Quinoline Dyes Research Articles

Synthesis, spectroscopic, and structural studies of substituent effect on the solvatochromic, tautomeric, and halochromic behavior of 2-methylated arylazoquinoline dyes along with DFT calculations

Six methylated heteroarylazo quinoline dyes with different electron-withdrawing/donating substituents, namely 5-(4-substituted arylazo)-8-hydroxy-2-methyl quinoline dyes, were synthesized by coupling reaction and their chemical structures were elucidated by conventional spectroscopic methods. The photophysical properties of the dyes were examined and systematically compared in a range of solvents of various solvatochromic parameters and at various pH values through UV–Vis spectroscopy. 2-methylated arylazoquinoline dye (the unsubstituted dye) was prepared and chosen for comparison purposes. The dyes show different chromic behavior including tautomerism, solvatochromism, ionochromism, and halochromism. The chromic and azo/hydrazone tautomeric properties of the dyes were found to depend on the substituent nature, solvent polarity/polarizability, and the acidity/basicity of the solvent environment. The Kamlet-Abboud-Taft, Katritzky, and Catalán linear solvation energy relationships (LSER) were used to correlate the dye spectral data. The acid-base equilibria between neutral and anionic forms of the dyes were studied in buffer solutions in a range of pH 1.0–13.0 and the ionization constants,pKa, were determined. Finally, the DFT calculations on the studied compounds provide an overall supportive and complementary picture of the spectral measurements of representative structure of the azo model.

Absorption, fluorescence, and two-photon excitation ability of 5-phenyl-13-arylisoindolo[2,1-a]quinolines prepared by one-pot reaction of ring-closing metathesis and 1,3-dipolar cycloaddition

Substituted 5-phenyl-13-aryl-isoindolo[2,1-a]quinoline dyes that exhibit two-photon absorption up to 375 GM have been synthesized via ruthenium-catalyzed ring-closing metathesis in tandem with a 1,3-dipolar cycloaddition reaction.

Synthesis, characterization, spectroscopic properties and computational studies of some new azo dyes derived from 5-chloro-8-hydroxy quinoline

Purpose The purpose of this study, 3-aminopyridine, 8-aminoquinoline and some new synthesized 2-aminobenzothiazoles were diazotized with nitrosyl sulfuric acid and subsequently coupled with 5-chloro-8-hydroxy quinoline to synthesize the corresponding heteroarylazo dyes 6–13. Design/methodology/approach The structures of dyes were characterized by mass, Fourier transform infra red, 1H proton nuclear magnetic resonance and ultra violet-visible spectroscopic techniques. Absorption spectra of the dyes were measured in acetic acid, ethanol, chloroform, acetonitrile, dimethyl formamide and dimethyl sulfoxide and correlated with the nature of the solvents and substituents. The effects of varying pH on the absorption wavelengths of the azo dyes were also studied. In addition, the acidity constants (pKa) of the dyes were determined using the spectrophotometric method in an ethanol-water mixture (80:20, v/v) at 20–23°C. Besides, density functional theory (DFT) calculations were carried out to compare the energies of proposed azo and hydrazone tautomers of the dyes. Findings The results showed that the withdrawing chloro groups on the diazo moiety have significant influence (red shift) on the electron absorption spectra of these dyes. In addition, introducing electron withdrawing chloro groups into the benzothiazoles moiety increased the acidic character of dyes. Originality/value The synthesized 7-hetroarylazo-5-chloro-8-hydroxy quinoline dyes are new members in the 8-hydroxyquinoline azo dyes family, where very few details regarding the synthesis of such dyes are reported before in the literature. They are unique in terms of synthesis, spectral properties and DFT calculations.

Trifluoromethyl Substituted Derivatives of Pyrazoles as Materials for Photovoltaic and Electroluminescent Applications

New 6-CF3-1H-pyrazolo[3,4-b]quinolines with a methyl and/or phenyl group attached to the pyrazole core (Molx (x = 1, 2, 3, 4)) were synthesized and characterized in terms of their optoelectronic applications: photovoltaic and electroluminescence. The fluorescence emissions of the investigated phenyl-decorated pyrazoloquinolines is caused by the photoinduced charge transfer p process occurring between the phenyl substituent and the pyrazoloquinoline core, while 1,3-dimethyl-6-CF3-1H-pyrazolo[3,4-b]quinoline exhibits an π,π*-type emission. The number of phenyls and their substitution positions modulate both emission properties and HOMO energy levels. Next, the bulk heterojunction BHJ solar cells based on 1H-pyrazolo[3,4-b] quinoline derivatives with architecture ITO/PEDOT:PSS/PDT + Molx/Al were fabricated. The organic active layer was a blend of Molx and poly(3-decylthiophene-2,5-diyl). The complex refractive index and the layer thickness of the organic solar cells were determined using a spectroscopic ellipsometer Woollam M2000 (J.A. Woollam Co., Inc., Lincoln, NE, USA) and CompleteEASE software. For solar devices with the best value of power efficiency of approximately 0.38%, the thickness of the active layer (Mol3 + PDT) was 111 nm, with a short-circuit current density of JSC = 32.81 μA/cm2 and an open–circuit voltage of VOC = 0.78 V. Finally, we demonstrated double-layer light-emitting diodes with an organic active layer (Molx + PVK) and an electron transporting material layer, ETM (2-[3,5-bis(4-phenyl-2-quinolyl)phenyl]-4-phenylquinoline (Tris-Q). Bright bluish-green light originating from the active layer was observed in the double-layer device, ITO/PEDOT:PSS/active layer/ETM/Ca/A. The active layer was a mixture of PV-doped 1H-pyrazolo[3, 4-b]quinoline dyes. An OLED device was constructed by employing Molx as an emitter, which gave a deep bluish-green emission with the spectra range of 481–506 nm. The best value of the maximum brightness at approximately 1436.0 cd/m2 was achieved for a diode based on Mol3 (1-phenyl-3-phenyl-6-CF3-1H-pyrazolo[3,4-b]quinoline) and [R1 = Ph, R3 = Ph and R6 = CF3]. The current efficiency was up to 1.26 cd/A at 506 nm with a CIE of 0.007, 0.692.

Absorption, Fluorescence, and Two-Photon Excitation Ability of 5-Phenylisolidolo[2,1-a]quinolines.

We report on the absorption, fluorescence, and two-photon excitation spectra of a series of 5-phenylisoindolo[2,1-a]quinoline dyes. Depending on the substituents, we observed increasing two-photon absorption cross sections, with values up to 56 GM@973 nm, which are similar to those of the enhanced green fluorescent protein and fluorescein, common fluorescent chromophores.

Highly Selective and Efficient Synthesis of 7-Aminoquinolines and Their Applications as Golgi-Localized Probes.

Quinoline derivatives have extensively been used for both pharmaceutical agents and bioimaging. However, typical synthesis of quinoline derivatives is generally through strong acid/base-catalyzed or metal-catalyzed methods at high temperatures. Here we report a catalyst-free synthesis of 2,4-disubstituted 7-aminoquinolines with high selectivity and good yields via the introduction of a trifluoromethyl group. It is discovered that quinolines containing both amino and trifluoromethyl groups exhibit strong intramolecular charge-transfer fluorescence with large Stokes shifts. We further applied the obtained quinolines to live-cell imaging and found that some of the derivatives can target specifically Golgi apparatus in various cell lines (HeLa, U2OS, and 4T1 cells) in vitro and the colocalization with commercial Golgi marker is retained during the mitosis in HeLa cells. Moreover, the quinoline dyes can also be used for Golgi apparatus imaging with two-photon fluorescence microscopy. These results provide new insights into developing low cost Golgi-localized probes.

Synthesis of luminescent polymers in the UV light region from dimethacrylate monomer using novel quinoline dyes

ABSTRACTThis study aims at thermal and morphological features, as well as the degree of conversion these luminescent polymers obtained using a dimethacrylate monomer, and quinoline dyes as photoinitiator. The photoinitiators provide a fluorescent propriety to the final polymer. Thermal properties such as thermal stability, steps of mass loss, and glass transition are obtained by thermogravimetry‐differential thermal analysis and derivative thermogravimetric and differential scanning calorimetry. Using the mid‐infrared spectroscopy, it is possible to calculate the degree of conversion/rate of polymerization; the data indicate that the quinoline derivatives could be used as photoinitiators in lower concentration (0.1%) resulting in solid rigid polymers with higher conversion (74.24, 71.81, 66.36, and 61.09%). The morphological characteristics of polymers are analyzed by scanning electronic microscopy. Finally, solid ultraviolet–visible (UV–vis) analysis shows a bathochromic shift, due to the stabilization of the molecules in the solid state, compared to liquid UV–vis analysis. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47461.

Tautomerism, solvatochromism, preferential solvation, and density functional study of some heteroarylazo dyes

Photophysical characteristics of four synthesized heteroarylazo quinoline dyes were studied in various media with different solvatochromic parameters. Preferential solvation of the compounds was investigated in some mixed binary solvents. It was established that in the media with basic nature, only one tautomeric form and corresponding anion exist, which the latter is the main species. In the polar protic solvent, both the azo and hydrazone forms are present. The linear solvation energy relationships (LSER) were used to correlate the absorption spectral data. Using the absorption and emission spectra, the ground and the excited states dipole moments of the compounds were evaluated. The dyes were observed to show halochromism, dichromism, and anion affinity as well. The acid-base equilibria between neutral and anionic forms of the compounds were studied in buffer solutions of varying pH and ionization constants for these dyes were determined. The dyes exhibit positive linear dichroic behavior in the anisotropic medium, which indicate that all the absorption bands are due to the π − π∗ transitions. In order to analysis of the spectral behavior, time-dependent density functional theory (TD-DFT) calculations were performed.

Facile Synthesis and Photophysical Characterization of New Quinoline Dyes.

This paper describes the synthesis of new quinoline derivatives, molecules that has been long interest in the organic and medicinal chemistry. Through the Multicomponent Reaction (MCR), an important tool in modern synthetic methodology, that generate products with good structural complexity, in addition to economy of atoms and selectivity, we provide easy access to the preparation of quinoline derivatives. The reactions were promoted by niobium pentachloride, as a Lewis acid. Subsequently, the synthesis of new aminoquinoline derivatives with good yields was performed using Pd/C and hydrazine. The photophysical investigations of quinoline derivatives show the substituent effect on the optical properties characterization was done by absorption and photoluminescence measurements with quantum yields of up to 83%, the presence of the amino group at position 6 at the quinoline backbone was crucial for obtaining these increased quantum yields. Results show that these molecules may have potential use for a variety of applications and mainly attracts attention because of its wide potential of applicability in optoelectronic devices.

Fate of commercial disperse dyes in sediments

Kinetics of disappearance of seven different disperse dyes were determined in compacted sediments at room temperature. The commercial dyes (in dispersed solid form) were representative of nitroazo, anthraquinone, and quinoline structures that are widely used. Reaction rates were found to be first order over at least two half-lives and were different for the three groups of dyes. Half-lives were on the order of hours, days and months for the nitroazobenzene, aminoanthraquinone, and quinoline dyes, respectively. Stability of the latter is consistent with detection of a quinoline dye in treatment plant sludge and in sediment from a water body receiving treated effluent. The azobenzene dyes are degraded by cleavage of the azo group to give anilines and ring-substituted phenylenediamines from the diazo component of the molecule. Products from the other portion (coupling component) of the molecule are unidentified, as yet, but are expected to be N,N-disubstituted phenylenediamines. Products of the anthraquinone dyes were unidentified, except for the case of a nitrated dye on which the nitro group was reduced.

Interaction of lanthanide shift reagents with alkyltosylates of heterocyclic bases and tosylates of cyanine dyes

The interaction of alkyltosylates of derivatives of pyridine, quinoline, benzothiazole, benzimidazole, and cyanine dyes with the lanthanide shift reagent Eu(fod)3 is studied. The structure of the salt cations is related to their ability to interact with the LSR. Results of a calculation of the structure of the adducts of heterocyclic alkyltosylates with the LSR are presented.

Disparate skin allergenicity of 2 quinoline dyes.

Disparate skin allergenicity of 2 quinoline dyes.

Topo-optical reactions and polarization optical analysis of human lymphocytes.

The latent birefringence of lymphocyte membranes of various species may readily be studied and analysed by various topo-optical reactions. The membranes of glutaraldehyde-fixed and PBS-washed lymphocytes show continuous birefringence with thiazine- and quinoline dyes. According to polarization optical analysis thiazine dye-stained cells are radially positive, whereas quinoline dye-stained cells are radially negative spherites, i.e. thiazine dye molecules are in a perpendicular, quinoline dye molecules in a parallel orientation relative to the membrane surface. These findings suggest that in lymphocyte membranes glycoproteins are primarily responsible for the topo-optical reactions. The actual conformational state of the glycoprotein components is a decisive factor not only in dye binding but also in the orientation of dye molecules. Heparin treatment directs attention to an important interaction between heparin and membrane glycoproteins. With the aid of the critical electrolyte concentration (CEC) technique we were able to demonstrate an ultrastructural differences between human erythrocyte and human lymphocyte membranes. After this procedure the birefringence of erythrocyte membranes was lost, whereas that of lymphocyte membranes did not change. There were no differences between the topo-optical reactions of T and B lymphocytes.