| 1. |
- Axelsson, Anton, 1991, et al.
(författare)
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Asymmetric Synthesis of Dihydropyranones with Three Contiguous Stereocenters by an NHC-Catalyzed Kinetic Resolution
- 2021
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Ingår i: European Journal of Organic Chemistry. - : Wiley. - 1434-193X .- 1099-0690. ; 2021:25, s. 3657-3661
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Tidskriftsartikel (refereegranskat)abstract
- An oxidative NHC-catalyzed kinetic resolution (KR) of racemic mixtures is presented. The developed reaction furnishes tricyclic dihydropyranones with three contiguous stereocenters in excellent dia- and enantioselectivity, with good-to-moderate yields. Mechanistic studies indicate that the rate-determining step of the reaction is the formation of the Breslow intermediate, while the selectivity determining step occurs later in the mechanism. The presented methodology enables rapid synthesis of complex structures in a single step.
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| 2. |
- Runemark, August, 1993, et al.
(författare)
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Visible-Light-Driven Stereoselective Annulation of Alkyl Anilines and Dibenzoylethylenes via Electron Donor-Acceptor Complexes
- 2021
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 86:2, s. 1901-1910
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Tidskriftsartikel (refereegranskat)abstract
- A catalyst-free, stereoselective visible-light-driven annulation reaction between alkenes and N,N-substituted dialkyl anilines for the synthesis of substituted tetrahydroquinolines is presented. The reaction is driven by the photoexcitation of an electron donor-acceptor (EDA) complex, and the resulting products are obtained in good to high yields with complete diastereoselectivity. Mechanistic rationale and photochemical characterization of the EDA-complex are provided.
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| 3. |
- Saha, Ekata, 1992, et al.
(författare)
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Dual Role of Boronic Acid Modification in Enhancing Rheological and Photophysical Properties of Supramolecular Gels
- 2024
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Ingår i: Macromolecules. - 1520-5835 .- 0024-9297. ; 57:7, s. 3183-3189
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Tidskriftsartikel (refereegranskat)abstract
- Supramolecular gels derived from functionalized gelators offer diverse applications, and modifying the properties of existing organogels using guest molecules presents an attractive approach for designing functional gel materials with targeted properties. In this study, we investigated a method to enhance the mechanical and photophysical properties of readily prepared low molecular weight gels (LMWGs) through the incorporation of boronic acid derivatives. The leveraging of dynamic covalent bonding interactions between the hydroxyl groups of oxotriphenylhexanoates (OTHO) gelator and the boronic acid derivatives gave rise to a boronate adduct along with enhanced intermolecular aromatic stacking interactions between gelators and thereby reinforced the rheological and thermal stability of the doped OTHO gels. In an effort to probe the aforementioned aromatic interactions, we used a pyrene boronic acid dopant, which revealed that the spatial proximity between the aromatic groups of the boronic acid was close enough to display excimer formation. Our findings provide valuable insights into the regulation of mechanical strength, self-healing ability, and photophysical properties of supramolecular gels. Furthermore, this approach holds promise for broad applications in hydroxyl-containing LMWGs, enabling the development of functional gel materials with enhanced properties.
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| 4. |
- Thunberg, Johannes, 1982, et al.
(författare)
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Hybrid Metal-Organic Framework-Cellulose Materials Retaining High Porosity: ZIF-8@Cellulose Nanofibrils
- 2021
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Ingår i: Inorganics. - : MDPI AG. - 2304-6740. ; 9:11
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Tidskriftsartikel (refereegranskat)abstract
- Metal-organic frameworks have attracted a great deal of attention for future applications in numerous areas, including gas adsorption. However, in order for them to reach their full potential a substrate to provide an anchor may be needed. Ideally, this substrate should be environmentally friendly and renewable. Cellulose nanofibrils show potential in this area. Here we present a hybrid material created from the self-assembly of zeolitic imidazolate framework (ZIF-8) nanocrystals on cellulose nanofibrils (CNF) in aqueous medium. The CNF/ZIF-8 was freeze dried and formed free standing materials suitable for gas adsorption. A BET area of 1014 m(2) g(-1) was achieved for the CNF/ZIF-8 hybrid materials ZIF-8@cellulose which is comparable with reported values for free standing ZIF-8 materials, 1600 m(2) g(-1), considering the dilution with cellulose, and a considerable enhancement compared to CNF on its own, 32 m(2) g(-1).
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| 5. |
- Zacharias, Savannah C., et al.
(författare)
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Exploring Supramolecular Gels in Flow-Type Chemistry-Design and Preparation of Stationary Phases
- 2021
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 60:28, s. 10056-10063
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Tidskriftsartikel (refereegranskat)abstract
- Two major challenges facing chemical synthesis are product isolation and catalyst recovery. One method to overcome these challenges is to perform the synthesis in a flow system with a catalytic stationary phase. However, the polymeric catalytic materials used in flow systems are often laborious to produce. In this study, we investigate a novel supramolecular gel as a catalytic stationary phase material. The gel is based on a modular, easy to synthesize, oxotriphenylhexanoate (OTHO) gelator comprised of a catalytic unit designed to catalyze the Knoevenagel reaction. The catalytic organogel enhances the rate of product formation and can be reused five times. Use of the OTHO to construct catalytic gels is a flexible technique that can be utilized to improve product isolation and reduce wastage of the catalyst.
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| 6. |
- Zacharias, Savannah C., et al.
(författare)
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Solvatochromism and the effect of solvent on properties in a two-dimensional coordination polymer of cobalt-trimesate
- 2022
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Ingår i: CRYSTENGCOMM. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 24:13, s. 2393-2401
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Tidskriftsartikel (refereegranskat)abstract
- Stimuli responsive porous materials are being investigated for a plethora of potential applications. These materials have the ability to respond to their physical and chemical environment and thus provide an opportunity to study supramolecular type interactions. We present an investigation into the effects of guest inclusion on framework flexibility in a two-dimensional polymer network, {[Co(btc)(DMF)(2)]center dot xDMF}(n) (1) where btc is benzene-1,3,5-tricarboxylate (trimesate) and DMF N,N-dimethylformamide. Solvents for guest exchange were selected to explore different potential interactions, such as hydrogen bonding (water and alcohols) and it-stacking (benzonitrile) and to cover a wide range of polarities and molecular sizes. Results showed that all solvents used could be exchanged directly for the guest DMF with accompanying visible colour changes. The incorporation of the new guest solvent was confirmed by PXRD and thermal analysis. This process is reversible for most solvents. On removal of the guest DMF, the framework (1-f) is retained, but layers collapse to a less crystalline material. Only water and methanol are capable of penetrating the material to reconstitute the layers. The crystal structure of the guest-exchanged system with benzonitrile (2) showed that the coordination polymer framework is retained, albeit with a change in symmetry and interlayer spacing, making 1 an example of a 'breathing' coordination polymer. A survey of related structures in the CSD found that there are four common motifs, which cannot be predicted from either the composition or space group symmetry of the compound.
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