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Indacenodithiophene Homopolymers via Direct Arylation: Direct Polycondensation versus Polymer Analogous Reaction Pathways
journal contribution
posted on 2019-09-19, 13:44 authored by Desiree Adamczak, Hartmut Komber, Anna Illy, Alberto D. Scaccabarozzi, Mario Caironi, Michael SommerIndacenodithiophene
(IDT)-based materials are emerging high-performance
conjugated polymers for use in efficient organic photovoltaics and
transistors. However, their preparation generally suffers from long
reaction sequences and is often accomplished using disadvantageous
Stille couplings. Herein, we present detailed synthesis pathways to
IDT homopolymers using C–H activation for all C–C coupling
steps. Polyketones are first prepared by direct arylation polycondensation
(DAP) in quantitative yield and further cyclized polymer analogously.
This protocol is suitable for obtaining structurally well-defined
IDT homopolymers, provided that the conditions for cyclization are
chosen appropriately and that side reactions are suppressed. Moreover,
this polymer analogous pathway gives rise to asymmetric side-chain
patterns, which allows one to fine-tune physical properties. Alternatively,
IDT homopolymers can be obtained via oxidative direct arylation polycondensation
of IDT monomers (oxDAP), leading to IDT homopolymers with similar
properties but at reduced yield. Detailed characterization by NMR,
IR, UV–vis, and PL spectroscopy, and thermal properties, is
used to guide synthesis and to explain varying field-effect transistor
hole mobilities in the range of 10–6–10–3 cm2/(V s).