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- Kuntze, Kim, et al.
(författare)
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A visible-light-driven molecular motor based on barbituric acid
- 2023
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Ingår i: Chemical Science. - : Royal Society of Chemistry. - 2041-6520 .- 2041-6539. ; 14:32, s. 8458-8465
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Tidskriftsartikel (refereegranskat)abstract
- We present a class of visible-light-driven molecular motors based on barbituric acid. Due to a serendipitous reactivity we observed during their synthesis, these motors possess a tertiary stereogenic centre on the upper half, characterised by a hydroxy group. Using a combination of femto- and nanosecond transient absorption spectroscopy, molecular dynamics simulations and low-temperature H-1 NMR experiments we found that these motors operate similarly to push-pull second-generation overcrowded alkene-based molecular motors. Interestingly, the hydroxy group at the stereocentre enables a hydrogen bond with the carbonyl groups of the barbituric acid lower half, which drives a sub-picosecond excited-state isomerisation, as observed spectroscopically. Computational simulations predict an excited state "lasso" mechanism where the intramolecular hydrogen bond pulls the molecule towards the formation of the metastable state, with a high predicted quantum yield of isomerisation (68%) in gas phase.
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- Pfeifer, L., et al.
(författare)
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Controlling forward and backward rotary molecular motion on demand
- 2022
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Synthetic molecular machines hold tremendous potential to revolutionize chemical and materials sciences. Their autonomous motion controlled by external stimuli allows to develop smart materials whose properties can be adapted on command. For the realisation of more complex molecular machines, it is crucial to design building blocks whose properties can be controlled by multiple orthogonal stimuli. A major challenge is to reversibly switch from forward to backward and again forward light-driven rotary motion using external stimuli. Here we report a push-pull substituted photo-responsive overcrowded alkene whose function can be toggled between that of a unidirectional 2(nd) generation rotary motor and a molecular switch depending on its protonation and the polarity of its environment. With its simplicity in design, easy preparation, outstanding stability and orthogonal control of distinct forward and backward motions, we believe that the present concept paves the way for creating more advanced molecular machines. Being able to control motion at the molecular level is vital for many future developments in the molecular sciences. Here, the authors report the controlled forward and backward rotation of a molecular motor guided by external stimuli.
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- Sips, F. L. P., et al.
(författare)
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Model-Based Quantification of the Systemic Interplay between Glucose and Fatty Acids in the Postprandial State
- 2015
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 10:9
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Tidskriftsartikel (refereegranskat)abstract
- In metabolic diseases such as Type 2 Diabetes and Non-Alcoholic Fatty Liver Disease, the systemic regulation of postprandial metabolite concentrations is disturbed. To understand this dysregulation, a quantitative and temporal understanding of systemic postprandial metabolite handling is needed. Of particular interest is the intertwined regulation of glucose and non-esterified fatty acids (NEFA), due to the association between disturbed NEFA metabolism and insulin resistance. However, postprandial glucose metabolism is characterized by a dynamic interplay of simultaneously responding regulatory mechanisms, which have proven difficult to measure directly. Therefore, we propose a mathematical modelling approach to untangle the systemic interplay between glucose and NEFA in the postprandial period. The developed model integrates data of both the perturbation of glucose metabolism by NEFA as measured under clamp conditions, and postprandial time-series of glucose, insulin, and NEFA. The model can describe independent data not used for fitting, and perturbations of NEFA metabolism result in an increased insulin, but not glucose, response, demonstrating that glucose homeostasis is maintained. Finally, the model is used to show that NEFA may mediate up to 30-45% of the postprandial increase in insulin-dependent glucose uptake at two hours after a glucose meal. In conclusion, the presented model can quantify the systemic interactions of glucose and NEFA in the postprandial state, and may therefore provide a new method to evaluate the disturbance of this interplay in metabolic disease.
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- Stindt, Charlotte N., et al.
(författare)
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Activating a light-driven molecular motor by metal complexation
- 2023
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Ingår i: Chem. - : CELL PRESS. - 2451-9308 .- 2451-9294. ; 9:8
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Tidskriftsartikel (refereegranskat)abstract
- Designing increasingly complex, responsive, and dynamic molecular systems, whose actions can be controlled by a combination of cooperative stimuli, is a key challenge toward the development of more advanced functional molecular machines. Herein, we report new photochemically driven molecular motors based on a bis(benzoxazole) ligand. Coordination of the ligand to a metal salt leads to the selective in situ activation of a well-defined motor function, which can be deactivated in the presence of a competing ligand. The rotation speed and absorption wavelength are tuned by the choice of metal, allowing unprecedented control of the molecular system. DFT calculations show that the geometry of the metal center influences the rotational barriers and the possibility to couple the rotary motion with the wagging movement at the metal center. The approach presented here will open new avenues toward more complex, dynamic, and coupled systems.
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