Synthesis of conjugated oligomers and polymers: the organometallic way

Abstract

Results of special interest in the field of organometallic\ud chemistry directed towards the synthesis of conjugated\ud oligomers and polymers are reviewed. Methodologies\ud widely employed in the synthesis of well-defined molecules\ud and based on the transition metal catalyzed coupling\ud reactions of various organometallic (B, Sn, Si, Mg and Zn)\ud reagents have been more recently extended to build up polyor\ud oligo-meric conjugated molecular architectures.\ud Although the focus of the present work is on transition\ud metal cross-coupling or homo-coupling processes, other\ud useful organometallic routes, such as metathesis reactions\ud and acetylene polymerization, have also been dealt with.\ud Owing to their higher versatility with respect to the nonorganometallic\ud processes commonly used for the synthesis\ud of these materials, the approaches presented allow the\ud realization of more complex molecular structures, which are\ud nowadays required in many electronic and optoelectronic\ud applications. The use of organometallic strategies has been\ud discussed from a synthetic organic chemist’s point of view,\ud and advantages and limitations of the different\ud methodologies reviewed have been highlighted. Some\ud attention has also been paid to the properties of the resulting\ud materials and to their dependence on the procedure\ud followed and the framework obtained

Intramolecular Hydrogen‐Bond‐Assisted Planarization of Asymmetrically Functionalized Alternating Phenylene–Pyridinylene Copolymers

“…[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] p-Conjugated polymers that incorporate aryl heterocyclic units, such as pyridine, pyrrole, and thiophene rings, have been synthesized and employed in industrial applications. [30][31][32][33][34] The laddertype polymers incorporated with pyrazines, [35] benzothiadazoles, [36] pyrroloimides, [37] pyridobisimidazoles, [38] and benzothiazole [39] that contain intramolecular hydrogen bonds along the polymer backbone are also known in the literature. One of the most important features of the pyridine-incorporated polymers is the high electron affinity of pyridine compared to phenylene-based polymers.…”

Development of catalyst‐transfer condensation polymerization. Synthesis of π‐conjugated polymers with controlled molecular weight and low polydispersity

“…[4][5][6][7] However, PATs synthesized in early work had no regioregularity of the alkyl group on the thiophene ring; there were three relative orientations (head-to-tail, head-tohead, tail-to-tail) in the coupling reaction. In 1992, McCullough and Lowe 8 and Rieke and Chen 9 independently reported the synthesis of regioregulated head-to-tail poly(3-hexylthiophene) (HT-PHT) by metal-catalyzed condensation polymerization of 5-metalated-2-bromo-3-hexylthiophene with Ni(dppp)Cl 2 or Ni(dppe)Cl 2 as a catalyst. The physical properties, such as electrical conductivity, light-emitting ability, and field effect mobility, of the obtained HT-PHT were superior to those of the regior-andom polymer.…”

“…This catalysttransfer condensation polymerization is generally applicable for the synthesis of polythiophene with an etheric side chain and poly(p-pheneylene), as well as for the synthesis of polyfluorene via the Pd-catalyzed Suzuki-Miyaura coupling reaction. V INTRODUCTION p-Conjugated polymers, which have been mainly synthesized via electrochemical polymerization 1 and organometallic condensation polymerization, 2,3 are an attractive class of materials due to their potential applications in electronic devices. Of these p-conjugated polymers, poly(3-alkylthiophene)s (PATs) have received much attention because of their environmental and thermal stability, good solubility, and high electrical conductivity.…”

Organometallic Approaches to Conjugated Polymers for Plastic Solar Cells: From Laboratory Synthesis to Industrial Production

“…[83] Regioregular poly(3-alkylthiophene)s (P3ATs) were initially prepared by McCullough and coworkers from 3-alkyl-substituted 2-bromothiophenes under cryogenic conditions [84] involving α-lithiation of the thiophene halide, subsequent transmetallation with MgBr 2 ·Et 2 O, and a final polymerization step in the presence of a catalytic amount of Ni(dppp)Cl 2 . A few years later, Grignard metathesis, or the GRIM method, was reported as a straightforward synthetic route to these polymers [85] (Scheme 32): a commercially available Grignard reagent is used in the metallation step to provide a mixture of regioisomeric organomagnesium derivatives (ratio 85:15), which then undergo Ni-catalyzed polymerization.…”