Synthesis,Characterization and Properties of Novel Poly(Ester-Amide-Urethane)s

A diacid (TOBA) containing an ester group was synthesized by reaction of terephthaloyl chloride with 4-hydroxybenzoic acid. Reaction of the obtained diacid with thionyl chloride resulted in preparation of the related diacid chloride (TOBC). Nucleophilic substitution reaction of 4-aminophenol and also 5-amino-l-naphthol with the prepared diacid chloride afforded two aromatic diols containing ester and amide groups, respectively. Aromatic and semi-aromatic poly(ester-amide-urethane)s were prepared via addition polymerization of different diisocyanates with novel diols. The prepared polyurethanes showed improved thermal stability.     

Physicochemical Study of Ribavirin Complexes with α-, β- and γ-Cyclodextrins

The aim of this work was to characterise interactions between ribavirin (RBV) and native cyclodextrins (CDs). The extent of complexation in solution has been evaluated by high performance liquid chromatography (HPLC) and nuclear magnetic resonance (NMR). Thermogravimetry (TG), differential scanning calorimetry (DSC) and infrared spectroscopy (FT-IR) were used to characterise the solid state of all the binary systems. Complexation of RBV with α-, β-, and γ-CDs was proved by FT-IR, HPLC and thermal analysis. The 1:1 stoichiometry for the complexes was obtained by HPLC. The stability constants for RBV with α-, β- and γ-CD were determined to be 1493, 2606, and 1179 M⁻¹, respectively. Consequently β-CD was the most suitable of the three complexing agents since it showed the highest stability constant. RBV appears not included inside the cavity of the CD because H-3 and H-5 protons were not shifted in the presence of the molecule as proved by NMR. The 2D ROESY spectra did not show any dipolar proton interaction of the RBV with the CDs. Thus the complexation does not seem to be a host–guest inclusion complex but an external intermolecular complex. FT-IR spectral changes due to the RBV carboxamide group vibrations with the CDs confirm this association.     

Novel thermally stable poly(sulfone ether ester imide)s

A novel sulfone ether ester diamine was prepared by a three-step method. Reaction of 1,5-dihydroxy naphthalene with 4-nitrobenzoyl chloride afforded 5-hydroxy-1-naphthyl-4-nitrobenzoate. Reduction of nitro group by iron powder and HCl resulted in preparation of 5-hydroxyl-1-naphthyl-4-aminobenzoate. Reaction of this compound (two moles) with bis (4-chlorophenyl) sulfone led to preparation of a novel sulfone ether ester diamine. Three novel aromatic poly(sulfone ether ester imide)s were synthesized by polycondensation reactions of the prepared diamine with aromatic dianhydrides. Conventional methods were used to characterize the structure of the monomer and polymers. Physical properties of the polymers were also studied. The polyimides showed high thermal stability.     

On Complex Formation between 5-Fluorouracil and β-Cyclodextrin in Solution and in the Solid State: IR Markers and Detection of Short-Lived Complexes by Diffusion NMR

In this work, the nuclear magnetic resonance (NMR) and IR spectroscopic markers of the complexation between 5-fluorouracil (5-FU) and β-cyclodextrin (β-CD) in solid state and in aqueous solution are investigated. In the attenuated total reflectance(ATR) spectra of 5-FU/β-CD products obtained by physical mixing, kneading and co-precipitation, we have identified the two most promising marker bands that could be used to detect complex formations: the C=O and C-F stretching bands of 5-FU that experience a blue shift by ca. 8 and 2 cm⁻¹ upon complexation. The aqueous solutions were studied by NMR spectroscopy. As routine NMR spectra did not show any signs of complexation, we have analyzed the diffusion attenuation of spin–echo signals and the dependence of the population factor of slowly diffusing components on the diffusion time (diffusion NMR of pulsed-field gradient (PFG) NMR). The analysis has revealed that, at each moment, ~60% of 5-FU molecules form a complex with β-CD and its lifetime is ca. 13.5 ms. It is likely to be an inclusion complex, judging from the independence of the diffusion coefficient of β-CD on complexation. The obtained results could be important for future attempts of finding better methods of targeted anticancer drug delivery.     

Noncovalent complexes of water-soluble polymers and organoplatinum compounds as potential time-release antitumor agents

The complexation of appropriate organoplatinum compounds by water-soluble polymers has the potential to provide a time-release formulation which might afford a substantial reduction in the severity of side effects associated with use of organoplatinum antitumor agents. Both poly-(N-vinylpyrrolidone)(PVP) and poly(N-vinyl-5-methyl-2-oxazolidone)(PVOM) form stable, biologically active, molecular complexes with organoplatinum compounds containing polar aromatic ligands. Platinum compounds suitable for complexation by these polymers include cis-dichloro(4-substituted o-phenylenediamine)platinum(II), 4-substitutedcatecholato(1,2-diaminocyclohexane)platinum(II), and 4-substitutedphthallato(1,2-diaminocyclohexane)-platinum(II) compounds.     

Fluorinated polyamides and poly(amide imide)s based on 1,4‐bis(4‐amino‐2‐trifluromethylphenoxy)benzene,aromatic dicarboxylic acids,and various monotrimellitimides and bistrimellitimides: Syntheses and properties

A CF₃‐containing diamine, 1,4‐bis(4‐amino‐2‐trifluromethylphenoxy) benzene ( I ), was prepared from hydroquinone and 2‐chloro‐5‐nitrobenzotrifluoride. Imide‐containing diacids ( V _a–h and VI _a,b ) were prepared through the condensation reaction of amino acids, aromatic diamines, and trimellitic anhydride. Then, a series of soluble fluorinated polyamides ( VII _a–h ) and poly(amide imide)s ( VIII _a–h and X _a,b ) were synthesized from I with various aromatic diacids ( II _a–h ) and imide‐containing diacids ( V _a–h and VI _a,b ) via direct polycondensation with triphenyl phosphate and pyridine. The polyamides and poly(amide imide)s had inherent viscosities of 1.00–1.70 and 0.79–1.34 dL/g, respectively. All the synthesized polymers showed excellent solubility in amide‐type solvents such as N‐methyl‐2‐pyrrolidinone, N,N‐dimethylacetamide, and N‐dimethylformamide and afforded transparent and tough films via solvent casting. Polymer films of VII _a–h , VIII _a–h , and X _a,b had tensile strengths of 91–113 MPa, elongations to break of 8–40%, and initial moduli of 2.1–2.8 GPa. The glass‐transition temperatures of the polyamides and poly(amide imide)s were 254–276 and 255–292 °C, respectively, and the imide‐containing poly(amide imide)s had better thermal stability than the polyamides. The polyamides showed higher transparency and were much lighter in color than the poly(amide imide)s, and their cutoff wave numbers were below 400 nm. In comparison with isomeric IX _{c – h} , poly(amide imide)s VIII _c–h exhibited less coloring and showed lower yellowness indices. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3116–3129, 2004     

Synthesis of poly (ether-sulfone-amide)s by palladium-catalyzed polycondensation of aromatic dibromides containing ether sulfone structure,aromatic diamines,and carbon monoxide

A general method for the preparation of aromatic poly (ether-sulfone-amide)s has been developed. Polymerization is based on the palladium-catalyzed polycondensation of aromatic dibromides containing ether sulfone structural units, aromatic diamines, and carbon monoxide. Reactions were carried out in N, N-dimethylacetamide (DMAc) in the presence of palladium catalyst, triphenylphosphine, and 1,8-diazabicyclo [5,4,0]–7–undecene (DBU), and gave a series of poly (ether-sulfone-amide)s with inherent viscosities up to 0.86 dL/g under mild conditions. The polymers were quite soluble in strong acids, dipolar aprotic solvents, and pyridine. Thermogravimetry of the polymers showed excellent thermal stability, indicating that 10% weight losses of the polymers were observed in the range above 470°C in air. The glass transition temperatures of the polymers were around 230°C, which are higher than those of poly (ether-sulfone) analogues. These polymers also showed the good tensile strengths and tensile modulus. © 1994 John Wiley & Sons, Inc.     

Novel ferrocene modified poly(amide ether amide)s and investigation of physical and thermal properties

A new diamine containing ferrocene group with preformed ether and amide units was prepared via reaction of 1,1′-ferrocenedicarbonyl chloride with two moles of 2,6-bis(5-amino-1-naphthoxy)pyridine. Polycondensation reactions of the prepared diamine with different aromatic and aliphatic diacid chlorides in the presence of trimethylchlorosilane (TMSCl) resulted in preparation of novel ferrocene modified poly(amide ether amide)s. The monomer and polyamides were characterized and the effect of trimethylchlorosilane (TMSCl) as activating agent on the polymerization reaction was studied. The physical and thermal properties of the polyamides including inherent viscosity, solubility, thermal stability and behavior, flame-retardancy and crystallinity of the polymers were studied. The polymers showed good thermal stability and flame-retardancy, and also improved solubility in polar aprotic solvents.     

Novel thermally stable poly(amine hydrazide)s and poly(amine‐1,3,4‐oxadiazole)s for luminescent and electrochromic materials

We describe the preparation, characterization, and luminescence of four novel electrochromic aromatic poly(amine hydrazide)s containing main‐chain triphenylamine units with or without a para‐substituted N,N‐diphenylamino group on the pendent phenyl ring. These polymers were prepared from either 4,4′‐dicarboxy‐4″‐N,N‐diphenylaminotriphenylamine or 4,4′‐dicarboxytriphenylamine and the respective aromatic dihydrazide monomers via a direct phosphorylation polycondensation reaction. All the poly(amine hydrazide)s were amorphous and readily soluble in many common organic solvents and could be solution‐cast into transparent and flexible films with good mechanical properties. These poly(amine hydrazide)s exhibited strong ultraviolet–visible absorption bands at 346–348 nm in N‐methyl‐2‐pyrrolidone (NMP) solutions. Their photoluminescence spectra in NMP solutions or as cast films showed maximum bands around 508–544 and 448–487 nm in the green and blue region for the two series of polymers. The hole‐transporting and electrochromic properties were examined by electrochemical and spectroelectrochemical methods. All obtained poly(amine hydrazide)s and poly(amine‐1,3,4‐oxadiazole)s exhibited two reversible oxidation redox couples at 0.8 and 1.24 V vs. Ag/AgCl in acetonitrile solution and revealed excellent stability of electrochromic characteristics, changing color from original pale yellow to green and then to blue at electrode potentials of 0.87 and 1.24 V, respectively. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3245–3256, 2005     

Thermal stability of aromatic polyesters prepared from diphenolic acid and its esters

The thermal performance of aromatic polyesters (poly(DPA-IPC), poly(MDP-IPC) and poly(EDP-IPC)) prepared from isophthaloyl chloride (IPC) with diphenolic acid (DPA) and its esters were studied with DSC and TG, and the decomposition mechanism of poly(DPA-IPC) were investigated using FTIR and integrated TG/FTIR analyses. As compared with ordinary aromatic polyesters, poly(DPA-IPC) has lower glass transition temperature (159 °C) and much lower thermal stability. It starts to decompose at about 210 °C and is characterized by two-stage thermal decomposition behavior, with active energies of decomposition of 206 kJ/mol and 389 kJ/mol, respectively. The analyses of the decomposition process and products indicate that the pendent carboxyl groups in poly(DPA-IPC) are responsible for its low thermal stability. Accordingly, a decomposition mechanism for the first stage is proposed. With this knowledge in mind, we capped the carboxyl groups in DPA with methyl and ethyl groups to prepare poly(MDP-IPC) and poly(EDP-IPC) from methyl diphenolate and ethyl dipenolate. As expected, these two polymers exhibit obviously improved thermal stability, with onset decomposition temperature of about 300 °C.     

Synthesis,characterization, and thermal properties of novel arylene sulfone ether polyimides and polyamides

A new aromatic sulfone ether diamine was synthesized by nucleophilic aromatic substitution reaction of 5‐amino‐1‐naphthol with bis(4‐chlorophenyl) sulfone in the presence of potassium carbonate in a polar aprotic solvent. Polycondensation reactions of the obtained diamine with pyromellitic dianhydride (PMDA), benzophenonetetracarboxylic dianhydride (BTDA), and hexafluoroisopropylidene diphthalic anhydride (6FDA) resulted in preparation of thermally stable poly(sulfone ether imide)s. Poly(sulfone ether amide)s also were prepared by reaction of the diamine with terephthaloyl chloride (TPC) and isophthaloyl chloride (IPC). The prepared monomer and polymers were characterized by conventional methods. Physical and mechanical properties of polymers, including thermal stability, thermal behavior, solution viscosity, solubility behavior, and modulus, also were studied. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1487–1492, 2000     

Synthesis of aromatic diamine-based benzoxazines and effect of their backbone structure on thermal and flammability properties of polymers

Three kinds of novel aromatic diamine-based benzoxazines containing naphthalene, propane-2,2-diyldibenzene and neopentyl groups in the backbone, respectively (designated as BAPNCP, BAPBACP and BAPNPGCP, respectively), were synthesized and characterized. In addition, the effects of backbone structures on curing behaviors of the monomers and thermal and flammability properties of the resulting polymers were systematically studied. The results indicated that BAPNPGCP displayed the highest enthalpy of the curing reaction associated with the ring-opening of benzoxazine, which was due to the effect of benzoxazine ring content per unit mass. Interestingly, the 5 wt% weight loss temperature and char residue after thermogravimetric test for poly(BAPNPGCP) were 8 °C and 7% higher than those of poly(BAPBACP). Meanwhile, the total heat release of poly(BAPNPGCP) was less than half of that for poly(BAPBACP), indicating the substantial effect of benzoxazine ring content on flammability and char formation. Furthermore, it was found that poly(BAPNCP) gave the best thermal stability and flame retardancy, which was due to the synergistic effect between naphthalene group and benzoxazine ring content. This study provides new insight into the curing behavior of benzoxazine and further understanding on the high performance of polybenzoxazine.     

Hollow nanoparticles via stepwise complexation and selective decomplexation of poly(ethylene imine)

The preparation of hollow nanoparticles with amino groups on the inner side via the stepwise complexation and selective decomplexation of poly(ethylene imine) is presented.     

Topologically unique side-chain polyrotaxanes based on triacetyl-β-cyclodextrin and a poly(ether sulfone) main chain

The synthesis and NMR-spectroscopical characterization of the topological arrangements of new side-chain polyrotaxanes (3a) bearing about 80% of peracetylated cyclodextrins in the side-chains of a functionalized poly(ether sulfone) is described. The characterizations have been conducted in relation to a similar model compound bearing no cyclodextrins (3b) . The results strongly indicate that the cyclodextrins are uniformly located on the side chains, with the bigger opening over the aromatic anilide components of the barrier group. The glass transition temperature (T_g) of the polyrotaxane 3a is in the region of 143°C, which is significantly higher than that of the model polymer 3b having a value of 111°C.     

Fluorescence and viscometry study of complexation of poly(acrylic acid) with poly(acrylamide) and hydrolysed poly(acrylamide)

Interpolymer complexation of poly(acrylic acid) with poly(acrylamide) and hydrolysed poly(acrylamide) was studied by fluorescence spectroscopy and viscometry in dilute aqueous solutions. Changes in chain conformation and flexibility due to the interpolymer association are reflected in the intramolecular excimer fluorescence of pyrene groups covalently attached to the polymer chain. Both poly(acrylamide) and hydrolysed poly(acrylamide) form stable complexes with poly(acrylic acid) at low pH. The molecular weight of poly(acrylic acid) and solution properties such as pH and ionic strength were found to influence the stability and the structure of the complexes. In addition, the polymer solutions mixing time showed an effect on the mean stoichiometry of the complex. The intrinsic viscosity of the solutions of mixed polymers at low pH suggested a compact polymer structure for the complex.     

Rational Design,Synthesis, and Evaluation of Tetrahydroxamic Acid Chelators for Stable Complexation of Zirconium(IV)

Metals of interest for biomedical applications often need to be complexed and associated in a stable manner with a targeting agent before use. Whereas the fundamentals of most transition‐metal complexation processes have been thoroughly studied, the complexation of Zr^IV has been somewhat neglected. This metal has received growing attention in recent years, especially in nuclear medicine, with the use of ⁸⁹Zr, which a β⁺‐emitter with near ideal characteristics for cancer imaging. However, the best chelating agent known for this radionuclide is the trishydroxamate desferrioxamine B (DFB), the Zr^IV complex of which exhibits suboptimal stability, resulting in the progressive release of ⁸⁹Zr in vivo. Based on a recent report demonstrating the higher thermodynamic stability of the tetrahydroxamate complexes of Zr^IV compared with the trishydroxamate complexes analogues to DFB, we designed a series of tetrahydroxamic acids of varying geometries for improved complexation of this metal. Three macrocycles differing in their cavity size (28 to 36‐membered rings) were synthesized by using a ring‐closing metathesis strategy, as well as their acyclic analogues. A solution study with ⁸⁹Zr showed the complexation to be more effective with increasing cavity size. Evaluation of the kinetic inertness of these new complexes in ethylenediaminetetraacetic acid (EDTA) solution showed significantly improved stabilities of the larger chelates compared with ⁸⁹Zr‐DFB, whereas the smaller complexes suffered from insufficient stabilities. These results were rationalized by a quantum chemical study. The lower stability of the smaller chelates was attributed to ring strain, whereas the better stability of the larger cyclic complexes was explained by the macrocyclic effect and by the structural rigidity. Overall, these new chelating agents open new perspectives for the safe and efficient use of ⁸⁹Zr in nuclear imaging, with the best chelators providing dramatically improved stabilities compared with the reference DFB.     

New accelerated strategy for the synthesis of poly(ether ketone) dendrons

A new AB(4)-type hypermonomer with four activated aromatic fluorines was prepared and converted to hyperbranched poly(ether ketones) by nucleophilic aromatic substitution of these fluorine atoms with phenolates. The preparation and application of the AB(4) hypermonomer for the accelerated synthesis of a family of poly(ether ketone) dendrons G2-G4 in good yield are described.     

Studies on Molecular Recongnition of (a)-Cyclodextrin with Diphenyl compounds

The cyclodextrins(CDs) are a class of cyclic oligosaccharides made up of six(a), seven(a)or more [a-(1,4)-linked] D-glucopyranose units, and shaped like truncated cones with primary and secondary hydroxyl groups crowning the narrower rim and wider rim respectively. As they have a hydrophobic cavity of appropriate dimension, they can bind with various guest moleculars, such as hydrocarbon, cyclohexane, aromatic compounds, to form inclusion complexes. The cyclodextins inclusion complexation has been considered an ideal model mimicking the enzyme-substrate interaction and a lot of effect has been devoted to it. In this paper, we report our investigation on the inclusion complexation behavior of a-cyclodextrin(a-CD) with diphenyl compounds in order to further explore the molecular recongnition mechanism of 2:1 inclusion complexation of a-CD with aromatic compounds.Figure 1: Possible structures of the inclusion compounds.The inclusion complexation behavior of a-CD with sym-diphenyl-urea, sym-diphenyl-thiourea and diphenyl kotone as respective guest moleclars was studied by ultraviolet spectrometric titrations.The absorption spectral changes observed for the compounds in the absence and presence of a-CD are used to draw the corresponding Benesi-Hildebrand plots and caculate the complex stability constant value (Ks) for the inclusion compounds.The 2:1 inclusion complexations show higher binding constants by cooperative binding of one guest molecular in the closely two hydrophobic cyclodextrin cavites as compared with 1:1 inclusion complexations.The highest value observed for sym-diphenyl-urea could be due to the formation of a hydrogen bond between the carbonyl group and the hydrogen in the hydroxyl group of CD and this is not possible with sym-tiphenyl-thiourea. The lowest value observed for diphenyl kotone indicate the hydrophobic interaction is one of the binding force of cyclodextrin inclusion complex.     

Synthesis and characterization of heat resistant, pyridine-based polyimides with preformed ether and ester groups

A pyridine-based diamine as a building block for the preparation of heat resistant polyimides was prepared. Reaction of 1,5-dihydroxy naphthalene with 4-nitrobenzoyl chloride resulted in preparation of 5-hydroxy-1-naphthyl-4-nitrobenzoate (HNNB). 5-Hydroxyl-1-naphthyl-4-aminobenzoate (HNAB) was prepared via reduction of nitro group of HNNB. The diamine with built-in ether and ester groups was synthesized by nucleophilic substitution reaction of HNAB with 2,6-dichloropyridine in the presence of K₂CO₃. The obtained diamine was fully characterized and its polycondensation reaction with different aromatic dianhydrides led to preparation of novel heat resistant poly (ether ester imide)s. All the polymers were characterized and their physical and thermal properties were studied.     

Synthesis and photoluminescent and electrochromic properties of aromatic poly(amine amide)s bearing pendent N‐carbazolylphenyl moieties

A series of novel poly(amine amide)s ( IIa – IIl ) with pendent N‐carbazolylphenyl units having inherent viscosities of 0.25–1.06 dL/g were prepared via direct phosphorylation polycondensation from various dicarboxylic acids and a carbazole‐based aromatic diamine. Except for poly(amine amide) IIc , derived from trans‐1,4‐cyclohexanedicarboxylic acid, all the other amorphous poly(amine amide)s were readily soluble in many polar solvents, such as N,N‐dimethylacetamide and N‐methyl‐2‐pyrrolidone (NMP), and could be cast into transparent and flexible films. The aromatic poly (amine amide)s had useful levels of thermal stability associated with relatively high glass‐transition temperatures (268–331 °C), 10% weight loss temperatures in excess of 540 °C, and char yields at 800 °C in nitrogen higher than 60%. These polymers exhibited maximum ultraviolet–visible absorption at 293–361 nm in NMP solutions. Their photoluminescence in NMP solutions exhibited fluorescence emission maxima around 362 and 448–499 nm for aromatic–aliphatic poly(amine amide)s IIa – IIc and aromatic poly (amine amide)s IId – IIl , respectively. The fluorescence quantum yield in NMP solutions ranged from 0.34% for IIj to 4.44% for IIa . The hole‐transporting and electrochromic properties were examined with electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the poly(amine amide) films cast onto an indium tin oxide coated glass substrate exhibited reversible oxidation at 0.81 V and irreversible oxidation redox couples at 1.20 V versus Ag/AgCl in acetonitrile solutions, and they revealed excellent stability of the electrochromic characteristics, with a color change from yellow to green at applied potentials ranging from 0.00 to 1.05 V. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4108–4121, 2006