Conjugated Oligoenynes Based on the Diethynylethene Unit

Nielsen, Mogens Brøndsted; Diederich, François

doi:10.1021/cr9903353

Cited by 234 publications

(183 citation statements)

References 251 publications

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“…[1,2] These polymers with linearly p-conjugated scaffolds possess unique properties such as photoconductivity and third-order nonlinear optical properties. [3][4][5] Most of the conjugated polymers are, however, heterogeneous in conjugation length, which hampers systematic studies of their opto-A C H T U N G T R E N N U N G electronic properties. Moreover, the processing and characterization of these polymers can be difficult due to a low solubility in organic solvents.…”

Section: Introductionmentioning

confidence: 99%

“…Current research on the basic features of conjugated polymers is mostly devoted to the study of oligoenes, [10,11] oligothiophenes, [12][13][14][15][16][17][18] oligoarylenevinylenes, [19,20] oligoarylene-A C H T U N G T R E N N U N G ethynylene, [21] iso/cis-oligodiacetylenes (iso/cis-ODAs), [5,22,23] and oligotriacetylenes. [24][25][26][27][28][29][30] However, systematic investigations of the synthesis and optoelectronic properties of monoA C H T U N G T R E N N U N G disperse all-trans-oligodiacetylenes (or trans-oligo-A C H T U N G T R E N N U N G enynes) still remain very scarce.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and Optical Properties of all‐trans‐Oligodiacetylenes

Pilzak

Lagen

Hendrikx

et al. 2008

Chemistry A European J

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A new series of pure and highly soluble oligodiacetylenes (ODAs) was synthesized in high yield and on a multi-milligram scale by a sequence of Sonogashira reactions with a strongly reduced level of homocoupling. The lambda max and epsilon max of these ODAs show an increase with both chain elongation and solvent polarity. A plot of lambda max absorption versus 1/CL (CL=conjugation length) was shown to be linear. The lambda max converges to 435 nm for the longest members of the series at micromolar concentration. This reveals that the longest wavelength absorption observed for PDA chains (lambda max up to 700 nm) is due to aggregation effects. The fluorescence quantum yield increased from monomer to trimer and decreased for longer ODAs. A similar trend is found for the lifetime of fluorescence with a maximum of 600 ps for the trimer. The observed linearity of the rotational correlation time with the oligomer length implies that the ODA chains in solution lack significant geometrical changes. This implies that the ODAs in solution are fully stretched molecular rods of up to 4 nm in length.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis and Optical Properties of all‐trans‐Oligodiacetylenes

Pilzak

Lagen

Hendrikx

et al. 2008

Chemistry A European J

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“…The 31 P NMR spectrum of 7 features a pair of doublets at d = 348.5 and 356.3 ppm due to the presence of chemically different P=C units. Considering the P···P distance of 8.7 (as deduced from 3 b and 6), the coupling constant of 7 JA C H T U N G T R E N N U N G (P,P) = 25.8 Hz is stunningly large, which indicates that the two P centers in 7 are part of one common p system that provides a large degree of communication. If the P centers were not part of the same p system, a much lower coupling constant would be expected, for example, that between two tertiary s 3 l 3 phosphanes that are bridged by a butadiyne linker (…”

Section: Resultsmentioning

confidence: 99%

“…Mixing the phosphaalkene-based fragment orbitals with those of the appended acetylene framework leads to smaller HOMO-LUMO gaps in the entire p conjugates than in the allcarbon-based reference compounds. Furthermore, communication between the two P=C units is effectively mediated by the central butadiyne as evidenced by the unexpectedly large coupling constant of 7 JA C H T U N G T R E N N U N G (P,P) = 25.8 Hz in the 31 P NMR spectrum of 7.…”

Section: Resultsmentioning

confidence: 99%

Acetylene‐Expanded Dendralene Segments with Exotopic Phosphaalkene Units

Geng

Ott

2011

Chemistry A European J

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Bis-TMS protected C,C-diacetylenic phosphaalkene (A(2)PA) 1 (Mes*P=C(C≡CTMS)(2); Mes* = 2,4,6-tBu(3)Ph) has been used as a building block for the construction of butadiyne-expanded dendralene fragments in which phosphaalkenes feature as exotopic double bonds. Treatment of 1 with CuCl gives rise to a Cu(I) acetylide that is selectively formed at the acetylene trans to the Mes* group. The cis-TMS-acetylene engages in similar chemistry, albeit at higher temperatures and longer reaction times. The differentiation between the two acetylene termini of 1 allows for the controlled synthesis of the title compounds by a variety of different Cu- and Pd-catalyzed oxidative acetylene homo- and heterocoupling protocols. Crystallographic characterization of A(2)PA 1 and dimeric Mes*P=C(C≡CR(1))C(4)(R(2) C≡C)C=PMes* (3b, R(1) = R(2) = Ph; 6, R(1) = R(2) = TMS), and 10 (R(1) = R(2) = C≡CPh) verifies that the stereochemistry across the P=C bond is conserved during the coupling reactions, whereas spectroscopic evidence reveals cis/trans isomerization in an iodo-substituted A(2)PA intermediate 4 (Mes*P=C(C≡CTMS)(C≡CI). UV/Vis spectroscopic and electrochemical studies reveal that efficient π conjugation operates through the entire acetylenic phosphaalkene framework, even in the cross-conjugated dimeric structures. The P centers contribute considerably to the frontier molecular orbitals of the compounds, thereby leading to smaller HOMO-LUMO gaps than in all-carbon-based congeners. Phenyl- and/or ethynylphenyl substituents at the A(2)PA framework influence the HOMO and LUMO to a varying degree depending on their relationship to the Mes* group, thus enabling a fine-tuning of the frontier molecular orbitals of the compounds.

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“…1) [10][11][12][13][14] served as starting materials for the construction of well-defined, carbon-rich molecular architectures and advanced functional materials [15][16][17]. Monodisperse π-conjugated poly(triacetylene) (PTA) oligomers 1a-h ( Fig.…”

Section: Acetylenic Scaffolding-a Molecular Construction Kitmentioning

confidence: 99%

Conjugation and optoelectronic properties of acetylenic scaffolds and charge-transfer chromophores

Kivala

Diederich

2008

Pure and Applied Chemistry

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Our group started a research program in acetylene chemistry in 1987; since then, an intense research effort led to a fascinating journey into acetylenic scaffolding, aimed at exploring conjugative and optoelectronic properties of acetylenic chromophores. This journey included the generation of a unique molecular construction kit for acetylenic scaffolding, consisting of (E)-1,2-diethynylethenes [DEEs, (E)-hex-3-ene-1,5-diynes], tetraethynylethenes (TEEs, 3,4-diethynylhex-3-ene-1,5-diynes), chiral 1,3-diethynylallenes (DEAs, hepta-3,4-diene-1,6-diynes), 1,4-di and 1,1,4,4-tetraethynylbutatrienes, chiral trialkynylmethanes, and 1,1,2,2-tetraethynylethanes. These building modules were subsequently applied to the synthesis of carbon-rich architectures extending into one, two, and three dimensions. They include multinanometer-long monodisperse oligomers as models for infinite acetylenic polymers, molecular switches, perethynylated dehydroannulenes, expanded radialenes, and radiaannulenes, and an octamethoxy-substituted expanded cubane with a central C 56 core. Donor-substituted cyanoethynylethenes (CEEs) and 1,1,4,4-tetracyanobuta-1,3-dienes (TCBDs) were introduced as new push-pull chromophores featuring intense intramolecular charge-transfer (CT) interactions. Dendritic multivalent CT chromophores were constructed using atom-economic, "click"-like reactions, and these systems were shown to behave as "molecular batteries", featuring exceptional electron uptake and storage capacity. The research finally led to the development of an unprecedented cascade reaction for the preparation of dendritic and oligomeric donor-acceptor (D-A) molecules. New [AB]-type oligomers become accessible in domino reactions involving repetitive sequences of [2+2] cycloadditions of tetracyanoethylene (TCNE) and tetrathiafulvalene (TTF) to polyynes, followed by retro-electrocyclizations.

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Conjugated Oligoenynes Based on the Diethynylethene Unit

Cited by 234 publications

References 251 publications

Synthesis and Optical Properties of all‐trans‐Oligodiacetylenes

Synthesis and Optical Properties of all‐trans‐Oligodiacetylenes

Acetylene‐Expanded Dendralene Segments with Exotopic Phosphaalkene Units

Conjugation and optoelectronic properties of acetylenic scaffolds and charge-transfer chromophores

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