Triphenylphosphine Oxide Research Articles

Drastic Enhancement of Photosensitized Energy Transfer Efficiency of a Eu(III) Complex Driven by Arsenic.

In this study, we focused on arsenic as a new potential motif for the ligand design of high-efficiency, luminous lanthanide complexes. A Eu3+ complex bearing triphenylarsine oxide had a photosensitized energy-transfer efficiency 7.9 times higher than that of a Eu3+ complex bearing triphenylphosphine oxide. This is mainly due to the heavy-atom effect of arsenic, which was supported by evaluating the photoluminescence spectra of their corresponding Gd3+ complexes.

Triphenylphosphine Oxide Removal from Reactions: The Role of Solvent and Temperature.

Here, a large-scale feasible, chromatography-free process to purge triphenylphosphine oxide (TPPO) from the crude product of Mitsunobu and Wittig reactions has been developed. Divergence in physicochemical properties like polarity and solubility of TPPO against the product was utilized to precipitate TPPO directly from the reaction mixture and eliminate by simple filtration on a kilogram scale at a pilot plant with high purity of the product.

FFA3 and TRPM5 Are Involved in the Sodium Propionate‐Induced Anion Secretion in Mouse Proximal Colon

Luminal short-chain fatty acids (SCFA) triggers cholinergic signals for anion secretion in the rodent colonic mucosa, while exact mechanisms are still unclear. Tuft cells, one of luminal chemosensing components in the intestine, expresses choline acetyltransferase (ChAT), transient receptor potential menthol 5 (TRPM5) and free fatty acid receptor 3 (FFA3). We thus examined the roles of TRPM5 and FFA3 in SCFA-induced anion secretion in mouse proximal colon. Short-circuit current (Isc) was measured in the muscle-stripped mouse proximal colonic mucosa mounted in an Ussing chamber. Sodium propionate (NaP, 10 mM, m), atropine (10 µM, s), the selective free fatty acid receptor 3 (FFA3) antagonist AR399519 (1 µM, m or s), or the TRPM5 antagonist triphenylphosphine oxide (TPPO, 1 - 300 µM, m or s) were applied to the mucosal (m) or serosal (s) baths of an Ussing chamber. Luminal NaP transiently increased Isc with atropine-sensitive manner. NaP-induced Isc increase was dose-dependently inhibited by luminal application of TPPO (IC50 0.2 µM) by 76%, while serosal TPPO had higher IC50 (53.5 µM). Luminal AR399519 inhibited NaP-induced Isc increase by 77%, while serosal AR399519 inhibited by 48%. Doublecortin-like kinase 1 (DCLK1)-positive tuft cells were scattered in the epithelium, whereas FFA3 was localized in the surface epithelial cells and in the myenteric nerves. These results suggest that tuft cell TRPM5 and epithelial cell FFA3 are both involved in the NaP-induced anion secretion in mouse proximal colon.

Liquid coordination complexes as a new class of catalysts for the synthesis of highly reactive polyisobutylene

A number of acidic liquid coordination complexes (LCCs) based on phosphorus-containing electron donors such as tri-n-octylphosphine oxide (POct3O), triphenylphosphine oxide (PPh3O) or triphenylphoshine (PPh3), and Lewis acids (AlCl3, FeCl3, TiCl4) have been synthesized and tested as catalysts of cationic polymerization of isobutylene. Among different LCCs studied, POct3O–AlCl3 and POct3O–FeCl3 (χ(MCl3) = 0.60) in combination with bis(2-chloroethyl)ether (CE) and iPr2O, respectively, showed best results in terms of monomer conversion, exo-olefin end group content and polydispersity. POct3O–AlCl3/CE catalytic system afforded highly reactive polyisobutylene (HR PIB) with high exo-olefin end group content (75–90%) and low polydispersity (Đ≤2.0) in high yield (70–90%) at 20 °C and high monomer concentration ([IB] = 5.2 M) in n-hexane, although the number-average molecular weight (Mn = 2.500–3.500 g mol−1) is slightly higher than required for application. POct3O–FeCl3/iPr2O catalytic system showed higher activity and regioselectivity in the cationic polymerization of isobutylene as compared to POct3O–AlCl3/CE giving desired low molecular weight HR PIB (Mn = 1500 g mol−1, Đ = 2.1, Fn(exo) = 91%) in quantitative yield at lower catalyst concentration (22 mM for POct3O–FeCl3 vs. 44 mM for POct3O–AlCl3) at room temperature.

Expected and Unexpected Reactivities of Homoleptic LiNacNac and Heteroleptic NacNacMg(TMP) β-Diketiminates toward Various Small Unsaturated Organic Molecules.

Homoleptic LiNacNac forms simple donor–acceptor complexes with N,N′-dicyclohexylcarbodiimide (CyN=C=NCy), triphenylphosphine oxide (Ph3P=O), and benzophenone (Ph2CO). These crystallographically characterized compounds could be regarded as model intermediates en route to reducing the N=C, P=O, and C=O bonds of unsaturated substrates. Heteroleptic NacNacMg(TMP) intriguingly functions as a TMP nucleophile both with t-BuNCO and t-BuNCS, producing a urea or thiourea derivative respectively attached to Mg, though the NacNac ligand in the former reaction also engages noninnocently with a second t-BuNCO molecule via insertion at the reactive NacNac backbone γ-carbon site.

Cobalt-Catalyzed Hydroformylation under Mild Conditions in the Presence of Phosphine Oxides

In the presence of phosphine oxides, specifically triphenylphosphine oxide (P14), the cobalt-catalyzed hydroformylation of olefins takes place under mild conditions compared to traditional processe...

Hyperbranched Rigid Aromatic Phosphorus‐Containing Flame Retardants for Epoxy Resins

AbstractA rigid aromatic phosphorus‐containing hyperbranched flame retardant structure is synthesized from 10‐(2,5‐dihydroxyphenyl)‐10H‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO‐HQ), tris(4‐hydroxyphenyl)phosphine oxide (THPPO), and 1,4‐terephthaloyl chloride (TPC). The resulting poly‐(DOPO‐HQ/THPPO‐terephthalate) (PDTT) is implemented as a flame retardant into an epoxy resin (EP) at a 10 wt% loading. The effects on EP are compared with those of the monomer DOPO‐HQ and triphenylphosphine oxide (OPPh3) as low molar mass flame retardants. The glass transition temperature, thermal decomposition, flammability (reaction to small flame), and burning behavior of the thermosets are investigated using differential scanning calorimetry, thermogravimetric analysis, pyrolysis combustion flow calorimetry, UL 94‐burning chamber testing, and cone calorimeter measurements. Although P‐contents are low at only 0.6 wt%, the study aims not at attaining V‐0, but at presenting a proof of principle: Epoxy resinswith PDTT show promising fire performance, exhibiting a 25% reduction in total heat evolved (THE), a 30% reduction in peak heat release rate (PHRR) due to flame inhibition (21% reduction in effective heat of combustion (EHC)), and an increase in Tg at the same time. This study indicates that rigid aromatic hyperbranched polymeric structures offer a promising route toward multifunctional flame retardancy.

A Mild One-Pot Reduction of Phosphine(V) Oxides Affording Phosphines(III) and Their Metal Catalysts

The metal-free reduction of a range of phosphine(V) oxides employing oxalyl chloride as an activating agent and hexachlorodisilane as reducing reagent has been achieved under mild reaction conditions. The method was successfully applied to the reduction of industrial waste byproduct triphenylphosphine(V) oxide, closing the phosphorus cycle to cleanly regenerate triphenylphosphine(III). Mechanistic studies and quantum chemical calculations support the attack of the dissociated chloride anion of intermediated phosphonium salt at the silicon of the disilane as the rate-limiting step for deprotection. The exquisite purity of the resultant phosphine(III) ligands after the simple removal of volatiles under reduced pressure circumvents laborious purification prior to metalation and has permitted the facile formation of important transition metal catalysts.

Reductive conversion of phosphoryl P(O) compounds to trivalent organophosphines R3P

By introducing trimethylsilyl chloride (TMSCl), the pentavalent phosphoryl P(V) compounds such as triphenylphosphine oxides, secondary phosphine oxides etc., were readily converted to the corresponding R2P(OTMS) intermediates, that can further react efficiently with an electrophile R’X or with a nucleophile R’Li to produce the corresponding trivalent phosphines R2PR’. Chiral phosphines could also be obtained stereospecifically by this strategy.

Improving the extraction performance of polymer inclusion membranes by cross-linking their polymeric backbone

This study aims at comprehensively investigating the possibility of fabricating cross-linked polymer inclusion membranes (PIMs) using the most common base polymers (i.e., poly(vinyl chloride), cellulose triacetate and poly(vinylidene fluoride-co-hexafluoropropylene)), cross-linking polymers or monomers (i.e., poly(ethylene glycol) dimethylacrylate, poly(ethylene glycol) divinylether and N-ethylmaleimide) and photo-initiators (i.e., 2,2-dimethoxy-2-phenyl acetophenone, triarylsulfonium hexafluorophosphate and triphenylphosphine oxide). The suitability of the photo-initiators for the different cross-linking polymers/monomers in poly(vinyl chloride)-based membranes (without extractants) was assessed for the first time, which was followed by optimizing the cross-linking conditions (i.e., membrane composition and duration of UV-irradiation) for all three base polymers studied. The optimum concentrations of photo-initiator and UV-treatment times were different for the different base polymers used, thus highlighting the importance of this study. Aliquat 336 and di-(2-ethylhexyl)phosphoric acid, as the most frequently used PIM extractants, were added to the compositions of the homogeneous cross-linked membranes produced under optimal conditions and the extraction performance of the newly developed cross-linked PIMs was compared with that of their non-cross-linked counterparts in the extraction of SCN− and Zn2+, respectively. The results showed that all but one of the 13 homogeneous cross-linked PIMs obtained in this study could extract up to 45% more of the corresponding target species than their non-cross-linked counterparts and the remaining one performed similarly to the relevant non-cross-linked PIM. The initial fluxes for the cross-linked PIMs were up to 10 times higher than those of the relevant non-cross-linked membranes and in two cases the fluxes were similar in value. These results demonstrate the potential of cross-linking for enhancing the extraction performance of PIMs.

On the Use of Aqueous Metal-Aqua pKa Values as a Descriptor of Lewis Acidity.

The behavior of Lewis acidic metal ions in multimetallic systems has become a subject of intense interest in recent years. Parametrizing the behavior of these ions in nonaqueous conditions, commonly used in the field, is challenging due to the lack of direct measures of the Lewis acidity of metal ions in polar organic solvents. Here, we report the use of triphenylphosphine oxide (TPPO) as a 31P nuclear magnetic resonance (NMR) probe to quantify the Lewis acidity of a library of metal triflate salts using the Gutmann-Beckett method. Plots of the pKa values of the corresponding metal-aqua species, [M(H2O)m]n+, measured in H2O vs the 31P NMR shifts of TPPO in the presence of these metals in deuterated acetonitrile (d3-MeCN) and deuterated dichloromethane (CD2Cl2), display tightly colinear relationships, suggesting similar behavior for these ions in water, d3-MeCN, and CD2Cl2. This colinearity reinforces the utility of the common approach of using the aqueous pKa values as a descriptor of Lewis acidity, regardless of the solvent used in the immediate experiments, and provides an insight into the usefulness of this descriptor in wide-ranging applications. Titration studies in d3-MeCN suggest a 1:1 binding of TPPO with monovalent ions, greater than 1:1 binding with divalent ions, and formation of multiple species with the highly Lewis acidic trivalent ions. Together, these data suggest that both aqueous pKa values and other single-measurement descriptors, while useful, provide only a snapshot of the influence of Lewis acidity on multimetallic chemical systems.

Efficient dinuclear Pt(ii) complexes based on the triphenylphosphine oxide scaffold for high performance solution-processed OLEDs

The triphenylphosphine oxide group was used to develop efficient dinuclear Pt(ii) complexes, which exhibited impressive electroluminescence performance in solution-processed OLEDs.

Synthesis and Characterization of Eu3+ + 2-thenoyltrifluoroacetone + triphenylphosphine Oxide Ternary Complex

Rare earth europium ion (Eu3+) can emit red characteristic fluorescence under UV excitation and is preferred for the preparation of red phosphors for near-UV white LEDs. In this paper, the effects of solvent, reflux time and preparation method on the preparation of europium ternary complexes were studied with europium ion as the central coordination ion, 2-thenoyltrifluoroacetone as the first ligand and triphenylphosphine oxide as the second ligand. The results showed that the better reaction solvent was anhydrous ethanol and the better reflux time was 8 hours. Both the common synthesis method and the solvothermal method could successfully synthesize the europium ternary complex, and the solvothermal method has a higher yield. The europium ternary complex was characterized by inductively coupled plasma emission spectroscopy, element analysis and infrared spectroscopy, and it was proved that the europium complex could emit a strong characteristic red fluorescence of europium with the structure of Eu(TTA)3(TPPO)2 in 1:3:2 coordination ratio.

The regulatory effect of triphenylphosphine oxide on perovskites for morphological and radiative improvement

The influence of a triphenylphosphine oxide (TPPO) additive on the morphology and emission of FAPbBr3 perovskites is investigated by transient and temperature-dependent emission spectra, which indicates the defect passivation through P=O coordination.

Optical properties and electronic structure of Eu(III) complexes with HMPA and TPPO

Two adducts of Eu(III) tris-hexofluoroacetylacetonate with HMPA (OP(N(CH3)2)3, hexamethylphosphotriamide) and TPPO (OP(C6H5)3, triphenylphosphine oxide) were studied by optical spectroscopy and quantum chemistry (DFT/TD-DFT). The structure of the higher occupied molecular orbitals (MO) of the two adducts determines differences in the position of the excitation band maximum of hfac ligands. According to the calculation data, all excited states are caused by the transition to 3 vacant π4* MOs of hfac ligands. Optical spectra of absorption, excitation and luminescence are obtained and interpreted. The peculiarity of the HOMO-LUMO structure, the low value of the energy gap, and the broadened absorption region of hfac ligands compensate the low absorbance ability of the groups N(CH3)2 in a region of 220–360 nm for the adduct Eu(hfac)3(HMPA)2, reducing the luminescence intensity by only 5–10% relative to the adduct of the Eu(III) complex with TPPO ligands.

Investigations on optical properties of Eu0.5 Sm0.5 (TTA)3 tppo hybrid organic complexes molecularly doped in PMMA and PS matrices.

An attempt has been made to synthesize orange-red light-emitting rare earth-doped polymer matrices Eu0.5 Sm0.5 (TTA)3 tppo (Eu=europium, Sm=samarium, TTA=thenoyltrifluoroacetone, tppo=triphenylphosphine oxide) hybrid organic complex by solution technique. Blended thin films were made by molecularly doping the complex in polymethylmethacrylate (PMMA) and polystyrene (PS) polymers at different weight percentages (5%, 10%). These films were solvated in basic and acidic media to explore the effect of solvent on its luminescence properties. UV-visible absorption spectra of these solvated films portray two peaks corresponding to π→π* and n→π* optical transitions in the range 240-275nm and 370-390nm in basic medium. Energy band gap of these thin films in basic medium was found between 3.16eV to 3.20eV and 3.12eV to 3.22eV in acidic medium. Photoluminescence spectra of all films in dichloromethane showed an intense peak at 614nm, whereas in formic acid, the same were found at 475nm, which fell in the orange-red and blue region of the visible spectrum, respectively. CIE coordinates of these solvated films in various solvents and at different weight percentages revealed tunable orange-red to blue light emission with change in polarity of the solvent. Therefore the synthesized complexes blended in the polymers can be shaped into flexible films for fabrication of organic light-emitting diodes (OLEDs) with consistent results, proving their prospect as colour tunable light emissive materials for OLED devices, lasers, displays, and solid-state lighting.

On the Borate-Catalyzed Electrochemical Reduction of Phosphine Oxide: A Computational Study.

Recently, Nocera and co-workers (J. Am. Chem. Soc. 2018, 140, 13711) demonstrated that triaryl borate Lewis acids facilitate the direct electrochemical reduction of triphenylphosphine oxide (TPPO) to triphenylphosphine (TPP). In the present contribution, we report a quantum chemical study unravelling details of the reaction, which also supports the proposed ECrECi mechanism. Alternative electrochemical routes to TPPO reduction facilitated by other Lewis acids (CH3+), or by photocatalysis at semiconductor surfaces, are also briefly discussed.

Tripodal 1,2,3-Triazole Ligands Based on Triphenylphosphine Oxide. Coordination and Extraction Properties

New tripodal 1,2,3-triazole ligands based on triphenylphosphine oxide platform with different linker lengths have been synthesized, and their structure has been determined by elemental analysis, 1H, 13C, and 31P NMR spectroscopy, mass spectrometry, and vibrational (IR and Raman) spectroscopy. The coordination and extraction properties of the new ligands have been studied in the complexation with uranyl nitrate and extraction of micro amounts of uranium(VI) from aqueous phase to 1,2-dichloroethane.

Synthesis of novel aromatic polyamides containing cardo groups and triphenylphosphine oxide structures by a heterogeneous palladium-catalyzed carbonylation and condensation reaction

New aromatic polyamides containing cardo groups and triphenylphosphine oxide structures were synthesized by a heterogeneous palladium-catalyzed carbonylation and condensation of bis(4-(3-iodophenoxy)phenyl)phenylphosphine oxide (BIPPO), aromatic diamines bearing cardo groups, and carbon monoxide. Polycondensations were carried out in N,N-dimethylacetamide under 1 atm of CO at 120 °C in the presence of a magnetically recyclable heterogeneous palladium catalyst and 1,8-diaza-bicyclo[5,4,0]-7-undecene (DBU) and afforded novel aromatic polyamides with inherent viscosities between 0.72 and 0.76 dL/g. All the polyamides were quite soluble in dipolar aprotic solvents and pyridine and could be converted into transparent, flexible, and tough polyamide films by casting from DMAc solutions. These polymers exhibited high thermal and thermooxidative stability with the glass transition temperatures of 237 °C–256 °C, the temperatures at 5% weight loss of 448 °C–465 °C in air. All the phosphorus-containing polyamides self-extinguished as soon as the flame was removed, and the limited oxygen indices (LOIs) of these polymers were in the range of 39%–44%. The polymer films also showed good mechanical properties and high optical transparency.

Peter H. Huy

Peter H. Huy