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Doctoral defence of Diana Temer MSc, 1.12.2023: Unveiling photophysical properties and light-induced transformations of imidazolyl-based diimine derivatives

The doctoral dissertation in the field of Chemistry will be examined at the Faculty of Science, Forestry and Technology, Joensuu Campus.

What is the topic of your doctoral research? Why is it important to study the topic?

Light-matter interactions are essential in our daily lives and in emerging advanced technologies. Basic photophysical processes, including light absorption, conversion, generation, and transmission, find broad applications in various materials, analytical methods, information technologies, and medical tools. Additionally, these interactions lead to photochemical reactions, expanding the field of photochemistry. 

In my dissertation, I examine the design and synthesis of new phenanthro-diimine compounds, aiming to develop novel luminophores with tunable optical properties through metal binding and structural modification. This research facilitates a comprehensive understanding of the structure-property relationships in molecular materials. 

Furthermore, the study of metal-containing derivatives (metal complexes) provides a pathway to achieve new optical characteristics and reactivity, expanding the possibilities for the development of materials with tailored photophysical and photochemical properties. This understanding can lead to the design of more efficient and effective materials with improved stability and performance, thereby contributing to advancements in various industrial and scientific applications.

What are the key findings or observations of your doctoral research?

The study of emissive diimine ligands led to the discovery of unique properties, such as room temperature phosphorescence (RTP) in zinc metal complexes, which is a rare phenomenon. Additionally, the ligands exhibit mechanoresponsive behaviour, meaning they change their colour upon mechanical stimuli. The synthesis of novel cationic diimine ligands and the preparation of hybrid organic-inorganic complexes of zinc, cadmium, and lead further emphasized the distinctive optical properties and structures of these compounds. The exploration of novel chromophoric systems with photochromic properties (a reversible change of colour upon exposure to light), specifically the observation of photoinduced aryl transfer from the imidazole to the quinoline motif, a reversible process occurring under ambient conditions without a catalyst. 

These findings provide insights into the development of new photofunctional coordination compounds. The implementation of these research findings is valuable for the scientific community as it expands the understanding of the photophysical and photochemical properties of various chromophores and their metal complexes. The discovery of rare phenomena, such as room-temperature phosphorescence and photoinduced aryl transfer, contributes to the development of knowledge in the field.

Additionally, the tunable physical and chemical properties of the synthesized species offer diverse possibilities for the improvement of molecular materials with versatile photophysical properties, which can potentially lead to the creation of new materials for various practical applications. 

How can the results of your doctoral research be utilised in practice?

The compounds designed in the research could find applications in the development of efficient optoelectronic devices, such as organic light-emitting diodes (OLEDs), organic solar cells, and photodetectors. Their tunable optical properties and unique photophysical characteristics make them suitable candidates for enhancing the performance and efficiency of these devices. 

Also, compounds' ability to undergo changes of optical properties in response to external stimuli, such as mechanical and thermal factors, could enable the creation of highly sensitive and responsive sensors such as environmental monitoring and medical diagnostics. Furthermore, phenanthro-diimine compounds are potential candidates for biomedical imaging applications. They could be utilized in fluorescence imaging techniques, aiding in the visualization of specific biological processes or structures.

What are the key research methods and materials used in your doctoral research?

The doctoral research involves a combination of organic synthesis techniques, spectroscopic analysis, crystallography, and collaboration with external research partners for photophysical measurements and computational analyses. The synthesis of the oxygen-sensitive compounds was conducted under a nitrogen atmosphere. The synthesized compounds underwent comprehensive analysis using a set of standard physical techniques, including nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopy, UV–visible (UV-vis) absorption spectroscopy, single crystal and powder X-ray diffraction studies, mass spectrometry (MS), and CHN elemental analysis. Photophysical measurements include optical parameters such as UV-Vis absorption, excitation and emission spectra, excited-state lifetimes, and emission quantum yields. Computational analyses of the electronic structures were conducted to gain insights into the compounds' electronic properties and optical behavior.

The doctoral dissertation of Diana Temer, MSc, entitled Unveiling photophysical properties and light-induced transformations of imidazolyl-based diimine derivatives  will be examined at the Faculty of Science, Forestry and Technology, Joensuu Campus. The opponent will be Professor Kari Rissanen, University of Jyväskylä, and the custos will be Professor Igor Koshevoy, University of Eastern Finland. Language of the public defence is English.

For more information, please contact: 

MSc, Diana Temer, diana.temerova@uef.fi