Phosphonic Acid Anhydride Research Articles

Surface Chemistry of Lead Halide Perovskite Colloidal Nanocrystals.

ConspectusThe surface chemistry of lead halide perovskite nanocrystals (NCs) plays a major role in dictating their colloidal and structural stability as well as governing their optical properties. A deep understanding of the nature of the ligand shell, ligand-NC, and ligand-solvent interactions is therefore of utmost importance. Our recent studies have revealed that such knowledge can be harnessed following a multidisciplinary approach comprising chemical, structural, and spectroscopic analyses coupled with atomistic modeling. We show that specific surface terminations can be produced only by employing flexible and versatile syntheses that enable to work under desired conditions. In this Account, we first describe our studies aimed at synthesizing CsPbBr3 NCs with various surface terminations. These include CsPbBr3 NCs prepared under Br- and oleylamine-rich conditions, which feature a ligand shell composed of alkylammonium-Br species and a photoluminescence quantum yield (PLQY) of ∼90%. On the other hand, taking advantage of the inability of secondary amines to bind to the perovskite NCs surface, we could prepare cuboidal CsPbBr3 NCs bearing a Cs-oleate surface termination and a PLQY of 70% by employing oleic acid and secondary alkylamines. In the quest to identify ligands that can bind more strongly than oleates or primary alkylammonium ions to the surface of NCs already in the synthesis step, we used phosphonic acids as the sole ligands in the CsPbBr3 NCs synthesis, which yielded NCs with a truncated octahedron shape, high PLQY (∼100%), and a PbBr2-terminated surface passivated by hydrogen phosphonates and phosphonic acid anhydride. The surface chemistry and the stability of perovskite NCs were investigated via ad-hoc postsynthesis treatments. We found, for example, that reacting oleylammonium-Br-terminated NCs with stoichiometric amounts of neutral primary alkylamines (or their conjugated acids) led to a partial replacement of oleylammonium ions with new alkylammonium ions (following a deprotonation/protonation mechanism), which resulted in a boost of the PLQY (up to 100%) and of the NCs' colloidal stability. Similar results in terms of optical properties were achieved by treating Cs-oleate-terminated NCs with alkylammonium-carboxylate or quaternary ammonium-Br (namely, didodecyldimethylammonium-Br, DDA-Br) couples. Interestingly, when the native NCs are ligand exchanged with DDA-Br, the ligand shell is then composed of species not bearing any proton. This, in turn, enabled us to study the interaction of such NCs with a variety of ligands under completely aprotic conditions wherein these DDA-Br-capped NCs were basically inert. The only exceptions were carboxylic, phosphonic, and sulfonic acids that were capable of stripping surface DDA-Br couples. As a note, most studies on CsPbBr3 NCs to date have focused primarily on choosing ligands with specific anchoring groups rather than on tuning the length and type of alkyl chains, as this is time-consuming and requires a large number of syntheses. Our recent developments in the computational chemistry of colloidal NCs are expected to provide a pivotal role in this direction since they can be integrated with machine learning models to investigate with greater details the ligand-NC, ligand-ligand, and ligand-solvent interactions and ultimately find optimal candidates through the prediction of surfactant properties using high-throughput data sets.

Novel amides of mycophenolic acid and some heterocyclic derivatives as immunosuppressive agents

The group of 18 new amide derivatives of mycophenolic acid (MPA) and selected heterocyclic amines was synthesised as potential immunosuppressive agents functioning as inosine-5′-monophosphate dehydrogenase (IMPDH) uncompetitive inhibitors. The synthesis of 14 of them employed uronium-type activating system (TBTU/HOBt/DIPEA) while 4 of them concerned phosphonic acid anhydride method (T3P/Py) facilitating amides to be obtained in moderate to excellent yields without the need of phenolic group protection. Most of optimised protocols did not require complicated reaction work-ups, including chromatographic, solvent-consuming methods. The biological activity assay was performed on the T-Jurkat cell line and peripheral mononuclear blood cells (PBMCs) which are both dedicated for antiproliferative activity determination. Each of designed derivatives was characterised by reduced cytotoxicity and benzoxazole analogue (A2) revealed the most promising activity. Subsequently, an observed structure-activity relationship was discussed.

T3P® – A Benign Desulfurating Reagent in the Synthesis of Isothiocyanates

A number of alkyl, aryl and bifunctional isothiocyanates are obtained in moderate to high yields (41–94%) in a two-step, one-pot reaction of the parent primary amines or their salts with carbon disulfide, followed by reaction of the thus formed dithiocarbamates with T3P® (propane phosphonic acid anhydride) as a new and efficient desulfurating agent.

Preparation of proton conducting membranes containing bifunctional titania nanoparticles

Throughout this work, the synthesis and characterization of novel proton conducting nanocomposite membranes including binary and ternary mixtures of sulfated nano-titania (TS), poly(vinyl alcohol) (PVA), and nitrilotri(methyl phosphonic acid) (NMPA) are discussed. The materials were produced by means of two different approaches where in the first, PVA and TS (10–15 nm) were admixed to form a binary system. The second method was the ternary nanocomposite membranes including PVA/TS/NMPA that were prepared at several compositions to get PVA–TS–(NMPA) x . The interaction of functional nano particles and NMPA in the host matrix was explored by FT-IR spectroscopy. The homogeneous distribution of bifunctional nanoparticles in the membrane was confirmed by SEM micrographs. The spectroscopic measurements and water/methanol uptake studies suggested a complexation between PVA and NMPA, which inhibited the leaching of the latter. The thermogravimetry analysis results verified that the presence of TS in the composite membranes suppressed the formation of phosphonic acid anhydrides up to 150 °C. The maximum proton conductivity has been measured for PVA–TS–(NMPA)3 as 0.003 S cm−1 at 150 °C.

A facile and efficient synthesis of tetrahydro-β-carbolines

Abstract This Letter describes a convenient, efficient, and clean synthesis of various tetrahydro-β-carbolines catalyzed by propane phosphonic acid anhydride T3P® under microwave irradiation.

An investigation of proton conductivity of nanocomposite membranes based on sulfated nano-titania and polymer

Abstract The synthesis and physicochemical properties of the nanocomposite polymer electrolyte membranes were investigated throughout this work. The materials were prepared via two different approaches where in the first, a binary system was produced by mixing of poly(1-vinyl 1,2,4-triazole) (P(VTri))/sulfated nanotitania (TS) and poly(vinylphosphonic acid) (P(VPA))/sulfated nanotitania (TS) composites. In the second, ternary nano-composite membranes including P(VTri)/TS/P(VPA) were produced at several compositions to get P(VTri)–TS–P(VPA)x where x designates the molar ratio of the polymer repeating units and sulfated nanotitania ratio. The complex structure of the polymers as well as the interaction of functional nano-particles with the matrix were investigated by FT-IR spectroscopy. TGA results verified that the presence of sulfated nanotitania and P(VTri) in the complex polymer electrolytes suppressed the formation of phosphonic acid anhydrides and thermal stability increased up to approximately 300 °C. The DSC results indicate that the Tg of the materials shifts to lower temperatures as P(VPA) content increases. SEM results showed the homogeneity of the nanocomposite membrane systems. Proton conductivity of the membranes was also measured at the anhydrous state. The conductivity of P(VTri)–TSP(VPA)4 is found to be 0.003 (S cm− 1) at 150 °C. The sulfated nanotitania particles in the composite membranes improved the thermal and mechanical properties and enhanced the proton conductivity.

Nanocomposite polymer electrolyte membranes based on poly (vinylphosphonic acid)/sulfated nano-titania

Proton conductors comprising phosphonic acid units are very promising due to their oxidative stability as well as high proton conductivity. In the present work, the membrane materials were produced by mixing of poly(vinylphosphonic acid) (PVPA) with sulfated nano-titania at various concentrations to get PVPATSx where x designates the molar ratio of the polymer repeating units to sulfate units (varied from 1 to 4). The structure of the nanocomposite polymer membrane is confirmed by FT-IR spectroscopy. The TGA results verify that the presence of sulfated nano-titania in the complex polymer electrolytes suppressed the formation of phosphonic acid anhydrides up to 200°C. DSC results indicate that the Tg of the materials shifts to higher temperatures as sulfated nano-titania content increases. In the anhydrous state, the proton conductivity of PVPATS is found to be 0.03 (Scm−1) at 150°C. Proton conductivity of these membranes are also measured and compared with previous studies. The results suggest that proton conduction is occurred between surface of the nano-titania particles with the aid of sulfonic acid and phosphonic acid units.

Quick Access to Bis(indolyl)methanes: T3P as a Novel Catalyst System

A new catalytic system has been developed in the synthesis of bis(indolyl)methanes using cyclic phosphonic acid anhydride(T3P). Short reaction time, simplicity of isolation, safe catalyst and high yields of product are the features.

Simple synthesis of mixed cellulose acylate phosphonates applying n-propyl phosphonic acid anhydride

Cellulose mixed esters containing alkylphosphonate and carboxylate groups were prepared homogeneously by a new one-pot method using n-propyl phosphonic acid anhydride (T3P®) in LiCl/N-methyl-2-pyrrolidone (NMP). n-Propyl phosphonic acid anhydride acts as both an activating agent for carboxylic acids and phosphonation reagent. Cellulose mixed esters with DSacyl ranging from 1.4 to 1.8, and DSphos up to 0.7 could be prepared. The structure of the cellulose mixed esters was elucidated by FTIR- and NMR spectroscopy, as well as by GPC and solubility tests.

Binding of Phosphonic Acids to CdSe Quantum Dots: A Solution NMR Study

We use 1H and 31P solution nuclear magnetic resonance spectroscopy to analyze the binding of phosphonic acid ligands to wurtzite CdSe quantum dots (CdSe QDs). CdSe QDs synthesized with phosphonic acids as a surfactant have a ligand shell composed of phosphonic acid and phosphonic acid anhydride moieties. Titrations of as-synthesized QDs with excess oleic acid do not induce desorption of phosphonic species, whereas titration of oleic-acid-exchanged QDs with excess phosphonic acid shows that the latter quantitatively replaces the oleic acid with a 1:1 stoichiometry. Both the stoichiometry of the oleic acid/phosponic acid exchange interaction and the ratio between the Cd surface excess and the ligand density indicate that phosponic acids bind as hydrogen phosphonates to the CdSe surface.

Development and characterization of polymer electrolyte membranes based on ionical cross-linked poly(1-vinyl-1,2,4 triazole) and poly(vinylphosphonic acid)

The fabrication, thermal and proton conducting properties of complex polymer electrolytes based on poly(vinylphosphonic acid) (VPA) and poly(1-vinyl-1,2,4-triazole) (PVTri) were investigated throughout this work. The membrane materials were produced by complexation of PVPA with PVTri at various concentrations to get PVTriP(VPA) x where x designates the molar ratio of the polymer repeating units and varied from 0.25 to 4. The complexed structure of the polymers was confirmed by FT-IR spectroscopy. The TGA results verified that the presence of PVTri in the complex polymer electrolytes suppressed the formation of phosphonic acid anhydrides up to 150 °C. The DSC and SEM results demonstrated the homogeneity of the materials. Proton conductivity, activation energy and water/methanol uptake of these membranes were also measured. PVTriP(VPA) 2 showed a proton conductivity of 2.5 × 10 −5 S cm −1 at 180 °C in the anhydrous state. After humidification (RH = 50%), PVTri-P(VPA) 4 and PVTri-P(VPA) 2 showed respective proton conductivities of 0.008 and 0.022 S cm −1 at 100 °C, where the conductivity of the latter is close to Nafion 117 at the same humidity level.

Anhydrous proton-conducting properties of triazole–phosphonic acid copolymers: a combined study with MAS NMR

The synthesis, thermal and proton conducting properties of copolymers based on vinylphosphonic acid (VPA) and 1-vinyl-1,2,4-triazole (VTri) were investigated. The copolymers were synthesized by free-radical copolymerization of the corresponding monomers at several monomer feed ratios to obtain poly(VPA-co-VTri) copolymer electrolytes. The final structures of the copolymers were confirmed by spectroscopic methods. The composition of the low molecular weight copolymers was varied with the feed ratio of the monomers. The presence of triazole units in the copolymers suppresses the formation of phosphonic acid anhydrides up to 150 degrees C, as verified by both (31)P NMR and TGA. The observation of defined glass transition temperatures indicated that the ionic interactions do not prevent segmental relaxations of the polymer chains. In the absence of humidity, the copolymer electrolyte, poly(VPA-co-VTri), S2 (with 33% triazole content) showed proton conductivity of 10(-3) S cm(-1) at 120 degrees C, which is far higher than in imidazole based copolymers. Two different types of hydrogen-bonded protons were detected by (1)H MAS NMR in the solid copolymer systems, due to different arrangements of triazole and phosphonic acid units.

High-Resolution Solid-State NMR Studies of Poly(vinyl phosphonic acid) Proton-Conducting Polymer: Molecular Structure and Proton Dynamics

The structure and the local proton mobility of poly(vinyl phosphonic acid) were studied by solid-state NMR under fast magic-angle spinning. At elevated temperatures, the signature of the hydrogen-bonded P-OH protons is observed in 1H magic-angle spinning (MAS) NMR as a single resonance at 10.5 ppm. Both 1H double-quantum NMR and variable-temperature experiments demonstrate that P-OH protons are mobile and thus able to contribute to proton conductivity. Below room temperature, two different types of hydrogen-bonded P-OH resonances are observed at 10.5 and 15 ppm, and 1H double-quantum NMR demonstrates that these protons are immobile on the NMR time scale. By means of first-principles calculations of a model polymer, we have assigned the additional hydrogen-bonded species at lower temperatures to phosphonic acid anhydride and charged anhydride. Also, in the 31P MAS NMR spectrum, two distinct resonances appear, arising from "normal" phosphonic acid and phosphonic acid anhydride. 31P double-quantum NMR experiments reveal that there is no phase segregation between normal and phosphonic acid anhydride and the condensation reaction occurs randomly throughout the system. The formation of acid anhydride leads to a decrease in proton conductivity through two mechanisms, (1) decrease in the number of charge carriers and (2) blockage of charge transport pathways through immobilization of charge carriers together with a hindered reorientation of the anhydride group. Our results provide strong evidence for these mechanisms by demonstrating that the conductivity is greatly influenced by the presence of phosphonic acid anhydride.

T3P: A Convenient and Useful Reagent in Organic Synthesis

T3P is a highly reactive n-propyl phosphonic acid cyclic anhydride (II, Scheme 1) originally designed as a coupling agent. [1] T3P works both as coupling and as water removal reagent, offering several advantages over traditional reagents, such as high yields and purity, low toxicity, broad functional group tolerance, low epimerization tendency without any additives, and easy work-up (only water-soluble by-products, eliminating the need of chromatographic columns). [1] [2] It can be prepared from the reaction of propyl phosphonic acid (I, Scheme 1) with acetic anhydride at a temperature preferably in the range of 70-110 °C; then the oligomeric phosphonic acid anhydride intermediate is distilled at 0.01-50 mbar and a temperature range of 200-350 °C. The cyclic anhydride II is immediately dissolved in an inert organic solvent. [3] [4]

Mechanistic Study of Precursor Evolution in Colloidal Group II−VI Semiconductor Nanocrystal Synthesis

The molecular mechanism of precursor evolution in the synthesis of colloidal group II-VI semiconductor nanocrystals was studied using 1H, 13C, and 31P NMR spectroscopy and mass spectrometry. Tri-n-butylphosphine chalcogenides (TBPE; E = S, Se, Te) react with an oleic acid complex of cadmium or zinc (M-OA; M = Zn, Cd) in a noncoordinating solvent (octadecene (ODE), n-nonane-d20, or n-decane-d22), affording ME nanocrystals, tri-n-butylphosphine oxide (TBPO), and oleic acid anhydride ((OA)2O). Likewise, the reaction between trialkylphosphine selenide and cadmium n-octadecylphosphonic acid complex (Cd-ODPA) in tri-n-octylphosphine oxide (TOPO) produces CdSe nanocrystals, trialkylphosphine oxide, and anhydrides of n-octadecylphosphonic acid. The disappearance of tri-n-octylphosphine selenide in the presence of Cd-OA and Cd-ODPA can be fit to a single-exponential decay (kobs = (1.30 +/- 0.08) x 10-3 s-1, Cd-ODPA, 260 degrees C, and kobs = (1.51 +/- 0.04) x 10-3 s-1, Cd-OA, 117 degrees C). The reaction approaches completion at 70-80% conversion of TOPSe under anhydrous conditions and 100% conversion in the presence of added water. Activation parameters for the reaction between TBPSe and Cd-OA in n-nonane-d20 were determined from the temperature dependence of the TBPSe decay over the range of 358-400 K (deltaH++ = 62.0 +/- 2.8 kJ.mol-1, deltaS++ = -145 +/- 8 J.mol-1.K-1). A reaction mechanism is proposed where trialkylphsophine chalcogenides deoxygenate the oleic acid or phosphonic acid surfactant to generate trialkylphosphine oxide and oleic or phosphonic acid anhydride products. Results from kinetics experiments suggest that cleavage of the phosphorus chalcogenide double bond (TOP=E) proceeds by the nucleophilic attack of phosphonate or oleate on a (TOP=E)-M complex, generating the initial M-E bond.

Propane phosphonic acid anhydride: a new promoter for the one-pot Biginelli synthesis of 3,4-dihydropyrimidin-2(1 H)-ones

Propane phosphonic acid anhydride has been found to promote the Biginelli synthesis of 3,4-dihydropyrimidin-2(1 H)-ones. The use of this agent is characterized by moderate costs, low toxicity and simple workup conditions.

Synthesis of Alkyl‐ and Arylphosphonic Acid Monoesters by Direct Esterification of Dibasic Phosphonic Acids in the Presence of an Arsonic Acid Catalyst.

Partial hydrolysis of a diester, hydrolysis of the monochloro monoester, or alcoholysis of a phosphonic acid anhydride generally is used to prepare monoesters of alkyl- and arylphosphonic acids. Limited cases have been reported for the esterification of a dibasic phosphonic acid to yield the monoester, and none of these methods are as simple as the analogous method for preparing carboxylic acid esters, in which the carboxylic acid is esterified with an alcohol in the presence of an acid catalyst. Described is a method for preparing monoesters of alkyl- and arylphosphonic acids by direct esterification with an alcohol in the presence of a catalytic amount of phenylarsonic acid. The water formed during the reaction is removed azeotropically. For example, methylphosphonic acid was esterified in good yield to give its isopropyl, butyl, cyclohexyl, bornyl, and octadecyl monoesters. Similarly prepared are the ethyl, butyl, hexyl, and 2-(ethylthio)ethyl monoesters of phenylphosphonic acid, as well as 2-isopropox...

SYNTHESIS OF ALKYL- AND ARYLPHOSPHONIC ACID MONOESTERS BY DIRECT ESTERIFICATION OF DIBASIC PHOSPHONIC ACIDS IN THE PRESENCE OF AN ARSONIC ACID CATALYST

Partial hydrolysis of a diester, hydrolysis of the monochloro monoester, or alcoholysis of a phosphonic acid anhydride generally is used to prepare monoesters of alkyl- and arylphosphonic acids. Limited cases have been reported for the esterification of a dibasic phosphonic acid to yield the monoester, and none of these methods are as simple as the analogous method for preparing carboxylic acid esters, in which the carboxylic acid is esterified with an alcohol in the presence of an acid catalyst. Described is a method for preparing monoesters of alkyl- and arylphosphonic acids by direct esterification with an alcohol in the presence of a catalytic amount of phenylarsonic acid. The water formed during the reaction is removed azeotropically. For example, methylphosphonic acid was esterified in good yield to give its isopropyl, butyl, cyclohexyl, bornyl, and octadecyl monoesters. Similarly prepared are the ethyl, butyl, hexyl, and 2-(ethylthio)ethyl monoesters of phenylphosphonic acid, as well as 2-isopropoxyethyl hydrogen ethylphosphonate and 2-methoxyethyl hydrogen benzylphosphonate.

Propane Phosphonic Acid Anhydride: A Mild Reagent for β-Lactam Synthesis

The use of propane phosphonic acid anhydride (T3P) as an acid activating reagent was demonstrated in the syntheses of cis β-lactams from the reactions of a glycine Dane salt and various imines.

N-Propane Phosphonic Acid Anhydride - A Condensation Reagent

n-Propane phosphonic acid anhydride (PPAA) (3) was first used as a condensation reagent in peptide synthesis in 1980 by H. Wissmann and is steadily gaining importance in organic synthesis, e. g. in the synthesis of polyamides or flame-resistant epoxy resins. The anhydride 3 can be prepared from propane phosphonic dichloride and water or is commercially available in solutions of DMF or of ethyl acetate. Application of PPAA in synthesis does not afford any in water insoluble by-products which may be advantageous in laboratory preparations but is of major significance in technical scale productions. According to toxicological studies PPAA is relatively nontoxic compared to other condensation reagents such as DCC or ethylmethyl phosphonic acid anhydride.