14:15-14:40: Aino Luukkonen
Title: Electronic and optical properties of small ligand protected gold complexes
Abstract: In this thesis, eight gold complex structures and their absorption spectra are studied using density functional theory (DFT) in two different calculation softwares; GPAW and Turbomole. The aim was to compare the two programs and benchmark the results from geometry optimization and UV-vis absorption spectra using the PBE functional. The results show that the geometries, bond lengths and angles of the structures are very similar in the output of both programs. The optical spectra is also similar but there is a noticeable blue shift in Turbomole’s result compared to GPAW. This comparison between programs was done because GPAW has long been the golden standard for this group. However, it has its limitations, one of which being the inability to calculate two photon absorption (TPA) spectra. TPA spectra was calculated in Turbomole for all eight structures using the cam-b3lyp functional. The structures with smaller ligands showed very high TPA cross sections compared to the bigger structures. The highest peaks are likely caused by the double resonance effect with one photon excitations. Overall, the locations of the peaks in TPA spectra correspond to the peaks in one photon absorption spectra, indicating the reliability of the results.
Supervisors: Hannu Häkkinen and Sami Malola
14:40-15:05: Anuruvi Lankage
Title: Co-linker Engineering of UiO-66 for Tuneable Structural Properties
Abstract: Metal Organic Frameworks (MOFs) offer a versatile platform for tailoring material properties through linker modification enabling applications like gas storage and separation. In this study UiO-66 framework was modified through incorporation of five different co-linkers to investigate how linker geometry, functionality and steric effects influence structural integrity and porosity. The materials were synthesized under varying conditions including co-linker ratios, modulator type and amount, synthesis temperature and precursor concentration to evaluate their impact on framework formation and stability. The results show that co-linkers with geometries closely matching the parent terephthalic acid linker were successfully incorporated while largely preserving crystallinity whereas bulkier and structurally complex linkers disrupted framework amorphization and reduced porosity as confirmed by surface area analysis indicating pore blockage and structural distortion. Thermal analysis further revealed that framework stability is strongly dependent on linker type, defect formation and post synthetic treatment. Spectroscopic analysis confirmed coordination bonding although distinguishing specific linker contributions was limited in some cases due to overlapping features. Overall study demonstrates that successful co-linker incorporation in UiO-66 requires a balance between functional modification and structural compatibility. Linker engineering provides a route to tune material properties but excessive deviation from the parent structure compromises crystallinity and porosity highlighting key considerations for the design of application specific MOFs.
Supervisors: Manu Lahtinen, Samu Forsblom, Jessy Joseph
