Triphenylphosphine Oxide Research Articles

Hydrogen bonding in triols on the triphenylphosphine oxide platform in crystal and solution: Effect of linker length

The structure of tripodal phosphoryl alkanols [2-HO(CH2)nOC6H4]3P = O (n = 2, 3, 4) have been studied in crystal and solution by X-ray diffraction and FTIR. Linker length in the phosphoryl alkanols has a dramatic effect on their supramolecular structure in crystal and the type of hydrogen bonding in solution. It has been shown that compounds with n = 2 and 4 in crystal form linear and zigzag chains, respectively, while compound with n = 3 produces ribbons united into 2D networks. IR spectral study indicates that solutions of the triols contain monomers with intramolecular simple or bifurcate association of PO and OH groups, linear and cyclic dimers. The concentration of molecules with bifurcate bond decreases upon linker elongation. The studied compounds showed insignificant anticancer activity.

Vacancies substitution induced interfacial dipole formation and defect passivation for highly stable perovskite solar cells

Although an efficient charge transport is essential to high-performance perovskite solar cells (PSCs), the serious charge trapping in perovskite films is still a barrier to improve the efficiency of PSCs. To overcome this issue, we efficiently suppress the charge trapping by using polar compound materials to reduce defects and improve the match of work functions in PSCs. 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) is used to form an interfacial dipole layer and triphenylphosphine oxide (TPPO) is employed to passivate defects. The interfacial dipole layer not only reduces the surface work function of electron transport layers (ETLs), but also substitutes organic/Cs cation vacancies. Oxygen atoms in TPPO molecules fill anion vacancies on perovskite crystal surfaces. As a result, the power conversion efficiency (PCE) of the champion PSCs has been improved to 21.1% from 18.7%. The target PSCs retained 98.3% of its initial PCE after 214 days in dry air condition (relative humidity about 22% at 25 °C) due to the reduced defect density in perovskite.

Molecular engineering of an electron-transport triarylphosphine oxide-triazine conjugate toward high-performance phosphorescent organic light-emitting diodes with remarkable stability

Organic electron-transport materials are an essential component to boost performances and stability of organic light-emitting diodes. We present a robust organic electron-transport compound 3-(6-(3-(4,6-bis(4-biphenylyl)-l,3,5-triazin-2-yl)phenyl)pyridin-2-yl)phenyldiphenylphosphine oxide by facilely coupling the triphenylphosphine oxide moiety to the 2-phenyl-4,6-bis(4-biphenylyl)-1,3,5-triazine unit via a 2,6-pyridinylene linker. It is well soluble in weakly polar solvents and possesses a high Tg of 123 °C with an exceptional Td≈470 °C at 1% weight loss and deep HOMO/LUMO levels of ca. −6.45/-3.06 eV. The phos-phorescent spectrum measured in solid state at 77 K reveals a notable triplet energy of 2.88 eV. n-Doping with 8-hydroxyquinolatolithium (Liq) produces the electron mobility value of 4.66×10−5-3.21×10−4 cm V−1s−1 @(2–5)×10−5 V cm−1. Moreover, the contrasting solubility of the bromo reaction intermediate and the new compound in alcoholic solvents facilitates separation. The characterizations of bottom- and top-emission green phosphorescent OLEDs involving this single Liq-doped electron-transport layer reveal long stability. In particular, the latter provides outstanding performances with 77.4 cd A−1 (corresponding to an EQE of 18.7%) and 86.8 lm W−1@ca. 1000 cd m−2, based on the green emitter bis(2-phenylpyridine)(2-(4-methyl-3-phenylphenyl)pyridine)iridium(III). Moreover, driven by a constant current for ca. 640 h, the initial luminance of 1000 cd m−2 appears almost no decay.

Efficient defect-passivation and charge-transfer with interfacial organophosphorus ligand modification for enhanced performance of perovskite solar cells

Interfacial engineering is an effective method to improve the performance of perovskite solar cells. Nevertheless, it is still challenging to find a material as interfacial layer with the dual function of defect-passivation and efficient charge-transfer. In this work, organophosphorus ligands, trioctylphosphine oxide (TOPO) and triphenylphosphine oxide (TPPO), were used as passivators through antisolvent process for the interfacial modification. Significantly, the organophosphorus ligands can effectively passivate the defects of perovskite crystals through the formation of Pb–O bond between organophosphorus ligand and undercoordinated Pb2+ ion in perovskite. More interestingly, benzene rings with π electron in TPPO facilitate the charge transfer between perovskite and hole-transporting layer, achieving the best power conversion efficiency of 18.29% with negligible hysteresis, as well as excellent long-term stability with remaining nearly 85% of the initial efficiency after 2000 h storage under 50% humidity ambient air. In contrast, uncharged octyl alkanes in TOPO hinder the charge transfer and lead to the accumulation of charges at interface although it is a good passivator in light emitting devices for charge confinement. Our findings shed light on the importance of efficient transfer when defect-passivation is employed in solar cell.

Zwitterionic Ring-Opened Oxyphosphonium Species from the Ph3P-I2 Mediated Reactions of Benzo[d]oxazol-2(3H)-ones with Secondary Amines.

Instead of the expected substituted 2-aminobenzo[d]oxazoles, relatively stable ring-opened oxyphosphonium betaines were isolated for the first time from the Ph3P-I2-mediated reactions of benzo[d]oxazol-2(3H)-ones with acyclic secondary amines. The structure of one of these compounds was unambiguously confirmed by single-crystal X-ray analysis. Thermolysis of the betaines gave rise to 2-dialkylaminobenzoxazoles with concomitant loss of triphenylphosphine oxide, suggesting their possible role as intermediates in an alternative reaction path.

Synthesis and investigation of enhanced luminescence of Ln(III)-complexes containing fluorinated β-diketone and oxygen donor ancillary ligands for efficient advanced displays

2,2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedione (fod) fluorinated β-diketone had been used to prepare a series of Ln3+ (Eu or Tb) ternary complexes with monodentate ancillary ligands such as aqua, urea, triphenylphosphineoxide (TPPO) and pyridine-N-oxide (PNO). Prepared ternary materials Eu(fod)3.(aqua)2 (1), Tb(fod)3.(aqua)2 (2), Eu(fod)3.(urea)2 (3), Tb(fod)3.(urea)2 (4), Eu(fod)3.(TPPO)2 (5), Tb(fod)3.(TPPO)2 (6), Eu(fod)3.(PNO)2 (7), Tb(fod)3.(PNO)2 (8) were illustrated through various structural and photo-physical spectroscopic practices. Emission measurement showed characteristics strong emission in red aa well as green spectral region accredited to the electric dipole 5D0→7F2 and 5D4→7F5 hypersensitive transitions of Eu3+ and Tb3+ ions respectively. An inclusive comparative investigation of enhancement features in the luminescence intensity had been carried out to determine the role of ancillary ligands. Improved luminosity was achieved as auxiliary ligands not only substituted the solvent molecules in coordination sphere but also indirectly sensitize metal ion through transfer of energy to emissive level of respective Ln3+ ion from triplet state of ligand. Decay curve specified uniformity in chemical environment around central metal ion. Efficient red and green light materials could be successfully used for fabricating OLEDs.

Fabrication, flame retardancy and physical properties of phosphorus containing porous organic polymers/epoxy resin composites

Two kinds of phosphorus containing porous organic polymers (PPOPs) were synthesized through the Friedel-Crafts reaction between triphenylphosphine oxide and 4,4′-bis(chloromethyl)-1,1′-biphenyl (PPOP1) or α,α′-dibromo-p-xylene (PPOP2), where PPOPs were applied to improve the flame retardancy and physical properties of epoxy resin (EP). The PPOPs show high thermal stability, poor combustion properties, and large BET specific surface areas. The average pore diameter is 3.7 nm and 3.5 nm for PPOP1 and PPOP2, respectively. Monomers of EP can effectively diffuse into the pores of PPOPs, and PPOP/EP composites were further prepared by in situ polymerization. With only 1 wt% PPOP1 loaded into the composites, Tg values increase from 114 °C to 117 °C, while tensile strength and flexural modulus increase by 32% and 21%, respectively, resulting from the rigid skeleton of PPOPs and the interpenetrating polymer network structure in the composites. The dielectric constant and loss also decrease with the addition of PPOPs into the EP matrix. Cone calorimeter experiments show that PPOPs exert excellent flame retardancy on the EP matrix. In comparison with pure EP, when loading 5 wt% PPOP2, peak heat release rate, total heat release and total smoke production decrease by 26%, 48% and 39%, respectively. The PPOP/EP composites show higher tensile strength, Tg and flame retardancy than the samples prepared by simply blending the same amount of PPOPs into the EP matrix. Our research provides a promising strategy to prepare flame retardant EP composites with high performances.

Samarium complexes with fluorinated β-diketone and heterocyclic Lewis bases as UV light converters

Four new heteroleptic asymmetric fluorinated β-diketone based [Sm(fod)3] adducts with organic ligands of different denticities (monodentate indazole and triphenylphosphine oxide (tppo), bidentate imidazolyl pyridine (impy) and tridentate 2,4,6-tris(2-pyridyl)-s-triazine (tptz)) have been synthesized and characterized in order to examine the suitability of organic co-ligands as a sensitizer for Sm(III) luminescence. The photoluminescence of the complexes is studied in chloroform and solid state. The dominance of the hypersensitive transition 4G5/2 → 6H9/2 reflects the asymmetry around the Sm (III) ion in the present complexes which is supported by the large values of intensity ratio (RSm). The stark splitting in magnetic dipole 4G5/2 → 6H7/2 transition in the cases of eight coordinate [Sm(fod)3(impy)] (3) and [Sm(fod)3(tppo)2] (4) complexes is similar. However, the splitting pattern of 3 and 4 is distinctively different from the nine- [Sm(fod)3(tptz)] (1) and seven-coordinate [Sm(fod)3(indazole)] (2) complexes. The intensity of the hypersensitive transition and stark splitting of magnetic dipole transition changes significantly upon change in the ligand environment around the Sm (III). The bright luminescence from these complexes reflects efficient energy transfer from the selected sensitizers to Sm (III) ion. It is worth mentioning that the lifetime for 4G5/2 → 6H9/2 transition of complex 3 in solid state is 269 μs which is higher than the lifetime of this transition noted for most of the tris(β-diketonate)Sm(III) reported so for. The emission colour from chloroform solution of [Sm(fod)3(tppo)2] (4) changes from parrot green to orange red upon change in excitation wavelengths. Of the selected sensitizers, the impy is most efficient since the emission from its complex is most intense.

Assessment of organophosphate flame retardants in Mediterranean Boops boops and their relationship to anthropization levels and microplastic ingestion

Plastic litter pollution is increasing in the seas and oceans worldwide, raising concern on the potential effects of plasticizer additives on marine fauna. In this study, muscle samples of 30 bogues (Boops boops; Linneaus, 1758) from the North Western Mediterranean Sea were analysed to assess the concentrations of 19 organophosphate flame retardant (OPFR) compounds and to inspect any relationship with microplastic ingestion and relative levels of anthropization. Out of the 19 OPFRs analysed, 6 compounds were detected, being tri-n-butyl phosphate (TNBP), 2-ethylhexyldiphenyl phosphate (EHDPP) and triphenylphosphine oxide (TPPO) the most abundant. As expected, OPFR concentrations were higher in samples collected off the most anthropized area of the city of Barcelona than in those from the Cap de Creus Marine Protected Area, while no significant correlation was detected between OPFR concentrations and microplastic ingestion. The results of this manuscript provide a first evidence of OPFR presence in the muscle of the bogue and identify the coastal area off Barcelona as a possible concentration area for contaminants, further supporting the use of the bogue as an indicator species of plastic pollution in the Mediterranean Sea.

Sorption of aromatic organophosphate flame retardants on thermally and hydrothermally produced biochars

Aromatic organophosphate flame retardant (OPFR) pollutants and biochars are commonly present and continually released into soils due to their increasingly wide applications. In this study, for the first time, the sorption of OPFRs on biochars was investigated. Although triphenyl phosphate (TPhP) and triphenylphosphine oxide (TPPO) have similar molecular structures and sizes, TPhP exhibited much faster and higher sorption than TPPO due to its stronger hydrophobicity, suggesting the dominant role of hydrophobic interactions in TPhP sorption. The π-π electron donor-acceptor (EDA) interactions also contributed to the sorption process, as suggested by the negative correlation between the sorption capacity of the aromatic OPFRs and the aromatic index (H/C atomic ratios) of biochar. Density functional theory calculations further showed that one benzene ring of aromatic OPFRs has no electrons, which may interact with biochar via π-π EDA interactions. The electrostatic attraction between the protonated P = O in OPFRs and the negatively charged biochar was found to occur at pH below 7. This work provides insights into the sorption behaviors and mechanisms of aromatic OPFRs by biochars.

Organophosphate contaminants in North Atlantic fin whales

Pollution of the marine environment by litter composed of plastics is a growing concern. Chemical additives such as organophosphate flame retardants (OPFRs), which are added to plastics to improve their qualities, are in focus because they allegedly cause adverse effects on marine fauna. Here we analyse OPFR levels in the muscle of fin whales because, as a mysticete, this cetacean obtains its food by filter-feeding and is thus highly vulnerable to marine litter. Moreover, the fin whale performs long-range migrations from low-latitude areas in winter to high-latitude areas in summer, a trait that makes it a potentially good large-scale biomonitor of pollution. We also analyse OPFR levels in its main prey, the krill Meganyctiphanes norvegica, to assess transfer through diet. The samples analysed consisted of muscle tissue from 20 fin whales and whole-body homogenates of 10 krill samples, all collected off West Iceland. From the 19 OPFRs analysed, we detected 7 in the fin whale and 5 in the krill samples. Tri-n-butyl phosphate (TNBP), Isopropylated triphenyl phosphate (IPPP) and Triphenylphosphine oxide (TPPO) were the most abundant compounds found in both species. Mean ∑OPFR concentration, expressed on a lipid weight basis, was 985 (SD = 2239) ng g−1 in fin whale muscle, and 949 (SD = 1090) ng g−1 in krill homogenates. These results constitute the first evidence of the presence of OPFRs in the tissues of fin whales. Furthermore, they seem to support the non-significance of bioaccumulation of OPFRs through lifespan and of biomagnification trough the food web.

Distribution, source apportionment and ecological risks of organophosphate esters in surface sediments from the Liao River, Northeast China

A total of 24 surface sediment samples were collected from Liao River, Northeast China. The concentration, spatial distribution, potential source, and ecological risk of 13 organophosphate esters (OPEs) flame retardants and plasticizers were analyzed. The total concentrations of OPEs varied considerably, ranging from 19.7 to 234 ng g−1 dry weight (dw), with the mean concentrations of 64.2 ± 52.2 ng g−1 dw. The OPEs pollution was increasing from upstream to downstream of Liao River. Compared with other sediments of rivers and lakes all over the world, Liao River has been seriously contaminated by OPEs, especially tributyl phosphate (TNBP) and tri-butoxyethyl phosphate (TBOEP). TNBP was the most abundant OPEs, followed by TBOEP and triphenylphosphine oxide. Their mean relative contributions were 26.3%, 12.4% and 11.6%, respectively. Positive matrix factorization indicated that OPEs in sediments from Liao River might be derived from plastic, textile, and polyurethane foam, anti-foam agent, hydraulic fluids, and coatings, indoor release, and chemical process emission. The risk of potential adverse effects of each individually OPEs on aquatic organisms were low (risk quotient less than 0.1). 2-Ethylhexyl diphenyl phosphate was the main substance causing risk.

Development of a Neutral Diketopyrrolopyrrole Phosphine Oxide for the Selective Bioimaging of Mitochondria at the Nanomolar Level

Development of novel bioimaging materials that exhibit organelle specific accumulation continues to be at the forefront of research interests and efforts. Among the various subcellular organelles, mitochondria, which are found in the cytoplasm of eukaryotic cells, are of particular interest in relation to their vital function. To date, most molecular probes that target mitochondria utilise delocalised lipophilic cations such as triphenylphosphonium and pyridinium. However, the use of such charged motifs is known to be detrimental to the working function of the mitochondrial transmembrane potential and there remains a strong case for development of neutral mitochondrial fluorescent probes. Herein, we demonstrate for the first time the exploitation of diketopyrrolopyrrole-based chemistries for the realisation of a neutral fluorescent probe that exhibits organelle specific accumulation within the mitochondria at the nanomolar level. The synthesised probe, which bears a neutral triphenylphosphine oxide moiety, exhibits a large Stokes shift and high fluorescence quantum yield in water, both highly sought-after properties in the development of bioimaging agents. In vitro studies reveal no interference with cell metabolism when tested for the human MCF7 breast cancer cell and nanomolar subcellular organelle colocalisation with commercially available mitochondrial staining agent Mitotracker Red. In light of its novelty, neutral structure and the preferential accumulation at nanomolar concentrations we anticipate this work to be of significant interest for the increasingly larger community devoted to the realisation of neutral mitochondrial selective systems and more widely to those engaged in the rational development of superior organic architectures in the biological field.

Disentangling different modes of mobility for triphenylphosphine oxide adsorbed on alumina.

Triphenylphosphine oxide (TPPO, 1) has been adsorbed on neutral alumina by dry grinding of the components in the absence of a solvent. The adsorption proves translational mobility of 1 on the surface of alumina. Different surface coverages from a densely packed monolayer (99% coverage) to a dilute sub-monolayer (25%) have been produced. The samples have been studied by diverse multinuclear 1H, 13C, and 31P variable temperature solid-state nuclear magnetic resonance (NMR) techniques. The interactions of 1 with the surface are determined by hydrogen bonding of the P=O group to OH groups on the surface. The 31P solid-state NMR spectra prove that even at low temperatures, the molecules of 1 are highly mobile on the surface. Using T1 and T2 relaxation time analyses of the 31P resonance in the solid state at variable temperatures allowed the identification and quantification of two different modes of mobility. Besides the translational mobility that consists of jumps from one hydrogen-bonding OH site on the surface to an adjacent one, a rotational movement around the axis defined by the P=O group of 1 occurs.

Luminescence intensification of terbium(III) ion complexes with dipivaloylmethane (tmhd) and monodentate auxiliary ligands

The synthesis, structural analysis and photophysical properties of terbium with dipivaloylmethane (tmhd) and monodentate auxiliary ligands were reported. Aqua (H2O), urea (H2NCONH2), triphenylphosphine oxide ((C6H5)3PO), pyridine-N-oxide (C5H5NO) and 2-pyridinol-N-oxide (HOC5H5NO) were used as monodentate auxiliary ligands. For structural analysis, various spectroscopic techniques were used such as CHN elemental analysis, PNMR and FTIR. Both excitation and emission spectroscopy were used for probing optical characterization. For metal complexes, by examining the emission wavelength compatible with 5D4 → 7F5 transition, luminescent decay time was also deliberated. A relative investigation of photoluminescent character of synthesized complexes were made as the function of monodentate subsidiary ligands in the enrichment of luminescence intensity formed by Tb(III) ion. The value of CIE color coordinates proposed that complexes exhibited dark green luminescence in visible region. The complexes generating green light in visible region play important role in construction of proficient display and lighting devices.

Lanthanide tri- and tetrathionates and their complexes with triphenylphosphine oxide

Lanthanide tri- and tetrathionate containing species have been prepared in solution by the reaction of potassium tri- and tetrathionate with lanthanide perchlorates. Unstable solid materials from these reactions have been examined by infrared spectroscopy and electrospray mass spectrometry (ESI MS). There was evidence of the formation of S3O62− and S4O62− coordination to lanthanide ions, but it was not possible to produce material suitable for single crystal X-ray studies. The reaction of ethanol solutions from Ln(ClO4)3/K2SnO6 (n = 3,4) with triphenylphosphine oxide yielded crystalline materials which have been characterised by infrared spectroscopy, electrospray mass spectrometry, elemental analysis and single crystal X-ray diffraction. The trithionate complexes [Ln(S3O6)(Ph3PO)4]ClO4·3H2O (Ln = Nd, Tb) have been isolated. The tetrathionate/Ph3PO reaction gave rise to significant disproportionation giving a small quantity of [Nd(S4O6)(Ph3PO)4(H2O)]ClO4, a different isomer of [Nd(S3O6)(Ph3PO)4H2O]ClO4, neodymium sulfate and elemental sulfur. The crystal structures of the two isomers of [Nd(S3O6)(Ph3PO)4H2O]ClO4 and that of [Nd(S4O6)(Ph3PO)4H2O]ClO4 are reported. The structure of [Er(H2O)5(Ph3PO)2].5Ph3PO.3[ClO4], formed during the attempted preparation of erbium trithionate complexes, is also described.

Direct and Scalable Electroreduction of Triphenylphosphine Oxide to Triphenylphosphine

The direct and scalable electroreduction of triphenylphosphine oxide (TPPO)-the stoichiometric byproduct of some of the most common synthetic organic reactions-to triphenylphosphine (TPP) remains an unmet challenge that would dramatically reduce the cost and waste associated with performing desirable reactions that are mediated by TPP on a large scale. This report details an electrochemical methodology for the single-step reduction of TPPO to TPP using an aluminum anode in combination with a supporting electrolyte that continuously regenerates a Lewis acid from the products of anodic oxidation. The resulting Lewis acid activates TPPO for reduction at mild potentials and promotes P-O over P-C bond cleavage to selectively form TPP over other byproducts. Finally, this robust methodology is applied to (i) the reduction of synthetically useful classes of phosphine oxides, (ii) the one-pot recycling of TPPO generated from a Wittig reaction, and (iii) the gram-scale reduction of TPPO at high concentration (1 M) with continuous product extraction and in flow at high current density.

Development of a More Sustainable Appel Reaction

Herein, we report a green, chromatography-free Appel chlorination and bromination in both catalytic and stoichiometric form. Improved sustainability was achieved via the effective replacement of chlorinated solvents with dimethyl carbonate and the use of triphenylphosphine oxide (PPh3O) as a recyclable organocatalyst. The substrate scope of this halogenated solvent-free reaction was shown to be analogous to a contemporary methodology, and removal and recovery of PPh3O from the desired products were effectively demonstrated. Investigations into the catalytic cycle were conducted, and REACT-IR was demonstrated to be an effective method of reaction monitoring in situ. Optimized methodology was applied to the synthesis of 1-bromo-4-(1-bromoethyl)benzene, a key building block employed during the discovery of a GSK fatty acid synthase inhibitor.

Conversion of triphenylphosphine oxide to organophosphorus via selective cleavage of C-P, O-P, and C-H bonds with sodium

For over half a century, thousands of tons of triphenylphosphine oxide Ph3P(O) have been produced every year from the chemical industries as a useless chemical waste. Here we disclose efficient transformations of Ph3P(O) with cheap resource-abundant metallic sodium finely dispersed in paraffin oil. Ph3P(O) can be easily and selectively transformed to three reactive organophosphorus intermediates—sodium diphenylphosphinite, sodium 5H-benzo[b]phosphindol-5-olate and sodium benzo[b]phosphindol-5-ide—that efficiently give the corresponding functional organophosphorus compounds in good yields. These functional organophosphorus compounds are difficult to prepare but highly industrially useful compounds. This may allow Ph3P(O) to be used as a precious starting material for highly valuable phosphorus compounds.

Спектрально-люминесцентные свойства разнолигандных комплексных соединений европия(III) c o-метоксибензойной кислотой и фосфорсодержащими нейтральными лигандами

The spectral and luminescent properties of complex compounds of europium (III) with o-methoxybenzoic acid and island-containing phosphorus-containing neutral ligands of the composition Eu (MOBA) 3 • 3Н2О and Eu (MOBA) 3 • L, where MOBA is o-methoxybenzoic acid, D is studied (hexamethylphosphoric triamide), tppo (triphenylphosphine oxide), Et6pa (hexaethylphosphotriamide). It was found that the excitation energy is transferred to the europium ion both from the levels of o-methoxybenzoic acid and from the levels of phosphorus-containing neutral ligands.The electronic absorption spectra, the luminescence excitation spectra, and the Stark structure of 5D0-7Fj (j = 0-2) electronic transitions in the luminescence spectra of mixed-ligand complex europium (III) complex o-methoxybenzoates are analyzed. Europium (III) methoxybenzoate with triphenylphosphine oxide has the highest luminescence intensity.