Synlett 2018; 29(20): 2660-2668
DOI: 10.1055/s-0037-1611310
cluster
© Georg Thieme Verlag Stuttgart · New York

Direct C–H Arylation Polymerization to form Anionic Water-Soluble Poly(3,4-ethylenedioxythiophenes) with Higher Yields and Molecular Weights

a  Smart Organic Materials Laboratory, Institute of Chemistry, Academia Sinica, Nankang, 128 Academic Road, Sec. 2, Taipei 115, Taiwan
b  Taiwan International Graduate Program (TIGP), Sustainable Chemical Science and Technology (SCST), Academia Sinica, Taipei 115, Taiwan
c  Department of Applied Chemistry, National Chiao Tung University, Hsinchu 300, Taiwan
,
Tian-lin Wang
a  Smart Organic Materials Laboratory, Institute of Chemistry, Academia Sinica, Nankang, 128 Academic Road, Sec. 2, Taipei 115, Taiwan
,
Tsai-Hui Wang
d  Department of Chemistry, Tamkang University, New Taipei, Taiwan   Email: bruceyu@gate.sinica.edu.tw
,
Hsiu-Fu Hsu
d  Department of Chemistry, Tamkang University, New Taipei, Taiwan   Email: bruceyu@gate.sinica.edu.tw
,
a  Smart Organic Materials Laboratory, Institute of Chemistry, Academia Sinica, Nankang, 128 Academic Road, Sec. 2, Taipei 115, Taiwan
b  Taiwan International Graduate Program (TIGP), Sustainable Chemical Science and Technology (SCST), Academia Sinica, Taipei 115, Taiwan
› Author Affiliations

This research was supported by the Ministry of Science and Technology (MOST) of Taiwan (MOST-106-2628-M-001-001-MY3 and MOST-106-2627-M-001-011). This project was also supported by the Academia Sinica Research Project on Nano Science and Technology and Academia Sinica Thematic Project. H.A. thanks the Taiwan International Graduate Program (TIGP) for a Ph.D. fellowship.
Further Information

Publication History

Received: 04 October 2018

Accepted after revision: 08 October 2018

Publication Date:
28 November 2018 (online)


Abstract

A facile and environmentally benign Pd-catalyzed direct C–H arylation polymerization (DAP) has been developed for the syntheses of homo- and copolymers of anionic-group-functionalized 3,4-ethylenedioxythiophenes with high yields (up to 99%), high molecular weights, and narrow polydispersities. The effects of various Pd catalysts, phosphine ligands, and additives on the properties of the polymers have been examined. The method gives anionic poly(3,4-ethylenedioxythiophenes) with higher molecular weights than those produced by the previously reported chemical or electrochemical methods. The method was also used to synthesize polymers functionalized with carboxylic acid groups without the need for protection/deprotection steps. The resulting polymers can be processed from water or highly polar organic solvents. We also demonstrated a phosphine-free, water-mediated, Pd-catalyzed DAP. The anionic poly(3,4-ethylenedioxythiophenes) were stable in water, and are promising for applications in sensors, drug delivery, and cell engineering.

Supporting Information

 
  • References and Notes

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  • 19 Poly(C2-, C5-, and C12-EDOT-COOH) Polymers; General ProcedureThe polymerization process was similar to that of PEDOTS synthesis by direct C–H arylation polymerization. A N2-filled 50 mL Schlenk flask was charged with the appropriate EDOT-COOH and 2,5-dibromo-substituted EDOT-COOH monomers, Pd(OAc)2 (10 mol%), P(p-tol)3 (10 mol%), Cs2CO3 (4 equiv), and anhyd DMF. The mixture was stirred for 36 h at 90 °C, then cooled. The reaction was then quenched with 1:1 H2O–MeOH, and excess acetone (40 mL) was added. The resulting suspension was centrifuged (5 min, 5000 rpm) and the resulting precipitate was dissolved again in 1:1 H2O–MeOH and precipitated with acetone. This procedure was repeated until a clear solution was obtained. The precipitate was then dried under vacuum and the product was characterized by means of 1H NMR and FTIR spectrometry.In agreement with previous reports, the 1H NMR spectra of the polymers showed broad peaks that were well observed in the zoom mode.Poly(C2-EDOT-COOH)Dark-blue solid; yield: 140 mg (79%). IR (KBr): 3653–3219 (weak br, OH of acid group), 2915 (weak br, C–H of alkyl groups), 1595 (strong, C=O of carbonyl group), 1519 (strong, C=C of thiophene ring), 1371 (strong, C–C stretching of alkyl groups), 1083 and 1039 cm–1 (medium bands; asymmetric and symmetric stretching of C–O–C, respectively).Poly(C5-EDOT-COOH)Blue solid; yield: 145 mg (75%). IR (KBr): 3666–3209 (weak br, OH of acid group), 2930 (weak br, C–H of alkyl groups), 1731 and 1648 (strong, C=O group stretching of ester and acid groups, respectively), 1519 and 1368 (strong, C=C of thiophene ring and alkyl C–C stretching, respectively), 1100 and 1055 cm–1 (medium bands of asymmetric and symmetric stretching of C–O–C, respectively).Poly(C12-EDOT-COOH): Purple solid; yield: 190 mg (89%). IR (KBr): 3652–3223 (weak and broad, OH of acid group), 2923 and 2852 (strong, C–H of alkyl groups), 1738 and 1657 (strong, C=O stretching of ester and acid groups, respectively), 1569 and 1371 (strong, C=C of thiophene ring and C–C of alkyl stretching, respectively), 1101 and 1051 cm–1 (medium bands of asymmetric and symmetric stretching of C–O–C, respectively).
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