Synthesis of Thiophene- and Bithiophene-Based Alternating Copolymers via Pd-Catalyzed Direct C–H Arylation

Abstract

Polycondensation via direct C–H arylation of thiophene derivatives gave thiophene- and bithiophene-based alternating copolymers in good yields. The optimization of the reaction conditions was investigated in terms of a catalytic system and reaction time. Under optimized conditions, the polycondensation reaction of 3,3′,4,4′-tetramethylbithiophene with 2,7-dibromo-9,9-dioctylfluorene gave poly[2,7-(9,9-dioctylfluorene)-alt-5,5′-(3,3′,4,4′-tetramethyl-2,2′-bithiophene)] with a molecular weight of 31 800 in 91% yield. The polycondensation reaction proceeded with 2 mol % of Pd(OAc)2 without the addition of a phosphine ligand in a short reaction time (3 h). Six kinds of π-conjugated polymers were synthesized by the polycondensation reaction without the use of bifunctional organometallic reagents as monomers.

Direct Arylation Polycondensation of Thienothiophenes with Various Dibromoarylenes

“…16 Since precipitation of the polymer occurred during the reaction, the reaction was subsequently performed under diluted conditions (Entry 2). A relatively high molecular weight and yield were obtained at the concentration of 0.15 M. It should be noted that the highmolecular-weight polymer was obtained in 3h with only 2 mol % of a Pd precatalyst without a phosphine ligand which…”

“…9,2628 The reaction with 3,6-dinonylthieno[3,2-b]-thiophene afforded a corresponding polymer (Polymer 1) with a molecular weight of 17800 in 83% yield under the previously reported conditions (Table 1, Entry 1). 16 Since precipitation of the polymer occurred during the reaction, the reaction was subsequently performed under diluted conditions (Entry 2). A relatively high molecular weight and yield were obtained at the concentration of 0.15 M. It should be noted that the highmolecular-weight polymer was obtained in 3h with only 2 mol % of a Pd precatalyst without a phosphine ligand which is often essential for Pd-catalyzed cross-coupling reactions.…”

“…59 The development of direct arylation polycondensation has allowed use of various monomers such as alkylated thiophenes, 10,11 ethylenedioxythiophene, 12,13 thienopyrroledione, 14,15 bithiophenes, 16,17 bithiazoles, 18,19 benzodithiophenes, 20 pyrroles, 21 and fluorinated benzenes. 22,23 Expansion of the range of applications of direct arylation polycondensation is important for it to be a reliable method for preparing materials for use in organic optoelectronic devices such as organic photovoltaics (OPV), organic light-emitting diodes (OLED), and organic field-effect transistors (OFET).…”

Enwrapping Conjugated Polymer Microspheres with Graphene Oxide Nanosheets

“…6 Thus, an alternating copolymer 1, comprising 9,9-dioctylfluorene (F8) and 2,3,7,8-tetramethylbithiophene ( Figure 1a, left), 7 was dissolved in CHCl 3 (2 mL, [1] = 1 mg mL ¹1 ) and MeOH vapor was allowed to slowly diffuse into the solution. Microspheres were exclusively precipitated after being aged for 3 days at 25°C.…”

Synthesis of π-conjugated poly(thienylenearylene)s with nickel-catalyzed C–H functionalization polycondensation

“…The use of Hermann's catalyst with an appropriate phosphine ligand has been shown to be key for the remarkable catalytic activity that results in successful polymerization. In addition, Kuwabara, Kanbara, and their co-workers 18,19 recently reported the synthesis of thiophene-based alternating copolymers through direct C-H coupling by applying Fagnou's protocol. 20 We have also reported that nickel-catalyzed dehydrobrominative polycondensation takes place by the deprotonation at the C-H bond of the thiophene derivatives with the Knochel-Hauser base and chloromagnesium 2,2,6,6-tetramethylpiperidide lithium chloride salt (TMPMgCl Á LiCl).…”