Soft group 13/15 organic-inorganic hybrid materials

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This project proposal consists of two parts aimed at the development of pi-conjugated hybrid materials containing organic building blocks and inorganic main group elements in one framework. The objective of the first part is the preparation of novel pi-conjugated, linear polymers derived from well-established semiconducting organic polymers such as poly(p-phenylenevinylene) (PPV), polyacetylene (PA), or poly(p-phenylene) (PPP), in which specific C-C units of the backbone are replaced by isoelectronic B-N or B-P units. Preliminary computational studies predict that such systems show extended pi-electron delocalization along the main chain. Particularly interesting structural and electronic effects are expected to be observed with polymers consisting of alternating heterocyclic building blocks of different aromaticity. In order to obtain well-defined materials, new and mild synthetic procedures will be developed such as ring-opening polymerizations (ROP) of previously unknown BN- and BP-bridged paracyclophanes. It will be attempted to generate living polymerization systems, which enable precise control over polymer architecture and offer the possibility to prepare block copolymers with potential for nanoscience applications.The aim of the second part of this project is to develop novel molecular dyes with specifically tailored optical and electronic properties. Target systems are macrocycles having boron and nitrogen or boron and phosphorus centers in the meso positions of porphyrinoid and subporphyrinoid frameworks. These species are designed to feature a macrocyclic conjugated, aromatic 18- or 14-pi-electron system. Preliminary Time-Dependent DFT calculations reveal that this concept may lead to materials with potentially intriguing photophysical properties. Furthermore, unusual coordination abilities may arise. In addition to their potential for application in organic photovoltaics, gaining access to the novel macrocycles may help to answer fundamental questions such as to what extent can different main group elements communicate over extended pi systems, in particular, within a macrocyclic conjugated porphyrinoid or subporphyrinoid framework.