C.A. Christensen
New strategies and building blocks for functionalised 9,10-bis(1,3-dithiol-2-ylidene)-9,10-dihydroanthracene derivatives, including pyrrolo-annelated derivatives and pi-extended systems with intramolecular charge-transfer
Christensen, C.A.; Bryce, M.R.; Batsanov, A.S.; Becher, J.
Abstract
A range of new functionalised 9,10-bis(1,3-dithiol-2-ylidene)-9,10-dihydroanihracene (TTFAQ) derivatives have been synthesised from the key di(halomethyl) building blocks, 10-[4,5-bis(bromomethyl)-1,3-dithiol-2-ylidene]7 anthracene-9(10H)-one 10, 10-[4,5-bis(chloromethyl)-1,3-dithiol-2-ylidene]anthracene-9(10H)-one 11 and 9-[4,5-bis(chloromethyl)-1,3-dithiol-2-ylidene]-10-[4,5-bis(hexylsulfany l)-1,3-dithiol-2-ylidene]-9,10-dihydro-anthracene 18. A Diels-Alder strategy comprising trapping of the transient exocyclic diene 19, which is derived from 18, with 1,4-naphthoquinone leads to the aromatised TTFAQ anthraquinone system 21. Horner-Wadsworth-Emmons olefination of 21 with the anion generated from reagent 22 gave the fused bis(TTFAQ) structure 23. Pyrrolo-annelated derivatives 30-34 have been obtained in a sequence of reactions from compound 10. Monoformylation of the pyrrole ring of 32 and 33 under Vilsmeier conditions gave 35 and 36 which upon reaction with 2,4,5,7-tetranitrofluorene gave the donor-pi-acceptor diads 38 and 39. Cyclic voltammetry (CV) in solution for all the TTFAQ derivatives shows the typical quasi-reversible two-electron oxidation wave of the TTFAQ core at potentials which vary slightly depending on the substituents. For example, the value of E-ox is raised by the electron withdrawing anthraquinone and tetranitrofluorene units of 21 and 38, respectively The CV of the conjugated TTFAQ dimer 23 showed two, two-electron oxidation waves corresponding to the sequential formation of 23(2+) and 23(4+) (DeltaE(ox) = 130 mV) providing evidence for a significant intramolecular electronic interaction, i.e. the dication 23(2+) acts as a conjugated donor-pi-acceptor diad, thereby raising the oxidation potential of its partner TTFAQ unit. Spectroelectrochemical studies on 23 support this explanation. A strong intramolecular charge transfer band at lambda(max) 538 nm is seen in the UV-Vis spectra of the TTFAQ-pi-tetranitrofluorene diads 38 and 39. The X-ray crystal structures are reported for compounds 30, 33 and 34. The pyrrolo-TTFAQ moiety adopts a saddle-shape with the central ring of the dihydroanthracene moiety folded along the C(9)...C(10) vector in each case. Significant intermolecular interactions are observed in the structures.
Journal Article Type | Article |
---|---|
Publication Date | 2003-02 |
Journal | Organic and Biomolecular Chemistry |
Print ISSN | 1477-0520 |
Publisher | Royal Society of Chemistry |
Peer Reviewed | Peer Reviewed |
Volume | 1 |
Issue | 3 |
Pages | 511-522 |
Public URL | https://durham-repository.worktribe.com/output/1595274 |
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