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International audience; Two series of new dicationic stilbazolium salts containing tosylate and triflimide counterions, respectively, were synthesized and characterized by spectroscopic techniques and elemental analysis. Despite of their promesogenic structures, none of these salts are mesomorphous, and instead they solely exhibit crystalline polymorphism, as deduced from differential scanning calorimetry, polarizing optical microscopy and variable temperature X-ray measurements. These salts were also found to be highly thermally stable with decomposition temperatures occurring well above 300 °C, and up to 367 °C for the triflimide salts, as determined by thermogravimetric analysis. UV–Vis absorption and photoluminescent properties were examined in both solution and in the solid state. They exhibited higher absolute quantum yields in the powdered state than in solution. The dielectric response was evaluated by impedance spectroscopy, revealing notable values of short-range conductivity in triflimide salts through amorphous regions. Our work demonstrates the potential of these new stilbazolium salts as advanced materials in optoelectronic devices, with performances that can be tailored by molecular design of the spacer’s flexibility and choice of counter anions.

Safe and inexpensive methods for synthesis of a series of four substituted 2,4,6-triphenylyrylium tosylate salts with different substituents are reported. The synthesis methods use p-toluenesulfonic acid monohydrate instead of conventional acid catalysts including perchloric acid or boron trifluoride diethyl etherate that pose explosion danger and difficult storage problems, respectively. The chemical structures of these salts were established using FTIR, 1H and 13C NMR spectroscopic techniques and elemental analysis. Thermogravimetric analysis (TGA) showed that these salts have good thermal stability, and differential scanning calorimetry (DSC) analysis showed that they have lower melting transitions than the corresponding tetrafluoroborate and perchlorate salts. Solutions of the salts in organic solvents (such as acetonitrile and methanol) absorbed strongly in the blue-near-ultraviolet spectral range and emitted efficiently in the blue-green spectral range depending on the substituents in 2- and 6-positions of phenyl groups. The fluorescence quantum yields of the salts ranged from 0.33 to 0.56. Under intense ultrashort laser pumping, an acetonitrile solution of the salt, 2,4,6-triphenylpyrylium tosylate, the salt with the highest quantum yield, demonstrated stimulated emission and laser action with only nominal feedback.

Monomeric dialkyl and monoalkyl viologens rapidly catalyze O2-oxidation of carbohydrates in alkaline solution to form carbonate and formate at pH >11. Optimization of these catalytic reactions is important for alkaline carbohydrate fuel cell applications. Use of these monomeric viologens is not optimal because they exit the fuel cell with the reaction products and would need to be recovered and recycled for continued use. Polymeric or immobilized viologens would reduce or avoid these recovery problems. Here, we report the evaluation of water-soluble polymeric viologens as potential fuel-cell-catalysts and show that they rapidly catalyze O2-oxidation of carbohydrates to carbonate and formate at high efficiency. The rates of reduction of polymeric viologens by carbohydrates were rapid and found to be first order in carbohydrate and one-half order in polymer concentration. An unusual feature of the reduction reaction is that the rate of polymer reduction is two-fold faster if carbohydrate is equilibrated with the buffer prior to addition of the catalyst rather than adding the carbohydrate in the presence of the catalyst. Advantages and disadvantages of polymeric viologens as fuel cell catalysts are discussed.

A series of extended, symmetric viologen triflimides were synthesised by the metathesis reaction of lithium triflimide with the respective viologen tosyalates in methanol. Their chemical structures were characterised by Fourier Transform Infrared, 1H and 13C Nuclear Magnetic Resonance spectroscopy and elemental analysis. Their thermotropic liquid-crystalline (LC) properties were examined by a number of experimental techniques including differential scanning calorimetry, thermogravimetric analysis, polarising optical microscopy and variable temperature X-ray diffraction. The viologen salts containing alkyl chain of two carbon and three carbon atoms were relatively low melting salts. Those of alkyl chains of four carbon and five carbon atoms formed ionic liquids at 88 and 42°C, respectively. Those of alkyl chain of 9, 10 and 11 carbon atoms were high melting salts, as high as 166°C. Those of higher alkyl chains of 16, 18 and 20 carbon atoms showed thermotropic LC phases forming SmC, SmA and an unidentified smectic (SmX) phases, and showed SmA to isotropic transitions at high temperatures. As expected, all the viologen triflimides had excellent stabilities in the temperature range of 338–365°C.

Six new rugged, high-temperature tolerant phosphine oxide-containing poly(4,4&prime, (p-phenylene)-bis(2,6-diphenylpyridinium)) polymers P-1, P-2, P-3, P-4, P-5, and P-6 are synthesized, characterized, and evaluated. Synthesis results in high yield and purity, as confirmed by elemental, proton (1H), and carbon 13 (13C) nuclear magnetic resonance (NMR) spectra analyses. High glass transition temperatures (Tg &gt, 230 &deg, C) and high char yields (&gt, 50% at 700 &deg, C) are determined by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. These new ionic polymers exhibit excellent processability, thin-film forming, high-temperature resistance, fire-resistance and retardation, coating, adhesion, mechanical and tensile strength, and n-type (electron transport) properties. The incorporation of phosphine oxide and bis(phenylpyridinium) moieties in the polymer backbones leads to high glass transition temperatures and excellent fire retardant properties, as determined by microcalorimetry measurements. The use of organic counterions allows these ionic polymers to be easily processable from several common organic solvents. A large variety of these polymers can be synthesized by utilizing structural variants of the bispyrylium salt, phosphine oxide containing diamine, and the counterion in a combinatorial fashion. These results make them very attractive for a number of applications, including as coating and structural component materials for automobiles, aircrafts, power and propulsion systems, firefighter garments, printed circuit boards, cabinets and housings for electronic and electrical components, construction materials, mattresses, carpets, upholstery and furniture, and paper-thin coatings for protecting important paper documents.

A set of poly(pyridinium) salts containing various diamine moieties, as molecular connectors, and poly(ethyleneglycol)-4-nonylphenyl-3-sulfopropyl ether, thereafter referred to as &ldquo, Macroion&rdquo, as the hydrophilic counterion, were prepared by metathesis reaction from the respective precursory tosylated poly(pyridinium)s in methanol. The structure of these ionic polymers was established by spectroscopy and chromatography techniques. The shape-persistent ionic poly(pyridinium) materials, inserting rigid or semi-rigid diamine spacers, display thermotropic liquid-crystalline properties from room-temperature up to their isotropization (in the temperature range around 160&ndash, 200 &deg, C). The nature of the LC phases is lamellar in both cases as identified by the combination of various complementary experimental techniques including DSC, POM and variable-temperature SAXS. The other polymers, inserting bulky or flexible spacers, only form room temperature viscous liquids. These new macromolecular systems can then be referred to as polymeric ionic liquid crystals (PILCs) and or polymeric ionic liquids (PILs). All the ionic polymers show excellent thermal stability, in the 260&ndash, 330 &deg, C temperature range as determined by TGA measurements, and a good solubility in common organic solvents as well as in water. Their optical properties were characterized in both solution and solid states by UV&minus, Vis and photoluminescent spectroscopies. They emit blue or green light in both the states and exhibit a positive solvatochromic effect.

A series of asymmetric viologen bistriflimide salts of both short and long alkyl chains were synthesized by the metathesis reaction of lithium triflimide salt with the respective asymmetric viologen dibromide salts in methanol. Their thermotropic liquid crystalline properties were determined by differential scanning calorimetry, polarizing optical microscopy and variable temperature X-ray diffraction techniques. These salts melt into highly-ordered smectic T phases that is, crystal-to SmT transitions (Tms) at relatively low temperatures (lowest Tm at −12 °C) and maintain liquid crystallinity in a wide range of temperatures (8–132 °C), with excellent thermal stabilities up to 320 °C as determined by thermogravimetric analysis. These results differ with respect to the symmetric viologen bistriflimide salts. Ionic conductivity of these salts was also measured by dielectric impedance spectroscopy and found to be in the 10−2.5 S cm−1 range, highlighting their potential as electrolytes at room temperature.

A series of poly(pyridinium salt)s-fluorene main-chain ionic polymers with various organic counterions were synthesized by using ring-transmutation polymerization and metathesis reactions. Their chemical structures were characterized by Fourier Transform Infrared (FTIR), proton (1H), and fluorine 19 (19F) nuclear magnetic resonance (NMR) spectrometers. These polymers showed a number-average molecular weight (Mns) between 96.5 and 107.8 kg/mol and polydispersity index (PDI) in the range of 1.12–1.88. They exhibited fully-grown lyotropic phases in polar protic and aprotic solvents at different critical concentrations. Small-angle X-ray scattering for one polymer example indicates lyotropic structure formation for 60–80% solvent fraction. A lyotropic smectic phase contains 10 nm polymer platelets connected by tie molecules. The structure also incorporates a square packing motif within platelets. Thermal properties of polymers were affected by the size of counterions as determined by differential scanning calorimetry and thermogravimetric analysis measurements. Their ultraviolet-visible (UV-Vis) absorption spectra in different organic solvents were essentially identical, indicating that the closely spaced π-π* transitions occurred in their conjugated polymer structures. In contrast, the emission spectra of polymers exhibited a positive solvatochromism on changing the polarity of solvents. They emitted green lights in both polar and nonpolar organic solvents and showed blue light in the film-states, but their λem peaks were dependent on the size of the counterions. They formed aggregates in polar aprotic and protic solvents with the addition of water (v/v, 0%–90%), and their λem peaks were blue shifted.

A series of bis(4-alkoxyphenyl) viologen bis(triflimide) salts with alkoxy chains of different lengths were synthesized by the metathesis reaction of respective bis(4-alkoxyphenyl) viologen dichloride salts, which were in turn prepared from the reaction of Zincke salt with the corresponding 4-n-alkoxyanilines, with lithium triflimide in methanol. Their chemical structures were characterized by 1H and 13C nuclear magnetic resonance spectra and elemental analysis. Their thermotropic liquid-crystalline (LC) properties were examined by differential scanning calorimetry, polarizing optical microscopy, and variable temperature X-ray diffraction. Salts with short length alkoxy chains had crystal-to-liquid transitions. Salts of intermediate length alkoxy chains showed both crystal-to-smectic A (SmA) transitions, Tms, and SmA-to-isotropic transitions, Tis. Those with longer length of alkoxy chains had relatively low Tms at which they formed the SmA phases that persisted up to the decomposition at high temperatures. As expected, all of them had excellent thermal stabilities in the temperature range of 330&ndash, 370 &deg, C. Their light-emitting properties in methanol were also included.

A group of five 2,4,6-tris(4-substituted phenyl)pyrylium tosylates were synthesized in one-pot reaction from para-substituted benzaldehyde and para-substituted acetophenones using tosic acid as a condensing agent. The tosylate salts were converted to the corresponding triflimide salts by metathesis reactions. Chemical structures, as well as optical spectroscopic and thermal properties of these salts were studied using pertinent experimental techniques. Trimethyl- and trihalo-substituted pyrylium salts emitted strong blue light with peaks in the 456 nm–479 nm range and trimethoxy-pyrylium salts emitted intense green light with maxima around 526 nm in acetonitrile solution. Quantum yields of the solutions were rather low, but the salts were also fluorescent in the solid state. Acetonitrile solution of trichloro-substituted pyrylium triflimide showed significant spectral line narrowing and fluorescence lifetime shortening under intense excitation, and laser action with minimal feedback. The salts have low melting transitions compared to the corresponding –BF4 salts, and their thermal stability is excellent with decomposition temperature in the 268–402 °C range in nitrogen.

Thermotropic properties of catanionic surfactants are influenced by the headgroups as well as hydrocarbon chains. A series of eight catanionic surfactants were synthesized from quaternary ammonium surfactants as the cationic counterpart and dodecylbenzenesulfonate (DBS) as the anionic counterpart and their structures and purities established. Thermal Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Hot-Stage Polarized Light Microscopy (HSPLM), and X-ray Diffraction (XRD) were used to characterize the thermal and liquid crystalline properties of the derived catanionic surfactants. These surfactants form hexagonal columnar (Col h ) phase before isotropization. Their phase behavior is rather complex depending on the chain length, symmetry, and number of chains. In all these surfactants, the thermal stability is influenced by the nature of the headgroup. Mesomorphism on the other hand is a result of the interplay between headgroup interactions and chain interactions. In general, formation of mesophases at lower temperature is favored as the number of CH 2 groups per molecule is increased.

A new class of bisquinoline diamines prepared by Friedlander condensation reaction are reported showing stable amorphous state with high glass transition temperatures up to 150 °C and high thermal stabilities >370 °C. Additionally, they show excellent fluorescent properties in the blue, green and yellow region of visible light in both solution and solid states. They show narrow full-widths at half-maxima in the range of 52–73 nm in various organic solvents. Their solution quantum efficiencies are relatively high in the range of 27–38%. The absorption spectra obtained from time-dependent density functional theory (TDDFT) using optimized geometry correlated well with the experimental data. From the frontier molecular orbital studies, the electronic transitions involved possesses π–π* character. These materials could be useful for high-performance applications in opto- and microelectronic fields either by further chemical transformations of these diamines for amorphous molecular materials or by their polymerization reactions to create charge transporting materials.

Hypothesis Properties of catanionic surfactants can be tailored by the choice of appropriate headgroups and hydrocarbon tails. Thermal behavior of catanionic surfactants can be influenced by the length and number of alkyl chains. Experiments A series of eight catanionic surfactants were synthesized from quaternary ammonium surfactants as the cationic counterpart and bis(2-ethylhexyl)sulfosuccinate (AOT) as the anionic counterpart. The thermal properties and the liquid crystalline properties of these catanionic surfactants were studied by the following methods: Thermal Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Hot-Stage Polarized Light Microscopy (HSPLM), and X-ray Diffraction (XRD). Findings The results indicate that transition temperatures, enthalpies of transition, and mesophase structures vary with the length and number of chains attached to the quaternary nitrogen. These compounds exhibit room temperature liquid crystalline (LC) textures that are predominantly “fan-like,” as observed by HSPLM, and phases that are hexagonal columnar, as observed by XRD, with the exception of one compound which exists as a nematic liquid crystal at 25 °C. Additionally, all of the surfactants also exhibit thermal stability in the range of 256–300 °C.

Bis(pyridinium salt)s containing different alkyl chain lengths and various organic counterions were prepared by the ring-transmutation reaction of bis(pyrylium tosylate) with aliphatic amines in dimethyl sulfoxide at 130–135 °C for 18 h and their tosylate counterions were exchanged to other anions such as triflimide, methyl orange, and dioctyl sulfosuccinate by the metathesis reaction in a common organic solvent. Their chemical structures were established by using 1H, 19F, and 13C NMR spectra. The thermal properties of bis(pyridinium salt)s were studied by DSC and TGA measurements. Some of the dicationic salts provided low melting points below 100 °C and some of them displayed amorphous properties. Polarized optical microscopy studies revealed the crystal structures prior to melting temperatures in some cases. Their optical properties were examined by using UV–Vis and photoluminescent spectrometers; and they emitted blue light both in the solution and solid states regardless of their microstructures, counterions, and the polarity of organic solvents. However, most of these salts exhibited hypsochromic shifts in their emission peaks in the solid state when compared with those of their solution spectra. Due to unique properties of methyl orange anion as a pH indicator, two of the salts showed different color change in varying concentrations of triflic acid in common organic solvents, demonstrating their potential use as an acid sensor in methanol, acetonitrile and acetone.

A series of luminescent tricationic salts having mesitylene and stilbazolium moieties with various organic counterions were synthesized by using quaternization and metathesis reactions. Their chemical structures were characterized by 1 H, 19 F and 13 C NMR spectroscopy, and elemental analysis. Their crystalline and amorphous properties were examined by differential scanning calorimetry, polarized optical microscopy, and variable-temperature X-ray diffraction studies. Their thermal stabilities were determined by thermogravimetric analyses, which were in the broad temperature ranges of 239–317 °C in nitrogen. Their optical properties were studied by UV–Vis and photoluminescent spectroscopy. The light-emission properties were dependent on the polarity of organic solvents (positive solvatochromism) but independent on the chemical structures of organic counterions. They emitted blue light in various organic solvents in a broad range of wavelengths of 470–497 nm, but emitted green light in a narrow range of wavelengths of 506–515 nm in their solid states.

Several poly(pyridinium salt)s containing various aromatic diamine moieties and tosylate counterions were prepared by the ring-transmutation polymerization reaction of bis(pyrylium tosylate) with aromatic diamines in dimethyl sulfoxide at 130−135 °C for 48 h and their tosylate counterions were exchanged to triflimide polymers by a metatheses reaction in an organic solvent. Their chemical structures were established by using various spectroscopic techniques. Their number-average molecular weights (Mn) were in the range of 38–46 kg/mol and polydispersities in the range of 1.13–1.43 as determined by gel permeation chromatography. They showed excellent thermal stabilities in nitrogen in the range of 326–477 °C. They exhibited lyotropic liquid-crystalline phase in polar aprotic and protic organic solvents above their critical concentrations depending on their microstructures and counterions. Their optical properties were examined by using UV–Vis and photoluminescent spectroscopy, which revealed that some polymers emitted UV light, some emitted blue light, and some emitted green light (both in solutions and solid states) depending on their microstructures, counterions, and on solvent polarity of organic solvents.

Several new poly(pyridinium salt)s with quinoline diamine moieties in their backbones with tosylate and triflimide counterion were prepared by either a ring-transmutation polymerization reaction with bis(pyrylium tosylate) with a series of isomeric quinoline diamines in dimethyl sulfoxide (DMSO) for 48 h at 130–140 °C or a metathesis reaction of the tosylate polymers with lithium triflimide in DMSO at about 60 °C. Their chemical structures were confirmed by FTIR, 1H and 13C NMR spectroscopy, and elemental analysis. Their number-average molecular weights (Mn) were in the range of 18,000–58,000, and their polydispersities were in the range of 1.12–1.53 as determined by gel permeation chromatography. They had thermal stability in the temperature range of 353–455 °C and glass-transition temperatures >240 °C. They had good solubility in common organic solvents and were characterized with polarizing optical microscopy (POM) studies for their lyotropic liquid-crystalline properties. Their light-emission properties were examined by spectrofluorometry in both the solution and film states. Their quantum yields were also determined. Additionally, their morphologies in the thin-film states and melt-drawn fibers were examined with POM, scanning electron microscopy, and transmission electron microscopy techniques. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

A new class of conjugated quinoline amines was prepared by Friedlander condensation reaction. They showed stable amorphous state below glass transition temperatures as examined by differential scanning calorimetry and X-ray diffraction studies. Additionally, they exhibited fluorescence properties in the blue to green region of visible spectrum in both solution and solid state. Their fluorescence quantum efficiencies in chloroform were in a broad range of 3–45%. Interestingly, they formed stable fibers with micrometer thickness drawn from melt, which were characterized by polarizing optical microscopy and scanning electron microscopy studies.

Several novel poly(pyridinium salt)s with heterocy- clic pyridine moieties in their backbones with tosylate and trifli- mide counterions were prepared by either ring-transmutation polymerization reaction of phenylated-bis(pyrylium tosylate) with isomeric pyridine diamines of 4-phenyl-2,6-bis(4-amino- phenyl)pyridine in dimethyl sulfoxide (DMSO) for 48 h at 130- 140 � C or by metathesis reaction of the respective tosylate polymers with lithium triflimide in DMSO at about 60 � C. Their chemical structures were characterized by FTIR, 1 H, 13 C NMR spectroscopy, and elemental analysis. Their number-average molecular weights (Mn) were in the range of 8,000-51,000 and their polydispersities in the range of 1.18-2.13 as determined by gel permeation chromatography. They had excellent ther- mal stabilities of 340-458 � C and high glass transition tempera- tures >200 � C. As they showed good solubilities in common organic solvents, their solution properties were also character- ized for their lyotropic liquid-crystalline properties with polariz- ing optical microscopy (POM) studies. Their photoluminescent properties were examined by using a spectrofluorometer in both solution and solid states. Their quantum yields were rather low, which were in the range of 1.3-2.0%. Additionally, hand-drawn fibers from the melts were examined to determine their morphologies with a number of microscopic techniques including POM, scanning electron microscopy, and transmis- sion electron microscopy. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4408-4418, 2010

A series of azomethine dimers were prepared by condensation reactions of benzaldehyde, biphenylcarboxaldehyde and 9-anthraldehyde with various aromatic diamines of varying flexibility in ethanol in the presence of tosic acid. Their chemical structures were determined by Fourier transform infrared and 1H and 13C nuclear magnetic resonance (NMR) spectroscopies, as well as elemental analysis. Their thermal properties were also examined by using a number of experimental techniques, including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), polarising optical microscopy (POM) and variable temperature X-ray diffraction (VTXRD). Azomethine dimer, prepared from benzaldehyde and 1,9-bis(4-aminophenoxy)nonane, exhibited a monotropic, nematic liquid-crystalline (LC) phase. The majority of the azomethine dimers containing biphenyl moieties exhibited enantiotropic, nematic LC phase on melting at relatively low temperatures, since they developed typical Schlieren, threaded or marbled textures ...

Several poly(pyridinium salt)s containing various organic counterions and oxyethylene unit in their backbones were synthesized by either the ring-transmutation polymerization reaction of 4,4′-(1,4-phenylene)bis(2,6-diphenylpyrylium tosylate) with 1,2-bis(4-aminophenoxy)ethane on heating in dimethyl sulfoxide or the metathesis reaction of the tosylate polymer with the corresponding lithium or sodium salts in acetonitrile. Their chemical structures were determined by 1H and 13C NMR spectroscopy, and elemental analyses. Their number-average molecular weights and polydispersity indices were in the range of 59,000–63,000 and 1.41–1.65, respectively, as determined by gel permeation chromatography. They were characterized for their thermotropic and lyotropic liquid-crystalline properties by using differential scanning calorimetry and polarizing optical microscopy. Since these polymers exhibited liquid-crystalline phase both in the melt and in solutions, they belong to an amphotropic class of ionic polymers. Their light-emitting properties both in polar organic solvents and in films cast from methanol and acetonitrile were also studied by using spectrofluorometry.

The interaction of a main-chain viologen polymer containing bromide as counterions with water and aqueous potassium bromide over a broad range of concentrations was studied with isothermal titration calorimetry. The dilution process of this polymer was endothermic as opposed to flexible poly(sodium acrylate) and poly(sodium styrenesulfonate). This result may be related to the different mechanism of hydration of pyridinium and bromide groups in the main chain. It also exhibited aggregation phenomenon in both water and aqueous potassium bromide solutions as detected by transmission electron microscopy like other flexible and rigid-rod polyelectrolytes. As the polymer concentrations in aqueous solutions increase, the aggregated polymer exhibited more defined ordered structures than random structures observed at low polymer concentrations. Field emission scanning electron microscopy also revealed the effect of variation of concentration of aqueous potassium bromide on the morphology of the polymer matrix. At increasing concentrations of aqueous potassium bromide, the polymer structures became more ordered than those in low concentrations.

Several anthracene derivatives were prepared by a single-step reaction and characterized their thermal properties by differential scanning calorimetry (DSC) and thermogravimetric analyses. Their photoluminescence properties were examined in a large number of organic solvents of increased polarity that included toluene, chloroform, tetrahydrofuran, acetone, methanol, acetonitrile, and dimethyl sulfoxide. Some compounds exhibited emission spectra with vibrational fine structures in organic solvents; and other compounds exhibited structureless emission spectra in organic solvents.

Several novel poly(pyridinium salt)s with oxyalkylene moieties in the main chain with bulky organic counterions (tosylate and triflimide) were prepared by either the ring-transmutation polymerization of phenylated bis(pyrylium tosylate) salt with a series of oxyalkylene containing diamines in dimethyl sulfoxide on heating for 48 h or the metathesis reaction of the corresponding tosylate polymers with lithium triflimide in methanol. Their chemical structures were determined by elemental analysis and 1H and 13C NMR spectroscopies, and their polyelectrolyte behavior in dimethyl sulfoxide was determined by solution viscosity measurements. Their weight average molecular weights were in the range 14,000–22,000 and polydispersity indices were in the range 1.20–1.70 as determined by gel permeation chromatography. They were characterized both for their thermotropic and lyotropic liquid–crystalline properties by using differential scanning calorimetry and polarizing optical microscopy. Since these polymers exhibited liquid–crystalline phase both in the melt and in solution, they can be appropriately classified as amphotropic class of ionic polymers. Their light-emitting properties were also determined by using spectrofluorometry.

A series of 4,4ʹ-dialkoxy-3,3ʹ-diaminobiphenyl compounds were synthesised by three-step procedure that involves alkylation, nitration and reduction reactions. Their chemical structures were characterised by FTIR, 1H and 13C spectroscopy and elemental analysis. Their thermotropic liquid–crystalline (LC) properties were examined by a number of experimental techniques including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), polarising optical microscopy (POM) and variable temperature X-ray diffraction (VT-XRD). The 4,4ʹ-dialkoxy-3,3ʹ-dinitrobipheyl compounds, precursors to the diamine compounds, were also examined for their thermotropic LC properties. POM studies of focal conic textures and VT-XRD of the 3,3ʹ-diaminobiphenyl derivatives having flexible alkyl chains (C6–C12) exhibited the smectic A (SmA) phase independent of the length of alkyl chains. Similarly, the 3,3ʹ-dinitrobiphenyl derivatives containing alkyl chains C7, and C9–C11 exhibit the SmA phase, those containing C8 formed the smectic C (SmC) phase and C12 formed both the SmA and smectic B (SmB) phases, respectively. The 3,3ʹ-diaminobiphenyl derivatives had excellent thermal stability in the temperature range of 237–329°C, while those of 3,3ʹ-dinitrobiphenyl derivatives were in the temperature range of 270–321°C. The 3,3ʹ-diaminobiphenyl derivatives emitted UV light both in chloroform and acetonitrile.

A series of conjugated, bispyridyl and tetrapyridyl compounds were synthesized from either terephthalaldehyde or isophthalaldehyde and activated pyridyl compounds by Knoevenagel reaction on heating in acetic anhydride in presence of acetic acid and their optical and thermal properties were examined. All of them exhibited photoluminescence in chloroform, tetrahydrofuran, and dimethyl sulfoxide as well as in solid state. In solid state, their emission spectra exhibited bathochromic shifts when compared with those in less or more polar solvents. Some compounds emitted UV light both in polar solvents and in the solid state; other compounds emitted UV light in polar solvents, but emitted visible light in the solid state.

A series of main chain, thermotropic, liquid crystalline (LC) hydrogen‐bonded polymers based on 4,4′‐bipyridyl as a hydrogen bond acceptor and 4,4′‐dicarboxy‐α,ω‐diphenoxyalkanes as hydrogen bond donors were prepared by a slow evaporation technique from a pyridine solution and characterized for their thermotropic LC properties using a variety of experimental techniques. The homopolymer of 4,4′‐bipyridyl with 4,4′‐dicarboxy‐1,9‐diphenoxynonane exhibited relatively low T m at 205°C and low T i at 230°C, giving an LC phase range of 25°C. The other two homopolymers with 4,4′‐dicarboxy‐1,6‐diphenoxyhexane and 4,4′‐dicarboxy‐1,9‐diphenoxydecane exhibited relative low T m values, above which each of them formed high‐order smectic phases. With further heating at higher temperature they transformed into low‐order smectic phases that persisted up to their decomposition temperatures. Several copolymers also had relatively low T m values as well as low T i values and, therefore, had a broad LC phase range (22–77°C). ...

Two poly(pyridinium salt)s with anthracene moieties in the main chain as well as tosylate and triflimide as counterions were prepared by either the ring-transmutation polymerization of phenylated bis(pyrylium tosylate) salt with 2,6-diaminoanthracene in dimethyl sulfoxide or the metathesis reaction of the corresponding tosylate polymer with lithium triflimide in acetonitrile. They were characterized for their lyotropic liquid-crystalline and UV light-emitting properties, with various experimental techniques. These ionic, conjugated anthracene polymers are the recent addition to the class of UV light-emitting polymers, since they emit UV light both in solution and in the solid state.

Several viologen bis{tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate} salts were prepared by metathesis reaction of the corresponding viologen dibromides (diiodide) with sodium bis{tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate} salt in a polar organic solvent. They were characterized for their physical and thermal properties by experimental techniques including variable temperature X‐ray diffraction. All exhibited low T g and T m, and their T g/T m (K) ratios were in the range 0.66–0.79. Several exhibited polymorphism and formed isotropic ionic melts at

Two poly(pyridinium salt)s with bulky organic counterions (tosylate and triflimide) were synthesized by either the ring-transmutation polymerization reaction of 4,4‘-(1,4-phenylene)bis(2,6-diphenyl...

Two poly(pyridinium salt)s with bulky organic counterions (tosylate and triflimide) were synthesized by either the ring-transmutation polymerization reaction of 4,4'-(1,4-phenylene)bis(2,6-diphenylpyrylium tosylate) with 1,12-diaminododecane on heating in dimethyl sulfoxide (DMSO) at 145-150 °C for 24 h or the metathesis reaction of the corresponding tosylate polymer with lithium triflimide in a common organic solvent such as acetonitrile. Their polyelectrolyte behavior in DMSO was determined by solution viscosity measurements, and their chemical structures were determined by Fourier transform infrared and Fourier transform NMR spectroscopy. They were characterized for their thermotropic liquid-crystalline properties with a number of experimental techniques. Poly(pyridinium salt) with tosylate as a counterion had a crystal-to-smectic phase transition at 116 °C that persisted up to its decomposition temperature. The corresponding polymer with triflimide as a counterion had not only lower crystal-to-smectic phase transition at 80 °C but also a smectic-to-isotropic transition at about 180 °C. Both of these transitions were well below its decomposition temperature. It had better thermal stability than that of the corresponding tosylate polymer. Their fluorescence property in solutions of tetrahydrofuran and methanol as well as in the solid state was also included in this study.

Several dicationic salts with bis(triflimide) as counterions—otherwise known as viologens—were prepared by metathesis reaction of the corresponding viologen dibromides (diiodides) with lithium triflimide in a polar solvent. They were characterized for their thermotropic liquid-crystalline properties with various experimental techniques. Two of them had low crystal-to-smectic phase transitions (Tm) at –4 and 28°C; the other two also had low Tm values, at 51 and 58°C. Each had a wide range of LC phase. Two had relatively low crystal-to-isotropic (Tm) transitions at 117 and 131°C. Each had excellent thermal stability in the temperature range of 327–396°C. They exhibited photoluminescence property in both nonpolar and polar solvents as well as in the solid state. Their emission spectra in the solid state exhibited hypsochromic shift when compared with those in solution of dimethoxyethane.

Two dicationic salts with bis(triflimide) as counterions exhibited crystal-to-smectic liquid crystalline phase transitions (T m=41 and 37°C) and smectic-to-isotropic liquid phase transitions (T i=112, 136°C). They had a broad liquid crystalline phase range (71–99°C) and an excellent range of thermal stability (360–364°C). Their mixtures of various compositions also displayed liquid crystalline properties from r.t. to an extended range of temperatures. They exhibited fluorescence in 1, 2-dimethoxyethane and methanol.

A series of main-chain, thermotropic, liquid-crystalline (LC), hydrogen-bonded polymers or self-assembled structures based on 4,4'-bipyridyl as a hydrogen-bond acceptor and aliphatic dicarboxylic acids, such as adipic and sebacic acids, as hydrogen-bond donors were prepared by a slow evaporation technique from a pyridine solution and were characterized for their thermotropic, LC properties with a number of experimental techniques. The homopolymer of 4,4'-bipyridyl with adipic acid exhibited high-order and low-order smectic phases, and that with sebacic acid exhibited only a high-order smectic phase. Like the homopolymer with adipic acid, the two copolymers of 4,4'-bipyridyl with adipic and sebacic acids (75/25 and 25/75) also exhibited two types of smectic phases. In contrast, the copolymer of 4,4'-bipyridyl with adipic and sebacic acids (50/50), like the homopolymer with sebacic acid, exhibited only one high-order smectic phase. Each of them, including the copolymers, had a broad temperature range of LC phases (36-51 °C). The effect of copolymerization for these hydrogen-bonded polymers on the thermotropic properties was examined. Generally, copolymerization increased the temperature range of LC phases for these polymers, as expected, with a larger decrease in the crystal-to-LC transition than in the LC-to-isotropic transition. Additionally, it neither suppressed the formation of smectic phases nor promoted the formation of a nematic phase in these hydrogen-bonded polymers, as usually observed in many thermotropic LC polymers. The thermal transitions for all of them, measured by differential scanning calorimetry, were well below their decomposition temperatures, as measured by thermogravimetric analysis, which were in the temperature range of 193-210 °C.

A poly(pyridinium salt) was synthesized from 4,4′-(1,4-phenylene)bis(2,6-diphenylpyrilium)tosylate and 3,3′-dimethylnaphthidine. Tosylate counterion was exchanged with other organic counterions such as triflimide, 1-napthalenesulfonate, and 2-napthalenesulfonate in DMSO to yield a total of four poly(pyridinium salt)s. Their chemical structures were established by using various spectroscopic techniques. Gel permeation chromatography showed that their number-average molecular weights (Mn) were in the range of 56–76 kg/mol and polydispersities in the range of 1.09–1.32. Their thermal stabilities ranged from 290 to 425 °C, under nitrogen atmosphere. Even though these polymers didn’t show thermotropic liquid crystalline phases, counterion-dependent lyotropic liquid-crystalline phase were observed in some polar aprotic solvents above their critical concentrations. Each of these polymers emitted green light (500–572 nm) both in solutions and solid states as observed by UV–vis and photoluminescent spectroscopies.

The solution-phase behavior of three main-chain viologen polymers, which are composed of isomeric xylyl units and triflimide as a counterion, was studied in methanol, dimethylformamide, acetonitrile, and dimethyl sulfoxide as solvents microscopically under crossed polarizers. Each of them exhibited a lyotropic lamellar phase in both polar protic and aprotic solvents. Their C* for the formation of biphasic solutions (1-5 wt %) and concentrations (20-30 wt %) for the lyotropic solutions in methanol was much lower than those in polar aprotic solvents (20-71 and 60-81 wt %, respectively). Their high solubility, high C* for the formation of biphasic solutions, and high concentrations for the formation of lyotropic solutions in polar aprotic solvents were related to the significant reduction of strong ionic interactions between triflimide and 4,4'-bipyridinium ions in each of these viologen polymers. They were the first examples of viologen polymers that exhibited a lyotropic phase in polar aprotic solvents.

A series of viologen polymers with bromide, tosylate, and triflimide as counterions were prepared by either the Menshutkin reaction or metathesis reaction in a common organic solvent. Their polyelectrolyte behavior in methanol was determined by solution viscosity measurements, and their chemical structures were determined by Fourier transform infrared and Fourier transform NMR spectroscopy. They were characterized for their thermotropic liquid-crystalline properties with a number of experimental techniques. Each of the viologen polymers with organic counterions had a low melting transition or fusion temperature above which it formed either a high-order smectic phase or a low-order smectic phase. Each of them also exhibited a smectic-to-isotropic transition. The ranges of the liquid-crystalline phase were 80–88 °C for viologen polymers with tosylate as a counterion and 120–146 °C for viologen polymers with triflimide as a counterion. They had excellent thermal stability. The ranges of thermal stability were 288–329 °C for viologen polymers with tosylate as a counterion and 343–350 °C for viologen polymers with triflimide as a counterion. The fluorescence property for all of the viologen polymers in either aqueous or methanol solution was also included in this study. For example, the viologen polymer containing the 4,4′-bipyridinium and p-xylyl units along the backbone of the polymer chain with triflimide as a counterion had an absorption spectrum (λmax = 265 nm), an excitation spectrum (λex values = 357, 443, and 454 with monitoring at 533 nm), and an emission spectrum (λem = 536 nm with excitation at 430 and 450 nm) in methanol. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 659–674, 2002; DOI 10.1002/pola.10134

A series of thermotropic polyesters, derived from 4,4′-biphenol (BP), 3-phenyl-4,4′-biphenol (MPBP), and 3,3′-bis(phenyl)-4,4′-biphenol (DPBP), 4,4′-oxybisbenzoic acid (4,4′-OBBA), and other aromatic dicarboxylic acids as comonomers, were prepared by melt polycondensation and were characterized for their thermotropic liquid-crystalline (LC) properties with a variety of experimental techniques. The homopolymer of BP with 4,4′-OBBA and its copolymers with either 50 mol % terephthalic acid or 2,6-naphthalenedicarboxylic acid had relatively high values of the crystal-to-nematic transition (448–460 °C), above which each of them formed a nematic LC phase. In contrast, the homopolymers of MPBP and DPBP had low fusion temperatures and low isotropization temperatures and formed nematic melts above the fusion temperatures. Each of these two polymers also exhibited two glass-transition temperatures, which were associated with vitrified noncrystalline (amorphous) regions and vitrified LC domains, as obtained directly from melt polycondensation. As expected, they had higher glass-transition temperatures (176–211 °C) than other LC polyesters and had excellent thermal stability (516–567 °C). The fluorescence properties of the homopolymer of DPBP with 4,4′-OBBA, which was soluble in common organic solvents such as chloroform and tetrahydrofuran, were also included in this study. For example, it had an absorption spectrum (λmax = 259 and 292 nm), an excitation spectrum (λex = 258 and 292 nm with monitoring at 350 nm), and an emission spectrum (λem = 378 nm with excitation at 330 nm) in chloroform. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 141–155, 2002

A series of viologen polymers based on 4,4'-bipyridyl and the ditosylates of trans-1,4-cyclohexanedimethanol and 1,8-octanediol was prepared by the quaternization reaction in acetonitrile. Their polyelectrolyte behavior in a common organic solvent was studied by viscosity measurements, and their chemical structures were determined by FTIR and 1D and 2D NMR spectroscopies. They were characterized for their lyotropic properties in a number of polar organic solvents by polarizing light microscopy and differential scanning calorimetry and for their photochromic properties by UV-vis spectroscopy. As expected, their inherent viscosity in methanol decreased dramatically with the increase in concentration in the absence of an added electrolyte. Although each of these polymers contained the ionic group along the backbone of the polymer chain, there was an array of weak ion-pair dipoles between the tosylate ion and the 4,4'-bipyridinium ion in each of them, which was indicated by the appearance of symmetric stretching band of S=O at a lower frequency (1034 cm -1 ) when compared with that of -SO 3 Na (1064 cm -1 ) in its IR spectrum. The aromatic protons of 4,4'-bipyridinium ion in each of these polymers exhibited three pairs of signals as opposed to a pair of doublets that generally occurs in small molecules containing this ion. These three pairs of signals were related to the structure and dynamics of these ionic polymers in a polar solvent such as methanol, which were studied by DEPT, 1 H- 1 H COSY, and NOESY spectroscopies. Each of them showed a lyotropic lamellar phase in methanol, ethanol, ethylene glycol, diethylene glycol, glycerine, and benzyl alcohol. Their critical concentrations (C * values) were as low as 5 wt % and as high as 20-40 wt %, and their concentrations for the development of fully grown lyotropic phase were as low as 10-20 wt % and as high as 40-50 wt % in various alcohols depending on the polarity of the solvents, the hydrophilicity and hydrophobicity of the solvents, and the microstructures of these polymers. Additionally, their lyotropic solutions in either glycerine or benzyl alcohol, on irradiation with UV light, produced a deep blue color in the presence of air, but in absence of both a photosensitizer and a sacrificial donor. This deep blue solution had two absorption bands at 390 and 608 nm, which are the characteristic absorption bands of the viologen cation radical. The generation of this blue color occurred due to the photoreduction of the 4,4'-bipyridinium moiety via the electron transfer from the tosylate counterion.

A series of wholly aromatic, thermotropic polyesters, derived from 3,3′-bis(phenyl)-4,4′-biphenol (DPBP), nonlinear 4,4′-benzophenone dicarboxylic acid (4,4′-BDA), and various linear comonomers, were prepared by the melt polycondensation reaction and characterized for their thermotropic properties by a variety of experimental techniques. The homopolymer of DPBP with 4,4′-BDA had a fusion temperature (Tf) at 265°C, exhibited a nematic phase, and had a liquid crystalline range of 105°C. All of the copolyesters of DPBP with 4,4′-BDA and either 30 mol % 4-hydroxybenzoic acid (HBA), 6-hydroxy-2-naphthoic acid (HNA), or 50 mol % terephthalic acid (TA), 2,6-naphthalenedicarboxylic acid (2,6-NDA) had low Tf values in the range of 220–285°C, exhibited a nematic phase, and had accessible isotropization transitions (Ti) in the range of 270–420°C, respectively. Their accessible Ti values would enable one to observe a biphase structure. Each of the copolymers with HBA or HNA had a much broader range of liquid crystalline phase. In contrast, each of the copolymers with TA or 2,6-NDA had a relatively narrow range of liquid crystalline phase. Each of these polyesters had a glassy, nematic morphology that was confirmed with the DSC, PLM, WAXD, and SEM studies. As expected, they had higher glass transition temperatures (Tg) in the range of 161–217°C than those of other liquid crystalline polyesters, and excellent thermal stabilities (Td) in the range of 494–517°C, respectively. Despite their noncrystallinity, they were not soluble in common organic solvents with the exception that the homopolymer and its copolymer with TA had limited solubility in CHCl3. However, they were soluble in the usual mixture of p-chlorophenol/1,1,2,2-tetrachloroethane (60/40 by weight) with the exception of the copolymer with 2,6-NDA. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 769–785, 1997

A series of [Pt(II)Cl2(4,4'-dialkoxy-2,2'-bipyridine)] complexes of the general formula of [Pt(II)Cl2(4,4'-bis(RO)-2,2'-bipyridine)] (where R = -(CH2)n-1CH3, n = 2-6, 8) were synthesized and characterized using (1)H NMR, (13)C NMR spectroscopy, elemental analysis, mass spectroscopy, and differential scanning calorimetry measurements. The in vitro anti-proliferative activities of these compounds were evaluated against human cancer cell lines A549 (lung adenocarcinoma), DU145 (prostate carcinoma), MCF-7 (breast adenocarcinoma), and MDA-MB-435 (melanoma) using the MTS cell proliferation assay. Several Pt(II) coordination compounds were found to have greatly enhanced activity compared to cisplatin after a one hour treatment in all cell lines tested. A structure-activity relationship was observed, that is, the activity increases as the carbon chain length of the alkyl group increases. The activity was maximum when the carbon chain length reached four or five carbons and decreased with the longer carbon chain length. Fluorescence microscopy and flow cytometry data indicate that the main mode of cell death is through apoptosis with some necrotic responses.

Wholly aromatic, thermotropic copolyesters, derived from either 3-phenyl-4,4‘-biphenol, 3,3‘-diphenyl-4,4‘-biphenol, or 1,1‘-binaphthyl-4,4‘-diol with either terephthalic acid or 2,6-naphthalenedicarboxylic acid and 30 mol % 6-hydroxy-2-naphthoic acid, were prepared by melt polycondensation reactions and characterized for their thermotropic liquid crystalline properties by a wide variety of experimental techniques. The three copolyesters containing phenyl-substituted 4,4‘-biphenols had either lower fusion temperature, Tf, or lower crystal-to-nematic transitions, Tm, than those of an analogous series of copolyesters containing unsubstituted 4,4‘-biphenol. Each of them formed a nematic phase above its Tf/Tm values, which was supported from the X-ray diffraction pattern obtained from each of the oriented fibers. Their nematic phases showed both a marbled texture and a Schlieren texture. In one case, a banded texture was also observed, without being subjected to shear. Although the polarized light microscopy ...

Wholly aromatic, thermotropic copolyesters, derived from either 3-phenyl-4,4‘-biphenol (MPBP) or 3,3‘-diphenyl-4,4‘-biphenol (DPBP) with either terephthalic acid (TA) or 2,6-naphthalenedicarboxylic...

Wholly aromatic, thermotropic homopolyesters, derived from 4,4′-biphenol, substituted biphenols, or 1,1′-binaphthyl-4,4′-diol and 3,4′-benzophenone dicarboxylic acid, and two copolyesters, each of which contained 30 mol % of 6-hydroxy-2-naphthoic acid, were prepared by acidolysis polycondensation reactions and characterized for their liquid crystalline properties. The solubility behavior of these polymers has also been investigated. The two homopolymers of phenyl-substituted biphenols with 3,4′-benzophenone dicarboxylic acid were soluble in many common organic solvents. All of the homopolymers had lower Tm/Tf values than those with terephthalic acid, which was attributed to the incorporation of the asymmetric 3,4′-benzophenone dicarboxylate units in a head-to-head and head-to-tail fashion along the polyester chain. Two copolymers had lower Tm values than those of the respective homopolymers, as expected. They formed nematic phases which persisted up to 400°C, except those of phenyl-substituted biphenols with 3,4′-benzophenone dicarboxylic acid. Each of these two polymers also exhibited an accessible Ti transition, and had a broad range of LC phase. They had glass transition temperatures, Tg, in the range of 139-209°C and high thermal stabilities in the temperature range of 465-511°C. © 1995 John Wiley & Sons, Inc.