Electroactive films of interpolymer complexes of polyaniline with polyamidosulfonic acids: advantageous features in some possible applications

With the purpose of determining prospects of possible applications of interpolymer complexes of polyaniline (PANI) with poly(amidosulfonic acid)s, we have performed a comparative study of polyaniline films prepared by electrochemical polymerization of aniline in the presence of the polyacids distinguished by different rigidities of the polymer backbone: (1) poly(2-acrylamido-2-methyl-1-propanosulfonic acid) (flexible backbone); (2) poly-p,p′-(2,2′-disulfoacid)-diphenylen-iso-phthalamid (semi-rigid backbone); (3) poly-p,p′-(2,2′-disulfoacid)-diphelylen-tere-phthalamid (rigid backbone); and (4) a copolymer of the latter two acids with monomer feed ratio 1:1 (co-PASA). Spectroelectrochemical studies in the UV–vis–NIR range showed that PANI complexes with rigid-chain polyacids far more effectively modulate absorbance in the Vis–NIR range and can be considered as promising candidates for “smart windows” development. Due to the presence of bulky unmovable polyacid anion, PANI interpolymer complexes (particularly those with the semi-rigid-chain polyacids) possess much wider pH range of electroactivity than common PANI, which is of great importance for biosensor applications. The interpolymer complexes with flexible-chain and semi-rigid-chain polyacids exhibit good optical response to ammonia vapors at conditions of high humidity, which make them promising materials for the development of ammonia optical sensors.     

Chemical polymerization of aniline in the presence of mixtures of polymeric sulfonic acids

The template polymerization of aniline in the presence of polymeric sulfonic acids of various structures and their mixtures is studied. In the latter case, the dominant effect of a polyacid on the kinetics of aniline polymerization and the electronic structure of the resulting polyaniline complex is observed. As shown by viscometry measurements and IR studies, the intermolecular interaction between polyacids in their mixtures that leads to a change in the conformation of a flexible-chain polyacid is responsible for the dominant effect of a rigid-chain polyacid. The spectral and electrical properties of polyaniline-based interpolymer complexes are examined.     

Preparation of polyaniline in the presence of polymeric sulfonic acids mixtures: the role of intermolecular interactions between polyacids

Polyaniline (PANI) was synthesized by chemical oxidation of aniline in the presence of mixtures of water-soluble poly(sulfonic acids) of different nature. Under these conditions, the use of polyacid templates leads to the formation of interpolymer complexes of PANI and polyacid mixtures. The obtained PANI complexes were characterized by UV, visible, near IR, and Fourier transform infrared spectroscopy. It was shown that the rigidity of the polyacid backbone and the composition of a polyacid mixture affect the electronic structure of PANI complexes and the duration of the induction period of aniline oxidation. Domination of the more rigid-backbone template in the synthesis of PANI complexes with mixtures of the rigid- and flexible-backbone polyacids was observed. According to the viscometry and FTIR spectroscopic data, the reason of the domination is the existence of the intermolecular interaction between the polyacids in the mixture. In this case, duration of the induction period of aniline oxidation was between these values for pure polyacids.     

The spectroelectrochemical behavior of films of polyaniline interpolymer complexes in the near infrared spectral region

In this work, we carry out spectroelectrochemical studies of films of interpolymer complexes of polyaniline (PANI) prepared via the chemical and electrochemical template polymerization of aniline in the presence of polyamide sulfonic acids with different structures. It is shown that their spectroelectrochemical behavior in the near infrared region depends on the rigidity of the chain of the polymer sulfonic acid matrix. Electrodeposited films of PANI complexes with a rigid-chain polyacid exhibit a more intense absorption in the near infrared region (1000–2200 nm) and a less intense absorption in the absorption region of localized polarons (around 750 nm) in comparison with complexes with a flexible-chain polyacid. The comparison of the dependence of absorption in the near infrared region on potential with the cyclic voltammetry curves suggests that the chromophores responsible for this absorption are radical cations in nature. In the spectra of the films of chemically synthesized PANI complexes with a flexible-chain polyacid, during a long-term cycling in the region of potentials of the first redox stage of PANI, the absorption in the near infrared region which corresponds to delocalized polarons is also formed. This is apparently attributed to the intensification of the intermolecular interactions under the conformational fluctuations that accompany the change in the degree of oxidation of the film during cyclic voltammetry.     

The influence of polyacid nature on poly(3,4-ethylenedioxythiophene) electrosynthesis and its spectroelectrochemical properties

The present study is aimed to elucidate main structural features of polymeric sulfonic acids (the rigidity of main chain, the distance between sulfonic groups on the chain, the hydrophobicity of main chain or side fragments) on the course of 3,4-ethylenedioxythiophene (EDOT) electropolymerization and electronic and chemical structure of the poly(3,4-ethylenedioxythiophene) (PEDOT) films obtained. The films were prepared by electrochemical polymerization in cyclic voltammetry, potentiostatic, and galvanostatic regimes in aqueous solutions of different polyacids in the absence of supporting electrolyte. The effect of the chemical structure of polyacid on the course and rate of PEDOT synthesis was traced by electrochemical and in situ UV-Vis spectroscopic methods. It was shown that the highest rate of EDOT electropolymerization is achieved in the presence of flexible-chain polyacid having hydrophobic fragments (groups) in its structure, followed by hydrophobic rigid-chain polyacids. The lowest rate was observed in the presence of hydrophilic flexible-chain polyacid. The electronic and chemical structure of the PEDOT films obtained was studied by in situ UV-Vis-NIR and Raman spectroelectrochemistry. The films prepared in the presence of rigid-chain polyacids at high anodic potentials demonstrate decreased content of bipolaronic fragments in their structure, while PEDOT complexes with flexible-chain polyacids are very much like conventional polymer prepared in non-aqueous medium. The results are discussed in terms of conformational state (ability to form coils and thus concentrate the monomer) of different polyacids in aqueous solution and hydrophobic interactions between the polyacids and EDOT.     

Copper(II) complexing with 2′,2′-diethylheptanohydrazide

Acid-base properties of 2′,2′-diethylheptanohydrazide (DEHH) and its complex formation with copper(II) ions in water-isopropanol solutions were studied. Cationic complexes with [Cu²⁺] : [DEHH] ratios of 1 : 1 and 1 : 2 were found to be formed in weak acid media, and an uncharged complex with a [Cu²⁺] : [DEHH] ratio of 1 : 2 was found to be formed in a basic medium. log K _st values were determined. The data obtained were compared with the stability constants of copper(II) 2′,2′-diethylbenzohydrazide complexes.     

Synthesis, characterization and catalytic oxidation of tetrahydrofuran with 16-membered pentaazabis(macrocyclic) copper(II) complexes; {[Cu([16]aneN5)]2R}4+ (R = aromatic nitrogen–nitrogen linkers)

New square-planar bis(macrocyclic)dicopper(II) complexes containing phenylene bridges between 16-membered pentaaza macrocyclic subunits have been synthesized via in-situ one pot template condensation reaction (IOPTCR) of aromatic nitrogen-nitrogen linker (R = 1,4-phenylenediamine; benzidine; 4,4′-diaminodiphenylmethane; 4,4′-diaminodiphenylether; 4,4′-diaminodiphenylsulfone), formaldehyde, bis(1,3-diaminopropane)copper(II) perchlorate and 1,3-dibromopropane in a 1:4:2:2 molar ratio results in the formation of new series of binuclear copper(II) complexes; 1-phenyl- (1); 1,1′-phenyl- (2); 1,1′-diphenylmethan- (3); 1,1′-diphenylether- (4); 1,1′-diphenylsulfone- (5) bis(1,3,7,11,15-pentaazacyclohexadecane)copper(II)), {[Cu([16]aneN₅)]₂R}(ClO₄)₄″. The formation of the macrocyclic framework and the mode of bonding of the complexes have been confirmed by data obtained from elemental analyses, UV-visible, FT-IR, ¹H-NMR, electronic spectral studies, conductivity and magnetic susceptibility measurements. These bis(macrocyclic) complexes catalyzed efficiently the selective oxidation of tetrahydrofuran into tetrahydrofuran-2-one and a small amount of tetrahydrofuran-2-ol and 4-hydroxybutyraldehyde using dil. H₂O₂ as the oxidant.     

Interpolymer complexes of copolymers of vinyl ether of diethylene glycol with poly(acrylic acid)

 The complex formation reactions of poly(vinyl ether of diethylene glycol) as well as vinyl ether of diethylene glycol–vinyl butyl ether copolymers with poly(acrylic acid) have been studied in aqueous and alcohol solutions. The formation of interpolymer complexes which were stabilized by hydrogen bonds was shown. The effects of molecular weight of poly(acrylic acid) and the nature of the nonionic polymer on the composition and stability of interpolymer complexes were clarified. The critical pH values of complexation were determined for different systems with various molecular weights and hydrophobic–hydrophilic balances. The stability of the interpolymer complexes formed in aqueous and alcohol solutions with respect to dimethylformamide addition was evaluated. The role of hydrophobic interactions and the presence of active groups on stability of the interpolymer complexes is discussed. Received: 23 July 2001 Accepted: 27 September 2001     

Synthesis,spectroscopic characterization,thermal, and photostability studies of 2-(2′-hydroxy-5′-phenyl)-5-aminobenzotriazole complexes

Three Mn(II), Co(II), and Cu(II) new transition metal complexes of the fluorescence dye: 2-(2′-hydroxy-5′-phenyl)-5-aminobenzotriazole/PBT derived from o-aminophenol and m-phenylenediamine have been synthesized. The structural interpretations were confirmed from elemental analyses, magnetic susceptibility and molar conductivity, as well as from mass, IR, UV–Vis spectral studies. From the analytical, spectroscopic, and thermal data, the stoichiometry of the mentioned complexes was found to be 1:2 (metal:ligand). The molar conductance data revealed that all the metal chelates are non-electrolytes and the chloride ions exist inside the coordination sphere. The thermal stabilities of these complexes were studied by thermogravimetric (TG/DTG) and the decomposition steps of these three complexes are investigated. The kinetic parameters such as the energy of activation (E*), pre-exponential factor (A), activation entropy (ΔS*), activation enthalpy (ΔH*), and free energy of activation (ΔG*) have been reported. Photostability of phenyl benzotriazole as fluorescence dye and their metal complexes doped in polymethyl methacrylate/PMMA were exposed to UV–Vis radiation and the change in the absorption spectra was achieved at different times during irradiation period.     

Complexes of poly-5-vinyltetrazoles with weak polybases

Formation of interpolymer complexes of poly(5-vinyltetrazole) and poly(5-izopropenyltetrazole) with poly(acrylamide), poly(ethylene oxide), poly(1-vinylpyrrolidone), and poly(1-vinyl-1,2,4-triazole) was investigated by potentiometry and viscometry. The reduced activity of tetrazol-containing polyacids in reaction with poly(1-vinylpyrrolidone) from polyacrylic polyacids was explained by steric hindrances at the expense of bulky tetrazolic rings. There is a strong system of hydrogen bonds in the poly(5-vinyltetrazole) solution that leads to decreasing of its activity in the complexation in comparison with poly(5-izopropenyltetrazole). Hydrophobic interactions between methyl groups of poly(5-izopropenyltetrazole) lead to additional stabilization of the complexes at low degrees of ionization and to fast destruction of them at ionization degrees corresponding to destruction of the compact conformation of poly(5-izopropenyltetrazole) (α = 0.2–0.4). Interaction of poly(5-vinyltetrazole) with poly(1-vinyl-1,2,4-triazole) at elevated pH leads to an interpolymer complex stabilized by donor–acceptor interactions between the π-systems of tetrazolate anions and triazole rings. © 1996 John Wiley & Sons, Inc.     

Synthesis and characterization of polyaniline nanoparticles in phosphonic acid amphiphile aqueous micellar solutions for waterborne corrosion protection coatings

Polyaniline (PANI) dispersions consisting of 270 to 380 nm sized particles were prepared by oxidation with ammonium peroxydisulfate (APS) in n‐decylphosphonic acid (DPA) micellar solutions. The green dispersions do not undergo macroscopic precipitation for more than a year. The synthesized DPA doped PANI exhibited enhanced electrical conductivity (3.6 S cm^?1 ) compared with DPA‐PANI (2.3 x 10 ^{? 4} S cm ^{? 1}) prepared by postsynthesis treatment of the PANI‐base with DPA. It was shown that through protonation with decylphosphonic acid, polyaniline showed a significantly enhanced solubility in common organic solvents like chloroform, xylene, etc. The synthesized PANI was characterized by intrinsic viscosity, solubility, FT‐IR , conductivity, SEM , and TGA measurements. The wide‐angle X ‐ray diffraction study revealed the appearance of a peak located at low angles (d = 29.4 – 35.3 Å) suggesting the formation of layered structure of PANI backbone separated by long alkyl side chains of DPA. The anticorrosive performance of the bilayer coatings composed of a bottom layer of DPA doped polyaniline covered with a polyvinyl butyral topcoat, have been demonstrated for steel exposed to neutral saline solutions. It was found that the inhibitive properties of DPA dopant provides further protection to the base metal through smart release when damage is produced on the surface of the coating. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1606–1616     

Cobalt(II) complexes of various thiosemicarbazones of 4-aminoantipyrine: syntheses,spectral, thermal and antimicrobial studies

An interesting series of cobalt(II) complexes of the new ligands: 4[N-(benzalidene)amino]antipyrinethiosemicarbazone (BAAPTS), 4[N-(2′-hydroxy-benzalidene)amino]antipyrinethiosemicarbazone (HBAAPTS) and 4[N-(2′-hydroxy-1′-naphthalidene)amino]antipyrinethiosemicarbazone (HNAAPTS) were synthesized by reaction with Co(II) salts in ethanol. The general stoichiometry of the complexes was found to be [CoX₂(H₂O)(L)] and [Co(L)₂](ClO₄)₂, where X = Cl, NO₃, NCS or CH₃COO and L = BAAPTS, HBAAPTS or HNAAPTS. The complexes were characterized by elemental analysis, molar conductivity measurement, molecular weight determination, magnetic moments at room temperature, infrared and electronic spectra. All the thiosemicarbazones behave as neutral tridentate (N, N, S) donor ligands. The conductivity measurements in PhNO₂ solution indicated that the chloro, nitrato, thiocyanato and acetate complexes are essentially non-electrolytes, while the perchlorate complexes are 1:2 electrolytes. Thermogravimetric studies were performed for some representative complexes and the decomposition mechanism proposed. Antibacterial and antifungal properties of the ligands and their cobalt(II) complexes have also been examined and it has been observed that the complexes are more potent bactericides than the ligand.     

Complexation of 4′-nitrobenzo-15-crown-5 with Mg<Superscript>2+</Superscript>, Ca<Superscript>2+</Superscript>, Sr<Superscript>2+</Superscript> and Ba<Superscript>2+</Superscript> metal cations in acetonitrile-methanol binary solutions

The complex formation reactions between Mg²⁺, Ca²⁺, Sr²⁺ and Ba²⁺ metal cations with macrocyclic ligand, 4′-nitrobenzo-15C5, were studied in acetonitrile (AN)-methanol (MeOH) binary mixtures at different temperatures using conductometric method. The results show that 4′-nitrobenzo-15C5 forms 1:1 [ML] complexes with Mg²⁺, Ca²⁺ and Sr²⁺ metal cations in solutions. But in the case of Ba²⁺ cation a 1:2 [ML₂] complex is formed in these solvent systems. The stability of the complexes is sensitive to the solvent composition and a non-linear behavior was observed for variation of logK _f of the complexes versus the composition of the binary mixed solvents. The stability constants of complexes decrease suddenly with increasing the concentration of methanol in this binary system. The values of thermodynamic parameters (ΔH _c^° and ΔS _c^°) for formation of (4′-nitrobenzo-15C5.Mg)²⁺, (4′-nitrobenzo-15C5.Ca)²⁺ and (4′-nitrobenzo-15C5.Sr)²⁺ complexes were obtained from temperature dependence of the stability constants and the results show that these parameters are affected by the nature and composition of the mixed solvents. A non-linear behavior is observed between the ΔS _c^° and the composition of the mixed solvents.     

Some novel tetradentate Schiff base complexes VO(IV) and Cu(II) involving fluorinated heterocyclic β-diketones and polymethylene diamines of varying chain length

The present article describes the synthesis, spectral, coordination and thermal aspects of N,N′-polymethylene bis(1-phenyl-3-methyl-4-trifluoroacetylimino-2-pyrazoline-5-ol)oxovanadium(IV) or copper(II) Schiff base complexes with alkyl backbones ranging from two to four carbons have been characterized on the basis of elemental analysis, magnetic moments, molar conductivity measurements, spectra (FTIR, ESR, UV-Visible, MS), VPO and thermal studies. The vapour pressure osmometry (VPO) and mass spectral studies indicate that the complexes are monomeric. An ESR study of all these complexes of VO(IV) and Cu(II) are consistent with the square pyramidal and square planar geometries of these metal ions, respectively. In addition, the kinetics and thermodynamic parameters for the different thermal decomposition steps of the complexes have been studied employing Horowitz-Metzger and Freemen-Carroll methods.     

Mass spectrometric identification and characterization of antimony complexes with ribose-containing biomolecules and an RNA oligomer

Mass spectrometric techniques have been used to study the interaction of inorganic Sb(V) with biomolecules containing a ribose or deoxyribose moiety. Electrospray (ES) mass spectra of reaction mixtures containing inorganic Sb(V) and one of several biomolecules (adenosine, cytidine, guanosine, uridine, adenosine-5′-monophosphate, adenosine-3′,5′-cyclic monophosphate, ribose, or 2′-deoxyadenosine) afforded high-mass antimony-containing ions corresponding to Sb(V)–biomolecule complexes of stoichiometry 1:1, 1:2, or 1:3. The complexes were characterized by collision-induced dissociation (CID) tandem mass spectrometry (MS) using ion-trap multistage MS. The CID results revealed that Sb(V) binds to the ribose or deoxyribose moiety. Structures are proposed for the Sb–biomolecule complexes. Analysis of the reaction mixtures by reversed-phase chromatography coupled on-line to either inductively coupled plasma (ICP) MS or ES–MS showed that in solution Sb(V) forms complexes with all the analyzed biomolecules with vicinal cis hydroxyl groups. Evidence (from size-exclusion chromatography ICP–MS and direct infusion ES–MS) of complexation of Sb(V) with an RNA oligomer, but not with a DNA oligomer, supports the suggestion that the presence of vicinal cis hydroxyl groups is critical for complexation to occur. This is the first direct evidence of complexation of Sb(V) with RNA. Results obtained by studying the effect of changing reaction conditions, i.e. pH, reaction time, and Sb/biomolecule molar ratio, on the extent of Sb–biomolecule formation suggest the reaction may be of physiological importance. Selected reaction monitoring (SRM) and precursor-ion-scanning tandem MS were investigated to determine their potential to detect trace levels of the Sb–biomolecule complexes in biological samples. Application of SRM MS–MS in combination with high-performance liquid chromatography enabled successful detection of an Sb–adenosine complex that had been spiked into a complex biological matrix (liver homogenate).Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Ternary Complexes of La(III), Ce(III), Pr(III) or Er(III) with Adenosine 5′-mono, 5′-di,and 5′-triphosphate as Primary Ligands and some Biologically Important Zwitterionic Buffers as Secondary Ligands

Equilibrium constant measurements have been performed potentiometrically at (25±0.1) °C and an ionic strength I=0.1 mol⋅dm⁻³ KNO₃ for the interaction of La(III), Ce(III), Pr(III) and Er(III) with the purine nucleotides adenosine 5′-mono, 5′-di, and 5′-triphosphate and with the biologically relevant secondary ligand zwitterionic buffers 3-(cyclohexyl amino)-1-propanesulfonic acid (CAPS), 3-(cyclohexylamino)-2-hydroxy-1-propane sulfonic acid (CAPSO), N-tris(hydroxymethyl)methyl-3-aminopropanesulfonic acid (TAPS), 3-[N-bis(hydroxyethyl)amino]-2-hydroxypropanesulfonic acid (DIPSO), N,N-bis(2-hydroxyethyl)glycine (BICINE), and N-(2-acetamido)-2-iminodiacetic acid (ADA) in a 1:1:1 ratio. The formation of various 1:1:1 normal and protonated mixed-ligand complex species was inferred from the potentiometric pH titration curves. The experimental conditions were selected such that self-association of the purine nucleotides and their complexes was negligibly small; that is, the monomeric normal and protonated ternary complexes were studied. Initial estimates of the formation constants of the resulting species and the acid dissociation constants of adenosine 5′-mono-, 5′-di-, and 5′-triphosphate and the zwitterionic buffer secondary ligands were refined with the Superquade computer program. In some Ln(III) mixed-ligand systems, interligand interactions between the coordinating ligands, possibly involving H-bond formation, have been found to be the most important factors in deciding the stability of the mixed-ligand complexes in solutions. The thermodynamic ΔG° values of the monomeric normal and protonated ternary complexes were calculated and discussed.     

Photophysical investigations of interpolymer interactions in solutions of a pyrene substituted poly(acrylic acid), poly(vinyl amine), poly(1-aminoacrylic acid), and poly(1-acetylaminoacrylic acid)

Photophysical properties of the pyrene chromophore covalently bound to poly(acrylic acid) were used to investigate the interactions of a pyrene substituted poly(acrylic acid) (1) with poly(vinyl amine hydrochloride) (PVAm), poly(1-aminoacrylic acid) (PDA), and poly(1-acetylaminoacrylic acid) (PADA) in aqueous solutions. A number of photophysical parameters were obtained from fluorescence emission and excitation spectra, the deconvolution of decay curves for pyrene monomer, and excited state complex fluorescence and the quenching of pyrene monomer fluorescence by nitromethane in polymer solutions. These photophysical parameters were considered to reflect the inter- and intrapolymer interactions in solutions of 1 , PVAm, PDA, and PADA. The formation of interpolymer complexes between 1 and PVAm was noticed at low (< 4) as well as high (> 8) values, whereas PDA and 1 formed interpolymer complexes at low pH only. No interpolymer complex formation was detected in solutions of 1 and PADA under low or high pH conditions. The structures of interpolymer complexes formed between 1 and PVAm under low and high pH conditions were found to be determined by the conformation of 1 . There were significant differences in the interpolymer interactions of 1 and PDA in comparison to those of 1 and PVAm; in particular, the fluorescence from the excited state complex was enhanced in solutions of 1 and PVAm but quenched in solutions of 1 and PDA. The investigations of terpolymer solutions of 1 , PVAm, and PADA indicated that the nature of interpolymer complexes formed in terpolymer solutions was determined by Coulombic interactions of the amino and carboxylic group containing polymers.     

Study of cis-trans equilibrium of oxacarbocyanine dyes in solution and in a complex with DNA

Cis-trans equilibrium for a number of meso-substituted oxacarbocyanine dyes, 3,3′-diethyloxacarbocyanine iodide (K1), 3,3′-diethyl-9-methyloxacarbocyanine iodide (K2), 3,3′-dimethyl-9-ethyloxacarbocyanine iodide (K3), 3,3′,9-triethyl-6,6′-dimethoxyoxacarbocyanine iodide (K4), and 3,3′,9-triethyl-5,5′-dimethyloxacarbocyanine iodide (K5), has been studied in solutions and in a complex with DNA by spectral and fluorescent methods. A shift of the cis-trans isomer equilibrium toward the formation of the trans-isomer was observed in the presence of DNA, which determined in many respects the spectral effects observed upon the complexation of the oxacarbocyanine dyes. A steep rise of fluorescence (due to binding of the trans-isomer) in a complex with DNA is favorable for using oxacarbocyanine dyes to determine DNA.