Diphenyl Ether Linkage Research Articles

The curing reaction of benzoxazine with bismaleimide/cyanate ester resin and the properties of the terpolymer

Thermosetting terpolymer composed of benzoxazine (BOZ), cyanate ester (BADCy) and maleimide resin (BMI) was prepared via co-curing reactions. The curing reaction of benzoxazine with bismaleimide/cyanate ester resin and the properties of the terpolymer were studied by differential scanning calorimetry (DSC) and Fourier transform-infrared spectroscopy (FT-IR), and the thermal, mechanical and dielectric properties of the terpolymer were also characterized. The FT-IR was applied to monitor the curing reactions of the reactive blends. Three reactions were observed in the curing reactions: the first is the polymerization of cyanate ester after oxazine ring opening, producing the triazine structure; the second is the coreaction between the triazine structure and benzoxazine, forming alkyl isocyanurate and diphenyl ether linkages, followed by the further reaction of the isocyanurate linkage; and the third is the self-polymerization of maleimide resin and benzoxazine, and coreaction with each other. Compared to the polybenzoxazine, the higher crosslinking density of the terpolymer led to the higher glass transition temperature (Tg), as well as the 5% weight loss temperatures (Td5), indicating the better thermal stability of the terpolymer at service temperature. And the data for the mechanical and dielectric properties also showed that the terpolymer performs better than polybenzoxazine and the copolymer.

A diphenyl ether bridged, high triplet energy host material for blue phosphorescent organic light-emitting diodes

Abstract A carbazole type, thermally stable, high triplet energy host material having a diphenylether linkage, 9,9′-(oxybis([1,1′-biphenyl]-4′,3-diyl))bis(9 H -carbazole), was synthesized and the device performances of blue phosphorescent organic light-emitting diodes were studied. The new host material exhibited a high glass transition temperature of 111 °C and a high triplet energy of 2.73 eV for energy transfer to blue triplet emitter. Blue devices were fabricated using the new host material and a high quantum efficiency of 23.5% was achieved.

Reactivity of hydroxyproline-rich glycoproteins and their potential as biochemical tracers of plant-derived nitrogen

The amino acid hydroxyproline (Hyp) has potential for tracing plant N because Hyp-rich glycoproteins (HRGPs), structural proteins in the cell walls of plants, are its only major biochemical source in soil. The reactivity of Hyp in tissue from three vascular plants (black mangrove leaves, smooth cordgrass and cypress needles) was investigated in a 4yr decomposition study to test its suitability as a tracer of plant N. The reactivity was similar to that of bulk plant N in cordgrass and cypress needles, but Hyp was more resistant to decomposition in mangrove leaves. This was likely due to increased cross liking between peptides in HRGPs from dicotyledons vs. other plants. These cross links involve stable diphenyl ether and biphenyl linkages that may protect the HRGP from degradation. The results suggest that Hyp can provide a quantitative estimate of the contribution of plant residues to the detrital N pool in systems dominated by gymnosperm and monocotyledon inputs. A mixing model using litter input representative of boreal forest vegetation demonstrated the potential of Hyp for tracing plant N in soil.

Photoinduced Electron Transfer in an Amine–Corrole–Perylene Bisimide Assembly: Charge Separation over Terminal Components Favoured by Solvent Polarity

An assembly has been synthesised that consists of four units: a meso-substituted corrole (C3), perylene bisimide (PI), and two electron-rich triphenylamine (DPA) units. PI is connected through a 1,4-phenylene bridge to C3, whereas the two DPA units are linked to C3 through a diphenyl ether linkage, which is used for the first time to connect the various moieties. Various synthetic strategies were elaborated, and the chosen one afforded the final system in six steps in an overall yield of 6 %. The resulting assembly, made of three different units, was named a "triad". Excitation of the corrole (C3) or perylene bisimide (PI) units led to the charge-separated state DPA-C3(+)-PI(-) with a rate k>10(11) s(-1) in benzonitrile and dichloromethane (CH(2) Cl(2) ) or with k of the order of 10(10) s(-1) in toluene. The latter charge-separated state decayed to the ground state with a rate k=1.8×10(9) s(-1) in toluene. In the polar solvents benzonitrile and dichloromethane, recombination to the ground state competes with a charge shift to form the distal charge-separated state, DPA(+)-C3-PI(-), the formation of which occurs with a yield of 50 %. Recombination to the ground state of DPA(+)-C3-PI(-) occurs with a rate k=5×10(7) s(-1) in CH(2)Cl(2) and k=2×10(7) s(-1) in benzonitrile.

Miscibility, Microstructure, and Thermal and Dielectric Properties of Reactive Blends of Dicyanate Ester and Diamine-Based Benzoxazine

This study discusses the miscibility, microstructure, and the thermal and dielectric properties of the reactive blends of dicyanate ester of bisphenol A and diamine-based benzoxazine. DSC and IR were applied to monitor the curing reactions of the reactive blends. Three reactions were observed in the curing reactions: the first is the cyclotrimerization of cyanate ester, producing the triazine structure; the second is the coreaction between the triazine structure and benzoxazine, forming alkyl isocyanurate and diphenyl ether linkages, followed by the further reaction of the isocyanurate linkage; and the third is the ring-opening of benzoxazine. The coreaction decomposes the polycyanurate structures and brings parts of the polycyanurate structures into the polybenzoxazine matrix. Thus, a miscible blend can be achieved in all compositions, as judged by the single composition-dependent Tg in the dynamic mechanical and thermal mechanical analyses. The experimental data also show that the dimensional stability ...

O-Seco-RA-XXIV, a possible precursor of an antitumor peptide RA-XXIV, from Rubia cordifolia L.

O-Seco-RA-XXIV, a new cyclic peptide, cyclo-(d-alanyl-l-glutaminyl-N,O-dimethyl-l-tyrosyl-l-alanyl-N-methyl-l-tyrosyl-N-methyl-l-tyrosyl), was isolated from the roots of Rubia cordifolia L. along with RA-XXIV. Its structure and relative stereochemistry were determined by interpretation of the spectroscopic data and X-ray crystallography, and its absolute stereochemistry by the Marfey's amino acid analysis of its acid hydrolysate. Isolation of the two peptides from the same plant source may indicate that O-seco-RA-XXIV is a possible precursor of RA-XXIV and that the formation of the diphenyl ether linkage in the cycloisodityrosine moiety is to be formed after the formation of the cyclohexapeptide chain in this series of peptides.

A High-Throughput, High-Resolution Strategy for the Study of Site-Selective DNA Binding Agents: Analysis of a “Highly Twisted” Benzimidazole-Diamidine

A general strategy for the rapid structural analysis of DNA binding ligands is described as it was applied to the study of RT29, a benzimidazole-diamidine compound containing a highly twisted diphenyl ether linkage. By combining the existing high-throughput fluorescent intercalator displacement (HT-FID) assay developed by Boger et al. and a high-resolution (HR) host-guest crystallographic technique, a system was produced that was capable of determining detailed structural information pertaining to RT29-DNA interactions within approximately 3 days. Our application of the HT/HR strategy immediately revealed that RT29 has a preference for 4-base pair (bp), A.T-rich sites (AATT) and a similar tolerance and affinity for three A-T-bp sites (such as ATTC) containing a G.C bp. On the basis of these selectivities, oligonucleotides were designed and the host-guest crystallographic method was used to generate diffraction quality crystals. Analysis of the resulting crystal structures revealed that the diphenyl ether moiety of RT29 undergoes conformational changes that allow it to adopt a crescent shape that now complements the minor groove structure. The presence of a G.C bp in the RT29 binding site of ATTC did not overly perturb its interaction with DNA-the compound adjusted to the nucleobases that were available through water-mediated interactions. Our analyses suggest that the HT/HR strategy may be used to expedite the screening of novel minor groove binding compounds leading to a direct, HR structural determination.

Synthesis and characterization of phthalazinone containing poly(arylene ether)s via a novel N–C coupling reaction

AbstractHigh‐molecular‐weight poly(phthalazinone)s with very high glass‐transition temperatures (Tg's) were synthesized via a novel N–C coupling reaction. New bisphthalazinone monomers (7a–e) were synthesized from 2‐(4‐chlorobenzoyl) phthalic acid in two steps. Poly(phthalazinone)s, having inherent viscosities in the range of 0.34–0.91 dL/g, were prepared by the reaction of the bis(phthalazinone) monomers with an activated aryl halide in a dipolar aprotic solvent in the presence of potassium carbonate. The poly(phthalazinone)s exhibited Tg's greater than 230 °C. polymer 8b synthesized from diphenyl biphenol and bis(4‐flurophenyl) sulfone demonstrated the highest Tg of 297 °C. Thermal stabilities of the poly(phthalazinone)s were determined by thermogravimetric analysis. All the poly(phthalazinone)s showed a similar pattern of decomposition with no weight loss below 450 °C in nitrogen. The temperatures of 5% weight loss were observed to be about 500 °C. The poly(phthalazinone)s containing 4,4′‐isopropylidenediphenol and 4,4′‐(hexafluoroisopropylidene) diphenol and diphenyl ether linkage were soluble in chlorinated solvents such as chloroform. Other poly‐(phthalazinone)s were soluble in dipolar aprotic solvents such as N,N′‐dimethylacetamide. The soluble poly(phthalazinone)s can be cast as flexible films from solution. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2481–2490, 2003

A conformational study of aromatic imide compounds. part 1. Compounds containing diphenyl ether and benzophenone moieties

An attempt was made to estimate the dihedral angles φ, ψ, ω 1, and ω 2, of bis(4-hydroxyphthalimide)s (BHPI) and bis(phenylphthalimides)s (BPI) having diphenyl ether or benzophenone linkages at the center of molecules using solid-state 13C CP/MAS NMR and ab initio nuclear shielding calculations. The TOSS and TOSS & DD pulse sequences were performed in the NMR measurements to obtain exact chemical shifts of each carbon. Total energies were calculated using the B3LYP/6-31G(d) level of theory, and shielding constants were calculated using the RHF/6-31G(d) level of theory for diphenyl ether and benzophenone by varying the angles of φ, ψ from 0 to 180° at intervals of 10°. The comparison of nuclear shielding calculations between RHF/6-31G(d) and B3LYP/6-311+G(2d,p) levels of theory indicates that RHF/6-31G(d) has sufficient reliability for calculating shielding constants of diphenyl structures. Since the nuclear shieldings are displaced depending on the dihedral angles, the dihedral angles of BHPIs and BPIs can be estimated by comparing the experimental chemical shifts with the calculated shielding constants. The BHPIs, BPIs and a related polyimide ODPA/ODA were estimated to have symmetric conformations having identical φ and ψ and identical ω 1 and ω 2.

Four dimeric aporphine-containing alkaloids from Thalictrum fauriei.

Four dimeric alkaloids (1-4) containing an aporphine unit and representing unique structural features were obtained from Thalictrum fauriei and were characterized by spectral and chemical methods. Fauripavine (1), with a munitagine pavine unit, is the first such dimer with an aporphine C-1 diphenyl ether connection; although fauridine (2), also the first of its class, has codamine, a benzyl tetrahydroisoquinoline, linked at the same position. Faurithaline (3) and its 3-methoxy analogue 4, both with reticuline, a benzyl tetrahydroisoquinoline as the second unit, are the first dimers with the diphenyl ether linkage at C-8 of an aporphine oxygenated at C-10 and C-11. Oconovine (8) was converted to 8-hydroxy-O-methyloconovine (12) to determine the effect of oxygenation at C-8 on the proton chemical shift of the C-7 hydrogens in a study to support the C-8 ether linkage of alkaloids 3 and 4. All the alkaloids have the S-configuration at their asymmetric centers as established from their CD spectra when compared with those of model compounds.

Chemical constituents from Dehaasia triandra. II. Five new alkaloids, secoxanthoplanine, dehydroisocorydione, 11,8′- O-bisisocorydine, (8,8′- R)- and (8,8′- S)- bisisocorydine, isolated from the leaves

A continuous study on the constituents from the leaves of Dehaasia triandra Merr. resulted in the isolation of five additional novel alkaloids- secoxanthoplanine ( 1), dehydroisocorydione ( 2), (8,8′- R)- ( 3) and (8,8′- S)-bisisocorydine ( 4), and 11,8′- O-bisisocorydine ( 5). Compounds 3 and 4 are the first C-C linked bisaporphines at C-8 while 5 is the first bisaporphine with a diphenyl ether-linkage at C-8 and C-11. Besides elucidation based on a spectral analysis, the structures of 1, 3 and 4 were further confirmed by semisynthesis.

Conformational Studies of Thyroid Hormones. I. The Diphenyl Ether Moiety

Conformational flexibility round the diphenyl ether linkage in the thyroid hormones has been investigated by means of molecular orbital (AM1) and classical potential-energy calculations. The results obtained from these theoretical approaches are in qualitative agreement with those from n.m.r. spectroscopy, i.e., the barrier to rotation around this structural feature is sufficiently low to allow rapid interconversion between two stable conformers to occur at room temperature. Two pathways of rotation around the diphenyl ether bridge were explored and were both calculated to be approximately 14-15 kJ mol-1 by the AM1 method. This compares with the experimental barrier of 36 kJ mol-1. The potential-energy calculations gave barriers up to an order of magnitude larger which were inconsistent with experimental observations. A comparison of the AM1 data with results from previous studies with CNDO/2, which predicted a larger barrier, is also given. The detailed mode of interconversion around the two torsion angles involved in diphenyl ether rotation is investigated, as is the interplay of the bulky iodo substituents with the second aromatic ring during such conformational changes. The nature of torsion angle cooperation during rotations around this linkage is discussed.

Novel polybenzoxazinones with tricyclic fused‐rings

AbstractA series of polybenzoxazinones containing phenoxathiin and phenoxaphosphine units were prepared from tricyclic diacid chlorides and 4,4′‐diaminobiphenyl‐3,3′‐dicarboxylic acid and 4,4′‐diamino‐3,3′‐diphenylmethane dicarboxylic acid. The low temperature solution polymerization technique afforded polyamic acid which subsequently underwent cyclization along the polymer chain in a solvent mixture of refluxing N,N′‐dimethylacetamide, acetic anhydride, and pyridine to give polybenzoxazinones in moderate yields. The polymers thus obtained had inherent viscosities in the range of 0.15–0.23 dL/g, were sparingly soluble in N‐methyl‐2‐pyrrolidone, and were found to be thermally more stable than the corresponding open‐chain polymer with diphenylether linkage.

Photodegradation of the pyrethroid insecticide fenpropathrin in water, on soil and on plant foliage

AbstractThe photodegradation of fenpropathrin [(RS)‐α‐cyano‐3‐phenoxybenzyl 2,2,3,3‐tetramethylcyclopropanecarboxylate] (I), in water, on soil and on plant foliage, was investigated using 14C‐preparations labelled separately at the cyano group, cyclopropyl‐C1 or in the benzyl ring. On exposure to sunlight, I was photodecomposed with initial half‐lives of >6 weeks in distilled water, 6.0 weeks in humic acid aqueous solution, 2.7 weeks in river water, 1.6 weeks in sea water and 0.5 of a day in 2% aqueous acetone. A triplet photosensitiser, acetone, together with naturally occurring substances in river and sea water, including humic acid, enhanced the photodegradation of I. On three kinds of soil, I was rapidly photodegraded with initial half‐lives of 1–5 days, whereas it was fairly photostable on a mandarin orange leaf. The photoreactions involved were: decarboxylation, hydration of the cyano group to carboxamide, cleavage of the ester or the diphenyl ether linkage, hydrolysis of the carboxamide group to carboxyl, and hydroxylation at either or both of the gem dimethyl groups. The predominant reactions in water were decarboxylation, ester bond cleavage and photo‐induced evolution of [14C] carbon dioxide from the [14C] cyano label; on soil, hydration or ester bond cleavage predominated. The hydration was also of importance in river and sea water. Decarboxylation did not occur on soil and plant foliage.

Heat‐resistant polymers with thianthrene analog units. II . Aromatic polyamides

AbstractA series of polyamides which contained thianthrene, phenoxatiin, and dibenzo‐p‐dioxin units was synthesized from tricyclic fused‐ring diamines and aromatic diacid chlorides by solution polycondensations at a low temperature. The amorphous polyisophthalamides were highly soluble in polar organic solvents, whereas some of the polyterephthalamides with a fair degree of crystallinity were insoluble. The solubility of the series of polyamides increased in the order of the dibenzo‐p‐dioxin‐containing polymers < phenoxatiin‐containing polymers < thianthrene‐containing polymers. The thermal stability increased in the reverse order and the dibenzo‐p‐dioxinpolyamides were more thermostable than the corresponding open‐chain polymers with diphenyl ether linkages. The polyamides derived from 2,8‐oriented tricyclic diamines showed somewhat lower glass transition temperatures than those from 2,7‐oriented diamines.

Preparation and properties of polyamides and polyimides containing phenoxathiin units

AbstractNovel polyimides and polyimides having phenoxathiin units have been prepared. Polyamides with inherent viscosities in the range of 0.5–2.9 were readily prepared by the polycondensations of phenoxathiin diamines with aromatic diacyl chlorides and of aromatic diamines with new phenoxathiin diacyl chlorides. The polyimides were synthesized from phenoxathiin diamines and pyromellitic dianhydride by using a two‐step procedure. The polyamic acids which formed in the first step had inherent viscosities ranging from 1.0 to 1.6, and they were converted to the polyimides by thermal cyclodehydration. Some of the phenoxanthiin‐containing polyamides were highly soluble in polar amide solvents and dimethyl sulfoxide. A series of novel polymers containing phenoxathiin units were much more thermostable than the corresponding polymers having open‐chain diphenyl ether linkages.

Interaction Between Thyroid Hormones and Erythrocyte Membranes: Competitive Inhibition of Binding131I-L-Triiodothyronine and131I-L-Thyroxine by Their Analogs

Molecular structural characteristics of thyroid hormones which influence binding to the erythrocyte membranes were investigated by competitive binding experiments. The ability of thyroid hormone analogs to displace 131 I-L-thyroxine and 131 I-L-triiodothyronine from the membranes was considered evidence of their competitive binding. The diphenyl ether linkage (thyronine) was essential as compounds with a single aromatic ring were weakly competitive. The presence of three iodine atoms at 3, 5 and 3' positions on thyronine was optimal for maximal competitive binding. There was weak competitive binding of analogs if chlorine or bromine was substituted for iodine. The alanine side chain was required for optimal binding as N-acetyl-l-thyroxine and various deaminated analogs were poor competitors compared to T4 and T3. L-isomers of T4 and T3 showed greater competitive binding to erythrocyte membranes than the corresponding d-isomers.

AUTOXIDATION OF HALOGENATED METHYL THYROPROPIONATES CATALYZED BY BIS(3-SALICYLIDENEAMINOPROPYL)AMINECOBALT(II). A MODEL REACTION FOR THE METABOLISM OF THYROXINE

Abstract Autoxidation of halogenated methyl thyropropionates catalyzed by bis(3-salicylideneaminopropyl)aminecobalt(II) gave rise to direct cleavage of their diphenyl ether linkage. The reaction provides a model for the enzymic degradation of thyroxine to form diiodotyrosine.

A convenient method for the determination of the attached position of diphenyl ether linkage in bisbenzylisoquinoline alkaloids

A convenient method for the determination of the attached position of diphenyl ether linkage in bisbenzylisoquinoline alkaloids

Model reactions for the metabolism of thyroxine. I. Nonenzymic cleavage of the diphenyl ether linkage of 3'-hydroxythyropropionic acid

Model reactions for the metabolism of thyroxine. I. Nonenzymic cleavage of the diphenyl ether linkage of 3'-hydroxythyropropionic acid