Hybrid coordination polymers based on silver halide and Ppicolylamine as new luminescent and conductive materials

This research studied new crystalline materials, specifically coordination polymers (CPs) based on silver halides and n-(aminomethyl)pyridine (n-pica, where n = 2, 3, 4). The study involved three key areas: 1. Synthesis and structural characterization: this part aimed to develop eco-friendly synthesis methods that minimize solvent usage and to explore the structural variety of silver halide-based CPs. Analysis in the Cambridge Structural Database showed that Ag(I) in AgXL compounds (where X is a halide and L an organic ligand) typically has tetrahedral coordination. Halide ions in these compounds exhibit many bridging patterns and coordination numbers, which enhance their structural diversity and enable the formation of hybrid coordination polymers (HCPs). Twelve different compounds were synthesized and structurally characterized during this Ph.D. project. 2. Polymorphic phases and stoichiometry: This part investigated the existence of different polymorphic phases and changes in stoichiometries in the synthesized compounds. Mechanochemical synthesis was a useful method to control the stoichiometry for compounds involving liquid ligands at room temperature as reactants. The study examined how stoichiometric ratios and small additions of a reactant affect reactions. Thermal treatment of [(AgX)(3-pica)]n showed varied behaviors based on the halide type, leading to phase transitions and the potential for forming solid solutions. 3. Photophysical and conductive properties: This segment analyzed the luminescent properties of [(AgX)(n-pica)]n, revealing their temperature-dependent behavior and the presence of thermally activated delayed fluorescence (TADF). DFT calculations helped clarify the influence of halides on these properties. Lastly, [(AgBr)₂(3-pica)]n was tested for its conductivity, both with electrochemical methods and terahertz spectroscopy, displaying semiconductor behavior according to the Drude model.