Synthesis and Properties of Regioregular Poly(3-substituted thiophene) Bearing Disiloxane Moiety in the Substituent. Remarkably High Solubility in Hexane

Abstract

Regioregular poly(3-substituted thiophene) derivative bearing pentamethyldisiloxane moiety at the 3-substituent is prepared by nickel-catalyzed polymerization reactions with dehydrobrominative or debrominative generation of the organometallic monomer. The monomer precursors 2-bromo-3-(4pentamethyldisiloxybutan-1-yl)thiophene (1a) and 2,5-dibromo-3-(4-pentamethyldisiloxybutan-1-yl)thiophene (1b) are prepared from 3-methylthiophene with 45 steps in overall good yields. Treatment of 1a with TMPMgCl¢LiCl at room temperature for 3 h forms an organometallic monomer and following the addition of a nickel catalyst affords the corresponding polythiophene bearing a disiloxane moiety in the side chain. The reaction of 1b with Grignard reagent leads to the similar monomer and addition of a catalytic amount of [NiCl 2 (dppe)] also affords polythiophene in highly regioregular manners. The obtained polythiophene is found to be dissolved in a hydrocarbon such as hexane.

Synthesis of block copolymers comprised of poly(3‐hexylthiophene) segment with trisiloxane side chains and their application to organic thin film transistor

“…Mori and coworkers reported the synthesis of regioregular polythiophene derivatives having soft siloxane units in the side chains . Indeed, the films of siloxane‐containing polythiophenes showed 2 orders of magnitude smaller Young's modulus and 20 times higher elongation at break than P3HT.…”

A formal preparation of regioregular and alternating thiophene−thiophene copolymers bearing different substituents

“…Polymerization was carried out with standard Schlenk technique under a nitrogen or argon atmosphere. 1 H NMR (400 MHz), 19 F NMR (376 MHz) and 13 were purchased and used without further purification. Preparation of chlorobithiophene 4a and 4b was performed in a manner reported previously.…”

“…Two remarkable peaks were observed in 2θ = 3.94° and 12.18°, respectively, as shown in Fig 2 (a). The result suggests that the thin film of the alternating copolymer 6c shows bilayer lamellar structure involving 7.3 Å and 22.4 Å distances, respectively, 13,29,30 (Fig 2(b)) The molecular modeling of the alternating copolymer 6c suggests the chain lengths of 11.6 Å and 2.2 Å, respectively. The values of the observed layer distances of copolymer 6c closely corresponds to the twice values 11.6 x 2 and 2.2 x 2 (Fig 2(c) In summary, we have shown that formal alternating thiophene−thiophene copolymers were synthesized when a differently-substituted halobithiophene was employed as a monomer by nickel-catalyzed deprotonative polymerization was applied.…”

“…10,11 We have also engaged in the design of the side chain of polythiophenes and several functionalities have been successfuly introduced. [12][13][14] Our further concern is turned to the copolymerization of thiophene employing differently substituted thiophene monomers, with which several copolymerizations are plausible to give thiophene/thiophene copolymers of random 15 (statistical), gradient, 16,17 block, 18,19 alternating, 20-23 etc. 24,25 We are thus interested in the preparation of alternating polythiophene bearing two kinds of different substituent.…”

“…hexyl-5-(3-methylthiophen-2-yl)thiophene (4a):25 92% yield as a light yellow oil 1. H NMR (500 MHz, CDCl3) δ 0.92 (t, J = 7.5 Hz, 3H), 1.31-1.43 (m, 6H), 1.58-1.67 (m, 2H), 2.37 (s, 3H), 2.59 (t, J = 7.5 Hz, 2H), 6.83 (s, 1H), 6.87 (d, J = 5.0 Hz, 1H), 7.14 (d, J = 5.0 Hz, 1H) 13. C{ 1 H} NMR (100 MHz, CDCl3) δ 14.2, 15.3, 22.8, 28.2, 29.1, 29.7, 31.8, 123.5, 124.0, 126.2, 130.6, 131.4, 133.1, 134.2, 139.8.…”