Chloroform as solvent for the complex formation of alkaline salts with crown ethers and cryptands

The complex formation between different crown ethers and the cryptand (2 2 2) with the ammonium and alkali ions was studied in chloroform as solvent using calorimetric titrations. From the reaction enthalpies for the complex formation with 18-crown-6 and the cryptand (2 2 2) as well as from competitive reactions between both ligands no influence of ion pairs can be detected within the experimental error. Stability constants of the complexes formed could only be obtained in case of the complex formation of Na⁺ with benzo-18-crown-6 and of Cs⁺ with most of the ligands.     

以苯硫脲基乙酸为端基的开链冠醚的合成及其性质研究

由ＮＨ４ＣＮＳ、ＣｌＣＨ２ＣＯＯＨ和开链冠醚桥联二芳胺在无水ＥｔＯＨ中回流，合成了３个以苯硫脲基乙酸为端基的开链冠醚，并经ＩＲ、＾１ＨＮＭＲ，ＭＳ确证了其结构，。初步试验了其与金属离子 的络合性能。     

Benzo[k,l], xanthene–3, 4–dicarboximides and benzimidazoxanthenoisoquinolinones – yellow and orange dyes for synthetic–polymer fibres

Condensation of 4–chloro–l, 8–naphthalic anhydride with 2–nitrophenol afforded 4–(2–nitrophenoxy)–l, 8–naphthalic anhydride, which on reduction followed by Pschorr intramolecular cyclisation gave benzo[k, l]xanthene–3, 4–dicarboxylic acid anhydride. The identity of the product was confirmed by its alternative synthesis from 5–amino–4–phenoxy–l, 8–naphthalic anhydride. Benzo[k, l]xanthene–3, 4–dicarbox–ylic acid anhydride condensed with alkylamines or arylamines and with o–phenylenediamines to yield the corresponding imides and imidazole derivatives, which coloured polyester in fluorescent greenish–yellow to orange hues, respectively, of good fastness to light and sublimation. The colour of the dyes is discussed with respect to analogous ring–closed sulphur– containing heterocycles.     

Preparation and characterization of new photoactive polyamides containing 4‐(4‐dimethylaminophenyl)urazole units

4‐(4‐dimethylaminophenyl)‐1,2,4‐triazolidine‐3,5‐dione ( DAPTD ) was prepared from 4‐dimethylaminobenzoic acid in five steps. The compound DAPTD was reacted with excess acetyl chloride in N,N‐dimethylacetamide (DMAc) solution and gave 1,2‐bisacetyl‐4‐[4‐(dimethylaminophenyl)]‐1,2,4‐triazolidine‐3,5‐dione as a model compound. Solution polycondensation reactions of monomer with succinyl chloride (SucC), suberoyl chloride (SubC), and sebacoyl chloride (SebC) were performed under conventional solution polymerization techniques in the presence of triethylamine and pyridine as a catalyst in N‐methylpyrrolidone (NMP) and led to the formation of novel aliphatic polyamides. These novel polyamides have inherent viscosities in the range of 0.09–0.21 dL/g in N,N‐dimethylformamide (DMF) at 25°C. Fluorimetric studies of the model compound as well as polymers were performed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 947–954, 2007     

Phenol‐containing phthalonitrile polymers – synthesis,cure characteristics and laminate properties

Novolac–phthalonitrile polymers bearing a controlled concentration of phthalonitrile groups were synthesized by condensation of novolac with 4‐nitrophthalonitrile. The cure characteristics monitored by DSC and rheometry indicated acceleration of the cure reaction by the phenolic groups. Fourier transform infrared analysis of the cured products indicated that the cure mechanism was dependent on the extent of phthalonitrile substitution. In phenol‐rich systems, evidence was obtained for the phenol‐mediated reaction of nitrile groups resulting in the formation of isoindoline groups. The phthalonitrile‐rich system underwent crosslinking through formation of triazine and phthalocyanine groups. The phenol groups in the phthalonitrile backbone were conducive to building a stronger interphase in their carbon composites, resulting in better mechanical properties. This was corroborated by morphological studies by SEM. However, these groups were detrimental to the thermal stability of the cured resins. The polymers exhibited very high flame retardancy which improved further on increasing the degree of phthalonitrilation. Copyright © 2012 Society of Chemical Industry     

Novel polyion complex films from chitosan and quarternized poly(4‐vinyl‐N‐carboxymethylpyridine) containing zwitterion structure units

Novel polyion complexes films of chitosan and quarternized poly(4‐vinyl‐N‐carboxymethylpyridine) containing zwitterion structure units were prepared by casting method. The aim of this work was to produce a hydrophilic film with the potential use as a hydrophilic membranes of the types used in membranes distillation and osmotic distillation for separating azeotropic, close‐boiling, and aqueous organic mixtures. Their structure and properties were studied by infrared, wide‐angle X‐ray diffraction, scanning electron microscopy, thermogravimetric analysis, tensile tester, and swelling measurements. The results indicated that polyion complexes occurred between chitosan and quarternized poly (4‐vinyl‐N‐carboxymethylpyridine) containing zwitterion structure units. The thermostability of these blends decreased with the increase of quarternized poly(4‐vinyl‐N‐carboxymethylpyridine) content. Initially, appreciable improvement in tensile strength and breaking elongation were achieved with increase of quarternized poly(4‐vinyl‐N‐carboxymethyl‐pyridine) content to 30%, the maximum value of 46.65 MPa tensile strength and 25.67% breaking elongation were achieved, respectively. The maximum degree of swelling was achieved when the weight ratio of chitosan versus poly(4‐vinyl‐N‐carboxymethylpyridine) was 50 : 50. Meanwhile, the relationship between their structure and properties was also discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Molecular composite of lignin: Miscibility and complex formation of organosolv lignin and its acetates with synthetic polymers containing vinyl pyrrolidone and/or vinyl acetate units

Binary blends and pseudo-complexes of organosolv lignin (OSL) or its acetate (OSL-Ac) with synthetic polymers including poly(vinyl acetate) (PVAc), poly(N-vinyl pyrrolidone) (PVP), and poly(N-vinyl pyrrolidone-co-vinyl acetate) (P(VP-co-VAc)) were prepared by casting from mixed polymer solutions in N,N-dimethylformamide as good solvent and by spontaneous coprecipitation from solutions in tetrahydrofuran (THF) as comparatively poor solvent. Thermal analysis by differential scanning calorimetry showed that OSL was not miscible with PVAc; however, OSL(-Ac) was miscible with PVP to form homogeneous blends irrespective of the degree of acetylation of OSL. OSL formed homogeneous blends with P(VP-co-VAc) with ≥30 mol % of VP contents. Fourier transform infrared spectra measurements for the miscible blends of OSL/PVP revealed the presence of hydrogen bonding interactions between hydroxyls of OSL and carbonyls of VP units. However, there was no evidence for the development of the hydrogen bonding in miscible blends of fully acetylated OSL with PVP. For complexes via THF solutions, its formation was found to be primarily due to a higher frequency of hydrogen bonding interactions. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

1‐amino‐4,5‐8‐naphthalenetricarboxylic acid‐1,8‐lactam‐4,5‐imide‐containing macrocycles: synthesis,molecular modelling and polymerization

Novel macrocycles containing 1‐amino‐4,5‐8‐naphthalenetricarboxylic acid‐1,8‐lactam‐4,5‐imide and 1,4,5‐8‐naphthalenetetracarboxylic bisimide fragments were synthesized by the high‐temperature pseudo‐high‐dilution acylation of the corresponding diols with isophthaloyl chloride, 4,4′‐ and 2,2′‐dichlorocarbonyl biphenyls with up to 60% yield. An important side‐reaction that impedes cyclization was found to be the reaction of diol OH groups with HCl during the acetylation. The ring strain in synthesized macrocyles and model cycles was estimated using the isodesmic reaction approach at the B3LYP/6–311 + G(d,p)//HF/3–21G level of theory. Lactamimide‐containing macrocycles were found to be more strained than bisimide‐containing macrocycles. The ring‐opening polymerization (ROP) of synthesized macrocycles in the molten state shows that the driving force of this process is the strain release on ring‐opening. The ROP of lactamimide‐containing macrocycles was found to be an efficient way to obtain lactamimide‐containing polymers, which are otherwise difficult to synthesize. Copyright © 2003 Society of Chemical Industry     

2‐Naphthol‐containing β‐cyclodextrin–epichlorohydrin copolymers: synthesis,characterization and fluorescence studies

Fluorescent 2‐naphthol (NOH)‐containing β‐cyclodextrin (β‐CD)–epichlorohydrin (EP) copolymers were synthesized. Polymerization was confirmed through viscosity and FT‐IR spectroscopic measurements. Under certain conditions, the copolymers were water‐soluble (molar ratio of EP/β‐CD <22:1), while under other conditions water‐insoluble gels were formed (EP/β‐CD ≥ 22:1). Increase of the EP content to EP/β‐CD ≤ 39:1 increased the fluorescence intensity of the copolymer and shifted the emission maximum from 422 nm toward 352 nm (measured at pH ≥ 12). Further increases in the EP content resulted in a slight decrease in the fluorescence intensity. The fluorescence properties of our system at EP/β‐CD < 22 were sensitive to pH variation, while at EP/β‐CD ≥ 22 no pH effect was observed. These variations can be explained in terms of the exposure of the fluorophore to solvent in soluble versus insoluble polymers, as well as changes in the mode of association (host–guest complexation, trapping within the polymer network, covalent bonding, etc) of NOH with the polymers. Crystallographic studies on a single crystal grown in the absence of EP, but under basic conditions, suggest that host–guest complexation is not an important mode for NOH incorporation. Copyright © 2005 Society of Chemical Industry     

Studies on the δ‐form complex in the syndiotactic polystyrene–organic molecule system. II. Structural investigation of the δ‐form with p‐ and m‐xylene isomers

Syndiotactic polystyrene (sPS) membranes containing different mole fractions of p‐xylene were prepared by a solution‐casting procedure. Complex formation between sPS and xylene was studied by thermogravimetric analysis and Fourier transform infrared spectroscopy. The stability and desorption behavior of the sPS–guest solvent and phase transitions were studied by differential scanning calorimetry. The formation of the δ‐form complex in the presence of different mole fractions of xylene isomers was analyzed and confirmed. The mole fraction of p‐xylene in the dried membrane was found to be higher than that of the corresponding mole fraction in the isomer solvent solution used for casting. This was attributed to the preferential complexing ability of p‐xylene with sPS. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2882–2887, 2003     

Novel poly(phenylene ethynylene)‐type conjugated polymers containing diketopyrrolopyrrole or triphenylpyrazoline units in the main chain: synthesis,characterization and photophysical properties

BACKGROUND: Polymer‐based light emitting diodes (PLEDs) have received considerable attention as they combine the good mechanical and processing properties of polymers with semiconducting behavior, and can be easily fabricated as flexible devices. To obtain high‐performance PLED materials by balancing the carrier injection of poly(phenylene ethynylene)s (PPEs), polymers containing two aryl‐heterocyclic rings, namely diketopyrrolopyrrole (DPP) or triphenylpyrazoline (TPP), have been synthesized and investigated. RESULTS: PPE‐type polymers containing DPP or TPP units were synthesized using Heck–Sonogashira coupling methodology and characterized by ¹H NMR, Fourier transform infrared and UV‐visible spectroscopies, elemental analysis, gel permeation chromatography, photoluminescence (PL), X‐ray diffraction, thermogravimetic analysis and cyclic voltammetry. The polymers obtained are easily soluble in common solvents and form smooth and uniform films. They are yellow or red emitters as revealed by PL. In addition, they show large Stokes shifts, which is in agreement with their twisted molecular structures determined via quantum chemical calculations. CONCLUSION: PPE‐type polymers containing DPP or TPP units were successfully synthesized by coupling polymerization. They exhibit band gaps of 1.73 and 2.37 eV, respectively, and show potential as PLED materials. In addition, DPP‐containing polymers with a very low band gap could be applied as potential photovoltaic materials. Copyright © 2009 Society of Chemical Industry     

Cyclization of 1,4‐Phenylenediacrylic Acid with Thionyl Chloride and Subsequent Suzuki–Miyaura Reactions Revisited. The Products are Benzo[1,2‐b;5,6‐b′]dithiophenes and not Benzo[1,2‐b;4,5‐b′]dithiophenes

The reaction of 1,4‐phenylenediacrylic acid with thionyl chloride was reinvestigated. In earlier reports [Liebigs Ann. Chem. 1980 , 1172; Heterocycles 1995 , 41, 2691; Adv. Synth. Catal. 2009 , 351, 2683] it was claimed that 3,7‐dichlorobenzo[1,2‐b;4,5‐b′]dithiophenes were formed in these reactions. Herein, we provide unambiguous evidence that the assignment of these structures is wrong and that, in contrast, 3,6‐dichlorobenzo[1,2‐b;5,6‐b′]dithiophenes are formed. As a consequence, the structures of these parent molecules and of numerous aryl‐substituted derivatives prepared by Pd‐catalyzed cross‐coupling reactions have to be revised. As many of these dithiophenes were reported to show interesting optical, thermal and electronic properties, the theoretical explanations for these properties have to be reconsidered in the light of the corrected structures reported herein. Our structural assignments are based on X‐ray crystal structure analyses of the parent molecules and on NMR spectroscopic studies of the first unsymmetrical derivatives. Besides, mechanistic investigations based on quantum chemical calculations have been carried out which support the formation of the 3,6‐dichlorobenzo[1,2‐b;5,6‐b′]dithiophene isomers.     

Preparation and properties of a siloxane‐containing 2‐vinylpyridine–styrene–butadiene copolymer with water glass

A siloxane‐containing 2‐vinylpyridine–styrene–butadiene copolymer (PSBR/WG) was prepared from a 2‐vinylpyridine–styrene–butadiene copolymer (PSBR) latex and water glass. The water glass was added slowly, with stirring, to the PSBR latex. The latex mixture was stirred for 3 h at room temperature, and then, it was coagulated with 1N sulfuric acid producing a sulfate of PSBR with siloxane. The physical properties, such as the filling and stiffening effects of the hybrid polymer, and the vulcanizates were improved. An important advantage of this system is that it is possible to prepare the hybrid polymer simply, and the sodium ions formed in the reaction can also be easily removed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 891–899, 2006     

Flame-retardant modification of ethylene–propylene copolymer with monomers containing bromine and/or phosphorus

Vinyl-type monomers containing bromine and/or phosphorus were synthesized and used as flame retardants for ethylene–propylene–diene terpolymer. The monomers were mixed with the base polymer, Sb₂O₃ as a synergist, radical initiator, and other additives, and polymerized in the matrix of the base polymer. The monomers act as an effective flame retardants when they form thermally stable polymers comparable to the base polymer. The efficiency was dependent on the amount of flame-retardant polymer formed in the finished compound.     

The design and synthesis of a novel 1,8-naphthalimide PAMAM light-harvesting dendron with fluorescence “off-on” switching core

A novel polyamidoamine dendron core, peripherally functionalized with 1,8-naphthalimide fluorophores, was configured as a light harvesting antenna in which the system surface was labelled with blue emitting 4-allyloxy-1,8-naphthalimide “donor” dyes capable of both absorbing light and efficiently (96%) transferring the energy to a single, yellow-green emitting 4-N-methylpiperazinyl-1,8-naphthalimide “acceptor” dye. The 1,8-naphthalimide core was designed on the “fluorophore-spacer-receptor” format and was able to function as a fluorescence photoinduced electron transfer sensor. Two different photoinduced electron transfer effects were observed in the new antenna namely that from the receptor to the core fluorophore and that from the polyamidoamine backbone to the peripheral 1,8-naphthalimides. Althogh the core emission intensity of the system was enhanced > four times by reducing the pH from 10 to 2, the fluorescence enhancement of the system in acidic medium, excited within the periphery (λ_ex = 360 nm), was approximately twice that of the core fluorescence enhancement after direct excitation of the focal 1,8-naphthalimide (λ_ex = 420 nm), because of more efficient energy transfer. The observed “off-on” switching of the core fluorescence over a wid pH scale indicates that the novel light harvesting antenna would be able to act as a highly efficient fluorescent sensor.     

Unusual iron-mediated C–N bond formation and synthesis of the Fe(III) complex of a polypyridine ligand with one carboxamide group

A high-spin iron(III) chloro complex [(PaPPy₃)Fe(Cl)](ClO₄) (1, where =N,N-bis(2-pyridylmethyl)amine-N-propyl-2-pyridine-2-carboxamide) has been synthesized via the “template effect” and structurally characterized. The template reaction leads to the formation of a new carbon–nitrogen bond from coupling of a primary alkyl chloride with a secondary amine.     

Characterization and photoluminescence properties of diglycidyl methacrylic resin doped with the Eu3+–β‐diketonate complex

Triaquatris(acetyl acetonate)europium(III) [Eu(acac)₃] at 1, 5, 10, and 15% was doped in diglycidyl methacrylic (DGMA) resin, and their luminescent properties in the solid state are reported. These systems were characterized with elemental analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy. On the basis of TGA data, the thermal stability of the DGMA/Eu(acac)₃x% system was similar to that of the polymer, except at the highest concentration (15%). The DSC results indicated that the new systems were chemically stable and underwent the cure process before decomposition. The emission spectra of the Eu³⁺/acetyl acetonate complex doped in DGMA, recorded at 298 and 77 K, exhibited the characteristic bands arising from the ⁵D₀→⁷F_J transitions (J = 0–4). The luminescence intensity decreased with an increasing precursor concentration in the doped polymer. The system doped at a low concentration (1% Eu³⁺ complex) presented more luminescence efficiency than those doped at 5, 10, and 15%. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 406–412, 2006