Highly Efficient Photosensitization of Mesoporous TiO_2 Electrode with a Cyanine Dye

A low cost cyanine dye, 1,1-dimethyl-3-ethyl-2-[3-(1,3-dihydro-3,3-dimethyl-1-ethyl- 5-carboxyl-2H-indol-2-ylidene)-1-propenyl]-1H-benz[e] indolium iodide (1) was synthesized and applied to sensitize mesoporous TiO2 electrode. Photoresponse of the electrode was extended to the visible and remarkably high incident photon-to-current conversion efficiency (IPCE) over 70% was achieved from 500 nm to 600 nm.

DFT Investigation on the Trans-cis Photoisomerization of Pentamethine Cyanine Dye Model Molecule

The trans-cis photoisomerization of pentamethine cyanine dye （Cy5） has been theoretically investigated by the analysis on an analogical molecule model. All possible isomers have been searched by rotating the different bridge C-C bonds of the model. The relative stability of the isomers for the ground and first excited states as well as the corresponding excitation mechanism has been envisaged by DFT and time-dependent DFT method. The results show different conjugation degree of the isomers resulting in different absorption energy upon the different C-C bridge bond rotation. From the analyses of electronic density distribution of the frontier orbitals, it is predicted that there is charge transfer besides the π-π^＊ excitation for the cyanine dye model, which makes the mechanism and photo-properties different form those of other conjugated molecules.

Synthesis and Characterization of a Squarylium Cyanine Dye with Two [60]Fullerene Units

A new [60]fullerene dimer 2 in which two C-60 units are covalently attached to a squarylium cyanine dye has been synthesized and characterized.

STUDIES ON CROWN ETHER CYANINE DYES (X). THE SYNTHESIS OF BENZOXAZOLE CROWN ETHER CYANINE DYES

A simple method for synthesis of benoxazole crown ether cyanine dyes is described.

STUDIES ON CROWN ETHER CYANINE DYES(XI)THE SYNTHESIS OF BENZOTELLURAZOLE CROWN ETHER CYANINE DYES

Three methods for synthesis of benzotellurazole crown ether(6)are described.The cyanine dye(8)can be easily obtained by treating(6) with CH_3I and CH(OEt)_3.

Synthesis and Photophysical Properties of Novel Highly Stable Zero/Bis-Zero Methine Cyanine Dyes Based on N-Bridgehead Heterocycles

Cyanine dyes of zero/bis-zero methine incorporating imid-azo(1,2-a)Pyridine (quinoline) or pyrazino(1,2-a)pyridine (quinoline) with stable C-N bond were synthesized using keto-oxime methylene C-link heterocyclic quaternary salts [1-phenyl-3-methyl-pyrazolino-4-keto-oxime-α-methylene-bis-pyridin-(quinoin)-1(4)-di-ium-iodide(ethiodide) salts and 1-phenyl-3-methyl-pyrazolino- 4-ketooxime-α-methylene-N-2-methyl-bis pyridin (quinoin)-1(4)-di-ium-iodide(ethiodide) salts]. Such heterocyclic precursors and related dyes were identified by elemental and spectral analyses. The absorption spectra properties of such dyes were investigated in 95% Ethanol to attempt and throw some light on the influence of such new heterocyclic nuclei and to compare or evaluate spectral behaviors. The absorption spectra of dyes in different pure solvents were examined in the visible region showing solvatochromism and the colour changes of dyes with solvents having different polarities. This permits a selection of the optimal solvent (fractional solvent) when such dyes are applied as photosensitizers. The spectral behavior of some selected newly synthesized cyanine dyes is observed in mixed solvents of different polarities and progressively increasing quantities of one solvent over the other were studied and showed an increase in the absorbance of CT band with increasing proportion of that solvent. Evidence for hydrogen bond formation between the solute molecules and solvent molecules allows measurement of certain energies such as hydrogen bonding, orientation, and free energies.

Theoretical and Experimental Study of the Mechanism of Reaction Formation of Cyanine Dyes

To study the theoretical bases of the mechanism of reaction formation of cyanine dyes, special importance is gained by methods of quantum chemistry. The use of these methods is provided with the known molecular and dynamic HyperChem program. The purpose of studying was quantum and chemical studying of features of a geometrical and electronic structure of model molecules of penicillin acid, of derivative of glutaconic dialdehyde (DGD), and the cyanine dyes, and also an assessment of power of process of their formation. For studying was carried out the experimental mark of chemism of course of reaction with theoretical justification of the mechanism of reaction formation of cyanine dyes. The results show that all studied model molecules are thermodynamic steady systems to what values of enthalpies of their formation, rather high on an absolute value, testify negative on a sign. Reaction goes by the mechanism of nucleophilic addition.

Unusual Spectral Change Due to a Cyanine Dye Adsorbed on an Inorganic Layered Material upon Photoirradiation

Photoinduced spectral change can be utilized for various optical devices. The photoinduced spectral change due to an organic dye was demonstrated for the organic-inorganic hybrid film without the aid of photochromism with a simple preparation method for the first time. By the hybridization of a cyanine dye of 2-[5-(1,3-dihydro-3,3-dimethyl-1-octadecyl-2H-indol-2-ylidene)-1,3-pentadienyl]-3,3-dimethyl-1-octadecyl-3H-indolium perchlorate (NK3175) with an inorganic layered material of cation-exchangeable clay, smectite (SWN), a spectral change attributed to NK3175 was generated upon the irradiation of UV light. This result might serve as useful information on the methodology to produce optically controlled function for photoresponsive systems. Furthermore, the hybrid film of SWN and NK3175 was characterized by the use of XRD and FT-IR measurements. NK3175 molecules adsorbed onto external surfaces of SWN were confined by oriented SWN. It was suggested that the enhanced intermolecular interaction between NK3175 molecules caused by the hybridization with SWN resulted in the change of the aggregation state of NK3175 upon the UV light irradiation, which accounts for the spectral change of NK3175.

Study on the Direct Photooxidation of Near-Infrared Absorbing Benzothiazolone Cyanine Dye

In this paper, direct photooxidation of benzothiazolone cyanine dye: in acetonitrile was studied. The photoproducts had been identified by (HNMR)-H-1 and fast atom bombardment (FAB) mass spectrometry. The results showed that the N-ethylbenzothiazolone (I), the ionic acid (II), and ionic aldehyde (III) are the principal photoproducts.

Squarylium Cyanine Dyes for Photoelectric Conversion

Two squarylium cyanine dyes (Sqs) were synthesized to explore their applications in photoelectrochemical solar cells. Nanocrystalline TiO2 electrodes modified with Sqs have been prepared to probe the photosensitization effects. A rather high photoelectric conversion efficiency of up to 2.17% and the top incident monochromatic photon-to-photocurrent conversion efficiency (IPCE) of 6.2% at 650nm were obtained from the Sq2-modified nanocrystalline TiO2 electrode.

Anisotropy in Third-Order Nonlinear Optical Susceptibility of a Squarylium Dye in a Nematic Liquid Crystal

A squarylium dye is dissolved in 4-cyano-4＇-pentylbiphenyl （SCB） and oriented by sandwiching mixtures between two pieces of rubbed glass plates. The optical absorption spectra of the oriented squarylium dye-5CB layers exhibit high anisotropy. The third-order nonlinear optical responses and susceptibilities X^（3）e of squarylium dye in 5CB are measured with light polarizations parallel and perpendicular to the orientational direction by the resonant femtosecond degenerate four-wave mixing （DFWM） technique. Temporal profiles of the DFWM signal of the oriented squarylium dye-5CB layers with light polarizations parallel and perpendicular to the orientational direction are measured with a time resolution of 0.3ps （FWHM）, and are found to consist of two components, i.e., the coherent instantaneous nonlinear response and slow response due to the formation of excited molecules. A high anisotropic ratio of x^（3）e, 10.8 ：k 1.2, is observed for the oriented layers.

HSA shrinkage optimizes the photostability of embedded dyes fundamentally to amplify their efficiency as photothermal materials

Focused on the performance promotion of organic small molecular dyes based photothermal agents via non-chemical modification,we found that heat-assisted binding of human serum albumin(HSA)to the dye causes shrinkage of the protein and encapsulate the dye to form nanoparticles.This revolutionizes the photostability of small molecule dyes which further improves their photothermal conversion effi-ciency and tumor ablation performance as photothermal agents significantly.In this work,the obtained photothermal agent named HSA-P2-T could accumulate in tumor and induce 22℃enhancement of the tumor in xenograft models upon ultra-low dose(0.1 W/cm^(2))laser irradiation,which,as far as we know,is the lowest laser dose used in vivo photothermal therapy.Utilizing HSA-P2-T,we realized tumor ablation upon twice intravenous injections of the nanoparticles and four photothermal treatments.

Single molecule fluorescence fluctuations of the cyanine dyes linked covalently to DNA

The intersystem crossing and isomerization dynamics of free-Cy3,Cy3-ssDNA,free-Cy5 and Cy5-ssDNA are obtained through simple analysis of rapid on/off blinking from single molecule fluorescence intensity time-traces and the fluorescence correlation spectroscopy(FCS).The on-and off-times observed in fluorescence time traces of single cyanine dyes are due to the formation of the triplet state and isomerization,where both the interaction with DNA and long central polymethine chain of cyanine dyes increase the barriers of isomerization,leading to long off-time.The results indicate that the single molecule fluorescence fluctuation together with the resulting second autocorrelation analysis are powerful methods for determining the triplet state and isomerization dynamics,which could be the simple techniques and complementary to other spectroscopic techniques,such as fluorescence decay measurement and laser flash photolysis to study the photophysical processes of complex molecules.

Investigation of a cyanine dye assay for the evaluation of the biocompatibility of magnesium alloys by direct and indirect methods

Magnesium and its alloys are promising candidates for a new generation of biodegradable metals in orthopaedic applications due to their excellent biocompatibility,biodegradability,and mechanical properties that are similar to natural bone.However,direct in vitro assessment of these materials in the presence of cells is complicated by degradation products from the alloy that lead to a false positive for the most commonly used cell adhesion and cell proliferation assays.In this paper,a cyanine dye was used to quantitatively evaluate the in vitro biocompatibility of a Mg AZ31 alloy by both direct and indirect methods.The cytotoxicity of the corrosion products was evaluated via an indirect method;a 25%decrease in cell viability compared to control samples was observed.Moreover,direct assessment of cell adhesion and proliferation showed a statistically significant increase in cell number at the surface after 72 h.In addition,the degradation rate and surface characteristics of the Mg AZ31 alloy were evaluated for both direct and indirect tests.The degradation rate was unaffected by the presence of cells while evidence of an increase in calcium phosphate deposition on the magnesium alloy surface in the presence of cells was observed.This study demonstrates that a cyanine dye based assay provides a more accurate assessment of the overall in vitro biocompatibility of biodegradable metals than the more commonly used assays reported in the literature to date.

一种基于类花菁检测过氧化氢荧光探针的合成

文章以2-甲基苯并噻唑和尼泊金乙酯为原料,合成了一种具有红色荧光的花菁类染料,该染料与4-溴甲基苯硼酸频哪醇酯反应可以生成用于检测过氧化氢的荧光探针。通过紫外和荧光研究该探针在不同溶剂、过氧化氢浓度、黏度条件下检测过氧化氢的响应。研究结果表明。在该实验中,过氧化氢浓度越高、体系黏度越低,探针荧光强度均逐渐降低,同时具有良好的选择性。

花菁树枝状大分子的合成与性质研究

花菁染料因具有高荧光产率、高摩尔消光系数、狭窄的吸收/发射波段等优点,而被广泛用于荧光诊疗领域。但在实际应用中,存在稳定性差、易淬灭和光漂白等问题,而纳米技术可以克服这些弊端。采用发散合成法制备了一系列以七甲川花菁染料为核心分子、以生物相容性优异的赖氨酸为分支单元的荧光树枝状大分子。对其进行了结构和光学性能的表征,并初步探究了该荧光树枝状大分子在体外细胞中的成像能力。结果表明:合成得到的第一到第三代花菁树枝状大分子具有精准的化学结构,纯度较高,荧光强度、荧光量子产率及荧光寿命均随着代数的增加而增长,并显示出良好的细胞荧光成像的能力。

利用功能性DNA结构对重金属铅离子进行快速检测

重金属铅离子是具有较大毒性并且属于严重破坏环境的污染物,铅离子的快速检测受到了人们的广泛关注。采用功能性DNA和菁染料ETC的特异性识别构建铅离子探针,达到快速响应检测铅离子含量的目的。菁染料ETC能够特异性识别平行构型G-四链体,在吸收光谱上表现出单体特征吸收峰,铅离子能够将平行构型G-四链体逐渐诱导形成反平行G-四链体,从而引起ETC的聚集体变化,根据特征吸收峰值的变化来检测铅离子含量。

一种基于DNA G-四链体结构的汞离子快速检测方法

随着工业的发展汞污染日渐严重,建立一种快速、准确的Hg^(2+)检测手段变得更加重要。某些富鸟嘌呤(G)的核酸序列能够通过氢键和自身链或者其他序列链上的鸟嘌呤(G)连接折叠成为四链结构,称为G-四链体。Hg^(2+)可以和G-四链体中的胸腺嘧啶T相互作用形成T-Hg^(2+)-T结构,G-四链体也会形成DNA双链结构,这种变化可以影响菁染料的聚集状态,进而引起溶液紫外-可见吸收光谱的变化。基于DNA G-四链体转化菁染料聚集状态开发了一种Hg^(2+)检测手段。

Structure of Cyanine Dye Aggregates Observed by Scanning Tunneling Microscopy

In solution and on a variety of substrates, the ability of spectral sensitizing dyes to form molecular aggregates with close intermolecular spacings and strong coupling is a well-known phenomenon. A given dye may form several different types of aggregates, which exhibits spectral shifts of±100 nm from the monomer spectrum in the solution. Aggregate of dye ab-

Phase Transition of Cyanine Dye Monolayer on the Air/Water Surface Observed Under Brewster Angle Microscope

It is an extensively used method recently to prepare the mixed monolayer of cyanine dye by spreading a mixed solution of short chain cyanine dye and long chain fatty acid on a water surface. The method is very important for the molecular architecture because it makes non-amphiphilic molecules form monolayer on water surface. But the molecular arrangement of this kind of mixed monolayer is unclear under different surface pressures.