New push-pull dyes based on 2-(3-oxo-2,3-dihydro-1H-cyclopenta[b]naphthalen-1-ylidene)malononitrile: An amine-directed synthesis

Abstract

A series of twelve dyes have been designed using 2-(3-oxo-2,3-dihydro-1H-cyclopenta[b]naphthalen-1-ylidene)malononitrile as the electron acceptor. While using piperidine as a classical base for the Knoevenagel reaction, a nucleophilic attack of the amine on the formed push-pull chromophore occurred, producing an azafluorenone derivative. By varying the amine, a series of azafluorenones could be obtained. By using an aldehyde of extended conjugation, a spontaneous aromatization following the cyclization reaction could also be demonstrated. The optical, electrochemical properties of the different dyes were examined. Theoretical calculations were also carried out to support the experimental results.

Recent advances on pyrene-based photoinitiators of polymerization

“…coefficients. [166][167][168][169][170][171] These results were confirmed the same year by another study devoted to Pyr_30 and…”

New Donor-Acceptor Stenhouse Adducts as Visible and Near Infrared Light Polymerization Photoinitiators

“…When using the same reaction conditions used with PP7 and diethylamine, Read de Alaniz and coworkers reported a nucleophilic attack of piperidine on the cyano groups of PP7, producing the cyclization product CP1 in 96% yield as the only reaction product according to the mechanism presented in Scheme 6. It should be noticed that the nucleophilic addition of secondary amines onto the cyano groups of push-pull dyes has been recently reported in the literature as a side-reaction occurring during the synthesis of push-pull dyes comprising EA3 or EA4 as the electron acceptors [56][57][58][59][60]. The preferential nucleophilic addition of diethylamine on cyano groups rather than onto the electrodeficient furyl group was confirmed during the synthesis of PP25 starting from PP7 and diethylamine (A1).…”

Synthesis, and the optical and electrochemical properties of a series of push–pull dyes based on the 4-(9-ethyl-9H-carbazol-3-yl)-4-phenylbuta-1,3-dienyl donor

“…Besides, the steric hindrance induced by the use of asymmetric electron acceptors such as EA2 and EA5 certainly favour an orientation over the other. It has to be noticed that among the twelve electron acceptors issued in this study, EA2 81 , EA3 82 , EA4 83 , EA5 76 , EA11 84 and EA12 85 had to be prepared.…”

“…In the case of dyes B and E, choice of DIPA as the base was motivated by recent results reported in the literature mentioning a nucleophilic attack of secondary amines on the cyano groups of EA5, inducing a cyclization reaction and producing azafluorenone derivatives. [76][77][78][79][80] However, piperidine could be used for the synthesis of dye M, no nucleophilic attack of amine being reported at present in the literature for EA11. Finally, dye F was prepared by using a specific procedure.…”