6537-68-4Relevant articles and documents
Excited-state isomerization of leuco indigo
Rondao,Seixas De Melo,Melo,Parola
, p. 2826 - 2832 (2012)
The photoreaction of indigo and two other derivatives in its reduced (leuco) form was investigated by absorption and fluorescence (steady-state and time-resolved) techniques. The fluorescence quantum yield (φF) dependence with the UV irradiation time was found to increase up to a value of φF ≈ 0.2-0.3 (after 16 min) for indigo and φF = 0.2 (at ～150 min) for its derivative 4,4′-dibutoxy-7,7′- dimethoxy-5,5′-dinitroindigo (DBMNI). With a model compound, where rotation around the central C-C bond is blocked, the φF value was found constant with the UV irradiation time. Time-resolved fluorescence revealed that initially the decays are fitted with a biexponential law (with 0.12 and 2.17 ns), ending with an almost monoexponential decay (～2.17 ns). Quantum yields for the isomerization photoreaction (φR) were also obtained for indigo and DBMNI with values of 0.9 and 0.007, respectively. The results are rationalized in terms of a photoisomerization (conversion) reaction occurring in the first excited singlet state of trans to cis forms of leuco indigo.
5,5′-alkylsubsituted indigo for solution-processed optoelectronic devices
Watanabe, Motonori,Uemura, Naoki,Ida, Shintaro,Hagiwara, Hidehisa,Goto, Kenta,Ishihara, Tatsumi
, p. 4280 - 4287 (2016/07/06)
A series of alkylated indigos were synthesized. Alkylated indigos were characterized by NMR, mass spectrometry, absorption spectra, cyclic voltammetry, and density functional theory (DFT) calculations. Propyl and butyl group substituted indigo was most soluble in chloroform and 1,2-dicrolobenzene, and these solubility were 65–89 times increased as compared to the parent indigo. DFT calculations suggested that the presence of the alkyl chains at the 5.5′-position increases the energy of the highest occupied molecular orbital, while reducing the energy of the lowest unoccupied molecular orbital. This theoretical finding was in good agreement with the experimental results. Crystal structures obtained by X-ray diffraction showed one-dimensional pi–pi stacking. Alkylated molecules were converted to leuco structure, and these structures were then converted to the corresponding indigos in the film state. After deposition of the films on TiO2/FTO substrate, oxidative photocurrents were observed.
Maya Blue as a nanostructured polyfunctional hybrid organic-inorganic material: The need to change paradigms
Domenech, Antonio,Domenech-Carbo, Maria Teresa,Sanchez Del Rio, Manuel,Vazquez De Agredos Pascual, Maria Luisa,Lima, Enrique
scheme or table, p. 2371 - 2379 (2010/03/04)
Maya Blue, an ancient nanostructured organic-inorganic hybrid material resulting from the attachment of indigo, a natural dye, to a phyllosilicate clay, palygorskite, has received considerable attention of late. Despite intensive research, several aspects
