Intermolecular interaction between squarylium cyanine and porphyrin

In this paper, the interaction between squarylium cyanine and porphyrin in chloroform is investigated by absorption and fluorescence spectroscopy. Emphasis has been put on the mechanism of intermolecular energy transfer. The overlap integral J between the absorption spectrum of squarylium cyanine and the fluorescence spectrum of porphyrin was calculated, which reveals that the singlet-singlet energy transfer may occur from porphyrin to squarylium cyanine in solution. In comparison of the observed rate constant [kqII=6.1 ×1013 (mol/L)-1·s-1] for fluorescence quenching of porphyrin by squarylium cyanine with the diffusion rate constant in chloroform [kdif=1.1×1010 (mol/L)-1·s-1] and the rate of energy transfer [ket≤6.7×104 (mol/L)-1·s-1 in the experimentally dilute solutions] estimated from Forster formula, the possibility of energy transfer by electron exchange or/and coulombic mechanism could be excluded. So it has been definitely convinced that the intermolecuiar energy transfer between them is     

Water-soluble cyanine dyes for biological microchip technology

Novel indodicarbocyanine dyes were obtained and their spectroscopic characteristics were determined. For equal concentrations of the dyes, the relative fluorescence efficiency was measured at the excitation wavelengths λ = 635 and 655 nm and the emission wavelengths λ = 670 and 690 nm, respectively. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2355–2359, December, 2007.     

方酸菁染料的合成

方酸菁染料业经证明具有光谱增感作用,但迄今未见其作为照相材料应用的报道.1973年法国Siegfried等将其用于巨脉冲红宝石激光的无源切换;最近Morel等又研究了它们在太阳能电池中的应用.作者合成了八个方酸菁染料,并对它们的照相性能和光电转换特性作了初步研究;发现其中的个别化合物不但具有良好的光谱增感作用,而且与照相工业中常用的染料“1833”相比,衰退也比较慢;部分化合物还表现出相当高的光电转换效率. 作者曾报道方酸的合成.本文介绍另一种方法,即以醋酸钠-醋酸环化1,1,3-三氯-2,     

Singlet oxygen generation in PUVA therapy studied using electronic structure calculations

The ability of furocoumarins to participate in the PUVA (Psoralen + UV-A) therapy against skin disorders and some types of cancer, is analyzed on quantum chemical grounds. The efficiency of the process relies on its capability to populate its lowest triplet excited state, and then either form adducts with thymine which interfere DNA replication or transfer its energy, generating singlet molecular oxygen damaging the cell membrane in photoactivated tissues. By determining the spin–orbit couplings, shown to be the key property, in the intersystem crossing yielding the triplet state of the furocoumarin, the electronic couplings in the triplet–triplet energy transfer process producing the singlet oxygen, and the reaction rates and lifetimes, the efficiency in the phototherapeutic action of the furocoumarin family is predicted as: khellin < 5-methoxypsoralen (5-MOP) < 8-methoxypsoralen (8-MOP) < psoralen < 4,5′,8-trimethylpsoralen (TMP) < 3-carbethoxypsoralen (3-CPS), the latter being the most efficient photosensitizer and singlet oxygen generator.     

Tuning the photoinduced electron transfer in near-infrared heptamethine cyanine dyes

An efficient photoinduced electron transfer (PET) system in near-infrared region was described. The PET in heptamethine cyanine dyes was tuned by changing the electron-donating ability of the substituent at the central position of the polymehine chain. 4-Aminophenylthio-substitution led to an efficient PET and the lowest fluorescence quantum yield. The acetylation, protonation or transition metal cation coordination of the amino group could recover fluorescence greatly via suppressing the PET.     

Protein labeling with red squarylium dyes for analysis by capillary electrophoresis with laser-induced fluorescence detection

Two new red luminescent asymmetric squarylium dyes (designated "Red-1c and Red-3") have been shown to exhibit absorbance shifts to longer wavelengths upon the addition of protein, along with a concomitant increase in fluorescence emission. Specifically, the absorbance maxima for Red-1c and Red-3 dyes are 607 and 622 nm, respectively, in the absence of HSA, and 642 and 640 nm in the presence of HSA, making the excitation of their protein complexes feasible with inexpensive and robust diode lasers. Fluorescence emission maxima, in the presence of HSA, are 656 and 644 nm for Red-1c and Red-3, respectively. Because of the inherently low fluorescence of the dyes in their free state, Red-1c and Red-3 were used as on-column labels (that is, with the dye incorporated into the separation buffer), thus eliminating the need for sample derivatization prior to injection and separation. A comparison of precolumn and on-column labeling of proteins with these squarylium dyes revealed higher efficiencies and greater sensitivities for on-column labeling, which, when conducted with a basic, high-salt content buffer, permitted baseline resolution of a mixture of five model proteins. LOD for model proteins, such as transferrin, alpha-lactalbumin, BSA, and beta-lactoglobulin A and B, labeled with these dyes and analyzed by CE with LIF detection (CE-LIF) were found to be dependent upon dye concentration and solution pH, and are as low as 5 nM for BSA. Satisfactory linear relationships between peak height (or peak area) and protein concentration were obtained by CE-LIF for this on-column labeling method with Red-3 and Red-1c.     

New unsymmetrical cyanine dyes for real-time thermal cycling

Asymmetric cyanine dyes bind to the minor groove of double stranded DNA (dsDNA) owing to their crescent configuration; therefore, these dyes are widely used as a dsDNA probes. BOXTO-MEE is derived from BOXTO by adding the polar methoxyethoxyethyl tail in order to increase solubility, dissociation rate kinetics, and stability. As a result, BOXTO-MEE showed significant reduction in nonspecific amplification (primer dimers) without significant effect on target sequence amplification, PCR efficiency, and standard curve correlation coefficient. BETIBO is another example of an asymmetric cyanine dye that can binds to dsDNA but is less efficient than BOXTO-MEE for use in real-time PCR. Statistical analysis of reproducibility results shows that BETIBO is not strong enough to be used for quantifying low nucleic acid quantities. Statistical analysis for BOXTO-MEE results shows that there is no significant difference between the efficiency and correlation coefficient achieved by BOXTO-MEE and SYBR Green I, but a significant difference in the dynamic range is observed because BOXTO-MEE has a wider dynamic range. BOXTO-MEE stock solution was stable at −20 °C for more than 1 year and 40 μM solution was stable for 45 days (at least) at 4 °C.     

Synthesis and spectral properties of cyanine dyes based on indeno[2,1-<Emphasis Type="Italic">b</Emphasis>]chromene

Starting from the products of formylation and vinylformylation of indeno[2,1-b]chromene a series of new symmetrical and unsymmetrical polymethine dyes have been synthesized with a residue of indeno[2,1-b]chromene as the terminal group. It was shown that the unsymmetrical dyes obtained have two absorption bands in the visible region, the position, intensity, and shape of which depend on the nature of the second terminal group.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 92–99, January, 2005.     

An efficient approach to the synthesis of water-soluble cyanine dyes using poly(ethylene glycol) as a soluble support

An efficient synthesis approach to unsymmetrical water-soluble cyanine dyes has been established. Loading and activation of sulfoindolenium to poly(ethylene glycol) (PEG) have been achieved via a simple strategy. Cyanine dyes are released by the attack of heterocyclic carbon nucleophile and the cleavage of PEG-bound hemicyanine. The efficient approach delivers cyanine dyes in high purity without the nontrivial chromatographic separation.     

Synthesis of PEG derivatives bearing aminophenyl and their application for liquid-phase synthesis of water-soluble unsymmetrical cyanine dyes

The synthesis and NMR characterization of soluble PEG-supported polymers were described, and their subsequent application for liquid-phase synthesis of water-soluble cyanine dyes was also studied. Nucleophilic substitution of tosylation of PEG 16 with 1,3-bis(4-nitrophenoxy)-2-propanol 15 under basic conditions, followed by nitro group reduction, gave PEG-bound aminophenyl 18. Another PEG-bound aminophenyl 28 was prepared by condensation reaction of PEG-bound pentaerythritol 25 and 4-aminobenzoic acid followed by the cleavage of BOC group. Subsequent loading and activation of sulfoindoleninium to PEG derivatives 18 or 28 were achieved via simple strategies. Cyanine dyes were released by the attack of heterocyclic carbon nucleophile and the cleavage of PEG-bound hemicyanine without the chromatographic separation. The efficient, facile, and practical approaches appear to be robust and versatile strategies to deliver not only indocyanine dyes but also benzoindocyanine dyes.     

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. Supported by the National Natural Science Foundation of China (Grant Nos. 20773139, 20833008 & 20825314), and State Key Project for Fundamental Research (Grant Nos. 2006CB806000 & 2007CB815200)     

Synthesis and photophysical evaluations of β-fused uracil-porphyrin derivatives

New β-fused uracil-porphyrin conjugates were synthesized by the tetramerization of uracil-pyrroles under acidic conditions. Two different synthetic approaches were systematically studied in order to evaluate their efficiency, as well as the possibility to obtain a single regioisomer. Metallation effects were studied for aggregation in solution, and preliminary photophysical experiments were also performed in order to evaluate the potential of these new compounds.     

冠醚苯并恶唑菁染料的合成

本文报道含冠迷苯并恶唑菁染料及半菁染料的合成,采用一种简便方法合成了关健中间体2-甲基6,7-二羟基苯并恶唑:从2,3,4-三羟基苯乙酮肟经beckmann重排而得到,将它再与三甘醇或四甘醇二氯化物反应 ,分别得到相应的冠醚化合物:2-甲基-6,7-并(12-冠-4)苯并恶唑和2-甲基-6,7-并(15-冠-5)苯并恶唑,将它们制成相应的季铵盐 ,然后分别与原甲酸乙酯或对二甲胺基甲醛作用,得到相应的冠醚恶唑菁染料,或半菁染料.     

Derivatization of a rigid meso-substituted heptamethine cyanine dye

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Ag_7(MBISA)_6 Nanoclusters Conjugated with Quinacrine for FRETEnhanced Photodynamic Activity under Visible Light Irradiation

Singlet oxygen(1 O2) plays an important role in various applications, such as in the photodynamic therapy(PDT) of cancers,photodynamic inactivation of microorganisms, photo-degradation of toxic compounds, and photo-oxidation in synthetic chemistry. Recently,water-soluble metal nanoclusters(NCs) have been utilized as photosensitizers for the generation of highly reactive 1 O2 because of their high water solubility, low toxicity, and surface functionalizability for targeted substances. In the case of metal NC-based photosensitizers, the photo-physical properties depend on the core size of the NCs and the core/ligand interfacial structures. A wide range of atomically precise gold NCs have been reported; however, reports on the synthesis of atomically precise silver NCs are limited due to the high reactivity and low photostability(i.e., easy oxidation) of Ag NCs. In addition, there have been few reports on what kinds of metal NCs can generate large amounts of 1 O2. In this study, we developed a new one-pot synthesis method of water-soluble Ag7(MBISA)6(MBISA= 2-mercapto-5-benzimidazolesulfonic acid sodium salt) NCs with highly efficient 1 O2 generation ability under the irradiation of white light emitting diodes(LEDs). The molecular formula and purity were determined by electrospray ionization mass spectrometry and gel electrophoresis. To the best of our knowledge, this is the first report on atomically precise thiolate silver clusters(Agn(SR)m) for efficient 1 O2 generation under visible light irradiation. The 1 O2 generation efficiency of Ag7(MBISA)6 NCs was higher than those of the following known water-soluble metal NCs: bovine serum albumin(BSA)-Au25 NCs,BSA-Ag8 NCs, BSA-Ag14 NCs,Ag25(dihydrolipoic acid)14 NCs,Ag35(glutathione)18 NCs,and Ag75(glutathione)40 NCs. The metal NCs examined in this study showed the following order of 1 O2 generation efficiency under white light irradiation: Ag7(MBISA)6 BSA-Ag14 Ag75(SG)40 Ag35(SG)18 BSA-Au25 BSA-Ags(not detected) and Ag2 s(DHLA)14(not detected). For further improving the 1 O2 generation of Ag7(MBISA)6 NCs, we developed a novel fluorescence resonance energy transfer(FRET) system by conjugating Ag7(MBISA)6 NCs with quinacrine(QC)(molar ratio of Ag NCs to QC is 1 : 0.5). We observed the FRET process,from QC to Ag7(MBISA)6 NCs,occurring in the conjugate. That is,the QC works as a donor chromophore,while the Ag NCs work as an acceptor chromophore in the FRET process. The FRET-mediated process caused a 2.3-fold increase in 1 O2 generation compared to that obtained with Ag7(MBISA)6 NCs alone. This study establishes a general and simple strategy for improving the PDT activity of metal NC-based photosensitizers.     

Singlet oxygen addition to homoallylic substrates in solution and microemulsion: novel secondary reactions

The photooxygenation of three homoallylic substrates, the γ,δ-unsaturated ketone 1a, nitrile 2a, and the γ,δ-unsaturated ester 3a was investigated in homogeneous solution and in microemulsion (for 1a). Two secondary reaction pathways were detected for the allylic hydroperoxides of type b and c, respectively. The cyclization reactions of 1b and 2b to the 1,2-dioxanes 1d and 2d followed well-known reaction patterns, whereas the base-catalyzed epoxide (1e-3e) formation from the tertiary allylic hydroperoxides 1c-3c is a unprecedented reaction type.     

Recent progress in tumor photodynamic immunotherapy

Photodynamic therapy(PDT) is a promising alternative approach for effective cancer treatment,which can directly destroy local tumor cells due to the generation of cytotoxic singlet oxygen and reactive oxygen species(ROS) in the tumor cells.Intriguingly,PDT-mediated cell death is also associated with anti-tumor immune response.Howeve r,immunosuppre s sion of tumor microe nvironment is able to limit the immune response induced by PDT,it is therefore necessary to combine with immunocheckpoint inhib...     

Syntheses and absorption-structure relationships of some new photosensitizer cyanine dyes

New biheterocyclic compound was synthesized as starting material to prepare new photosensitizers mono-, tri-, substituted tri-, azadimethine and mixed cyanine dyes. Absorption-structure relationship of the synthesized cyanine dyes were determined by studying their electronic spectral behaviour in ethanol. The structure of the compounds were identified by elemental analysis, IR and¹HNMR spectral data.     

菁染料光解机理的前线分子轨道研究

通过SCF PM3和AM1 MO计算研究，揭示了正离子型菁染料与相应中性化合物在分子几何、电荷分布、前线分子轨道能级和组成等方面的不同特点。特别是根据前线轨道理论和成键三原则，通过比较氧的激发单态（^1O2^*)或超氧负离子自由基（O2^-.）与标题物之间的前线轨道相互作用，阐明了标题物的光解机理和正离子较中性化合物光稳定的根由。结论与实验事实良好相符。