Enhancement of Push–Pull Properties of Pentafulvene and Pentafulvalene Derivatives by Protonation at Carbon

Haberland, Sophie; Finke, Aaron D.; Kerisit, Nicolas; Katan, Claudine; Trolez, Yann; Gaweł, Przemysław; Leito, Ivo; Lõkov, Märt; Järviste, Robert; Kaupmees, Karl; Trapp, Nils; Boudon, Corinne; Himmel, Daniel; Diederich, François

doi:10.1002/ejoc.201800039

Cited by 9 publications

(14 citation statements)

References 47 publications

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“…The newly obtained values are generally in good agreement with those published earlier , , . For 78 % of bases the differences are less than 0.03 p K a units and for 98 % of bases less than 0.1 p K a units.…”

Section: Resultssupporting

confidence: 91%

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On the Basicity of Organic Bases in Different Media

et al. 2019

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The basicities of simple organic bases – aliphatic and aromatic amines, amidines, phosphazenes, as well as saturated and unsaturated nitrogen heterocycles – are examined in acetonitrile, dimethyl sulfoxide, tetrahydrofuran, water and the gas phase. The basicities (pKaH values) of conjugate acids of a large variety of bases in these media are presented and discussed. Equations employing easily usable structural descriptors have been derived for approximately converting basicities from acetonitrile to other solvents. Recommendations are given on their practical use and a number of pKaH values that are experimentally unavailable are estimated from these relationships. An important part of the minireview is a large compilation of pKaH and GB values of the compounds in solvents and the gas phase, respectively, as well as the revised basicity scale in acetonitrile, now containing more than 270 pKaH values.

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Section: Resultssupporting

confidence: 91%

“…The revised basicity scale (Table ) is composed of previously published data, , and unpublished results for 9‐chloroacridine and 2‐aminoacridine (experimental conditions as in ref …”

Section: Methodsmentioning

confidence: 99%

On the Basicity of Organic Bases in Different Media

et al. 2019

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“…The pentafulvalene-expanded cumulene shows slightly weaker bond-length alternation than the other systems but still considerably stronger than the unsubstituted cumulene. These values are in good agreement with crystallographic data of similar systems. ,,,, …”

Section: Increasing Reverse Bond-length Alternation In Cumulenessupporting

confidence: 89%

“…These values are in good agreement with crystallographic data of similar systems. 109,110,113,120,123 By increasing the reverse bond-length alternation, the reverse conductance decay trend is increased. In Figure 7, the transmission of the penteheptafulvalene-and pentafulvalene-expanded cumulenes are calculated with DFT as in the previous section.…”

Section: ■ Dft Transmissionmentioning

confidence: 99%

Reverse Bond-Length Alternation in Cumulenes: Candidates for Increasing Electronic Transmission with Length

et al. 2018

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Single-molecule conductance generally decays exponentially with the length of the molecule when the transport mechanism is a coherent tunneling process. However, it was recently found that this length dependence can be reversed in linear conjugated molecules if the bond-length alternation is reversed. In this work we show that even-carbon cumulenes show this behavior as the bond lengths are reversed for the dominant π-system compared to the equivalent polyenes and polyynes. We explore the electronic origins of the reversed bond-length alternation in cumulenes and its relation to the length dependence of the electronic transmission. Through density functional theory and nonequilibrium Greens function calculations we predict that cumulenic wires have reverse decay of transmission with length; that is, the decay constant β is found to be negative. As a direct consequence of the reversed bondlength alternation, the electronic transmission increases with length as the highest occupied molecular orbital−lowest unoccupied molecular orbital gap rapidly narrows. On the basis of recent progress in cumulene synthesis, we discuss substituent strategies that may increase reverse bond-length alternation. Cumulenes stand out as promising candidates for a series of molecules that may show reverse decay of single-molecule conductance with increasing length.

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“…The chemistry of tria-, penta-, and heptafulvenes − and fulvalenes ,,− (Figure A), their synthetic preparation, and the study of their physical properties have been the subject of continuous interest throughout the past decades. These nonalternant hydrocarbons do not exhibit classic Hückel aromaticity but can form ionic species upon reduction (pentafulvenes) or oxidation (tria- and heptafulvenes) that experience substantial aromatic stabilization via cyclic delocalization.…”

Section: Introductionmentioning

confidence: 99%

Fulvenyl-Functionalized Polyisocyanides: Cross-Conjugated Electrochromic Polymers with Variable Optical and Electrochemical Properties

2018

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We describe the preparation of arylisocyanide monomers bearing conjugated fulvenyl groups derived from 9-benzylidene-9H-fluorene (Flu), 5-benzylidene-1,2,3,4-tetraphenylcyclopentadiene (TPCp), and 5-benzylidene-5H-dibenzo[a,d]cycloheptene (Dbs). The electrochemical and optical properties of the monomers and their precursors have been characterized and consistently showed the effect of the conjugation of the respective functional group (−NO2, −NH2, −NHCHO, and −NC) with the fulvenyl moiety. The isocyanides have been subsequently polymerized to the corresponding polyisocyanides (PICs), which exhibited number-average molecular weights of 124–136 kDa (PDI = 2.0–2.7), as determined by gel permeation chromatography in THF vs polystyrene standards. The thermal, optical, and electrochemical properties of the polymers have been studied in detail. Spectroelectrochemical analyses of polymers equipped with redox-active pentafulvene groups show reversible electrochromism, which allows to lower the optical gap from 2.38 to 1.20 eV (Flu) and from 2.27 to 1.55 eV (TPCp) via chemical or electrochemical reduction.

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Enhancement of Push–Pull Properties of Pentafulvene and Pentafulvalene Derivatives by Protonation at Carbon

Cited by 9 publications

References 47 publications

On the Basicity of Organic Bases in Different Media

On the Basicity of Organic Bases in Different Media

Reverse Bond-Length Alternation in Cumulenes: Candidates for Increasing Electronic Transmission with Length

Fulvenyl-Functionalized Polyisocyanides: Cross-Conjugated Electrochromic Polymers with Variable Optical and Electrochemical Properties

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