Fluorene acceptors with intramolecular charge-transfer from 1,3-dithiole donor moieties: novel electron transport materials

Unprecedented Nucleophilic Attack of Piperidine on the Electron Acceptor during the Synthesis of Push‐Pull Dyes by a Knoevenagel Reaction

“…As a result of this, Napht‐EA is less acceptor in PP1 than in PP2 due to the closer proximity of the electron donating group, adversely affecting its electron‐withdrawing ability. Generally, the opposite trend consisting in a cathodic shift of the reduction potential with elongation of the π ‐conjugated length is reported in the literature . Remarkable examples of this were notably reported with strong electron acceptors such as poly(nitrofluorene) .…”

“…Generally, the opposite trend consisting in a cathodic shift of the reduction potential with elongation of the π-conjugated length is reported in the literature. [32] Remarkable examples of this were notably reported with strong electron acceptors such as poly(nitrofluorene). [33] However, in these different works, the LUMO level doesn't extend over the whole molecule, and HOMO and LUMO levels respectively centered onto the electron donor and the electron acceptor are observed.…”

Combining High Electron Affinity and Intramolecular Charge Transfer in 1,3‐Dithiole–Nitrofluorene Push–Pull Diads

“…[20,[23][24][25] As strong CÀH acids, [26] derivatives 4 a-g readily participate in condensation reactions with various electrophiles, which include aldehydes, [4b, 27] amides, [26] and dithiolium salts. [20,21,28] Thus, treatment of nitrosubstituted fluorenes 4 a-g with dithiolium salts www.chemeurj.org 3 A-F, which were obtained by methylation of the corresponding 1,3-dithiol-2-thiones 2 A-F with methyl trifluorosulphonate, [29] results in the formation of 9-(1,3-dithiol-2-ylidene)fluorenes 6-11 (Scheme 1). The reaction proceeds smoothly in N,N-dimethylformamide (DMF) with no additional catalyst (in contrast with common base-catalysed reactions of activated methylene compounds) and its rate positively correlates with the electron-withdrawing strength of substituents in the fluorene nucleus.…”

“…X-ray crystallography: To assess the structural variations in fluorene-dithiolylidene diads, we performed X-ray crystallographic studies on derivatives 7 a, 8 a (briefly reported earlier [21] ), 10 a, 11 a and 13 a ( Figure 6) with the same (2,4,5,7-tetranitro-) substitution in the fluorene acceptor moiety and varied 4,5-substituents in the dithiole donor moiety. These Table 3.…”

“…[20,21] The present work describes the synthesis and detailed studies of the structural effects in both fluorene and dithiole rings on the spectral and electrochemical properties of these new donor-acceptor diads, as well as on their supramolecular organisation in the solid state. Electrochemical and spectroscopic data have been supported by theoretical DFT calculations.…”