Synthesis, Properties and Redox Behavior of Ene-Diyne Scaffolds Bearing 1- and 2-Azulenyl Groups at the Periphery

Ene-diyne systems possessing 1- and 2-azulenyl groups at the periphery were prepared by palladium-catalyzed cross-coupling reaction of 1- and 2-ethynylazulenes with 9-di-bromomethylene-9H-fluorene and 9,10-bis(dibromomethylene)-9,10-dihydroanthracene or 2-iodoazulene with 9,10-bis(diethynylmethylene)-9,10-dihydroanthracene under Sonogashira-Hagihara conditions. The redox behavior of the ene-diyne compounds was examined by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Moreover, a significant color change of the ene-diyne derivatives was observed with visible spectroscopy under electrochemical reduction conditions.ArticleEUROPEAN JOURNAL OF ORGANIC CHEMISTRY. 2013(5):957-964 (2013)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

Root tip-dependent, active riboflavin secretion by Hyoscyamus albus hairy roots under iron deficiency

Hyoscyamus albus hairy roots with/without an exogenous gene (11 clones) were established by inoculation of Agrobacterium rhizogenes. All clones cultured under iron deficient condition secreted riboflavin from root tips into the culture medium and the productivity depended on the number and size of root tips among the clones, although the addition of sucrose was essential for riboflavin production. A decline of pH was observed before riboflavin production and root development using either a root tip or propagated roots: propagated roots were employed for further work due to their lesser variation. Additions of proton-pump inhibitors, N,N’-dicyclohexylcarbodiimide (DCCD) at 100 and 10 μM and erythrosine B at 100 μM, suppressed the pH decline at 100 and 10 μM accompanied by inhibition of riboflavin secretion and root growth; at 10 μM of erythrosine B, pH decline occurred with a moderate delay, but both growth and riboflavin efflux were inhibited. Neither inhibition of the pH decline nor riboflavin production was observed at 1 μM. To examine the necessity of acidification and riboflavin secretion by the roots themselves, artificial pH reduction of culture medium with organic acids and the addition of exogenous riboflavin with/without pH reduction were performed. When hairy roots were cultured in iron-deficient medium acidified with citric acid (pH 4.0) or malic acid (pH 3.7), pH increased rapidly to around 5 overnight, following which riboflavin production and root growth occurred. Addition of riboflavin did not affect riboflavin secretion by the roots, but acidification with citric acid (pH 4.0) helped achiever greater riboflavin production and earlier pH elevation. These results indicate that riboflavin efflux does not directly connected to active pH reduction, and more significantly active riboflavin secretion occurs by internal requirement in H. albus hairy roots under iron deficiency

Synthesis, Properties, and Crystal Structure of DDQ-Adducts of Ethynylated 2H-Cyclohepta[b]furan-2-ones

Ethynylated 2H-cyclohepta[b]furan-2-ones reacted with 2,3-dichrolo-5,6-dicyano-1,4-benzoquinone (DDQ) in a formal [2+2] cycloaddition reaction to afford the corresponding DDQ-adducts in good yields. The electronic properties of the DDQ-adducts were investigated by UV/Vis spectroscopy. One of the DDQ-adducts was revealed the molecular structure by X-ray crystallographic analysis. The redox behavior of the new compounds was examined by cyclic voltammetry (CV) and differential pulse voltammetry (DPV).ArticleHETEROCYCLES. 88(1):319-329 (2014)journal articl

Synthesis of Novel Thiophene-Fused 1,1’-Biazulene Derivative by the Reaction of Azuleno[1,2-b]thiophene with N-Iodosuccinimide

Novel thiophene-fused 1,1'-biazulene derivative was prepared by the reaction of azuleno[1,2-b]thiophene with N-iodosuccinimide. The electronic properties of the new 1,1'-biazulene derivative obtained by the reaction were characterized by CV, DPV, and UV/Vis spectroscopy.ArticleHETEROCYCLES. 87(2):303-306 (2013)journal articl

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 Novel Thiophene-Fused 1,1’-Biazulene Derivative by the Reaction of Azuleno[1,2-b]thiophene with N-Iodosuccinimide

Novel thiophene-fused 1,1'-biazulene derivative was prepared by the reaction of azuleno[1,2-b]thiophene with N-iodosuccinimide. The electronic properties of the new 1,1'-biazulene derivative obtained by the reaction were characterized by CV, DPV, and UV/Vis spectroscopy.ArticleHETEROCYCLES. 87(2):303-306 (2013)journal articl

Synthesis and Properties of (3-Phenyl-1-azulenyl) tetracyanobetadienes and Tris(aryltetracyanobetadiene) s Connected with 1,3,5-Tri(1-azulenyl) benzene Core

Tris[(3-phenyl-1-azulenyl) tetracyanobutadiene] s and tris(arylte-tracyanobutadiene) s connected to a 1,3,5-tri(1-azulenyl) benzene core (tris-AzTCBDs) have been prepared by the Pd-catalyzed alkynylation of tris(3-iodo-1-azulenyl) benzene derivative with the corresponding 1-ethynylazulene or ethynylbenzene derivatives under Sonogashira-Hagihara cross-coupling conditions, followed by the reaction with tetracyanoethylene (TCNE) in a formal [ 2 + 2] cycloaddition-retroelectrocyclization (CA-RE) reaction. The intramolecular charge-transfer (ICT) interactions of the new chromophores were investigated by the comparison with those of the model tetracyanobutadiene de-rivatives with azulene substituents (AzTCBDs), which were prepared by the reaction of the corresponding 1-ethynylazulene derivative with iodoarenes, followed by the CA-RE reaction with TCNE, utilizing UV/Vis spectroscopy and theoretical calculations. The redox behavior of the alkyne precursors and the tetracyanobutadiene derivatives was examined by cyclic voltammetry (CV) and differential pulse voltammetry (DPV), which revealed their multistep electrochemical reduction properties. Moreover, significant color changes of these compounds were observed by visible spectroscopy under the electrochemical reduction conditions.ArticleCHEMISTRYSELECT. 9:49-57 (2016)journal articl

Synthesis, Properties, and Redox Behavior of Tetracyanobutadiene and Dicyanoquinodimethane Chromophores Bearing Two Azulenyl Substituents

Acetylene derivatives with an azulenyl group at both terminals have been prepared by palladium-catalyzed alkynylation under Sonogashira–Hagihara conditions. These alkynes reacted with tetracyanoethylene and 7,7,8,8-tetracyanoquinodimethane in a formal [2 + 2] cycloaddition–retroelectrocyclization reaction to afford the corresponding new tetracyanobutadienes (TCBDs) and dicyanoquinodimethanes (DCNQs), respectively, in excellent yields. Intramolecular CT absorption bands were found in the UV–vis spectra of the novel chromophores, and CV and DPV showed that they exhibited a reversible two-stage reduction wave, due to the electrochemical reduction of TCBD and DCNQ moieties. Color changes were also observed during the electrochemical reduction