Aryleneethynylenes

By using a cocatalyst of Pd-Cu, aryl-alkenyl halides couple efficiently widi alkynes to generate die disubstituted alkynes (Scheme 9.6).8 This coupling reaction has been applied to die synthesis of polyphenyleneethynylenes by Yamamoto et al. in 1984 (Scheme 9.7).9a Due to the ready availability of diacetylenes and the mild coupling condition, this strategy has been widely used for die preparation of many poly(aryleneethynylene)s.9... 

Bunz UHF (2000) Poly(aryleneethynylene)s syntheses, properties, structures, and applications. Chem Rev 2000 1605-1644... 

Bangcuyo CG, Ellsworth JM, Evans U, Myrick ML, Bunz UF1F (2003) Quinoxaline-based poly(aryleneethynylene)s. Macromolecules 36 546-548... 

Giesa R (1996) Rev Macromol Chem Phys C36 631-670 Synthesis and properties of conjngated poly(aryleneethynylene)s... 

Abstract This review describes recent results in the field of poly(aryleneethynylene)s (PAEs) that contain metal ions in the polymer backbone, or in the polymer side chain. This work is focused primarily on polymers possessing ligands of metal complexes as part of the aryle-neethynylene chain. PAEs with porphyrinylene in the backbone have also been addressed. Synthetic routes toward the polymers, as well as their photochemical, photophysical, and electrochemical properties, are presented. Monodisperse oligo(phenyleneethynylene)s with terminal metal complexes or with a ferrocene and thiol at each end are mentioned. 

In 1997, Yamamoto et al. reported aryleneethynylene polymers with ferrocene (Fc) in the repeating unit [71]. Several aromatic diynes were coupled with 1,1 -diiodoferrocene 61 (Scheme 10, Table 3). 

Co-free PAE). In PAE-CoCpl, the fluorescence quantum yield is only 18% of that observed for Co-free PAE, even though the quencher substitutes less than 0.1% of the aryleneethynylene units. The fluorescence in solution disappeared in PAE-CoCp4, where every fifth unit is a cyclobutadiene complex. The mechanism by which this quenching occurs is via the cobalt-centered MLCT states [82,83], conferred onto the polymer by the presence of cyclobutadiene complexes. Even in the solid state the polymers PAE-CoCpl-2 are nonemissive. It was therefore shown that incorporation of CpCo-stabilized cyclobutadiene complexes into PPEs even in small amounts leads to an efficient quenching of fluorescence in solution and in the solid state. Quenching occurs by inter- and intramolecular energy transfer [84]. 

Keywords Poly(aryleneethynylene) Heteroaromatic ring Palladium-catalyzed coupling Optical properties Chemical reactivity... 

The Pd-catalyzed C-C coupling (Sonogashira coupling) was applied to polymer synthesis about 20 years ago [23-25], and has especially been developed for the synthesis of n-conjugated poly(aryleneethynylene)s (PAEs) (for reviews, see refs. [16,26-33]). Recently other synthetic routes for PAEs were also developed, e.g., the alkyne metathesis method [28, 34] and the coupling reaction of =C-MR3 with R X (M=Si [35, 36] or Sn [37, 38]). In this review, we are concerned with the synthesis and chemical properties of PAEs with heteroaromatic rings. 

Williams, V. and T. M. Swager. Iptycene-containing poly(aryleneethynylene)s. Macromolecules 33, 4069-4073 (2000). 

Optical Properties and Photophysics of Platinum-Containing Poly(aryleneethynylene)s... 

This contribution describes the synthesis and properties of organic alkyne-bridged materials that have been made by alkyne metathesis or by Acyclic Diyne Metathesis (AD I MET). This review covers mostly poly(aryleneethynylene)s made at the author s laboratory in South Carolina. A comprehensive review covering poly(aryleneethynylene)s listing important contributions in adjacent areas has appeared [1, 2]. This chapter discusses the synthesis and properties of dialkyl-poly(paraphenyleneethynylene)s (dialkyl-PPEs) in relation to the concept of ADIMET with simple catalyst systems. 

The first reported thermotropic and lyotropic liquid-crystalline poly(aryleneethynylene)s were not parent PPEs, but organometallic derivatives 65 made by the Pd-catalyzed condensation of Vollhardt s diethynyl 64 with diiodobenzenes 46 [45]. The polymers were isolated in good to excellent yields as amorphous tan or red powders with moderate Pn values of... 

Fig. 4. Supramolecular arrangements of organometallic (65) and organic poly(aryleneethynylene)s (12) in the solid state.

Rigid conjugated poly (aryleneethynylene)s have been shown to interact with SWNTs through tt-tt stacking. 

Figure 36 A molecular model of ji-ji complex of a rigid conjugated poly(aryleneethynylene) with SWNT (6,6) and H NMR spectra the complex with HiPco SWNT. (Reprinted with permission from Ref 242. 2002 American Chemical Society)...

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