| 1. |
- Dunér, Gunnar, et al.
(författare)
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Surface-confined photopolymerization of pH-responsive acrylamide/acrylate brushes on polymer thin films
- 2008
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 24:14, s. 7559-7564
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Tidskriftsartikel (refereegranskat)abstract
- Dynamic acrylamide/acrylate polymeric brushes were synthesized at gold-plated quartz crystal surfaces. The crystals were initially coated with polystyrene-type thin films, derivatized with photolabile iniferter groups, and subsequently subjected to photoinitiated polymerization in acrylamide/acrylate monomer feeds. This surface-confined polymerization method enabled direct photocontrol over the polymerization, as followed by increased frequency responses of the crystal oscillations in a quartz crystal microbalance (QCM). The produced polymer layers were also found to be highly sensitive to external acid/base stimuli. Large oscillation frequency shifts were detected when the brushes were exposed to buffer solutions of different pH. The dynamic behavior of the resulting polymeric brushes was evaluated, and the extent of expansion and contraction of the films was monitored by the QCM setup in situ in real time. The resulting responses were rapid, and the effects were fully reversible. Low pH resulted in full contractions of the films, whereas higher pH yielded maximal expansion in order to minimize repulsion around the charged acrylate centers. The surfaces also proved to be very robust because the responsiveness was reproducible over many cycles of repeated expansion and contraction. Using ellipsometry, copolymer layers were estimated to be similar to 220 nm in a collapsed state and similar to 340 nm in the expanded state, effectively increasing the thickness of the film by 55%.
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| 2. |
- Zhou, Y., et al.
(författare)
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Organosilicon-mediated regioselective acetylation of carbohydrates
- 2012
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 48:43, s. 5370-5372
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Tidskriftsartikel (refereegranskat)abstract
- Organosilicon-mediated, regioselective acetylation of vicinal- and 1,3-diols is presented. Methyl trimethoxysilane or dimethyl dimethoxysilane was first used to form cyclic 1,3,2-dioxasilolane or 1,3,2-dioxasilinane intermediates, and subsequent acetate-catalyzed monoacylation was efficiently performed by addition of acetic anhydride or acetyl chloride under mild conditions. The reaction exhibited high regioselectivity, resulting in the same protection pattern as in organotin-mediated schemes.
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| 3. |
- Ren, Yansong, et al.
(författare)
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Multistimuli-Responsive Enaminitrile Molecular Switches Displaying H+-Induced Aggregate Emission, Metal Ion-Induced Turn-On Fluorescence, and Organogelation Properties
- 2018
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 140:42, s. 13640-13643
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Tidskriftsartikel (refereegranskat)abstract
- Multistimuli-responsive enaminitrile-based configurational switches displaying aggregation-induced emission (AIE), fluorescence turn-on effects, and super gelation 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 (Phi(F) up to 0.41) in the solid state. In response to Cu-II 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.
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| 4. |
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| 5. |
- Caraballo, Rémi, 1982-
(författare)
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Dynamic Sulfur Chemistry : Screening, Evaluation and Catalysis
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with the design, formation and evaluation of dynamic systems constructed by means of sulfur-containing reversible reactions, in organic and aqueous media and under mild conditions. In a first part, the synthesis of thioglycoside derivatives, constituting the biologically relevant starting components of the dynamic systems, is described. In addition, the pD-profile of the mutarotation process in aqueous media for a series of 1-thioaldoses is reported and revealed an astonishing beta-anomeric preference for all the carbohydrate analogs under acidic or neutral conditions. In a second part, the phosphine-catalyzed or -mediated disulfide metathesis for dynamic system generation in organic or aqueous media is presented, respectively. The direct in situ 1H STD-NMR resolution of a dynamic carbohydrate system in the presence of a target protein (Concanavalin A) proved the suitability and compatibility of such disulfide metathesis protocols for the discovery of biologically relevant ligands. In a third part, hemithioacetal formation is demonstrated as a new and efficient reversible reaction for the spontaneous generation of a dynamic system, despite a virtual character of the component associations in basic aqueous media. The direct in situ 1H STD-NMR identification of the best dynamic beta-galactosidase inhibitors from the dynamic HTA system was performed and the results were confirmed by inhibition studies. Thus, the HTA product formed from the reaction between 1-thiogalactopyranose and a pyridine carboxaldehyde derivative provided the best dynamic inhibitor. In a fourth and final part, a dynamic drug design strategy, where the best inhibitors from the aforementioned dynamic HTA system were used as model for the design of non-dynamic (or “static”) beta-galactosidase inhibitors, is depicted. Inhibition studies disclosed potent leads among the set of ligands.
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| 6. |
- Karalius, Antanas, et al.
(författare)
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Formation and Out-of-Equilibrium, High/Low State Switching of a Nitroaldol Dynamer in Neutral Aqueous Media
- 2020
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Ingår i: Angewandte Chemie International Edition. - : Wiley-VCH Verlag. - 1433-7851 .- 1521-3773. ; 59:9, s. 3434-3438
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Tidskriftsartikel (refereegranskat)abstract
- The nitroaldol reaction is demonstrated as an efficient dynamic covalent reaction in phosphate buffers at neutral pH. Rapid equilibration was recorded with pyridine-based aldehydes, and dynamic oligomerization could be achieved, leading to nitroaldol dynamers of up to 17 repeating units. The dynamers were applied in a coherent stimuli-responsive molecular system in which larger dynamers transiently existed out-of-equilibrium in a neutral aqueous system rich in formaldehyde, controlled by nitromethane.
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| 7. |
- Kong, Na, et al.
(författare)
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Carbohydrate conjugation through microwave-assisted functionalization of single-walled carbon nanotubes using perfluorophenyl azides
- 2015
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Ingår i: Carbohydrate Research. - : Elsevier BV. - 0008-6215 .- 1873-426X. ; 405, s. 33-38
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Tidskriftsartikel (refereegranskat)abstract
- Carbohydrate-functionalized single-walled carbon nanotubes (SWNTs) were synthesized using microwave-assisted reaction of perfluorophenyl azide with the nanotubes. The results showed that microwave radiation provides a rapid and effective means to covalently attach carbohydrates to SWNTs, producing carbohydrate-SWNT conjugates for biorecognition. The carbohydrate-functionalized SWNTs were furthermore shown to interact specifically with cognate carbohydrate-specific proteins (lectins), resulting in predicted recognition patterns. The carbohydrate-presenting SWNTs constitute a new platform for sensitive protein-or cell recognition, which pave the way for glycoconjugated carbon nanomaterials in biorecognition applications.
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| 8. |
- Kravchenko, Oleksandr, et al.
(författare)
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Stable CAAC-based Ruthenium Complexes for Dynamic Olefin Metathesis Under Mild Conditions
- 2021
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Ingår i: ChemCatChem. - : Wiley. - 1867-3880 .- 1867-3899. ; 13:22, s. 4841-4847
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Tidskriftsartikel (refereegranskat)abstract
- A series of olefin metathesis catalysts bearing cyclic (alkyl)(amino)carbene (CAAC) ligands of varying size and steric demand has been synthesized and evaluated in ring-closing-, self-, and cross-metathesis reactions at room temperature. The catalysts were also probed for potential applications in dynamic covalent chemistry. The majority of the catalysts showed high stability, and remained active in the reaction mixtures for several days, including in methanol-based solutions. Higher temperatures could be used to control the reactivity towards sterically challenging substrates, enabling formation of tetrasubstituted olefins. The CAAC complexes exhibited remarkable functional group tolerance towards heteroaromatic and nucleophilic additives, making them potentially useful in the screening of biologically active compounds.
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| 9. |
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| 10. |
- Neranon, Kitjanit, 1985-, et al.
(författare)
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Design, Synthesis and Self-Assembly of Functional Amphiphilic Metallodendrimers
- 2020
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Ingår i: ChemistryOpen. - : John Wiley & Sons. - 2191-1363. ; 9:1, s. 45-52
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Tidskriftsartikel (refereegranskat)abstract
- A new family of alkynylated, amphiphilic dendrimers consisting of amidoamine linkers connected to 5,5 '-functionalized 2,2 '-bipyridine cores has been developed and evaluated in the formation of metallodendrimers of different generations and in self-assembly protocols. A convergent synthetic strategy was applied to provide dumbbell-shaped amphiphilic dendrimers, where the 2,2 '-bipyridine cores could be coordinated to Fe-II centers to afford corresponding metallodendrimers. The ability of the metallic- and non-metallic dendritic structures to self-assemble into functional supramolecular aggregates were furthermore evaluated in aqueous solution. Spherical aggregates with sizes of a few hundred nanometers were generally produced, where controlled disassembly of the metallodendrimers through decomplexation could be achieved.
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