Phenylphosphonic Acid Research Articles

Wheel‐Shape Heterometallic Ti10M2‐oxo Clusters (M = Ni, Co) with Effective Visible Light Absorption

Summary of main observation and conclusionIn order to make visible light harvest crystalline polyoxo‐titanium clusters, we initially used transition metal pivalate complexes in this system and prepared successfully two isostructural compounds, [Ti10M2(PPO)4(μ3‐O)8(μ2‐O)4(PA)12(MeCN)4]·4HPA (PPOA = phenylphosphonic acid, HPA = propionic acid, M = Ni, PTC‐52‐Ni; M = Co PTC‐52‐Co). Single‐crystal X‐ray diffraction study showed that these two complexes possessed wheel‐shape heterometallic Ti10M2‐oxo clusters. The absorption bands of these two compounds shift effectively toward the visible‐light region. Furthermore, their photocurrent response has also been studied.

Molecular anchoring to oxide surfaces in ultrahigh vacuum and in aqueous electrolytes: phosphonic acids on atomically-defined cobalt oxide.

In this work, we investigated the interaction of phenylphosphonic acid (PPA, C6H5PO3H2) with atomically-defined Co3O4(111) thin films, grown on Ir(100), under ultrahigh vacuum (UHV) conditions and in the electrochemical environment. In the first step, we employed infrared reflection absorption spectroscopy (IRAS) and followed the formation of a saturated monolayer (380 K) in UHV. We observed that the binding motif changes from a chelating tridentate in the sub-monolayer regime to a chelating bidentate at full monolayer coverages. In the electrochemical environment, we analyzed the interaction of PPA with the same Co3O4(111) surface by electrochemical infrared reflection absorption spectroscopy (EC-IRRAS) (0.3 VRHE-1.3 VRHE). When adsorbed at pH 10 from an ammonia buffered aqueous solution, PPA binds to the surface in form of a fully deprotonated chelating bidentate. With increasing electrode potential, we observed two fully reversible processes. At low buffer concentration, protons are released upon oxidation of surface Co2+ ions and lead to protonation of the anchored phosphonates. At high buffer concentration, most of the protons released are accepted by NH3. Simultaneously, the surface phosphonate changes its adsorption motif from bidentate to tridentate while adopting a more upright geometry.

Synthesis and structural characterization of a dumbbell-like phenylphosphonate-stabilized Ti7-oxide cluster.

In recent years, crystalline polyoxotitanium clusters (PTCs) have attracted increasing attention as a new kind of promising crystalline material. In this work, a PTC stabilized by phenylphosphonate ligands, i.e. hexa-μ-isopropanolato-hexaisopropanolatodi-μ3-oxido-hexa-μ3-phenylphosphonato-heptatitanium tetrahydrate, [Ti7(μ3-O)2(O3P-Phen)6(OiPr)12]·4H2O [PTC-54; H2O3P-Phen is phenylphosphonic acid, C6H5PO(OH)2, and HOiPr is isopropanol, C3H7OH], was obtained successfully through a facile one-step solvothermal reaction. The dumbbell-like core structure of PTC-54 can be described as two trinuclear {Ti3(μ3-O)} building units combined together by six phenylphosphonate ligands and one additional Ti atom, giving rise to a Ti7 cluster. Adjacent molecules of PTC-54 are further connected through π-π interactions between the phenyl groups to form a supramolecular one-dimensional chain.

Hybrid organophosphonic-silane coating for corrosion protection of magnesium alloy AZ91: The influence of acid and alkali pre-treatments

This work reports the development of environmentally friendly coatings for the protection against corrosion of AZ91 magnesium alloy substrates. As a novelty, the synergic combination of the use of silica precursors and phosphonic acid molecules has been investigated for first time in the protection of AZ91 Mg alloy. Hybrid films have been prepared by the sol–gel synthesis using tetraethoxysilane (TEOS) and methylmethoxysilane (MTMS), as co-monomers; and 1,2‑diaminoethanetetrakismethylenephosphonic acid (EDTPO) and phenylphosphonic acid (PhPA), as adhesion promoter molecules. In order to improve the homogenous deposition of the silica network, several chemical pre-treatments were approached. The highest corrosion resistance, as determined by electrochemical impedance spectroscopy (EIS), has been observed for the AZ91 Mg alloy submitted to a passivation treatment with Na3PO4/NaOH, before the sol-gel deposition. Particularly, the addition of low concentrations of EDTPO, which contains four active phosphonic groups, improves considerably the coating's resistance, as demonstrated by EIS, due to the formation of multiple covalent interactions with silica network and the passivated metal substrate.

A series of zirconium-oxo cluster complexes based on arsenate or phosphonate ligands

A series of zirconium-oxo cluster complexes have been prepared by the reaction of Zr(OnPr)4 and arsenate or phosphonate ligands, namely, Zr6(μ3-O)2(4-aPhaa)4(OnPr)12 (Zr6-1, 4-aPhaa = 4-aminophenylarsonic acid), Zr6(μ3-O)2(tbpa)4(OnPr)12 (Zr6-2, tbpa = tert-butylphosphonic acid), H2[Zr6(μ3-O)(μ2-O)(tbpa)5(OnPr)12] (Zr6-3), and H4[Zr10(μ4-O)4(μ3-O)4(ppa)4(OnPr)20] (Zr10, ppa = phenylphosphonic acid). These complexes have been structurally characterized by the single-crystal X-ray diffraction. Interestingly, the {Zr10} cluster contains a [Zr10O4]32+ supertetrahedron core stabilized by the phosphate groups. In addition, thermal stabilities and phase purities were also investigated in detail.

Synthesis of Stable Hierarchical MIL-101(Cr) with Enhanced Catalytic Activity in the Oxidation of Indene

Nowadays, the controllable synthesis of stable hierarchical metal–organic frameworks (MOFs) is very important for practical applications, especially in catalysis. Herein, a well-known chromium–benzenedicarboxylate metal–organic framework, MIL-101(Cr), with a stable hierarchical structure, was produced by using phenylphosphonic acid (PPOA) as a modulator via the hydrothermal method. The presence of phenylphosphonic acid could create structural defects and generate larger mesopores. The synthesized hierarchical MIL-101(Cr) possesses relatively good porosity, and the larger mesopores had widths of 4–10 nm. The hierarchical MIL-101(Cr) showed significant improvement for catalytic activity in the oxidation of indene. Further, the presence of a hierarchical structure could largely enhance large dye molecule uptake properties by impregnating.

Three Silver Nests Capped by Thiolate/Phenylphosphonate.

Introducing phenylphosphonic acid (H2 PPA) into the Ag/tBuSH assembly system has produced a family of nanoscale-sized, high-atom number, silver thiolate/PPA nests (SD/Ag45 a, SD/Ag66 a, and SD/Ag73 a) with impressive core-shell features. SD/Ag45 a is a 45-atom ellipsoid comprised of an Ag36 shell trapping an Ag9 S2 three-bladed rotor inside. SD/Ag66 a comprises an inner rod-like Ag20 core and an outer Ag44 shell, giving a 64-atom nest. These Ag64 nests are further extended by Ag(CN)2 linkers to form a one-dimensional chain structure. SD/Ag73 a is a three-shell 73-nucleus silver nest with a central silver atom enclosed in a rhombicuboctahedron of 24 silver atoms, which is itself enclosed in the outermost shell of a rectified version of a 48-Ag octahedral Goldberg 2,0 cage. The solution behaviors and optical absorption properties of the three nests are described in detail. Of note, SD/Ag45 a and SD/Ag73 a emit in the near-infrared region and show different luminescent thermochromic behavior. This work demonstrates that the participation of H2 PPA strongly influences the structures of silver thiolate nests, thus providing a new route to fabricate and modify them in a more rational way.

Corrosion Assessment of Zinc-Rich Primers Containing Polyaniline and the Effect of Acid as a Dopant

We investigated how adding the dopant acid for polyaniline (PAni)-containing zinc-rich primers (ZRPs) can influence the resulting ZRP’s corrosion performance. Two organic acids (camphorsulfonic [CS] and phenylphosphonic acid [H2PP]), and two inorganic acids (phosphoric [H2PO4] and hydrochloricacid [HCl]) were tested and the different PAni-modified ZRPs exhibited differences in their cathodic protection and barrier mechanisms during exposure to a 3.5 wt% NaCl solution. The hydrochloricacid-doped PAni-containing ZRP had the best anticorrosion properties in terms of the zinc particle interfacial activation (sacrificial) and coating’s barrier properties. Corrosion resistance of the coating systems can be ranked as PAni-Cl > PAni-H2PO4 > PAni-HPP ≥ PAni-CS. The corrosion assessment of these coatings can be explained in terms of three stages: the activation stage of the zinc particles, the competition stage, and the steady state stage.

Reaction between Pyrocatechol and N,N,N',N'-Tetraethylphenylphosphonous Diamide

The reaction between pyrocatechol and N,N,N',N'-tetraethylphenylphosphonous diamide was studied. It was found that the main reaction products are bisphosphorylated pyrocatehol and and the product of intramolecular cyclization, ester of pyrocatechol and phenylphosphonic acid.

Phosphonic Acids on Well-Ordered CoO Surfaces: The Binding Motif Depends on the Surface Structure

In this work, we investigate the interaction of deuterated phenylphosphonic acid (DPPA, C6H5PO3D2) with two different well-ordered cobalt-oxide thin films, CoO(111) and CoO(100), grown on Ir(100). We applied coverage-dependent infrared reflection absorption spectroscopy (IRAS) and temperature-programmed (TP)-IRAS under ultrahigh vacuum conditions to study surface reactions, film growth, and thermal stability, both in monolayer and multilayer regimes. The results are compared to our previous studies on Co3O4(111).(1) In the multilayer regime, amorphous multilayer films of DPPA are formed at a low temperature (180 K), which are very similar on all surfaces. At 250 K, the multilayer films crystallize, leading to changes in the molecular orientation relative to the surface. Above 340 K, the multilayer desorbs while only the chemically anchored monolayer remains on the surface. The monolayer films on all three surfaces are stable up to at least 400 K. Coverage and binding geometry, however, depend sensitively ...

Electrochemical, spectroscopic and theoretical studies on redox speciation of neptunium with phenylphosphonic acid

Neptunium (Np) is a key element of concern for the safety aspects regarding the reprocessing and handling of spent nuclear fuel owing to its long half life (t1/2 = 2.14 × 106 years). Np can exist in several oxidation states in aquatic environments depending on the surrounding conditions in which it exists. The +5 oxidation state of Np as NpO2+ is the most stable and least binding moiety that can migrate in aquatic arena to far away positions from its source of origin. Humic acids, which are omnipresent in aquifers, are the major source of binding for the actinides including Np to facilitate their migration and transportation phenomenon. Probing the systematic knowledge of neptunium (Np), such as, speciation and coordination as function of its oxidation states in presence of chelating agents is essential aspect of its solution chemistry. The present study aimed at investigating the redox and complexation of Np with phenylphosphonic acid (PhPO3H2) (PPA) as mimic for binding of aromatic phosphorus functionalities in humic substances by using electrochemical and UV–Visible absorption spectroscopy and density functional calculations. The cyclic voltammetric measurement indicates the complexation of both oxidation states (V & VI) of Np with [PhPO3]2−. The presence and stability region (via Eh-pH plot) of new species of Np-PhPO3 in two different oxidation states (V & VI) in aqueous solution at varying physicochemical conditions are identified. The kinetics for reduction of Np complexes in different oxidation states are explored by evaluation of heterogeneous electron-transfer kinetic (D0, ko and α) parameters by cyclic voltammetric results. The spectral parameters, namely λmax and its molal extinction coefficient (ε) are obtained from UV–Visible spectrophotometric measurements and are found to be 988.2 nm and 302 ± 8 mol−1 L cm−1 respectively. The electrochemical as well as UV–Visible spectrophotometric measurements showed the formation of 1:1 complex only and the stability constant (logβ) obtained for the same from both the methods found to be in agreement with each other. Density Functional Theory (DFT) calculations are carried out to optimize the geometries of Np-PhPO3 complex for the Np in +5 and +6 oxidation states with [PhPO3]2− in mono and bidentate mode to identify the most probable coordination mode for complex formation.

Crystal Orientation of Poly(l-Lactic Acid) Induced by Magnetic Alignment of a Nucleating Agent.

The orientation of poly(l-lactic acid) (PLLA) crystals was controlled through crystal growth from a magnetically oriented nucleating agent, phenylphosphonic acid zinc (PPAZn). The one-dimensional magnetically oriented microcrystal array of PPAZn microcrystals revealed the relationship between the magnetization and crystallographic axes in the PPAZn crystal. The PPAZn microcrystals were homogeneously dispersed in PLLA via melt mixing, which decreased the molecular weight of the PLLA component due to degradation. The PPAZn microcrystals in the molten PLLA were uniaxially aligned under an 8-T static or rotating magnetic field. The wide-angle X-ray diffraction and small-angle X-ray scattering patterns of the PPAZn/PLLA composite films crystallized under each magnetic field showed that the PLLA lamellae grew from the surface of the PPAZn microcrystals, which were uniaxially oriented along the easy- or hard-magnetization axis, with the c-axis of PLLA parallel to the bc-plane of PPAZn. It was also suggested that the greater nucleating effect of PPAZn on PLLA was derived not from geometrical matching, but from factors such as favorable interactions and/or the plate-like shape of the microcrystal.

The Effect of Composite Nucleating Agent on the Crystallization Behavior of Branched Poly (Lactic Acid)

Composite nucleating agent (CNA) consisting of zinc oxide as a crystallization promoter and phenylphosphonic acid zinc salt (PPZn) as an heterogeneous nucleation agent was employed to improve the crystallization behaviors of branched poly (lactic acid) (B-PLA) which was prepared by use of multi-functional epoxy-based chain extender (CE). The differential scanning calorimeter results showed that the crystallinity and crystallization temperature of prepared B-PLA/CNA were higher than that of linear poly (lactic acid) (L-PLA) and B-PLA at a high cooling rate. The corresponding phenomena of heterogeneous nucleation of B-PLA/CNA were observed by means of polarized optical microscope. The crystalline mechanism research results show that the degradation reaction and chain extending reaction were occurred simultaneously after the addition of CE and CNA into the PLA, PPZn as an effective nucleation points could increase the nucleation density and the degraded short molecular chains with higher chain mobility would improve crystal growth during the crystallization of the branched PLA. Non-isothermal cold crystallization kinetics of various B-PLA with different content of CNA was studied. The corresponding result showed that the crystallinity and crystallization rate increased obviously with the CNA content greater than or equal to 5phr, as well as the crystallization time decreased. The similar experimental results of non-isothermal and isothermal melt crystallization kinetics also showed that CNA had a significant impact on crystallization behavior of B-PLA.

Efficient catalytic transfer hydrogenation of biomass-based furfural to furfuryl alcohol with recycable Hf-phenylphosphonate nanohybrids

An acid-base bifunctional nanohybrid phenylphosphonic acid (PhP) - hafnium (1:1.5) was synthesized through assembly of PhP with HfCl4 for catalytic transfer hydrogenation of furfural (FUR) to furfuryl alcohol (FFA) using 2-propanol as both reaction solvent and hydrogen donor source. An FFA yield of 97.6 % with formation rate of 9760 μmol g−1 h−1 at 99.2 % FUR conversion was obtained with the reaction system at 120 °C for 2 h reaction time. Activation energy (Ea) was estimated to be 60.8 kJ/mol with respect to FUR concentration, which is comparable with or even lower than Ea values attained over metal catalysts. The pronounced catalytic activity of PhP-Hf (1:1.5) is attributed to its moderate acidity and relatively strong basicity. The PhP-Hf (1:1.5) catalyst was demonstrated to maintain its activity for five consecutive reuse cycles.

Phosphate-imprinted magnetic nanoparticles using phenylphosphonic acid as a template for excellent recognition of tyrosine phosphopeptides

The tyrosine phosphorylation of proteins and peptides plays a vital role in cell signal transduction pathways, and it is very important to assay them for understanding their action mechanism. Due to the low levels of the tyrosine phosphopeptides (pTyr) in cells, it is a challenge to enrich them with traditional sorbents, therefore, development of specific and selective sorbents is urgent and necessary. In this work, the phosphate-imprinted magnetic nanoparticles (PMNPs) to enrich the pTyr with high efficiency and selectivity have been fabricated using the phenylphosphonic acid as a template for the "epitope" of pTyr. The magnetic nanoparticles have been functionalized with TiO2 and then the imprinting silica shells have been coated on the surface of the functional core to obtain the PMNPs sorbents. The PMNPs can obviously shorten the enrichment time and improve the adsorption efficiency for pTyr, and the epitope imprinting films provide an excellent selective recognition ability to target. The recognition capability of PMNPs for pTyr is 90.3 μg/mg and the imprinting factor of the sorbents can reach 24.4. The results indicate that the PMNPs can enrich the pTyr from the tryptic digest of β-casein samples with high specificity, and the spiking recoveries of the pTyr range from 85.1% to 93.8% with the RSD from 0.04 to 3.73. With the high adsorption capacity, rapid separation, excellent specificity and recyclability, the PMNPs sorbents show great potential for analysis of the phosphorylation of peptides in biological and medical fields.

Phosphonic Acids on an Atomically Defined Oxide Surface: The Binding Motif Changes with Surface Coverage.

We have studied the anchoring mechanism of a phosphonic acid on an atomically defined oxide surface. Using time-resolved infrared reflection absorption spectroscopy, we investigated the reaction of deuterated phenylphosphonic acid (DPPA, C6H5PO3D2) with an atomically defined Co3O4(111) surface in situ during film growth by physical vapor deposition. We show that the binding motif of the phosphonate anchor group changes as a function of coverage. At low coverage, DPPA binds in the form of a chelating tridentate phosphonate, while a transition to a chelating bidentate occurs close to monolayer saturation coverage. However, the coverage-dependent change in the binding motif is not associated with a major change of the molecular orientation, suggesting that the rigid phosphonate linker always maintains the DPPA in a strongly tilted orientation irrespective of the surface coverage.

Hydrothermal syntheses and anion-induced structural transformation of three Cadmium phosphonates

Three cadmium phosphonate coordinated polymers, namely as [Cd5(ptz)3(SO4)2(5H2O)]·6H2O (Cdptz-1), [Cd3(ptz)2(Cl)2(4H2O)]·2H2O (Cdptz-2) and [Cd4(ptz)2(SO4)(Cl)(OH)H2O]·H2O (Cdptz-3) have been hydrothermally synthesized using 4-(1,2,4-triazol-4-yl)phenylphosphonic acid (H2ptz) as ligand. Single crystal X-ray analyses revealed Cdptz-2 as layered structure and Cdptz-1,3 as pillar-layered structures with Cl- or SO42- as bridging anions. Due to the weak bonding between metal and anions, Cdptz-1 and 2 can reversibly convert into each other by simple immersing in the corresponding solution at room temperature. While the transformations between Cdptz-1,2 and Cdptz-3 can only happen under hydrothermal condition. The causes for the transformation involve the metal-ligand bond breaking/formation, replacement of anions and enhancement/decrement of the network dimensionality.

Highly flame‐retardant polyurethane foam based on reactive phosphorus polyol and limonene‐based polyol

ABSTRACTPolyurethane foams are in general flammable and their flammability can be controlled by adding flame‐retardant (FR) materials. Reactive FR have the advantage of making strong bond within the polyurethane chains to provide excellent FR over time without compromising physico‐mechanical properties. Here, phenyl phosphonic acid and propylene oxide‐based reactive FR polyol was synthesized and used along with limonene based polyol for preparation of FR polyurethanes. All the obtained foams showed higher closed cell content (above 96%). By the addition of FR–polyol, the compressive strength of the foams showed 160% increment which could be due to reactive nature of FR–polyol. Moreover, 1.5 wt % of phosphorus (P) content reduced the self‐extinguishing time of the foam from 81 (28% weight loss) to 11.2 s (weight loss of 9.8%). Cone test showed 68.6% reduction in peak heat release rate along with 23.4% reduction in thermal heat release. The change in char structure of carbon after burning was analyzed using Raman spectra which, suggests increment in the graphitic phase of the carbon over increased concentration of phosphorus. It can be concluded from this study that phosphorous based polyol could be blended with bio‐based polyols to prepare highly FR and superior physico‐mechanical rigid polyurethane foams. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46224.

The Effect of Phase Continuity on the Cathodic Delamination Resistance of Polyaniline Based Coatings

Organic coatings based on electrically conducting polyaniline emeraldine salts (ES) and electrically insulating polyvinyl butyral (PVB) are applied to an iron substrate. An investigation is made into how ES phase continuity, and in-coating charge percolation, affect the kinetics and mechanism of corrosion driven cathodic coating delamination. Bilayer coatings are prepared by solution casting continuous ES films onto the substrate, then overcoating with PVB. These are compared with composite coatings of decreased phase continuity, prepared using ES powders dispersed in PVB. Coating delamination is followed using scanning Kelvin probe potentiometry and optical spectrophotometry. At ES coating weights < 0.05 mg.cm−2, delamination rate was inversely proportional to coating weight and slower for bilayer coatings. The same trend was found at higher coating weights for ES doped using camphorsulfonic acid. However, for ES doped with phenylphosphonic acid, bilayer coating delamination rates became independent of ES coating weight > 0.05 mg.cm−2 and were greater than for dispersion coatings. The relationship between cathodic delamination rate and PAni ES continuity is proposed to depend strongly upon the nature and continuity of the interphase formed between the PAni ES coating and iron, and therefore on the dopant anion identity.

Synthesis of phospholipidated β‐cyclodextrin and its application for flame‐retardant poly(lactic acid) with ammonium polyphosphate

ABSTRACTIn this study, phospholipidated β‐cyclodextrin (PCD) was obtained by the condensation between β‐cyclodextrin and phenyl phosphonic acid dichloride, which was characterized by Fourier transform infrared (FTIR) spectra, 1H‐NMR, and thermogravimetric analysis (TGA). The thermal stability and flame retardancy of the poly(lactic acid) (PLA) blends [PLA–ammonium polyphosphate (APP)–PCD] were measured by TGA coupled to FTIR spectroscopy, vertical burning test (UL‐94), limiting oxygen index (LOI), and cone calorimetry tests. The results show that the mass ratio and loading amount of APP and PCD affected the properties of PLA. When the loading of APP and PCD was 30 wt % and the mass ratio of APP to PCD was 5:1, the highest LOI value of 42.6% (that of neat PLA was 19.7%) and a UL‐94 V0 rating were achieved, and the reduction of the total heat release was greater than 80%. Even when the total amount of APP and PCD was decreased to 20 wt % with the same mass ratio, the flame‐retardant PLA still can achieved a UL‐94 V0 rating. The improved performance was explained by the formation of an intumescent, continuous, contact char layer. Moreover, the reaction between APP and PCD contributed to the improvement of the thermal stability of the char residue. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46054.