Biphenyl Ether Research Articles

Preparation and characterization of thermally stable poly(piperazine amide)/PPBES composite nanofiltration membrane

Copoly(phthalazinone biphenyl ether sulfone) (PPBES) with excellent performance is utilized to fabricate the substrate membrane of the composite nanofiltration (NF) membrane and the functional layer of the NF membrane is prepared by the interfacial polymerization from piperazine (PIP) and trimesoyl chloride (TMC). The performances of the substrate ultrafiltration (UF) membrane such as molecular weight cut-off (MWCO) and hydrophilicity are also studied to improve the composite membrane performance. When the composite membrane is prepared under optimized conditions and tested at 1.0 MPa and 20 °C, the flux of the composite NF membrane is about 77 L/m 2 h and the Na 2SO 4 rejection of it is about 97.5%. The surface morphologies of the composite membrane and substrate membrane are observed by scanning electron microscopy (SEM). The flux is increased from 61 to 290 L/m 2 h with the rejection of the membrane decreases 3.8% when the operation temperature increases from 18 °C to 85 °C at 1.0 MPa.

Preparation and characterization of a modified montmorillonite/sulfonated polyphenylether sulfone/PTFE composite membrane

Organically modified montmorillonites are valuable materials that have been used to improve the permeability, water retention, and proton conductivity of proton exchange membrane for fuel cells. A sulfonated montmorillonite/sulfonated poly (biphenyl ether sulfone)/Polytetrafluoroethylene (SMMT/SPSU-BP/PTFE) composite membrane was prepared for fuel cells. The thermal stability of the SMMT was tested by the thermogravimetry-mass spectrometry (TGA-MS) and its structure in the composite membrane was characterized by X-ray diffraction (XRD). It was found that SMMT was stable up to 205 °C and the interlayer distance of the nanoclay expanded from 1.43 nm to 1.76 nm after the organic sulfonic modification. The SMMT was completely exfoliated in the composite membranes. The properties of ion-exchange capacity, water uptake, swelling ratio, proton conductivity, and mechanical strength of the composite membranes were investigated as well. The good water retention of SMMT made the SMMT/SPSU-BP and SMMT/SPSU-BP/PTFE composite membranes have about 20% more bound water than the SPSU-BP membrane. Due to the reinforce effect of the PTFE porous film, the SMMT/SPSU-BP/PTFE composite membrane presented low swelling even at elevated temperature and high stress strength. All of the properties indicate that the SMMT/SPSU-BP/PTFE composite membrane is very promising as the PEM for medium temperature PEMFCs.

Triclosan susceptibility and co-metabolism – A comparison for three aerobic pollutant-degrading bacteria

The antimicrobial agent triclosan is an emerging and persistent environmental pollutant. This study evaluated the susceptibility and biodegradation potential of triclosan by three bacterial strains (Sphingomonas wittichii RW1, Burkholderia xenovorans LB400 and Sphingomonas sp. PH-07) that are able to degrade aromatic pollutants (dibenzofuran, biphenyl and diphenyl ether, respectively) with structural similarities to triclosan. These strains showed less susceptibility to triclosan when grown in complex and mineral salts media. Biodegradation experiments revealed that only strain PH-07 was able to catabolize triclosan to intermediates that included hydroxylated compounds (monohydroxy-triclosan, and dihydroxy-triclosan) and the ether bond cleavage products (4-chlorophenol and 2,4-dichlorophenol), indicating that the initial dihydroxylation occurred on both aromatic rings of triclosan. Additional growth inhibition tests demonstrated that the main intermediate, 2,4-dichlorophenol, was less toxic to strain PH-07 than was triclosan. Our results indicate that ether bond cleavage might be the primary mechanism of avoiding triclosan toxicity by this strain.

Giant Thermoelectric Effect from Transmission Supernodes

We predict an enormous order-dependent quantum enhancement of thermoelectric effects in the vicinity of higher-order interferences in the transmission spectrum of a nanoscale junction. Single-molecule junctions based on 3,3'-biphenyl and polyphenyl ether (PPE) are investigated in detail. The nonequilibrium thermodynamic efficiency and power output of a thermoelectric heat engine based on a 1,3-benzene junction are calculated using many-body theory and compared to the predictions of the figure-of-merit ZT.

Vibrational spectroscopic investigation and DFT studies on 2,2′,4,4′-tetrabromodiphenyl ether

In the present work, the infrared (IR) and Raman spectra of 2,2′,4,4′-tetrabromodiphenyl ether have been measured in the ranges of 400–4000 cm −1 and 100–4000 cm −1. The geometry optimized by the density functional theory Becke-3-Lee-Yang-Parr (B3LYP) method with the 6-31G(d) basis set was in good agreement with the experimental data of analogues. The results have shown that the dihedral angle of biphenyl ether significantly increases with the addition of bromine substitution. The vibrational frequencies were evaluated by the B3LYP method in conjunction with basis sets of 6-31G(d), 6-31G(2df,p), 6-311+G(d,p), 6-311G+(2df,p), and 6-311++G(d,p), separately. The scaled frequencies resulted in excellent agreement with the observed spectral patterns. The correlation analysis and statistical comparisons indicated that the basis sets larger than 6-31G(d) resulted in no significant improvement in the accuracy of the vibration frequencies. The detailed assignments were performed according to the calculated results for B3LYP/6-31G(d) and then compared with those from a previous study on 4,4′-dibromodiphenyl ether. The absence of coupling of C–O stretching and adjacent C–H in-plane deformation indicated a strong steric effect owing to the ortho bromine atoms in the title compound. Moreover, the quantum theory of atoms in molecules (QTAIM) and the Moller–Plesset second-order perturbation (MP2) method are applied to exclude the possible formation of intramolecular non-covalent interactions such as Br⋯Br and C–H⋯Br.

Desalination of dye utilizing copoly(phthalazinone biphenyl ether sulfone) ultrafiltration membrane with low molecular weight cut-off

Copoly(phthalazinone biphenyl ether sulfone) (PPBES) ultrafiltration (UF) membrane with low molecular weight cut-off (MWCO) possesses excellent thermal resistance and it is suitable to be utilized in dye wastewater treatment at high temperature. The rejection of polyethylene glycol (PEG1000) of the membrane was 100% while the flux was 232 L/m 2 h at 20 °C and 0.2 MPa. It was showed that the rejections of NaCl and Na 2SO 4 were both 0%. The rejections of Congo Red (Direct Dye), Sulfur Black B (Sulfur Dye) and Gentian Violet (Anionic Dye) were all 100% while the rejections of C. I. Reactive Yellow 86 (Reactive Dye), C. I. Disperse Red 73 (Disperse Dye) and Acid Chrome Blue K (Cationic Dye) were 79%, 54% and 43%, respectively. The fluxes of the membrane during treatment were all higher than 87 L/m 2 h at 20 °C and 0.2 MPa except for C. I. Disperse Red 73. Effect of inorganic salt concentration on membrane performance was investigated. Thermal resistance of the membrane was also evaluated with Sulfur Black B. It was found that the flux increased 4.5 times while the rejection did not decline when the operation temperature was raised from 20 °C to 95 °C. The membrane ran 20 h at 90 °C without the membrane performance decline which showed that the membrane had good thermal resistance.

In Vitro Assay Shows That PCB Metabolites Completely Saturate Thyroid Hormone Transport Capacity in Blood of Wild Polar Bears (Ursus maritimus)

Persistent chemicals accumulate in the arctic environment due to their chemical reactivity and physicochemical properties and polychlorinated biphenyls (PCBs) are the most concentrated pollutant class in polar bears (Ursus maritimus). Metabolism of PCB and polybrominated biphenyl ether (PBDE) flame-retardants alter their toxicological properties and these metabolites are known to interfere with the binding of thyroid hormone (TH) to transthyretin (TTR) in rodents and humans. In polar bear plasma samples no binding of [125I]-T(4) to TTR was observed after incubation and PAGE separation. Incubation of the plasma samples with [14C]-4-OH-CB107, a compound with a higher binding affinity to TTR than the endogenous ligand T(4) resulted in competitive binding as proven by the appearance of a radio labeled TTR peak in the gel. Plasma incubation with T(4) up to 1 mM, a concentration that is not physiologically relevant anymore did not result in any visible competition. These results give evidence that the binding sites on TTR for T(4) in wild living polar bears are completely saturated. Such saturation of binding sites can explain observed lowered levels of THs and could lead to contaminant transport into the developing fetus.

Mechanical and Thermal Properties of Poly(phthalazinone biphenyl ether sulfone)/PEEK Blends

A series of blends with various compositions are prepared by melt extrusion on the basis of novel copoly(phthalazinone biphenyl ether sulfone) (PPBES) and poly(ether ether ketone) (PEEK). The melt flowability, mechanical and thermal properties of the blends are studied. The results show that the incorporated PEEK has a large influence on the melt viscosity and thermal stability of blends. The tensile strength of the blends remains at about 90 MPa at room temperature; PPBES improves the mechanical properties of PEEK at 150°C. The flexural strength and modulus of the PPBES/PEEK blends also increase with the addition of PEEK.

Synthesis and Characterization of Novel Copoly(aryl ether sulfone) Containing Phthalazinone and Biphenyl Moieties

A series of poly(ether sulfone)s copolymers (BP-COPPESs) based on phthalazinone and biphenyl moieties were synthesized by nucleophilic displacement reaction from 4-(4-hydroxyphenyl)-2,3-phthalazin-1-one (DHPZ), biphenol (BP) and bis(4-chlorophenyl) sulfone (BCS). The experimental results indicated that the higher initial concentration of the polymerization reaction resulted in lower cyclics content and narrower molecular weight distribution of resultant copolymers. Moreover, the molecular weight decreased with increasing content of phthalazinone moiety of the main chain. These copolymers showed high glass transition temperatures ( Tg values) together with superior thermal properties. These copolymers were soluble in various aprotic solvents and were amorphous as evidenced by wide-angle X-ray diffraction. The molecular weights of BP-COPPES64 (60% phthalazinone moiety) could be controlled by utilizing excess molar content of BCS monomer. The rheological property test of copolymers indicated that the torque values decreased with increasing biphenyl group and ether linkage content.

Design and synthesis of aryl ether inhibitors of the Bacillus anthracis enoyl-ACP reductase.

The problem of increasing bacterial resistance to the current generation of antibiotics is well documented. Known resistant pathogens such as methicillin-resistant Staphylococcus aureus are becoming more prevalent, while the potential exists for developing drug-resistant pathogens for use as bioweapons, such as Bacillus anthracis. The biphenyl ether antibacterial agent, triclosan, exhibits broad-spectrum activity by targeting the fatty acid biosynthetic pathway through inhibition of enoyl-acyl carrier protein reductase (ENR) and provides a potential scaffold for the development of new, broad-spectrum antibiotics. We used a structure-based approach to develop novel aryl ether analogues of triclosan that target ENR, the product of the fabI gene, from B. anthracis (BaENR). Structure-based design methods were used for the expansion of the compound series including X-ray crystal structure determination, molecular docking, and QSAR methods. Structural modifications were made to both phenyl rings of the 2-phenoxyphenyl core. A number of compounds exhibited improved potency against BaENR and increased efficacy against both the Sterne strain of B. anthracis and the methicillin-resistant strain of S. aureus. X-ray crystal structures of BaENR in complex with triclosan and two other compounds help explain the improved efficacy of the new compounds and suggest future rounds of optimization that might be used to improve their potency.

Discovery of novel series of benzoic acid derivatives containing biphenyl ether moiety as potent and selective human β 3-adrenergic receptor agonists: Part IV

Identification and SAR study of novel series of β 3-AR agonists with benzoic acid are described. Conversion of ether linkage position of phenoxybenzoic acid derivative 2b led to compound 7b with moderate β 3-AR activity. Further modification in right, center and left parts of compound 7b was investigated to improve the β 3-AR potency and selectivity. Compounds 7g and 7k, with the bulky aliphatic-substituted group at 2-position of benzoic acid moiety, were identified as potent and selective β 3-AR agonists. In addition, in vivo efficacy of compounds 7g and 7k was exhibited on dog OAB model.

Discovery of a Novel Series of Benzoic Acid Derivatives as Potent and Selective Human β3 Adrenergic Receptor Agonists with Good Oral Bioavailability. 3. Phenylethanolaminotetraline (PEAT) Skeleton Containing Biphenyl or Biphenyl Ether Moiety

We designed a series of benzoic acid derivatives containing the biphenyl ether or biphenyl template on the RHS and a phenylethanolaminotetraline (PEAT) skeleton, which was prepared by highly stereoselective synthesis, to generate two structurally different lead compounds ( 10c, 10m) with a good balance of potency, selectivity, and pharmacokinetic profile. Further optimization of the two lead compounds to improve potency led to several potential candidates (i.e., 11f, 11l, 11o, 12b). In particular, biphenyl analogue 12b exhibited an excellent balance of high potency (EC50 = 0.38 nM) for beta3, high selectivity over beta1 and beta2, and good pharmacokinetic properties in rats, dogs, and monkeys.

Retipolides – Unusual Spiromacrolactones from the Mushrooms Retiboletus retipes and R. ornatipes

AbstractMushrooms of the genus Retiboletus contain the retipolides A–D (1, 6–8), unusual 14‐membered spiromacrolides with a biphenyl ether linkage. The structures of these metabolites suggested a biogenetic sequence starting from retipolide E (16), which could furnish the unique 2(3H)‐oxepinone unit of retipolide C (7) via an oxidative enlargement of the 4‐hydroxyphenyl ring. A subsequent O/C‐acyl shift would then lead to the cyclopenta[c]pyran system of retipolide A (1). The proposed precursor 16 was synthesized and subsequently detected in the fungal extract in addition to the probable biosynthetic intermediates butyrolactone II (13), tyrosol (14), and secoretipolide E (15). The structural elucidation of retipolide A (1) was accomplished after transformation into a methoxyfulvene derivative 2a, and the absolute (R) configuration of 1 was assigned by a single‐crystal X‐ray analysis of the corresponding (S)‐sec‐butoxyfulvene analogue 2b. Some samples of R. retipes/ornatipes contained isoretipolide A (9), an isomer of 1 with a highly strained 12‐membered lactone ring incorporating two C,C‐coupled 4‐hydroxyphenyl units. A comparison of the CD spectrum of retipolide A (1) with those of the other retipolides and isoretipolide A (9) indicates that all of these macrolides possess R configuration. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Rapid screening for bisbibenzyls in bryophyte crude extracts using liquid chromatography/tandem mass spectrometry

A simple and rapid qualitative liquid chromatography-diode-array detection/tandem mass spectrometry (LC-DAD/MS/MS) method was developed and validated for screening bisbibenzyl compounds in bryophyte crude extracts at sub-ppm levels. After simple extraction with ethanol and analyte concentration with diethyl ether, the extracts were subjected to LC-DAD/MS/MS analysis. The overall instrument turnaround time was 50 min to obtain baseline separation of bisbibenzyl isomers in bryophytes. MS full scan, MS/MS precursor ion scan and MS/MS product ion scan modes were used for the screening. The bisbibenzyl standards studied gave limits of detection (LODs) at or below 10 ng/mL. The results also indicated that the method had acceptable precision to be used on a day-to-day basis for qualitative identification. The bisbibenzyl types, i.e. one biphenyl ether bond (A-type), two biphenyl ether bonds (B-type), one biphenyl ether and one biphenyl bond (C-type), or other biphenyl types can be differentiated by their ESI-MS/MS product profiles, and the number of alkoxyl substituents can also be identified. The linkage sites of biphenyl and biphenyl ether bonds cannot be identified for an unknown bisbibenzyl solely from its mass spectra. This system was used to support three screening assays of bryophytes including Marchantia polymorpha L., Ptagiochasm intermedium L. and Asterella angusta, which were collected from different places in China. From them, 7/12, 8/5 and 8/9 confirmed/unconfirmed bisbibenzyls were identified, respectively, based on their MS/MS data, UV spectra and the retention behavior. The screening method considerably reduced the time and the cost for the qualitative analyses, and the structure-fragmentation-UV relationships will facilitate the high-throughput screening (HTS) of bisbibenzyl compounds in bryophytes. It is also intended as a simple and convenient way for the determination of other structural families of natural products.

Investigation of the Ag-SiO 2/sulfonated poly(biphenyl ether sulfone) composite membranes for fuel cell

The Ag-SiO 2/SPSU-BP composite membrane has been fabricated aiming to reduce the degradation of membrane by hydrogen peroxide attacking. The composite membrane was characterized by SEM and XRD analysis. Water uptake study and thermo-gravimetric analysis indicated that the hydrophilic Ag/SiO 2 particles retain more water in the composite membrane. The hydrogen peroxide decomposition tests showed that the Ag/SiO 2 in the composite membranes had a catalyst activity for the decomposition of peroxide. The accelerated fuel cell life tests were performed via the open-circuit voltage (OCV) tests. The durability of PEMFC with the Ag-SiO 2/SPSU-BP composite membrane was improved. The result of hydrogen crossover study means that the addition of the Ag/SiO 2 catalyst reduced the degradation of membrane by peroxide attack.

Study of bis(bibenzyls) in bryophytes using electron ionization time‐of‐flight and electrospray ionization triple‐quadrupole mass spectrometry

A detailed analysis of mass spectra generated from bis(bibenzyl) compounds in bryophytes under electron ionization time-of-flight (EI-TOF) and electrospray ionization triple-quadrupole (ESI-TQ) mass spectrometry conditions is reported. Proposed structures of the fragment ions were obtained by tracking the functional groups of 15 bis(bibenzyls), the structures of which are similar except for some alkoxyl substituents and linkage sites of biphenyl ether bonds. The elucidation was aided by the use of accurate mass measurements. Attempts have been made to provide rational pathways for the formation of these fragment ions, and a generalized fragmentation mechanism is proposed. The bis(bibenzyls) mentioned in this study include three types according to their structure characteristics, i.e. one biphenyl ether bond (A-type), two biphenyl ether bonds (B-type), one biphenyl ether and one biphenyl bond (C-type). The three types display different EI-MS and ESI-MS/MS product profiles, by which the bis(bibenzyl) type and the number of alkoxyl substituents can be identified. Isomers of bis(bibenzyls) can be differentiated to some extent, while the linkage sites of biphenyl ether bonds are difficult to identify. The structure-fragmentation relationships will facilitate the characterization of other bis(bibenzyls) and this will be of value for the high-throughput screening of novel bis(bibenzyls) in bryophytes.

Novel random copoly(arylene ether-thioether ketone)s based on 2,2-bis(4-mercaptophenyl)propane and 4,4′-dihydroxybiphenyl: Synthesis and properties

A series of novel poly(arylene ether-thioether ketone) random copolymers were synthesised by copolymerisation of 4,4′-difluorobenzophenone with bis( N, N-dimethyl- S-carbamate) of 2,2-bis(4-mercaptophenyl)propane (MBTA) and 4,4′-dihydroxybiphenyl (BP). The syntheses were performed using a one pot polymerisation method starting from different mole percentages of BP with respect to MBTA, varying from 20% to 80%. The copolymers were obtained in good yields and had molecular weights in the range 10,000–17,000 as determined by GPC. The structural proof was provided by 1H-NMR spectroscopy. In order to study the effect of the copolymerisation on the thermal properties and crystal behaviour, also the poly(ether biphenyl ether ketone) homopolymer (PEBEK) has been synthesised using the same polymerisation method. The TGA analysis shows that the high stability of PEBEK is only slightly affected by the introduction of co-units in the chain. The copolymers with an amount of PEBEK variable from 80 to 50 mol% are crystalline, with percentage of crystallinity and melting temperature which decrease as the co-unit content increases. The samples with lower amount of PEBEK (40 and 20 mol%) are amorphous. The T g values tend to decrease with the reduction of the percentage of PEBEK units.

Preparation of aryl-substituted sulfonium by condensation of biphenyl sulfoxides with aromatic compound

Three kind of aryl-substituted tri-benzyl sulfonium salts [(4-phX)phSph2]PF6[X=S,O] were prepared by the condensation of biphenyl sulfoxide with biphenyl sulfide, biphenyl ether or 1,1’-biphenyl in the presence of polyphosphoric acid which can be used as dehydrate agent. The reaction condition was mild, such as reaction temperature between 40–50 °C, reactive time 2–3 h, the yield of 4-(phenylthio)triphenylsulfonium hexafluorophosphate was 87.6%. The three kind sulfonium salts show better curing character to epoxy resin.

Exploiting a basic chemosensitizing pharmacophore hypothesis. Part 1: Synthesis and biological evaluation of novel arylbromide and bicyclic chemosensitizers against drug-resistant malaria parasites

An exploratory series of novel arylbromide and bicyclic chemosensitizers (modulators) against chloroquine-resistant Plasmodium falciparum were designed and synthesized on the basis of a basic chemosensitizing pharmacophore hypothesis in malaria. ortho-Substituted bromo and biphenyl ether compounds displayed the best activity from the series.

Solvent assisted post-polymerization of PET

We have examined the influence of the solvent mixture diphenyl ether–biphenyl (DPE–BP) on the post-polymerization of poly(ethylene terephthalate) (PET) of intrinsic viscosity (IV=0.42 dL/g) in the swollen state and in solution, by following the IV increase and the end-group depletion. During the swollen state polymerization (SwSP) of thin disks (180 μm) at 195 °C, the initially rapid step growth polymerization slows dramatically beyond IV=1.2 dL/g in 5 h, and is unable to proceed beyond 1.4 dL/g. This appears to be related to the temporarily restricted mobility of the end groups due to the observed solvent induced crystallization, because sufficient reactive end groups can be directly detected, and further post-polymerization in melt state is possible. When limitations due to crystallization are eliminated by carrying out post-polymerization in solution at 250 °C, it proceeds to IV=1.8 dL/g in a single step. Since solution polymerization eliminates the requirement of handling fine PET particles, it offers an attractive route to high molecular weight PET, particularly when the solution can be directly used for further processing, e.g. into fibers.