Mikroporöse organische Polymere auf Basis tetraedrischer Monomere der Gruppe IV

Abstract

In this thesis, porous organic polymers were synthesized on the basis of tetrahedral monomers of the group IV. Their optical properties and porosities were investigated and specifically tuned by the choice of monomers, reaction conditions or by postmodification. First, a tetrahedral, silicon-centered monomer with terminal bromides was employed for the Yamamoto homocoupling (Scheme 1, left). The alkyne functionalities at the central atom allow for the cleavage of the silicon-carbon-bond, after which the organic fragments of the insoluble network were identified. The results were compared to a formally structural identical material that was synthesized via an alternative synthesis route. Furthermore, tetrakis(4-ethynylphenyl)stannane was employed in a screening under Sonogashira- Hagihara conditions (Scheme 1, right). Fluorescence and porosity of the formally identical networks were dependent on the chosen reaction conditions. The materials were cleaved at the tin-carbon bonds with chloroacetic acid to analyze the organic linkers and examine the completeness of the polymerization. In addition, networks were screened for the influence of the central atom in the tetrahedral monomer. The elements of group IV (M = C, Si, Ge, Sn) were used as central units. Irrespectively of the applied conditions, the carbon-centered materials revealed the highest BET surface areas whereas the tin-centered ones yielded the lowest. Nevertheless, the absolute dimension of the surface area is related to the chosen synthesis protocol. Moreover, postmodification of porous polymers derived from AA’-polymerization of varying amounts of silicon- and tin-centered monomers was realized. They were selectively cleaved at the tin-carbon bonds to release fractions of the linkers and to tune porosity and emission color. Finally, sulfur containing polymers were synthesized from tetrakis(4-ethynylphenyl)silane for implementation as cathode material in lithium sulfur batteries. The networks showed moderate activities with capacities up to 750 mAh/g.