31P NMR Spectroscopy Research Articles

Phosphorus-nitrogen compounds: Part 66. Syntheses, structural and chiral properties of multiheterocyclic cis and trans bis (benzylspiro-N/N) cyclotriphosphazenes

• The cis and trans benzylspiro(N/N)cyclotriphosphazenes were synthesized. • The spectral analyses of all the phosphazenes were presented. • The absolute configurations of the two compounds were examined by X-ray crystallography. • Chirality of the phosphazenes was interpreted using 31P NMR upon the addition of CSA. • Hirshfeld surface analysis was carried out for two compounds. In the present study, dichloro trans-( 7, 8 and 9 ) and cis-( 10, 11 and 12 ) bis(benzylspiroN/N)cyclo-triphosphazenes were prepared by the reaction of hexachlorocyclotriphosphazene, N 3 P 3 Cl 6 ( HCCP ; trimer) with the corresponding diamines ( 1, 2 and 3 ). The reactions of 7, 9 and 10 with excess pyrrolidine yielded trans-( 13 and 14 ) and cis-( 15 ) geminal-phosphazenes. Cis-derivatives ( 10, 11, 12 and 15 ) are to be in the meso form (RS/SR). Since the two benzyl groups are in the trans position in compounds 7, 8, 9, 13 and 14 , they are only expected to be in the form of a racemic mixture (RR/SS). The space groups of 7 and 13 were found to be P 2 1 /n and P 2 1 /c, respectively. These two space groups are centrosymmetric and both enantiomers must exist in the crystal lattices of the compounds. Since the absolute configurations of enantiomers of 7 and 13 are respectively found as RR and SS by X-ray crystallography, the others must be SS and RR. The chiralities of 7 and 13 were also confirmed using 31 P NMR spectroscopy recorded upon the addition of chiral solvating agent [(S)-(+)-2,2,2-trifluoro-1-(9’-anthryl)ethanol, CSA]. In addition, Hirshfeld surface (HS) analysis indicated van der Waals interactions as leading intermolecular interactions in the crystal structures.

Inhibition of SERCA and PMCA Ca2+-ATPase activities by polyoxotungstates

Plasma membrane calcium ATPases (PMCA) and sarco(endo) reticulum calcium ATPases (SERCA) are key proteins in the maintenance of calcium homeostasis. Herein, we compare for the first time the inhibition of SERCA and PMCA calcium pumps by several polyoxotungstates (POTs), namely by Wells-Dawson phosphotungstate anions [P2W18O62]6- (intact, {P2W18}), [P2W17O61]10- (monolacunary, {P2W17}), [P2W15O56]12- (trilacunary, {P2W15}), [H2P2W12O48]12- (hexalacunary, {P2W12}), [H3P2W15V3O62]6- (trivanadium-substituted, {P2W15V3}) and by Preyssler-type anion [NaP5W30O110]14- ({P5W30}). The speciation in the solutions of tested POTs was investigated by 31P and 51V NMR spectroscopy. The tested POTs inhibited SERCA Ca2+-ATPase activity, whereby the Preyssler POT showed the strongest effect, with an IC50 value of 0.37μM. For {P2W17} and {P2W15V3} higher IC50 values were determined: 0.72 and 0.95μM, respectively. The studied POTs showed to be more potent inhibitors of PMCA Ca2+-ATPase activity, with lower IC50 values for {P2W17}, {P5W30} and {P2W15V3}.

Methoxyl-substituted phosphine ligand properties and a case study of formation adducts to indium(III) bromide by DFT calculations

Triphenylphosphine (PPh 3 ) and its five bulky ligands substituted by different numbers of methoxyl groups at different phenyl ring position (such as TMP, TDP, o -Anis 3 P, p -Anis 3 P and m -Anis 3 P) were studied by DFT calculations and by 31 P NMR spectroscopy. The different basicity and binding ability of these substituted ligands were shown to follow the trend TMP > TDP > o -Anis 3 P > p -Anis 3 P > m -Anis 3 P > PPh 3 . This trend is consistent with both In-P bond lengths and intramolecular interaction energies calculated for six adducts formed between these ligands and InBr 3 . • We have conducted a systematic study of the donor properties of a series of bulky triarylphosphines with methoxyl substituents on the phenyl rings using Gaussian16 DFT calculations and 31 P NMR measurements in solution and in the solid state. • The donation or bonding abilities of a series of methoxyl substituents is demonstrated with the trend TMP > TDP > o -Anis 3 P > p -Anis 3 P > m -Anis 3 P > PPh 3 . Both substitution position and the number of methoxyl groups affected the ligand donation properties. • A case study of six bulky phosphine ligands bonded adducts by DFT confirmed that this ligand bonding trend is accuracy by assessment In-P bond lengths of formed adducts. • This bonding trend was proven by our analysis of three available crystal structures for indium(III) complexes, which confirmed the correlation between electron donation ability and chemical bonding distances. Six bulky triphenylphosphine ligands containing substituted methoxyl groups (tris(2,4,6-trimethoxyphenyl)phosphine (TMP), tris(2,6-dimethoxyphenyl)phosphine (TDP), tris( o -methoxyphenyl)phosphine ( o -Anis 3 P), tris( p -methoxyphenyl)phosphine ( p -Anis 3 P), tris( m -methoxyphenyl)phosphine ( m -Anis 3 P) and triphenylphosphine (PPh 3 )) were studied by DFT (density functional theory) calculations and experimental solution/solid-state 31 P NMR spectroscopy. The basicity and binding ability of these substituted ligands, proven by comparison of structural data with DFT-predicted data, are in the order TMP > TDP > o -Anis 3 P > p -Anis 3 P > m -Anis 3 P > PPh 3 . Molecular structures for InBr 3 with bulky ligands (TMP, TDP, o -Anis 3 P, p -Anis 3 P, m -Anis 3 P and PPh 3 ) were calculated using DFT. P-In bond distances generated from these six optimized molecular structures and the calculated intramolecular interaction energies are in agreement with the ligand properties, with strong donation ability for those with the short bond distance; the In-P bond distance from shortest to longest follows a similar trend as predicted by DFT calculations. DFT calculations for these adducts show that methoxyl substitution to triphenylphosphine (PPh 3 ) ligands contributed to its electron donor ability resulting in lower P-In bond distances with relatively large bond interaction energies.

The effect of the presence of a macromolecular organophosphorus flame retardant, poly(N‐[3‐oxopropylmethylphosphinate]ethyleneimine), on the flammability, thermal stability, and mechanical properties of polyamides

AbstractA macromolecular halogen‐free flame retardant, poly(N‐[3‐oxopropylmethylphosphinate]ethyleneimine) (PN) has been developed. This material contains both phosphorus and nitrogen. A simple and scalable process for chemical synthesis on commercial scale is described. FTIR, 1H and 31P NMR spectroscopy were utilized for characterization. The compound has a glass transition temperature of 82°C and is thermally stable up to 330°C. Samples of polyamide 6 containing 1 to 10 wt% of PN were prepared in a kneader. The flammability of polyamide 6/PN blends was investigated using the UL 94 vertical fire test, limiting oxygen index measurements, cone calorimetry, and the glow wire test. Samples containing loadings of 1 wt% and 10 wt% PN have V‐2 and V‐0 ratings, respectively. Specimen containing polyamide 12/PN blends were prepared by extrusion and injection molding for mechanical characterization.

The importance of intramolecular hydrogen bonds for structural stabilization. [Triphenyl-tetrazolium] [tetraphenyldichalcogenoimidodiphosphinates], [Ph3CN4][Ph2P(X)NP(Y)Ph2

In order to know the capacity of the tetrazolium cation [Ph 3 CN 4 ] + to act as a stabilizing influence in the presence of bulky anions and facilitator to obtain suitable crystals for single-crystal X-ray diffraction studies, four new compounds [Ph 3 CN 4 ] [Ph 2 P(X)NP(Y)Ph 2 ] [X = Y = O ( 1 ); X = Y = S ( 2 ); X = Y = Se ( 3 ); X = S, Y = Se ( 4 )] were synthesized. The compounds were characterized by elemental analysis, IR, FAB + mass spectrometry, 1 H, 13 C, and 31 P NMR spectroscopy, and the corresponding single-crystal X-ray structural determinations were acquired. In the four compounds, the neighboring [Ph 3 CN 4 ] + and [Ph 2 P(X)NP(Y)Ph 2 ] - ions are linked by electrostatic interactions, and thus supramolecular polymer chains are generated. To explain the energetic implications of the structural deformations, the interactions and the stabilizer hydrogen bonds, a study was carried out through the Density Functional Theory (DFT).

Active epoxidation bipyridine-oxodiperoxotungstate catalysts

Herein, we report the preparation of four compounds obtained by the reaction of H3PW12O40/H3PO4/H2O2 with 2,2’-bpy (a-22) or 4,4’-bpy (a-44) and H3PW12O40/H2O2 with 2,2’-bpy (b-22) or 4,4’-bpy (b-44) for the catalytic epoxidation of cyclooctene with H2O2 under monophasic conditions. The anions of the four compounds are composed of oxodiperoxotungstate WO(O2)2 moieties and their overall anionic structures are less condensed than the pristine [PW12O40]3− polyoxometalate (PW12) precursor (Raman and IR spectroscopies). The peroxo anions and bipyridine interact in a way differing from one bpy isomer to the other. Isomer 4,4’-bpy interacts electrostatically with the peroxo species and 2,2’-bpy in a coordinative mode. Compounds synthesized with isomer 2,2’-bpy (a-22 and b-22) are more epoxidation-active than those containing 4,4’-bpy (a-44 and b-44). Compounds a-22 and b-22 share the same structure (PXRD), but a-22 exhibits substantially better catalytic activity. This superior catalytic efficiency is associated to the presence of phosphatooxoperoxotungstates PWn (n = 1; 2; 3; 4) species with high n value (namely PW4 > PW3 >> PW2) (31P NMR and Raman spectroscopies). The PWn species are produced before reaction with bipyridine as a result of the degradation of PW12 with H2O2 which, under the employed conditions, is complete after 30 min. In the aqueous solution, the PWn species are present in different concentrations and coexist in a fast-dynamic equilibrium. Under the operated catalytic conditions, our materials outperform the homogeneous benchmark catalyst of Venturello ((C6H13)4N+)3[PW4O24]3−) which shows poor activity. The most active a-22 and b-22 catalysts are partially dissolved in the liquid medium, but they precipitate as the epoxide builds in the reaction medium, allowing for potential catalyst separation and reuse. It is revealed that H2O2 is required not only to generate epoxidation activity, but to preserve the structure of the catalyst, since without it, the structural damaged appears irreversible.

Development of an efficient downstream process for product separation and catalyst recycling of a homogeneous polyoxometalate catalyst by means of nanofiltration membranes and design of experiments

Extractive coupled oxidative desulfurization (ECODS) is a promising technology for efficient deep desulfurization of fuels with integrated product separation. The main objective of this contribution is the development of an efficient downstream process for the separation and recovery of the molecular HPA-5 (H 8 PV 5 Mo 7 O 40 ) catalyst by means of nanofiltration membranes. We obtained optimized parameter settings for the membrane separation process using a Box, Hunter & Hunter design of experiments leading to higher rejection of catalyst components above 99%. The optimized parameters were successfully applied for recycling experiments in ECODS. In detail, model gasoline consisting of benzothiophene in iso octane could be efficiently desulfurized in six consecutive runs with product separation by the means of nanofiltration between the individual runs. Distinct changes of the catalyst structure were indicated by 51 V NMR and 31 P NMR spectroscopy after the second recycling step due to acidification of the aqueous reaction solution. Based on these results, we predict that a continuous process with a coupled nanofiltration separation could push the ECODS technology to industrially relevant technology readiness levels. Nanofiltration (NF) in an alternative membrane system is used to separate polar oxidation products from an aqueous catalyst solution to prevent chemical deactivation of the catalyst in extractive coupled oxidative desulfurization (ECODS). • Extractive coupled oxidative desulfurization (ECODS) is a promising technology for efficient deep desulfurization of fuels. • Development of an efficient downstream process for the separation and recovery of the molecular catalyst. • Optimized parameter settings for the membrane separation process using a Box, Hunter & Hunter design of experiments.

Novel trans iodo(2-(N-alkylsulfamoyl)phenyl)bis(-triphenylphosphine palladium) complexes: Synthesis, mass spectrometry, X-ray structural description, steric map, near infrared analyses and catalytic activities evaluation

Two novel palladium complexes bearing N -ethylbenzenesulfonamide and N -isopropylbenzenesulfonamide have been prepared. The complexes are fully characterized and their molecular structures determined by X-ray analysis. Intermolecular contacts have been analyzed thanks to Hirshfeld surface and the steric demand determined by the %Buried Volume. The catalytic activity was evaluated in cyclopropanation and ATRP reaction. 2-iodo- N -ethylbenzenesulfonamide and 2-iodo- N -isopropylbenzenesulfonamide are used to prepare two novel palladium(II) complexes ( 4 and 5 ) by oxidative addition starting from Pd(PPh 3 ) 4 . The desired complexes are fully characterized by 1 H, 13 C, 31 P NMR and near infrared spectroscopy. Electron spray ionization mass spectrometry analyses showed identical fragmentation process of the complexes starting by the iodine cleavage. The molecular structures of the complexes 4 and 5 are confirmed by X-ray diffraction analysis. The crystal packing of these complexes are stabilized by the presence of hydrogen bonds established between oxygen and hydrogen atoms of the sulfonamide groups. In addition, Hirshfeld surface mapped over d norm , Shape index and molecular electrostatic potential were used to describe the short interactions and electron reach domains. The analyses of molecular fingerprints reveal similar percentage of H···H (∼67%), H···C/C···H (∼23%), H···I/I···H (∼5%) and H···O/O···H (∼4.5%) contacts in 4 and 5 . The valuation of the percentage of buried volume (%V Bur ) of these ligands shows that the N -ethyl- and N -isopropylbenzenesulfonamide substituents took around 30% share of the palladium coordination sphere. Finally, the catalytic activities of these new palladium complexes are evaluated in cyclopropanation of styrene and in atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). The results showed that trans cyclopropane was obtained as major product independently to the tested catalyst. In polymerization reaction, the catalysts show moderate activity and did not induce a controlled polymerization of MMA.

Crystallization of Nano-Sized Macromolecules by the Example of Hexakis-[4-{(N-Allylimino)methyl}phenoxy]cyclotriphosphazene.

The synthesized compound was characterized by 31P, 13C, and 1H NMR spectroscopy and MALDI-TOF mass spectroscopy. According to DSC data, the compound was initially crystalline, but the crystal structure was defective. The crystals suitable for X-ray diffraction study were prepared by slow precipitation of the compound from a solution by a vapor of another solvent. A study of the single crystal obtained in this way demonstrated that the phosphazene ring has a flattened chair conformation. It was found that the sphere circumscribed around the compound molecule has a diameter of 2.382 nm.

Hexa-substituted cyclotriphosphazene derivatives containing hetero-ring chalcones: Synthesis, in vitro cytotoxic activity and their DNA damage determination

In this study, hetero ring hexasubstituted cyclotriphosphazes were obtained in two steps and these compounds were investigated in terms of in vitro cytotoxicity and genotoxicity. The structural characterizations of the starting compounds 1-4 were defined by FT-IR, elemental analysis, and NMR (1H and 13C) spectroscopy techniques. In addition to these techniques, the 31P NMR spectroscopy technique was also used in the characterization of cyclotriphosphazenes (FSC 1-4). The changes in cell viability at 1, 5, 25, 50, and 100μM concentrations against human ovarian (A2780) and human prostate (PC-3 and LNCaP) cell lines for 24h were determined by the MTT assay method. According to MTT assay results, the inhibitory concentration 50 (IC50/LogIC50) value was calculated in Graphpad Prism 6 program. The comet assay was performed to determine whether the effects of compounds on cell viability were through DNA damage. In the comet assay experiments, the highest concentration of compounds (100μM) was applied to the cells for 24h and tail length (TL), tail intensity (TI), olive tail moment (OTM) parameters were examined. The results showed that the compound 1-4 and FSC 1-4 compounds reduced the cell viability against all cancer cell lines (p<0.05). At the same time, different concentrations of these compounds caused DNA damage in all three cell types (p<0.05). The possible interactions and chemical mechanisms of the synthesized compounds were explained by computational methods with molecular docking. In addition, pharmacological properties of drug candidate molecules have been defined. Experimental and calculated data comply with each other. The study results showed that these compounds have cytotoxic effects against cancer cells and suggested that these effects have occurred through genotoxicity.

Platinum(II)-Metallaclip-Based Theranostics for Cell Imaging and Synergetic Chemotherapy-Photodynamic Therapy.

Supramolecular coordination complexes formed by coordination-induced assembly not only avoid the loss of activity of precursors but also provide an efficient way for controlled release, which can be further used in various fields of biology such as drug delivery, cell imaging, and tumor treatment. In this work, a PtII metallaclip (4) was prepared from 4-[4-(1,2,2-triphenylvinyl)phenyl]pyridine (1), 5,10,15-triphenyl-20-(pyridin-4-yl)porphyrin (2), 90o Pt, and glycol-chain-modified isophthalic acid (3) in an acetone/water mixture through the "coordination-driven self-assembly" method. 31P and 1H NMR spectroscopy and high-resolution mass spectrometry were used to characterize the obtained metallaclip 4. 4 can self-assemble into fluorescent nanostructures in aqueous solution because of the tetraphenylethylene unit and its amphiphilic nature. Importantly, the fluorescent nanoparticles not only can be employed for cell imaging but also can generate singlet oxygen (1O2) under 660 nm laser irradiation and the release of Pt drug in the tumor issue for cancer therapy. The work may provide a new way for scientists to construct functional biomaterials with multiple applications via molecular self-assembly.

Achieving Selectivity for Phosphate over Pyrophosphate in Ethanol with Iron(III)-Based Fluorescent Probes.

Two iron(III)-based molecular receptors employing 1,2-hydroxypyridinone ligands were developed for phosphate recognition and fluorescence sensing via indicator displacement assay (IDA). The tetra- and pentadentate ligands enable anion recognition by the iron(III) center via its remaining one or two open coordination sites. Weak protective coordination of fluorescein at those sites prevents the formation of μ-oxo dimers in aerated solutions. Its rapid and selective displacement by inorganic phosphate results in a 20-fold increase in the fluorescence of the indicator. Both receptors exhibit high affinity for inorganic phosphate and high selectivity over common competing anions, including halides, acetate, carbonate, and, remarkably, pyrophosphate as well as arsenate. Coordination of phosphate to the iron(III) center was confirmed by ATR-IR and 31P NMR spectroscopy.

Phospholipid profiling, cholesterol, and tocopherols: Comparison of sow milk fats from two lactation stages and five breeds

Effects of five different breeds (Landrace × Large White, Landrace, Large White, Duroc and Pietrain) and two lactation stages (colostrum and milk) on phospholipids and their fatty acids compositions, cholesterol, and tocopherols in sow milks (n = 100) were investigated in the present study. Six classes of phospholipids were identified using 31 P NMR spectroscopy, with the total phospholipid levels ranging from 56.84 to 151.02 μmol/100 mL. Sphingomyelin (SM) was the most abundant phospholipids (33.57%–48.00%) in both colostrum and milk. Colostrum contained higher percentages of SM, phosphatidylserine (PS), phosphatidylinositol (PI), and ethanolamine plasmalogen (EPLAS) than those in milk, while milk contained higher percentages of phosphatidylcholine (PC), and phosphatidylethanolamine (PE). C16:0 and C18:0, accounting for more than 80% of the saturated fatty acids of phospholipids in both colostrum and milk, decreased throughout the lactation. The average cholesterol concentration in colostrum was 430.60 mg/100 g fat, which was significantly lower than that in milk (646.44 mg/100 g fat). α-Tocopherol levels in Landrace × Large White breed were 38.35 and 15.91 mg/100 g fat in colostrum and milk, respectively, which were significantly higher than other breeds; while no significant variations in β-, γ-, and δ-tocopherols were noted among different breeds. The results demonstrated that lactation stages and breeds were mainly responsible for the significant differences of phospholipids, cholesterol, and tocopherols, providing a theoretical guidance for the manufacture of commercial formula of piglets.

Tetra-bodipy linked mono-spiro cyclotriphosphazene conjugates: Synthesis, characterization and photophysical properties

• Two novel cyclotriphosphazene compounds bearing four BODIPY units was synthesized. • Precursor BODIPY and mono-spiro compound were characterized by single-crystal XRD. • The novel compounds showed their promise as photosensitizers with remarkable ability. In this work, we report the design, synthesis, and characterization of two novel mono-spiro cyclotriphosphazene conjugates bearing four BODIPY units for the first time. The structures of new compounds were fully characterized by FT-IR, MALDI-TOF Mass analysis, 1 H, and 31 P NMR spectroscopies, and elemental analysis. On the other hand, precursor BODIPYs and mono-spiro compound were characterized by single-crystal X-ray diffraction technique. Photophysical properties including absorption and emission profiles and fluorescence lifetimes were investigated via UV–vis absorption and fluorescence emission spectroscopy techniques. The novel mono-spiro conjugates retain the unique photophysical properties of their precursor BODIPYs showing their promise as photosensitizers with remarkable ability like many other photosensitizers.

Feedstock and catalyst impact on bio-oil production and FCC Co-processing to fuels

NREL's thermochemical biomass conversion research is focused on ex-situ upgrading of biomass fast-pyrolysis (FP) vapors as an efficient route to completely biogenic pyrolysis-based fuel precursors, fuels, and value-added chemicals depending on catalyst and process conditions. A near term pathway being developed uses these liquids for co-processing with petroleum feedstocks to assess biogenic carbon incorporation in hydrocarbon fuel feedstocks for potential refinery use. In this work, the impact of feedstock and catalyst on catalytic fast pyrolysis oil (CFPO) composition was determined with the oils then assessed for biogenic fuel production via FCC (fluidized catalytic cracking) co-processing. Biomass vapors were generated via fast pyrolysis with destabilizing vapor components (char, inorganics, tar aerosols) removed by hot gas filtration to produce clean vapors more responsive to catalytic upgrading. A Davison Circulating Riser (DCR), a petroleum industry standard for fluidized catalytic cracking (FCC) catalyst evaluation, was coupled to a custom pyrolyzer system designed to produce consistent-composition pyrolysis vapors as feed to the DCR. Pyrolysis vapors, derived from pure hardwood and softwood, were upgraded using commercially available modified zeolite-based catalysts to produce CFPOs. These upgraded oils were analyzed via 31 P and 13 C NMR spectroscopy, GCxGC-TOF/MS, carbonyl and ultimate analysis (CHNO), and simulated distillation (SIMDIS) to assess both oil chemistry and distillation behavior as they relate to catalyst and feedstock type for producing fungible hydrocarbon product liquids. These exploratory vapor-phase-upgrading results demonstrated the feasibility of producing refinery-compatible hydrocarbon fuel intermediates entirely from biomass-derived fast-pyrolysis vapors using an industry-accepted DCR system for catalytic upgrading. The FCC co-processing results demonstrated the feasibility of using CFPOs with VGO feeds in FCC refinery operations to produce biogenic carbon containing fuels. • A coupled biomass pyrolyzer/DCR system was used to produce clean, low oxygenate content catalytic fast pyrolysis (CFP) oils. • Feedstock and catalyst type impact on CFP oil composition was determined. • These CFP oils were co-processed with vacuum gas oil in the DCR to produce biogenic carbon containing fuels. • About 80% of the biogenic C became liquid fuel comprising gasoline, jet and diesel, the remainder in tailgas/coke.

Studying Lipophilicity Trends of Phosphorus Compounds by 31P-NMR Spectroscopy: A Powerful Tool for the Design of P-Containing Drugs.

Systematically studying the lipophilicity of phosphorus compounds is of great importance for many chemical and biological fields and particularly for medicinal chemistry. Here, we report on the study of trends in the lipophilicity of a wide set of phosphorus compounds relevant to drug design including phosphates, thiophosphates, phosphonates, thiophosphonates, bis-phosphonates, and phosphine chalcogenides. This was enabled by the development of a straightforward log P determination method for phosphorus compounds based on 31P-NMR spectroscopy. The log P values measured ranged between -3.2 and 3.6, and the trends observed were interpreted using a DFT study of the dipole moments and by H-bond basicity (pKHB) measurements of selected compounds. Clear signal separation in 31P-NMR spectroscopy grants the method high tolerability to impurities. Moreover, the wide range of chemical shifts for the phosphorus nucleus (250 to -250 ppm) enables a direct simultaneous log P determination of phosphorus compound mixtures in a single shake-flask experiment and 31P-NMR analysis.

Reaction of bis(dialkylphosphino)amines R2PNHPR2 (R = i-Pr, t-Bu, Ph) with halogens X2 (X = Cl, Br, I): different solvents – different stories

The bis(dialkylphosphino)amines R2PNHPR2 react with elemental halogens X2 in dichloromethane to produce cationic products of the general form [(R)2P(X)-N-(R)2P(X)]+ (R = i-Pr, Ph, and t-Bu; X = Cl, Br, and I). All of the nine possible products have been isolated and characterized using X-ray diffraction. The dichloro compounds crystallize as [HCl2]− salts, while the dibromo and diiodo products have been isolated as trihalides, [X3]−. A number of these compounds have been shown to react further with methanol to produce salts containing [(R)2P(OCH3)N(R)2P(OCH3)]+ cations, some of which have also been characterized using X-ray crystallography. The conversion of [(Ph)2P(I)-N-(Ph)2P(I)][I3] to [(Ph)2P(OCH3)-N-(Ph)2P(OCH3)][I3] was monitored using 31P NMR spectroscopy that revealed a stepwise reaction of the former compound with methanol. The results are discussed within the context of coupled reactions; this is then used to rationalize a mechanism for the formation of a rare catenated bismuth compound we reported previously. We suggest that the formation of the weak Bi–Bi bonds is offset by a coupled or a connected reaction mechanism , involving an irreversible reaction forming strong P–OR bonds in another of the isolated products.

A green and novel method for the preparation of α-aminophosphonates using eggshell as catalyst. X-ray study

An efficient and eco-friendly green methodology is developed for the synthesis of series of α-aminophosphonate derivatives from diverse aldehydes, anilines and triethyl phosphite by using environmentally benign and cost-effective Eggshells as solid heterogeneous base catalyst. The reaction is conducted by the stepwise one pot condensation through Kabachnick–Fields addition reaction in ethanol at room temperature during 25–30 min. High yield, short reaction time, solvent-free condition, waste to wealth, and optimization with the design of experiment are the major advantages of this method. In addition, this study examines the influence of different solvents, temperature and the amount of catalyst on the yield of the reaction. A single crystal of (2S)- diethyl (phenyl) ((4-fluorophenyl)-aminophosphonate (3g) has been obtained after recrystallization from ethanol/dichloromethane (9/1) and selected for X-ray diffraction study. Compound 3g crystallizes in the monoclinic space group P21/c. The structure of the obtained compounds was confirmed by 1H, 13C, and 31P NMR spectroscopy, IR spectroscopy, as well as elemental analysis.

One-Pot and Catalyst-Free Transformation of N-Protected 1-Amino-1-Ethoxyalkylphosphonates into Bisphosphonic Analogs of Protein and Non-Protein α-Amino Acids.

Herein, we describe the development of one-pot transformation of α-ethoxy derivatives of phosphorus analogs of protein and non-protein α-amino acids into biologically important N-protected 1-aminobisphosphonates. The proposed strategy, based on the three-component reaction of 1-(N-acylamino)-1-ethoxyphosphonates with triphenylphosphonium tetrafluoroborate and triethyl phosphite, facilitates good to excellent yields under mild reaction conditions. The course of the reaction was monitored by 31P NMR spectroscopy, allowing the identification of probable intermediate species, thus making it possible to propose a reaction mechanism. In most cases, there is no need to use a catalyst to provide transformation efficiency, which increases its attractiveness both in economic and ecological terms. Furthermore, we demonstrate that the one-pot procedure can be successfully applied for the synthesis of structurally diverse N-protected bisphosphonic analogs of α-amino acids. As shown, the indirect formation of the corresponding phosphonium salt as a reactive intermediate during the conversion of 1-(N-acylamino)-1-ethoxyphosphonate into a 1-aminobisphosphonate derivative is a crucial component of the developed methodology.

Synthesis and characterization of new spiro cyclotriphosphazene derivatives

In the present study, reactions of spiro-N,N-diisopropylpropane-1,3-diamino-2,2–4,4 tetrachlorocyclotriphosphazatriene (1) with 2,2′-dihydroxybiphenyl (2), and 3-amino-1-propanol (3) have been investigated. Dispiro (4, 6) and trispiro (5) phosphazene derivatives were obtained from these reactions. New spirocyclotriphosphazenes (4–6) were characterized by elemental analysis, 1H, 13C and 31P NMR spectroscopy.