Pendant Phosphonate Groups Research Articles

Benzothiadiazole-based conjugated polyelectrolytes for interfacial engineering in optoelectronic devices

Abstract Polar semiconducting polymers based on a conjugated polymer backbone endowed with chemically anchored polar groups on the side chains have proved to be particularly interesting as optimization layer at organic/cathode interface in optoelectronic devices. In particular, the pendant phosphonate groups impart water-alcohol solubility allowing easy solution processing, and improve electron injection thanks to both a favorable interfacial dipole of phosphonate groups and an intense coordination interaction between the phosphonate groups and Al cathode. In this work we synthesize alternating fluorene-benzothiadiazole copolymers by proposing a post-polymerization reaction to insert the phosphonate groups. Thanks to this approach it is possible to use standard Suzuki coupling conditions, simplifying the process of synthesis, purification and characterization. The polymer Poly[9,9-bis(6′-diethoxylphosphorylhexyl)-alt-benzothiadiazole] (P2), is tested in conventional organic solar cells as cathode interfacial layers showing, with respect to the control device, an increasing of all the photovoltaic parameters, with a final power conversion efficiency that reaches 5.35% starting from 4.6%. The same trend is observed for multilayered polymer light-emitting diodes with an external quantum efficiency of the P2-based PLED enhanced of 1.5 times with respect to the basic devices with bare Al cathode, and negligible roll-off efficiency. The synergic effects of energy gap modulation and of polar phosphonated pendant functionalities of P2 are compared with the corresponding fluorene-based polar homopolymer. Our results show that, not only a proper selection of side functionalities, but also the tailoring of the energy gap of cathode interfacial materials (CIMs) is a possible effective strategy to engineer cathode of different optoelectronic devices and enhance their performance.

Gallium(III) chelates of mixed phosphonate-carboxylate triazamacrocyclic ligands relevant to nuclear medicine: Structural, stability and in vivo studies

Three triaza macrocyclic ligands, H6NOTP (1,4,7-triazacyclononane-N,N′,N″-trimethylene phosphonic acid), H4NO2AP (1,4,7-triazacyclononane-N-methylenephosphonic acid-N′,N″-dimethylenecarboxylic acid), and H5NOA2P (1,4,7-triazacyclononane-N,N′-bis(methylenephosphonic acid)-N″-methylene carboxylic acid), and their gallium(III) chelates were studied in view of their potential interest as scintigraphic and PET (Positron Emission Tomography) imaging agents. A 1H, 31P and 71Ga multinuclear NMR study gave an insight on the structure, internal dynamics and stability of the chelates in aqueous solution. In particular, the analysis of 71Ga NMR spectra gave information on the symmetry of the Ga3+ coordination sphere and the stability of the chelates towards hydrolysis. The 31P NMR spectra afforded information on the protonation of the non-coordinated oxygen atoms from the pendant phosphonate groups and on the number of species in solution. The 1H NMR spectra allowed the analysis of the structure and the number of species in solution.31P and 1H NMR titrations combined with potentiometry afforded the measurement of the protonation constants (log KHi) and the microscopic protonation scheme of the triaza macrocyclic ligands. The remarkably high thermodynamic stability constant (log KGaL=34.44 (0.04) and stepwise protonation constants of Ga(NOA2P)2− were determined by potentiometry and 69Ga and 31P NMR titrations. Biodistribution and gamma imaging studies have been performed on Wistar rats using the radiolabeled 67Ga(NO2AP)− and 67Ga(NOA2P)2−chelates, having both demonstrated to have renal excretion. The correlation of the molecular properties of the chelates with their pharmacokinetic properties has been analysed.

Non-Amide Kinetic Hydrate Inhibitors: Investigation of the Performance of a Series of Poly(vinylphosphonate) Diesters

The kinetic hydrate inhibitor (KHI) performances of a series of poly(dialkyl vinylphosphonate)s (PDAVPs) containing pendant phosphonate groups fully esterified with two identical alkyl chains have been assessed by conducting a suite of slow constant cooling tests at 76 bar in steel rocking cell equipment using a synthetic natural gas (SNG) that preferably forms structure II gas hydrates. The KHI performances of three PDAVPs, of roughly the same molecular weights (28–38 kDa), comprising methyl (M), ethyl (E,) and isopropyl (IP) groups, respectively, were evaluated. As a result, the following ranking was disclosed: P(DIPVP) > P(DEVP) > P(DMVP). The diisopropylated P(DIPVP) homopolymer gave an average onset temperature from 10 experiments of To of 8.3 °C compared to 17.3 °C with deionized water and no additive. The good performance is likely related to the low cloud point (1 wt % solution in deionized water), which was measured to be 18 °C. Three ethylated P(DEVP)s, with molecular weights in the range 30–60 kDa, were tested for KHI performances. The two higher molecular weight samples gave the best performance, which we surmise is related more to the lower cloud point of these samples than the molecular weight. A P(DMVP:DIPVP) copolymer with a high cloud point showed weak KHI effect (To = 13.1 °C).

Copolyfluorenes containing partially hydrolyzed phosphonate pendant groups: synthesis, characterization and application as electron injection layers for enhanced electroluminescence of PLEDs

Copolyfluorenes containing pendant phosphonate groups or partially hydrolyzed phosphonate groups were applied as electron-injection layers to significantly enhance the device performance.

Phosphonoethylated Polyglycidols: A Platform for Tunable Enzymatic Grafting Density

Polyether graft polyester copolymers with pendant diethylphosphonatoethyl groups (DEPE), P(GDEPE-co-(G-g-eCL)-co-G), were prepared by enzymatic grafting of e-caprolactone from polyglycidols carrying 0, 15.4, and 38.5% of DEPE groups. The graft copolymers were characterized by 1H, 13C, and 31P NMR spectroscopy and SEC analysis. Despite the steric bulk of the DEPE residues, high initiation efficiencies (IE) of the phosphonoethylated macroinitiators could be achieved by appropriate choice of the reaction parameters such as lipase and monomer concentration. Depending on the degree of functionalization of polyglycidol with phosphonate residues (FDEPE), the IE is tunable in a wide range from 31 to 81%. The graft copolymers with pendant phosphonate groups are promising candidates for hydrolytically degradable biomaterials, since all building blocks are biocompatible and/or biodegradable.

New fluorinated polymers bearing pendant phosphonic groups for fuel cell membranes: Part 1 synthesis and characterizations of the fluorinated polymeric backbone

Radical copolymerizations of chlorotrifluoroethylene (CTFE) with vinyl ethers such as 2-chloroethyl vinyl ether (CEVE) and ethyl vinyl ether (EVE) were performed at 75 °C in the presence of peroxide initiator. Three copolymers were obtained and characterized by means of both NMR and elemental analysis. Then, the chlorine atoms in the side chains were converted into iodine atoms by nucleophilic substitution, which was monitored by 1H NMR spectroscopy. A series of five copolymers with different amounts of iodine atoms in the side chains were thus obtained. These copolymers exhibited molecular weight values of about 25,000 g mol −1, and the thermal analysis of the copolymers showed a starting degradation from about 220 °C. The T g values were in the range of 34–41 °C and showed a linear dependence versus the content of iodine atoms.

Click-chemistry-based bis-triazolylpyridine diphosphonate ligand for the sensitized luminescence of lanthanides in the solid state within the layers of γ-zirconium phosphate

The synthesis by means of ‘click’ chemistry of a new ligand bearing the bis-triazolylpyridine motif and pendant phosphonate groups is described. The topotactic phosphate/phosphonate exchange of the ligand into gamma-zirconium phosphate led to an organic–inorganic-layered material which revealed an excellent matrix to achieve the efficient sensitization of emitting lanthanides.

Phosphonate-functionalized ORMOSIL coatings for magnesium alloys

Hybrid organically modified silicates, or ORMOSIL materials, with covalently attached pendant phosphonate groups were processed by a sol–gel method. A hydrolysis and condensation route was used involving a phosphonato-silane and resultant films were evaluated as prospective coatings for magnesium AZ31B alloy substrates. The inclusion of phosphonate functionalities into the coating matrix was achieved by a co-condensation of the phosphonato-silane with other organo-functional silanes followed by blending the resultant phosphonate-functionalized silicate oligomers with another sol–gel matrix material to form an interpenetrating network structure. The effect of synthesis composition on the hydrophobic/hydrophilic balance and film barrier properties was examined by several methods, including constant immersion and electrochemical tests. The observed enhancement in corrosion protection properties was attributed to a combination of the barrier properties of the organo-silicate matrix along with strengthening of the coating/substrate interface due to chemical bonding of the phosphonate groups to the metal surface.

A Water-Soluble Poly(phenylene ethynylene) with Pendant Phosphonate Groups. Synthesis, Photophysics, and Layer-by-Layer Self-Assembled Films

This paper reports the synthesis, optical, and thin-film-forming properties of a new water-soluble poly(phenylene ethynylene) that features phosphonate solubilizing groups. The new polymer, PPE-PO3-, is prepared by a synthetic route that involves initial preparation of a neutral analogue polymer in which the phosphonate groups are in the form of dibutyl esters. The neutral polymer is converted to the water-soluble form by cleavage of the phosphonate ester groups using (CH3)3SiBr. PPE-PO3- absorbs in the blue of the visible region and features a moderately intense fluorescence. The absorption and fluorescence of the polymer vary strongly with pH, an effect which is believed to arise because the polymer exists in a strongly aggregated form at low pH and in a relatively unaggregated state at high pH. Ultrathin multilayer films of the PPE-PO3- are deposited by the layer-by-layer (LbL) method using either the cationic polyelectrolyte poly(diallyldimethylamine) or Zr(IV) as deposition “partners”. Absorption spe...

The effect of phosphonate-based growth modifiers on the morphology of hematite nanoparticles formed via acid hydrolysis of ferric chloride solutions

The effect of organic phosphonate-based additives on α-Fe2O3 (hematite) crystallization via the forced hydrolysis of ferric chloride solutions has been studied using a range of additives containing 2, 3 or 4 pendant phosphonate groups. The hydrolysis reactions were carried out at pH 1.1 with an iron concentration of 0.01 mol L−1, and with Fe ∶ additive ratios ranging from >8000 ∶ 1 down to 200 ∶ 1. In the absence of additive, the hematite particles are very uniform rhombic single crystals, with an average length of ≈100 nm. In the presence of phosphonates the particles become hexagonal, with the additives acting by inhibiting growth at (2) faces. At Fe ∶ additive ratios lower than about 200 ∶ 1, hematite formation is completely inhibited. Our results are consistent with a mechanism in which the akaganeite and hematite phases may both precipitate from the ferric chloride solution, with akaganeite apparently forming more rapidly than hematite. Inhibition of hematite formation by addition of the phosphonate additive can lead to β-FeOOH (akaganeite) being the dominant product phase, provided the concentration of Fe3+ in solution is above the equilibrium solubility of the akaganeite phase.

Synthesis and characterization of phosphonate‐containing polysiloxanes

AbstractPhosphonate‐functionalized polysiloxanes have been prepared with a new siloxane/phosphonate monomer. The reaction of 3‐chloropropylmethyldimethoxysilane with trimethylphosphite or triethylphosphite produces several new monomers containing pendant phosphonate groups. Copolymerization with dimethyldimethoxysilane has produced polymers soluble in most organic solvents. The acid hydrolysis of the phosphoryl esters has produced hydrophilic siloxane polymers containing phosphonic acid groups. The thermal properties of the polymers and several related small molecules have been compared with thermogravimetric analysis. Both the monomers and the resulting polymers have been characterized with 1H, 13C, 31P, and 29Si NMR. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 48–59, 2003

Bacterial adhesion to polyurethane surfaces in the presence of pre-adsorbed high molecular weight kininogen.

The factors which affect the adherence of a bacteria cell to the surface of a biomaterial include the surface chemistry of the cell and material, as well as the composition of the adsorbed protein layer when the biomaterial is exposed to circulating blood. In an effort to better understand the mechanisms by which bacteria adhere to such surfaces, and specifically to determine the effects of high molecular weight kininogen on bacterial adhesion, experiments were performed in which the attachment of Staphylococcus aureus was directly observed on glass and on a series of functionalized polyurethanes. These surfaces had been pre-adsorbed with various concentrations of high molecular weight kininogen and fibrinogen. Attachment was observed using a radial flow chamber, in which shear stress varied inversely with radial distance. Protein adsorption studies were also performed using 125I labeled fibrinogen to investigate the relationship between surface chemistry, protein adsorption, and bacterial attachment. Bacterial attachment was significantly decreased when the glass surface was pre-adsorbed with high molecular weight kininogen--either alone, or following adsorption of fibrinogen. High molecular weight kininogen thus exhibited anti-adhesive effects. On polyurethane surfaces pre-adsorbed with fibrinogen, kininogen, and albumin, the highest bacterial attachment was found on the base polyurethane, while significant decreases were seen on the hydrophilic polyurethanes. In addition, it was found that the surface with the least bacterial attachment and fibrinogen deposition was the polyurethane with pendant phosphonate groups.