Cross-Conjugated Chromophores:  Synthesis of <i>iso</i>-Polydiacetylenes with Donor/Acceptor Substitution

Ciulei, Sorin C.; Tykwinski, Rik R.

doi:10.1021/ol006491+

Cited by 28 publications

(18 citation statements)

References 19 publications

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“…Such push-pull functionalization is a wellestablished mode for dictating the electronic characteristics and molecular hyperpolarizabilities for various linearly conjugated molecules [5]. Our work [13], and that of others [7] [14] [15], has suggested that D/A-substitution can cause notable changes in the electronic-absorption behavior of cross-conjugated oligomers as well.…”

mentioning

confidence: 58%

Donor/Acceptor Effects on the Linear and Nonlinear Optical Properties of Geminal Diethynylethenes (g‐DEEs)

Zhao¹,

Zhou²,

Slepkov³

et al. 2007

Helvetica Chimica Acta

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A series of geminal diethynylethenes (g-DEEs) with electron-donating and/or electron-accepting (D/A) groups were synthesized via a Pd-catalyzed cross-coupling sequence. The UV/VIS spectra for donor -acceptor (D -A) functionalized g-DEEs 5, 8, and 11 show distinctive absorption trends attributable to intramolecular charge-transfer (ICT). The bond-length-alternation (BLA) index for the cross-conjugated enediyne framework varies slightly with different terminal substituents as determined by density-functional theory (DFT) calculations and single-crystal X-ray analysis. Ultrafast third-order optical nonlinearities for the g-DEEs were measured by the differential optical Kerr effect (DOKE) technique and show that terminal donor -acceptor substitution of g-DEEs enhances molecular second hyperpolarizabilities (g) in comparison to donor or acceptor g-DEEs. A small increase in the twophoton-absorption cross-section (s (2) ) is observed in the series 9 -11 as a result of increased functionalization. The effects of donor/acceptor substitution on electron delocalization along the cross-conjugated enediyne structure are evaluated on the basis of natural-bond-orbital (NBO) analysis. Solid-state structures of the four derivatives 3b, 4b, 7 and 8 were characterized by single-crystal X-ray structural analysis and show an asymmetric unit cell for one derivative, D -A g-DEE 8.1. Introduction. -Conjugated molecules with highly delocalized and polarizable pelectron systems are prospects for third-order nonlinear optical (NLO) materials, and could form the basis for achieving ultrafast all-optical-based computing and telecommunications technology [1] [2]. To find ideal and applicable organic NLO materials, a large number of organic chromophores have been extensively explored, with many efforts focused on linearly conjugated aromatic and/or nonaromatic pconjugated systems [2 -5]. In assessing the suitability of an organic material for NLO purposes, its efficiency/transparency trade-off at a specific wavelength is an important factor to be considered, and maintaining transparency in the visible region of the spectrum is a significant challenge [6]. Many linearly p-conjugated chromophores tend to perform poorly in this respect, and the pursuit of alternative molecular designs has become more and more appealing and important. In particular, the use of cross-

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mentioning

confidence: 58%

Donor/Acceptor Effects on the Linear and Nonlinear Optical Properties of Geminal Diethynylethenes (g‐DEEs)

Zhao¹,

Zhou²,

Slepkov³

et al. 2007

Helvetica Chimica Acta

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“…69 Evidence for intramolecular charge-transfer via cross conjugation came from UV-vis spectroscopy, which showed that D-A monomer 74a has a lower energy absorption tail that extends out beyond 450 nm, whereas 72a and 73a were transparent beyond about 425 nm. It was concluded, however, that charge-transfer mediated by the enyne framework was not present in the D-A dimer (74b) and trimer (74c).…”

Section: Iso-polydiacetylenesmentioning

confidence: 99%

Oligomeric and Polymeric Systems with a Cross-conjugated π-Framework

2006

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“…Multiple conduction pathways in different dimensions are accessible by using cross-conjugated compounds 20–22,29,30. Electron-donor and -acceptor moieties are frequently incorporated into cross-conjugated structures to improve the dimensionality of electronic communication 4,5,10,22,27,36–40. Judicial placement of the donor and acceptor groups allows spatial separation of the HOMO and LUMO, as revealed by quantum-mechanical calculations.…”

Section: Introductionmentioning

confidence: 99%

Controlling the Conformational Changes in Donor–Acceptor [4]‐Dendralenes through Intramolecular Charge‐Transfer Processes

Kanibolotsky

Forgie

McEntee

et al. 2009

Chemistry A European J

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The synthesis of two [4]-dendralene compounds incorporating thiophene-(p-nitrophenyl) donor–acceptor units is presented. The dendralenes adopt two different conformers in solution and solid state and the transformation between the structures can be controlled by light and heat. The electron-donating components of the dendralenes are represented by bromothienyl (in 13) and ethylenedioxythiophene(EDOT)-thienyl (in 15) end-groups. The most facile transformation involves the isomerisation of donor–acceptor conjugated systems (a conformers) into structures in which only the thiophenes are conjugated (b conformers), and this process is driven by ambient light. The structures of the two conformers of compound 13 are confirmed by single-crystal X-ray diffraction studies and the structural changes in both compounds have been monitored by 1H NMR spectroscopy and absorption studies. The transformations were found to be first-order processes with rate constants of k = 0.0027 s−1 and k = 0.00022 s−1 for 13 and 15, respectively. Density functional theory calculations at the B3LYP/6-31G∗ level give credence to the proposed mechanism for the a→b conversion, which involves photoinduced intramolecular charge transfer (ICT) as the key step. The EDOT derivative (15) can be polymerised by electrochemical oxidation and a combination of cyclic voltammetry and UV/Vis spectroelectrochemical experiments indicate that the a conformer can be trapped and stabilised in the solid state.

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Cross-Conjugated Chromophores: Synthesis of iso-Polydiacetylenes with Donor/Acceptor Substitution

Cited by 28 publications

References 19 publications

Donor/Acceptor Effects on the Linear and Nonlinear Optical Properties of Geminal Diethynylethenes (g‐DEEs)

Donor/Acceptor Effects on the Linear and Nonlinear Optical Properties of Geminal Diethynylethenes (g‐DEEs)

Oligomeric and Polymeric Systems with a Cross-conjugated π-Framework

Controlling the Conformational Changes in Donor–Acceptor [4]‐Dendralenes through Intramolecular Charge‐Transfer Processes

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