Synthesis, Properties, and Redox Behavior of Tris(1-azulenyltetracyanobutadiene) and Tris[1-azulenylbis(tetracyanobutadiene)] Chromophores Connected to a 1,3,5-Tri(1-azulenyl)benzene Core

Tris(1-azulenylacetylene) and tris(1-azulenylethynylarylacetylene) chromophores connected to a 1,3,5-tri(1-azulenyl)benzene core have been prepared by the Pd-catalyzed alkynylations of 1-ethynylazulene with tris(3-iodo-1-azulenyl)benzene or iodoarene derivatives substituted with a 1-azulenylethynyl group with tris(3-ethynyl-1-azulenyl)benzene under Sonogashira-Hagihara cross-coupling conditions. These compounds reacted with tetracyanoethylene in formal [2+2] cycloaddition-retroelectrocyclization reactions to afford the corresponding tris(1-azulenyltetracyanobutadiene) and tris[1-azulenylbis(tetracyanobutadiene)] chromophores in excellent yields. The redox behavior of the tetracyanobutadiene (TCBD) derivatives was examined by cyclic voltammetry (CV) and differential pulse voltammetry (DPV), which revealed their multistep electrochemical reduction properties. Moreover, significant color changes were observed by visible spectroscopy under the electrochemical reduction conditions.ArticleEUROPEAN JOURNAL OF ORGANIC CHEMISTRY. 2015(9):1979-1990 (2015)journal articl

Synthesis of 1,3-Bis(tetracyano-2-azulenyl-3-butadienyl)azulenes by the [2+2] Cycloaddition-Retroelectrocyclization of 1,3-Bis(azulenylethynyl)azulenes with Tetracyanoethylene

1,3-Bis(azulenylethynyl)azulene derivatives 9-14 have been prepared by palladium-catalyzed alkynylation of 1-ethynylazulene 8 with 1,3-diiodoazulene 1 or 1,3-diethynylazulene 2 with the corresponding haloazulenes 3-7 under Sonogashira-Hagihara conditions. Bis(alkynes) 9-14 reacted with tetracyanoethylene (TCNE) in a formal [2+2] cycloaddition-retroelectrocyclization reaction to afford the corresponding new bis(tetracyanobutadiene)s (bis(TCBDs)) 15-20 in excellent yields. The redox behavior of bis(TCBD)s 15-20 was examined by using CV and differential pulse voltammetry (DPV), which revealed their reversible multistage reduction properties under the electrochemical conditions. Moreover, a significant color change of alkynes 9-14 and TCBDs 15-20 was observed by visible spectroscopy under the electrochemical reduction conditions.ArticleCHEMISTRY-A EUROPEAN JOURNAL. 15(18):11903-11912 (2014)journal articl

Synthesis and Properties of Azulene-Substituted Donor-Acceptor Chromophores Connected by Arylamine Cores

1-Ethynylazulenes connected by several arylamine cores reacted with tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) in a formal [2+2] cycloaddition-cycloreversion reaction to afford the corresponding tetracyanobutadiene (TCBD) and dicyanoquinodimethane (DCNQ) chromophores, respectively, in excellent yields. The intramolecular charge-transfer (ICT) characters between the donor (azulene and arylamine cores) and acceptor (TCBD and DCNQ units) moieties were investigated by UV/Vis spectroscopy and theoretical calculations. The redox behavior of the new TCBD and DCNQ derivatives was examined by cyclic voltammetry (CV) and differential pulse voltammetry (DPV), which revealed their multistep electrochemical reduction properties. Moreover, significant color changes were observed by visible spectroscopy under the electrochemical reduction conditions.ArticleEUROPEAN JOURNAL OF ORGANIC CHEMISTRY. 2013(34):7785-7799 (2013)journal articl

Azulene-Based Donor-Acceptor Systems: Synthesis, Optical, and Electrochemical Properties

First published: 07 Aug 2017We describe the synthesis and properties of azulene-substituted 1,1,4,4-tetracyanobutadienes (AzTCBDs) and heteroazulenyl TCBDs. TCBD derivatives were prepared in good to excellent yields through reaction of the corresponding 1-ethynylazulenes with tetracyanoethylene (TCNE). In contrast, the reaction between propargyl alcohols and the 1-azulenyl group in TCNE generated 2-aminofuran derivatives, which were transformed into 6-aminofulvenes with a 1-azulenyl substituent upon treatment with several amines. The optical and electrochemical properties of the AzTCBDs were clarified by UV/Vis and voltammetry. The AzTCBD derivatives exhibited electrochromism, showing a multi-step color change under electrochemical redox conditions. The multistage redox properties of AzTCBDs could be useful for the development of novel organic electronic materials