菁染料J-聚集体的微观结构研究

用原子力显微镜观察了阴阳离子菁染料及对应的阴离子菁染料和阳离子菁染料吸附在立方体(100)和八面体(111)溴碘化银乳剂颗粒表面形成的J-聚集体的微观结构,得到了3种不同排列的J-聚集体结构。研究结果表明,菁染料分子在溴碘化银颗粒表面不是单层吸附,而是以一定的形状聚集在溴碘化银表面。阴阳离子菁染料形成的J-聚集体为"鱼骨"状;阴离子菁染料的J-聚集体以"卡片堆积"式排列;阳离子菁染料J-聚集体为"磁砖"式结构。     

混合菁染料J-聚集体的光谱性能研究

对2种混合菁染料吸附在溴化银颗粒表面形成的J-聚集体的反射光谱及感光性能与对应菁染料单独吸附在溴化银颗粒表面进行了对比研究。用紫外-可见分光光计测定了菁染料吸附在溴化银颗粒表面形成J-聚集体的反射光谱。结果表明:2种混合菁染料吸附在溴化银颗粒表面形成的J-聚集体的反射光谱分别具有2个最大峰值波长,并且与对应菁染料单独使用时的峰值波长相一致。2种混和菁染料的感光性能比对应菁染料单独使用时有较大提高。     

感绿菁染料J-聚集体吸附在氯化银微晶表面的吸收光谱

染料J-聚集体对于现代彩色信息记录与存储材料、生物光电子器件、光合作用、太阳能转换与存储等方面具有十分重要的应用前景和理论意义。感绿菁染料在适当浓度时,对立方体氯化银微晶有增感效应,文章应用吸收光谱法对增感后的氯化银微晶样品进行了研究。研究表明, 增感染料浓度低于0.02 mL(染料浓度为5.0 mg·mL-1)/40 g乳剂时,感绿菁染料在立方体氯化银表面不形成J-聚集体,吸收光谱没有J-聚集体吸收峰出现;当染料浓度高于0.2 mL(染料浓度为5.0 mg·mL-1)/40 g乳剂时,染料开始在立方体氯化银微晶表面聚集并形成J-聚集体,吸收光谱有J-聚集体吸收峰出现。随染料浓度进一步增加,J-聚集体的吸收明显加强,吸收峰有微小的红移。     

表面增强能量转移效应的研究

通过分析2、2′菁染料水溶液、银胶体以及2、2′菁染料吸附于银胶表面时的吸收光谱得知,2、2′菁染料吸附于银胶表面时,有J聚集体出现,通过分析基频及高阶线性Raman光谱,证实了一些低波数的Raman信号是由J聚集体产生的,从而进一步证实了吸附于银胶表面的2、2′菁染料以单体和J聚集体形式共存.同时,由吸收光谱还可以看出,2、2′菁染料分子及其J聚集体分子的吸收带都处于银胶吸收带的半高宽范围内,满足共振条件,当用不同激发波长(514.5 nm和488 nm)的光激发吸附于银胶表面的2、2′菁染料时,观察到了J聚集体的敏化荧光,而用此激发光激发2、2′菁染料水溶液时,就没有观察到J聚集体的敏化荧光,从而说明了银胶表面的存在,加速了单体2、2′菁染料分子与其J聚集体分子之间的能量转移速率.     

阴阳离子菁染料J-聚集体的荧光光谱研究

采用荧光光谱技术,研究了两种阴阳离子菁染料及对应的阴离子和阳离子菁染料在溴碘化银立方体颗粒上形成的J-聚集体的荧光光谱特性,并与其在溴碘化银立方体上的光谱增感率进行了实验对比。结果表明：阴阳离子菁染料的荧光光谱峰值明显低于阴离子、阳离子菁染料,说明其吸收光子后,大部分电子转移到溴碘化银表面。因此具有较高的光谱增感效率。     

取代萘酞菁化合物LB膜的光谱特性研究

研究了四叔丁基萘酞菁和四叔丁基萘酞菁锌两种对称取代萘酞菁化合物LB膜的制备及其它们的聚集特性。两种萘酞菁化合物均能制成很好的LB膜。在稀溶液中，四叔丁基萘酞菁以单体为主要存在形式；而四叔丁基萘酞菁锌不仅能形成H-聚集体，而且还能形成J-聚集体，且主要以聚集体的形式存在。在LB膜中，两种化合物均形成了H-聚集体。     

中心对称萘酞菁分子的LB膜及其聚集特性研究

研究了三种中心对称的萘酞菁分子LB膜的制备及其聚集特性。三种萘酞菁化合物均能制成很好的LB膜。在稀溶液中,四叔丁基萘酞菁以单体为主要存在形式;对四叔丁基萘酞菁锌,由于金属锌原子的作用,在稀溶液中不仅能形成H-聚集体,而且还能形成J-聚集体,且主要以聚集体的形式存在。在LB膜中,这两种化合物均形成了H-聚集体。对于双四叔丁基萘酞菁铒不论在稀溶液中还是在LB膜中均主要以单体的形式存在。     

阴阳离子菁染料在溴碘化银乳剂颗粒上J-聚体反射光谱

本文对两种阴阳离子菁染料在碘溴化银立方体颗粒表面的聚集行为进行了研究。用紫外-可见分光光度计测定了菁染料J-聚集的反射光谱曲线。与对应的阴离子、阳离子菁染料各自在碘溴化银立方体颗粒表面的聚集进行了实验对比。结果表明:阴阳离子菁染料吸附在碘溴化银立方体颗料表面形成的J-聚集态的反射光谱具有单个阴离子、阳离子菁染料形成J-聚体反射光谱的峰值波长。表明阴阳离子菁染料具有两个感色区域,既有阴离子菁染料的感色区又有阳离子菁染料的感色区。     

取代基对双酞菁铥LB膜及光谱特性的影响

采用紫外-可见吸收光谱的方法研究了三种稀土夹心双酞菁铥化合物在溶液和LB膜中的聚集性和光谱特性。实验结果表明三种稀土双酞菁化合物在氯仿溶液中形成了H-聚集体,但当浓度比较低时,溶液中表现出单体的吸收。取代基OC₈H₁₇的加入使氯仿溶液中双酞菁铥化合物的聚集性减弱,而且使得吸收峰发生红移,对吸收峰的强度也有较大的影响,造成了Soret吸收带的分裂。另外,取代基OC₈H₁₇对LB膜中双酞菁分子的存在状态有较大的影响,在LB膜中,TmPc₂和TmPcPc*分子以H-聚集体的形式存在,而TmPc*₂分子以T-聚集体的形式存在。形成LB膜后,由于双酞菁分子之间排列紧密,相互作用加强,使得薄膜中分子聚集体的吸收峰相对于溶液中聚集体的吸收峰发生了一定的红移,薄膜中分子排列方向的不同对吸收光谱也有一定的影响。     

新型菁类染料聚集体构筑和它的非线性光学特性研究

采用旋涂法制备了一种五甲川菁染料的超薄膜,利用原子力显微,椭偏仪、UV-Vis吸收光谱、红外光谱、小角X射线衍射等对薄膜的形貌和线性光谱性质进行了研究表征,结果表明染料在薄膜中形成了有序而稳定的J-聚集体,前向简并四波混频(DFWM)技术研究表明由于分子的聚集作用引起三阶非线性极化率的增大(χ(3)=2.55×10-12esu),利用激子耦合模型初步分析和讨论了产生非线性效应增强的内在机制。     

Novel,Monomeric Cyanine Dyes as Reporters for DNA Helicase Activity

The dimeric cyanine dyes, YOYO-1 and TOTO-1, are widely used as DNA probes because of their excellent fluorescent properties. They have a higher fluorescence quantum yield than ethidium homodimer, DAPI and Hoechst dyes and bind to double-stranded DNA with high affinity. However, these dyes are limited by heterogeneous staining at high dye loading, photocleavage of DNA under extended illumination, nicking of DNA, and inhibition of the activity of DNA binding enzymes. To overcome these limitations, seven novel cyanine dyes (Cyan-2, DC-21, DM, DM-1, DMB-2OH, SH-0367, SH1015-OH) were synthesized and tested for fluorescence emission, resistance to displacement by Mg²⁺, and the ability to function as reporters for DNA unwinding. Results show that Cyan-2, DM-1, SH-0367 and SH1015-OH formed highly fluorescent complexes with dsDNA. Of these, only Cyan-2 and DM-1 exhibited a large fluorescence enhancement in buffers, and were resistant to displacement by Mg²⁺. The potential of these two dyes to function as reporter molecules was evaluated using continuous fluorescence, DNA helicase assays. The rate of DNA unwinding was not significantly affected by either of these two dyes. Therefore, Cyan-2 and DM-1 form the basis for the synthesis of novel cyanine dyes with the potential to overcome the limitations of YOYO-1 and TOTO-1.     

Fluorescent Properties of Pentamethine Cyanine Dyes with Cyclopentene and Cyclohexene Group in Presence of Biological Molecules

A series of pentamethine cyanine dyes with cyclohexene or cyclopentene group in polymethyne chain, assumed as DNA groove-binders, were studied as fluorescent probes for nucleic acids as well as for native and denatured proteins. It was revealed that the presence of methyl or dimethyl substituent in 5 position of the cyclohexene group hinders the formation of dye–DNA fluorescent complex, while the methyl substituent in 2 position leads to the increasing of the dye–DNA complex fluorescence intensity. The dyes SL-251, SL-1041, and SL-1046 containing methyl group in the 2 position of the cyclic group, are reported as bright DNA-sensitive dyes. The study of the dyes DNA-binding specificity demonstrated significant AT-preference that points to the groove-binding interaction mode. At the same time, the dyes SL-251, SL-377, and SL-957 with the 2-methyl substituted cyclohexene group were shown to be sensitive fluorescent dyes both for nonspecific (in SDS presence) proteins detection and for native BSA.     

pH-Sensitive Cyanine Dyes for Biological Applications

A series of functionalized, water-soluble, pH-sensitive pentamethine cyanine (Cy^TM5) dyes has been designed and synthesized. These probes are fluorescent in acidic media but are non-fluorescent in an alkaline environment. Subtle changes to the structure of these probes can lead to pronounced changes in the pKa of these probes. These probes have been utilized in a cellular environment to detect localized changes in pH using the IN Cell Analyzer, a confocal imager formatted for imaging of cell-based assays.     

The Influence of the Molecular Structure of Cyanine Dye on the Component Composition of Molecular Layers

The formation of the component composition of symmetric cationic cyanine dyes on glass is studied. The absorption spectra of layers of three homologous series of dyes with end heterocyclic groups of different spatial and chemical compositions are measured, and the absorption spectra of monomer components and aggregates are separated. The component compositions of layers of different thicknesses are compared. It is shown that the widening of the absorption spectra of molecular layers against the spectra of ethanol solutions of these compounds is caused mainly by the formation of various monomer stereoisomers and molecular aggregates and their interaction with the substrate surface and the neighborhood. The number of isomer forms and their relative concentrations depend on the layer thickness, the electron donor ability and spatial structure of end groups, and the cation conjugation chain length. The influence of the anion manifests itself only in the concentration ratio of the formed monomers and a small shift of the maxima of their absorption bands. The increase in the number of monomer forms produced in the layer corresponds to the increase in the conjugation chain length. Spatial obstacles created by heterocyclic groups inhibit the formation of definite stereoisomers, which reduces the number of components of the layer.     

Kinetics study of ultrafast electron transfer from sensitized dyes to silver halide microcrystals

Spectral sensitization micromechanism of cyanine dyes J-aggregate adsorbed on the tabular and cubic AgBr microcrystals with different dye concentrations is studied by using picosecond time-resolved fluorescence spectroscopy, and the dependences of electron transfer and spectral efficiency sensitization on different conditions are analysed in detail. With the steady spectroscopy, the wavelengths of absorption and fluorescence of J-aggregate adsorbed on AgBr microcrystals are found to shift to red relative to dye monomer. The spectrum of fluorescence has a red shift relative to the absorption peak. With the time-resolved fluorescence spectroscopy, the fluorescence decay curves of cyanine dyes J-aggregate adsorbed on the tabular and cubic AgBr grains are found to be fitted well by a double-exponential decay function. The fitting curves consist of a fast and a slow component. Because of the large amplitude of the fast component, this fast decay should be attributable mainly to the electron transfer from J-aggregate of dye to a conduction band of AgBr.     

A New Fluorescence Resonance Energy Transfer Pair and Its Application to Oligonucleotide Labeling and Fluorescence Resonance Energy Transfer Hybridization Studies

We describe two new fluorescence resonance energy transfer (FRET) compatible labels, their covalent linkage to oligonucleotides, and their use as donor and acceptor, respectively, in FRET hybridization studies. The dyes belong to the cyanine dyes, and water solubility is imparted by a phosphonate which represents a new solubilizing group in DNA labels. They were linked to amino-modified synthetic oligonucleotides via oxysuccinimide (OSI) esters. The studies performed include binding assays, determinations of molecular distances, homogeneous competitive assays, and limits of detection, which are in the order of 5 pmol/L for a 15-mer.