Design, synthesis and characterization of new luminescent crystalline materials

The research project could be divided in two main topics: (i) the structural and thermal characterization and the polymorph screening of a specific class of semiconducting organic materials: the 2,3-thienoimide (TI) based oligothiophenes; (ii) the synthesis and characterization of new luminescent coordination polymers based on d10 metal halides. The crystal structure determination was carried out both by Single Crystal X-ray diffraction and Powder X-ray diffraction. The 2,3-thienoimide (TI) based oligothiophenes present different crystalline forms that can be obtained by changing the solvent of recrystallization or combining deposition and annealing processes, so part of the work was also dedicated to the study of polymorphism and the analysis of the solid state transition between the different crystal phases. These molecules are characterized by a strong luminescence which dramatically changes depending on the polymorph, this behaviour makes the molecule interesting for potential application in OFET, OLET or TTI. The coordination polymers were obtained by solvothermal reaction, synthesis in solution and by direct grinding of the reagents. The mechanochemistry permits to perform the reaction directly in solid state, overcoming the intrinsic low solubility of Cu(I) and Ag(I) halides, and can yield crystal forms that are not obtainable in solution. However, in several cases the 1-D chain is due to the formation of infinite chain of CuI or AgX which make these compounds closer to the hybrid material than to coordination polymers.