Ändra sökning
Avgränsa sökresultatet
12 51 - 83 av 83
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • 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.
  • 51.
    Sakulsombat, Morakot
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Zhang, Yan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Dynamic Asymmetric Hemithioacetal Transformation by Lipase-Catalyzed gamma-Lactonization: In Situ Tandem Formation of 1,3-Oxathiolan-5-one Derivatives2012Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, nr 20, s. 6129-6132Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dynamic hemithioacetal systems were efficiently generated in organic solvents and subsequently allowed to react with a range of lipases. This resulted in direct, dynamic asymmetric transformation of the systems, leading to optically active 1,3-oxathiolan-5-one products. The tandem process identified lipase-catalyzed lactonization as a useful method for the resolution of optimal constituents with high chemo- and stereoselectivities.

  • 52. Salyi, S.
    et al.
    Kritikos, M.
    Akermark, B.
    Sun, Licheng C.
    Synthesis of an amino-functionalized model of the Fe-only hydrogenase active site2003Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 9, nr 2, s. 557-560Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A dinuclear 2Fe2S mimic 6 of the active site of the Fe-only hydrogenases has been synthesized. Complex 6 contains a free amino group which enables linkage to a protein backbone or to a redox active species for the study of electron transfer processes in proteins or in supramolecular systems. The structures of the complex 6 and its Boc-protected precursor 5 could be verified by X-ray crystallography.

  • 53.
    Sanchez-de-Armas, Rocio
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Xue, Liqin
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Ahlquist, Mårten S. G.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    One Site Is Enough: A Theoretical Investigation of Iron-Catalyzed Dehydrogenation of Formic Acid2013Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 19, nr 36, s. 11869-11873Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dehydrogenation of HCO2H: The reaction mechanism for the dehydrogenation of formic acid catalyzed by a highly active and selective iron complex (see figure) has been studied by DFT. The most favorable pathway shows the hydride in Fe-H complexes acting as a spectator ligand throughout the catalytic cycle. This result opens up the Fe complex for modification in order to achieve more efficient and selective catalysts.

  • 54.
    Schaufelberger, Fredrik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Hu, Lei
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Trans-Symmetric Dynamic Covalent Systems: Connected Transamination and Transimination Reactions2015Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, nr 27, s. 9776-9783Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The development of chemical transaminations as a new type of dynamic covalent reaction is described. The key 1,3-proton shift is under complete catalytic control and can be conducted orthogonally to, or simultaneous with, transimination in the presence of an amine to rapidly yield two-dimensional dynamic systems with a high degree of complexity evolution. The transamination-transimination systems are proven to be fully reversible, stable over several days, compatible with a range of functional groups, and highly tunable. Kinetic studies show transamination to be the rate-limiting reaction in the network. Furthermore, it was discovered that readily available quinuclidine is a highly potent catalyst for aldimine transaminations. This study demonstrates how connected dynamic reactions give rise to significantly larger systems than the unconnected counterparts, and shows how reversible isomerizations can be utilized as an effective diversity-generating element.

  • 55.
    Schaufelberger, Fredrik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Dynamic Covalent Organocatalysts Discovered from Catalytic Systems through Rapid Deconvolution Screening2015Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, nr 36, s. 12735-12740Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The first example of a bifunctional organocatalyst assembled through dynamic covalent chemistry (DCC) is described. The catalyst is based on reversible imine chemistry and can catalyze the Morita-Baylis-Hillman (MBH) reaction of enones with aldehydes or N-tosyl imines. Furthermore, these dynamic catalysts were shown to be optimizable through a systemic screening approach, in which large mixtures of catalyst structures were generated, and the optimal catalyst could be directly identified by using dynamic deconvolution. This strategy allowed one-pot synthesis and in situ evaluation of several potential catalysts without the need to separate, characterize, and purify each individual structure. The systems were furthermore shown to catalyze and re-equilibrate their own formation through a previously unknown thiourea-catalyzed transimination process.

  • 56.
    Schaufelberger, Fredrik
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Timmer, Brian J. J.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Ramström, Olof
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Resolving a Reactive Organometallic Intermediate from Dynamic Directing Group Systems by Selective C-H Activation2018Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 24, nr 1, s. 101-104Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Catalyst discovery from systems of potential precursors is a challenging endeavor. Herein, a new strategy applying dynamic chemistry to the identification of catalyst precursors from C-H activation of imines is proposed and evaluated. Using hydroacylation of imines as a model reaction, the selection of an organometallic reactive intermediate from a dynamic imine system, involving many potential directing group/metal entities, is demonstrated. The identity of the amplified reaction intermediate with the best directing group could be resolved in situ by ESI-MS, and coupling of the procedure to an iterative deconvolution protocol generated a system with high screening efficiency.

  • 57. Schmitt, H.
    et al.
    Lomoth, R.
    Magnuson, A.
    Park, J.
    Fryxelius, J.
    Kritikos, M.
    Martensson, J.
    Hammarstrom, L.
    Sun, Licheng C.
    Akermark, B.
    Synthesis, redox properties, and EPR spectroscopy of manganese(III) complexes of the ligand N,N-bis(2-hydroxybenzyl)-N '-2-hdroxybenzylidene-1,2-diaminoethane: Formation of mononuclear, dinuclear, and even higher nuclearity complexes2002Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 8, nr 16, s. 3757-3768Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The synthesis and characterization of the title trisphenolate ligand are described. From its reaction with manganese(iii) three complexes were isolated. The crystal structures revealed one pentacoordinate monomer and two similar dimers with different solvents of crystallization. In the dimers the metal ions are hexacoordinate and connected through bridging of two phenolates. A combination of electrochemistry and EPR spectroscopy showed that, in acetonitrile, the isolated batches were all identical and mainly monomeric, indicating that the mononuclear complex is in equilibrium with the dimer and perhaps also with complexes of higher nuclearity, as suggested by the detection of both the trimer and the tetramer by electrospray ionization mass spectrometry (ESI-MS). The successful use of the monomer batch as an epoxidation catalyst indicated that a high-valent manganese-oxo species can be formed, although it is probably short-lived. This is also suggested by EPR studies of the species formed by electrochemical oxidation of the complex. Upon one-electron oxidation, a manganese(iv) species was formed, which was at least partly converted to another species containing a phenoxy radical.

  • 58.
    Seashore-Ludlow, Brinton
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Villo, Piret
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Somfai, Peter
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Enantioselective Synthesis of anti-β-Hydroxy-α-Amido Esters by Asymmetric Transfer Hydrogenation in Emulsions2012Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, nr 23, s. 2719-2723Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Herein, we present two methods for an asymmetric transfer hydrogenation through the dynamic kinetic resolution of α-amido-β-ketoesters. These procedures yield the corresponding anti-β-hydroxy-α-amido esters in good yields and with good diastereo- and enantioselectivities. First, the scope of the reduction of α-amido-β-ketoesters by using triethylammonium formate azeotrope is examined. Then, an emulsion technology with sodium formate is explored, which allows for broader substrate scope, faster reaction times, and lower catalyst loading. Furthermore, these reactions are operationally simple and can be set up in air.

  • 59. Shirani, H.
    et al.
    Linares, M.
    Sigurdson, C. J.
    Lindgren, M.
    Norman, Patrick
    Linköping University, Sweden.
    Nilsson, K. P. R.
    A Palette of Fluorescent Thiophene-Based Ligands for the Identification of Protein Aggregates2015Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, nr 43, s. 15133-15137Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    By replacing the central thiophene unit of an anionic pentameric oligothiophene with other heterocyclic moities, a palette of pentameric thiophene-based ligands with distinct fluorescent properties were synthesized. All ligands displayed superior selectivity towards recombinant amyloid fibrils as well as disease-associated protein aggregates in tissue sections.

  • 60. Silipo, Alba
    et al.
    Larsbrink, Johan
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
    Marchetti, Roberta
    Lanzetta, Rosa
    Brumer, Harry
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
    Molinaro, Antonio
    NMR Spectroscopic Analysis Reveals Extensive Binding Interactions of Complex Xyloglucan Oligosaccharides with the Cellvibrio japonicus Glycoside Hydrolase Family 31 a-Xylosidase2012Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, nr 42, s. 13395-13404Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The study of the interaction of glycoside hydrolases with their substrates is fundamental to diverse applications in medicine, food and feed production, and biomass-resource utilization. Recent molecular modeling of the a-xylosidase CjXyl31A from the soil saprophyte Cellvibrio japonicus, together with protein crystallography and enzyme-kinetic analysis, has suggested that an appended PA14 protein domain, unique among glycoside hydrolase family 31 members, may confer specificity for large oligosaccharide fragments of the ubiquitous plant polysaccharide xyloglucan (J. Larsbrink, A. Izumi, F. M. Ibatullin, A. Nakhai, H. J. Gilbert, G. J. Davies, H. Brumer, Biochem. J. 2011, 436, 567580). In the present study, a combination of NMR spectroscopic techniques, including saturation transfer difference (STD) and transfer NOE (TR-NOE) spectroscopy, was used to reveal extensive interactions between CjXyl31A active-site variants and xyloglucan hexa- and heptasaccharides. The data specifically indicate that the enzyme recognizes the entire cello-tetraosyl backbone of the substrate and product in positive enzyme subsites and makes further significant interactions with internal pendant a-(1?6)-linked xylosyl units. As such, the present analysis provides an important rationalization of previous kinetic data on CjXyl31A and unique insight into the role of the PA14 domain, which was not otherwise obtainable by protein crystallography.

  • 61. Sohnel, T.
    et al.
    Brown, R.
    Kloo, Lars A.
    KTH, Tidigare Institutioner                               , Kemi.
    Schwerdtfeger, P.
    The stability of gold iodides in the gas phase and the solid state2001Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 7, nr 14, s. 3167-3173Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The stability of gold iodides in the oxidation state +I and +III is investigated at the ab initio and density functional level using relativistic and nonrelativistic energy-adjusted pseudopotentials for gold and iodine. The calculations reveal that relativistic effects stabilize the higher oxidation state of gold as expected, that is Au2I6 is thermodynamically stable at the relativistic level, whilst at the nonrelativistic level the complex of two iodine molecules weakly bound to both gold atoms in Au2I2 is energetically preferred. The rather low stability of AuI3 with respect to dissociation into AuI and I-2 Will make it difficult to isolate this species in the solid state as (possibly) Au2I6 or detect it by matrix-isolation techniques. The monomer Au-3, is Jahn-Teller distorted from the ideal trigonal planar (D-3h) form, but adopts a Y-shaped structure (in contrast to AuF3 and AuCl3), and in the nonrelativistic case can be described as I-2 weakly bound to AuI. Relativistic effects turn AuI3 from a static Jahn-Teller system to a dynamic one. For the yet undetected gas-phase species AuI accurate coupled-cluster calculations for the potential energy curve are used to predict vibrational-rotational constants. Solid-state density functional calculations are performed for AuI and Au2I6 in order to predict cohesive energies.

  • 62.
    Sun, Xianqiang
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Laroch, Genevieve
    Wang, Xu
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Bowman, Gregory R.
    Giguõre, Patrick M.
    Tu, Yaoquan
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Propagation of the Allosteric Modulation Induced by Sodium in the delta-Opioid Receptor2017Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 23, nr 19, s. 4615-4624Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Allosteric sodium in the helix bundle of a G protein-coupled receptor (GPCR) can modulate the receptor activation on the intracellular side. This phenomenon has confounded the GPCR community for decades. In this work, we present a theoretical model that reveals the mechanism of the allosteric modulation induced by sodium in the delta-opioid receptor. We found that the allosteric sodium ion exploits a distinct conformation of the key residue Trp2746.48 to propagate the modulation to helices 5 and 6, which further transmits along the helices and regulates their positions on the intracellular side. This mechanism is supported by subsequent functional assays. Remarkably, our results highlight the contrast between the allosteric effects towards two GPCR partners, the G protein and b-arrestin, as indicated by the fact that the allosteric modulation initiated by the sodium ion significantly affects the b-arrestin recruitment, while it alters the G protein signaling only moderately. We believe that the mechanism revealed in this work can be used to explain allosteric effects initiated by sodium in other GPCRs since the allosteric sodium is highly conserved across GPCRs. 

  • 63. Svensson, Per H.
    et al.
    Rosdahl, Jan
    Kloo, Lars
    Metal Iodides in Polyiodide Networks -The Structural Chemistry of Complex Gold Iodides with Excess of Iodine1999Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 5, nr 1, s. 305-311Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Theoretical calculations that compare the Ij ion and the [AuI4](-) ion show that they are closely related and have potential energy surface (PES) minima corresponding to an L-shaped structure. These calculations also indicate that the I-3(-) and [AuI2](-) ions should be exchangeable. These results were confirmed by the synthesis of the compounds (Et3S)[AuI4]. 2I(2) (1) and (Me3S)(2)[AuI4][I-3] (4), which have been characterised by X-ray diffraction, Raman and far-IR spectroscopy. The structure of 1 is made up of [AuI4](-) units coordinated by infinite zig-zag chains of I, molecules, and can be regarded as [AuI4](-) ions incorporated into a polyiodide network. The structure of 4 is closely related to those of the compounds of the M2Au2X6 family (M = Cs+, Rb+, NH4+, K+; X = Cl-, Br-, I-) which consist of square-planar [AuX4](-) and linear [AuX2](-) ions. However, in the structure of 4, the [AuX2](-) ions are replaced by IS ions.

  • 64. Teng, Chao
    et al.
    Yang, Xichuan
    Li, Shifeng
    Cheng, Ming
    Hagfeldt, Anders
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Wu, Li-Zhu
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Tuning the HOMO Energy Levels of Organic Dyes for Dye-Sensitized Solar Cells Based on Br(-)/Br(3)(-) Electrolytes2010Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 16, nr 44, s. 13127-13138Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A series of novel metal free organic dyes TC301-TC310 with relatively high HOMO levels were synthesized and applied in dye sensitized solar cells (DSCs) based on electrolytes that contain Br(-)/Br(3)- and I(-)/I(3)(-) The effects of additive Li(+) ions and the HOMO levels of the dyes have an important influence on properties of the dyes and performance of DSCs The addition of Li(+) ions in electrolytes can broaden the absorption spectra of the dyes on TiO(2) films and shift both the LUMO levels of the dyes and the conduction band of TiO(2) thus leading to the increase of J(sc) and the decrease of V(oc) Upon using Br(-)/Br(3)(-) instead of I(-)/I(3)(-), a large increase of V(oc) is attributed to the enlarged energy difference between the redox potentials of electrolyte and the Fermi level of TiO(2), as well as the suppressed electron recombination Incident photon to current efficiency (IPCE) action spectra, electrochemical impedance spectra, and nanosecond laser transient absorption reveal that both the electron collection yields and the dye regeneration yields ((sic)(r)) depend on the potential difference (the driving forces) between the oxidized dyes and the Br(-)/Br(3)(-) redox couple For the dyes for which the HOMO levels are more positive than the redox potential of Br(-)/Br(3)(-) sufficient driving forces lead to the longer effective electron diffusion lengths and almost the same efficient dye regenerations, whereas for the dyes for which the HOMO levels are similar to the redox potential of Br(-)/Br(3)(-), insufficient driving forces lead to shorter effective electron-diffusion lengths and inefficient dye regenerations

  • 65.
    Timmer, Brian
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi.
    Ramström, Olof
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi. Univ Massachusetts, Dept Chem, 1 Univ Ave, Lowell, MA 01854 USA;Linnaeus Univ, Dept Chem & Biomed Sci, S-39182 Kalmar, Sweden.
    Acid-Assisted Direct Olefin Metathesis of Unprotected Carbohydrates in Water2019Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 25, nr 63, s. 14408-14413Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The ability to use unprotected carbohydrates in olefin metathesis reactions in aqueous media is demonstrated. By using water-soluble, amine-functionalized Hoveyda-Grubbs catalysts under mildly acidic aqueous conditions, the self-metathesis of unprotected alkene-functionalized alpha-d-manno- and alpha-d-galactopyranosides could be achieved through minimization of nonproductive chelation and isomerization. Cross-metathesis with allyl alcohol could also be achieved with reasonable selectivity. The presence of small quantities (2.5 vol %) of acetic acid increased the formation of the self-metathesis product while significantly reducing the alkene isomerization process. The catalytic activity was furthermore retained in the presence of large amounts (0.01 mm) of protein, underlining the potential of this carbon-carbon bond-forming reaction under biological conditions. These results demonstrate the potential of directly using unprotected carbohydrate structures in olefin metathesis reactions under mild conditions compatible with biological systems, and thereby enabling their use in, for example, drug discovery and protein derivatization.

  • 66. Ullah, Farman
    et al.
    Zhao, Gui-Ling
    Deiana, Luca
    Zhu, Mingzhao
    Dziedzic, Pawel
    Ibrahem, Ismail
    Hammar, Peter
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Sun, Junliang
    Cordova, Armando
    Enantioselective Organocatalytic Conjugate Addition of Fluorocarbon Nucleophiles to alpha,beta-Unsaturated Aldehydes2009Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 15, nr 39, s. 10013-10017Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Highly chemo- and enantioselective organocatalytic conjugate additions of fluorocarbon nucleophiles to alpha,beta-unsaturated aldehydes and the construction of a quaternary carbon stereocenter bearing a fluorine atom with high enantioselectivity was reported. After extensive screening of catalysts and conditions, it was found that chiral amines 5-9 catalyzed the conjugate addition of FBSM 2a to enal 1a to form the corresponding bfluorobis(sulfonyl)methyl aldehyde 3a, which was reduced in situ to the alcohol derivative 4a, with enantiomeric excess (ee) values ranging from nearly racemic to 95%. Chiral protected diarylprolinols catalyzed the transformation with the highest stereoselectivity under reaction conditions and mediated the formation of 3a with high chemoselectivity. The highest enantioselectivity was achieved in toluene. The enantioselectivity was improved, possibly due to stabilization of the iminium intermediate, by the addition of an acid additive and performing the transformation in ethanol.

  • 67. Vallet, Valerie
    et al.
    Wahlgren, Ulf
    Grenthe, Ingmar
    KTH, Skolan för kemivetenskap (CHE), Kemi, Oorganisk kemi.
    Comment on "The water-exchange mechanism of the [UO2(OH2)(5)](2+) ion revisited: The importance of a proper treatment of electron correlation"2007Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 13, nr 36, s. 10294-10297Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 68. Vastila, P.
    et al.
    Zaitsev, A. B.
    Wettergren, J.
    Privalov, Timofei
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Adolfsson, H.
    The importance of alkali cations in the {RuCl2(p-cymene)}(2) -pseudodipeptide-catalyzed enantioselective transfer hydrogenation of ketones2006Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 12, nr 12, s. 3218-3225Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We studied the role of alkali cations in the [{RuCl2(p-cymene)}2]- pseudo-dipeptide-catalyzed enantioselective transfer hydrogenation of ketones with isopropanol. Lithium salts were shown to increase the enantioselectivity of the reaction when iPrONa or iPrOK was used as the base. Similar transfer-hydrogenation systems that employ chiral amino alcohol or monotosylated diamine ligands are not affected by the addition of lithium salts. These observations have led us to propose that an alternative reaction mechanism operates in pseudo-dipeptidebased systems, in which the alkali cation is an important player in the ligand-assisted hydrogen-transfer step. DFT calculations of the proposed transition-state (TS) models involving different cations (Li+, Na+, and K+) confirm a considerable loosening of the TS with larger cations. This loosening may be responsible for the fewer interactions between the substrate and the catalytic complex, leading to lower enantiodifferentiation. This mechanistic hypothesis has found additional experimental support; the low ee obtained with [BnNMe3]OH (a large cation) as base can be dramatically improved by introducing lithium cations into the system. Also, the complexation of Na+, K+, and Li+ cations by the addition of [15]crown-5 and [18]crown-6 ethers and cryptand 2.1.1 (which selectively bind to these cations and, thus, increase their bulkiness), respectively, to the reaction mixture led to a significant drop in the enantioselectivity of the reaction. The lithium effect has proved useful for enhancing the reduction of different aromatic and heteroaromatic ketones.

  • 69. Watson, M. A.
    et al.
    Salek, Pawel
    KTH, Tidigare Institutioner, Bioteknologi.
    Macak, P.
    Jaszunski, M.
    Helgaker, T.
    The calculation of indirect nuclear spin-spin coupling constants in large molecules2004Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 10, nr 18, s. 4627-4639Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present calculations of indirect nuclear spin-spin coupling constants in large molecular systems, performed using density functional theory. Such calculations, which have become possible because of the use of linear-scaling techniques in the evaluation of the Coulomb and exchange-correlation contributions to the electronic energy, allow us to study indirect spin-spin couplings in molecules of biological interest, without having to construct artificial model systems. In addition to presenting a statistical analysis of the large number of short-range coupling constants in large molecular systems, we analyse the asymptotic dependence of the indirect nuclear spin-spin coupling constants on the internuclear separation. In particular, we demonstrate that, in a sufficiently large one-electron basis set, the indirect spin-spin coupling constants become proportional to the inverse cube of the internuclear separation, even though the diamagnetic and paramagnetic spin-orbit contributions to the spin-spin coupling constants separately decay as the inverse square of this separation. By contrast, the triplet Fermi contact and spin-dipole contributions to the indirect spin-spin coupling constants decay exponentially and as the inverse cube of the internuclear separation, respectively. Thus, whereas short-range indirect spin-spin coupling constants are usually dominated by the Fermi contact contribution, long-range coupling constants are always dominated by the negative diamagnetic spin-orbit contribution and by the positive paramagnetic spin-orbit contribution, with small spin-dipole and negligible Fermi contact contributions.

  • 70.
    Wen, Ye-Qian
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Hertzberg, Robin
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Gonzalez, Inanllely
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Moberg, Christina
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Minor Enantiomer Recycling: Application to Enantioselective Syntheses of Beta Blockers2014Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, nr 13, s. 3806-3812Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Continuous recycling of the minor product enantiomer obtained from the acetylcyanation of prochiral aldehydes provided access to highly enantiomerically enriched products. Cyanohydrin derivatives, which under normal conditions are obtained with modest or poor enantiomeric ratios, were formed with high enantiomeric purity by using a reinforcing combination of a chiral Lewis acid catalyst and a biocatalyst. The primarily obtained products were transformed into -adrenergic antagonists (S)-propanolol, (R)-dichloroisoproterenol, and (R)-pronethalol by means of a two-step procedure.

  • 71.
    Wingstrand, Erica
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Fransson, Linda
    KTH, Skolan för bioteknologi (BIO).
    Laurell, Anna
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Hult, Karl
    KTH, Skolan för bioteknologi (BIO).
    Moberg, Christina
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Minor enantiomer recycling: Metal catalyst, organocatalyst and biocatalyst working in concert2009Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 15, nr 44, s. 12107-12113Artikel i tidskrift (Refereegranskat)
    Abstract [en]

     A minor enantiomer recycling one-pot procedure employing two reinforcing chiral catalysts has been developed. Continuous regeneration of the achiral starting material is effected via selective enzyme-catalyzed hydrolysis of the minor product enantiomer from Lewis acid-Lewis base catalyzed addition of acyl cyanides to prochiral aldehydes in a two-phase solvent system. The process provides O-acylated cyanohydrins in close to perfect enantioselectivities, higher than those obtained in the direct process, and in high yields. A combination of a (SS)salen Ti Lewis acid and Candida antarctica lipase B provides the products with R absolute configuration, whereas the opposite enantiomer is obtained from the (R,R)-salen Ti complex and Candida rugosa lipase.

  • 72. Xu, Y. H.
    et al.
    Eilers, G.
    Borgstrom, M.
    Pan, J. X.
    Abrahamsson, M.
    Magnuson, A.
    Lomoth, R.
    Bergquist, J.
    Polivka, T.
    Sun, Licheng C.
    Sundstrom, V.
    Styring, S.
    Hammarstrom, L.
    Akermark, B.
    Synthesis and characterization of dinuclear ruthenium complexes covalently linked to Ru-II tris-bipyridine: An approach to mimics of the donor side of photosystem II2005Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 11, nr 24, s. 7305-7314Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To mimic the electron-donor side of photosystem II (PSII), three trinuclear ruthenium complexes (2, 2a, 2b) were synthesized. In these compl plexes, a mixed-valent dinuclear Ru-2(II,III) moiety with one phenoxy and two acetato bridges is covalently linked to a Ru-II tris-bipyridine photosensitizer. The properties and photoinduced electron/energy transfer of these complexes were studied. The results show that the Ru-2(II,III) moieties in the complexes readily undergo reversible one-electron reduction and one-electron oxidation to give the Ru-2(II,II) and Ru-2(II,III) states, respectively. This could allow for photooxidation of the sensitizer part with an external acceptor and subsequent electron transfer from the dinuclear ruthenium moiety to regenerate the sensitizer. However, all trinuclear ruthenium complexes have a very short excited-state lifetime, in the range of a few nanoseconds to less than 100 ps. Studies by femtosecond time-resolved techniques suggest that a mixture of intramolecular energy and electron transfer between the dinuclear ruthenium moiety and the excited [Ru(bpy)(3)](2+) photosensitizer is responsible for the short lifetimes. This problem is overcome by anchoring the complexes with ester- or carboxyl-substituted bipyridine ligands (2a, 2b) to nanocrystalline TiO2, and the desired electron transfer from the excited state of the [Ru(bPY)(3)](2+) moiety to the conduction band of TiO2, followed by intramolecular electron transfer from the dinuclear Ru-2(II,III) moiety to photogenerated Ru-III was observed. The resulting long-lived Ru-2(III,III) state decays on the millisecond timescale.

  • 73.
    Xu, Yunhua
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Duan, Lele
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Akermark, Torbjorn
    Tong, Lianpeng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Lee, Bao-Lin
    Zhang, Rong
    Akermark, Bjorn
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Synthesis and Catalytic Water Oxidation Activities of Ruthenium Complexes Containing Neutral Ligands2011Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 17, nr 34, s. 9520-9528Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two dinuclear and one mononuclear ruthenium complexes containing neutral polypyridyl ligands have been synthesised as pre-water oxidation catalysts and characterised by (1)H and (13)C NMR spectroscopy and ESI-MS. Their catalytic water oxidation properties in the presence of [Ce(NH(4))(2)(NO(3))(6)] (Ce(IV)) as oxidant at pH 1.0 have been investigated. At low concentrations of Ce(IV) (5 mm), high turnover numbers of up to 4500 have been achieved. An (18)O-labelling experiment established that both O atoms in the evolved O(2) originate from water. Combined electrochemical study and electrospray ionisation mass spectrometric analysis suggest that ligand exchange between coordinated 4-picoline and free water produces Ru aquo species as the real water oxidation catalysts.

  • 74.
    Yan, Mingdi
    Department of Chemistry, Portland State University.
    Photochemically initiated single polymer immobilization2007Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 13, nr 15, s. 4138-4144Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This Concept article surveys methods for attaching single polymer molecules on solid substrates. A general approach to single polymer immobilization based on the photochemistry of perfluorophenylazides is elaborated.

  • 75.
    Zeglinski, Jacek
    et al.
    Univ Limerick, Mat & Surface Sci Inst, Chem & Environm Sci, Limerick, Ireland..
    Kuhs, Manuel
    Univ Limerick, Mat & Surface Sci Inst, Chem & Environm Sci, Limerick, Ireland..
    Khamar, Dikshitkumar
    Univ Limerick, Mat & Surface Sci Inst, Chem & Environm Sci, Limerick, Ireland..
    Hegarty, Avril C.
    Univ Limerick, MACSI, Dept Math & Stat, Limerick, Ireland..
    Devi, Renuka K.
    Univ Limerick, Mat & Surface Sci Inst, Chem & Environm Sci, Limerick, Ireland..
    Rasmuson, Åke C.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik. Univ Limerick, Mat & Surface Sci Inst, Chem & Environm Sci, Limerick, Ireland.
    Crystal Nucleation of Tolbutamide in Solution: Relationship to Solvent, Solute Conformation, and Solution Structure2018Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 24, nr 19, s. 4916-4926Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of the solvent in nucleation of tolbutamide, a medium-sized, flexible and polymorphic organic molecule, has been explored by measuring nucleation induction times, estimating solvent-solute interaction enthalpies using molecular modelling and calorimetric data, probing interactions and clustering with spectroscopy, and modelling solvent-dependence of molecular conformation in solution. The nucleation driving force required to reach the same induction time is strongly solvent-dependent, increasing in the order: acetonitrile < ethyl acetate < n-propanol < toluene. The combined DFT and MD modelling results show that in acetonitrile, ethyl acetate and n-propanol the nucleation difficulty is a function of the strength of solvent-solute interaction, with emphasis on the interaction with specific H-bonding polar sites of importance in the crystal structure. A clear exception from this rule is the most difficult nucleation in toluene despite the weakest solvent-solute interactions. However molecular dynamics modelling predicts that tolbutamide assumes an intramolecularly H-bonded conformation in toluene, substantially different from and more stable than the conformation in the crystal structure, and thus presenting an additional barrier to nucleation. This explains why nucleation in toluene is the most difficult and why the relatively higher propensity for aggregation of tolbutamide molecules in toluene solution, as observed with FTIR spectroscopy, does not translate into easier nucleation. Thus, our combined experimental and molecular modelling study suggests that the solvent can influence on the nucleation not only via differences in the desolvation but also through the influence on molecular conformation.

  • 76.
    Zhang, Wei
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Bah, Juho
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Wohlfarth, Andreas
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Franzen, Johan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    A Stereodivergent Strategy for the Preparation of Corynantheine and Ipecac Alkaloids, Their Epimers, and Analogues: Efficient Total Synthesis of ()- Dihydrocorynantheol, ()-Corynantheol, ()-Protoemetinol, ()- Corynantheal, ()-Protoemetine, and Related Natural and Nonnatural Compound2011Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 17, nr 49, s. 13814-13824Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Abstract: Here we present a general and common catalytic asymmetric strategy for the total and formal synthesis of a broad number of optically active natural products from the corynantheine and ipecac alkaloid families, for example, indoloACHTUNGTRENUNG[2,3-a]- and benzo[a]quinolizidines. Construction of the core alkaloid skeletons with the correct absolute and relative stereochemistry relies on an enantioselective and diastereodivergent one-pot cascade sequence followed by an additional diastereodivergent reaction step. This allows for enantio- and diastereoselective synthesis of three out of four possible epimers of the quinolizidine alkaloids that begin from common and easily accessible starting materials by using a common synthetic route. Focus has been made on excluding protecting groups and limiting isolation and purification of synthetic intermediates. This methodology is applied in the total synthesis of the natural products ()-dihydrocorynantheol, ()-hirsutinol, ()-corynantheol, ()-protometinol, ()-dihydrocorynantheal, ()-corynantheal, ()-protoemetine, ()-(15S)-hydroxydihydrocorynantheol, and an array of their nonnatural epimers. The potential of this strategy is also demonstrated in the synthesis of biologically interesting natural product analogues not accessible through synthetic elaboration of alkaloid precursors available from nature, for example, thieno[3,2-a]quinolizidine derivatives. We also report the formal synthesis of (+)-dihydrocorynantheine, ()-emetine, ()-cephaeline, ()-tubulosine, and ()-deoxytubulosine.

  • 77.
    Zhang, Yan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Thiazolidinones Derived from Dynamic Systemic Resolution of Complex Reversible-Reaction Networks2014Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, nr 12, s. 3288-3291Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A complex dynamic system based on a network of multiple reversible reactions has been established. The network was applied to a dynamic systemic resolution protocol based on kinetically controlled lipase-catalyzed transformations. This resulted in the formation of cyclized products, where two thiazolidinone compounds were efficiently produced from a range of potential transformations.

  • 78.
    Zhang, Yang
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Xie, Sheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Yan, Mingdi
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Dynamic Covalent Chemistry of Aldehyde Enamines: Bi-III- and Sc-III-Catalysis of Amine-Enamine Exchange2017Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 23, nr 49, s. 11908-11912Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The dynamic exchange of enamines from secondary amines and enolizable aldehydes has been demonstrated in organic solvents. The enamine exchange with amines was efficiently catalyzed by Bi(OTf)(3) and Sc(OTf)(3) (2mol%) and the equilibria (60mm) could be attained within hours at room temperature. The formed dynamic covalent systems displayed high stabilities in basic environment with <2% by-product formation within one week after complete equilibration. This study expands the scope of dynamic C-N bonds from imine chemistry to enamines, enabling further dynamic methodologies in exploration of this important class of structures in systems chemistry.

  • 79. Zhao, Guang-Jiu
    et al.
    Chen, Rui-Kui
    Sun, Meng-Tao
    Liu, Jian-Yong
    Li, Guang-Yue
    Gao, Yun-Ling
    Han, Ke-Li
    Yang, Xi-Chuan
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Photoinduced intramolecular charge transfer and S-2 fluorescence in thiophene-pi-conjugated donor-acceptor systems: Experimental and TDDFT studies2008Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 14, nr 23, s. 6935-6947Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Experimental and theoretical methods were used to study newly synthesized thiophene-pi-cojugated donor-acceptor compounds, which were found to exhibit efficient intramolecular charge-transfer emission in polar solvents with relatively large Stokes shifts and strong solvatochromism. To gain insight into the solvatochromic behavior of these compounds, the dependence of the spectra on solvent polarity was studied on the basis of Lippert-Mataga models. We found that intramolecular charge transfer in these donor-acceptor systems is significantly dependent on the electron-with-drawing substituents at the thienyl 2-position. The dependence of the absorption and emission spectra of these compounds in methanol on the concentration of trifluoroacetic acid was used to confirm intramolecular charge-tranfer emission. Moreover, the calculated absorption and emission energies, which are in accordance with the experimental values, suggested that fluorescence can be emitted from different geometric confirmations. In addition, a novel S-2 fluorescence phenomenon for some of these compounds was also be observed. The fluorescence excitation spectra were used to confirm the S-2 fluorescence. We demonstrate that S-2 fluorescence can be explained by the calculated energy gap between the S-2 and S-1 states of these molecules. Furthermore, nonlinear optical behavior of the thiophene-pi-conjugated compound with diethylcyanomethylphosphonate substituents was predicted in theory.

  • 80. Zhao, Gui-Ling
    et al.
    Ullah, Farman
    Deiana, Luca
    Lin, Shuangzheng
    Zhang, Qiong
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Sun, Junliang
    Ibrahem, Ismail
    Dziedzic, Pawel
    Córdova, Armando
    Dynamic Kinetic Asymmetric Transformation (DYKAT) by Combined Amine- and Transition-Metal-Catalyzed Enantioselective Cycloisomerization2010Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 16, nr 5, s. 1585-1591Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The first examples of one-pot highly chemo- and enantioselective dynamic kinetic asymmetric transformations (DYKATs) involving alpha,beta-unsaturated aldehydes and proparaylated carbon acids are presented. These DYKATs, which proceed by a combination of catalytic iminium activation, enamine activation, and Pd-0-catalyzed enyne cycloisomerization, give access to functionalized cyclopentenes wit. It up to. 99% ee and can be used for the generation of all-carbon quaternary stereocenters

  • 81. Zhao, L. Y.
    et al.
    Yang, W. S.
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Zhai, T. Y.
    Zhang, G. J.
    Yao, J. N.
    Nanotubes from isomeric dibenzoylmethane molecules2005Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 11, nr 12, s. 3773-3778Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Organic nanotubes of various diameters were fabricated from the isomeric molecule dibenzoylmethane (DBM) by using an immersing technique with ordered porous alumina membrane as the template. The ratio of the enol isomers of DBM increased as the diameters of the nanotubes decreased. In addition, although almost no fluorescence could be detected for the DBM monomer, a striking enhancement in the fluorescence emission intensity of the nanotubes was observed as the diameters decreased. This is due to the increased ratio of the enol isomers.

  • 82. Zhou, Chunfang
    et al.
    Afonso, Damien
    Valetti, Sabrina
    Feiler, Adam
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap. Nanologica AB, Sweden.
    Cardile, Venera
    Graziano, Adriana C. E.
    Conoci, Sabrina
    Sortino, Salvatore
    Targeted Photodynamic Therapy with a Folate/Sensitizer Assembly Produced from Mesoporous Silica2017Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 23, nr 32, s. 7672-7676Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A mesoporous silica material prepared by using folic acid (FA) as a template enables the effective encapsulation of meso-tetrakis(4-carboxyphenyl) porphyrin (TCPP) in its interior. Combination of steady-state and time-resolved absorption and emission spectroscopy demonstrate that FA and TCPP are released from the silica material to the aqueous phase in the form of a non-covalent assembly. This assembly does not form by simple mixing of the two components in the absence of silica, suggesting the key role of the material in the assembling process. The FA/TCPP assembly exhibits dual color fluorescence in the visible region, good photosensitization capability of singlet oxygen, and enhanced photo-induced mortality in KB cancer cells overexpressing folate receptor, if compared with the free components.

  • 83. Zhou, Yunyun
    et al.
    Zhuang, Yaping
    Li, Xin
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Yu, Lin
    Ding, Jiandong
    Zhu, Liangliang
    Selective Dual-Channel Imaging on Cyanostyryl-Modified Azulene Systems with Unimolecularly Tunable Visible-Near Infrared Luminescence2017Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 23, nr 32, s. 7642-7647Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Although organic light-emitting molecules have received a growing attention and applicability in modern bioimaging science, the design and control of complex photoluminescent properties in unimolecularly selective imaging remains a challenging topic. Considering that tunable multipathway imaging can be advantagedly connected with treatment processes in therapy, the integration of an azulene and a cyanostyryl moiety into one skeleton is carried out for the generation of in situ stimuli-responsive luminescent materials, with the aim to achieve tunable and effective emissions in distinct channels through smart molecular design on a single-molecular platform. This strategy takes advantage of 1) the Z/E isomerization of the cyanostyryl unit that can vary the push-pull effect of the substitution on azulene, accompanied by altering absorption and emission of individual excited states, and 2) an optimized excited-state regulation for opening a near infrared emissive channel and making up for a controllable dual-pathway luminescent system together with the utilization of visible emission. As exemplified by a demonstration of manipulating the luminescence at the cell level, the materials exhibit a superior application potential for unimolecularly selective imaging, labeling and probing events.

12 51 - 83 av 83
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • 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