Responsive Molecular Systems through Dynamic Covalent Chemistry

Time: Fri 2020-02-21 14.00

Location: F3, Lindstedtsvägen 26, Stockholm (English)

Subject area: Chemistry

Doctoral student: Antanas Karalius , Organisk kemi

Opponent: Professor Stefan Matile, University of Geneva

Supervisor: Zoltan Szabo, Kemi

Abstract

Nature tends to inspire research in chemistry. Systems that emerge from molecules interacting via reaction networks is something that life has mastered over the course of evolution in order to produce complexity. Dynamic reactions are key in systems chemistry, where reaction networks give rise to complex, emergent behavior. This thesis aims to harness a special feature of selected dynamic reaction systems – responsiveness.The first chapter of this thesis introduces dynamic covalent chemistry and a general approach to create simple reaction networks by connecting dynamic covalent reactions. Concepts in systems chemistry are introduced in terms of network topology, responsiveness and non-equilibrium processes, while drawing parallels to natural systems.The second chapter explores the potential of the nitroaldol reaction for dynamic systems. Nitroaldol reactions are demonstrated for dynamic polymerization as well as formaldehyde-responsive breakdown of dynamic polymers. The simultaneous formation and breakdown of polymers create emergent non-equilibrium behavior. Furthermore, nitroaldol produced-diols are used in boronate ester formation. This reactivity produces interdependence over two reactions. Combining nitroaldol and boronate building blocks enabled boronate dynamers of different topology.The third chapter explores metal coordination effects in dynamic reaction networks. Novel base-free nitroaldol reactivity is exploited in reaction networks with hemiacetals. A systemic response to metals is demonstrated by hemiacetal-metal coordination. In the second half of the chapter, a biomimetic dynamic imine complex is shown to produce emergent, π-π-interactions resembling a “draw-bridge”. Variation of metal charge, effective electrostatic character of substituent and ligands gives control over the system and its emergent π-π-interactions.

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