| 1. |
- Beeren, Sophie R., et al.
(författare)
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The mechanical bond in biological systems
- 2023
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Ingår i: Chem. - : Elsevier BV. - 2451-9308 .- 2451-9294. ; 9:6, s. 1378-1412
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Forskningsöversikt (refereegranskat)abstract
- The field of mechanically interlocked molecules (MIMs) has advanced rapidly in recent years, with much work focused on their use in materials, sensing, and catalysis. However, the use of MIMs in biology and biomedicine has been limited, despite the identifica-tion of naturally occurring MIMs in DNA and proteins and the poten-tial advantages of the mechanical bond in fields such as nanomedi-cine and tissue engineering. Difficulties in the synthesis of MIMs, along with their limited solubility and stability in biological media, have until recently impeded their wider application in biology. Contemporary advances have, however, enabled a broader integra-tion of the mechanical bond in biology; the mechanical interlocking endows these systems with unique functional advantages. Herein, we summarize recent advances in the application of small-molecule, biologically derived, and polymeric MIMs in biology, highlighting synergies ripe for future exploration.
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| 2. |
- Das, Satyajit, et al.
(författare)
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Interlocked structures on active duty
- 2023
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Ingår i: Nature Chemistry. - : Springer Nature. - 1755-4330 .- 1755-4349. ; 15:2, s. 160-162
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Tidskriftsartikel (refereegranskat)abstract
- Interlocking macrocyclic carbon nanomaterials is an exciting way to tune their molecular properties, but all-conjugated catenanes and rotaxanes are extremely challenging to make. Now, fully π-conjugated [2]- and [3]catenanes as well as a [3]rotaxane have been prepared through an ‘active metal template’ approach.
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| 3. |
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| 4. |
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| 5. |
- Hu, Lei, et al.
(författare)
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Efficient asymmetric synthesis of lamivudine via enzymatic dynamic kinetic resolution
- 2013
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 49:88, s. 10376-10378
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Tidskriftsartikel (refereegranskat)abstract
- The anti-HIV nucleoside lamivudine was asymmetrically synthesized in only three steps via a novel surfactant-treated subtilisin Carlsberg-catalyzed dynamic kinetic resolution protocol. The enantiomer of lamivudine could also be accessed using the same protocol catalyzed by Candida antarctica lipase B.
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| 6. |
- Leigh, David A., et al.
(författare)
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Tying different knots in a molecular strand
- 2020
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 584:7822, s. 562-568
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Tidskriftsartikel (refereegranskat)abstract
- The properties of knots are exploited in a range of applications, from shoelaces to the knots used for climbing, fishing and sailing1. Although knots are found in DNA and proteins2, and form randomly in other long polymer chains3,4, methods for tying5different sorts of knots in a synthetic nanoscale strand are lacking. Molecular knots of high symmetry have previously been synthesized by using non-covalent interactions to assemble and entangle molecular chains6–15, but in such instances the template and/or strand structure intrinsically determines topology, which means that only one type of knot is usually possible. Here we show that interspersing coordination sites for different metal ions within an artificial molecular strand enables it to be tied into multiple knots. Three topoisomers—an unknot (01) macrocycle, a trefoil (31) knot6–15, and a three-twist (52) knot—were each selectively prepared from the same molecular strand by using transition-metal and lanthanide ions to guide chain folding in a manner reminiscent of the action of protein chaperones16. We find that the metal-ion-induced folding can proceed with stereoinduction: in the case of one knot, a lanthanide(iii)-coordinated crossing pattern formed only with a copper(i)-coordinated crossing of particular handedness. In an unanticipated finding, metal-ion coordination was also found to translocate an entanglement from one region of a knotted molecular structure to another, resulting in an increase in writhe (topological strain) in the new knotted conformation. The knot topology affects the chemical properties of the strand: whereas the tighter 52knot can bind two different metal ions simultaneously, the looser 31 isomer can bind only either one copper(i) ion or one lutetium(iii) ion. The ability to tie nanoscale chains into different knots offers opportunities to explore the modification of the structure and properties of synthetic oligomers, polymers and supramolecules.
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| 7. |
- Schaufelberger, Fredrik, et al.
(författare)
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Activated Self-Resolution and Error-Correction in Catalytic Reaction Networks
- 2021
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Ingår i: Chemistry - A European Journal. - : John Wiley & Sons. - 0947-6539 .- 1521-3765. ; 27:40, s. 10335-10340
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the emergence of function in complex reaction networks is a primary goal of systems chemistry and origin-of-life studies. Especially challenging is to create systems that simultaneously exhibit several emergent functions that can be independently tuned. In this work, a multifunctional complex reaction network of nucleophilic small molecule catalysts for the Morita-Baylis-Hillman (MBH) reaction is demonstrated. The dynamic system exhibited triggered self-resolution, preferentially amplifying a specific catalyst/product set out of a many potential alternatives. By utilizing selective reversibility of the products of the reaction set, systemic thermodynamically driven error-correction could also be introduced. To achieve this, a dynamic covalent MBH reaction based on adducts with internal H-transfer capabilities was developed. By careful tuning of the substituents, rate accelerations of retro-MBH reactions of up to four orders of magnitude could be obtained. This study thus demonstrates how efficient self-sorting of catalytic systems can be achieved through an interplay of several complex emergent functionalities.
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| 8. |
- Schaufelberger, Fredrik, 1987-, et al.
(författare)
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Biomimetic Hydrogen Bonding Catalysis of Imine Exchange for Rapid Equilibration of Dynamic Systems
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The reversibility of imine bonds has been exploited to great effect in the field of dynamic covalent chemistry, for example in the preparation of dynamic systems for a wide variety of applications. However, acid catalysis is commonly needed for efficient equilibration of imine mixtures. Herein, it is demonstrated that hydrogen bond donors, such as thioureas and squaramides, can catalyze the equilibration of dynamic imine systems under unprecedentedly mild conditions. Catalysis occurs in a range of solvents and in the presence of many sensitive additives, showing moderate to good rate accelerations for both imine metathesis and transimination with amines, hydrazines and hydroxylamines. Furthermore, the catalyst proved simple to immobilize, introducing both reusability and extended control of the equilibration process.
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| 9. |
- Schaufelberger, Fredrik, 1987-
(författare)
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Catalysis in Dynamic Systems: Control within Molecular Reaction Networks
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Life as we know it is based on complex networks of biochemical reactions that constantly interact within large dynamic systems. The field of systems chemistry uses chemical models to study how reaction networks – and thereby life – function on a molecular level. This thesis focuses on different aspects of catalysis in dynamic systems of interconnected reversible reactions. Using the reversible imine bond as the primary tool, such dynamic systems have both been used for catalyst screening and to achieve emergent systemic behavior.First, constitutional dynamic chemistry was used to discover catalysts within large mixtures. A method based on dynamic deconvolution was used to identify a bifunctional organocatalyst for the Morita-Baylis-Hillman (MBH) reaction from a mixture of 16 candidates. A second method involved amplification of an organometallic intermediate from a dynamic system and was used to discover directing group/metal combinations for C-H functionalization of aldehydes.Subsequently, the consequences of integrating the catalyst itself into a dynamic system were investigated. Here, dynamic covalent catalysts formed reaction networks with programmable systemic properties. Using the MBH reaction and dynamic imine exchange, catalysts capable of self-resolution, feedback regulation and error-correction were constructed.Finally, selective catalyst systems for activation of new reversible covalent behavior for imines were developed. H-bond catalysis was used to facilitate imine exchange under mild conditions, and transamination was introduced as a dynamic covalent linkage that could change the directionality of the imine bond.The research in this thesis should both be applicable for catalyst discovery within synthetic organic chemistry, for understanding connectivity in chemical and biological systems as well as for studies of the origin of life on earth and the evolution of simple molecules into advanced systems with emergent functionality.
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