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  • 1.
    Hu, Lei
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ren, Yansong
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Chirality Control in Enzyme-Catalyzed Dynamic Kinetic Resolution of 1,3-Oxathiolanes2015In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 80, no 16, p. 8478-8481Article in journal (Refereed)
    Abstract [en]

    The origin of enantioenrichment in enzyme-catalyzed dynamic kinetic resolution of 1,3-oxathiolane derivatives, key intermediates for asymmetric lamivudine synthesis, was elucidated. The chirality control could be determined by chiral HPLC and NOE NMR spectroscopy using a modified 1,3-oxathiolane compound obtained through enzyme-catalyzed selective hydrolysis. Solvent-dependent stereoselectivity was observed under biphasic conditions using different organic solvents with phosphate buffer.

  • 2.
    REN, Yansong
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Dynamic Chemistry for Asymmetric Synthesis, Molecular Motion and Constitutional Exchange2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Living matter is built on complex dynamic systems consisting of numerus biotransformations. By exploiting the adaptive and evolutive behaviors ofmolecular matter, dynamic chemistry has developed as an important tool tounderstand the organization of nonliving matter into complex living systems.This thesis concerns three aspects of dynamic chemistry with a general focus onthe influence of different stimuli on the structures and functions of dynamicsystems.The first section focuses on dynamic kinetic resolution, where enzymes areutilized for asymmetric synthesis of an enantiopure (2R,5R)-1,3-oxathiolane. Byemploying surfactant-treated subtilisin Carlsberg and Candida antarcticalipase B, the absolute configuration of the resulting 1,3-oxathiolane ring couldbe efficiently controlled.The second section addresses the motional dynamics of configurational enamineswitch systems controlled by multiple stimuli. Complete forward and backwardrotation around the enamine C=C bond could be precisely regulated uponaddition of acid/base or metal ions. The enamine switches exhibited specificsensing ability for CuII ions in solution. Moreover, the enamines exhibitedswitchable aggregation-induced emission in the solid state, which could beapplied in the development of sensors as well as fluorescent organogel.Lastly, the enamine switches could readily undergo constitutional exchange withprimary amines under catalytic acidic conditions, resulting in dynamic enaminesystems. However, under basic conditions or in the presence of excessive acid,this process exhibited extremely slow kinetics, leading to an efficient regulationof the exchange process by controlling the switch status with regulation of pHin the system.

  • 3.
    REN, Yansong
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Hu, Lei
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Ramström, Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Multienzymatic Cascade Synthesis of an Enantiopure (2R,5R)-1,3-Oxathiolane Anti-HIV Agent PrecursorManuscript (preprint) (Other academic)
    Abstract [en]

    An enantiopure (2R,5R)-1,3-oxathiolane derivative was obtained using amultienzymatic cascade protocol. By employing a combination of surfactant-treatedsubtilisin Carlsberg and Candida antarctica lipase B, the absolute configuration of theresulting 1,3-oxathiolane ring was efficiently controlled, resulting in an excellentenantiomeric excess (> 99%). This enantiopure 1,3-oxathiolane derivative is a keyprecursor to anti-HIV agents, such as lamivudine, through subsequent N-glycosylation.

  • 4.
    REN, Yansong
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Kravchenko, Oleksandr
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Ramström, Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Configurational and Constitutional Dynamics in Enamine Molecular SwitchesManuscript (preprint) (Other academic)
    Abstract [en]

    Dual configurational and constitutional dynamics in systems based on enamine molecularswitches has been systematically studied. pH-responsive moieties, such as 2-pyridyl and 2-quinolinyl units, were required on the “stator” part, also providing enamine stability throughintramolecular hydrogen-bonding (IMHB) effects. Upon protonation or deprotonation, forward andbackward switching could be rapidly achieved. Extension of the stator π-system in the 2-quinolinylderivative provided a higher E-isomeric equilibrium ratio under neutral conditions, pointing to ameans to achieve quantitative forward/backward isomerization processes. The ‘rotor’ part of theenamine switches exhibited constitutional exchange ability with primary amines. Interestingly,considerably higher exchange rates were observed with amines containing ester groups, indicatingpotential stabilization of the transition state trough IMHB. Acids, particularly BiIII, were found toefficiently catalyze the constitutional dynamic processes. In contrast, the enamine and the formeddynamic enamine system showed excellent stability under basic conditions. This coupledconfigurational and constitutional dynamics expand the scope of dynamic C-C and C-N bonds, andpotentiates further studies and applications in the fields of molecular machinery and systemschemistry.

  • 5.
    REN, Yansong
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Kravchenko, Oleksandr
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Xie, Sheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Grape, Erik
    Inge, A. Ken
    Ramström, Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Stimuli-responsive Enaminitrile Molecular Switches as Tunable AIEgens Covering theChromaticity Space and Acting as Vapor SensorsManuscript (preprint) (Other academic)
    Abstract [en]

    A family of responsive enaminitrile molecular switches showing tunable turn-onfluorescence upon switching and aggregation is reported. Activated by addition of acid/base,isomerization around the C=C bond could be effectuated, resulting in complete, reversible switchingto the E- or Z-isomers. Typical aggregation-induced emission could be recorded for one specificstate of the different switches. By subtle tailoring of the parent structure, a series of compounds withemission covering almost the full visible color range were obtained. The switchable AIE features ofthe enaminitrile structures enabled their demonstration as solid state chemosensors to detect acidicand basic vapors, where the emission displayed an “off-on-off” effect. X-ray crystal analysis andDFT calculations suggested a restriction of intramolecular rotation mechanism, and anintramolecular charge transfer effect in the AIE luminogens.

  • 6.
    Ren, Yansong
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Svensson, Per H.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. RISE Biosci & Mat, Res Inst Sweden, Forskargatan 18, S-15136 Sodertalje, Sweden..
    Ramström, Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. Department of Chemistry, University of Massachusetts Lowell, 1 University Avenue, Lowell, MA, United States.
    A Multicontrolled Enamine Configurational Switch Undergoing Dynamic Constitutional Exchange2018In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 57, no 21, p. 6256-6260Article in journal (Refereed)
    Abstract [en]

    A multiresponsive enamine-based molecular switch is presented, in which forward/backward configurational rotation around the C=C bond could be precisely controlled by the addition of an acid/base or metal ions. Fluorescence turn-on/off effects and large Stokes shifts were observed while regulating the switching process with Cu-II. The enamine functionality furthermore enabled double dynamic regimes, in which configurational switching could operate in conjunction with constitutional enamine exchange of the rotor part. This behavior was used to construct a prototypical dynamic covalent switch system through enamine exchange with primary amines. The dynamic exchange process could be readily turned on/off by regulating the switch status with pH.

  • 7.
    REN, Yansong
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. KTH - Royal Institute of Technology.
    Xie, Sheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Grape, Erik
    Inge, A. Ken
    Ramström, Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Multistimuli-Responsive Enaminitrile Molecular Switches DisplayingH+‑Induced Aggregate Emission, Metal Ion-Induced Turn-OnFluorescence, and Organogelation Properties2018In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 140, no 42, p. 13640-13643Article in journal (Refereed)
    Abstract [en]

    Multistimuli-responsive enaminitrile-based configurational switches displaying aggregation-induced emission (AIE), fluorescence turn-on effects, and supergelation properties are presented. The E-isomers dominated (>97%) in neutral/basic solution, and the structures underwent precisely controlled switching around the enamine C═C bond upon addition of acid/base. Specific fluorescence output was observed in response to different external input in the solution and solid states. In response to H+, configurational switching resulted in complete formation of the nonemissive Z-H+-isomers in solution, however displaying deep-blue to blue fluorescence (ΦF up to 0.41) in the solid state. In response to CuII in the solution state, the E-isomers exhibited intense, turn-on, blue-green fluorescence, which could be turned off by addition of competitive coordination. The acid/base-activated switching, together with the induced AIE-effects, further enabled the accomplishment of a responsive superorganogelator. In nonpolar solvents, a blue-fluorescent supramolecular gel was formed upon addition of acid to the E-isomer suspension. The gelation could be reversed by addition of base, and the overall, reversible process could be repeated at least five cycles.

  • 8.
    Zhang, Yan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Zhang, Yang
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ren, Yansong
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Synthesis of chiral oxazolidinone derivatives through lipase-catalyzed kinetic resolution2015In: Journal of Molecular Catalysis B: Enzymatic, ISSN 1381-1177, E-ISSN 1873-3158, Vol. 122, p. 29-34Article in journal (Refereed)
    Abstract [en]

    The synthesis of enantioenriched oxazolidinone derivatives through lipase-catalyzed kinetic resolution is described. The synthesis comprised a two-step, cascade acylation in one pot, resulting in a range of oxazolidinone derivatives in good yields and excellent enantiopurities.

  • 9.
    Zhou, Juan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Jayawardana, Kalana
    University of Massachusetts, United States .
    Kong, Na
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ren, Yansong
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hao, Nanjing
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. University of Massachusetts, United States .
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Trehalose-Conjugated Mesoporous Silica Nanoparticles for Efficient Delivery of Isoniazid into MycobacteriaManuscript (preprint) (Other academic)
  • 10.
    Zhou, Juan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Jayawardana, Kalana W.
    Kong, Na
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ren, Yansong
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hao, Nanjing
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. University of Massachusetts, United States.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Trehalose-Conjugated, Photofunctionalized Mesoporous Silica Nanoparticles for Efficient Delivery of Isoniazid into Mycobacteria2015In: ACS BIOMATERIALS-SCIENCE & ENGINEERING, ISSN 2373-9878, Vol. 1, no 12, p. 1250-1255Article in journal (Refereed)
    Abstract [en]

    Glyconanoparticle carriers have been synthesized and efficiently delivered into mycobacteria. Mesoporous silica nanoparticles were functionalized with a,a-trehalose through azide-mediated surface photoligation, and loaded with the antitubercular drug isoniazid. The glyconanoparticles showed high isoniazid loading capacity and higher antimicrobial activity than the free drug.

1 - 10 of 10
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  • ieee
  • modern-language-association-8th-edition
  • vancouver
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  • en-US
  • fi-FI
  • nn-NO
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