Functional Applications of the Mechanical Bond
Tuning Photophysical, Radiochemical and Biological Properties in Rotaxanes
Time: Thu 2026-11-19 10.00
Location: F3, Lindstedtvägen 26
Language: English
Doctoral student: Anja Ramström , Organisk kemi
Opponent: Professor Thorfinnur Gunnlaugsson, Trinity College Dublin
Supervisor: Universitetslektor Fredrik Schaufelberger, Organisk kemi; Professor Markus D. Kärkäs, Organisk kemi
Embargo t.o.m. 2027-11-19 godkänt av skolchef Amelie Eriksson Karlström via e-post 2025-10-20.
QC 2026-10-20
Abstract
The mechanical bond arises as a supramolecular consequence of physically interlocking two or more molecular components in the absence of a direct covalent linkage, analogous to links in a chain. Such mechanically interlocked molecules exhibit unique co-component structural dynamics that are unachievable in rigid, covalent scaffolds. While these interlocked architectures historically enabled the development of artificial molecular machines, this thesis aims to expand the fundamental understanding of the effect of the mechanical bond in diverse interdisciplinary applications across biological, photophysical, synthetic, and coordination chemistry.
To overcome challenges in designing efficient and responsive sensing platforms in traditional, covalently grafted systems, a novel class of interlocked lanthanide chelates was developed. This architecture exploits through-space energy transfer via the mechanical bond, enabling modulated photophysical and chiroptical properties of the lanthanide centers – including circularly polarized luminescence – while providing a dynamic cavity for selective cation recognition. To extend this platform to nuclear medicine, radiolabeled analogues were developed to provide a systematic evaluation of how the mechanical bond influences complexation kinetics, kinetic lability, radiotracer biostability, and pharmacokinetic clearance pathways in vivo. Beyond coordination chemistry, the spatial constraint induced by the mechanical bond was leveraged as a synthetic tool to kinetically trap a reactive organometallic intermediate, unlocking previously inaccessible cross-coupling reactivity. Finally, a stimuli-responsive mechanical bond was introduced as a non-covalent strategy to silence peptide (bio)functions, where targeted cleavage upon a specific stimulus restores native structure and function. Together, these findings demonstrate the mechanical bond as a versatile, fundamental design element for advanced functional applications.