New 1,3,4‐Oxadiazinoisoquinoline Methine Cyanine Dyes: Synthesis,Photosensitivity and Antibacterial Activity

New heterocyclic ring system including 1,3,4‐oxadiazino[6,5‐c]isoquinoline was prepared and employed as a precursor for preparation of monomethine and trimethine cyanine dyes. The structure of the new compounds was characterized via elemental analysis and mass, ¹H‐NMR, and ¹³C‐NMR spectroscopy. The photosensitivity (electronic transitions inside the dye molecule due to photon absorption) of the new methine cyanine dyes was investigated by studying their visible spectra in absolute ethanol and showed its maxima in the visible range of the spectrum with relatively strong absorption bands. The antibacterial activity of the newly synthesized compounds was evaluated against some bacterial strains, resulting in a promising antibacterial efficacy that recommend the tested compounds as new candidates for further pharmaceutical evaluations.     

Synthesis and Characterization of γ‐Heteroaryl‐substituted Pentamethine Cyanine Dyes with Carboxy or Methoxycarbonyl Substituents at the Two Heterocyclic End Groups

Seven novel pentamethine cyanine dyes with 3,5‐dimethylpyridinium‐1‐yl, pyridinium‐1‐yl, and 1‐quinolinum‐1‐yl substituents in the γ position of the methine chain containing ester or carboxylic acid groups in the ring of the dyes were synthesized via a three‐step procedure. The visible spectral behavior of the pentamethine cyanine dyes was examined in DMSO. Elemental analysis, IR, ¹H‐NMR, ¹³C‐NMR, and mass spectral (MS) data confirmed the molecular structure of the newly synthesized compounds.     

Synthesis of Asymmetric Monomethine Cyanine Dyes with Red‐Shifted Optical Properties

Six novel asymmetrical monomethine cyanine dyes were synthesized via the condensation reaction of 1‐butyl‐2‐(methylthio)benzo[c,d]indol‐1‐ium iodide and various 1,5‐substituted indolenine salts under basic conditions. The dyes were characterized using UV–vis spectroscopy, fluorescence, ¹H NMR, ¹³C NMR, and mass spectrometry; furthermore, the purity of these compounds was observed using LC/ELSD/MS.     

Cyanine‐Like Dyes with Large Bond‐Length Alternation

Herein, the synthesis and properties of alkyne‐bridged carbocations, which are analogous in structure to cyanine dyes, are reported. An alkene‐bridged dye, linked at the third position of the indole, was also synthesized as a reference compound. These new carbocations are stable under ambient conditions, allowing characterization by UV/Vis and NMR (¹H and ¹³C) spectroscopies. These techniques revealed a large degree of delocalization of the positive charge, similar to a previously reported porphyrin carbocation. The linear and nonlinear optical properties are compared with cyanine dyes and triarylmethyl cations, to investigate the effects of the bond‐length alternation and the overall molecular geometry. The value of Re(γ), the real part of the third‐order microscopic polarizability, of ?1.3×10^?33 esu for the alkyne‐linked cation is comparable to that of a cyanine dye of similar length. Nondegenerate two‐photon absorption spectra showed that the alkene‐bridged dye exhibited characteristics of cyanines, whereas the alkyne‐bridged dye is reminiscent of octupolar chromophores, such as the triarylmethyl carbocation brilliant green. Such attributes were confirmed and rationalized by quantum chemical calculations.     

Studies of 2‐Azaazulenium Derivatives: Unsymmetrical Trimethine Cyanine Dyes Bearing a 2‐Azaazulenium Moiety as One of the Terminal Groups

We report here the synthesis of a series of symmetrical and unsymmetrical trimethine cyanine dyes derived from 2‐azaazulene, combined spectral and quantum‐chemical investigations of their molecular geometry and electron structure, as well as the nature of the lowest electron transitions. Based on the analysis of both calculations and experimental data obtained from absorption and ¹³C NMR spectra, it was concluded that the 2‐azaazulene residue can be treated as a weakly basic terminal group; its donor properties are provided with the participation of the HOMO?1, in contrast to the typical Brooker’s terminal residues with their donor HOMOs. The new classification of the terminal groups of cyanine dyes, and hence the classification of types of unsymmetrical cyanines, is proposed. It is shown that the nature of the higher electron transitions (delocalized or local) in the cyanine dyes depends on their type. In the unsymmetrical trimethine cyanine of the mixed type, negative deviations are observed in their absorption spectra.     

Synthesis,Absorption Spectra Studies and Biological Activity of Some Novel Conjugated Dyes

Novel monomethine 2a‐f , dimethine 4a‐f and tetramethine 6a‐h cyanine dyes were prepared as conjugated dyes. Such dyes incorporating coumarin and/or quinoline derivatives 1a‐d . These dyes were synthesized to study their spectral behavior, solvatochromism and biological activity. These dyes are characterized by elemental analysis, IR, ¹H NMR and mass‐spectra.     

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.     

含叔丁基吡喃鎓方酸菁染料的合成及溶解性能研究

合成了四个对称及不对称含叔丁基吡喃鎓方酸的菁染料,通过光谱和元素分析确定其结构,测定了它们的紫外-可见吸收光谱、熔点和溶解性能。结果表明吡喃鎓方酸菁染料比一般菁染料具有更长的吸收波长和更好的溶解性能。用Dye2的单晶分子堆积图解释了染料的熔点反常现象。     

Viscosity dependent radiationless relaxation rate of cyanine dyes. A picosecond laser spectroscopy study

The viscosity dependent radiationless relaxation of several cyanine dyes has been studied by picosecond laser spectroscopy. It was found that the relaxation rate is proportional to η^?α. The value of α, however, is not constant for a certain dye molecule, but is strongly dependent on the kind of solvent used. In n-alcohols for instance α is typically about 1. In glycerol/methanol or glycerol/water mixtures on the other hand α ≈ 0.5. A comparison is made with literature data on orientational relaxation lifetimes of some dyes in similar solvents. It is shown that the radiationless relaxation of cyanine dyes and the orientational relaxation of for instance xanthene dyes changes in roughly the same way as the solvent is changed. This is taken as proof of the proposal that a torsional motion of the heterocyclic quinolyl rings is the main course of the viscosity dependent relaxation of the cyanine dyes studied.     

Charge distribution and 13C NMR spectra of cyanine dyes with bridging groupings in the chromophore

The electronic structure of cationoid and anionoid cyanine dyes was calculated by the CNDO/2 method. The calculation results were compared with the data of the ¹³C NMR spectra. It was shown that the anionoid dyes of the malonocyanine class have all the inherent properties of a polymethine state, i.e., alternation of charges and leveling of bonds, and these are also characteristic of cationic streptopolymethines. According to the calculation data, the introduction of bridging groupings causes considerable changes in the electronic structure of the cyanine dyes, as confirmed by the results of the study of their ¹³C NMR spectra.Translated from Teoreticheskaya i Ékperimental'naya Khimiya. Vol. 23, No. 6, pp. 687–692, November–December, 1987.     

Synthesis and Characterization of Some Novel Dichromophoric Cyanine Dyes

Here, the synthesis of two novel series of dichromophoric cyanine dyes were reported. The first series of novel bis-azacyanine dyes 3a–d was afforded by reaction of 2-(1,3,3-trimethyle indoline-2-ylidene)acetaldehyde with diaminoaromatics, and the second series of novel bis-diazacyanine dyes 4a–d was obtained using quaternization of an amine group in disazo compounds, which were produced by the reaction of disazoaromatics with 2-methylene-1,3,3-trimethyle indoline. The products were identified by ¹H NMR, ¹³C NMR, infrared, UV-vis, and mass spectroscopy.     

Synthesis and Characterization of New γ-Substituted Pentamethine Cyanine Dyes

Three novel pentamethine cyanine dyes with 3,5-dimethylpyridinium-1-yl and 4-benzylpyridinium-1-yl substituents in γ position of the methine chain were synthesized via a three-step procedure. The visible spectral behavior of these pentamethine cyanine dyes was examined in DMSO. Elemental analysis, IR, ¹H-NMR, ¹³C-NMR, and Mass spectral data confirmed the molecular structure of the newly synthesized compounds.     

Protein purification by aminosquarylium cyanine dye‐affinity chromatography

The most selective purification method for proteins and other biomolecules is affinity chromatography. This method is based on the unique biological‐based specificity of the biomolecule–ligand interaction and commonly uses biological ligands. However, these ligands may present some drawbacks, mainly because of their cost and lability. Dye‐affinity chromatography overcomes the limitations of biological ligands and is widely used owing to the low cost of synthetic dyes and to their resistance to biological and chemical degradation. In this work, immobilized aminosquarylium cyanine dyes are used in order to exploit affinity interactions with standard proteins such as lysozyme, α‐chymotrypsin and trypsin. These studies evaluate the affinity interactions occurring between the immobilized ligand and the different proteins, as a reflection of the sum of several molecular interactions, namely ionic, hydrophobic and van der Waals, spread throughout the structure, in a defined spatial manner. The results show the possibility of using an aminosquarylium cyanine dye bearing a N‐hexyl pendant chain, with a ligand density of 1.8 × 10^?2 mmol of dye/g of chromatographic support, to isolate lysozyme, α‐chymotrypsin and trypsin from a mixture. The application of a decreasing ammonium sulfate gradient resulted in the recovery of lysozyme in the flowthrough. On the other hand, α‐chymotrypsin and trypsin were retained, involving different interactions with the ligand. In conclusion, this study demonstrates the potential applicability of ligands such as aminosquarylium cyanine dyes for the separation and purification of proteins by affinity chromatography. Copyright © 2013 John Wiley & Sons, Ltd.     

菁染料和份菁染料薄膜的光稳定性研究

利用UV-Vis吸收光谱仪和光化学反应器研究了菁染料和份菁染料薄膜的光降解动力学.与相应的份菁染料相比,携带正电荷的菁染料薄膜具有相对较好的光稳定性.运用量子化学中的SCF-MO-PM3方法,全优化计算了这些染料的分子几何构型和电子结构,并解释了染料的光稳定性与其分子结构的关系.     

Key Structural Elements of Unsymmetrical Cyanine Dyes for Highly Sensitive Fluorescence Turn‐On DNA Probes

Unsymmetrical cyanine dyes, such as thiazole orange, are useful for the detection of nucleic acids with fluorescence because they dramatically enhance the fluorescence upon binding to nucleic acids. Herein, we synthesized a series of unsymmetrical cyanine dyes and evaluated their fluorescence properties. A systematic structure–property relationship study has revealed that the dialkylamino group at the 2‐position of quinoline in a series of unsymmetrical cyanine dyes plays a critical role in the fluorescence enhancement. Four newly designed unsymmetrical cyanine dyes showed negligible intrinsic fluorescence in the free state and strong fluorescence upon binding to double‐stranded DNA (dsDNA) with a quantum yield of 0.53 to 0.90, which is 2 to 3 times higher than previous unsymmetrical cyanine dyes. A detailed analysis of the fluorescence lifetime revealed that the dialkylamino group at the 2‐position of quinoline suppressed nonradiative decay in favor of increased fluorescence quantum yield. Moreover, these newly developed dyes were able to stain the nucleus specifically in fixed HeLa cells examined by using a confocal laser‐scanning microscope.     

Synthesis and Spectral Behaviour of Some New Uninuclear Pyrimidine 2[2(4)]‐Mono(Tri)‐Methine Cyanine Dyes

New unsymmetrical 2[2(4)]‐mono‐and tri (substituted tri)‐methine cyanine dyes incorporating 1,2,5,6‐tetrahydro‐4,6‐diaryl pyrimidine (pyrimidinium‐1‐yl salt)‐2‐one were prepared. Structural determination was carried out by elemental analysis, IR and ¹H NMR spectral data. The spectral behaviour of all the synthesized cyanines was examined in 95% ethanol.     

Combination of Cyanine Behaviour and Giant Hyperpolarisability in Novel Merocyanine Dyes: Beyond the Bond Length Alternation (BLA) Paradigm

Merocyanine dyes that exhibit antithetic cyanine‐like behaviour and giant first‐order hyperpolarisability (β) values have been designed. These cyanine‐type dyes open up an intriguing route towards molecular‐based electro‐optic materials as well as new second‐harmonic generation dyes for imaging.     

Synthesis and Visible Spectral Behaviour of Some New N‐Bridgehead Heterocyclic Cyanine Dyes Incorporating Pyrazolo (4,5‐b) Indolizine (Benzoindolizine)

The new unsymmetrical N‐bridgehead, apo (zeromethine), mono‐methine, dimethine, meso substituted tetramethine and styryl cyanine dyes incorporating pyrazolo (4,5‐b) indolizine (benzoindolizine) nuclei were prepared. Structural confirmation was carried out by elemental analyses, IR, H‐NMR, mass spectra and ¹³C‐NMR with the aid of carbon DEPT spectral data. The visible absorption spectra for the newly synthesized cyanines were examined in 95% ethanol.     

The synthesis and characterization of novel coumarin-containing cyanine dyes via “Click” chemistry

Four novel cyanine dye derivatives (C-Cy(1–4)) in which a coumarin moiety is attached to benzoindole ring of asymmetric trimethine cyanine dyes or hemicyanine dye by 1,2,3-triazole have been successfully synthesized via “Click” reaction between the corresponding alkyl-end cyanine dyes and 3-azidocoumarin. Six reaction systems were employed to find the suitable “Click” conditions of cyanine dyes. It was found that the combination of DMF, CuI and di-i-propylethylamine (DIPEA) was the most excellent system for “Click” reaction. All of the compounds were characterized by ¹H-NMR, MS, UV and FL.     

Synthesis and Photochemical Evaluation of Iodinated Squarylium Cyanine Dyes

Several (multiply) iodinated squarylium cyanine dyes of type 1 and 8 (see Scheme and Table), derived from 1,3‐benzothiazole and 6‐iodo‐1,3‐benzothiazole, were synthesized as potential new photosensitizers, with absorptions in the 700‐nm region. Their ability to generate singlet oxygen (¹O₂) was assessed by luminescence‐decay measurement in the near‐IR. Some of these new dyes show interesting photophysical properties, and may be potentially used in photodynamic therapy (PDT).