Dissertation: The impact of structural modifications on macrocyclic molecules in supramolecular chemistry (Pamula)
In her dissertation research, Malgorzata Pamula explored the role of noncovalent interactions, such as hydrogen bonding, π–π stacking, and anion–π interactions, in supramolecular systems and their effect on dynamic properties, molecular recognition, binding affinities, capsule formation, and efficient ion transport across a lipid bilayer.
“The research provides an important insight into supramolecular chemistry and will enable the design of more efficient supramolecular systems, which could be utilized in cancer treatment,” says grant researcher Malgorzata Pamula from the Ģֱ.
Assessing intramolecular interactions through structural modifications
Pamula synthesized and characterized supramolecular systems based on resorcinarenes and calix[4]pyrrole derivatives.
“By comparing different structural analogs,” says Pamula, “the studies aimed to assess the influence of structural features on intramolecular interactions and molecular flexibility, revealing how subtle structural modifications in macrocyclic molecules can significantly impact their behavior and function.”
Properties of the podands
The study focused on resorcinarene podands, macrocyclic molecules derived from resorcinol, functionalized to include podand arms capable of intramolecular interactions. The first podand features a sulfonyl group (-SO₂-) linking the tolyl ring to a 1,2-dioxyethane chain, while the second podand possesses a -CH₂O- linkage instead. The primary objective was to determine how the presence or absence of the sulfonyl group affects the conformational dynamics and self-inclusion properties of these podands.
“The obtained results revealed that the first podand adopts a boat conformation with self-inclusion of one podand arm into its aromatic cavity, stabilized by intramolecular interactions,” says Pamula. “In contrast, the podand with -CH₂O- linkage also exhibits a boat conformation but without self-inclusion, resulting in greater conformational flexibility.”
Hydrogen-bonded capsules
Pamula also aimed to understand the host–guest chemistry of aryl-extended and two-armed calix[4]pyrroles, focusing on their ability to form hydrogen-bonded complexes with various guest molecules, including cations, anions, and neutral molecules. Both NMR studies and DFT calculations showed that anions bind preferentially through exo-cavity interactions involving the upper rim hydroxyl groups of calix[4]pyrrole due to reduced structural distortion and favorable interactions. Furthermore, the formation of a dimeric hydrogen-bonded capsule with adiponitrile highlights its potential to encapsulate guest molecules within electron-rich cavity.
“When it comes to applications,” says Pamula, “aryl-extended calix[4]pyrroles can be used to bind anions from water by forming strong hydrogen bonds, effectively extracting them from aqueous solutions. ”
Malgorzata Pamula studied chemistry at Nicolaus Copernicus University and graduated with a master's degree from the Chemistry of Advanced Materials master’s program in 2014. During her graduate studies, she worked as a trainee and research assistant at the chemistry department of Lappeenranta University of Technology. Her doctoral research has been funded by the Research Council of Finland, the Emil Aaltonen Foundation, and the OLVI Foundation.
M.Sc Malgorzata Pamula will defend her PhD thesis “Diverse roles of noncovalent interactions in supramolecular systems based on resorcinarenes and calix[4]pyrroles” on 22.11.2024 at 12:00 at Ylistönrinne Campus in lecture hall KEM4. The opponent is Professor Enrico Dalcanale(Università di Parma, Italy) and the custos is Assistant Professor Kaisa Helttunen (Ģֱ).
The dissertation “Diverse roles of noncovalent interactions in supramolecular systems based on resorcinarenes and calix[4]pyrroles” can be read on the JYX publication archive:
