Cationic Cyanine Dye Research Articles

Cyclopentene ring effects in cyanine dyes: a handle to fine-tune photophysical properties.

The aim of this study is to investigate the photophysical properties of a cyanine dye analogue by performing first-principles calculations based on density functional theory (DFT) and time dependent-DFT. Cationic cyanine dyes are the subject of great importance due to their versatile applications and the tunability of their photophysical properties, such as by modifying their end groups and chain length. An example of this is the vinylene shift, which is experimentally known for these molecules, and it consists of a bathochromic (red) shift of approximately 100 nm of the 0-0 vibronic transition when a vinyl group is added to the polymethine chain. Our study shows that when the saturated moiety C2H4 of the cyclopentene ring is added to the chain, it interacts with the conjugated π-system, resulting in a smaller HOMO-LUMO gap. Here, we demonstrate the origin of this interaction and how it can be used to fine tune the absorption energies of this class of dyes.

Effect of Fucoidan on the Mitochondrial Membrane Potential (ΔΨm) of Leukocytes from Patients with Active COVID-19 and Subjects That Recovered from SARS-CoV-2 Infection.

Fucoidan is a polysaccharide obtained from marine brown algae, with anti-inflammatory, anti-viral, and immune-enhancing properties, thus, fucoidan may be used as an alternative treatment (complementary to prescribed medical therapy) for COVID-19 recovery. This work aimed to determine the ex-vivo effects of treatment with fucoidan (20 µg/mL) on mitochondrial membrane potential (ΔΨm, using a cationic cyanine dye, 3,3′-dihexyloxacarbocyanine iodide (DiOC6(3)) on human peripheral blood mononuclear cells (HPBMC) isolated from healthy control (HC) subjects, COVID-19 patients (C-19), and subjects that recently recovered from COVID-19 (R1, 40 ± 13 days after infection). In addition, ex-vivo treatment with fucoidan (20 and 50 µg/mL) was evaluated on ΔΨm loss induced by carbonyl cyanide 3-chlorophenylhydrazone (CCCP, 150 µM) in HPBMC isolated from healthy subjects (H) and recovered subjects at 11 months post-COVID-19 (R2, 335 ± 20 days after infection). Data indicate that SARS-CoV-2 infection induces HPBMC loss of ΔΨm, even 11 months after infection, however, fucoidan promotes recovery of ΔΨm in PBMCs from COVID-19 recovered subjects. Therefore, fucoidan may be a potential treatment to diminish long-term sequelae from COVID-19, using mitochondria as a therapeutic target for the recovery of cellular homeostasis.

Intercalation of a Cationic Cyanine Dye Assisted by Anionic Surfactants within Mg-Al Layered Double Hydroxide.

An original route for the intercalation of a 1,1′-diethyl-2,2′-cyanine iodide (PIC) cationic dye, through the use of anionic surfactants as vector/carrier phases, within Mg–Al layered double hydroxide (LDH) was investigated. From the data acquired from complementary techniques (X-ray diffraction, infrared and UV–visible spectroscopies, thermogravimetry, and fluorimetry), it appears that both the intercalation and aggregation states of the cationic dye within the internal structure of LDH mainly depend on both the surfactant state (monomer form or spherical micelle) and its amount. The intercalation of PIC at a low molar ratio to the anionic surfactant leads to the formation of J-aggregates with singular fluorescence properties that mainly depend on the nature of the anionic surfactant used for the co-intercalation process. The results obtained in this study open new routes for the intercalation of cationic species, assisted by anionic surfactants, within LDHs.

Covalent bonding effects on spectral, photophysical and generation properties of indocarbocyanine dyes in polyurethanes

Spectral, photophysical and generation properties of symmetrical cationic cyanine dyes have been investigated in the polyurethane matrices, similar by the structure, but different by the polymerization method. The cyanine dye doped polyurethane, synthesized by a polycondensation reaction, provides laser active elements with significantly improved photostability, efficiency and operation lifetime, compared to those for the polyurethane acrylate matrix, hardened by a radical photopolymerization method. Changing the liquid (ethanol) medium to polymers causes an increase of fluorescence quantum yield and efficiency. For the first time, covalent bonding between a cyanine dye and a polyurethane has been studied, and high fluorescence quantum yield and generation efficiency have been observed.

Bioinspired Scaffolding by Supramolecular Amines Allows the Formation of One- and Two-Dimensional Silica Superstructures.

Silica materials attract an increasing amount of interest in (fundamental) research, and find applications in, for example, sensing, catalysis, and drug delivery. As the properties of these (nano)materials not only depend on their chemistry but also their size, shape, and surface area, the controllable synthesis of silica is essential for tailoring the materials to specific applications. Advantageously, bioinspired routes for silica production are environmentally friendly and straightforward since the formation process is spontaneous and proceeds under mild conditions. These strategies mostly employ amine‐bearing phosphorylated (bio)polymers. In this work, we expand this principle to supramolecular polymers based on the water‐soluble cationic cyanine dye Pinacyanol acetate. Upon assembly in water, these dye molecules form large, polyaminated, supramolecular fibers. The surfaces of these fibers can be used as a scaffold for the condensation of silicic acid. Control over the ionic strength, dye concentration, and silicic acid saturation yielded silica fibers with a diameter of 25 nm and a single, 4 nm pore. Unexpectedly, other unusual superstructures, namely, nummulites and spherulites, are also observed depending on the ionic strength and dye concentration. Transmission and scanning electron microscopy (TEM and SEM) showed that these superstructures are formed by aligned silica fibers. Close examination of the dye scaffold prior silicification using small‐angle X‐ray scattering (SAXS), and UV/Vis spectroscopy revealed minor influence of the ionic strength and dye concentration on the morphology of the supramolecular scaffold. Total internal reflection fluorescence (TIRF) during silicification unraveled that if the reaction is kept under static conditions, only silica fibers are obtained. Experiments performed on the dye scaffold and silica superstructures evidenced that the marked structural diversity originates from the arrangement of silica/dye fibers. Under these mild conditions, external force fields can profoundly influence the morphology of the produced silica.

Chiral stacking of cyanine or porphyrin as cationic fluorescent dyes in the presence of anionic polysaccharide of hyaluronic acid

Cyanine dye or porphyrin are part of an important family of fluorophores, which have been widely used for photosensitization and optical recording materials. We compared herein the aggregation behaviors of two types of cationic dyes of cyanine or porphyrin in the presence of hyaluronic acid, which contains D-glucuronic acid as anionic helical polysaccharide. UV–Vis absorption and photoluminescence spectra of those aqueous solutions revealed that fluorescent dyes of cyanine form H- and J-aggregates in the presence of hyaluronic acid. In particular, photoluminescent quenching through the H- and J-aggregates was observed in the mixture of anionic hyaluronic acid and the cationic cyanine dyes. On the contrary, increment of the intensities of the emission was confirmed in the mixture of porphyrin-hyaluronic acid through the effective interaction between the cationic porphyrin and anionic hyaluronic acid, which was confirmed by remarkable split-Cotton effects of induced circular dichroism in the visible region, though the UV-Vis spectra of porphyrin with hyaluronic acid did not show any sign of aggregation of porphyrin itself. Further addition of hyaluronic acid resulted in the decrease of the extent of the induced circular dichroism, though photoluminescent intensity was kept without quenching. It was also confirmed that the light scattering could be detected only when the remarkable split-Cotton effects were observed. Therefore, cationic porphyrin and anionic hyaluronic acid form complex and the complex might assemble to show the light scattering, though the single molecule of porphyrin was surrounded by polysaccharides and isolated without dye-aggregation.

Mitochondria-Localized Self-Reporting Small-Molecule-Decorated Theranostic Agents for Cancer-Organelle Transporting and Imaging.

Recently, fluorescent dyes with a structure-inherent mitochondria-targeting capability have obtained great attention as single-molecule self-reporting theranostic agents to distinguish cancer cells from normal cells. However, there was little attempt using these dyes as a self-reporting ligand for cancer-targeted delivery of nanomaterials or drugs for personalized therapy. Herein, we developed a mitochondria-localized multifunctional nanodelivery system for cancer-targeted drug delivery and dual-modal imaging. First, a series of cyanine-structural small molecules with different-charged substituent groups have been screened based on their mitochondria targeting capability. Furthermore, the cyanine-structural molecule with the best mitochondria-targeting ability was decorated on iron oxide nanoparticles (IONP) for dual-modal imaging. The nanoprobes entered into the cancer cell via the organic anion transporting polypeptide (OATP) pathway and anchored on mitochondria due to the strong interaction between the negative mitochondria membrane and the lipophilic cationic cyanine dye. This work opened an avenue using small molecules with structure-inherent-targeting and self-reporting characteristics as a chemical ligand to develop cancer-targeting and subcellular-localized delivery system.

Unveiling the interaction between carbon nanodot and IR light emitting fluorescent dyes inside the confined micellar environment

In this contribution, using microwave heating of polyethylene glycol (PEG 200), we have prepared carbon nanodot (CND). It is found that in aqueous medium as well as in the micellar solutions of triblock copolymer, P123 and in anionic surface active ionic liquid (SAIL), 1-butyl-3-methylimidazolium n-octylsulfate ([C4mim][C8SO4]) the fluorescence intensity of CND gets quenched in the presence of cationic cyanine dye HITCP and cationic phenoxazine dye Nile blue (NB). Stern-Volmer constant indicates that the quenching of fluorescence intensity is more in the aqueous medium compared to P123 and [C4mim][C8SO4] i.e., (BmimOs) micelles. Time-correlated single photon counting (TCSPC) measurement reveals that the fluorescence quenching is static in nature and the quenching through Förster resonance energy transfer (FRET) process is not dominant here. Addition of both the cationic dye molecules (HITCP and NB) in CND solution generates new excited state absorption peaks in transient absorption measurement. This observation suggests that a transient species is generated through photoinduced electron transfer (PET) between the donor-acceptor pairs and this PET is responsible for the fluorescence quenching of CNDs by the dye molecules. Moreover, this electron transfer kinetics is relatively faster in bulk water compared to that inside P123 and BmimOs micelle due to the intervention of the surfactant molecules between CND and the dye molecules. Therefore, this study provides a new insight about the PET dynamics between CND and fluorescent dye molecules.

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.

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.

Spectroscopic Studies of the Interactions between a Cationic Cyanine Dye and a Synthetic Phyllosilicate: From Photophysics to Hybrid Materials.

The interaction of the cationic organic dye Astrazon orange R (AO-R) with the synthetic phyllosilicate Laponite leads to very interesting hybrid materials. Indeed, the Laponite nanoparticles modify the photophysical properties of AO-R, inducing a stabilization of its excited emissive state by preventing ultrafast isomerization. The long-lived emissive clay-dye hybrid complex can be used to develop efficient photoinitiating systems, leading to organic-inorganic hybrid crosslinked polymer materials.

The effect of the negative charge density on switchable properties of pseudoisocyanine dye

The effect of Na-montmorillonite (Mt) and synthetic stevensite (Ste) on the switchable properties of intercalated cationic cyanine dye, 1,1′-diethyl-2,2′-cyanine (pseudoisocyanine, PIC) was investigated. The switching between non-aggregated and J-type aggregated states of PIC was performed by adding and removing of dimethyl sulfoxide (DMSO) from the interlayer space. It was found that the photophysical properties of PIC after addition of DMSO are significantly influenced by the negative charge density of layered silicate. Due to this effect the J-type aggregates were after swelling with DMSO formed only in the PIC/Mt hybrid films. Photophysical response and the stability of PIC species in PIC/Mt hybrid film was tested within 20cycles of adding and removing of DMSO from the interlayer space. During these cycles the stability of PIC species was proved to be sufficient, indicating that presented experimental approach is able to enhance the use and scope of materials consisting of J-type dye molecular assemblies.

Unique solvatochromism of cyanine/saponite hybrid systems

The present study is primarily focused on the investigation of spectral properties of cationic cyanine dye (1,1′-diethyl-4, 4′-carbocyanine iodide, denoted as “NK5”) adsorbed into the structure of synthetic clay mineral (Sumecton SA, denoted as “SUM”) as a host matrix. The hybrid systems were investigated by means of absorption and fluorescence spectroscopy. Beside the solvent effect, the influence of dye/saponite ratio on the formation of specific dye species was studied in detail. It was found that used solvents have greatly affected the spectral properties of prepared hybrids. The NK5/saponite systems in ethanol and methanol were dominated by isolated dye cations. In the NK5/saponite systems in acetone and acetonitrile, the formation of higher aggregates was significantly suppressed. Moreover, the fluorescence spectra showed evidence of the formation of highly fluorescent J-aggregates. Finally, the fluorescence quantum yields of the NK5/saponite systems in various solvents were calculated. It was found that polar protic solvents as ethanol and methanol could stabilize the hybrid cyanine/saponite system with higher quantum yields as in case of used aprotic solvents.

Controlled formation of pseudoisocyanine J-aggregates in the interlayer space of synthetic saponite

In presented work dye assemblies with J-type intermolecular coupling, which are well recognized not only for their exciton transport but also for hole and electron transport properties were investigated. The use of materials consisting of J-type dye assemblies can be significantly enhanced if their photonic properties can be controlled by some external stimuli. For these reasons the switching abilities between J-type aggregated and non-aggregated states of a cationic cyanine dye, 1,1′-diethyl-2,2′-cyanine (pseudoisocyanine, PIC) intercalated in the interlayer space of synthetic saponite (Sap) were compared. The switching was performed by adding and removing of dimethyl sulfoxide (DMSO) from the interlayer space. The PIC/Sap hybrid film prepared at 70% CEC loading level has shown excellent stability within 20cycles of photophysical response after adding and removing of DMSO from the interlayer space, indicating that presented experimental approach can be useful in the future development of artificial light harvesting or semiconductor systems with controllable properties.

Multilayers and multichromic aggregates of anionic and cationic cyanine dyes

The method of formation of multilayers and multichromic 3D-J-aggregates from anionic and cationic cyanines via the sequential recharge of the metal-complexis J-aggregate surface of the anionic dye, the so-called “platform,” by the cationic dye as a result of the matrix synthesis of the J-aggregate of this dye on the surface of the platform and at the subsequent J- aggregation of anionic cyanine on a positively charged surface of the 3D-platform is considered. The conclusion that a similar method offers the possibility of selfassembly of the complex systems of aggregates from the large number of dyes distinguished by both spectral properties and by the position of the electron levels in the aggregates is made.

Multichromic J-aggregates of cyanine dyes for visible and IR range of spectrum

It is shown that on the platform of the metallocomplexis J-aggregates of anionic cyanine dyes, the “self-assembly” of J-aggregates of different cationic cyanine dyes occurs according to the matrix-synthesis method. It is concluded that the matrix synthesis of multichromic J-aggregates is promising technology for the self-assembly of wide-zone nanooptical elements for the visible and IR ranges of spectrum.

Multilayer J-aggregates of cyanine dyes

It is shown that the introduction into the aqueous solution of anionic thiamonomethinecyanine of the Mg2+ cation promotes the formation of the multilayer dye J-aggregates. It is also established that, on the J-aggregates or on the metallocomplex J-aggregates of anionic thiamonomethinecyanine, a multilayer and simultaneously multichrome system of new J-aggregate is formed due to the additional introduction of cationic cyanine dye into the solution, which absorbs light in a different region of the spectrum than anionic dye.

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.

J-aggregate formation behavior of a cationic cyanine dye on inorganic layered material

Adsorption, aggregation, and photochemical behavior of a cationic cyanine dye (5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolylcarbo-cyanine chloride (JC-1)) on an inorganic layered material were examined. JC-1 formed J-aggregates on the clay surface even at a low loading level. The structure of the J-aggregate was determined through analysis using the extended dipole model proposed by Kuhn et al. Aggregation number and slip angle of the J-aggregate on the clay surface were calculated as more than 8 molecules and 20–22°, respectively. The J-aggregate on the clay sheet exhibited high fluorescence quantum yield (0.4), thus, this complex will be promising to construct photochemical reaction systems such as artificial light harvesting systems.

Relation of molecular structure to Franck–Condon bands in the visible-light absorption spectra of symmetric cationic cyanine dyes

A Franck–Condon (FC) model is used to study the solution-phase absorbance spectra of a series of seven symmetric cyanine dyes having between 22 and 77 atoms. Electronic transition energies were obtained from routine visible-light absorbance and fluorescence emission spectra. Harmonic normal modes were computed using density functional theory (DFT) and a polarizable continuum solvent model (PCM), with frequencies corrected using measured mid-infrared spectra. The model predicts the relative energies of the two major vibronic bands to within 5% and 11%, respectively, and also reproduces structure-specific differences in vibronic band shapes. The bands themselves result from excitation of two distinct subsets of normal modes, one with frequencies between 150 and 625cm−1, and the other between 850 and 1480cm−1. Vibronic transitions excite symmetric in-plane bending of the polymethine chain, in-plane bends of the polymethine and aromatic C–H bonds, torsions and deformations of N-alkyl substituents, and in the case of the indocyanines, in-plane deformations of the indole rings. For two dyes, the model predicts vibronic coupling into symmetry-breaking torsions associated with trans–cis photoisomerization.