Suzuki polycondensation . polymer conjugated

Fluorenylidene linkages have been widely used as conjugation interrupters due to their stiff conformation and to the ability to increase solubility of the resulting polymer and were therefore incorporated in several PPP based polymers by the Suzuki polycondensation reaction [127]. Following this concept a blue emitting polymer based on... 

Over the past two decades, Suzuki polycondensation has become one of the most efficient methods for the synthesis of conjugated polymers. As another important cross-coupling protocol, the Suzuki-Miyaura cross-coupling reaction was invented by Suzuki and co-workers in 1979 The scope of the Suzuki reaction for synthetic applications has been surveyed in several excellent reviews by Kotha, Lahiri, Kashinath, Miyaura and Fu. The Suzuki-Miyaura cross-coupling reaction provided deeper insights into how to connect two specific sp -hybridized C-atoms more efficiently and under milder conditions. The Suzuki-Miyaura cross-coupling reaction was first used by Schlueter et al. to prepare poly(para-phenylene)s. ... 

Since then, Suzuki polycondensation (SPC) has become one of the most powerful and widely used methodologies for the synthesis of conjugated polymers. 

We will provide a class of low bandgap polymers applied in BHJ PSCs that are synthesized by Suzuki polycondensation. This section cannot possibly cover all these different polymers. Emphasis will be placed upon important classes of conjugated polymers based on bridged phenylenes, for example poly(2,7-fluorene), poly(2,7-carbazole), and poly(2,7-dibenzosilole) based D-A conjugated polymers. 

As already briefly mentioned, easily the most obvious change regarding optical properties appears in the transition from the open-chain precursor polymers to the planarized PPP ladder polymers (LPPP). The primary single-stranded coupling product (a benzoyl-substituted polyphenylene) from a Suzuki-type polycondensation between an alkyl- or alkoxy-substituted 2,5-dibromo-1,4-dibenzoylbenzene derivative and 2,5-dihexyl-l,4-phenylenediboronic acid is colorless with an absorption maximum Amax of 264 nm [n-TT transition c = 39,000 L/(moI cm)l (19]. This absorption behavior supports the strongly twisted structure of the main PPP chain. The mutual distortion of the aromatic subunits reduces the conjugative interaction to a minimum, so that the typical electronic properties of a conjugated polymer are almost completely lost. 

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