Cationic starch iodophores

Cross‐linked cationic starches N‐(2‐hydroxyl)propyl‐3‐trimethyl ammonium starch chloride (CQS chloride), N‐(2‐hydroxyl)propyl‐3‐trimethyl ammonium starch iodide (CQS iodide), and N‐(2‐hydroxyl)propyl‐3‐trimethyl ammonium starch iodide–iodine (CQS triiodide) with the degree of substitution (DS) according to cationic groups from 0.04 to 0.62, as well as cross‐linked starch–iodine complexes were synthesized and tested as potential antibacterial agents. Cationic starch iodine derivatives were obtained during ion exchange reaction between CQS chloride and iodide or iodide–iodine anions in aqueous solutions. CQS_DS≤0.3 chloride can form several types of iodine complexes, such as the blue amylose–iodine inclusion complex and ionic CQS⁺I^?·(I₂)_m complex (m ≥ 1). The antibacterial activity of modified starches–iodine samples against different pathogenic bacterial cultures and contaminated water microorganisms was evaluated. CQS chloride and CQS iodide were found to be bacteriostatic. A strong antibacterial activity was characteristic of CQS triiodides in which molecular iodine is present in both ionic and inclusion complexes. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Interaction of polydiallyldimethylammonium salts with iodine

The interaction between polydiallyldimethylammonium chloride (PDADMAC) and KI or KBr, followed by changes in conformation of macromolecules, coil compaction, and counterion exchange, was detected by means of turbidimetry and viscometry. In aqueous solutions at presence of KI, PDADMAC rapidly binds iodine by the formation of polymer–iodine complexes PDADMA I^? I_m (m ≤ 4). Spectrophotometric investigations of the interaction in water without KI prove the formation of complexes of polyquaternary ammonium chloride or bromide with iodine only via iodide. These ions can be generated in the polymer‐catalyzed hydrolysis reaction of iodine. By inducing hydrolysis of iodine and binding the eventually formed iodide, PDADMAC acts as an iodine acceptor with self‐strengthening capacity. For the sorption of gaseous iodine, the possibility of direct interaction of its dipoles with the charged groups of the polyelectrolyte is also reasoned. Polydiallyldimethylammonium halides were used to modify activated carbon and employed in a nuclear power station for treatment of outlet gases containing radioactive iodine. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2710–2716, 2006     

The volatilization of iodine species over dilute iodide solutions

The volatility of iodine above dilute CsI solutions has been investigated experimentally. The partitioning of iodine between air and solutions prepared with iodide was found to increase with decreasing _pH and iodide concentration. Aqueous to gaseous partition coefficients ranging from 3 X 10³ to 10⁷ were observed indicating that only a very small fraction of the iodide was oxidized to volatile forms. It was concluded that under these very dilute conditions, the rate of iodide oxidation was proportional to the square root of the iodide concentration; the rate also depended on _pH under acidic conditions but not under basic conditions.     

Iodine number determination of milk fat and vegetable fats by refractometry

A refractometric method for the estimation of iodine number of milk fat has been suggested. About 0.2 ml of milk fat was iodinated with ca. 10 ml Wijs iodine reagent for 3 min using mercuric acetate as catalyst. The iodinated fat showed a higher refractive index than the original fat. The changes in refractive indices showed a very high correlation with the iodine values of the fats (T=0.9993). The average of the ratios of change in refractive index to iodine number was 50.7×10⁻⁵, from which the iodine number of milk fat can be calculated. The method can also be applied to vegetable fats. The ratios of change in refractive index to iodine number for the oils of peanut, rapeseed, soybean, niger, sesame, and sunflower were similar, and the average was 45.2×10⁻⁵. The ratio for linseed oil was 38.4×10⁻⁵, and for coconut fat it was similar to that of milk fat.     

Synthesis and Electrical Properties of Three Novel Poly(Ferrocenyl-Schiff Bases) and Their Charge Transfer Complexes with Iodine

Three ferrocenyl-Schiff base monomers were synthesized by the condensation of ferrocenecarboxaldehyde and phenylenediamine under neutral conditions, and then used to produce copolymer materials with terephthaloyl chloride monomer by the Friedel–Crafts method. The model compound and copolymers of three novel poly(ferrocenyl-Schiff bases) and their charge transfer complexes with iodine were successful obtained and their structures were characterized by ¹H-NMR, infrared, and ultraviolet spectra. The effect of degree of iodine doping on their structures was studied. It appears that poly-p-bis(ferrocenyl-Schiff base) can be doped to a higher iodine level than the other two prepared materials. Electrical measurement results showed that the conductivity can be increased several orders of magnitude after doping with iodine. The maximum conductivity at room temperature is 3.17 × 10⁻⁴ S cm⁻¹ indicating that the conducting polymer has potential as a semiconductor material.     

Gamma-initiated iodination of methane in the gas phase

Gamma radiation has been used to initiate the gas phase reaction between iodine and methane. Under appropriate conditions, the products are hydrogen iodide and the iodomethanes. The experiments were conducted over a range of temperature, concentration, and at two levels of total absorbed dose. The existence of a chain reaction is presumed, on the basis of G-values, which were as high as 7 × 10⁷. In view of the propensity of iodine as a radical scavenger, this high efficiency might seem surprising, but may be attributable to the known autocatalyic effect of iodine in substitution reactions.     

Facile Fabrication of Povidone Iodine-Embedded Polytetrafluoroethylene Superhydrophobic Films with Improved Antiadhesive and Bactericidal Properties in Bacterial Environments

It remains a challenge to maintain the antiadhesion properties of superhydrophobic films after exposure to bacterial environments. In this work, superhydrophobic bactericidal polymer films via the simple incorporation of polyvinylpyrrolidone-iodine (PVP-I) or iodine into polytetrafluoroethylene (PTFE) are fabricated to improve their antiadhesive and antibacterial capability. Superhydrophobic iodine-embedded films, polytetrafluoroethylene/polyvinylpyrrolidone-iodine and polytetrafluoroethylene-iodine (PTFE/PVP-I and PTFE-I), show excellent antiadhesive and bactericidal performances even post exposure to bacterial solutions as compared to iodine-free counterparts by controlling the release of iodine. Especially, superhydrophobic PTFE/PVP-I films display a more sustained iodine release profile and significant antibacterial properties against gram-positive (S. aureus, methicillin-resistant S. aureus (MRSA)) and gram-negative (E. coli) bacteria. Such a facile combination of antiseptic agents and superhydrophobic surface could be widely used for antiseptic biomedical applications.     

The reaction of polyaniline with iodine

Polyaniline (PANI) (emeraldine) base has been exposed to iodine in an ethanol-water suspension. The conductivity of PANI increased from 10⁻⁹ S cm⁻¹ to 10⁻⁴ S cm⁻¹ already at the molar ratio [I₂]/[PANI] = 1, and a higher content of iodine had only a marginal effect. This is the result of the protonation of PANI base with hydriodic acid, which is a by-product of the oxidation of the emeraldine form of PANI to pernigraniline constitutional units. The reaction is discussed on the basis of FTIR spectra. An alternative reaction, a ring-iodination of PANI, is marginal. Only one iodine atom substitutes a hydrogen atom in about 12 aniline units, even at high iodine concentration, [I₂]/[PANI] = 8. The film of polyaniline base can be used in sensing iodine; after exposure to the iodine vapor, the conductivity of the polyaniline film increased.     

The synthesis and characterization of 2-(2′-pyridyl)benzimidazole heteroleptic ruthenium complex: Efficient sensitizer for molecular photovoltaics

The novel ligand 1-(2,4,6-trimethylbenzyl)-2-(2′-pyridyl)benzimidazole and its heteroleptic ruthenium (II) complex were synthesized. The complex was characterized using spectroscopic methods and cyclic voltammetry. Charge-separation was investigated within nanoporous titanium dioxide employing surface photovoltage spectroscopy. The performance of the ruthenium complex as a charge transfer photosensitizer in nanocrystalline, titanium dioxide-based, dye sensitized solar cells was studied under standard AM 1.5 sunlight using an electrolyte consisting of 0.6 M 1-butyl-3-methyl-imidazolium iodide, 0.1 M lithium iodide, 0.05 M iodine and 0.5 M 4-tert-butyl pyridine in 3-methoxy propyonitrile. The novel complex had a photocurrent density of 9.47 mA cm⁻², 600 mV open circuit potential and 0.60 fill factor yielding an efficiency of 3.4%. The photovoltaic performance of the colorant was compared with that of cis-bis(isothiocyanato)(2,2'-bipyridyl-4,4'-dicarboxylato) (2,2’-bipyridyl-4,4’-di-nonyl) ruthenium(II); both compounds exhibited similar efficiency, while the fill factor value was higher for the novel dye.     

Amelioration of electrochemical and photovoltaic performances on P(VP‐co‐VAc) based gel polymer electrolyte by incorporating double salt for dye‐sensitized solar cells

Dye‐sensitized solar cell (DSSC) is an alternative photovoltaic application used to replace the liquid electrolyte dependent conventional photovoltaic cell. In this research, gel polymer electrolyte (GPE) was used to replace the unstable liquid electrolyte. This GPE consists of poly[1‐vinylpyrrolidone‐co‐vinyl acetate] (P[VP‐co‐VAc]), tetrabutylammonium iodide (TBAI), sodium iodide (NaI), iodine (I₂), ethylene carbonate (EC), and propylene carbonate (PC). The GPE was tested for its ionic conductivity and an optimum level was reached at sample with 30% TBAI and 6% NaI at 1.17 × 10^?3 S cm^?1. The DSSC was then fabricated with all GPEs and a photovoltaic performance study was conducted. As a result, the highest photovoltaic conversion efficiency (PCE), η for a single salt was 3.04% for 40% TBAI. When a second salt is added, the system showed improvement in efficiency, η to 4.54% with short circuit current density, J_sc of 11.02 mA cm^?2 and open circuit voltage, V_oc of 0.67 V and FF of 61%. The other changes after the addition of TBAI and NaI salts have been observed through X‐ray diffraction, Fourier transformation and thermal analysis studies. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43805.     

Effects of substituents of imidazolium cations on the performance of dye-sensitized TiO2 solar cells

Imidazolium iodides (Im⁺I⁻s) were synthesized with different substituents of the cation and used as electrolytes in dye-sensitized solar cells (DSSCs), and the effects of such substituents were investigated in terms of the photovoltaic performance of the cells. Synthesized iodides were verified by ¹H-NMR. Among the iodides, 1,3-diethylimidazolium iodide enabled a solar energy conversion efficiency of 4.8% for its DSSC, while 1-(4-acetophenyl)-3-ethylimidazolium iodide rendered an efficiency of 3.1% for its cell. In all cases the short-circuit photocurrent (J _sc) was found to increase with decrease in size of the substituent, which was also verified to be valid in the case of a quasi-solid state DSSC. Results are explained by the electrostatic interactions between solvated Im⁺ and negatively charged species based on the correlation between diffusion coefficients of I⁻ and I₃⁻ and J _sc values. These explanations are supported by steady-state voltammetry and electrochemical impedance spectroscopy (EIS).     

Studies on the influence of iodide ions on the synergistic inhibition of the corrosion of mild steel in an acidic solution

The synergistic action caused by iodide ions on the corrosion inhibition of mild steel in 0.5 M H₂S0₄ in the presence of dicyclohexylamine (DCHA) has been investigated using potentiodynamic polarization, linear polarization and a.c. impedance techniques. DCHA inhibits the corrosion of mild steel in 0.5 m H₂SO₄ even at lower concentrations. The inhibition efficiency decreases with increase in the concentration of the amine. The addition of iodide ions enhances the inhibition efficiency to a considerable extent. The adsorption of this compound is also found to obey Langmuir's adsorption isotherm, thereby indicating that the main process of inhibition is by adsorption. The increase in surface coverage values in the presence of iodide ions indicates that DCHA forms an insoluble complex at lower amine concentrations by undergoing a joint adsorption. The synergism parameter (S) is defined and calculated both from inhibition efficiency and surface coverage values. This parameter in the case of DCHA is found to be more than unity, indicating that the enhanced inhibition efficiency caused by the addition of iodide ions is only due to synergism and there is a definite contribution from the inhibitor molecule. Thus, DCHA is then adsorbed by coulombic attraction on the metal surface where the I^– is already chemisorbed and thus reduces the corrosion rate.     

Investigation on the electro-oxidation of iodide in the room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate at platinum electrode

The oxidation behavior of iodide has been investigated by linear sweep voltammetry and cyclic voltammetry at a platinum electrode in the room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([C₄mim][BF₄]). The experimental results showed that iodide yielded two oxidation peaks P_a1 and P_a2 in [C₄mim][BF₄], and both of P_a1 and P_a2 are diffusion-controlled. P_a1 yielded from iodide to triiodide at +0.58 V is a two-electron oxidation wave, and P_a2 yielded from triiodide to iodine at +1.00 V is one-electron oxidation wave. Linear relationships between I_pa1 and the concentration of iodide can be established from 0.45 to 7.2 mmol L⁻¹ with a detect limit of 0.3 mmol L⁻¹ by linear sweep voltammetry, and from 0.30 to 7.8 mmol L⁻¹ with a detect limit of 0.2 mmol L⁻¹ by differential pulse voltammetry. These methods can be used for simple, rapid determination of iodide in the crude [C₄mim][BF₄].     

Optimizing Separation of Iodine from Halogen Interferences in Preparation for TIMS Analysis

Low-level analysis of radioiodine performed by TIMS requires an initial chemical separation from interfering higher electron-affinity halogens. Experiments using ¹²⁵I and ³⁶Cl tracers have shown that iodide can be selectively oxidized and purged from solution while the chloride remains in the solution. A systematic investigation of the experimental factors that affect the oxidation and transfer of iodine along with the separation of iodide from chloride has been completed. Experimental design was used to determine the optimum experimental conditions by obtaining a better understanding of factor affects and interactions. Factors such as gas purge rate, experiment run time, and oxidant concentration were simultaneously studied in a central composite design of experiments and response surfaces were generated from results. Optimizing experimental factors resulted in improved iodide oxidation and transfer efficiencies, halogen separation, and shorter analysis times.     

Reverse iodine transfer polymerization of vinyl acetate and vinyl benzoate: synthesis and characterization of homo‐ and copolymers

Homo‐ and copolymers of vinyl esters including vinyl acetate (VAc) and vinyl benzoate (VBz) were synthesized via the reverse iodine transfer radical polymerization technique. Polymerization was carried out in the presence of iodine as the in situ generator of the transfer agent and 2,2′‐azobis(isobutyronitrile) as the initiator at 70 °C. Reverse iodine transfer radical homopolymerization of VAc and VBz led to conversions of 76 and 57%, number‐average molecular weights of 8266 and 9814 g mol^?1 and molecular weight distributions of 1.58 and 1.49, respectively. The microstructure of the synthesized polymers was investigated in detail using gel permeation chromatography, ¹H NMR, ¹³C NMR and distortionless enhancement of polarization transfer (135° decoupler pulse) techniques. Relatively narrow molecular weight distribution and controlled and predictable trend of molecular weight versus conversion were observed for the synthesized polymers, showing that reverse iodine transfer radical homo‐ and copolymerization of VAc and VBz proceeded with controlled characteristics. Results of molecular weight and its distribution along with the ¹H NMR spectra recorded for homo‐ and copolymers indicated that side reactions can occur during the course of polymerization with a significant contribution when VAc, even in a small amount, was present in the reaction mixture. This can result in polymer chains with aldehyde dead end and broadening of the molecular weight distribution. © 2015 Society of Chemical Industry     

A study of iodine adlayers on polycrystalline gold electrodes by in situ electrochemical Rutherford backscattering (ECRBS)

Iodine adsorption on a polycrystalline gold electrode was studied by in situ electrochemical Rutherford backscattering (ECRBS) using an ultrahigh vacuum (UHV)-electrochemical cell comprising of a thin-film silicon nitride window. The depth resolution of RBS allowed for measurement of nuclide concentration of the diffuse double-layer, electrode surface and near-surface regions. ECRBS measurements on the gold electrode, initially exposed to −500 mV vs. a platinum pseudo-reference electrode, in a potassium iodide solution, showed an increase in the 2.07 MeV iodine peak indicative of iodine adsorption. The surface concentration of the iodine adlayer was directly measured by ECRBS to be 1.3 ± 0.3 nmol/cm². ECRBS measurements on a gold electrode exposed to 1.5 V vs. a platinum pseudo-reference electrode, in a potassium iodide solution display a decrease in the 2.16 MeV gold peak and a shift to lower energies. Scanning electron microscopy images of electrodes studied by ECRBS displayed roughened surfaces consistent with gold dissolution. This work demonstrates the potential for in situ ECRBS using thin-film silicon nitride windows to become a powerful tool for the investigation of a wide range of electrochemical processes in areas such as corrosion, electrodeposition and electrocatalysis.     

Chloramine T with iodine: A new reagent to determine the iodine value of edible oils

Chloramine T (N-chloro-p-toluenesulfonamide sodium salt) and iodine (2:1, w/w) in carbon tetrachloride and acetic acid (1:1, vol/vol), referred to as reagent (I) was found to be effective for the determination of Iodine value of edible oils. Reagent (I) reacted quantitatively with the double bonds of oils of known weight. The reagent left unreacted after 20–25 min was titrated against standard sodium thiosulfate solution (0.04 M) in presence of potassium iodide (10%, 5 mL). The difference in volume of sodium thiosulfate solution consumed by reagent (I) without and with oil was a basis to calculate the iodine value of oils used. The iodine values of different oils were also determined separately following the standard procedure of Wijs, and calculated iodine value was obtained from the gas chromatographic profile of fatty acids. The iodine value obtained by the new method was in agreement with the results of the standard methods. The results obtained indicate that the method could be a complementary or an alternative to the Wijs method.     

Interaction between iodine and ethyl cellulose

Interaction between iodine and ethyl cellulose was investigated by immersing ethyl cellulose membranes in aqueous iodine–iodide solution (iodine doping) and incorporating iodine in the solution from which the membrane was cast. Oxygen and nitrogen permeabilities in iodine‐doped ethyl cellulose decrease with an increase in the concentration of iodine in the dopant solution up to 0.003 mol L⁻¹ and increase sharply at higher iodine concentrations, and ultraviolet–visible and far‐infrared spectra indicate formation of a charge transfer complex. Differential scanning calorimetry of both types of membrane shows changes in the characteristic phase transitions of ethyl cellulose after iodine treatment, including the crystal–liquid crystal transition that has been reported to occur in ethyl cellulose. Further evidence for liquid crystal phases has been found from circular dichroism. X‐ray photoelectron spectroscopy of iodine‐doped ethyl cellulose films indicates that the iodine is present in two different chemical states, probably l and l₂. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1303–1314, 1999     

Synergistic effect of 2-mercapto benzimidazole and KI on copper corrosion inhibition in aerated sulfuric acid solution

2-Mercapto benzimidazole (MBI) was used as a copper corrosion inhibitor in aerated 0.5 mol L^–1 H₂SO₄ solutions. The inhibition efficiency (IE) increased with increasing MBI concentration to 74.2% at the 1 mM level. A synergistic effect existed when MBI and iodide ions were used together to prevent copper corrosion in sulfuric acid. It was found that IE reached 95.3% in 0.5 mol L^–1 H₂SO₄ solutions containing 0.75 mmol L^–1 MBI and 0.25 mmol L^–1 KI. X-ray photoelectron spectroscopy (XPS) analysis of the copper samples showed that a (Cu⁺MBI) complex film formed on the surface to inhibit the copper corrosion and the iodide ions did not participate in the formation of the inhibitor film. The synergistic effect was attributed to the adsorption of iodide anions on the copper surface, which then facilitated the adsorption of protonated MBI and the formation of an inhibitive film.     

Effect of citrate and tartrate on phosphate adsorption by amorphous ferric hydroxide

Curves for P adsorption by ferric hydroxide in the presence of citrate and tartrate were prepared. From the curves, it appeared as though tartrate at 10^–4 M has no effect on P adsorption up to 750µmol P g^–1 ferric hydroxide adsorbed. However, observation of flocculation patterns show that even when the curves are identical, there is a difference in the way P is adsorbed in the presence of tartrate and citrate in terms of the type of site that is attacked.Assessment of phosphate - citrate competition using³²P and¹⁴C showed that citrate is less readily adsorbed by ferric hydroxide than tartrate and that citrate dissolves adsorption sites more readily than tartrate.The implications of this study are that root exudates containing a greater amount of tartrate would cause more efficient use of added P by plants since tartrate occupies the high affinity sites and therefore reduces phosphate fixation. Plants which produce root exudates high in citrate content would be able to utilize more fixed P than plants which produce exudates lower in citrate content because citrate dissolves sites at which P is held.