Master or Internship Student: Mechanical reversibility of azide-alkyne cycloaddition reactions
Stellenangebot vom 4. Januar 2019
The cycloaddition between azides and alkynes has become a highly versatile conjugation reaction in biology and materials science, resulting from its high specificity and relatively fast kinetics. Recently it has been proposed that mechanical strain can 'catalyze' the reverse reaction, breaking the formed triazole ring into azide and alkyne starting materials (1). From a materials science point of view, this reversibility is highly interesting as it may serve as a starting point for the development of self-healing and self-reporting materials for a large number of different applications. Despite a growing number of simulations that strongly suggest the mechanical reversibility of triazole formation (1), experimental evidence for this reaction is still lacking. In this project you will utilize a combination of methods to obtain experimental proof that triazole rupture will liberate azide and alkyne functional groups.
You will investigate the mechanical response of different triazoles formed in the reaction of an azide with strained alkynes (1). You will use single molecule force spectroscopy to directly observe triazole rupture and to determine the force required for this reaction. In parallel, you will synthesize hydrogels that contain the triazole as a material crosslinker. Using non-linear rheology, you will observe the hydrogel response to an applied shear force and investigate possible triazole rupture. If bond rupture indeed generates the starting materials, released alkyne groups can be visualized using a fluorogenic azide reagent (2). Your results will serve as an important starting point for the further optimization of triazoles as mechanoresponsive molecular building blocks for the synthesis of smart materials.
You are studying chemistry, physics, nanotechnology or materials science. You are open and interested in learning new methods and applying them in an interdisciplinary context. We offer the possibility to participate in an ongoing, collaborative research project at an international research institute. Independent thinking, team spirit and communication are crucial for a successful development of the project. You should further have a good level of English.
(1) M. J. Jacobs, G. Schneider, K. G. Blank (2016) Mechanical Reversibility of Strain‐Promoted Azide-Alkyne Cycloaddition Reactions. Angewandte Chemie International Edition 55: 2899-2902
(2) M. Wirtz, A. Grüter, P. Rebmann, T. Dier, D. A. Volmer, V. Huch, G. Jung (2014) Two-color emissive probes for click reactions. Chemical Communications 50: 12694-12697