Anionic Cyanine Research Articles

Heptamethine Cyanine Dye-Doped Single-Walled Carbon Nanotube Electrodes for Improving Performance of HTL-Free Perovskite Solar Cells

Perovskite solar cell (PSC) technology holds great promise with continuously improving power conversion efficiency; however, the use of metal electrodes hinders its commercialization and the development of tandem designs. Although single-walled carbon nanotubes (SWCNTs), as one-dimensional materials, have the potential to replace metal electrodes in PSCs, their poor conductivity still limits their application. In this study, the near-infrared (NIR)-absorbing anionic heptamethine cyanine dye-doped SWCNTs functioned in a dual role as an efficient charge-selective layer and electrode in PSCs. Benefiting from the improvement in conductivities and matched energy level of doped-SWCNT, the dual-role SWCNT electrodes applied to PSCs achieved a better performance than the undoped PSCs with a higher short circuit current (JSC) and fill factor (FF).

Synergistic Phototherapy Using Zwitterionic Crystalline Nanoaggregates of Orthogonal Donor–Acceptor Small‐Molecule Dyads

AbstractDeveloping nanophotosensitizer (nanoPS) for synergistic phototherapy by leveraging the aggregation of small‐molecule dyes is compelling frontier in precision medicine, but challenges remain due to the limited understanding of the interactions between molecular structure, assembly behavior, and theranostic function. Here, the concept of “spin‐orbit charge‐transfer intersystem crossing (SOCT‐ISC) in crystalline aggregates” is introduced, which significantly enhances photodynamic (PD) and photothermal (PT) properties of small‐molecule‐based nanoPS. Specifically, a cationic pyridine (Py) group is incorporated at the meso‐position of a tricyanofuran (TCF)‐containing anionic heptamethine cyanine (TCF‐Cy7‐TCF) dye to construct an orthogonal charge‐transfer dyad (TCF‐Cy7(Py)‐TCF), boosting triplet state formation through SOCT‐ISC mechanism to enhance the PD properties. Remarkably, the zwitterion moieties impart TCF‐Cy7(Py)‐TCF with high crystallinity even at ultralow concentrations, dictating its stacking behavior within aggregates and enhancing both PT and PD properties. The TCF‐Cy7(Py)‐TCF nanoaggregates exhibit superior singlet oxygen quantum yield (0.8% vs 0.2%) and photothermal conversion efficiency (55.06% vs 7.78%) compared to TCF‐Cy7‐TCF. Impressively, TCF‐Cy7(Py)‐TCF preferentially accumulates at tumor sites, yielding high signal‐to‐background ratios for tumor imaging in NIR‐I and NIR‐II windows, with minimal nonspecific binding. Finally, in vivo experiments confirm TCF‐Cy7(Py)‐TCF nanoaggregates function as nanoPS for synergistic phototherapy, offering a simple yet effective strategy to design single‐component PS for clinical translation.

A Cyanine Dye for Highly Specific Recognition of Parallel G-Quadruplex Topology and Its Application in Clinical RNA Detection for Cancer Diagnosis.

G-quadruplex (G4), an unconventional nucleic acid structure, shows polymorphism in its topological morphology. The parallel G4 topology is the most prevalent form in organisms and plays a regulatory role in many biological processes. Designing fluorescent probes with high specificity for parallel G4s is important but challenging. Herein, a supramolecular assembly of the anionic cyanine dye SCY-5 is reported, which selectively identifies parallel G4 topology. SCY-5 can clearly distinguish parallel G4s from other G4s and non-G4s, even including hybrid-type G4s with parallel characteristics. The high specificity mechanism of SCY-5 involves a delicate balance between electrostatic repulsion and π-π interaction between SCY-5 and G4s. Using SCY-5, cellular RNA extracted from peripheral venous blood was quantitatively detected, and a remarkable increase in RNA G4 content in cancer patients compared to healthy volunteers was confirmed for the first time. This study provides new insights for designing specific probes for parallel G4 topology and opens a new path for clinical cancer diagnosis using RNA G4 as a biomarker.

Activatable NIR Fluorescence Probe for Epinephrine Detection and Bioimaging Based on Anionic Heptamethine Cyanine.

Epinephrine (EP) is an essential catecholamine in the human body. Currently, most EP detection methods are not suitable for in vivo detection due to material limitations. An organic small molecule fluorescent probe based on a chemical cascade reaction for the detection of EP was designed. Anionic heptamethine cyanine dye was selected as a fluorescent dye because of its NIR fluorescence emission with excellent biocompatibility. The secondary amine of EP nucleophilically attacks the carbonate of the probe with its stronger nucleophilicity and further undergoes intramolecular nucleophilic cyclization to release the fluorophore. Other substances containing only primary amines or no β-OH lack reaction competitiveness due to their weaker nucleophilicity or inability to undergo further cyclization. The fluorescence recovery of the probe was linearly related to the EP concentration of 2-75 μmol/L. The detection limit was 0.4 μmol/L. The recovery rate was 94.78-111.32%. Finally, we successfully achieved bioimaging of EP in living cells and EP analogue in nematodes.

Synthesis of Near-Infrared-Absorbing Anionic Heptamethine Cyanine Dyes with Trifluoromethyl Groups.

A novel anionic heptamethine cyanine (HMC) dye with two trifluoromethyl groups that selectively absorb near-infrared light is synthesized. When contrasted with previously studied anionic HMC dyes with substituents such as methyl, phenyl, and pentafluorophenyl groups, the trifluoromethylated dye displays a red-shifted maximum absorption wavelength (for instance, 948 nm in CH2Cl2) along with enhanced photostability. Furthermore, HMC dyes with broad absorption in the near-infrared region are synthesized by combining a trifluoromethylated anionic HMC dye with a cationic HMC dye as a counterion.

Spectral features of the dispersion of carbocyanine dye J-aggregates in a liquid crystal matrix

Formation of J-aggregates of the anionic cyanine dye TDBC in a nematic liquid crystal (LC) matrix is reported, with analysis of optical-fluorescent and electro-optical properties of the obtained novel material. The TDBC J-aggregates show a rather long lifetime and high photostability in the nematic matrix. The electro-optical characteristics of the LC matrix are substantially modified, with the Fredericks transition threshold slightly increased, which is, on the other hand, accompanied by the improvement of the optical contrast. Only a minor effect of the forming J-aggregates on the molecular order of the LC structure could be noted.

Anionic Cyanine J-Type Aggregate Nanoparticles with Enhanced Photosensitization for Mitochondria-Targeting Tumor Phototherapy.

Cyanines have been widely used as the photosensitizers (PSs) in the biomedical field, but controlling their molecular aggregates in nanoparticles (NPs) remains a major challenge. Moreover, the impact of aggregate behaviors of cyanines on the photosensitization is still unclear. Herein, the first anionic cyanine PSs based on a tricyanofuran end group have been designed by achieving supramolecular J-type aggregates in NPs via counterion engineering. Our results indicate that J-type aggregates in NPs can not only bring significantly red-shifted emission, negatively charged surface, and high photostability, but also enable a significant 5-fold increase in singlet oxygen generation efficiency compared to that in the nonaggregate state, providing strong experimental evidence for the superiority of J-aggregates in enhancing photosensitization. Thus, combined with the mitochondria-targeting ability, the J-type aggregate NPs show remarkable in vivo antitumor phototheranostic efficacy, making them have a potential for clinical use.

Anionic Cyanine J‐Type Aggregate Nanoparticles with Enhanced Photosensitization for Mitochondria‐Targeting Tumor Phototherapy

AbstractCyanines have been widely used as the photosensitizers (PSs) in the biomedical field, but controlling their molecular aggregates in nanoparticles (NPs) remains a major challenge. Moreover, the impact of aggregate behaviors of cyanines on the photosensitization is still unclear. Herein, the first anionic cyanine PSs based on a tricyanofuran end group have been designed by achieving supramolecular J‐type aggregates in NPs via counterion engineering. Our results indicate that J‐type aggregates in NPs can not only bring significantly red‐shifted emission, negatively charged surface, and high photostability, but also enable a significant 5‐fold increase in singlet oxygen generation efficiency compared to that in the nonaggregate state, providing strong experimental evidence for the superiority of J‐aggregates in enhancing photosensitization. Thus, combined with the mitochondria‐targeting ability, the J‐type aggregate NPs show remarkable in vivo antitumor phototheranostic efficacy, making them have a potential for clinical use.

Photostability and Halochromic Properties of Near‐Infrared Absorbing Anionic Heptamethine Cyanine Dyes

AbstractWe synthesized near‐infrared‐absorbing anionic heptamethine cyanine (HMC) dyes and investigated their photostability and halochromic properties in detail. Upon changing the methyl groups of the anionic HMC dye to phenyl or perfluorophenyl groups, the maximum absorption wavelengths of the dye solutions were red‐shifted and dye photostability in solution under white LED irradiation at 25 °C was improved. The anionic HMC dye featuring methyl groups presented halochromic properties in solution, and the solution color changed from green to yellow in the presence of acids. This is the first reported anionic HMC dye with halochromic properties. Furthermore, we produced a stimuli‐responsive filter paper adsorbed with anionic HMC dyes that changed color from green to yellow upon exposure to HCl gas and from yellow to green upon subsequent exposure to NH3 gas.

Elementary Photochemical Processes Involving meso-Substituted Anionic Cyanine Dyes in Solutions and in Complexes with Serum Albumins

Elementary Photochemical Processes Involving meso-Substituted Anionic Cyanine Dyes in Solutions and in Complexes with Serum Albumins

Comparative study of the interaction of some meso-substituted anionic cyanine dyes with human serum albumin

Spectral-fluorescent properties of the meso-substituted anionic cyanine dye 3,3′-di-(γ-sulfopropyl)-4,5,4′,5′-dibenzo-9-methylthiacarbocyanine betaine (DMC) were studied in solutions and in the presence of human serum albumin (HSA). The properties of DMC were compared with those of the previously studied meso-substituted anionic dyes 3,3′-di(γ-sulfopropyl)-4,5,4′,5′-dibenzo-9-ethylthiacarbocyanine betaine (DEC), 3,3′-di-(γ-sulfopropyl)-9-methylthiacarbocyanine betaine (MTC) and 3,3′-di-(γ-sulfopropyl)-5,5′-diphenyl-9-ethyloxacarbocyanine betaine (OCC), which were studied here in more detail. In aqueous solutions, DMC, like DEC, is prone to dimerization; it also forms H– and J-aggregates. The noncovalent interaction of DMC with HSA leads to decomposition of the dimers with a shift in the cis–trans isomeric equilibrium toward the trans-monomer complexed with HSA, which is accompanied by a significant increase in fluorescence. The spectral-fluorescent data were used to estimate the binding constants of the dyes with HSA and other characteristics of the dyes, which are important when used as probes for HSA. The effect of structural rearrangements of HSA upon denaturation by urea on the spectral-fluorescent properties of the dyes was studied. Molecular docking of the dye–HSA systems was performed. A comparative assessment of the prospects for the use of the dyes as spectral-fluorescent probes for HSA in vitro was carried out.

Determination of phosphate anions with a near-infrared heptamethine cyanine dye in a neutral aqueous solution

A novel strategy was developed for the detection of phosphate anions with anionic heptamethine cyanine and Tb3+ in the NIR region.

Optical properties of molecular nanocrystals consisting of J-aggregates of anionic and cationic cyanine dyes.

We report results of experimental studies of the photoabsorption, photoluminescent and photoelectric properties of a new type of multilayer molecular nanocrystals, consisting of highly ordered J-aggregates of one anionic and two cationic J-aggregates of cyanine dyes. In contrast to conventional J-aggregated dyes the multichromic nanocrystals synthesized in this work, are capable of efficient light absorption in three excitonic bands of the visible and near-IR spectral ranges. The spectral peak positions in the absorption bands can be controlled by appropriately selecting a set of dyes a molecular crystal is made of. Our investigations of the photoelectric properties of multichromic crystals have shown that each of them can potentially be used as a photosensitive layer of a photocell with photoconductivity in three peaks of excitonic absorption. The synthesized nanocrystals are attractive for the creation of thin-film organic photodetectors with a large photosensitive area and varied photoabsorption spectra, excitonic waveguides and for some other applications in organic and hybrid photonics and optoelectronics.

Optical and photoelectric properties of multichromic cyanine dye J-aggregates

We report the results of investigation of spectra and kinetics of photoluminescence as well as of photoabsorption and photoelectric properties for multichromic molecular crystals consisting of J-aggregates of three cyanine dyes with various structures. An original ‘self-assembly’ method is used for fabricating such prolate ordered structures with a thickness of 5 – 100 nm, width of 0.1 – 5 μm, and length of 50 – 300 μm. The method is based on the formation of the anionic platform in a water solution, which absorbs light in the blue spectrum range and comprises J-aggregates of magnesium complexes of anionic cyanine dye. Then the ‘matrix synthesis’ is used for coating its surface with J-aggregates of the two cationic dyes that have the absorption maxima in the green and red spectral ranges. It is shown that each of the multichromic organic crystals produced in this way is a multilayer photoelement, which possesses photoconductivity in three excitonic absorption maxima (in the blue, green, and red spectral ranges) with the external quantum efficiency varying from 2.7 % to 6.1 %. The results obtained provide a basis for technological development of highly-ordered molecular structures, which are promising for using in organic and hybrid photonics and optoelectronics including thin-film photo-converters operating in wide spectral ranges.

(Invited) Individualized Low-Dimensional Carbon Allotropes: Enabling Ground State and Excited State Charge Transfer By NIR Absorbing Heptamethine Cyanine

At the focal point of our studies are mutual interactions between an anionic heptamethine cyanine and individualized single walled carbon nanotubes (SWCNT) / exfoliated nanographene (NG). Unprecedented is the distinct NIR absorption of the heptamethine cyanine, which assists in visualizing the electronic interactions in the ground state with ease and precision. In statistical Raman assays, we conclude from downshifted 2D- and G-modes for SWCNTs, as well as, upshifted 2D- and downshifted G-modes for NG that these electronic interactions result in stable n-doping of SWCNTs / NG . Key to this shift of charge density is the electron donating character of the heptamethine cyanine. In the excited state, a complete, but metastable transfer of charges is accompanied by a several nanoseconds lived radical ion pair state. Note such a time domain has never been realized, for example, in NGs to this date.

Nanoscale Photoconverters for the IR Region of the Spectrum Based on Mixed J-Aggregates of Indolenine Dyes

It is shown that anionic indoheptamethine cyanine dyes of different structures form mixed metalcomplex J-aggregates in aqueous solutions under the action of multiply charged inorganic cations. By measuring the photoconductivity of layers from mixed metal-complex J-aggregates, it has been found that the photoresponse of nanoscale photoconverters for the IR region of the spectrum increases significantly in comparison with the indices for the J-aggregate of the individual dye. It is concluded that the formation of new highly organized structures by the self-assemblage of J-aggregates of several dyes can be considered a promising nanotechnology method for the production of organic semiconductors with improved photo properties.

J-Aggregates of Indoheptamethine Cyanine Dye

The effect of doubly charged inorganic and organic cations on the aggregation of anionic indoheptamethine cyanine dyes has been studied in aqueous solutions. It is shown that the effective formation of J-aggregates with narrow exciton absorption bands in the IR region of the spectrum with λmax = 920 nm is characteristic only of a dye with SO 3 - groups in the 6,6′-positions of the benzoindolenine ring. It is found that bis-quaternary salt based on α-picolinium is particularly effective as a J-aggregating agent and causes J-aggregation at a concentration close to the dye concentration. It follows that the introduction of sulfogroups at the 6,6′-positions of the benzoindolenine ring creates optimal conditions for packing the molecules of the indolenine dye into a highly organized structure of a “brickwork” type under the action of multiply charged cations. It is shown that the J-aggregates of the indoheptamethine cyanine dye are photoelectric converters for the IR region of the spectrum.

Aggregation of Anionic Cyanine Dyes by Electron-Withdrawing Organic Polycations

It is shown that bis-quaternary salts of 4,4′-dipyridyl (viologens) stimulate the J-aggregation of anionic cyanine dyes in an aqueous solution. It is concluded that the behavior of multiply charged inorganic and organic cations is similar: both types of polycations result in the self-assembly of ordered J-aggregate structures from dimers. It is found that multichromic J-aggregates with the participation of cationic cyanine dyes are formed on the “platform” of J-aggregates built of anionic cyanine dyes and dications of viologens. Thus, we discuss the self-assembly of highly organized structures in which, along with photosensitive exciton semiconductors from organic dyes, π-conjugated organic molecules are included that can participate in secondary dark processes of separation of charges of Frenkel excitons.

Heptamethine Cyanine Dyes in the Design of Photoactive Carbon Nanomaterials.

Near-infrared (NIR) absorbing nanomaterials, built from anionic heptamethine cyanine dyes and single-walled carbon nanotubes or few-layer graphene, are presented. The covalent linkage, using 1,3-dipolar cycloaddition reactions, results in nanoconjugates that synchronize the properties of both materials, as demonstrated by an in-depth characterization study carried out by transmission electron microscopy, atomic force microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. UV–vis–NIR and Raman spectroscopies further confirmed the unique electronic structure of the novel photoactive nanomaterials.

Non-chiral Polymer-induced Chirality Enhancement in Lipidic Nanotube-based Hydrogel System

Induced chirality of the cationic glutamide-based lipidic nanotube was enhanced through the formation of a hetero-network hydrogel with terminal alkylated non-chiral hydrophilic polymer, which was detected by the chiral interaction between the anionic cyanine dye and the nanotube.