Ģ��ֱ��

Supramolecular chemistry studies weak interactions which can be applied in spontaneous self-assembly into larger entities. Studying the structural properties of these supramolecular complexes, Taipale has employed single crystal X-ray crystallography which allowed to gain substantial information on the weak interactions, such as hydrogen and halogen bonding. The dissertation brought new information on the utilization of supramolecular interactions in the modulation of fluorescence and on the relatively new concept of the supramolecular chemistry of the iodine(I) (iodonium) complexes.

In the first part of her dissertation, Taipale studies the effect of different acids on the photochemistry of simple quinoline and carbazole derivatives. These compounds are small molecules containing nitrogen atoms that are easily modified with different functional groups to be suitable for various purposes. By adding a small amount of acid to a carbazole compound, and forming a hydrogen bond within the system, remarkable increases in the fluorescence quantum yield were observed from 16% to 80% in solution and from 1% to 49% in the solid state, which for these compounds without dopants is rare. The dissertation gave insightful information on the design of fluorescent materials and altering their properties using weak interactions. Fluorescent materials are utilized in many applications, such as sensors or OLED-lights.

In the second part of her dissertation, Taipale studied halogen bonding, which is similar to a hydrogen bonding, however, a newer less studied interaction. Exceptional iodine(I) structures, and their analogous silver(I) structures, were studied by forming positively charged silver(I) [N–Ag–N]+ complexes which were further reacted into iodine(I) [N–I–N]+ complexes via a cation exchange reaction. The progression of intermolecular recognition and assembly was monitored using NMR spectosccopy in solution and the resulting structures were studied using single crystal X-ray crystallography in the solid state. Since especially iodine(I) bonds are known to be extremely linear, the interactions are predictable and can be employed in the design and construction of larger supramolecular entities. These results were utilized further by constructing larger cage-like structures from similar building blocks via self-assembly. The cages can be used to bind negatively charged small molecules. These experiments gave valuable information on a relatively new field of supramolecular chemistry, helped establish iodine(I) bond as a useful tool in supramolecular chemistry which can be applied in the design of new halogen-bonding materials.

The dissertation is published in JYU Dissertations series, number 496, Jyväskylä 2022. ISBN 978-951-39-9039-8 (PDF), URN:ISBN:978-951-39-9039-8, ISSN 2489-9003. Link to publication:

M.Sc. (Tech) Essi Taipale defends her doctoral dissertation “Synthetic and Structural Studies on the Effect of Non-Covalent Interactions on N(sp2)-Heterocyclic Molecules” on Friday 25 February at 12 noon. Opponent Professor Risto Laitinen (University of Oulu) and Custos Professor Kari Rissanen (Ģ��ֱ��). The doctoral dissertation is held in Finnish.

The audience can follow the dissertation online.
Link to the online event: 

Phone number to which the audience can present possible additional questions at the end of the event (to the custos): +358 50 562 3721