How molecular internal‐geometric parameters affect PB‐PEO polymersome size in aqueous solution

Amphiphilic polybutadiene polyethylene oxide (PB‐PEO) is one of the best known chemistries to form stable vesicular morphologies, stated as polymersomes, in aqueous environment. Mimicking cell membranes, these structures self‐assemble in an “amphiphilic window” determined by 0.15 < f < 0.35 where f is the ratio between the hydrophilic block volume and the entire diblock volume. However the polymersome size distribution also depends on molecular weight (M_n) and in order to gain insight on how f and M_n together determine polymersome size, we prepared PB‐PEO diblock copolymers with different block lengths and analyzed vesicle morphology via Dynamic light scattering (DLS) and Freeze‐fracture transmission electron microscopy (FF‐TEM). We found three main regimes: high f / low M_n with polymersomes of mixed diameter, high f / high M_n with mainly large polymersomes and low f, with mainly small polymersomes. In the first region, the polymersomes are highly polydisperse. There is a tendency towards increased diameter with increasing f and M_n. Taken together our findings can help to identify how polymersome self‐assembly can be controlled to achieve size distribution specificity alleviating the need for subsequent tuning of size via extrusion. This can pave the way for cost‐effective upscaling of polymersome production for biomedical and biomimetic applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 699–708     

Solution properties of stilbene‐containing sterically crowded alternating polyanions

Sterically crowded stilbene‐containing alternating polyanions were prepared via an indirect strategy of synthesizing “protected” monomers followed by deprotection and neutralization of the polyanion precursors. The solution properties of these new sterically crowded polyelectrolytes were studied. Steady‐state solution shear rheology showed a pronounced polyelectrolyte effect. The persistence lengths of these polyelectrolytes were determined. The dissociation behavior of the polyanions was investigated by pH titration with HCl, and multistep dissociation behavior was observed. Chain size and aggregation were studied by using DLS at varying ionic strengths. Polyelectrolytes behaved like rigid‐rods and formed concentrated solutions at the polymer concentration of 1.0 mg mL^?1. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1565–1570     

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     

Allyl ethers as combined plasticizing and crosslinkable side groups in polycarbonate‐based polymer electrolytes for solid‐state Li batteries

Allyl ether‐functional polycarbonates, synthesized by organocatalytic ring‐opening polymerization of the six‐membered cyclic carbonate monomer 2‐allyloxymethyl‐2‐ethyltrimethylene carbonate, were used to prepare non‐polyether polymer electrolytes. UV‐crosslinking of the allyl side groups provided mechanically stable electrolytes with improved molecular flexibility—T_g below ?20 °C—and higher ionic conductivity—up to 4.3 × 10^?7 S/cm at 25 °C and 5.2 × 10^?6 S/cm at 60 °C—due to the plasticizing properties of the allyl ether side groups. The electrolyte function was additionally demonstrated in thin‐film Li battery cells. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2128–2135     

Synthesis of linear and star‐like poly(ε‐caprolactone)‐b‐poly{γ‐2‐[2‐(2‐methoxy‐ethoxy)ethoxy]ethoxy‐ε‐caprolactone} amphiphilic block copolymers using zinc undecylenate

Linear and star‐like amphiphilic diblock copolymers were synthesized by the ring‐opening polymerization of ε‐caprolactone and γ‐2‐[2‐(2‐methoxyethoxy)ethoxy]ethoxy‐ε‐caprolactone monomers using zinc undecylenate as a catalyst. These polymers have potential applications as micellar drug delivery vehicles, therefore the properties of the linear and 4‐arm star‐like structures were examined in terms of their molecular weight, viscosity, thermodynamic stability, size, morphology, and drug loading capacity. Both the star‐like and linear block copolymers showed good thermodynamic stability and degradability. However, the star‐like polymers were shown to have increased stability at lower concentrations with a critical micelle concentration (CMC) of 5.62 × 10^?4 g L^?1, which is less than half the concentration of linear polymer needed to form micelles. The star‐like polymeric micelles showed smaller sizes when compared with their linear counterparts and a higher drug loading capacity of doxorubicin, making them better suited for drug delivery purposes. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3601–3608     

Polymersome‐forming amphiphilic glycosylated polymers: Synthesis and characterization

Copper‐catalyzed azide‐alkyne cycloaddition (CuAAC) was used to prepare glycosylated polyethylene (PE)–poly(ethylene glycol) (PEG) amphiphilic block copolymers. The synthetic approach involves preparation of alkyne‐terminated PE‐b‐PEG followed by CuAAC reaction with different azide functionalized sugars. The alkyne‐terminated PE‐b‐PEG was prepared by etherification reaction between hydroxyl‐terminated PE‐b‐PEG (M_n ～ 875 g mol^?1) and propargyl bromide and azidoethyl glycosides were prepared by glycosylation of 2‐azidoethanol. Atmospheric pressure solids analysis probe‐mass spectrometry was used as a novel solid state characterization tool to determine the outcome of the CuAAC click reaction and end‐capping of PE‐b‐PEG by the azidoethyl glycoside group. The aqueous solution self‐assembly behavior of these amphiphilic glycosylated polymers was explored by TEM and dye solubilization studies. Carbohydrate‐bearing spherical aggregates with the ability to solubilize a hydrophobic dye were observed. The potential of these amphiphilic glycosylated polymers to self‐assemble via electro‐formation into giant carbohydrate‐bearing polymersomes was also investigated using confocal fluorescence microscopy. An initial bioactivity study of the carbohydrate‐bearing aggregates is furthermore presented. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5184–5193     

EDOT‐diketopyrrolopyrrole copolymers for high bulk hole mobility and near infrared absorption

To obtain novel low‐bandgap materials with tailored hole‐transport properties and extended absorption, electron rich 3,4‐ethylenedioxythiophene is introduced as a comonomer in diketopyrrolo[3,4‐c]pyrrole copolymers with different aryl flanking units. The polymers are characterized by absorption and photoluminescence spectroscopy, dynamic scanning calorimetry, cyclic voltammetry, and X‐ray diffraction. The charge transport properties of these new materials are studied carefully using an organic field effect transistor geometry where the charge carriers are transported over a narrow channel at the semiconductor/dielectric interface. These results are compared to bulk charge carrier mobilities using space‐charge limited current (SCLC) measurements, in which the charge carrier is transported through the complete film thickness of several hundred nanometers. Finally, charge carrier mobilities are correlated with the electronic structure of the compounds. We find that in particular the thiophene‐flanked copolymer PDPP[T]₂‐EDOT is a very promising candidate for organic photovoltaics, showing an absorption response in the near infrared region with an optical bandgap of 1.15 eV and a very high bulk hole mobility of 2.9 × 10^?4 cm² V^?1 s^?1 as measured by SCLC. This value is two orders of magnitudes higher than SCLC mobilities reported for other polydiketopyrrolopyrroles and is in the range of the well‐known hole transporting polymer poly(3‐hexylthiophene). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 639–648     

Solution polymerization of polybenzimidazole

Polybenzimidazoles (PBI) are an important class of heterocyclic polymers that exhibit high thermal and oxidative stabilities. The two dominant polymerization methods used for the synthesis of PBI are the melt/solid polymerization route and solution polymerization using polyphosphoric acid as the solvent. Both methods have been widely used to produce high‐molecular weight PBI, but also highlight the obvious absence of a practical organic solution‐based method of polymerization. This current work explores the synthesis of high‐molecular weight meta‐PBI in N,N‐dimethyl acetamide (DMAc). Initially, model compound studies examined the reactivity of small molecules with various chemical functionalities that could be used to produce 2‐phenyl‐benzimidazole in high yield with minimal side reactions. ¹H NMR and FTIR studies indicated that benzimidazoles could be efficiently synthesized in DMAc by reaction of an o‐diamine and the bisulfite adduct of an aromatic aldehyde. Polymerizations were conducted at various polymer concentrations (2‐26 wt % polymer) using difunctional monomers to optimize reaction conditions in DMAc which resulted in the preparation of high‐molecular weight m‐PBI (inherent viscosities up to 1.3 dL g^?1). TGA and DSC confirmed that m‐PBI produced via this route has comparable properties to that of commercial m‐PBI. This method is advantageous in that it not only allows for high‐polymer concentrations of m‐PBI to be synthesized directly and efficiently, but can be applied to the synthesis of many PBI derivatives. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1795–1802     

Proton‐conducting polymers based on benzimidazoles and sulfonated benzimidazoles

A sulfonated derivative of polybenzimidazole is reported, and its properties are analyzed in comparison with related polybenzimidazole proton‐conducting materials. Poly(2,5‐benzimidazole), poly(m‐phenylenebenzobisimidazole), and poly[m‐(5‐sulfo)‐phenylenebenzobisimidazole] were prepared by condensation of the corresponding monomers in polyphosphoric acid. Several adducts of these polymers with phosphoric acid were prepared. The resulting materials were characterized by chemical analysis, Fourier transform infrared spectroscopy, and thermogravimetric analysis; also, the dc conductivity of doped and undoped derivatives was measured. Similar to what has been observed for the commercial polybenzimidazole polymer (also examined here for comparison), the title polymers exhibit high thermal stability. Furthermore, their doping with phosphoric acid leads to a significant increase in conductivity from less than 10^?11 Scm^?1 for the undoped polymers to 10^?4 Scm^?1 (both at room temperature) for their acid‐loaded derivatives. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3703–3710, 2002     

Synthesis of molecularly imprinted polypyrrole as an adsorbent for solid‐phase extraction of warfarin from human plasma and urine

The aim of this work was to develop a method for the clean‐up and preconcentration of warfarin from biological sample employing a new molecularly imprinted polymer (MIP) as a selective adsorbent for solid‐phase extraction (SPE). This MIP was synthesized using warfarin as a template, pyrrole as a functional monomer and vinyl triethoxysilane as a cross‐linker. The molar ratio of 1:4:20 (template–functional monomer–cross‐linker) showed the best results. Nonimprinted polymers (NIPs) were prepared and treated with the same method, but in the absence of warfarin. The prepared polymer was characterized by Fourier transmission infrared spectrometry and scanning electron microscopy. An adsorption process (SPE) for the removal of warfarin using the fabricated MIPs and NIPs was evaluated under various conditions. Effective parameters on warfarin extraction, for example, type and volume of elution solvent, pH of sample solution, breakthrough volume and maximum loading capacity, were studied. The limits of detection were in the range of 0.0035–0.0050 µg mL^?1. Linearity of the method was determined in the range of 0.0165–10.0000 µg mL^?1 for plasma and 0.0115–10.0000 µg mL^?1 for urine with coefficients of determination (R²) ranging from 0.9975 to 0.9985. The recoveries for plasma and urine samples were >95%. Copyright © 2015 John Wiley & Sons, Ltd.     

D–π–A polysulfones for blue electroluminescence

Donor–π–acceptor type fluorene‐based copolymers with a sulfone unit were designed and synthesized for application in efficient pure‐blue light emitting. The electroluminescence behaviors of these copolymers were investigated by fabricating light‐emitting diodes and electrochemical cell devices. The former device little functioned but the latter worked well. The electrochemical cell devices having a configuration of ITO/PEDOT:PSS/copolymer:ionic liquid/Al exhibited purplish blue electroluminescence with an emission maximum at 434 nm (CIE coordinates (x, y) = (0.17, 0.10)) measured at 7 V. The initial positive scan of the D–π–A polysulfone based light emitting electrochemical cell with a sweep rate of 0.1 V s^?1 afforded a maximum luminance of 1080 cd m^?2 with a current efficiency of 1.96 cd A^?1 at an operating voltage of 12.5 V. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3454–3461     

DOSY NMR as a tool for predicting optimal conditions for hydrogel formation: The case of a hyperbranched polyglycidol cross‐linked with boronic acids

This article demonstrates the utility of DOSY NMR for the determination of the optimal conditions for the efficient covalent, reversible cross‐linking of macromolecules in water for hydrogel formation. The studied model system was hyperbranched polyglycidol (HbPGL) containing numerous diol groups in peripheral regions and two types of boronic acids, that is, B(OH)₄^? and benzene‐1,4‐boronic diacid, as cross‐linking agents. Diffusion coefficient changes of a polymer in solution, under the influence of various concentrations of cross‐linking agent and pH, which influences the equilibrium of the reaction between boronic acids and diols, were recorded. These data are consistent with the rheological properties, namely the G′_max(ω) of hydrogels prepared under analogous conditions, from more concentrated solutions of HbPGL. This approach appears to be promising as it facilitates avoiding the loss of a large amount of polymer that is necessary for the elaboration of appropriate conditions for network formation in aqueous media. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2171–2178     

Waveguiding properties in dye‐doped submicron poly(N–vinylcarbazole) fibers

Dye‐doped submicron poly(N‐vinylcarbazole) fibers having mean diameters of 290–430 nm were fabricated via electrospinning and their waveguiding properties were investigated. The middle of each fiber's length was excited with UV light and guided photoluminescence (PL) was measured at the end of each of the fibers for different propagation lengths. The spectral shapes of the guided PL differed depending on the fiber diameter because of leakage of light into the substrate. We propose a model that reproduces the PL attenuation with increasing propagation lengths and includes the temporal PL decay due to photobleaching and the size of the excitation area. The calculated propagation loss coefficient in the fibers was 6.3 × 10^?3?1.4 × 10^?1 µm^?1 with λ = 430–500 nm. The propagation loss was inherent in the fiber itself because the re‐absorption loss coefficient of the doped dye was <1.3% of the propagation loss coefficient. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1237–1244     

Synthesis and characterization of a new phenanthrenequinoxaline‐based polymer for organic solar cells

Two donor–acceptor (D‐A) conjugated polymers, PQx and PphQx, composed of alkylthienyl‐substituted benzo[1,2‐b:4,5‐b']dithiophene (BDTT) as the electron donor and the new electron acceptors quinoxaline (Qx) or phenanthrenequinoxaline (phQx), were synthesized with Stille cross‐coupling reactions. The number‐averaged molecular weights (M_n) of PQx and PphQx were found to be 25.1 and 23.2 kDa, respectively, with a dispersity of 2.6. The band‐gap energies of PQx and PphQx are 1.82 and 1.75 eV, respectively. These results indicate that, because phQx units have highly planar structures, their inclusion in D‐A polymers will be a very effective method for increasing the polymers' effective conjugation lengths. The hole mobilities of PQx and PphQx were determined to be 5.0 × 10^?5 and 2.2 × 10^?4 cm² V^?1 s^?1, respectively. A polymer solar cell device prepared with PphQx as the active layer was found to exhibit a power conversion efficiency (PCE) of 5.03%; thus, the introduction of phQx units enhanced both the short circuit current density and PCE of the device. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2804–2810     

Synthesis and FET characterization of novel ambipolar and low‐bandgap naphthalene‐diimide‐based semiconducting polymers

A novel series of naphthalene‐diimide‐based semiconducting polymers ( P1–P4 ) containing benzodithiophene or dithienopyrrole were successfully synthesized for ambipolar semiconducting materials showing near infrared absorptions. The incorporation of a 3‐hexylthiophene (3HT) spacer extended the intramolecular charge‐transfer (ICT) peak from λ_onset = 739 nm ( P1 ) to 785 nm ( P3 ). Moreover, about 250 nm red‐shift of the ICT peaks was observed in P2 and P4 compared to P1 and P3 due to the increased high‐lying HOMO energy levels. The grazing incidence X‐ray scattering of the P3 and P4 films proved the slightly improved crystalline order in the π?π stacking direction, indicating that the planar backbone is probably due to the introduced 3HT. The P1–P4 ‐based field‐effect transistor showed n‐type dominant ambipolar characteristics. The P2 and P4 showed higher electron mobilities up to 1.5 × 10^?2 cm² V^?1 s^?1 than P1 and P3 , which might be influenced by the orientation of the polymer backbone and the intermolecular orbital overlap. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 359–367     

Electrosynthesis and electrochromic properties of free‐standing copolymer based on oligo(oxyethylene) cross‐linked 2,2’‐bithiophene and 3,4‐ethylenedioxythiophene

Oligo(oxyethylene) chains cross‐linked 2,2’‐bithiophene (BT‐E5‐BT) has been synthesized successfully. A free‐standing copolymer film based on BT‐E5‐BT and 3,4‐ethylenedioxythiophene (P(BT‐E5‐BT‐co‐EDOT)) has been synthesized by electrochemical polymerization. The electrical conductivity of P(BT‐E5‐BT‐co‐EDOT) copolymer (16 S m^?1) has improved by four orders of magnitude compared to the homopolymer of BT‐E5‐BT (P(BT‐E5‐BT), 5 × 10^?3 S m^?1) at room temperature. Both homopolymer and copolymer films exhibit well‐defined redox and satisfied coloration efficiency. Spectroelectrochemistry studies indicate that the P(BT‐E5‐BT‐co‐EDOT) has a lower band gap in the range of 1.83–1.90 eV and shows more plentiful electrochromic colours (green, blue, purple and salmon pink) compared with the homopolymer P(BT‐E5‐BT). The Copolymer P(BT‐E5‐BT‐co‐EDOT) shows the moderate optical contrast (26% of 480 nm) and coloration efficiency (205.41 cm^?1 C^?2). The copolymer method provides a novel way to fabricate a free‐standing organic electrochromic device. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1583–1592     

Synthesis and self‐assembling of poly(N‐isopropylacrylamide‐block‐poly(L‐lactide)‐block‐poly(N‐isopropylacrylamide) triblock copolymers prepared by combination of ring‐opening polymerization and atom transfer radical polymerization

Novel thermo‐responsive poly(N‐isopropylacrylamide)‐block‐poly(l ‐lactide)‐block‐poly(N‐isopropylacylamide) (PNIPAAm‐b‐PLLA‐b‐PNIPAAm) triblock copolymers were successfully prepared by atom transfer radical polymerization of NIPAAm with Br‐PLLA‐Br macroinitiator, using a CuCl/tris(2‐dimethylaminoethyl) amine (Me₆TREN) complex as catalyst at 25 °C in a N,N‐dimethylformamide/water mixture. The molecular weight of the copolymers ranges from 18,000 to 38,000 g mol^?1, and the dispersity from 1.10 to 1.28. Micelles are formed by self‐assembly of copolymers in aqueous medium at room temperature, as evidenced by ¹H NMR, dynamic light scattering (DLS) and transmission electron microscopy (TEM). The critical micelle concentration determined by fluorescence spectroscopy ranges from 0.0077 to 0.016 mg mL^?1. ¹H NMR analysis in selective solvents confirmed the core‐shell structure of micelles. The copolymers exhibit a lower critical solution temperature (LCST) between 32.1 and 32.8 °C. The micelles are spherical in shape with a mean diameter between 31.4 and 83.3 nm, as determined by TEM and DLS. When the temperature is raised above the LCST, micelle size increases at high copolymer concentrations due to aggregation. In contrast, at low copolymer concentrations, decrease of micelle size is observed due to collapse of PNIPAAm chains. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3274–3283     

Acid‐labile,thermoresponsive (meth)acrylamide polymers with pendant cyclic acetal moieties

Acid‐labile, thermoresponsive polymers with pendant six‐membered cyclic acetal groups were prepared by radical polymerization of two monomers, N‐(2,2‐dimethyl‐1,3‐dioxan‐5‐yl) methacrylamide (NDMM) and N‐(2,2‐dimethyl‐1,3‐dioxan‐5‐yl) acrylamide (NDMA). The aqueous solution properties of the polymers, PNDMM and PNDMA, were studied by turbidimetry, ¹H NMR, fluorescence, and DSC measurements. It is found that both polymers show sensitive and reversible phase transitions with distinct lower critical solution temperatures (LCST). Below their LCSTs, there are still some polymer aggregates as evidenced by measurements of pyrene excitation spectra and urea effects on the cloud points (CP) of polymers. The salting effect of six inorganic sodium salts on the phase transition behavior of PNDMM was investigated by turbidimetric approach. The salting‐out to salting‐in effect is in the order of SO₄^2? > F^? > Cl^? > Br^? > I^? > SCN^?, following the Hofmeister's series. pH‐dependent hydrolysis of PNDMM and PNDMA was studied by turbidimetric and ¹H NMR methods. They are both pH‐sensitive and their hydrolysis rates significantly increase with decreasing pH value. The CP of PNDMM gradually increases with the acid‐triggered hydrolysis of the acetal groups and the hydrolyzed polymer with ～ 30% hydrolysis degree does not show thermally induced phase transition. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4332–4343, 2008     

Inspiration from Old Dyes: Tris(stilbene) Compounds as Potent Gram‐Positive Antibacterial Agents

Herein we describe the preparation and structure‐activity relationship studies on range of stilbene based compounds and their antibacterial activity. Two related compounds, each bearing carboxylic acid moieties, exhibit good activity against several bacterial strains, including methicillin‐resistant Staphylococcus aureus MRSA (ATCC 33592 and NCTC 10442). Compound 10 was most active against Moraxella catarrhalis with minimum inhibitory concentrations (MICs) of 0.12–0.25 μg mL^?1 and against Staphylococcus spp. with MICs ranging from 2–4 μg mL^?1. The derivative 17 showed increased activity with MICs of 0.06–0.25 μg mL^?1 against M. catarrhalis and 0.12–1 against Staphylococcus spp. This level of activity is similar to that reported for S. aureus for antibiotics, such as vancomycin, with MICs of ≤2.0 μg mL^?1 and clindamycin with MICs of ≤0.5 μg mL^?1. As an indicator of toxicity, 17 was tested for its ability to lyse sheep erythrocytes, and showed low haemolytic activity. Such results highlight the value of tris(stilbene) compounds as antibacterial agents providing suitable properties for further development.     

Spectrofluorimetric and Spectrophotometric Stability‐Indicating Methods for the Analysis of Veralipride in Presence of Its Degradants and in Spiked Human Plasma

Spectrofluorimetric and spectrophotometric stability‐indicating methods were developed and validated for analysis of veralipride (Ver) in presence of its hydrolytic and oxidative degradants. The spectrofluorimetric method was based on direct measurement of the intrinsic fluorescence of Ver at 366 nm after excitation at 299 nm using sodium lauryl sulfate (SLS) as micelle enhancer. The fluorescence intensity plot was linear over the concentration range 1.0–10.0 µg·mL^?1. The high sensitivity of the method allowed its successful application to the analysis of Ver in spiked human plasma. Two other methods were developed. They are based on the oxidative coupling reaction of Ver with 3‐methyl benzothiazolin‐2‐one hydrazone (MBTH) hydrochloride in presence of ceric ammonium sulphate in an acidic medium. The first method depends on spectrophotometric measurement of the stable green colored oxidative coupling product at 660 nm. The different experimental parameters affecting the reaction were optimized. Linearity range is 10.0–100.0 µg·mL^?1. The second method depends on a fluorescence quenching effect of Ver on the fluorescence of Ce³⁺. The difference in fluorescence intensity was measured at 380 nm after excitation at 300 nm. This method is applicable over the concentration ranges 0.25–2.50 µg·mL^?1. The methods were validated according to the ICH guidelines. They were successfully applied for the analysis of Ver in drug substance, drug product and in laboratory prepared mixtures containing different percentages of hydrolytic and oxidative degradants.