Synthesis and characterization of novel low band-gap polymers containing squaraine units

Huo, Erfu; Wu, Jiang; Song, Bao Feng; Li, Ying; Jiang, Qing; Xie, Ming Gui

doi:10.1016/j.cclet.2007.09.037

Cited by 11 publications

(6 citation statements)

References 13 publications

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“…Later, it was Havinga et al who suggested that, by alternation of conjugated electron-donor and electron-acceptor moieties, small-band-gap polymers could be obtained. − This idea was also supported by theoretical considerations of Brocks et al, who proposed low band gaps in polysquaraines . Havinga et al proved this concept, using benzo(1,2-4,5)-di(1-alkyl-2-methylene-3,3-dimethylpyrroline), benzo(1,2–4,5)-di(3-alkyl-2-methylenethiazole), or terthiophene units as donors in the reaction with squaric acid to yield polymers with band gaps of ∼1 eV. − However, especially in the field of pyrrole-derived squaraine dyes, there is an ongoing effort to decrease the band gap, using variously substituted pyrrole derivatives. − Those studies have further been extended, using electron-donating bridging units such as 2,5-divinylthiophene between the squaraine dyes, thus forming copolymers . Even more popular is the use of 1,4-dialkoxydivinylbenzene bridging units.…”

Section: Introductionmentioning

confidence: 94%

“…46−48 Those studies have further been extended, using electron-donating bridging units such as 2,5-divinylthiophene between the squaraine dyes, thus forming copolymers. 49 Even more popular is the use of 1,4dialkoxydivinylbenzene bridging units. Low-band-gap polymers (∼1 eV) with a strong and broad absorption in the NIR region near ∼1000 nm were obtained, showing intrinsic conductivities of ∼10 −5 S cm −1 .…”

Section: ■ Introductionmentioning

confidence: 99%

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Exciton Coupling Effects in Polymeric cis-Indolenine Squaraine Dyes

Völker¹,

Lambert²

2012

Chem. Mater.

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Dicyanovinylene-substituted cis-indolenine squaraines were polymerized by a Ni-mediated Yamamoto homocoupling reaction. Preparative recycling GPC was used to obtain polymer fractions with different molecular weight distributions in order to investigate the influence of molecular weight on the optical properties. In this attempt, conjugated cyclic trimers could also be isolated that are, to the best of our knowledge, the first of their kind. These trimers and the squaraine polymers were investigated by cyclic voltammetry, absorption spectroscopy, and static and time-resolved fluorescence spectroscopy. While the trimers show multiple fluorescence bands with, for squaraines, an exceptional huge Stokes' shift, the polymers show broad absorption in the red to near infrared (NIR) region with narrow fluorescence and only the common minor Stokes' shift. The spectral features of the squaraines were interpreted to be caused by excitonic coupling. By comparison of experimental and computed (CNDO/S2 CIS) spectra detailed, structural models of the polymers were derived that consist of helix (H-aggregate behavior) and zigzag motifs (Jaggregate behavior). ■ INTRODUCTIONThe goal of this work is to synthesize polysquaraine dyes that are based on dicyanovinylene indolenine squaraine monomers and to study their optical and electrochemical properties. Squaraines (Scheme 1) are intensely colored dyes that are generated by 1,3-dicondensation reactions of nucleophilic compounds such as heterocycles or other electron-rich aromatics with squaric acid. This results in a donor− acceptor−donor structure with a strong and narrow cyaninelike absorption (ε > 10 5 M −1 cm −1 ) and fluorescence in the red to near-infrared (NIR) region. These unique absorption and fluorescence properties make squaraines suitable for a variety of applications in nonlinear optics, 1−7 data imaging, 8 organic photovoltaics, 9−17 or as fluorescence labels 18−21 and sensors for anions, 22 cations, 23−27 and neutral molecules. 28,29 There are several highly recommended reviews that give more-detailed insight into this remarkable class of dye. 30−33 The absorption maximum of squaraine dyes can be influenced by the nucleophilic component (e.g., anilines, pyrroles, indolenines and its heteroatom analogues), by replacing one oxygen of squaric carbonyl group by, e.g., sulfur 34,35 or methylene active moieties, such as dicyanomethylene 9,34,36 or barbituric acid, 34 and finally by adding electron-donating substituents to the nucleophilic (hetero)cycle component. We recently investigated the latter aspect, using triarylamine substituents attached to a series of indolenine squaraine dyes. 37 These triarylamine−squaraine conjugates display a bathochromic shift of the absorption maximum and versatile redox behavior. A totally different way to shift the absorption of squaraine dyes is to synthesize oligomers or polymers that then show band shifts and broadenings due to excitonic coupling of localized squaraine states. In this context, we recently prepared polymers based on indo...

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Section: Introductionmentioning

confidence: 94%

Section: ■ Introductionmentioning

confidence: 99%

Exciton Coupling Effects in Polymeric cis-Indolenine Squaraine Dyes

Völker¹,

Lambert²

2012

Chem. Mater.

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“…[38] Scheme 16 shows a selection of the difunctional monomers so far polymerized with squaric acid, 51, [40] 52, [41] 53, [42] 54, [43] 55, [44] 56. [45] In particular, Ajayaghosh performed a detailed study on the control of optical gap and electronic properties of the polysquaraines derived from monomer 55 and correlated structures.…”

Section: Polysquarainesmentioning

confidence: 99%

Squaraine Compounds: Tailored Design and Synthesis towards a Variety of Material Science Applications

2010

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The interest in squaraine compounds, a relatively old class of dyes, has been recently renewed due to their potential usefulness in a large number of technologically relevant fields such as two-photon absorbing materials, field-effect transistors, solar cells, NIR-emitting fluorescent probes and sensitizers for photodynamic therapy. Aim of the present review is to summarize the most convenient strategies for squaraines and polysquaraines syntheses and to discuss the design strategies enabling for the preparation of squaraines having properties relevant for a given material application. In particular, in the first section of the review we will describe the various synthetic approaches for the preparation of squaraine and polysquaraine derivatives. The second section will

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“…The reported band gap for this type III polysquaraine 9 was 0.79 eV, the lowest recorded for any pyrrole-derived polysquaraine. Some papers have reported band gaps but not actual electrical conductivities [30,31,41,50,51,54,62], although apart from 9, all reported band gaps exceed 1 eV. This in many respects is disappointing because pyrrole-derived polysquaraines approximate some of the theoretical chemicals models of Brocks and Tol and theoretically, the performance of pyrrole-derived squaraines should be better.…”

Section: Electrical Propertiesmentioning

confidence: 99%

“…One reason for doing this was the inclusion of pyrrolyl squaraines in the development of organic solar cells [30,31,41,48,51,53,54,57,63,69], or similarly for organic photovolatics [35,38,45,50,64,67]. It has also been possible that the some pyrrole-derived polysquaraines, such as that derived from pyrrole itself, can be used as black colour materials in toners and inks just because they are produced as black intractable powders [40].…”

Section: Optical Propertiesmentioning

confidence: 99%

Pyrrolyl Squaraines–Fifty Golden Years

Lynch

2015

Metals

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Pyrrolyl squaraines, both dyes and polymers, were first reported in 1965 and since then a fascinating body of work has been produced investigating the chemistry of these interesting molecules. A major aspect of these molecules that makes them so appealing to those researchers who have contributed to this field over the last 50 years is their chemical versatility. In this review, subjects, such as the synthetic history, an understanding of the molecular structure, an overview of the optical properties, a discussion of both the electrical conduction properties, and magnetic properties, plus use of the particles of pyrrolyl squaraines, are presented. Furthermore, previously published results are not just presented; they are in certain cases collated and used to both highlight and explain important aspects of pyrrolyl squaraine chemistry.

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Synthesis and characterization of novel low band-gap polymers containing squaraine units

Cited by 11 publications

References 13 publications

Exciton Coupling Effects in Polymeric cis-Indolenine Squaraine Dyes

Exciton Coupling Effects in Polymeric cis-Indolenine Squaraine Dyes

Squaraine Compounds: Tailored Design and Synthesis towards a Variety of Material Science Applications

Pyrrolyl Squaraines–Fifty Golden Years

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