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Materials 2014, 7(3), 2030-2043; doi:10.3390/ma7032030
Article

Preparation and Chemical Properties of π-Conjugated Polymers Containing Indigo Unit in the Main Chain

1,* , 2
, 3
 and 2,*
Received: 19 January 2014; in revised form: 21 February 2014 / Accepted: 26 February 2014 / Published: 11 March 2014
(This article belongs to the Special Issue Conjugated Polymers)
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Abstract: π-Conjugated polymers based on indigo unit were prepared. Dehalogenative polycondensation of N-hexyl-6,6'-dibromoindigo with a zerovalent nickel complex gave a homopolymer, P(HexI), in 77% yield. Copolymer of N-hexyl-indigo and pyridine, P(HexI-Py), was also prepared in 50% yield. P(HexI) showed good solubility in organic solvents, whereas P(HexI-Py) was only soluble in acids such as HCOOH. The weight-average molecular weights (Mw) of P(HexI) and P(HexI-Py) were determined to be 10,000 and 40,000, respectively, by a light scattering method. Pd-catalyzed polycondensation between 6,6'-dibromoindigo with N-BOC (BOC = t-butoxycarbonyl) substituents and a diboronic compound of 9,9-dioctylfluorene afforded the corresponding alternating copolymer, P(BOCI-Flu), as a deep red solid in 98% yield. P(BOCI-Flu) was soluble in N-methyl-2-pyrroridone and showed an Mw of 29,000 in GPC analysis. Treatment of P(BOCI-Flu) with CF3COOH smoothly led to a BOC-deprotection reaction to give an insoluble deep green polymer, P(I-Flu), in a quantitative yield. Diffuse reflectance spectra of powdery P(BOCI-Flu) and P(I-Flu) showed peaks at about 580 nm and 630 nm, respectively, which are thought to originate from the indigo unit.
Keywords: π-conjugated polymer; indigo; polycondensation; H-chromophore π-conjugated polymer; indigo; polycondensation; H-chromophore
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Fukumoto, H.; Nakajima, H.; Kojima, T.; Yamamoto, T. Preparation and Chemical Properties of π-Conjugated Polymers Containing Indigo Unit in the Main Chain. Materials 2014, 7, 2030-2043.

AMA Style

Fukumoto H, Nakajima H, Kojima T, Yamamoto T. Preparation and Chemical Properties of π-Conjugated Polymers Containing Indigo Unit in the Main Chain. Materials. 2014; 7(3):2030-2043.

Chicago/Turabian Style

Fukumoto, Hiroki; Nakajima, Hisashi; Kojima, Takahiro; Yamamoto, Takakazu. 2014. "Preparation and Chemical Properties of π-Conjugated Polymers Containing Indigo Unit in the Main Chain." Materials 7, no. 3: 2030-2043.


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