Polytriacetylenes: Conjugated polymers with a novel all‐carbon backbone

Schreiber, Martin; Anthony, John E.; Diederich, François; Spahr, Michael E.; Nesper, Reinhard; Hubrich, Michael; Bommeli, F.; Degiorgi, L.; Wächter, P.; Kaatz, Phil; Bosshard, Christian; Günter, Peter; Colussi, Martin; Suter, Ulrich W.; Boudon, Corinne; Gisselbrecht, Jean‐Paul; Gross, Maurice

doi:10.1002/adma.19940061017

Cited by 74 publications

(65 citation statements)

References 25 publications

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“…4 ) , and from the intercept, the optical gap for a long-chain PTA with tetraethynylethene repeating units was predicted as 540 nm (2.25 eV). This predicted value is in very good agreement with the experimental value of 2.1 eV determined later for such longer-chain polymers [8], vdhdifying once more the concept of studying soluble oligomers to predict and understand the properties of often insoluble polymers. The electrochemical properties of the PTA rods were studied by polarography and cyclic voltammetry in THF (mercury working electrode; electrolyte: 0.…”

Section: Fig 1 Lbrcvdy ~Onjugatedpolyenrs Und the Isomeric Cross-csupporting

confidence: 76%

“…-Following the first preparation of the parent tetraethynylethene 1 in 1991 111, synthetic routes to derivatives with any desired substitution and protection pattern were worked out [2] [3]. This versatile 'molecular construction kit' provided access to acetylenic C-rich nanostructure [4] precursors to all-C-networks [ 51 [6] and to linearly conjugated polymers with the novel poly(triacety1ene) (PTA; poly(hex-1-ene-33-diyne)) backbone [7] [8]. In this paper, we describe acyclic molecular C-scaffolding and linear polyenes dendralenes poly(triacety1ene) expanded dendralene…”

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confidence: 99%

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Acyclic Tetraethynylethene Molecular Scaffolding: Multinanometer‐sized linearly conjugated rods with the poly(triacetylene) backbone and cross‐conjugated expanded dendralenes

Boldi¹,

Anthony²,

Gramlich

et al. 1995

Helvetica Chimica Acta

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Derivatives of fully cross-conjugated tetraethynylethene (3,4-diethynylhex-3-ene-l,5-diyne) 1 are versatile precursors to multinanometer-sized molecular rods with all-C-backbones. Oxidative polymerization (CuCI, N,N,N',h" -tetramethylethylenediamine (TMEDA), 0 2 ) of the trans-bis-deprotected trans-bis(triisopropylsily1)-protected tetraethynylethene 2 yielded, after end-capping with phenylacetylene, the remarkably stable, soluble oligomers 3-7 with a persilylethynylated poly(triacety1ene) (PTA) backbone [-(C=C-CR=CR-C=C),-] and a length of 19.4 (3), 26.8 (4), 34.3 (5), 41.8 (6), and 49.2 (7) 8, (Scheme I ) . These compounds underwent facile one-electron reductions with the number of reversible reduction steps being equal to the number of tetraethynylethene moieties in each molecular rod. Oxidative Eglinton-Claw homo-coupling of tetraethynylethenes 8-10 with a single free ethynyl group provided the fully silyl-protected 3,4,9,1O-tetraethynyl-substituted dodeca-3,9-diene-1,5,7,1 I-tetraynes 11-13 (Scheme 2) and, after alkyne deprotection, the novel hydrocarbon 14, a C20H6 isomer, and its partially silyl-protected derivative 15. Oxidative hetero-coupling between two different tetraethynylethene derivatives, one with a single and the other with two free terminal ethynyl groups, yielded the extended chromophores 1 6 2 1 composed of 3 or 4 tetraethynylethene moieties (Scheme 3 ) . The linearly conjugated oligomers 16 and 17 with the PTA backbone are isomeric to 19 and 20, respectively, which are members of the cross-conjugated expanded dendralenes, ie., dendralenes with butadiynediyl fragments inserted between each pair of double bonds [-(C=C-C(=CR,)-C=C),-l.The electronic absorption spectra of these compounds were compared and analyzed in terms of the competition between linear and cross-conjugation in determining the extent of rc-electron delocalization. Although steric factors on 71 -electron conjugation remain to be clarified, this analysis strongly suggests that cross-conjugation is not an efficient mechanism for n-electron delocalization. All extended acetylenic-olefinic chromophores considered in this study exhibited remarkably high stability and did not decompose when exposed to laboratory air and light for months. In agreement with this observation, electrochemical studies demonstrated that the compounds are difficult to oxidize with the oxidation potentials in THF (0.lM (Bu,N)PF,) being higher than 1 .O V (vs. the ferrocene/ferrocenium couple).

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Section: Fig 1 Lbrcvdy ~Onjugatedpolyenrs Und the Isomeric Cross-csupporting

confidence: 76%

mentioning

confidence: 99%

Acyclic Tetraethynylethene Molecular Scaffolding: Multinanometer‐sized linearly conjugated rods with the poly(triacetylene) backbone and cross‐conjugated expanded dendralenes

Boldi¹,

Anthony²,

Gramlich

et al. 1995

Helvetica Chimica Acta

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“…These poly(triacetylene) (PTA) oligomers [12] displayed high stability and solubility, as well as interesting third-order NLO properties. For the preparation of conjugated molecular rods with further enhanced properties, we became interested in hybrid systems in which Zn II porphyrin moieties are interlinked by such DEE units.…”

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confidence: 99%

Porphyrin-[(E)-1,2-Diethynylethene] Scaffolding: Synthesis and Optical and Electrochemical Properties of Multinanometer-Sized Porphyrin Arrays

Wytko

Berl

McLaughlin

et al. 1998

HCA

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“…These oligomers served as invaluable model compounds for high-molecular-weight poly(triacetylene) ( PTA ) polymers [9] [10] and allowed the establishment of comprehensive structure-property relationships for redox as well as linear and nonlinear optical properties. PTA Polymers [9], their monomeric components, such as arylated DEEs and tetraethynylethenes ( 3,4-diethynylhex-3-ene-1,5-diynes, TEEs) [11], and linear [11] and cyclic [12] oligomers made of arylated DEEs and TEEs feature attractive nonlinear optical ( NLO ) properties combined with good solution processability and thermal stabilities.…”

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confidence: 99%

Modulation ofπ-Electron Conjugation in Oligo(triacetylene) Chromophores by Incorporation of a Central Spacer

Martin

Wytko

Diederich

et al. 1999

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A comprehensive series of trimeric hybrid oligomers 4 – 14 (Fig. 2) was prepared by insertion of different hetero‐spacers between two (E)‐hex‐3‐ene‐1,5‐diyne (=(E)‐1,2‐diethynylethene, DEE) moieties, and the optical and electrochemical properties of the resulting π‐conjugated materials compared to those of the DEE dimer 2 and trimer 3, which formally contains a DEE moiety as homo‐spacer. The hetero‐spacers varied from benzenoid (phenylene, naphthalene, biphenylene, anthracene), to π‐electron‐deficient (pyrazine, pyridine) and π‐electron‐rich (thiophene, furan) aromatic rings, and to an organometallic trans‐Pt(PEt3)2 fragment. The hybrid oligomers were synthesized following a general strategy which relied on the Sonogashira cross‐coupling between mono‐deprotected DEE 15 and the appropriately bis‐functionalized spacer (Scheme and Table 1). UV/VIS Studies revealed that the majority of the hetero‐spacers were less effective than the homo‐spacer DEE in facilitating π‐electron delocalization along the linearly conjugated oligomeric backbone (Table 2 and Fig. 3). With increasing degree of benzenoid aromaticity in the hetero‐spacer, the electronic communication between the terminal DEE moieties in the hybrid oligomers was reduced. As a remarkable exception, a large bathochromic shift of the longest‐wavelength absorption maximum, which is indicative of enhanced π‐electron delocalization, was obtained upon introducing an anthracene‐9,10‐diyl moiety as hetero‐spacer into oligomer 7 (Figs. 3 and 6). Electrochemical investigations by cyclic and steady‐state voltammetry confirmed the limited extent of π‐electron delocalization in the majority of the hybrid oligomers (Table 3). The fluorescence properties of many of the DEE hybrid materials were dramatically enhanced upon incorporation of the hetero‐spacers (Table 2). The heterocyclic derivatives 10 – 12, containing pyridine, pyrazine, or thiophene spacers, respectively, displayed a strong fluorescence emission, which is present to a significant extent neither in DEE homo‐oligomers nor in the individual heteroaromatic spacer components, demonstrating the value of combining different repeat units to modulate oligomeric and polymeric properties. The pyridine derivative 10 provided an interesting example of a molecular system, in which both the electronic absorption (Fig. 4) and emission characteristics (Table 2) can be reversibly switched as a function of pH (Fig. 5).

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Polytriacetylenes: Conjugated polymers with a novel all‐carbon backbone

Abstract: CuCI, TMEDA, 3,5-bis-(fert-butyi)phenylacetylene (0.01 eq.), 1 ,2-dichlorobenzene, molecular sieve 4,&, 02.65 'C, 3 h, 90 %

Cited by 74 publications

References 25 publications

Acyclic Tetraethynylethene Molecular Scaffolding: Multinanometer‐sized linearly conjugated rods with the poly(triacetylene) backbone and cross‐conjugated expanded dendralenes

Acyclic Tetraethynylethene Molecular Scaffolding: Multinanometer‐sized linearly conjugated rods with the poly(triacetylene) backbone and cross‐conjugated expanded dendralenes

Porphyrin-[(E)-1,2-Diethynylethene] Scaffolding: Synthesis and Optical and Electrochemical Properties of Multinanometer-Sized Porphyrin Arrays

Modulation ofπ-Electron Conjugation in Oligo(triacetylene) Chromophores by Incorporation of a Central Spacer

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