Spectroelectrochemical Investigation on Neutral Red

Neutral Red can be used as an indicator, a stain reagent or a mediator compound in the studies of biological redox systems. No reports dealing with the electrode process of Neutral Red, especially, about its kinetics have been published. In this paper we report the determinations of formal reduction potentials, the number of electrons transferred, diffusion coefficient as well as the rate constant of heterogeneous electron transfer     

中性红作试剂荧光光度法测定亚硝酸根

研究了在盐酸介质中ＮＯ＾－２与中性红的亚硝化反应。结果表明，在０．０４８ｍｏｌ／Ｌ的盐酸介质中，ＮＯ＾－２与中性红反应生成无荧光的物质，ＮＯ＾－２在４０－２４０μｇ／Ｌ，范围内与荧光猝灭程度成正比，常见的共存离子不干扰其测定。所拟方法用于水样中ＮＯ＾－２的测定，结果满意。     

Electrochromism and Solvatochromism

The position and the intensity of electronic bands are influenced by an electric field. Pronounced changes in the position of absorption bands are mainly due to the dipole moment of the molecule in the ground state and the change in the dipole moment during the excitation process, and pronounced changes in intensity are due to the field dependence of the transition moment, which can be described by the transition polarizability. The effect of an external electric field on the optical absorption (electrochromism) of suitable molecules can be used to determine the dipole moment in the ground state, the change in dipole moment during the excitation process, the direction of the transition moment of the electronic band, and certain components of the transition polarizability tensor. These data largely determine the strong solvatochromism (solvent-dependence of the position and intensity of electronic bands), which is observed in particular with molecules having large dipole moments. Smaller contributions to solvatochromism result from dispersion interactions, which predominate in the case of nonpolar molecules. The models developed have been experimentally checked and verified by a combination of electro-optical absorption measurements (influence of an external electric field on absorption) and investigation of the solvent-dependence of the electronic bands.     

Photophysical Properties of the Cationic Form of Neutral Red

Abstract— Photophysical properties of the cationic form of neutral red (NRH⁺), a phenazine-based dye of biological importance, have been investigated in several protic and aprotic solvents using optical absorption, steady-state and time-resolved fluorescence and picosecond laser flash photolysis techniques. Absorption and fluorescence characteristics of the dye in protic solvents indicate the existence of intermolecular hydrogen bonding between the NRH⁺ and solvent molecules in the ground state as well as in the excited state. Measurements of the fluorescence lifetime in normal and heavy water also support the formation of intermolecular hydrogen bonding. Time-resolved transient absorption spectra obtained in the picosecond laser flash photolysis experiments show only the absorption band due to the S_n← S₁ absorption. The picosecond transient absorption results do not indicate any spectral shifts attributable to the hydrogen bond formation dynamics between the excited NRH⁺ and the protic solvent molecules. It is inferred that the hydrogen bonding dynamics are much faster than the time resolution of our picosecond setup (∼35 ps).     

中性介质中中性红与双链DNA作用的光谱

通过分子吸收、荧光发射和共振光散射测定,表征了在水溶液介质中中性红(NR)与双 螺旋DNA的作用.在pH 7.63和离子强度低于0.01的水溶液介质中,随着NR与DNA的摩尔比(R)变 化,存在有两种结合方式.第一种结合方式发生在R > 2.22,此时获得共振光散射光谱增强信 号,表明NR在DNA分子表面发生聚集,集聚特性可使用RLS测定数据进行Scatchard分析;第二种 结合方式发生在R < 2.22,此时NR内嵌到DNA分子的双链碱基对之间,具有特征波长红移和分 子吸收增色效应,发生了从DNA到NR的分子能量转移,能观察到荧光增强.     

Solvent effect on the spectral properties of Neutral Red

Background  

The study was aimed at investigating the effect of various solvents on the absorption spectra of Neutral Red, a dye belonging to the quinone-imine class of dyes. The solvents chosen for the study were water, ethanol, acetonitrile, acetone, propan-1-ol, chloroform, nitrobenzene, ethyleneglycol, acetic acid, DMSO and DMF.     

New Method for Determining H-Bond Energy: Fluorescence from Neutral Red in Water Compared to Fluorescence from Neutral Red in Benzene

A new method is presented for determining the H-bond energy between a fluorescent solute and water. In the current example the hydrogen-bond energy between neutral red (NR) and water was measured. The H-bond energy was obtained from the temperature dependence of the ratio of the 625 nm fluorescence intensity from NR in water, which increases with increasing temperature, to that of the 530 nm intensity from NR in benzene, which decreases with increasing temperature. The H-bond energy so determined is (10050 ± 60) J-mol⁻¹, which compares favorably with an H-bond E_HB value for pure water of 10170 J-mol⁻¹. Intermolecular hydrogen-bonding between water and NR increases the nonradiative deactivation process of the excited molecule due to fast energy dissipation through the vibrations associated with the hydrogen bonds. Some of the hydrogen bonds are broken with an increase in temperature, resulting in an increase in the number of free NR molecules, thus increasing the fluorescence quantum yield.     

用中性红分光光度法测定亚硝酸根的研究

本文研究了中性红与亚硝酸根在盐酸介质中的亚硝化反应,并由此建立了一个简单、快速、选择性好的测定亚硝酸根的新方法,该法对比耳定理的适应范围是0～0.6μg NO_2~-/ml。将本法应用于水样中亚硝酸根的测定,取得了满意的效果。     

氧化褪色光度法测定碘酸根

碘是具有生理活性的元素.食品中碘的测定常用铬酸钾氧化比色法[1],此法要用有机氯仿萃取,费时且灵敏度不高.也有动力学法[2-4]测定,其灵敏度高 ,但重现性较差.     

酵母核糖核酸与中性红相互作用及电化学检测

采用循环伏安法对酵母核糖核酸与中性红的相互作用进行了研究。NR在玻碳电极上有一对氧化还原峰,加入yRNA后,氧化还原峰电流降低,但没有新的氧化还原峰出现,表明NR与yRNA发生了较强的相互作用,紫外光谱进一步证实该作用方式为静电作用。求得NR与yRNA的结合比为1∶2,建立了一种间接检测酵母核糖核酸的电化学方法,检测范围为5.0×10-3~0.25 g/L,检出限达1.0×10-5g/L。     

Electrochemical Study on the Interaction Betwwen Neutral Red and DNA

A voltammetric study of the interaction of neutral Red(NR) with DNA at a gold electrode in a phosphate buffer solution is described. After adding DNA in an NR solution, the reduction peak current of NR decreases. The binding mechahisms of NR to DNA in different pH ranges are different. The reduction peak potential of NR in a pH 7.0 phosphate buffer solution in the presence of DNA shifts positively, indicating that the binding of NR to DNA is intercalation action, but at pH=6.0 the reduction peak potential of NR shifts negatively, indicating that the binding of NR to DNA is electrostatic action. The formed complexes are DNA-NR when [NR]/[DNA]<0.18 and DNA-3NR when [NR]/[DNA]>0.35, respectively.     

Electrochemical Study on the Interaction Between Neutral Red and DNA

IntroductionDeoxyribonucleic acid( DNA) is the most im-portant germ plasma of most organisms.It playsan importantrole in the process ofstoring,copyingand transmitting germ messages.There have beenmany papers studying on the interaction betweensmall molecules and DNA since the1 960′s.Nowthe researches have become a field of common in-terest[1] .Those researches have contributed to theunderstanding of the way of the interaction be-tween DNA and protein.What is more,those re-searches are he…     

中性红作为DNA作用方式光谱探针的研究

以溴乙锭（ＥＢ）为探针在研究吩噻嗪药物与ＤＮＡ间相互作用的基础上,用中性红（Ｎｅｕｔｒａｌ Ｒｅｄ,ＮＲ）代替ＥＢ为ＤＮＡ作用方式对光谱探针的可行性进行了研究。结果表明,ＮＲ作为ＤＮＡ作用方式光谱探针与ＥＢ具有可比性,且由于其低毒性和高稳定性而具有较好的应用潜力。     

Thermochromism and Solvatochromism in Solution

Summary.  The thermochromic behaviour of various coordination compounds in solution is discussed, with a special focus on cyclic diamine chelates. Thermally induced spin-crossover phenomena of iron(II) complexes are also considered. The solvatochromic behaviour of mixed-ligand complexes is presented in detail. Received April 2, 2001. Accepted (revised) April 19, 2001     

Thermochromism and Solvatochromism in Solution

 The thermochromic behaviour of various coordination compounds in solution is discussed, with a special focus on cyclic diamine chelates. Thermally induced spin-crossover phenomena of iron(II) complexes are also considered. The solvatochromic behaviour of mixed-ligand complexes is presented in detail.     

Solvatochromism of thiocyanato-tetraazamacrocycle-manganese(III) complexes

Summary Solvent effects on thecharge-transfer bands of a series of thiocyanato-tetraazamacrocycle-manganese(III) complexes are reported, and discussed in terms of the donor and acceptor (hydrogen-bonding) properties of the respective solvents. The piezochromic behaviour of one of these complexes is also described.

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Solvatochromie von Thiocyanato-Tetraazamakrocyclo-Mangan(III) — Komplexen

Zusammenfassung Die Auswirkung von Lösungsmitteleffekten auf diecharge-transfer — Banden einer Reihe von Thiocyanato-Tetraazamakrocyclo-Mangan(III) — Komplexen wird im Zusammenhang mit den Donor- und Akzeptoreigenschaften des Lösungsmittels diskutiert. Das piezochrome Verhalten eines der Komplexe wird beschrieben.

     

Solvatochromism and solvation of ternary iron-diimine-cyanide complexes

Summary The solvatochromic behaviour of several complexes [Fe(LL)₂(CN)₂] with LL=Schiff base diimine has been established in a series of non-aqueous solvents, as has that of two analogues containing diazabutadiene ligands. Transfer chemical potentials have been derived from appropriate solubility measurements for several iron(II)-and iron(III)-diimine-cyanide complexes into aqueous methanol, and for [Fe(bipy)₂(CN)₂] into several binary aqueous solvent series. The usefulness of solvatochromic shifts and transfer chemical potentials as indicators of selective solvation is discussed. Kinetics of oxidation of catechol and of 4-t-butyl catechol by [Fe(bipy)(CN)₄]^– in aqueous solution are described.     

1,2,5-Triphenylpyrrole Derivatives with Dual Intense Photoluminescence in Both Solution and the Solid State: Solvatochromism and Polymorphic Luminescence Properties

Five organic luminophores, 1,2,5-triphenylpyrrole (TPP) derivatives 3 a – e bearing electron-withdrawing or electron-donating groups, have been synthesized by Pd-catalyzed Suzuki coupling of 1-phenyl-2,5-di(4′-bromophenyl)pyrrole and para-substituted phenylboronic acid derivatives. They possess good thermal stabilities with high decomposition temperatures above 310 °C. Investigation of the photophysical properties of the luminogens 3 a – e indicated that they exhibited dual intense photoluminescence in both solution and the solid state due to their twisted conformations, and their fluorescence quantum yields (Φ_F) were determined as 68.7–94.9 % in THF solution and 19.1–52.0 % in solid powder form. Compounds 3 a – c bearing electron-accepting groups exhibited remarkable solvatochromism with large Stokes shifts, attributable to their D-π-A structure and intramolecular charge-transfer effect. In particular, 3 a , bearing aldehyde groups, displayed an obvious red-shift of the emission band from 445 to 564 nm with increasing solvent polarity. However, no obvious solvatochromic behavior was observed for compounds 3 d , e bearing electron-donating groups. The luminophore 3 a exhibited polymorphic luminescence properties and crystallization-induced emission enhancement.     

Molecular Spectroscopic Study on the Interaction between Heparin and Neutral Red

The interaction between heparin and neutral red was investigated by molecular spectroscopic methods. The change of all spectra suggested that positively charged neutral red had interacted with negatively charged heparin. The study of influence factors indicated that electrostatic force and hydrophobic bond might be involved in the interaction. The total binding number per disaccharide unit and intrinsic binding constant were obtained using Scatchard model.