Polyelectrolyte complexes. II. Specific aspects of the formation of polycation/dye/polyanion complexes

We report on the formation of the polycation/dye/polyanion (PC/D/PA) complexes by the interaction between nonstoichiometric polycation/dye (PC/D) complexes with polyanions. Polycations differed in their content of the (N,N‐dimethyl‐2‐hydroxypropylene ammonium chloride) units in the main chain. Poly(sodium acrylate) (NaPA), poly(sodium 2‐acrylamido‐2‐methylpropane sulfonate) (NaPAMPS) and poly(sodium styrenesulfonate) (NaPSS) were used as polyanions. Crystal Ponceau 6R (CP6R) and Ponceau 4R (P4R) with two or three sulfonic groups were used as anionic dyes. The interaction between nonstoichiometric PC/D complexes and polyanions was followed by UV‐VIS spectroscopy, viscometry, and conductometry measurements. Formation of PC/D/PA complexes takes place mainly by the electrostatic interaction between the polyanion and the free positive charges of the nonstoichiometric PC/D complex. The stoichiometry and the stability of the tricomponent complexes depended on the polycation structure, the structure and molecular weight of polyanion, the dye structure, and the P/D molar ratio. A high amount of the dye was excluded from the complex before the end point when a branched polycation was used. The higher the solubility of the dye the lower the stability of the PC/D/PA complexes. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 409–418, 1999     

Polyelectrolyte complexes. V. Solid‐state properties of some polycation/azo dye complexes controlled by the dye structure

The solid‐state properties of some polycation/azo dye complexes according to the dye structure were studied in this work. One polycation contained about 95 mol % N,N‐dimethyl‐2‐hydroxypropyleneammonium chloride units in the backbone (PCA₅), and eight azo dyes, different in either the number of sulfonic groups or their distribution, were used as opposite components. The selected azo dyes were as Crystal Scarlet, Congo Red, Crocein Scarlet MOO, Ponceau SS, Amaranth, Ponceau S, Direct Blue 1, and Direct Red 80. Information on the compensation degree of the oppositely charges was obtained by the elemental analysis of the solid‐state polycation/dye complexes (the experimental contents of chlorine, nitrogen, and sulfur were compared with the calculated values). Differential scanning calorimetry was employed to probe the strength of the intermolecular interactions in the PCA₅/dye complexes. Wide‐angle X‐ray diffraction was used to assess the supramolecular order of the solid‐state complexes. The physical properties of the PCA₅/azo dye complexes (the complex stoichiometry, glass‐transition temperature, decomposition temperature, and degree of supramolecular order) were influenced mainly by the dye structure but also by the polycation concentration and the presence of NaCl. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 264–272, 2003     

Transformation of textile dyes by white-rot fungus Trametes versicolor

We have investigated transformation of eight industrial dyes by a whiterot fungus, Trametes versicolor. The fungus was found to decolorize Reactive Golden Yellow R, Procion Red, Reactive Violet 5, Reactive Blue 28, and Ponceau Red 4R at an initial dye concentration of 80 ppm within 72 h of incubation, whereas it took 5 d to completely decolorize Reactive Black 5 (40 ppm). However, it did not significantly decolorize Reactive Red 152 and Novatic Blue BC S/D. During decolorization in liquid medium, laccase and manganese-independent peroxidase (MiP) activities were detected in culture filtrate of T. versicolor. Dye-decolorizing activity of the culture was found to be associated with H₂O₂-dependent activity of the culture filtrate. Furthermore, dye-decolorizing activity of the culture filtrate was not influenced by Mn²⁺ or veratryl alcohol, thus suggesting a role of extracellular MiP in decolorization of synthetic dyes by T. versicolor.     

Synthesis and characterization of graphene and ordered mesoporous TiO2 as electrocatalyst for the determination of azo colorants

Ordered mesoporous TiO₂, synthesized by soft template method, coupled with graphene was used to modify a carbon paste electrode. The graphene layer was very thin and the mesoporous TiO₂ particles were nano-scale, as confirmed by scanning electron microscopy and transmission electron microscopy. Graphene and mesoporous TiO₂ displayed remarkable enhancement effect and greatly increased the oxidation signals of two azo colorants, i.e., Ponceau 4R and Allura Red. The influence of electrolyte, scan rate, amount of graphene and mesoporous TiO₂, accumulation potential, and time on the signal enhancement of Ponceau 4R and Allura Red was discussed, and therefore, a novel and sensitive electrochemical method was developed for the detection of Ponceau 4R and Allura Red. The linear range was wider than two order of magnitude for both of Ponceau 4R and Allura Red. The limit of detection for Ponceau 4R and Allura Red was 1.35 and 0.34 nM, respectively. Finally, this method was successfully applied in soft drink and sausage samples, which was confirmed by high-performance liquid chromatography technique.     

New Synthesis of N,N‐Disubstituted (4‐Aminophenyl)diazenyl‐1,3,4‐thiadiazole,and Mesogenic Study and Molecular Modeling of Its H‐Bonded Complexes with a Series of m‐Alkoxybenzoic Acid Derivatives

A new N,N‐disubstituted (4‐aminophenyl)diazenyl‐1,3,4‐thiadiazole, an azo dye, was synthesized from the reaction of the 1‐decanoyl‐4‐phenylpiperazine in acetone, in situ, with the diazonium salt prepared from 1,3,4‐thiadiazol‐2‐amine and NaNO₂ in H₃PO₄. The azo dye was found to form complexes with a series of m‐alkoxybenzoic acid by intermolecular H‐bonding. The mesogenic behavior of the complexes were investigated by polarizing optical microscopy and differential scanning calorimetry. A study of the representing complex by powder X‐ray diffraction and molecular modeling was further undertaken to locate the H‐bonding position.     

Kinetic studies of photoelectrocatalytic degradation of Ponceau 6R dye with ammonium persulfate

Kinetic degradation of Ponceau 6R dye using oxidation with ammonium persulfate (APS) as oxidant, and catalyzed by electro, photo, and photo-electro at pH 1.0 was investigated. Ammonium persulfate (APS) proved to be a better oxidant of dye with photoelectrocatalytic degradation (PECD). The influence of various pH of the solution on the efficiency of degradation of dye was investigated. The results were observed that the dye decolorization was enhanced using PECD at pH 2.0. The rate of degradation of dye with APS followed pseudo-first order kinetics in the dye concentration. Also, it can be seen that increasing the concentration of oxidant (APS) led to a higher rate of dye decolorization.     

A new fast swelling poly[DAPB-co-DMAAm-co-AASS] superabsorbent hydrogel for removal of anionic dyes from water

The objective of this research is to utilize a new poly[N,N-diallyl pyrrolidinium bromide-co-N,Ndimethyl acrylamide-co-acrylic acid sodium salt]superabsorbent hydrogel（SAH）for the removal of two anionic dyes,e.g.,Reactive Red 5B（RR5B）and Reactive Orange M2R（ROM2R）,from water.The SAH was characterized by swelling in water,FTIR,TGA and SEM.The SAH DDA6showed good swelling property and thermal stability.We have also investigated the parameters affecting dye adsorption such as pH,adsorbent dose,adsorption rate and initial dye concentration.The experimental data were also analyzed by applying the well known Langmuir and Freundlich isotherm models.     

Application of poly(N-isopropylacrylamide) with pendent β-cyclodextrin to separation of a guest substance in an aqueous solution

Poly(N-isopropylacrylamide) with pendent β-cyclodextrin (PNI-PAAm-CD) was prepared by copolymerization of acryloyl-β-CD and NIPAAm. During the temperature-induced phase separation of an aqueous solution of PNIPAAm-CD, Toluidine Blue dye in the solution was separated into the precipitate of PNIPAAm-CD by way of inclusion complex formation.     

The effect of cation size on ion pairing of methyl orange dye with tetraalkylammonium and benzyltrialkylammonium ions in aqueous solution

Formation constants have been measured by a solvent distribution method for the ion pairing of an arene sulfonate, methyl orange dye, with two series of quaternary ammonium ions: R₄N⁺(R=Et,n-Pr,n-Bu, andn-Pent) and C₆H₅CH₂R₃N⁺ (R=Me, Et,n-Pr,n-Bu,n-Pent, andn-Hex). Ion pairing increases dramatically as the length of the R group increases beyond butyl. Using a hard-sphere model for contact ion pairs, it is estimated that coulombic attraction contributes about –kT to the binding free energy and decreases slightly with increasing size of R₄N⁺. Other factors related to solvation effects, of which cosphere overlap predominates, contribute from –2kT to –7kT of binding energy. Plots of logK for association as a function of cation size show an inflection with decreasing slope between R=propyl and R=butyl. Possible causes for the inflection are considered.     

Solvatochromic Parameters and Preferential Solvation Behavior for Binary Mixtures of 1,3-Dialkylimidazolium Ionic Liquids with Water

Binary mixtures of 1,3-dialkylimidazolium based ionic liquids (ILs) and water were selected as solvent systems to investigate the solute-solvent and solvent-solvent interactions on the preferential solvation of solvatochromic indicators at 25℃. Empirical solvatochromic parameters, dipolarity/polarizability (π^*), hydrogen-bond donor acidity (α), hydrogen-bond acceptor basicity (β), and Reichardt's polarity parameters (E_T^N) were measured from the ultraviolet-visible spectral shifts of 4-nitroaniline, 4-nitroanisole, and Reichardt's dye. The solvent properties of the IL-water mixtures were found to be influenced by IL type and IL mole fraction (x_IL). All these studied systems showed the non-ideal behavior. The maximum deviation to ideality for the solvatochromic parameters can be obtained in the xIL range from 0.1 to 0.3. For most of the binary mixtures, the π^* values showed the synergistic effects instead of the E_T^N, α and β values. The observed synergy extent was dependent on the studied systems, such as the dye indicator and IL type. A preferential solvation model was utilized to gather information on the molecular interactions in the mixtures. The dye indicator was preferentially solvated on the following trend: IL >IL-water complex >water.     

Color Characteristics of Aqueous Solutions of Synthetic Food Dyes

The color characteristics of aqueous solutions of synthetic food dyes Azo Rubine, tartrazine, Indigo Carmine, Ponceau 4R, Sunset Yellow, and Brilliant Blue were studied. A formula is proposed for determining the hue of dye solutions.     

Four‐Membered Heterometallacyclic d0 and d1 Complexes of Group 4 Metallocenes with Amidato Ligands

A study of the coordination chemistry of different amidato ligands [(R)N?C(Ph)O] (R=Ph, 2,6‐diisopropylphenyl (Dipp)) at Group 4 metallocenes is presented. The heterometallacyclic complexes [Cp₂M(Cl){κ²‐N,O‐(R)N?C(Ph)O}] M=Zr, R=Dipp ( 1 a ), Ph ( 1 b ); M=Hf, R=Ph ( 2 )) were synthesized by reaction of [Cp₂MCl₂] with the corresponding deprotonated amides. Complex 1 a was also prepared by direct deprotonation of the amide with Schwartz reagent [Cp₂Zr(H)Cl]. Salt metathesis reaction of [Cp₂Zr(H)Cl] with deprotonated amide [(Dipp)N?C(Ph)O] gave the zirconocene hydrido complex [Cp₂M(H){κ²‐N,O‐(Dipp)N?C(Ph)O}] ( 3 ). Reaction of 1 a with Mg did not result in the desired Zr(III) complex but in formation of Mg complex [(py)₃Mg(Cl) {κ²‐N,O‐(Dipp)N?C(Ph)O}] ( 4 ; py=pyridine). The paramagnetic complexes [Cp′₂Ti{κ²‐N,O‐(R)N?C(Ph)O}] (Cp′=Cp, R=Ph ( 7 a ); Cp′=Cp, R=Dipp ( 7 b ); Cp′=Cp*, R=Ph ( 8 )) were prepared by the reaction of the known titanocene alkyne complexes [Cp₂′Ti(η²‐Me₃SiC₂SiMe₃)] (Cp′=Cp ( 5 ), Cp′=Cp* ( 6 )) with the corresponding amides. Complexes 1 a , 2 , 3 , 4 , 7 a , 7 b , and 8 were characterized by X‐ray crystallography. The structure and bonding of complexes 7 a and 8 were also characterized by EPR spectroscopy.     

XAD-2 HPTLC Method of Identification and Determination of Some Synthetic Food Colourings

Abstract

An HPTLC method for identification and determination of 12 synthetic dyes (Amaranth, Allura red, Brilliant black BN, Brilliant blue E, Carmoisine, Erythrosine, Indigotine, Patent blue V, Ponceau 4R, Quinoline yellow, Sunset yellow, Tartazine) has been developed. Amberlite XAD-2 was used as a stationary phase for column chromatography. Elution was performed with various acidified alcohols (i-propanol, n-propanol, n-butanol) and recoveries between 81.5 - 100.2% were obtained. The low limit of detection is in the range of 4 – 10 ng. The method was tested on commercial products as: carbonated soda, candies, chewing gum, identical natural flavours, etc.     

Synthesis and Properties of a New Two-photon-absorbed Material Heasps

Abstract

A new dye Trans-4-[p-(N-hydroxyethyl-N-ethyiamino)styryl]-N-methylpyridinium p-toluene sulfonate (HEASPS) was synthesized, and the two-photon absorption (TPA), TPA-induced frequency up-conversion emission, and two-photon pumped (TPP) frequency up-converted lasing properties of this new dye were experimentally studied. This new dye has a moderate TPA cross-section of\sigma₂ = 4.7 × 10^?48 cm⁴ .s/photon at 1064nm, but exhibits a high lasing efficiency. The net conversion efficiency from the absorbed 1064 nm pump pulse energy to the 626 nm up-converted lasing energy is 18.2% at the pump energy level of 1.9 mJ.     

Rhodamines with a Chloronicotinic Acid Fragment for Live Cell Superresolution STED Microscopy**

Formylation of 2,6-dichloro-5-R-nicotinic acids at C-4 followed by condensation with 3-hydroxy-N,N-dimethylaniline gave analogs of the popular TAMRA fluorescent dye with a 2,6-dichloro-5-R-nicotinic acid residues (R=H, F). The following reaction with thioglycolic acid is selective, involves only one chlorine atom at the carbon between pyridine nitrogen and the carboxylic acid group and affords new rhodamine dyes absorbing at 564/ 573 nm and emitting at 584/ 597 nm (R=H/ F, in aq. PBS). Conjugates of the dyes with “small molecules” provided specific labeling (covalent and non-covalent) of organelles as well as of components of the cytoskeleton in living cells and were combined with fluorescent probes prepared from 610CP and SiR dyes and applied in two-color STED microscopy with a 775 nm STED laser.     

Relaxivity Study and X-ray Structure of Gd(III)-diethylenetriamine-N,N′,N′-triacetic-N,N″-bis(benzylamide). A Potential MRI Contrast Agent

The new bis(amide) derivatives of DTPA (diethylenetriamine-N,N,N′,N″,N″-pentaacetic acid), diethylenetriamine-N,N′,N″-triacetic-N,N″-bis(benzylamide) (DTPA-BBA) have been synthesized. The crystal structure of gadolinium(III) complex of DTPA-BBA ([Gd(DTPA-BBA)]) has been determined by X-ray crystallography: C₂₈H₅₂GdN₅O₁₇, M_w = 889 g mol^?1, space group $ {\rm P}\bar 1 $ (#2) (triclinic), a = 12.645(4), b=14.125(8), c = 12.623(4) Å, α = 111.60(3), β = 114.79(3), γ = 88.39(4)°, V = 1881(1) ų, Z = 2, D_x = 1.569 g/cm³, λ(Mo Kα) =0.71069 Å, μ = 18.44 cm^?1, final R = 0.047, R_w = 0.046 for 3755 independent observed reflections at 23 °C. The coordination sphere of Gd(III) comprises three amine nitrogens, two amide oxygens, three carboxylic acid oxygens, and one water. The relaxivity of Gd(III) complex was determined to be R1 = 4.08(4) and R2 = 6.06(5) dm³ mmol^?1 s^?1 at pH = 7.0, 20 MHz, and 37(1) °C. Additionally, the R1 relaxivity for Gd(III) chelate was found to be invariant with respect to pH changes over the range of 2-10. This indicates that a constant inner-sphere hydration number is associated with the [Gd(DTPA-BBA)] complex. Hence the high stability of the complex is demonstrated.     

Computational Photochemistry of the Azobenzene Scaffold of Sudan I and Orange II Dyes: Excited‐State Proton Transfer and Deactivation via Conical Intersections

We employed the complete active space self‐consistent field (CASSCF) and its multistate second‐order perturbation (MS‐CASPT2) methods to explore the photochemical mechanism of 2‐hydroxyazobenzene, the molecular scaffold of Sudan I and Orange II dyes. It was found that the excited‐state intramolecular proton transfer (ESIPT) along the bright diabatic ¹ππ* state is barrierless and ultrafast. Along this diabatic ¹ππ* relaxation path, the system can jump to the dark ¹nπ* state via the ¹ππ*/¹nπ* crossing point. However, ESIPT in this dark state is largely inhibited owing to a sizeable barrier. We also found two deactivation channels that decay ¹ππ* keto and ¹nπ* enol species to the ground state via two energetically accessible S₁/S₀ conical intersections. Finally, we encountered an interesting phenomenon in the excited‐state hydrogen‐bonding strength: it is reinforced in the ¹ππ* state, whereas it is reduced in the ¹nπ* state. The present work sets the stage for understanding the photophysics and photochemistry of Sudan I–IV, Orange II, Ponceau 2R, Ponceau 4R, and azo violet.     

THE PHOTOCHEMICAL PROPERTIES OF FLUOROALUMINUM PHTHALOCYANINE

Abstract Fluoride is known to inhibit the photodynamic activity of aluminum phthalocyanine in a variety of biological systems. In order to gain insight into this phenomenon, the effect of fluoride on the photophysical properties of free and albumin-bound chloroaluminum phthalocyanine sulfonate (AlPcS_n.) were studied. The association constant of NaF with AlPcS_n, in aqueous solution was measured as 500 ± 20 M^?1. This binding affects the photophysical properties of the dye: the absorption bands in the visible range are blue-shifted by 6–8 nm, and this effect is mirrored in the fluorescence emission spectrum. Human serum albumin significantly quenched the dye fluorescence independent of the presence of fluoride ion. The transient absorption spectrum of the excited dye triplet is unchanged by NaF, but the quantum yield for its generation is increased by 50%, with no decrease in its lifetime. Formation of fluoroaluminum phthalocyanine complexes was also observed in tetrabutylammonium fluoride-assisted solutions in wet acetonitrile. The fluoro-AlPcS_n, complex is a better photosensitizer for generation of singlet oxygen than the original dye-hydroxyl ion complex, as confirmed using the imidazole-N,N-dimethyl-4-nitrosoaniline method. On the other band, the fluoro-AlPcS_n. complex exhibits an intense inhibitory effect on photohemolysis of red blood cells (RBC) even after the cells are washed to remove free dye and fluoride prior to irradiation, indicating that once the dye is attached to the cellular site, the fluoride ligand is no longer prone to displacement (by hydroxyl ion, for example). Nonetheless, it is clear from the spectroscopic data that the new fluoro complex is an efficient sensitizer for photo-oxidation. Therefore, the reduced photodynamic action of the fluoro-AlPcS_n. complex on RBC (Ben-Hur et al., Photochem. Photobiol. 58 , 351–355, 1993) may result from a lowering of the efficiency of interaction of the fluorodye complex with sensitive cell target moieties.     

Spectral Sensitization of Photoconductivity of Poly(<Emphasis Type="Italic">N</Emphasis>-epoxypropylcarbazole) and Benzaldehyde Diphenylhydrazones by Ternary Complexes of Triphenylmethane Dyes

Spectral sensitization of photoconductivity of poly(N-epoxypropylcarbazole) and benzaldehyde diphenylhydrazones by chlorides and ternary complexes of triphenylmethane dyes was studied. It was shown that an increase in the sensitization activity of a triphenylmethane dye upon replacement of chloride anion in its molecule with a complex anion containing metal was due to a change in the electron-acceptor ability of the dye molecule.__________Translated from Khimiya Vysokikh Energii, Vol. 39, No. 5, 2005, pp. 362–366.Original Russian Text Copyright © 2005 by Kobotaeva, Sirotkina, Mikubaeva.     

Highly-sensitive electrochemical sensing platforms for food colourants based on the property-tuning of porous carbon

It is very challenging to develop highly-sensitive analytical platforms for toxic synthetic colourants that widely added in food samples. Herein, a series of porous carbon (PC) was prepared using CaCO₃ nanoparticles (nano-CaCO₃) as the hard template and starch as the carbon precursor. Characterizations of scanning electron microscopy and transmission electron microscopy indicated that the morphology and porous structure were controlled by the weight ratio of starch and nano-CaCO₃. The electrochemical behaviours of four kinds of widely-used food colourants, Sunset yellow, Tartrazine, Ponceau 4R and Allura red, were studied. On the surface of PC samples, the oxidation signals of colourants enhanced obviously, and more importantly, the signal enhancement abilities of PC were also dependent on the starch/nano-CaCO₃ weight ratio. The greatly-increased electron transfer ability and accumulation efficiency were the main reason for the enhanced signals of colourants, as confirmed by electrochemical impedance spectroscopy and chronocoulometry. The prepared PC-2 sample by 1:1 starch/nano-CaCO₃ weight ratio was more active for the oxidation of food colourtants, and increased the signals by 89.4-fold, 79.3-fold, 47.3-fold and 50.7-fold for Sunset yellow, Tartrazine, Ponceau 4R and Allura red. As a result, a highly-sensitive electrochemical sensing platform was developed, and the detection limits were 1.4, 3.5, 2.1 and 1.7 μg L⁻¹ for Sunset yellow, Tartrazine, Ponceau 4R and Allura red. The practical application of this new sensing platform was demonstrated using drink samples, and the detected results consisted with the values that obtained by high-performance liquid chromatography.