PO3H2 Groups Research Articles

A comparative study on the influences of sulfonated- and phosphorated-graphene oxide on polyvinylidene fluoride cation-exchange membranes for electrodialysis

The –SO3H and –PO3H2 groups were grafted on graphene oxide (GO) by adding sulfuric acid and phosphoric acid at the same weight percentage, respectively. The physicochemical properties of the sulfonated GO (SGO) and phosphorated GO (PGO) were compared using different techniques. SGO and PGO were individually incorporated into the PVDF matrix (at the same wt%) to compare their effects on the properties of the resulting PVDF/SGO and PVDF/PGO cation-exchange membranes (CEMs). Membranes' characteristics including ionic conductivity and water content, area resistance, and the rate at which Na+ ions diffuse throughout the membranes changed considerably by altering the type of ion exchange sites, and more desirable values were obtained using PGO. Nevertheless, PVDF/SGO provided an ion exchange capacity (IEC) of 5.5 meq g−1, while it was about 1.7 times lower than PVDF/PGO (9.4 meq g−1). It also provided a promising ionic conductivity (17.24 mS cm−1), transport number (93.65 %), permselectivity (89.58 %), and low area resistance (2.7 Ω cm2), which exceeded those of the commercial CEMs such as Ralex. Moreover, PVDF/SGO exhibited desirable mechanical characteristics, and a low weight loss (2.4 %) and low resistance change (22.2 %) after 9 h being submerged in the Fenton reagent, however, these parameters were better for PVDF/PGO.

Phosphonic acid-imidazolium containing polymer ionomeric membranes derived from poly (phenylene oxide) towards boosting the performance of HT-PEM fuel cells

Phosphoric acid (PA)-dependent proton conductivity and polymer-offered mechanical properties are contradictory in high-temperature proton exchange membranes (HT-PEMs). Microphase separation strategy contributes to achieve a tradeoff between proton conductivity and mechanical properties. Herein, a kind of phosphonic acid-imidazolium containing polymer (PICP) ionomeric membranes, in which acidophilic (imidazolium) and acidophobic groups (-PO3H2) can be induced to form a microphase separation structure by PA, are firstly prepared. The acidophilic phase with adsorbed PA plays the role of proton conduction and the acidophobic phase can not only provides -PO3H2 group synergistically conduct protons but also largely maintains the intrinsic mechanical properties. As a result, the PICP ionomeric membranes with microphase separation structure possess high proton conductivity (48 mS cm−1, 160 °C) and satisfying mechanical strength (16.5 MPa) simultaneously at a moderate PA doping level (130 wt%). The fuel cell based on such HT-PEMs demonstrates a peak power density of 493 mW cm−2 and high voltage stability. This is the first report of phosphonic acid-imidazolium containing ionomeric membranes with satisfactory fuel cell performance and durability, representing a meaningful step towards practical HT-PEM fuel cells.

Porous organic polymer with high-density phosphoric acid groups as filler for hybrid proton exchange membranes

Developing sulfonated poly (ether ether ketone) (SPEEK)-based proton exchange membrane with both high proton conductivity and robust mechanical stability is desired for proton exchange membrane fuel cell (PEMFC). Here, a type of phosphoric acid porous organic polymer (PAPOP) with high‐density phosphoric acid (-PO3H2) groups and microporous structure was synthesized and incorporated into SPEEK matrix. The porous skeleton bonding -PO3H2 groups of PAPOP reduced the proton transfer activation energy by providing additional proton conduction pathways. The rigid backbone of PAPOP and its good compatibility with SPEEK increased the mechanical strength of the membrane. The hybrid membrane achieves greatly enhanced proton conductivity up to 417.0 mS cm−1 (80 °C, 100% RH) and high tensile strength of 120.6 MPa. The maximum power density of fuel cell with the hybrid membrane exhibits two times increase compared with the control membrane.

Enhancing Proton Conductivity and Durability of Crosslinked PBI-Based High-Temperature PEM: Effectively Doping a Novel Cerium Triphosphonic-isocyanurate

Acid doping is an effective way to enhance the proton conduction of high temperature polybenzimidazole (PBI) based proton exchange membranes (HTPEMs). To overcome the problem of acid leaching from the membranes, a cerium triphosphonic-isocyanurate (Ce-TOPT) proton conductor was synthesized and doped into a crosslinked PBI backbone (c-mPBI). The TOPT organic compound contains three –PO3H2 groups, which can be complexed with high valent metal ions (Ce4+/3+, Zr4+, Fe3+) to ensure its water-insolubility. Ce-TOPT(1:2) exhibited high ion exchange capacity (IEC, up to 2.2 meq. g−1) and good thermal stability. The organic-inorganic Ce-TOPT shown a high doping level in c-mPBI/CeTOPT membranes and consequently high proton conductivity of the membranes at high temperature and low relative humidity (RH). At 180 °C, the conductivity of c-mPBI/CeTOPT(50) could reach 0.125, 0.0885 and 0.0363 S cm−1 at 100% RH, 50% RH and anhydrous conditions, respectively. After water-washing for 48 h, the proton conductivity loss of c-mPBI/CeTOPT(50) was 4.6%. The good mechanical properties, proton conductivity, durability and membrane selectivity indicate that the crosslinked PBI-based membrane doped with Ce-TOPT is a potential candidate as HTPEMs.

Incorporating phosphoric acid-functionalized polydopamine into Nafion polymer by in situ sol-gel method for enhanced proton conductivity

Fabrication of novel composite proton exchange membranes (PEMs) with efficient proton transfer sites and homogeneous structure is crucial to PEM fuel cells but remains challenging. In this study, organic polydopamine sol is synthesized by a facile self-polymerization method and functionalized by abundant −PO3H2 groups, then the composite membrane is fabricated by mixing the functionalized polydopamine sol with Nafion followed by polycondensation of sol. The electrostatic interactions between functionalized polydopamine (FDPA) networks and Nafion matrix confer the composite membrane with excellent interfacial compatibility and enhanced physical, chemical stabilities. Due to the introduction of −PO3H2 groups, the hydrogen-bonded water bridges can be easily constructed and the energy penalty for proton transfer is greatly reduced. Meanwhile, the tradeoff effect between proton conductivity and fuel permeability is surmounted. The composite membrane displays the highest proton conductivity of 0.0314 S cm−1 (80 °C, 40% RH) and selectivity of 7.94 × 104 S s cm−3 (25 °C), which is 15.2 times and 4.5 times higher than those of the recast Nafion, respectively. Compared with recast Nafion, a 58.4% increase in maximum power density is achieved for the Nafion/FDPA-10 composite membrane.

Chemical interaction mechanism of 10-MDP with zirconia

Currently, the functional monomer 10-methacryloyloxy-decyl-dihydrogen-phosphate (10-MDP) was documented to chemically bond to zirconia ceramics. However, little research has been conducted to unravel the underlying mechanisms. This study aimed to assess the chemical interaction and to demonstrate the mechanisms of coordination between 10-MDP and zirconium oxide using 1H and 31P magic angle spinning (MAS) nuclear magnetic resonance (NMR) and two dimensional (2D) 1H → 31P heteronuclear correlation (HETCOR) NMR. In addition, shear bond-strength (SBS) tests were conducted to determine the effect of 10-MDP concentration on the bonding effectiveness to zirconia. These SBS tests revealed a 10-MDP concentration-dependent SBS with a minimum of 1-ppb 10-MDP needed. 31P-NMR revealed that one P-OH non-deprotonated of the PO3H2 group from 10-MDP chemically bonded strongly to zirconia. 1H-31P HETCOR NMR indicated that the 10-MDP monomer can be adsorbed onto the zirconia particles by hydrogen bonding between the P=O and Zr-OH groups or via ionic interactions between partially positive Zr and deprotonated 10-MDP (P-O−). The combination of 1H NMR and 2D 1H-31P HETCOR NMR enabled to describe the different chemical states of the 10-MDP bonds with zirconia; they not only revealed ionic but also hydrogen bonding between 10-MDP and zirconia.

Synthesis and application of a cyclopolymer bearing a propylphosphonic acid and a propylcarboxylic acid pendants in the same repeating unit

Diallyl[3-(diethoxyphosphoryl)propyl](3-ethoxycarbonylpropyl)ammonium chloride [ (CH2CH=CH2)2N+{(CH2)3PO3Et2} {(CH2)3CO2Et} Cl−], a new diallyl quaternary ammonium salt, has been cyclopolymerized to its cationic polyelectrolyte having pyrrolidine rings embedded in the polymer backbone. The polymer represents the first example of a cyclopolymer in which each repeating unit contains a propylphosphonate as well as a propylcarboxylate pendant. The hydrolysis of one, two or all the three-ester groups in the polymer afforded a series of pH-responsive macromolecules having identical degree of polymerization, which permitted a meaningful comparison of their solution behaviors. Apparent pKas of the triprotic repeating unit have been determined to be 2.52, 5.32 for 9.02 for the functionalities –PO3H2, −CO2H, and –PO3H−, respectively. The completely hydrolyzed polymer containing PO3H2 and CO2H groups demonstrated remarkable antiscalant behavior; at a concentration of 10 ppm, it inhibited the scaling of CaSO4 from its supersaturated solution with an inhibition efficiency of 100 % for over 500 min. The polymer may thus be exploited as an antiscalant in reverse osmosis plants.

N-Substituted amino acids as multifunctional additives used in cooling water. Part II: N-carboxymethyl and phosphonomethyl amino acids

The aim of research was to find additives with different capacities that can control the undesired corrosion and scale formation at the same time. Amino acids with different (carboxymethyl and/or phosphonomethyl) substituents were investigated to prove their multifunctional effectiveness. The most interesting parameters were the number of –COOH and –PO3H2 groups as well as the structure of the side chain in the amino acids. The experimental data proved that both the alkyl side chains (with or without additional carboxy and phosphonic groups) as well as the number of the ionizable substituents in the molecules influence the both efficacies.

Fluorescence light-up AIE probe for monitoring cellular alkaline phosphatase activity and detecting osteogenic differentiation.

Alkaline phosphatase (ALP) is an important monophosphate hydrolase during cell mineralization and osteogenic differentiation. Though traditional methods are provided for evaluating the ALP expression in the fixed and lysed cells, at present it is still challenging to monitor the ALP activity in living cells. In this work, three phosphorylated tetraphenylethylene (TPE) probes (TPE-PA, TPE-2PA and TPE-4PA) with different numbers of -PO3H2 groups were synthesized for monitoring the ALP activity. It was found that in aqueous solution, both the TPE-PA and TPE-2PA probes were highly sensitive to ALP. In the presence of ALP, they could be quickly hydrolysed, resulting in an aggregation-induced emission (AIE) to light up ALP. While in living cells, only TPE-2PA showed good cell penetrability and high fluorescence signal-to-noise ratio during osteogenic differentiation. This probe provides us a new strategy to screen the ALP activity in living stem cells for detecting osteogenic differentiation.

What Makes the Photocatalytic CO2 Reduction on N-Doped Ta2O5 Efficient: Insights from Nonadiabatic Molecular Dynamics.

Recent experimental studies demonstrated that photocatalytic CO2 reduction by Ru catalysts assembled on N-doped Ta2O5 surface is strongly dependent on the nature of the anchor group with which the Ru complexes are attached to the substrate. We report a comprehensive atomistic analysis of electron transfer dynamics in electroneutral Ru(di-X-bpy) (CO)2Cl2 complexes with X = COOH and PO3H2 attached to the N-Ta2O5 substrate. Nonadiabatic molecular dynamics simulations indicate that the electron transfer is faster in complexes with COOH anchors than in complexes with PO3H2 groups, due to larger nonadiabatic coupling. Quantum coherence counteracts this effect, however, to a small extent. The COOH anchor promotes the transfer with significantly higher frequency modes than PO3H2, due to both lighter atoms (C vs P) and stronger bonds (double vs single). The acceptor state delocalizes onto COOH, but not PO3H2, further favoring electron transfer in the COOH system. At the same time, the COOH anchor is prone to decomposition, in contrast to PO3H2, making the former show smaller turnover numbers in some cases. These theoretical predictions are consistent with recent experimental results, legitimating the proposed mechanism of the electron transfer. We emphasize the role of anchor stability, nonadiabatic coupling, and quantum coherence in determining the overall efficiency of artificial photocatalytic systems.

Enhanced proton conductivity of the hybrid membranes by regulating the proton conducting groups anchored on the mesoporous silica

Mesoporous silica submicrospheres with –NH2 groups or –PO3H2 groups on the outer surface, and –PO3H2 groups on the inner pore walls are prepared and designated as N–P–SiO2 and P–P–SiO2, respectively. Both kinds of silica submicrospheres are introduced into Nafion membrane matrix to fabricate hybrid membranes. The water uptake, membrane swelling properties, and proton conductivities at different temperatures and different relative humidities of the hybrid membranes are characterized. Proton conducting performances of the hybrid membranes are all enhanced compared to that of the pristine Nafion membrane, and the highest proton conductivity is 0.339 S cm−1 (115 °C, 100% RH). At 100% RH, Nafion/N–P–SiO2 membranes exhibit higher proton conductivities than the Nafion/P–P–SiO2 counterparts; while at low humidities, the proton conductivities of the Nafion/P–P–SiO2 membranes are enhanced more pronouncedly than those of the Nafion/N–P–SiO2 counterparts. The different increasing tendencies of the proton conducting performance could be attributed to the varied synergistic effects between the proton conducting groups introduced by the mesoporous silica and the groups anchored on the membrane matrix.

Synthesis and characterization of phosphorylated galactomannan: The effect of DS on solution conformation and antioxidant activities

Phosphorylated derivatives of galactomannan from guar gum (GG) with the degree of substitution (DS) of 0.35–0.52 were synthesized using POCl3/pyridine. FT-IR, 13C NMR and XPS results revealed that phosphorylation had occurred and C-6 substitution was predominant in phosphorylated guar gum (PGG). PGG showed an increase in Mw and more broad molar mass distribution in size exclusion chromatography (SEC) analysis. Higher reaction temperature (above 60°C) resulted in a higher MW value in PGG. It might be due to the cross-linking of polysaccharide chains by POCl3 via di-ester which was also supported by monosaccharide composition result. Results of MW−S2z1/2 showed a decrease in fractal dimension (df) values. DS had greater influence on its conformation in aqueous solution. The introduction of -PO3H2 groups improved significantly the stiffness of the chains due to the electrostatic effect. Furthermore, antioxidant experiments revealed that high DS could enhance the scavenging activities of radicals of PGG in vitro

Enhanced proton conductivity of hybrid membranes by incorporating phosphorylated hollow mesoporous silica submicrospheres

Hollow mesoporous silica submicrospheres (HMSS) are prepared with one-dimensional hexahedral mesopores regularly aligned along the radial directions of the silica shells. Both the outer and the inner surfaces of the mesoporous shells, as well as the mesopore walls are phosphorylated (PHMSS). Moreover, the lumen of PHMSS serves as accommodation for amino tris(methylene phosphonic acid) (ATMP) with large amount of phosphoric acid groups. Phosphorylated submicrospheres (PHMSS-ATMP) with multi-functionalities are thus prepared. After incorporating PHMSS-ATMP into chitosan (CS) matrix, the hybrid membranes were fabricated. The water uptake, anti-swelling properties and the proton conductivities are all enhanced. Particularly, the proton conductivities are considerably elevated and the highest proton conductivity is 9.4×10−2Scm−1 at 110°C 100% RH for the membrane with 7.5wt% of PHMSS-ATMP; the proton conductivities of CS/PHMSS-ATMP hybrid membranes at 80°C and low humidity are increased by two orders of magnitude compared to the pristine CS membrane. The enhanced performance could be attributed to the proton conducting groups introduced by PHMSS-ATMP: –PO3H2 groups are anchored on the surface of PHMSS-ATMP, and proton conducting channels could be formed by the mesopores of the silica shell, and the lumen could serve as acidic reservoirs.

A ruthenium(iii) phosphonate complex on polyallylamine functionalized carbon nanotube multilayer films: self-assembly, direct electrochemistry, and electrocatalysis.

On the basis of the electrostatic and donor-acceptor interactions between carboxylated multiwalled carbon nanotubes (MWCNT-COOH) and polyallylamine hydrochloride (PAH), PAH functionalized MWCNT multilayer films ({PAH/MWCNT-COOH}n) were readily formed on a glassy carbon (GC) electrode surface through a layer-by-layer (LBL) self-assembly method. Then, the PAH functionalized MWCNT multilayer films were used as a functional interface to effectively immobilize the ruthenium(iii) ethylenediamine-tetramethylene phosphonate (EDTMP-RuIII) complex through the strong electrostatic and/or hydrogen bonding interactions between -NH2 and -PO3H2 groups. Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive spectrum (EDS) mapping, and Raman measurements were used to characterize the self-assembly process, structure, composition and morphology of the EDTMP-RuIII/{PAH/MWCNT-COOH}n/GC electrode. In the EDTMP-RuIII/{PAH/MWCNT-COOH}n/GC electrode, the immobilized EDTMP-RuIII complex could directly exchange electrons with the substrate electrode and showed excellent electrocatalytic activity towards iodate reduction. Thus, the fabricated EDTMP-RuIII/{PAH/MWCNT-COOH}n/GC electrode could be used as an electrochemical sensor for iodate detection.

A new fluorometric turn-on assay for alkaline phosphatase and inhibitor screening based on aggregation and deaggregation of tetraphenylethylene molecules

Based on the consideration that compound 1 with a -PO3H2 group can be hydrolyzed into compound 3 which shows low solubility in aqueous solutions and thus aggregation can occur easily, a new fluorescence turn-on assay has been constructed for alkaline phosphatase (ALP) with compound 1. ALP at concentrations as low as 18 mUmL(-1) can be assayed with compound 1. Moreover, compound 1 has been successfully applied for ALP assay in living cells. Also, compound 1 is useful for screening inhibitors of ALP.

Enhanced proton conductivity of the proton exchange membranes by the phosphorylated silica submicrospheres

Two kinds of phosphorylated silica submicrospheres were synthesized and incorporated into the sulfonated poly(ether ether ketone) (SPEEK) matrices to fabricate the hybrid membranes. Phosphorylation was carried out by the reaction of phosphorus oxychloride and the epoxy groups on the silica surface introduced by glycidyl-silane (SiP-I) or poly(glycidyl methacrylate) (SiP-II). The length of the chains and the amount of phosphoric acid groups (–PO3H2) grafted on the silica surface were tuned by the above two different phosphorylation methods. The dispersion of SiP-II, anti-swelling and methanol resistant property of the SPEEK/SiP-II hybrid membranes were all enhanced. And the proton conductivity was increased by doping with both kinds of phosphorylated silica particles. While the SPEEK/SiP-I hybrid membranes with less amounts of –PO3H2 groups showed unexpectedly much higher proton conductivities than the SPEEK/SiP-II hybrid ones at the same loadings ranging from 5 wt% to 20 wt%, and the highest reached 0.335 S cm−1 at 60 °C and 100% RH. The result was tentatively discussed in terms of effective proton-conducting groups/sites instead of the absolute amount of acidic groups.

A study on the effect of different chemical routes on functionalization of MWCNTs by various groups (-COOH, -SO3H, -PO3H2)

Pristine multiwall carbon nanotubes [MWCNTs] have been functionalized with various groups (-COOH, -SO3H, -PO3H2) using different single- and double-step chemical routes. Various chemical treatments were given to MWCNTs using hydrochloric, nitric, phosphoric, and sulphuric acids, followed by a microwave treatment. The effect of the various chemical treatments and the dispersion using a surfactant via ultrasonication on the functionalization of MWCNTs has been studied. The results obtained have been compared with pristine MWCNTs. Scanning electron microscopy, energy dispersive X-ray [EDX] spectroscopy, and transmission electron microscopy confirm the dispersion and functionalization of MWCNTs. Their extent of functionalization with -SO3H and -PO3H2 groups from the EDX spectra has been observed to be higher for the samples functionalized with a double-step chemical route and a single-step chemical route, respectively. The ID/IG ratio calculated from Raman data shows a maximum defect concentration for the sample functionalized with the single-step chemical treatment using nitric acid. The dispersion of MWCNTs with the surfactant, Triton X-100, via ultrasonication helps in their unbundling, but the extent of functionalization mainly depends on the chemical route followed for their treatment. The functionalized carbon nanotubes can be used in proton conducting membranes for fuel cells.

Retracted Article: Synthesis of a novel type of chiral salen Mn(iii) complex immobilized on crystalline zinc poly(styrene-phenylvinylphosphonate)-phosphate (ZnPS-PVPP) as effective catalysts for asymmetric epoxidation of unfunctionalized olefins

The hypothesized structure of ZnPS-PVPP (a) signifies that the two or more neighboring –PO3H2 groups are in same colloidal precipitation; while (b) signifies that the two neighboring –PO3H2 groups are in different colloidal precipitation.

One, two, and three methylene phosphonic acid groups (–CH2PO3H2) on a mesitylene ring: synthesis, characterization and aspects of supramolecular aggregation

The ease of substitution of –CH2Br group on the mesitylene ring in a stepwise manner has been exploited to prepare mesitylene mono-, bis-, and tris-methylene phosphonic acids C6H2Me3(CH2PO3H2) (1), C6HMe3(CH2PO3H2)2 (2), and C6Me3(CH2PO3H2)3 (3) in 80–90% yield, through a Michaelis–Arbuzov reaction followed by acid hydrolysis. Compounds 1–4 have been characterized by analytical and spectroscopic (IR, NMR, and MS) techniques. The X-ray structural investigations on all the three compounds reveal that the central mesitylene ring is a robust platform for hosting multiple methylene phosphonic acid groups. Mesitylene mono-methylene phosphonic acid 1, which can be considered as the sterically encumbered modification of benzyl phosphonic acid, interestingly associates as a one-dimensional tubular structure through extensive O–H⋯O hydrogen bonding between adjacent –PO3H2 groups, albeit with no such interactions between the tubes due to the highly hydrophobic nature of the surface. The X-ray structure of mesitylene-1,3-diphosphonic acid 2 reveals that the molecules exhibit a syn-orientation of the –CH2PO3H2, which are involved in extensive P–OH⋯O hydrogen bonding to result in a two-dimensional layered structure. The presence of three –PO3H2 units on the same side of the mesitylene ring in 3 results in a three-dimensional framework solid. The present studies clearly reveal a linear relationship between the dimensionality of the supramolecular structure and the number of phosphonic acid moieties on the mesitylene ring.

Preparation and Interfacial Properties of Phosphonic Acid-Terminated Self-Assembled Monolayers on Gold Surface

The preparation and interfacial properties of self-assembled monolayers (SAMs) of 3-mercaptopropylphosphonic acid [HS−(CH2)3−PO3H2, MPPA] adsorbed on Au surfaces have been systematically investigated with the electrochemical method, X-ray photoelectron spectroscopy (XPS), and surface-enhanced internal reflection infrared spectroscopy measurements. An improved rinse method (base−acid rinse protocol) is presented to prepare the MPPA monolayers free of unbound MPPA thiols. Experimental results show that the effect of the degree of dissociation of −PO3H2 groups on the compactness of MPPA−SAMs is nonlinear possibly because of hydrogen bond interaction and the dibasic nature and hydrophilicity of the −PO3H2 groups. The effects of pH and the electric field on the surface charge of MPPA−SAMs are investigated.