The first year of the project was dedicated to synthesis of different free-based macrocyclic cores, organic ligands and metallocomplexes based on combining of parent core with peripheral substituents. A series of substituted isomers of metallocomlexes of porphyrazine, porphyrin, phthalocyanine and porphycene as well as pincer metallocomplexes were successfully synthesized.
The photophysical/spectroscopic data for selected new metallocomplexes were gathered during second year of the project. Performed work obeys systematic investigations of the conformational structures and stability of metallocomplexes in different media (crystal, metal surface, solution or polymeric films). MMCs with simplest chemical structure exhibit in solution stable and reproducible spectral and photophysical characteristics. It is worth to mention that the conformational stability and the photophysical properties of MMCs depend significantly on various of internal and external reasons. The modification of the structure with different substituents, ligands coordination to the central metal atom or essential distortion of the MMCs macrocycle in dependence on type of central metal ion are internal factors influencing the chemical structure of mentioned compounds. The external factors are: solvents properties (viscosity, polarity, hydrogen bonding), interaction with metallic surfaces, steric hindrance in polymeric films or temperature and pressure. In result, the structure and symmetry of the MMC may be essentially disturbed what, in consequence, can lead to modification of spectral and photophysical characteristics. Influence of all the types of factors on conformational stability and structure of MMCs were studied during second year of the project.
During the third year of the project, theoretical chemists performed mutual quantum chemical modeling of the tetrapyrrolic cores topology in dependence on substituents in order to understand the effect of different modifications of the cores geometry on the electronic properties of the singlet and triplet excited states of the MMCs. For example, the dependence of photophysical properties of novel palladium metallocomplexes was studied for series of octaethylporphyrins with increasing number of aryl substituents.
The last year of the project was dedicated to selection of functionalized MMCs suitable for various applications such as optical sensors and OLEDs.
In particular, a range of MMCs based on matalloporphirines and metallophthalocyanines along with organo-transition metal complexes were investigated. Several promising materials for application as optical sensors of temperature and oxygen were identified. Long excited state lifetimes make some of these materials promising agents for singlet oxygen generation - a phenomenon crucial for modern photodynamic treatment schemes for instance for cancer. A new class of metal complexes displaying efficient thermally activated delayed fluorescence at ambient temperature was found. These silver complexes display the shortest TADF luminescence times so far found for TADF materials and deliver compounds with photoluminescence quantum yields approaching unity. Thus, this class of coumpounds represents particularly attractive materials for OLED applications.
