Polymeric Schiff Base Research Articles

Polymeric Schiff bases as low-voltage redox centers for sodium-ion batteries.

The redox entity comprising two Schiff base groups attached to a phenyl ring (-N=CH-Ar-HC=N-) is reported to be active for sodium-ion storage (Ar=aromatic group). Electroactive polymeric Schiff bases were produced by reaction between non-conjugated aliphatic or conjugated aromatic diamine block with terephthalaldehyde unit. Crystalline polymeric Schiff bases are able to electrochemically store more than one sodium atom per azomethine group at potentials between 0 and 1.5 V versus Na(+)/Na. The redox potential can be tuned through conjugation of the polymeric chain and by electron injection from donor substituents in the aromatic rings. Reversible capacities of up to 350 mA h g(-1) are achieved when the carbon mixture is optimized with Ketjen Black. Interestingly, the "reverse" configuration (-CH=N-Ar-N=HC-) is not electrochemically active, though isoelectronic.

Polymeric Schiff Bases as Low‐Voltage Redox Centers for Sodium‐Ion Batteries

AbstractThe redox entity comprising two Schiff base groups attached to a phenyl ring (NCHArHCN) is reported to be active for sodium‐ion storage (Ar=aromatic group). Electroactive polymeric Schiff bases were produced by reaction between non‐conjugated aliphatic or conjugated aromatic diamine block with terephthalaldehyde unit. Crystalline polymeric Schiff bases are able to electrochemically store more than one sodium atom per azomethine group at potentials between 0 and 1.5 V versus Na+/Na. The redox potential can be tuned through conjugation of the polymeric chain and by electron injection from donor substituents in the aromatic rings. Reversible capacities of up to 350 mA h g−1 are achieved when the carbon mixture is optimized with Ketjen Black. Interestingly, the “reverse” configuration (CHNArNHC) is not electrochemically active, though isoelectronic.

Uptake of U(VI) from aqueous media by magnetic Schiff's base chitosan composite

Abstract Schiff's base chitosan composite with magnetic properties has been prepared and investigated. The modification process took place through the reaction between chitosan and polymeric Schiff's base of thiourea/glutaraldehyde in the presence of magnetite. The sorption characteristics of the composite towards UO 2 2 + at different experimental conditions were carried out by means of batch and column methods. The composite showed high affinity and fast kinetics for the sorption of UO 2 2 + ions, the sorption capacity reached 2.32 mmol/g at 25 °C. Various parameters such as pH, agitation time, UO 2 2 + concentration and temperature had been studied. The kinetics and thermodynamic behavior of the sorption reaction were defined. These data indicated an exothermic and spontaneous sorption process, and kinetically followed pseudo-second order model, Fickian diffusion low and Elovich equation. The uptake of UO 2 2 + was slightly influenced by the increase of ionic strength. Breakthrough curves for the removal of UO 2 2 + were studied at different flow rates and bed heights. The critical bed height for the studied column was found to be 0.656 cm at flow rate of 4 mL/min. Hydrochloric acid (0.2 M) was used for desorbing UO 2 2 + from loaded composite: desorption yield as high as 97% was obtained.

The photo-electrical properties of the p-Si/Fe(II)–polymeric complex/Au diode

In this study, the Schiff base monomer was prepared by a common condensation method of salicylaldehyde and (E)-3-amino-4-((3-bromophenyl)diazenyl)-1H-pyrazol-5-ol. The poly(Schiff base) was synthesized from the oxidative polycondensation of the Schiff base monomer with NaOCl in an aqueous alkaline medium. After obtaining Schiff base polymer, Fe(II)–polymeric complex with Fe(II) of Schiff base polymer was successfully synthesized. Ligand, monomer, Schiff base polymer and Fe(II)–polymeric complex were characterized using elemental analysis, 1H NMR, 13C NMR, FT IR, GPC, UV–vis and magnetic susceptibility. Then, we fabricated the p-Si/Fe(II)–polymeric complex/Au diode and investigated the electronic and photoconductivity properties of the p-Si/Fe(II)–polymeric complex/Au diode by current–voltage measurements under dark and various illumination conditions. We calculated the electrical and photo-electrical parameters of the p-Si/Fe(II)–polymeric complex/Au diode such as the rectification ratio (r), ideality factor (n), barrier height (Φb), Richardson constant (A*), series (Rs) and shunt resistance (Rsh) and photocurrent (Iph), responsivity (R) and photoconductivity sensitivity (S). The obtained n values confirm the presence of a combination of recombination and diffusion currents in the p-Si/Fe(II)–polymeric complex/Au diode. The r, n, Φb, Rs and Rsh values of the p-Si/Fe(II)–polymeric complex/Au diode decreased with increasing illumination intensity. The Iph, R and S values of the p-Si/Fe(II)–polymeric complex/Au diode increased with increasing illumination intensity. The synthesized Fe(II)–polymeric complex exhibits semiconductor property, it can be used in production of the metal-semiconductor (Schottky) diode and it is sensitive to light. The p-Si/Fe(II)–polymeric complex/Au diode exhibits a photoconductivity effect.

Metal-based Schiff base polymers: preparation, spectral, thermal and their in vitro biological investigation

New polymer metal(II) complexes have been synthesized using Schiff base ligand, synthesized by the condensation reaction of 2-hydroxyacetophenone and o-phenylenediamine. The ligand and polymer metal(II) complexes have been characterized by micro-analytical, UV–vis, FT-IR, 1H-NMR spectral studies, as well as magnetic susceptibility and thermal studies. On the basis of spectral studies, a square-planar geometry has been proposed for the copper(II) polymer metal complex; manganese(II) polymer metal complex shows octahedral geometry while other polymer metal complexes have shown tetrahedral geometries. The in vitro antimicrobial activity of the compounds is tested against the bacteria Escherichia coli, Pseudomonas aeruginosa, Bacillius subtilis, Staphylococcus aureus, Salmonella typhi, and the fungi Candida albicans, Microsporum canis, and Aspergillus niger by well diffusion method. The polymer metal complexes show stronger antimicrobial activity than the free ligand and thermal studies were promising after coordination. The polymers represent a novel class of metal-based antimicrobial agents providing large number of opportunities for thermal and antimicrobial applications.

π-Conjugated Ferrocenyl Schiff Base Polymers: Synthesis, Characterization and Electrical Conductivity

Eight new dihydroxy monomers (SB-8SB) having inbuilt imine/azo moieties and alkoxy side groups were synthesized and polymerized successfully with diacid-chlorides namely isophthaloyl chloride (I), terephthaloyl chloride (T) and preformed 1, 1-dicarbonyl ferrocenyl chloride (Fe), by solution phase polycondensation. The structural characterization of resulting material was carried out using spectral techniques, 1H, 13C NMR and FTIR spectroscopic studies. In term of property exploration, influence of the chain architecture on the solubility behavior and thermal stability was studied. Molecular weight was determined by viscometer. Polymers were doped with iodine to study electrical conductivity of neat and doped macrochains at different temperatures. Attempt was made to explain significant increase registered in the case of doped material. .

Surface and Adsorption Parameters of Water Soluble Polymeric Surfactants Based on Ethoxylated Schiff Base Polymers in Aqueous Medium

This work aims to measure the adsorption and micellization parameters of new water soluble nonionic amphiphilic block and graft copolymers based on hydrophilic poly (ethylene glycol) (PEG) and hydrophobic poly (propylene oxide) (PPO) at ambient temperature and normal atmospheric pressure. The chemical composition and molecular weights of the prepared copolymers were determined from 1H NMR analyses. The surface properties of the prepared surfactants were determined by measuring the surface tension at different temperatures. The surface tension, critical micelle concentration and surface activities were determined at different temperatures. Surface parameters such as surface excess concentration, the area per molecule at interface and the effectiveness of surface tension reduction were determined from the adsorption isotherms of the prepared surfactants. Some thermodynamic data for the adsorption and micellization process were calculated and are discussed.

Electric Desalting and Dewatering of Crude Oil Emulsion Based on Schiff Base Polymers As Demulsifier

Electric Desalting and Dewatering of Crude Oil Emulsion Based on Schiff Base Polymers As Demulsifier

A novel non-competitive amperometric immunosensor by using thiourea-glutaraldehyde-modified gold electrode for immunoglobulin M detection

A novel non-competitive amperometric immunosensor based on a self-assembled monolayer (SAM) of thiourea modified by a polymeric Schiff's base of glutaraldehyde on gold electrode has been developed for determination of IgM. Alkaline phosphatase (ALP)-conjugated monoclonal anti-mouse immunoglobulin M (IgM) antibody was selectively bound to IgM molecules onto the surface of the electrode. Electrochemical response arising from the catalytic reaction of alkaline phosphatase enzyme. Its reaction with various phosphates such as p-aminophenyl phosphate and p-nitrophenyl phosphatase (p-NPP) generates the electrochemically active products p-aminophenol (p-AP) and p-nitrophenol (p-NP), respectively.

Viscometric Study of Bis(cinnamaldehyde) and Their Schiff Base Polymers in DMF and THF Solution at 30 ºC

Viscometric Study of Bis(cinnamaldehyde) and Their Schiff Base Polymers in DMF and THF Solution at 30 ºC

Synthesis, Characterization, Viscosity and Thermo Analytical Studies of Schiff Base Polymers Derived from 6,6-Methylene bis(1-napthaldehyde)

Synthesis, Characterization, Viscosity and Thermo Analytical Studies of Schiff Base Polymers Derived from 6,6-Methylene bis(1-napthaldehyde)

Vanillin-Based Polymers—part II: Synthesis of Schiff Base Polymers of Divanillin and Their Chelation with Metal Ions

Condensation of renewable resources-based monomer divanillin with alkyl diamines gives Schiff base polymers with degree of polymerization (DP) ~25–32 in 88–95% yield. These yellow polymers are insoluble in water and common organic solvents, slightly soluble in warm DMSO, DMF and dissolves in aqueous NaOH. The polymers were characterized using FT-IR, 1H, and 13C NMR spectroscopy and by comparison with the model compound N,N′-bis(vanillidene)-1,3-propanediamine. Polymer prepared by condensation of divanillin and 1,6-diaminohexane is shown to chelate with Cu(II), Fe(II), and Co(II) metal ions in basic aqueous methanol.

Low band gap Schiff base polymers obtained by complexation with Lewis acids

Two Schiff base polymers were prepared from the respective monomers by condensation method using toluene and N-methyl-2-pyrrolidinone as solvent. They were complexed with Al(III), In(III), and Cu(II) trifluoromethane sulfonates (triflates), and AlCl3 Lewis acids and characterized by FT-IR, UV–Vis spectroscopy, and scanning electron microscopy (SEM). Homogeneous films were prepared by spin coating in the presence and absence of Lewis acids. Polymer–Lewis acid interaction was confirmed by FT-IR, UV–Vis spectroscopy, and SEM. Lewis acid composition in polymers was determined by FT-IR spectroscopy. Absorption spectra of these conjugated Schiff base polymer complexes exhibited smaller optical band gap than pristine polymers. These variations ranged from 2.4 to 1.4 and 3.3 to 2.0 eV. Absorption depends on the Lewis acid in the polymer and band gap on the nature of the metal incorporated in the polymeric backbone. Solubility increased by complexation. The obtained complexes were soluble in trifluoroacetic and formic acids and in m-cresol. Polymer–Lewis acid solutions in m-cresol were stable for 98 h; the others remained stable over several months. The results of this study revealed that optical, solubility, and band-gap properties of conjugated Schiff base polymers can be modified by Lewis acids and these could be studied by optoelectronics.

Novel conducting polySchiff base of N-(3-aminopropyl) pyrrole-salicylaldehyde and its copolymers with pyrrole: synthesis and characterization

Novel Schiff base polymer of N-(3-aminopropyl) pyrrole-salicylaldehyde and its copolymers with pyrrole were synthesized by interfacial polymerization, ultrasonic method, and electrochemical polymerization with the aim of producing and characterizing a new class of polymeric materials which could be used as separator of heavy metals such as Cu2+ and Ni2+. For this purpose, Schiff base structure was synthesized by condensation reaction of N-(3-aminopropyl) pyrrole with salicylaldehyde and that N-(3-aminopropyl) pyrrole was prepared from reduced product of pyrrole with 3-chloropropionitrile by lithium aluminum hydride (LiAlH4). The copolymers were synthesized with various molar ratios of pyrrole to N-(3-aminopropyl) pyrrole-salicylaldehyde (30:70, 40:60, and 50:50), via interfacial polymerization and also molar ratio of pyrrole to N-(3-aminopropyl) pyrrole-salicylaldehyde 30:70, via ultrasonic technique. The chemical structures of synthesized polymers and precursors were investigated by FT-IR and 1H NMR. Thermal behavior of polymers was investigated by thermal gravimetric analysis. Morphology of synthesized polymers was studied by scanning electron microscopy (SEM), the conductivity of obtained polymers was investigated by four-probe conductivity measurement technique and the electroactivity behavior of synthesized polymers was investigated by cyclic voltammetry (CV) method. In proof, the ability of polymers in absorption of Ni(II) and Cu(II) was obtained from atomic absorption analysis. Secondly, the homopolymer of N-(3-aminopropyl) pyrrole and its copolymers with pyrrole were prepared by electrochemical polymerization CV in various molar ratios and the electroactivity behavior of synthesized polymers was investigated.

An investigation on new high performance Schiff base polyurethanes

Novel poly(urethane-azomethine-thiourea)s (PUATs) were synthesized via one-step polymerization from newly prepared diol chain extender (1,4-phenylene bis((E)-1-(4-hydroxobenzylidene)thiourea) (PBHBT)), containing C=S and –C=N– linkages, along with 1,4-phenylene diisocyanate (PDI) as hard segments and 20, 40 and 60 mol.% polyethylene glycol (PEG) forming soft segments. The prepared chain extender and polymers were characterized via elemental, Fourier transform infrared, 1H- and 13C-NMR analyses, and physical properties such as ηinh, solubility, crystallinity, flame retardancy and thermal stability were studied. According to X-ray diffraction patterns, the Schiff base polymers exhibited amorphous morphologies and their molar masses were in the range of 148 × 103–163 × 103 g mol−1. Thermogravimetric analysis indicated that PUATs with 20 and 40 mol.% PEG were fairly stable above 500°C having T10 of 511–527°C and had high glass transition temperatures about 249–251°C. In comparison with typical polyurethanes, PUATs with lower polyol content exhibited better non-inflammability, Tg values, chemical and thermal stability owing to rigid hard segment structure.

Antimicrobial Polychelates: Synthesis and Characterization of Transition Metal Chelated Barbituric Acid–Formaldehyde Resin

A monomeric Schiff base was prepared by the condensation reaction of salicylaldehyde and semicarbazide, which further react with formaldehyde and barbituric acid-formed polymeric Schiff base. Its metal polychelates were then formed with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II). All the synthesized compounds were characterized by elemental analysis, magnetic moment, FTIR, 1HNMR, and electronic spectroscopies. The elemental analysis data show the formation of 1:1 [M: L] metal polychelates. Thermogravimetric analysis was carried out to find the thermal behavior of all the synthesized polymeric compounds and thermal data revealed that all the metal polychelates are more thermally stable than their parent polymeric Schiff base. All the synthesized polymeric compounds were screened for antimicrobial activity against some clinically important microorganisms, such as Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus, Staphylococcus typhi, Candida albicans, Microsporum canis, and Aspergillus niger. In vitro antimicrobial activity was determined by the Agar Well Diffusion method and the result shows that all the metal polychelates exhibited better antimicrobial activity than their parent polymeric Schiff base.

Schiff Base Polymers Obtained by Oxidative Polycondensation and Their Co(II), Mn(II) and Ru(III) Complexes: Synthesis, Characterization and Catalytic Activity in Epoxidation of Styrene

In this paper, Schiff base monomers having double azomethine groups, N,N′-bis(4-hydroxybenzylidene)1,4-phenylenediamine (M1) and N,N′-bis(4-hydroxysalicylidene)1,4-phenylenediamine (M2), were prepared by a common condensation reaction between 4-hydroxybenzaldehyde and 4-hydroxysalicylaldehyde with 1,4-phenylenediamine, respectively. The new Schiff base polymers, poly(N,N′-bis(4-hydroxybenzylidene)1,4-phenylenediamine) (P1) and poly(N,N′-bis(4-hydroxysalicylidene)1,4-phenylenediamine) (P2) were synthesized from the oxidative polycondensation of monomers with NaOCl in an aqueous alkaline medium. The characterization of synthesized monomers and polymers was carried out by FT-IR, UV-Vis, 1H-NM, 13C-NMR and elemental analysis. The new polymer–metal complexes were prepared by using polymers and Co(II), Mn(II) and Ru(III) metal salts. Thermal properties of the compounds were studied by TG-DTA techniques. In addition, the catalytic properties of the polymers and their metal complexes were investigated in epoxidation reactions of styrene. The results of the catalysis studies were monitored by GC–MS.

Synthesis and crystal structure of polymeric thiocyanato-bridged copper(II) complex with 4-nitro-2-[(2-piperidin-1ylethylimino)methyl] phenolate

A polymeric thiocyanato-bridged Schiff base copper(II) complex [Cu(L)(NCS)]n, where L is 4-nitro-2-[(2-piperidin-1-ylethylimino)methyl]phenolate, has been synthesized and structurally characterized by elemental analysis, infrared spectra, and single crystal X-ray diffraction. The complex crystallizes in the monoclinic space group P21 with a = 8.527(5), b = 10.296(6), c = 9.697(6) A, β = 103.77(2)°, V = 826.8(8) A3, Z = 2. In the complex, the Cu atom is in a square pyramidal coordination with one O and two N donor atoms of the Schiff base ligand and with one thiocyanate N atom, defining the basal plane, and with one symmetry related thiocyanate S atom occupying the apical position. The thiocyanate ligand links the Cu atoms through the end-to-end bridging mode.

Two lantern-like 1D polymeric Schiff base copper(i/ii) complexes derived from copper(ii) salts containing rarely seen [CuI(NCS)4] bridges

Two lantern-like 1D polymeric Schiff base copper(I/II) complexes containing rarely seen [CuI(NCS)4] bridges have been obtained by reaction of tridentate Schiff bases, copper(II) salts, and ammonium thiocyanate in methanol under mild condition.

A 1D Schiff base zinc polymer as a versatile metallo-ligand for the synthesis of polynuclear zinc cages

The 1D polymeric Schiff base zinc complex, [LZn(2)Et(2)](n), where LH(2) = (NN'-ethylene-bis(4-iminopentan-2-one)) has been demonstrated as a useful synthetic metallo building block for the synthesis of homo and heteronuclear zinc cages. The reaction of [LZn(2)Et(2)](n) with CdI(2) afforded the hetero-nuclear cage, 1, [L(2)Zn(4)(Et)(2)CdI(4)], while reaction with HgI(2) afforded a hexanuclear zinc cage, [L(2)Zn(6)(Et)(4)(μ(4)O)(μ(3)OEt)I], 2. The versatility of [LZn(2)Et(2)](n) as a metallo building block is demonstrated through the reaction with ferrocenyl carboxylic acid, affording the ferrocenyl supported zinc cage, [L(2)Zn(8)(FcCO(2))(4)(Et)(2)(OEt)(2)(μ(4)O)(2)], 3, while the reaction with Er(III) acetate afforded the decanuclear zinc cage, [L(3)Zn(10)(μ(4)O)(4)(Et)(6)], 4.