302906-76-9

Upstream product

• 68-12-2 N,N-dimethyl-formamide 
• 302906-75-8 (E)-4,5,4',5'-Tetrahydro-[6,6']bi[cyclopenta[b]thiophenylidene] 

Downstream Products

• 302906-83-8 (E)-2-formyl-2'-[(E)-(4-N,N-dimethylaminobenzylidene)methyl]-6,6'-bis(4,5-dihydro-6H-cyclopenta[b]thienylidene) 
• 302906-84-9 (E)-2-formyl-2'-2-[(E)-(4-N,N-dihexylaminobenzylidene)methyl]-6,6'-bis(4,5-dihydro-6H-cyclopenta[b]thienylidene) 
• 302906-81-6 Dihexyl-{4-[(E)-(E)-2-(4,5,4',5'-tetrahydro-[6,6']bi[cyclopenta[b]thiophenylidene]-2-yl)-vinyl]-phenyl}-amine 
• 302906-79-2 (E)-2-[(E)-(4-N,N-dimethylaminobenzylidene)methyl]-6,6'-bis(4,5-dihydro-6H-cyclopenta[b]thienylidene) 

Relevant academic research and scientific papers

Fine tuning of the electronic properties of linear π-conjugated oligomers by covalent bridging

A series of oligothienylenevinylenes, π-conjugated oligomers rigidified by ethylene bridges attached at different sites of the conjugated backbone, have been constructed by multistep synthetic methodologies. Electronic absorption spectra show that the rigidification of the conjugated system produces a bathochromic shift of the absorption maximum and a narrowing of the HOMO-LUMO energy gap, as compared to the spectra of an open-chain reference compound. The cyclic voltammograms of all oligomers show that these compounds can be reversibly oxidized into their cation radicals and dications and that rigidification produces a large negative shift of the first oxidation potential, which is indicative of a considerable increase of the HOMO level. Electrochemical data confirm that covalent bridging strongly affects the HOMO and LUMO levels and these data demonstrate that the sites of fixation of the bridges on the π-conjugated backbone exert a determining effect on the relative stability of the cation radical and dication. Examination of these various results in the light of theoretical calculations shows that in addition to a local control of bond length alternation, and hence of the HOMO-LUMO gap, the fixation of covalent bridges at selected positions of the π-conjugated system limits the deformation of the π-conjugated structure upon oxidation to the charged states.

Design and synthesis of push-pull chromophores for second-order nonlinear optics derived from rigidified thiophene-based π-conjugating spacers

Two series of push-pull chromophores built around thiophene-based π-conjugating spacers rigidified either by covalent bonds or by noncovalent intramolecular interactions have been synthesized and characterized by UV-vis spectroscopy, electric field induced second harmonic generation (EFISH) and differential scanning calorimetry. Comparison of the linear and second-order nonlinear optical properties of chromophores based on a covalently bridged dithienylethylene (DTE) spacer with those of their analogues based on open chain DTE shows that the rigidification of the spacer produces a considerable bathochromic shift of the absorption maximum together with a dramatic enhancement of the molecular quadratic hyperpolarizability (μΒ) which reaches values among the highest reported so far. A second series of NLO-phores has been derived from a 2,2′-bi(3,4-ethylenedioxythiophene) (BEDOT) π-conjugating spacer. As indicated by X-ray and UV-vis data, rigidification of the spacer originates in that case, from noncovalent intramolecular interactions between sulfur and oxygen atoms. Again, comparison with the parent compounds based on an unsubstituted bithiophene spacer reveals a marked red shift of the absorption maximum and a large enhancement of μΒ. In an attempt to distinguish the contribution of the electronic and geometrical effects of the ethylenedioxy group, a third series of NLO-phores based on 3,4-ethylenedioxythiophene (EDOT) and 3,4-dihexyloxythiophene spacers has been synthesized. Comparison with compounds based on unsubstituted thiophene shows that, despite a red shift ofλmax, introduction of alkoxy groups leads to a decrease of μΒ. Theoretical calculations indicate that this effect results from a decrease of the dipole moment (μ) caused by the auxiliary electron-donor alkoxy groups on the thiophene ring. In contrast, replacement of BT by BEDOT produces an increase of μ, which associated with the noncovalent rigidification of the BT system accounts for the observed enhancement of μΒ.

Huge enhancement of the quadratic nonlinear optical susceptibility in push-pull chromophores based on bridged dithienylethylene spacers

Replacement of the open chain dithienylethylene π-conjugating spacer by its bridged analog in push-pull NLO-phores produces a dramatic increase of the quadratic hyperpolarisability.