Interaction of chromophores in dissimilar associates of cationic and anionic polymethine dyes in water

A strong interaction between chromophores of cationic and anionic components was found based on the analysis of electronic absorption spectra of aqueous solutions of mixtures of cationic indopolycarbocyanines with anionic cyanines. Strong dissimilar 1∶1 associates are formed. Association constants were estimated spectrophotometrically. The main factors determining the degree of interaction of chromophores were revealed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 950–955, May, 1997.     

Magnetically assisted removal and separation of cationic dyes from aqueous solution by magnetic nanocomposite hydrogels

Magnetic poly(acrylic acid‐acrylamide‐butyl methacrylate) (P(AAB)) nanocomposite hydrogels were prepared and used as adsorbents for removal and separation of cationic dyes from aqueous solution. These magnetic P(AAB) nanocomposite hydrogels were characterized by scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). It was found that these magnetic P(AAB) nanocomposite hydrogels had magnetic responsive characters. The dynamic swelling, removal, and separation of cationic dye, crystal violet (CV), and basic magenta (BM) by these magnetic nanocomposite hydrogels were studied. The adsorption capacity and isotherm studies of cationic dyes onto magnetic P(AAB) nanocomposite hydrogels have been evaluated. The magnetic P(AAB) nanocomposite hydrogels containing Fe₃O₄ particles can be easily manipulated in magnetic field for removal and separation of cationic dyes from aqueous solution. Adsorption process agreed very well with the Langmuir and Freundlich models. Copyright © 2010 John Wiley & Sons, Ltd.     

季铵盐类阳离子单体的合成工艺研究进展

对季铵盐类阳离子单体的合成工艺及结构改性研究进展进行了综述。基于季铵盐类阳离子单体的基本结构与性质,从合成反应基本历程及代表性制备工艺方法出发,介绍了二烯丙基季铵盐类、丙烯酰胺烷基季铵盐类和丙烯酰胺烷基季铵盐类三类最为重要的季铵盐阳离子单体的合成、聚合及结构改性最新研究进展,指出了已有研究工作的特色与不足,并认为开发高质量丙烯酰胺烷基季铵盐类单体及聚合物产品以及高纯度质量稳定的阳离子单体制备新工艺是今后应努力的方向。     

Analysis of the Interactions of Polyvinylpyrrolidone with Conventional Anionic and Dimeric Anionic Surfactant

Classical physical method has been applied in the present study of interaction between water soluble polymer with anionic dimeric and conventional anionic surfactants. Micellization activity of carboxylate-based anionic dimeric (CAD) as well as sodium dodecyl sulfate (SDS) surfactants in the presence of nonionic polymer, that is, polyvinylpyrrolidone (PVP), has been studied through conductometric and surface tensiometric measurements. From these methods the critical aggregation concentrations (CACs), critical micelle concentrations (CMCs), and the effective degree of counterion binding (β) were determined. For the evaluation of behavior of CAD toward the PVP various thermodynamic properties viz. standard Gibbs energy of micellization, standard enthalpy, and entropy of micellization of CAD/PVP mixed system have also been estimated and discussed. The results exhibit that anionic dimeric surfactant interacts strongly with PVP as compared to conventional surfactant.     

The interaction of anionic azo dyes with hen egg-white lysozyme: 2

In continuation of our preceding study, this report describes pH and ionic strength dependences of the binding constants of six anionic azo dyes to lysozyme, the competitive binding of the dyes with the substrate analogues of lysozyme and the change in the circular dichroism of lysozyme by the dye binding. The binding constants were obtained from the difference spectra of visible absorption. With an increase in pH from 5.0 to 7.0 the constants for the dyes (1st of the two modes of the binding of a dye named D3) are reduced. The increase in ionic strength from 0.1 to 0.2 also reduces the values of the constant. Competitive binding was found between D3 and the analogues, but not for the other dyes. The change in the circular dichroism due to the electronic perturbation of tryptophyl residues in lysozyme was found. From these evidences, Lys 33 in lysozyme is pinpointed as the most credible binding site for the dyes (1st mode binding of D3). An unspecified location near the subsiteB in lysozyme is addressed for 2nd mode binding of D3.     

Star-shaped polymers by living cationic polymerization. VII. Amphiphilic graft polymers of vinyl ethers with hydroxyl groups: Synthesis and host–guest interaction

Amphiphilic graft polymers of vinyl ethers (VEs) ( 6 ) where each branch consists of a hydrophilic polyalcohol and a hydrophobic poly(alkyl vinyl ether) segment were prepared on the basis of living cationic polymerization, and their properties and functions were compared with the corresponding amphiphilic star-shaped polymers. In toluene at ?15°C, the HI/ZnI₂-initiated living block polymer 2 of an ester-containing VE (CH₂? CHOCH₂CH₂OCOCH₃) and isobutyl VE (IBVE) was terminated with the diethyl 2-(vinyloxy)ethylmalonate anion [ 3 ; ^ΦC(COOEt)₂CH₂CH₂OCH ? CH₂] ( 2/3 = 1/2 mole ratio) to give a macromonomer ( 4 ), H[CH₂CH(OCH₂CH₂OCOCH₃)] _m-[CH₂CH(OiBu)]_n? C(COOEt)₂CH₂CH₂OCH ? CH₂ (m = 5, n = 15; M?_n = 2600, M?_w/M?_n = 1.13, 1.10 vinyl groups/chain). Subsequently, 4 was homopolymerized with HI/ZnI₂ in toluene at ?15°C. In 3 h, 85% of 4 was consumed and a graft polymer ( 5 ) was obtained [M?_w = 15000, DP_n (for 4 ) = 6]. The apparent M?_w (10,900) of 5 by size-exclusion chromatography (SEC) is smaller than that by light scattering as well as that (18,300) by SEC of the corresponding linear polymer with the almost same molecular weight, indicating the formation of a multi-branched structure. Hydrolysis of the pendant esters in 5 gave the amphiphilic graft polymer 6 where each branch consists of a hydrophilic polyalcohol and a hydrophobic poly(IBVE) segment. The graft polymer 6 was found to interact specifically with small organic molecules (guests) with polar functional groups, and 6 differed in solubility and host-guest interaction from the corresponding star-shaped polymer. © 1993 John Wiley & Sons, Inc.     

Interaction of the low-molecular weight salts with cationic polyelectrolytes

The interaction of several mono-, di-, and trivalent anions with cationic polyelectrolytes having different contents in N,N-dimethyl-2-hydroxypropylen ammonium chloride units (polymer A) or tertiary amine N-atoms and PEG (polymer PEGA) in the main chain was studied by viscosimetric and conductometric measurements. Both methods have shown a stronger interaction for tri- and bi- than for univalent counterions. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 2571–2581, 1997     

The interaction of anionic azo dyes with hen egg-white lysozyme: 1

The interactions between seven anionic azo dyes and hen egg-white lysozyme were investigated by means of visible absorption spectroscopic and lytic activity measurements. The dyes, for which no report on the interaction has appeared so far, were bound with lysozyme to different extents as a result of the differences in their chemical structures. Although most of the dyes formed 11 complex with lysozyme, two of them behaved differently. From the measurements of the absorption, lytic inhibition toward cell walls and competitive binding with substrate analogues, it was concluded that a major binding site of these dyes on lysozyme is a charged lysine residue in the vicinity of the subsitesD, E andF, and, in the case of a dye that forms 21 complex with lysozyme, and additional binding site is in the vicinity of the subsite B.     

Interaction of surfactant with antistatic polymer thin layers

Thin layers made from three kinds of hydrophilic polymer were coated onto poly(ethylene terephthalate)(PET) fibers to study the interaction of an anionic surfactant, sodiumn-dodecyl benzenesulfonate, with the polymer layers. The coated layers include a) poly(vinyl alcohol) (PVA) crosslinked with glutaraldehyde [nonionic], b) crosslinked, sulfated PVA [anionic], and c) polyethyleneimine crosslinked with poly(ethyleneglycol diglycidylether) [cationic]. All of these coatings were found to reduce the electrostatic charging of the PET cloths, indicating that they were effectively coated with the hydrophilic polymers. The PET cloth coated with the thin layers was immersed in the aqueous solution of surfactant at 40°C for different durations and the electrostatic voltage as well as the weight change were determined after drying. When the cloth coated with the nonionic or the anionic layer was brought into contact with the surfactant, neither the electrostatic voltage nor the weight of PET changed. On the contrary, immersion in the surfactant solution brought about an increase in both the electrostatic voltage and the weight for the PET coated with the cationic layer. This suggested that the surfactant molecules were bound to the cationic layer, in contrast to the nonionic and the anionic layer. It was concluded that the binding was due to ion complexing between the cationic groups in the polymeric layer and the sulfate groups in the surfactant molecules.     

Regiospecific cationic polymerization of spiroorthoesters with different cyclic ether ring sizes

Spiroorthoesters (SOEs), cis‐2,3‐tetramethylene‐1,4,6‐trioxaspiro[4,5]decane ( I ) and cis‐2,3‐tetramethylene‐1,4,6‐trioxaspiro[4,6]undecane ( II ), with different cyclic ether ring sizes were synthesized, and their stereostructure and steric energy were determined. With steric‐hindrance‐sensitized 9‐phenyl‐9,10‐dihydro‐anthracen‐10‐ylium cation as an initiator, I and II underwent regiospecific polymerization to yield trans form of stereoregular poly(ether esters)—poly(trans‐2‐oxycyclohexyl pentanoate) (? [trans‐2‐OCHP]_n? ) ( III ) and poly(trans‐2‐oxycyclohexyl hexanoate) (? [trans‐2‐OCHH]_n? ) ( V ), respectively. With SnCl₄ as another initiator, I and II underwent regiospecific polymerization through different mechanisms to afford cis form poly(cis‐2‐oxycyclohexyl pentanoate) (? [cis‐2‐OCHP]_n? ) ( IV ) and trans form (? [trans‐2‐OCHH]_n? ) ( VI ) stereoregular poly(ether esters). The polymerization mechanisms of SOEs proceeded in the regiospecific manner were determined by the relationship among the sterostructures of SOEs and its subsequently formed polymers, the steric energy of monomers, and the free energy difference in the transition state of reaction. Owing to the conversion of cis substitution at C‐2 and C‐3 in I or II to the trans form during polymerization, polymers III , V , and VI exhibited a higher volume of expansion during polymerization than IV , which showed high volume shrinkage. Group contributions of divalent trans‐ and cis‐1.2‐cyclohexyl groups were derived and confirmed by measuring the densities of the corresponding stereoregular polymers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Surface-active properties of new cationic gemini surfactants with cyclic spacer

Three cationic gemini surface active compounds of the type (1r,4r)-1,4-dialkyl-1,4-dimethy-l-piperazine-1,4-diium bromide (Ia, Ib, and Ic), were synthesized. They were characterized using elemental analysis and ¹H-NMR spectra. Their surface-active properties were measured in aqueous solutions with different concentrations at different temperatures (25, 40, and 55°C). Various surface measurements of these gemini surfactants, (compared to the conventional one, 1-Dodecyl-1-methylpiperidinium bromide (a)) were estimated, specifically critical micelle concentration (CMC), effectiveness (π_CMC), efficiency (P_C20) as well as maximum surface excess (Γ_max) and minimum surface area (A_min). The measurements of the gemini compounds gave low CMC, high efficiency in reducing the surface tension, and intense adsorption at air/water interface. These surfactants have lower Krafft points and thus better solubility. Thermodynamic data, free energy, entropy, and enthalpy changes (ΔG°, ΔS°, and ΔH°) for micellization at the air/water interface and also for adsorption in the bulk of surface-active solutions were calculated.     

Electrospun TiO2 nanofibers coated with polydopamine for enhanced sunlight-driven photocatalytic degradation of cationic dyes

Controlled polydopamine (PDA)-coated TiO₂ composite nanofibers (NFs) were successfully fabricated via a facile electrospinning process and exposing TiO₂ NFs into a slightly alkaline dopamine solution. Chemical composition, structural morphology, and photocatalytic degradation property of as-prepared TiO₂ NFs and PDA-coated TiO₂ composite NFs were characterized by Fourier transfer infrared, X-ray photoelectron spectra, transmission electron microscopy, UV-vis diffuse reflectance spectra, and photocatalytic degradation experiments. The results indicated that the core-shell TiO₂@PDA composite NFs were successfully prepared and the thickness of PDA shell was highly controlled within several nanometers. And obtained TiO₂@PDA composite NFs exhibited improved photocatalytic performance after PDA coating, which is attributed to the photosensitization of PDA shell. Moreover, with increased pH values of initial solution, both absorption capacity in the dark and photocatalytic performance of TiO₂@PDA composite NFs showed significant improvement. Additionally, the obtained composite NFs showed different degrees of enhancement in photocatalytic performance based on different dyes, which is related to the “bait” effect of PDA shell. Comparing with anionic dyes, TiO₂@PDA composite NFs tended to adsorb and degrade more cationic dye molecules. It is anticipated that the fabricated composite NFs with controlled core-shell structure have great potential to be applied for organic pollutants removal, especially cationic dyes.     

Interaction of cationic chlorin photosensitizers with non-ionic surfactant Tween 80

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Synthesis of end-functionalized polystyrenes with organosilicon end-capping reagents via living cationic polymerization

The end-functionalization of living polymers with bases (methanol, benzylamine, diethyl sodiomalonate, and sodium methoxide) and organosilicon compounds [X ? Si(CH₃)₃;X ? : CH₂?C(CH₃)COO? , CH₃COO? , CH₂?CHCH₂? , C₆H₅? ] was investigated in the living cationic polymerization of styrene initiated with the 1-phenylethyl chloride/SnCl₄/nBu₄NCl system in CH₂Cl₂ at ?15°C. The four bases and C₆H₅SiMe₃, independent of their structures, were apparently incapable of reacting with the living end and invariably led to polystyrenes with the ω-end chlorine [～ ～ ～ CH₂CH(Ph)Cl] originated from the initiating system. The number-average end-functionality (F?_n) of the chloride, determined by ¹H-NMR, was close to unity (F?_n > 0.9). The presence of chlorine in the polymer was also confirmed by elemental analysis. In contrast, the quenching by the trimethylsilyl compounds with X = methacryloxy, acetoxy, and allyl gave ω-end-functionalized polystyrenes with the corresponding terminal groups (X) for which the F?_n values were close to unity (F?_n > 0.9). The effects of the structure of silyl compounds on end-capping are also discussed. © 1994 John Wiley & Sons, Inc.     

Interaction of catalase with cationic hydrogels: Influence of pH,kinetics of process and isotherms of adsorption

The adsorption interaction of catalase Penicillium vitale with cationic polymer hydrogels prepared from the vinyl ether of monoethanolamine was studied at various pHs of phosphate buffer solution, interaction times and enzyme concentrations. The hydrogels behaved as anion exchange swellable gel adsorbents. The formation of stable polymer–protein complexes with high enzymatic activity has been shown. The dependence of the interaction degree of protein macromolecules on swelling coefficients of gel has been found. The isotherms of protein adsorption indicate the thermodynamical irreversibility of the process. Copyright © 1999 John Wiley & Sons, Ltd.     

Mixing Behavior of Cationic Hydrotropes with Anionic Surfactant Sodium Dodecyl Sulfate

Mixing behavior of anionic surfactant sodium dodecyl sulfate (SDS) with cationic hydrotropes aniline hydrochloride (AH), o-toluidine hydrochloride (o-TH), and p-toluidine hydrochloride (p-TH) have been studied using conductivity at different temperatures. Critical micelle concentration for different mixing mole fractions, their ideal values, and different interaction parameters have been estimated. All the parameters show nonideal behavior with synergistic interactions. Thermodynamic parameters are also calculated for these systems.     

Synthesis and properties of oxetane‐based polysiloxanes used for cationic UV curing coatings

The polysiloxanes end‐capped with oxetane group (PSiO‐H and PSiO‐L) were synthesized via hydrosilylation reaction based on α,ω‐dihydrogen‐terminated polydimethylsiloxanes with a higher (0.23%, PDSi‐H) and lower (0.12%, PDSi‐L) hydrogen amount. The molecular structures were characterized by FT‐IR and ¹H NMR spectroscopy. The polysiloxanes were added into a commercial oxetane‐based resin, 3,3′‐(oxydi(methylene)) bis(3‐ethyloxetane) (DOX), as an additive to prepare a series of cationic UV curable formulations. The photo‐DSC results showed that the maximum photopolymerization rate decreased while the oxetane conversion increased with the polysiloxane content increasing. The surface hydrophobic property of cured films was improved having the water contact angles of 97° and 99° compared with 82° of the cured DOX film with only 1 wt% PSiOs, respectively. The dynamic mechanical thermal analysis results showed that both the storage modulus on the rubbery plateau region and the glass transition temperature decreased with increasing PSiO‐H loading. Moreover, the decrease became more obvious as PSiO‐L was added instead of PSiO‐H due to its lower concentration of oxetane group. The thermal stability of cured films was enhanced by the addition of PSiOs from the thermogravimetric analysis. And the DOX/PSiO‐H film possessed higher thermal degradation temperatures than DOX/PSiO‐L film. Copyright © 2011 John Wiley & Sons, Ltd.     

TD-DFT analysis of the excitation of H-dimers of cationic dyes in an aqueous solution using functionals without additional dispersion correction

This work is a development and extension of the previous one (DOI: 10.1039/d3cp00882g ). Here, H-dimers of acridine (acridine orange—AO and proflavine—PF), thiazine (methylene blue—MB and thionine—TH), and oxazine (brilliant cresyl blue—BCB and Nile blue—NB) dyes were modeled using hybrid functionals with a large proportion of exact Hartree–Fock exchange and long-range correction. It turned out that nine functionals (LC-ωHPBE, M06HF, M052X, M062X, M08HX, M11, MN15, SOGGA11X, and ωB97XD) reliably stabilize these molecular aggregates in both the ground and excited states. In addition, these functionals ensure that the conditions for transition moments (M(dimer) ≈ $\sqrt{2}$M(monomer) from strong coupling theory for H-aggregates) and absorption maxima (λ_max(dimer) < λ_max(monomer) from Kasha exciton theory) are met. The S₂ excited state stabilizes the H-dimers more strongly than the ground state, while the S₁ state stabilizes even more than S₂. This is due to the large overlap between the corresponding molecular orbitals (LUMO > HOMO−1 > HOMO). When calculating the vibronic absorption spectra, the best agreement with the experiment for AO₂, PF₂, and NB₂ showed the M08HX functional, and M11—for MB₂ and BCB₂. For dye monomers, these functionals gave the worst agreement, and MN15 demonstrated the closest similarity to the experiment. Vibronic absorption spectra for AO₂, MB₂, BCB₂, and NB₂ were calculated for the first time. The exciton splitting is calculated, which for MB₂ is in good agreement with the experimental value.