme inhibition2003In: Journal of Molecular Modeling, ISSN 1610-2940, E-ISSN 0948-5023, Vol. 9, no 2, p. 77-83Article in journal (Refereed)
    Abstract [en]

    We have recently shown that the anti-HIV activities of reverse transcriptase inhibitors can be related quantitatively to properties of the electrostatic potentials on their molecular surfaces. We now introduce the technique of using only segments of the drug molecules in developing such expressions. If an improved correlation is obtained for a given family of compounds, it would suggest that the segment being used plays a key role in the interaction. We demonstrate the procedure for three groups of drugs, two acting on reverse transcriptase and one on HIV protease. Segmental analysis is found to be definitely beneficial in one case, less markedly so in another, and to have a negative effect in the third. The last result indicates that major portions of the molecular surfaces are involved in the interactions and that the entire molecules need to be considered, in contrast to the first two examples, in which certain segments appear to be of primary importance. This initial exploratory study shows that segmental analysis can provide insight into the nature of the process being investigated, as well as possibly enhancing the predictive capability.

  • 26.
    Brinck, Tore
    et al.
    KTH, Superseded Departments (pre-2005), Chemistry.
    Larsen, A. G.
    Madsen, K. M.
    Daasbjerg, K.
    Solvation of carbanions in organic solvents: A test of the polarizable continuum model2000In: Journal of Physical Chemistry B, ISSN 1089-5647, Vol. 104, no 42, p. 9887-9893Article in journal (Refereed)
    Abstract [en]

    The solvation of carbanions in the solvents N,N-dimethylformamide (DMF) and tetrahydrofuran (THF) has been analyzed on the basis of experimental and theoretical data. Experimental solvation energies are obtained from present and previously reported electrochemical measurements of reduction potentials of the corresponding radicals. Theoretical solvation energies are obtained from quantum chemical calculations using the polarizable continuum model (PCM). It is found that the solvation energy is relatively independent of molecular size and structure for the saturated carbanions. This indicates that the negative charge is strongly localized to the anionic carbon. The conjugated carbanions have considerably lower absolute solvation energies (\ DeltaG degrees (sol)\) than the saturated carbanions. This is a consequence of the strong delocalization of the negative charge in the former group. The propargyl anion is also found to have a surprisingly low absolute solvation energy. However, high-level quantum chemical calculations show that the electronic structure has large contributions from two different resonance structures, CH=CCH2- and -CH=C=CH2, which results in a significant charge delocalization. There is good agreement between calculated and experimental solvation energies for both the conjugated and nonconjugated primary anions. However, the PCM method consistently underestimates the absolute solvation energies of the secondary and tertiary carbanions. This is attributed to an insufficient treatment of first-layer solvation effects in the method. According to the experimental measurements, the absolute solvation energies are on average 2-3 kcal mol(-1) lower in THF than in DMF. The theoretical data indicate a considerably larger solvent effect, 7-10 kcal mol(-1). The discrepancy between theory and experiment may partly be attributed to the use of a supporting electrolyte in the measurements, but the main cause seems to be that the short-range interaction tendencies of the solvent cannot be Fully characterized by its dielectric constant.

  • 27.
    Brinck, Tore
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Lee, Hau-Nan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Nuclear Chemistry.
    Quantum Chemical Studies on the Thermochemistry of Alkyl and Peroxyl Radicals.1999In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 103, p. 7094-7104-Article in journal (Refereed)
  • 28.
    Brinck, Tore
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Liljenberg, Magnus
    KTH.
    The use of quantum chemistry for mechanistic analyses of SeAR reactions2015In: Arene Chemistry: Reaction Mechanisms and Methods for Aromatic Compounds, wiley , 2015, p. 83-105Chapter in book (Other academic)
    Abstract [en]

    In this chapter, we review the current understanding of electrophilic aromatic substitution (SEAr) based on the latest experimental and quantum chemical studies. In addition, the most reliable and computationally effective methods for predicting regioselectivity and relative reactivity of SEAr are evaluated and described. The mechanism of nitration is analyzed in detail based on recent quantum chemical studies. In the gas phase, the reaction often has a contribution from a single-electron transfer (SET), and this contribution increases with the activation tendency of the aromatic substrate. The solution reaction lacks a driving force for SET, and the reaction has an early transition state that resembles an O-C coordinated π-complex in structure. In contrast, halogenation with molecular chlorine as the electrophile proceeds via a much later transition state that is more similar to the α-complex. Among the different reactivity descriptors that have been used to analyze regioselectivity and relative reactivity of SEAr, the average local ionization energy seems to have the best predictive power. As is generally the case for descriptor-based approaches, it is best suited for analyzing SEAr with early transition states. The α-complex approach has emerged as an alternative to reactivity descriptors for predicting regioselectivity. It is based on the assumption that the relative α-complex energies are similar to the corresponding transition state energies and thus reflect the positional selectivity for an aromatic substrate when reacting with a particular electrophile. The method provides quantitative predictions for halogenations but is not reliable for nitrations.

  • 29.
    Brinck, Tore
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry. University of New Orleans.
    Murray, JS
    Politzer, P
    Octanol Water Partition-Coefficients Expressed In Terms Of Solute Molecular-Surface Areas And Electrostatic Potentials1993In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 58, no 25, p. 7070-7073Article in journal (Refereed)
    Abstract [en]

    For 70 molecules of various types and sizes, it is shown that their experimental octanol/water partition coefficients can be represented quantitatively in terms of the solute's molecular surface area in conjunction with two statistically-based quantities calculated from its surface electrostatic potential; the latter are the average deviation of the potential and its total variance. An ab initio SCF approach was used to compute STO-3G*-optimized geometries and STO-5G* electrostatic potentials.

  • 30.
    Brinck, Tore
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Nyberg Borrfors, Andre
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry. KTH Royal Inst Technol, CBH, Dept Chem, Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Electrostatics and polarization determine the strength of the halogen bond: a red card for charge transfer2019In: Journal of Molecular Modeling, ISSN 1610-2940, E-ISSN 0948-5023, Vol. 25, no 5, article id 125Article in journal (Refereed)
    Abstract [en]

    A series of 20 halogen bonded complexes of the types R-Br center dot center dot center dot Br- (R is a substituted methyl group) and R '-CC-Br center dot center dot center dot Br- are investigated at the M06-2X/6-311+G(d,p) level of theory. Computations using a point-charge (PC) model, in which Br- is represented by a point charge in the electronic Hamiltonian, show that the halogen bond energy within this set of complexes is completely described by the interaction energy (E-PC) of the point charge. This is demonstrated by an excellent linear correlation between the quantum chemical interaction energy and E-PC with a slope of 0.88, a zero intercept, and a correlation coefficient of R-2=0.9995. Rigorous separation of E-PC into electrostatics and polarization shows the high importance of polarization for the strength of the halogen bond. Within the data set, the electrostatic interaction energy varies between 4 and-18kcal mol(-1), whereas the polarization energy varies between -4 and-10kcal mol(-1). The electrostatic interaction energy is correlated to the sum of the electron-withdrawing capacities of the substituents. The polarization energy generally decreases with increasing polarizability of the substituents, and polarization is mediated by the covalent bonds. The lower (more favorable) E-PC of CBr4---Br- compared to CF3Br center dot center dot center dot Br- is found to be determined by polarization as the electrostatic contribution is more favorable for CF3Br center dot center dot center dot Br-. The results of this study demonstrate that the halogen bond can be described accurately by electrostatics and polarization without any need to consider charge transfer.

  • 31.
    Brinck, Tore
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Rahm, M.
    Theoretical Design of Green Energetic Materials: Predicting Stability, Detection, Synthesis and Performance2014In: Green Energetic Materials, Wiley-Blackwell, 2014, p. 15-44Chapter in book (Other academic)
    Abstract [en]

    The objective of this chapter is to illustrate the use of modern quantum chemical methods in the rational design of energetic materials with targeted properties. In the first part we discuss the methods that are used for prediction of thermochemical data, and for analysis of decomposition pathways and kinetic stabilities of new compounds. We also describe how quantum chemical methods can be used for predicting spectroscopic data, synthesis pathways, and performance characteristics of energetic materials. In the remaining part of the chapter we provide examples of the theoretical characterization of a number of compounds with promising properties for use in green propellants. Two of these, 1-nitro-2-oxo-3-amino-triazene and tetraazatetrahedrane, combine high kinetic stabilities with excellent propulsion performance.

  • 32.
    Brinck, Tore
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Sahoo, Suman Kalyan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Anomalous π-backbonding in complexes between B(SiR3)3 and N2: catalytic activation and breaking of scaling relations2023In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 25, no 31, p. 21006-21019Article in journal (Refereed)
    Abstract [en]

    Chemical transformations of molecular nitrogen (N2), including the nitrogen reduction reaction (NRR), are difficult to catalyze because of the weak Lewis basicity of N2. In this study, it is shown that Lewis acids of the types B(SiR3)3 and B(GeR3)3 bind N2 and CO with anomalously short and strong B-N or B-C bonds. B(SiH3)3·N2 has a B-N bond length of 1.48 Å and a complexation enthalpy of −15.9 kcal mol−1 at the M06-2X/jun-cc-pVTZ level. The selective binding enhancement of N2 and CO is due to π-backbonding from Lewis acid to Lewis base, as demonstrated by orbital analysis and density difference plots. The π-backbonding is found to be a consequence of constructive orbital interactions between the diffuse and highly polarizable B-Si and B-Ge bond regions and the π and π* orbitals of N2. This interaction is strengthened by electron donating substituents on Si or Ge. The π-backbonding interaction is predicted to activate N2 for chemical transformation and reduction, as it decreases the electron density and increases the length of the N-N bond. The binding of N2 and CO by the B(SiR3)3 and B(GeR3)3 types of Lewis acids also has a strong σ-bonding contribution. The relatively high σ-bond strength is connected to the highly positive surface electrostatic potential [VS(r)] above the B atom in the tetragonal binding conformation, but the σ-bonding also has a significant coordinate covalent (dative) contribution. Electron withdrawing substituents increase the potential and the σ-bond strength, but favor the binding of regular Lewis acids, such as NH3 and F−, more strongly than binding of N2 and CO. Molecules of the types B(SiR3)3 and B(GeR3)3 are chemically labile and difficult to synthesize. Heterogenous catalysts with the wanted B(Si-)3 or B(Ge-)3 bonding motif may be prepared by boron doping of nanostructured silicon or germanium compounds. B-doped and hydrogenated silicene is found to have promising properties as catalyst for the electrochemical NRR.

  • 33.
    Brinck, Tore
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Stenlid, Joakim H.
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, SE-10691 Stockholm, Sweden..
    The Molecular Surface Property Approach: A Guide to Chemical Interactions in Chemistry, Medicine, and Material Science2019In: Advanced Theory and Simulations, E-ISSN 2513-0390, Vol. 2, no 1, article id 1800149Article in journal (Refereed)
    Abstract [en]

    The current status of the molecular surface property approach (MSPA) and its application for analysis and prediction of intermolecular interactions, including chemical reactivity, are reviewed. The MSPA allows for identification and characterization of all potential interaction sites of a molecule or nanoparticle by the computation of one or more molecular properties on an electronic isodensity surface. A wide range of interactions can be analyzed by three properties, which are well-defined within Kohn-Sham density functional theory. These are the electrostatic potential, the average local ionization energy, and the local electron attachment energy. The latter two do not only reflect the electrostatic contribution to a chemical interaction, but also the contributions from polarization and charge transfer. It is demonstrated that the MSPA has a high predictive capacity for non-covalent interactions, for example, hydrogen and halogen bonding, as well as organic substitution and addition reactions. The latter results open u p applications within drug design and medicinal chemistry. The application of MSPA has recently been extended to nanoparticles and extended surfaces of metals and metal oxides. In particular, nanostructural effects on the catalytic properties of noble metals are rationalized. The potential for using MSPA in rational design of heterogeneous catalysts is discussed.

    Download full text (pdf)
    fulltext
  • 34.
    Bui, Thi Diem Huong
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Brinck, Tore
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    p-block doped semi-metallic xenes as highly selective and efficient transition-metal free single atom catalysts for electrochemical CO reduction2023In: Journal of Materials Chemistry A, ISSN 2050-7488, E-ISSN 2050-7496, Vol. 12, no 4, p. 2110-2120Article in journal (Refereed)
    Abstract [en]

    The development of robust and inexpensive catalysts for the electrochemical CO reduction reaction (CORR) is key for sustainable production of valuable chemicals, yet it remains a long-standing challenge. Herein, we conduct a systematic theoretical investigation on p-block doping of semi-metallic xene monolayers to afford transition metal free catalysts for the CORR. Silicene (Si) and germanene (Ge) are suitable platforms for capturing the dopant (B/Al) to ensure high stability. Our single atom catalysts (SACs) are promising candidates for CORR due to their favorable initial CO adsorption and the selectivity of CO reduction over H2 evolution. B@Si, Al@Si, Al@Ge and B@Ge exhibit superior CORR catalytic activity with a limiting potential UL of 0.04, −0.39, −0.40, and −0.40 V, respectively. Notably, B@Si is identified as the best CORR electrocatalyst with an overpotential of less than 0.1 V. B@Si, Al@Si, Al@Ge exhibit high CORR selectivity towards CH3OH production, whereas B@Ge is predicted to form mainly CH4. The fundamental principles behind the outstanding CORR catalytic enhancement are disclosed by analyzing the structural and electronic configurations of two key intermediates, CO* and CHO*. CO* binds the dopant with moderate strength through a combination of σ-donation and π-backdonation unique for a transition metal free catalyst, whereas CHO* adsorbs strongly to the surface by the simultaneous binding to two neighboring atomic sites; consequently, the binding of the two intermediates breaks the scaling relation that limits the CORR activity of conventional catalysts. The optimal adsorption behaviors are attributed to the surface charge modulation induced by the substitutional doping. Hence, these findings may facilitate rational design of xene-based SACs for CORR and advance other catalytic applications.

  • 35. Bulat, Felipe A.
    et al.
    Toro-Labbé, Alejandro
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Murray, Jane S.
    Politzer, Peter
    Quantitative analysis of molecular surfaces: areas, volumes, electrostatic potentials and average local ionization energies2010In: Journal of Molecular Modeling, ISSN 1610-2940, E-ISSN 0948-5023, Vol. 16, no 11, p. 1679-1691Article in journal (Refereed)
    Abstract [en]

    We describe a procedure for performing quantitative analyses of fields f(r) on molecular surfaces, including statistical quantities and locating and evaluating their local extrema. Our approach avoids the need for explicit mathematical representation of the surface and can be implemented easily in existing graphical software, as it is based on the very popular representation of a surface as collection of polygons. We discuss applications involving the volumes, surface areas and molecular surface electrostatic potentials, and local ionization energies of a group of 11 molecules.

  • 36.
    Caraballo, Remi
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Rahm, Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Vongvilai, Pornrapee
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Phosphine-catalyzed disulfide metathesis2008In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, no 48, p. 6603-6605Article in journal (Refereed)
    Abstract [en]

    The reaction between disulfides and phosphines generates a reversible disulfide metathesis process.

  • 37.
    Caraballo, Rémi
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Deng, Lingquan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Amorim, Luis
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    pH-Dependent Mutarotation of 1-Thioaldoses in Water. Unexpected Behavior of (2S)-D-Aldopyranoses2010In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 75, no 18, p. 6115-6121Article in journal (Refereed)
    Abstract [en]

    The pH-dependent mutarotation of 1-thioaldopyranoses in aqueous media has been investigated. Anomerization readily occurred at lower and neutral pH for all aldopyranoses studied, whereas mainly for (2S)-D-aldopyranoses at higher pH. 1-Thio-D-mannopyranose and 1-thio-D-altropyranose showed very strong pH dependence where the anomeric equilibrium ratios changed dramatically from a preference for the beta-anomer at lower pH to the alpha-anomer at higher pH.

  • 38. Carlqvist, P.
    et al.
    Eklund, R.
    Brinck, Tore
    KTH, Superseded Departments (pre-2005), Chemistry.
    A theoretical study of the uncatalyzed and BF3-assisted Baeyer-Villiger reactions2001In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 66, no 4, p. 1193-1199Article in journal (Refereed)
    Abstract [en]

    The mechanisms for the uncatalyzed and boron trifluoride (BF3) assisted Baeyer-Villiger reactions between acetone and hydrogen peroxide have been investigated using high level ab initio [MP2 and CCSD(T)] and density functional theory (B3LYP) methods. Both steps in the uncatalyzed reaction are found to have very high transition state energies. It is clear that detectable amounts of the Crieege intermediate or the products cannot be formed without the aid of a catalyst. The main function of BF3 in both the addition step and the rearrangement (migration) step is to facilitate proton transfer. In the addition step the complexation of hydrogen peroxide with BF3 leads to an increased acidity of the attacking OH group, while in the rearrangement step BF3 takes active part in the proton-transfer process. This latter step is found to be rate determining with an activation free energy of 17.7 kcal/mol in organic solution. The products of the reaction are BF2OH, hydrogen fluoride, and methyl acetate. Thus, BF3 is not directly regenerated from the reaction.

  • 39. Carlqvist, P.
    et al.
    Eklund, R.
    Hult, Karl
    KTH, Superseded Departments (pre-2005), Biochemistry and Biotechnology.
    Brinck, Tore
    KTH, Superseded Departments (pre-2005), Chemistry.
    Rational design of a lipase to accommodate catalysis of Baeyer-Villiger oxidation with hydrogen peroxide2003In: Journal of Molecular Modeling, ISSN 1610-2940, E-ISSN 0948-5023, Vol. 9, no 3, p. 164-171Article in journal (Refereed)
    Abstract [en]

    The mechanism and potential energy surface for the Baeyer-Villiger oxidation of acetone with hydrogen peroxide catalyzed by a Ser105-Ala mutant of Candida antarctica Lipase B has been determined using ab initio and density functional theories. Initial substrate binding has been studied using an automated docking procedure and molecular dynamics simulations. Substrates were found to bind to the active site of the mutant. The activation energy for the first step of the reaction, the nucleophilic attack of hydrogen peroxide on the carbonyl carbon of hydrogen peroxide, was calculated to be 4.4 kcal mol(-1) at the B3LYP/6-31+G* level. The second step, involving the migration of the alkyl group, was found to be the rate-determining step with a computed activation energy of 19.9 kcal mol(-1) relative the reactant complex. Both steps were found to be lowered considerably in the reaction catalyzed by the mutated lipase, compared to the uncatalyzed reaction. The first step was lowered by 36.0 kcal mol(-1) and the second step by 19.5 kcal mol(-1). The second step of the reaction, the rearrangement step, has a high barrier of 27.7 kcal mol(-1) relative to the Criegee intermediate. This could lead to an accumulation of the intermediate. It is not clear whether this result is an artifact of the computational procedure, or an indication that further mutations of the active site are required.

  • 40.
    Carlqvist, Peter
    et al.
    KTH, Superseded Departments (pre-2005), Chemistry.
    Ostmark, H.
    Brinck, Tore
    KTH, Superseded Departments (pre-2005), Chemistry.
    Computational study of the amination of halobenzenes and phenylpentazole. A viable route to isolate the pentazolate anion?2004In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 69, no 9, p. 3222-3225Article in journal (Refereed)
    Abstract [en]

    Amination of halobenzenes, which proceeds via the benzyne intermediate (1), has been studied using quantum chemical methods. The computational data are in agreement with experimentally observed trends in reactivity and provide a qualitative explanation for the observed hydrogen isotope effects. To investigate if this is a viable way to isolate the pentazolate anion (2), the reactivities of the halobenzenes have been compared to phenylpentazole (3). The reaction energetics for phenylpentazole become favorable after complexation with Zn2+.

  • 41.
    Carlqvist, Peter
    et al.
    KTH, Superseded Departments (pre-2005), Chemistry.
    Ostmark, H.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    The stability of arylpentazoles2004In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 108, no 36, p. 7463-7467Article in journal (Refereed)
    Abstract [en]

    The stability of phenylpentazole along with para-substituted and ortho,para-substituted arylpentazoles have been studied using high-level density functional theory (DFT). The decomposition of arylpentazoles to N-2 and the corresponding azide is a first-order reaction, where the breaking of the N1-N2 bond is concomitant with cleavage of the N3-N4 bond. Calculations confirm that the stability of arylpentazoles increases with electron-donating groups and decreases with electron-withdrawing groups, in the para position, as found in experiments. The stabilizing effect of the electron-donating groups is shown to be due to a resonance interaction with the electron-withdrawing pentazole ring. Addition of solvation effects, using the polarizable continuum model to simulate the polar solvent methanol, increases the stability of arylpentazoles. This is due to a more polar ground state than transition state. The calculated free energies of activation for the arylpentazoles agree well with experimental results. From the calculations, the electron-withdrawing effect of the pentazole group is found to be similar to that of cyanide (-CN). Some new arylpentazoles with hydroxyl groups in the ortho position are proposed. These are predicted to be more stable than all previously synthesized neutral arylpentazoles.

  • 42.
    Carlqvist, Peter
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Svedendahl, Maria
    KTH, School of Biotechnology (BIO), Biochemistry.
    Branneby, Cecilia
    KTH, School of Biotechnology (BIO), Biochemistry.
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    Exploring the Active-Site of a Rationally Redesigned Lipase for Catalysis of Michael-Type Additions2005In: ChemBioChem, ISSN 1439-4227, E-ISSN 1439-7633, Vol. 6, p. 331-336Article in journal (Refereed)
    Abstract [en]

    Michael-type additions of various thiols and alpha,beta-unsaturated carbonyl compounds were performed in organic solvent catalyzed by wild-type and a rationally redesigned mutant of Candida antarctica lipase B. The mutant locks the nucleophilic serine 105 in the active-site; this results in a changed catalytic mechanism of the enzyme. The possibility of utilizing this mutant for Michael-type additions was initially explored by quantum-chemical calculations on the reaction between acrolein and methanethiol in a model system. The model system was constructed on the basis of docking and molecular-dynamics simulations and was designed to simulate the catalytic properties of the active site. The catalytic system was explored experimentally with a range of different substrates. The k(cat) values were found to be in the range of 10(-3) to 4 min(-1), similar to the values obtained with aldolase antibodies. The enzyme proficiency was 10(7). Furthermore, the Michael-type reactions followed saturation kinetics and were confirmed to take place in the enzyme active site.

  • 43.
    Clark, Tim
    et al.
    Univ Erlangen Nurnberg, Comp Chem Ctr, Nagelsbachstr 25, D-91052 Erlangen, Germany..
    Brinck, Tore
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    The Conversation on Non-Covalent Interactions: an introduction2022In: Journal of Molecular Modeling, ISSN 1610-2940, E-ISSN 0948-5023, Vol. 28, no 9, article id 272Article in journal (Other academic)
  • 44.
    Dong, Hai
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Rahm, Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Supramolecular Control in Carbohydrate Epimerization: Discovery of a New Anion Host−Guest System2008In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 130, p. 15270-15271Article in journal (Refereed)
    Abstract [en]

    A new anion-carbohydrate recognition system is described. Pyranosides with axial protons in 1-, 3-, and 5-position proved efficient, forming relatively strong complexes between the anion and the B-face of the carbohydrate. This system could furthermore be used in supramolecular control in Lattrell-Dax epimerization reactions, leading to either activation or deactivation effects.

  • 45.
    Dong, Hai
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Rahm, Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Thota, Niranjan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Deng, Lingquan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Control of the ambident reactivity of the nitrite ion2013In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 11, no 4, p. 648-653Article in journal (Refereed)
    Abstract [en]

    In previous studies, it was reported that a neighbouring equatorial ester group is essential for a good yield of nitrite-mediated triflate inversion, whereas with neighbouring benzyl ether groups or axial ester groups, mixtures are generally produced. In the present study, the origin of this difference was addressed. The ambident reactivity of the nitrite ion has been found to be the cause of the complex product formation observed, which can be controlled by a neighbouring equatorial ester group. Both N-attack and O-attack occur in the absence of the ester group, whereas O-attack is favoured in its presence. A neighbouring group assistance mechanism is proposed, in addition to steric effects, based on secondary interactions between the neighbouring ester group and the incoming nucleophile. High-level quantum mechanical calculations were carried out in order to delineate this effect. The theoretical results are in excellent agreement with experiments, and suggest a catalytic role for the neighbouring equatorial ester group.

  • 46.
    Fidalgo, Alexandre Barreiro
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Dahlgren, Björn
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Surface Reactions of H2O2, H-2, and O-2 in Aqueous Systems Containing ZrO22016In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, no 3, p. 1609-1614Article in journal (Refereed)
    Abstract [en]

    In radiolysis of water, three molecular products are formed (H2O2, O-2, and H-2). It has previously been shown that aqueous hydrogen peroxide is catalytically decomposed on many oxide surfaces and that the decomposition proceeds via the formation of surface-bound hydroxyl radicals. In this work, we have investigated the behavior of aqueous H-2 and O-2 in contact with ZrO2. Experiments were carried out in an autoclave with high H2 pressure and low O-2 pressure (40 and 0.2 bar, respectively). In the experiments the concentration of H-abstracting radicals was monitored as a function of time using tris(hydroxymethyl)aminomethane (Tris) as scavenger and the subsequent formation of formaldehyde to probe radical formation. The plausible formation of H2O2 was also monitored in the experiments. In addition, density functional theory (employing the hybrid PBE0 functional) was used to search for reaction pathways. The results from the,experiments show that hydrogen-abstracting radicals: are formed in the aqueous H2O2-system in contact with solid ZrO2. Formation of H2O2 is also detected, and the time dependent production of hydrogen-abstracting radicals follows the time-dependent H2O2 concentration, strongly:indicating that the radicals are produced upon catalytic decomposition of H2O2. The DFT study implies that H2O2 formation proceeds via a pathway where HO2 is a key intermediate. It is interesting to note that all the stable molecular products from aqueous radiolysis are precursors of quite intriguing radical reactions at water/oxide interfaces.

  • 47.
    Gracin, Sandra
    et al.
    KTH, Superseded Departments (pre-2005), Chemical Engineering and Technology.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Rasmuson, Åke C.
    KTH, Superseded Departments (pre-2005), Chemical Engineering and Technology.
    Prediction of Solubility of Solid Organic Compounds in Solvents by UNIFAC2002In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 41, no 20, p. 5114-5124Article in journal (Refereed)
    Abstract [en]

    Predictions of solubility of nine different solid organic fine chemical compounds in water and organic solvents of relevance to industrial processing are examined. UNIFAC interaction parameters are taken from standard reference literature, extracted from liquid-vapor equilibria. For most systems, predicted solubilities deviate more than 15% from experimental values. Deviations are due to uncertainties in the estimation of the activity of the pure solid as well as to deficiencies in the estimation of activity coefficients in the solution. By comparison with results from ab initio quantum chemical calculations of the elecrostatic potential on the molecular surface of the solutes, it can be shown that a key assumption of the UNIFAC approach is not necessarily fulfilled. The properties of a functional group may depend significantly on the properties of the rest of the molecule.

  • 48.
    Gustafsson, Camilla
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Vassiliev, Serguei
    Department of Biological Sciences, Brock University, Ontario, Canada.
    Kürten, Charlotte
    KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Syrén, Per-Olof
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Brinck, Tore
    MD Simulations Reveal Complex Water Paths in Squalene–Hopene Cyclase: Tunnel-Obstructing Mutations Increase the Flow of Water in the Active Site2017In: ACS Omega, E-ISSN 2470-1343, Vol. 2, no 11, p. 8495-8506Article in journal (Refereed)
    Abstract [en]

    Squalene–hopene cyclase catalyzes the cyclization of squalene to hopanoids. A previous study has identified a network of tunnels in the protein, where water molecules have been indicated to move. Blocking these tunnels by site-directed mutagenesis was found to change the activation entropy of the catalytic reaction from positive to negative with a concomitant lowering of the activation enthalpy. As a consequence, some variants are faster and others are slower than the wild type (wt) in vitro under optimal reaction conditions for the wt. In this study, molecular dynamics (MD) simulations have been performed for the wt and the variants to investigate how the mutations affect the protein structure and the water flow in the enzyme, hypothetically influencing the activation parameters. Interestingly, the tunnel-obstructing variants are associated with an increased flow of water in the active site, particularly close to the catalytic residue Asp376. MD simulations with the substrate present in the active site indicate that the distance for the rate-determining proton transfer between Asp376 and the substrate is longer in the tunnel-obstructing protein variants than in the wt. On the basis of the previous experimental results and the current MD results, we propose that the tunnel-obstructing variants, at least partly, could operate by a different catalytic mechanism, where the proton transfer may have contributions from a Grotthuss-like mechanism.

    Download full text (pdf)
    MD Simulations Reveal Complex Water Paths in Squalene–Hopene Cyclase: Tunnel-Obstructing Mutations Increase the Flow of Water in the Active Site
  • 49. Haeffner, F.
    et al.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    How does methyllithium invert? A density functional study2001In: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 20, no 24, p. 5134-5138Article in journal (Refereed)
    Abstract [en]

    Quantum chemical studies (B3LYP) of the inversion of methyllithium in both tetrameric and dimeric aggregates have been carried out. Results show that inversion occurs either via dissociation of the tetramer into the dimers, passage of a four-membered-ring transition state, and association of the dimers to form the inverted tetramer, or via a nonconcerted route involving an eight-membered-ring transition state. The activation energies of these two mechanisms are similar. However, the dissociative mechanism is ruled out by NMR experiments.

  • 50.
    Haeffner, Fredrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Barnham, Kevin J.
    Bush, Ashley I.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Generation of soluble oligomeric beta-amyloid species via copper catalyzed oxidation with implications for Alzheimer's disease: A DFT study2010In: Journal of Molecular Modeling, ISSN 1610-2940, E-ISSN 0948-5023, Vol. 16, no 6, p. 1103-1108Article in journal (Refereed)
    Abstract [en]

    A mechanism for the oxidation of a dimeric beta-amyloid copper ion complex is proposed based on DFT calculations. It involves the Met35 residue, which is believed to be important in the neurotoxicity causing Alzheimer's disease. Oxidation of Met35 is found to proceed readily with dioxygen when two Met35 residues are close to each other and the copper ion. This indicates that oxidants, such as hydrogen peroxide, are not necessary for oxidation of beta-amyloid copper ion complexes. Understanding these processes could be pivotal in gaining more knowledge of this complex disease and for the development of therapeutic treatments.

123 1 - 50 of 148
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf