Formation of H aggregates of thionine dye in water

Lai, Wen-Chao; Dixit, Namrata; Mackay, Raymond A.

doi:10.1021/j150666a051

Cited by 55 publications

(39 citation statements)

References 2 publications

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“…The experimentally observed spectral shift in water as a function of concentration resulted in an aggregate band hypsochromic, with the aggregate being formed by the association of dye molecules in which the molecules were arranged one above the other [11,23]. Similar results have been reported by other authors for Thionine, a thiazine dye [24]. Since the spectral changes upon aggregation are dependent in many ways on the properties of the isolated molecule, the degree of spectral changes is not a direct indication of the degree of aggregation [25].…”

Section: Resultssupporting

confidence: 87%

Spectroscopic characterization and aggregation of azine compounds in different media

Urrutia¹,

Ortiz²

2013

Chemical Physics

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In this study, we have reported for the first time a complete experimental investigation on the compound Neutral Red and the new monobrominated derivative in different media as a function of the concentration. These compounds belong to the quinone-imine class of dyes and have good potential to be applied as photosensitizers in Photodynamic Therapy.Although the aggregation of Neutral Red has been reported by several authors, this has not been thoroughly evaluated due to spectral changes occurring depending on the solvent and concentration of dye.

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Section: Resultssupporting

confidence: 87%

Spectroscopic characterization and aggregation of azine compounds in different media

Urrutia¹,

Ortiz²

2013

Chemical Physics

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“…587 and 564 nm, due to 0 ← 0, 1 ← 0, and 2 ← 0 π* ← π transitions. 54 Looking at the ZL/ 0.15Th and ZL/0.27Th composites (b, green curve, and c, blue curve, respectively), the absorption spectra appear almost coincident each other in position and shape, indicating Th molecules basically experience the same environment independently of the loading, which actually is rather low in both cases. Interestingly, the spectral profile of both composites exhibits a similar shape with respect to Th molecules in solution but appeared red-shifted by 17 nm, indicating that the entrapment in the host affected the electronic states of the dye guest.…”

Section: Resultsmentioning

confidence: 93%

Thionine Dye Confined in Zeolite L: Synthesis Location and Optical Properties

et al. 2015

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The process of light conversion is at present deeply investigated to develop more efficient devices for artificial photosynthesis, water splitting, photovoltaic applications, and targeting therapeutic agents. This process is induced by nanostructured functional materials, such as zeolites light sensitized by dye molecules adsorbed into their pores. Here a detailed study of the organization of the cationic dye thionine (Th) inserted into the linear 12MR channels of zeolite L is carried out by XRPD, FT-IR spectroscopyfor the determination of the host−guest interactionsand UV−vis absorption and photoluminescence spectroscopies for the investigation of the electronic states of the guest. Two composites with different Th loading (labeled ZL/0.15Th and ZL/0.27Th) were obtained through ion exchange. TGA spectra and IR-ATR spectroscopy clearly indicated penetration of Th molecules into the ZL channels. Rietveld structural refinement showed that Th molecules in both composites are aligned parallel to the 12MR channel axis and located on the mirror planes parallel to the c-axis. Water molecules interact strongly with the dye and form a kind of solvent−matrix tube shaped around the Th molecule, favoring the upright arrangement of the molecules. DR−UV−vis spectra of the ZL/Th composites indicated that Th molecules are hosted in the ZL channels in a monomeric form. Photoluminescence spectroscopy demonstrated that photoluminescent dyes correspond to ca. 5% of the total amount of Th molecules in the zeolite porosities. While most of the photoluminescent Th molecules exhibit a lifetime equivalent to Th in solutions, the complementary fraction of photoluminescent Th exhibit significantly longer lifetimes, resulting from an entrapment in defects of the zeolite structure, inducing strong rotational constraints to the molecules.

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“…16,31 Increasing the concentration of MO does, however, result in a blue shift of the long wavelength absorption band. 16 On the other hand, dyes like thionine 32 and methylene blue 33 are known to aggregate in aqueous solution, resulting in the appearance of a blue-shifted aggregate band.…”

Section: Resultsmentioning

confidence: 99%

Aggregation of Azo Dyes with Cationic Amphiphiles at Low Concentrations in Aqueous Solution

1999

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The aggregation of a series of n-alkyltrimethylammonium bromide (C n TAB, n = 10, 12, 14, 16, and 18) and 4-n-alkyl-1-methylpyridinium iodide amphiphiles (C m pyI, m = 8, 10, 12, and 14) induced by low concentrations of azo dyes in aqueous solution has been investigated by means of ultraviolet (UV) spectroscopy. It was observed that aggregation takes place at surfactant concentrations far below the cmc of C12TAB, C14TAB, C16TAB, and C18TAB with methyl orange (MO), ethyl orange (EO), and para-methyl red (pMR). Aggregation below the cmc of C10TAB was also induced by EO. In the case of MO and pMR, however, higher dye concentrations were necessary to induce aggregation. Interactions at low surfactant concentrations have also been observed in aqueous solutions of C10pyI, C12pyI, and C14pyI with MO. Binding of methyl red (MR), methyl yellow (MY), and azobenzene sulfonate (ABS) with cationic surfactants below their cmc did not occur. Aggregation was reflected by the appearance of a blue-shifted absorption band in the spectra of the dyes. Precipitates formed in aqueous solutions from the cationic surfactants and MO and pMR are C n TA−MO, C n TA−pMR, and C m py−MO salts and consist of an equimolar ratio of surfactant and dye. In similar experiments with EO, MR, MY, or ABS as the solvatochromic dye molecules, no precipitation occurred, although surfactant−EO salts precipitated at high EO concentration. Dye−surfactant salts formed from C n TAB and MO were found to form myelins in phase penetration experiments. Temperatures at which myelins start to form increase upon increasing alkyl chain length of the surfactant as revealed by optical microscopy. The formation of vesicles from C10TA−MO and from C12TA−MO crystals was indicated by electron microscopy. The presence and position of the ionic group in the dye molecule is important in determining the association. The importance of hydrophobic interactions is revealed by the chain length dependence on the aggregation process and the observation that interactions are absent in ethanol. Electrostatic interactions also play an important role, as shown by the effect of NaCl on the binding process.

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Formation of H aggregates of thionine dye in water

Cited by 55 publications

References 2 publications

Spectroscopic characterization and aggregation of azine compounds in different media

Spectroscopic characterization and aggregation of azine compounds in different media

Thionine Dye Confined in Zeolite L: Synthesis Location and Optical Properties

Aggregation of Azo Dyes with Cationic Amphiphiles at Low Concentrations in Aqueous Solution

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