Helicate-based cation triggered molecular springs
Chen, Xiaofei; Albrecht, Markus (Thesis advisor); Oppel, Iris Marga (Thesis advisor)
Dissertation / PhD Thesis
Dissertation, RWTH Aachen University, 2019
Several alkyl bridged bis(catecholketone or catecholester) ligands are designed and made in order to obtain helicates which cations triggered show some spring type dynamic motions.Within the helicates, in the presence of lithium cations the compressed coordination compound is formed, in which lithium cations are bound in the interior of the helicate. If those cations are removed by addition of [2.1.1]cryptand, the helicates expand due to repulsion between the negatively charged titanium triscatecholate units. Thus the helicates show a lithium ion triggered spring type motion. In addition, when the introducing chiral units into helicates, reversible switching is not only possible between those two states, furthermore, the twist of the aggregate also can be controlled. Thus, three out of four possible states of a helicate (expanded/left-handed, expanded/right-handed, compressed/left-handed) based on an enantiomerically pure ester bridged dicatecholate ligand are specifically addressed by introduction, exchange, or removal of countercations.