Formation of nano‐dots of phenylazomethine dendrimers with Rhodamine 6G on mica

The phenylazomethine dendrimer (DPA) is associated with Rhodamine 6G in chloroform, which results in the chemical shift attributed to the aromatic protons of phenylazomethine being moved upfield in the ¹H‐NMR spectrum by increasing the Rhodamine 6G. The shift is saturated at the ratio of 1 : 1. On the basis of the NMR analysis, the association constant K of phenylazomethine with Rhodamine 6G was determined to be 1.4 × 10⁴ (l/mol) in CDCl₃ at 20°C. The association is also confirmed by UV‐vis spectroscopy, in which the absorption around 450 and 527 nm changes during the addition of Rhodamine 6G. The fluorescence intensity of the 1 : 1 complex of Rhodamine 6G and DPA G4 is stronger than that of the solution dissolved only in Rhodamine 6G at greater than 1 mM though it is generally known that the intermolecular interaction quenches the dye fluorescence in a concentrated solution. The association of DPA G4 with Rhodamine 6G suppresses the quenching at higher concentrations. Homogenous nano‐dots were observed on mica by casting the DPA G4 complex with Rhodamine 6G, in which the height and average area were 1.5–3 nm and 1.6 × 10³ nm² (the standard deviation σ = 3.7 nm²), respectively. Copyright © 2004 John Wiley & Sons, Ltd.     

Active media based on SiO2 matrices with incorporated molecules of rhodamine dyes

SiO₂ matrices with incorporated molecules of Rhodamine 6G and Rhodamine 800 laser dyes were synthesized by the sol?Cgel method. The spectral properties of the matrices were studied. It was found that the incorporation of Rhodamine 6G molecules into the xerogel network decreased their association. The influence of the molar ratio of water and formamide on the transparency of the samples was studied. Laser emission of SiO₂ matrices activated with Rhodamine 800 was obtained in the near infrared spectral range. The values of laser spectrum halfwidth of SiO₂ matrices with Rhodamine 6G and Rhodamine 800 are 2?C6?nm. A well-defined structure of the laser emission spectra of the matrices at microsecond pumping duration testifies to their relatively high optical quality.     

新型以若丹明染料为母体的三发色团化合物的荧光性能

若丹明染料作为一种重要的激光染料,它们具有较高的荧光量子效率。这类染料在紫外区的吸收是相当小的,于是,当它们被使用在横向泵浦激光装置上时,就需要相当高的染料浓度,这样才能有效地吸收紫外泵浦光(如XeCI激光器,308 nm)。问题是,这类染料的发射光谱与其吸收光谱的低能量部分有重叠,亦即它门的Stokes位移较小,并且由于染料的荧光量子效率通常小于100,以致使一部分染料的激发辐射被基态染料分子再吸收,从而导致激发辐射的损失。与此同时,为了有效吸收泵浦光能量,染料的浓度通常很高,这样,激发辐射损失就会相当大。     

Electron-impact and thermal degradation of Rhodamine F5G chloride and related compounds

The mass spectra and thermal decomposition of Rhodamine F5G hydrochloride have been studied in detail. Fragmentation schemes are presented which show that fragmentation in the mass spectrometer involves principally the substituents on the 9-phenylxanthhydrol nucleus. Mass spectral studies of the related compounds Rhodamine B500 hydrochloride, Rhodamine F5G hydroxide and Rhodamine F5G dihydrogen phosphate are also reported. The thermal decomposition of Rhodamine F5G hydrochloride leads to initial loss of ethyl chloride and formation of the zwitterion which rearranges at higher temperature to a lactone. The further pyrolysis has also been studied.     

Photo-Induced Intermolecular Electron Transfer-Effect of Acceptor Molecular Structures

Photo-induced electron transfer versus molecular structure of acceptors is investigated using ultrafast time-resolved transient grating spectroscopy. Typical laser dyes Rhodamine 101 (Rh101) and Rhodamine 6G (Rh6G) in electron donor solvent-aniline are adopted as the objects. The forward electron transfer time constant from aniline to the excited singlet state of two Rhodamine dyes and subsequent back electron transfer from two dyes to aniline are measured. The experimental results denote that Rh6G presents faster electron transfer rates with aniline in both forward electron transfer and back electron transfer processes. With chemical calculation and qualitative analysis, it is found that the flexible molecular geometry of Rh6G leads to stronger electron coupling with donor solvent and further gives rise to larger electron transfer rates.     

吖啶橙—罗丹明6G—罗丹明B组合成各种混合染料体系的能量转移研究

本文对吖啶橙－罗丹明６Ｇ－罗丹明Ｂ组合成各种混合染料体系的能量转移进行了研究。结果表明，在十二烷基硫酸钠的水溶液中，吖啶橙－罗丹明６Ｇ间，罗丹明６Ｇ－；罗丹明Ｂ间，吖啶橙－罗丹明Ｂ间均能发生有效的能量转移。可以认为不仅染料单体，而且二聚体也是能量转移效率的竞争，探讨了表面活性剂对能量转移的影响。本文的工作将有助于拓宽能量转移的理论研究和应用范围。     

A simple strategy for constructing acylhydrazone photochromic system with visible color/emission change and its application in photo-patterning

As a potential photochromic system, acylhydrazones exhibit many outstanding advantages including low cost, simple synthesis and high modifiability compared with some classic photochromic systems. However, the absorptionwavelengths of acylhydrazones usually locate in ultraviolet region, which makes the band separation between the absorbance maxima of its irradiated and unirradiated forms cannot be observed by naked eyes and greatly limits their practical applications. In this work, a simple strategy for constructing acylhydrazone photochromic system with visible color/emission change is provided. Rhodamine 6G hydrazine-2-aldehyde-pyridine Schiff base (compound 3) is designed and synthesized by combining acylhydrazone with Rhodamine 6G structure. The introduction of Rhodamine 6G moiety to 3 not only makes it remain all the advantages of acylhydrazone photochromic system but also exhibits visible photo-induced color/emission changes both in solution and in a solid matrix. Moreover, 3 exhibits reversible photochromic property with good fatigue resistance, which makes it an excellent candidate for photo-patterning.     

Diffusion of isolated surface-active molecules at the air/water interface

Fluorescence correlation spectroscopy was applied to study the diffusion of isolated surface-active molecules at air/water interfaces. Rhodamine 6G was used as a surface-active fluorescent tracer. Results show that the diffusion coefficient of the Rhodamine 6G at the interface is about 2.5 times higher than in the bulk. Effects of Rhodamine 6G concentration and added SDS or CTAB surfactants have been studied. Diffusion of Rhodamine 6G at the interface is slowed down at surfactant concentration corresponding to a mean distance between molecules of 10 and 40 nm, indicating a long-range interaction.     

A simple strategy for constructing acylhydrazone photochromic system with visible color/emission change and its application in photo-patterning

As a potential photochromic system, acylhydrazones exhibit many outstanding advantages including low cost, simple synthesis and high modifiability compared with some classic photochromic systems. However, the absorption wavelengths of acylhydrazones usually locate in ultraviolet region, which makes the band separation between the absorbance maxima of its irradiated and unirradiated forms cannot be observed by naked eyes and greatly limits their practical applications. In this work, a simple strategy for constructing acylhydrazone photochromic system with visible color/emission change is provided. Rhodamine 6G hydrazine-2-aldehyde-pyridine Schiff base (compound 3) is designed and synthesized by combining acylhydrazone with Rhodamine 6G structure. The introduction of Rhodamine 6G moiety to 3 not only makes it remain all the advantages of acylhydrazone photochromic system but also exhibits visible photo-induced color/emission changes both in solution and in a solid matrix. Moreover, 3 exhibits reversible photochromic property with good fatigue resistance, which makes it an excellent candidate for photo-patterning.     

银纳米微球和银纳米棒自组装膜的制备及SERS研究

采用硼氢化钠还原硝酸银,用振荡器在不同转速下振荡得到单分散的银纳米微球和银纳米棒,再将银纳米微球及银纳米棒自组装于被3-氨丙基-三甲氧基硅烷(APTMS)修饰的玻璃基片上,制得了具有表面增强拉曼(SERS)活性的基底,分别以罗丹明6G(R6G)和罗丹明B(RB)为探针分子对这两种基底进行SERS活性检测,结果发现这两种基底均为较理想的SERS衬底。     

Interaction of phospholipids with rhodamine 6G in toluene.

Upon interaction of various glycerophospholipids with Rhodamine 6G in toluene, a typical difference spectrum with an absorption maximum at approximately 515 nm is obtained . This spectrum is obtained with phosphatidylcholine only after treatment with NaCl, which presumably weakens intra- and/or inter-molecular electrostatic binding between the negatively charged phosphate moiety and the protonated nitrogen in this molecule. Absorption at 515 nm was linear for all of the phospholipids investigated from a concentration of approximately 1.2 microM up to at least 50 microM. The highest extinction coefficient was obtained for diphosphatidylglycerol (251 mM-1 cm-1) and all of the compounds tested, with the exception of phosphatidylethanolamine, demonstrated extinction coefficients higher than that of palmitic acid. Thus, the absorption spectrum which results from the interaction of purified glycerophospholipids with Rhodamine 6G in organic solvent is a sensitive measure of the amount of phospholipid present.     

Poly(ethyl cyanoacrylate) colloidal particles tagged with Rhodamine 6G: preparation and physicochemical characterization

This paper describes the preparation and characterization of poly(ethyl cyanoacrylate) colloidal particles loaded with the organic fluorophore Rhodamine 6G. We studied the physicochemical properties of the colloidal particles: morphology, size-distribution, ζ-potential, fluorescent properties and photobleaching upon UV-light illumination. The properties of the obtained colloidal particles, as well as the dye loading efficiency, were found to depend on the concentrations of ethyl cyanoacrylate monomer and Rhodamine 6G in the polymerization medium. The fluorophore release from the colloidal particles in aqueous buffer is also studied.      

Wastewater purification to remove dyes with monocation-substituted forms of bentonite and flocculants-coagulants

Possibility of performing sorption-coagulation purification of model wastewater to remove cationactive dyes (Rhodamine G, Methylene blue, thionine, and fuchsine) with bentonite sorbents and Gyanja flocculant-coagulant was studied. The effect of the nature and charge of exchange cations on the sorptioncoagulation capacity of bentonite samples was examined.     

罗丹明6G的荧光光谱

在苯-甲醇混合溶剂中测量了罗丹明6G的吸收光谱和荧光光谱,发现体系中荧光强度和光密度随甲醇浓度的增长而增长.这可解释为甲醇浓度增加,溶液的介电常数也增加,这样自由离子浓度增加,未解离分子浓度减少.结果表明无论由吸收光谱和由荧光光谱都说明荧光来源于R6G离子.     

Excitation Energy Transfer from Semi‐Conducting Polymer Nanoparticles to Surface‐Bound Fluorescent Dyes

Summary: The first examples of the dye‐coated semi‐conducting polymer nanoparticles as well as experiments to demonstrate the excitation energy transfer from the excited chromophor of the nanoparticle to the fluorescent dye are described. We have demonstrated that the blue fluorescence of the dye‐coated polyfluorene nanoparticles is only slightly quenched after dye deposition. However, a new emission band of the surface‐bound dye (Rhodamine 6G or Rhodamine TM) appears in the wavelength region of 530–600 nm. These results clearly indicate an effective excitation energy transfer from the excited PF chromophores to the fluorescent dye.

Emission spectra of PF2/6 nanoparticle dispersion and of Rhodamine 6G‐coated nanoparticle dispersion.     

Molecular sensing with ultrafine silver crystals on hexagonal aluminum nitride nanorod templates

A fully plasma-based technique of generating ultrafine (sub-10-nm) nanocrystalline silver particulates on wide band gap and chemically inert hexagonal aluminum nitride nanorod templates has been demonstrated. These specially prepared substrates are ready to use for molecular sensing by room-temperature surface-enhanced Raman scattering. An enhancement factor of 2 x 106 was observed for micromolar solutions of Rhodamine 6G.     

On-line preconcentration of phosphate onto molybdate form anion exchange column

In this paper, we describe an automated flow injection system for measuring the concentration of phosphate based on a fluorescence quenching reaction between Rhoadamine 6G and phosphomolybdate with a preconcentration column, which was packed with a molybdate-form ion exchange resin to collect and preconcentrate the phosphate in the sample solution. Rhodamine 6G was chosen because the reaction with phosphomolybdate was fast and did not require heat. For the construction of a stable flow injection system, an aqueous methanol solution was used as the cleaning reagent to overcome the precipitation of ion-associated complexes between Rhodamine 6G and phosphomolybdate or Rhodamine 6G and molybdate. For the preconcentration and collection of the phosphate ions in a water sample, a preconcentration column, which was packed with a molybdate-form ion exchange resin, was combined with the proposed flow injection system and applied to natural water samples containing low concentrations of phosphate.     

A new ion sensor based on fiber optics

A fluorimetric ion sensor based on fiber optics has been developed that employs Rhodamine 6G hydrophobically and electrostatically "trapped" on a Nafion film. The sensor is based on the measurement of quenching or enhancement of the Rhodamine 6G fluorescence by various ions. It was found that ions such as Co(2+), Cr(3+), Fe(2+), Fe(3+), Cu(2+), Ni(2+) and NH(+)(4) rapidly quench the Rhodamine 6G fluorescence at an initial rate that depends on the concentration of the ion. This quenching is then readily reversed by the addition of "reverser" ions such as H(+), Li(+), Na(+), K(+), Ba(2+), Ca(2+), Mn(2+), Zn(2+) and Mg(2+). Again, the initial rate for the attainment of the original fluorescence was found to depend on the concentration of the reverser ion. Therefore, by monitoring the quenching directly the concentration of quencher ions can be determined. In addition, by loading the film with quencher and monitoring the initial rate of return towards the original baseline signal, it is possible to determine non-quenching ions.     

AGGREGATION CHARACTERISTICS OF LASER DYE RHODAMINE 6G IN AQUEOUS SURFACTANT SOLUTIONS

Abstract— –The role of surfactants as deaggregating agents for the laser dyes is investigated by spectrophotometry using Rhodamine 6G as a representative. A method to estimate the fraction of dye present as monomer, dimer and as a monomer-surfactant (monomer or micelle) complex is described. It is shown that among the surfactants, cetyl trimethyl ammonium bromide, Triton X-100, sodium lauryl sulfate (SLS) and potassium oleate, the anionic ones are the most effective in suppressing the aggregation of Rhodamine 6G. While the non-ionic surfactant is found to be effective only above its critical micellar concentration, the cationic surfactant has no effect on aggregation. The optimum concentration of SLS needed for suppression of dye-dimers is estimated.