Conjugated group 13/15 inorganic-organic hybrid polymers

• Applicant: Professor Dr. Holger Helten
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: since 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 401739196

In the last decades, conjugated polymers have been the subject of tremendous research activity due to applications in electronic and optoelectronic devices (OLEDs, OFETs, OPVs), for biomedical imaging, and sensory applications. In recent years, the focus has shifted towards the functionalization of conjugated polymers with inorganic main group elements. In particular, the incorporation of boron has led to novel hybrid macromolecules with intriguing properties and functions. The replacement of selected C=C units by their isoelectronic and isosteric B=N units in conjugated organic systems has emerged as a viable strategy to produce novel materials with structural similarities to their all-carbon congeners but in many cases fundamentally altered electronic features. This BN/CC isosterism approach has been particularly successfully applied to polycyclic aromatic hydrocarbons, but its application to polymer chemistry has only been scarcely explored. Furthermore, the incorporation of BP units, which are valence isoelectronic with BN and CC, into organic materials has been less well-studied, though the potential of the resulting BCP hybrid materials for electronic applications has been recognized quite recently. Polymers featuring BP linkages in the main chain are unknown thus far. The aim of this research proposal is the development of novel conjugated, cyclolinear polymers comprised of a backbone of organic building blocks and B=N or B=P units, respectively. Polymers with essentially linear B=N linkages are of particularly interest, as in such species possible conjugation along the polymer chain must occur through this unit because no alternative conjugation pathways exist. Exciting structural and electronic effects are expected to be observed also with polymers consisting of alternating heterocyclic building blocks of different aromaticity. The incorporation of electron-donor and -acceptor components via a modular approach will allow to effectively tune the electronic properties of the new materials. This will provide fundamental insight into the electronic interaction and communication over B=N and B=P units in linearly extended conjugated systems. In order to obtain well-defined materials, new controlled synthetic approaches to access such species under mild conditions, including (catalytic) AB type polycondensation and chain-growth routes. This may lead to living polymerization systems, which enable precise control over polymer architecture and offer the possibility to prepare block copolymers with potential for nanoscience applications.

• DFG Programme: Research Grants