Phosphine Groups Research Articles

Combining Experimental Isotherms, Minimalistic Simulations, and a Model to Understand and Predict Chemical Adsorption onto Montmorillonite Clays.

An attractive approach to minimize human and animal exposures to toxic environmental contaminants is the use of safe and effective sorbent materials to sequester them. Montmorillonite clays have been shown to tightly bind diverse toxic chemicals. Due to their promise as sorbents to mitigate chemical exposures, it is important to understand their function and rapidly screen and predict optimal clay–chemical combinations for further testing. We derived adsorption free-energy values for a structurally and physicochemically diverse set of toxic chemicals using experimental adsorption isotherms performed in the current and previous studies. We studied the diverse set of chemicals using minimalistic MD simulations and showed that their interaction energies with calcium montmorillonite clays calculated using simulation snapshots in combination with their net charge and their corresponding solvent’s dielectric constant can be used as inputs to a minimalistic model to predict adsorption free energies in agreement with experiments. Additionally, experiments and computations were used to reveal structural and physicochemical properties associated with chemicals that can be adsorbed to calcium montmorillonite clay. These properties include positively charged groups, phosphine groups, halide-rich moieties, hydrogen bond donor/acceptors, and large, rigid structures. The combined experimental and computational approaches used in this study highlight the importance and potential applicability of analogous methods to study and design novel advanced sorbent systems in the future, broadening their applicability for environmental contaminants.

1,4,7‐Triazacyclononane (tacn) with N,N′‐bridging methylene‐bis(phosphinic acid) group and its complexes

AbstractA bicyclic ligand, 1,4,7‐triazacyclononane 1,4‐bridged with methylene‐bis(phosphinate) and bearing benzyl substituent on the remaining amino group, was synthesized from N‐benzyl‐tacn and CH2(PO2H2)2 by two sequential Mannich‐type reactions in a high yield. Basicity of the macrocycle is high (pK1=12.25). Complexes with CuII and NiII ions show dimeric structures in the solid state. The structures exhibit distorted octahedral environment with two ring amino groups from one molecule and two oxygen atoms of chelating bis(phosphinate) anion from the other molecule in the equatorial plane, and with the apical positions occupied by the remaining macrocycle amino group and by one of the phosphinate oxygen atoms. The metal ions in the dimers are additionally bridged by one phosphinate group. Stability of the CuII complex is more than ten orders of magnitude lower than that of the [Cu(nota)]− complex due to a different number and different nature of the pendant arms, and inappropriate arrangement of donor atoms in the ligand bicyclic structure. Rigidity of the short P−C−P chain of the geminal methylene‐bis(phosphinate) does not allow simultaneous coordination of both phosphinate groups and the ring amines to the same metal ion. The low solubility of NiII and ZnII complexes disabled determination of their stability constants.

Hydrophobic Deep Eutectic Solvents for the Recovery of Bio-Based Chemicals: Solid–Liquid Equilibria and Liquid–Liquid Extraction

The solid–liquid equilibrium (SLE) behavior and liquid–liquid extraction (LLX) abilities of deep eutectic solvents (DESs) containing (a) thymol and L-menthol, and (b) trioctylphosphine oxide (TOPO) and L-menthol were evaluated. The distribution coefficients (KD) were determined for the solutes relevant for two biorefinery cases, including formic acid, levulinic acid, furfural, acetic acid, propionic acid, butyric acid, and L-lactic acid. Overall, for both cases, an increasing KD was observed for both DESs for acids increasing in size and thus hydrophobicity. Furfural, being the most hydrophobic, was seen to extract the highest KD (for DES (a) 14.2 ± 2.2 and (b) 4.1 ± 0.3), and the KD of lactic acid was small, independent of the DESs (DES (a) 0.5 ± 0.07 and DES (b) 0.4 ± 0.05). The KD of the acids for the TOPO and L-menthol DES were in similar ranges as for traditional TOPO-containing composite solvents, while for the thymol/L-menthol DES, in the absence of the Lewis base functionality, a smaller KD was observed. The selectivity of formic acid and levulinic acid separation was different for the two DESs investigated because of the acid–base interaction of the phosphine group. The thymol and L-menthol DES was selective towards levulinic acid (Sij = 9.3 ± 0.10, and the TOPO and L-menthol DES was selective towards FA (Sij = 2.1 ± 0.28).

Pursuit of an Electron Deficient Titanium Nitride.

The nitride salt [(PN)2Ti≡N{μ2-K(OEt2)}]2 (1) (PN- = (N-(2-PiPr2-4-methylphenyl)-2,4,6-Me3C6H2) can be oxidized with two equiv of I2 or four equiv of ClCPh3 to produce the phosphinimide-halide complexes (NPN')(PN)Ti(X) (X- = I (2), Cl (3); NPN' = N-(2-NPiPr2-4-methylphenyl)-2,4,6-Me3C6H22-), respectively. In the case of 2, H2 was found to be one of the other products; whereas, HCPh3 and Gomberg's dimer were observed upon the formation of 3. Independent studies suggest that the oxidation of 1 could imply the formation of the transient nitridyl species [(PN)2Ti(≡N•)] (A), which can either oxidize the proximal phosphine atom to produce the Ti(III) intermediate [(NPN')(PN)Ti] (B) or, alternatively, engage in H atom abstraction to form the parent imido (PN)2Ti≡NH (4). The latter was independently prepared and was found to photochemically convert to the titanium-hydride, (NPN')(PN)Ti(H) (5). Isotopic labeling studies using (PN)2Ti≡ND (4-d1) as well as reactivity studies of 5 with a hydride abstractor demonstrate the presence of the hydride ligand in 5. An alternative route to putative A was observed via a photochemically promoted incomplete reduction of the azide ligand in (PN)2Ti(N3) (6) to 4. This process was accompanied by some formation of 5. Frozen matrix X-band EPR studies of 6, performed under photolytic conditions, were consistent with species B being formed under these reaction conditions, originating from a low barrier N-insertion into the phosphine group in the putative nitridyl species A. Computational studies were also undertaken to discover the mechanism and plausibility of the divergent pathways (via intermediates A and B) in the formation of 2 and 3, and to characterize the bonding and electronic structure of the elusive nitrogen-centered radical in A.

Synthesis, characterization and electrochemistry of [Pd(PP)MeCl] compounds with 1,1′-bis(phosphino)ferrocene ligands

Three new [Pd(κ2-PP)MeCl] (PP = 1,1′-bis(dicyclohexylphosphino)ferrocene (dcpf), 1-diphenylphosphino-1′-ditert-butylphosphinoferrocene (dppdtbpf) or 1,1ʹ-bis(5-methyl-2-furanylphosphino)ferrocene (dfurpf)) compounds were prepared and characterized. The X-ray crystal structure of [Pd(dppdtbpf)MeCl] was obtained which allowed for unambiguous determination of the cis/trans- relationship between the methyl and chloride ligands with respect to the different phosphine groups. The oxidative electrochemistry of the three new compounds as well as that of the reported [Pd(κ2-PP)MeCl] (PP = 1,1′-bis(diphenylphosphino)ferrocene (dppf), or 1,1′-bis(diiso-propylphosphino)ferrocene (dippf)) and [Pd(κ3-dtbpf)Me]Cl (dtbpf = 1,1′- bis(ditert-butylphosphino)ferrocene) was examined. The compounds with the κ2-bis(phosphino)ferrocene ligands react with sodium tetrakis(3,5-bis(trifluoromethyl)phenylborate) to lose a chloride ligand and the catalytic activity of these compounds was investigated for the polymerization of phenylacetylene.

Aerogel based on nanoporous aluminium ferrocenyl diphosphinate metal-organic framework

New porous coordination polymer (PCP) has been synthesized using ferrocene-based ligand bearing phosphinic groups (H2fcdHp = 1,1′-ferrocenediyl-bis(H-phosphinic acid)) and aluminum salt. Al-fcdHp was obtained according to a sol–gel approach followed by supercritical CO2 drying. The N2 adsorption properties of aerogel were investigated and N2 amount adsorbed in the pores of PCP reaches 1400 cm3g−1. The aerogel exhibits high surface area of approximately 671 m2/g and redox activity due to ferrocenyl fragment.

Investigation of iron-ammine and amido complexes within a C3-symmetrical phosphinic amido tripodal ligand.

The primary and secondary coordination spheres can have large regulatory effects on the properties of metal complexes. To examine their influences on the properties of monomeric Fe complexes, the tripodal ligand containing phosphinic amido groups, N,N',N''-[nitrilotris(ethane-2,1-diyl)]tris(P,P-diphenylphosphinic amido) ([poat]3-), was used to prepare [FeII/IIIpoat]-/0 complexes. The FeII complex was four-coordinate with 4 N-atom donors comprising the primary coordination sphere. The FeIII complex was six-coordinate with two additional ligands coming from coordination of O-atom donors on two of the phosphinic amido groups in [poat]3-. In the crystalline phase, each complex was part of a cluster containing potassium ions in which KO[double bond, length as m-dash]P interactions served to connect two metal complexes. The [FeII/IIIpoat]-/0 complexes bound an NH3 molecule to form trigonal bipyramidal structures that also formed three intramolecular hydrogen bonds between the ammine ligand and the O[double bond, length as m-dash]P units of [poat]3-. The relatively negative one-electron redox potential of -1.21 V vs. [FeIII/IICp2]+/0 is attributed to the phosphinic amido group of the [poat]3- ligand. Attempts to form the FeIII-amido complex via deprotonation were not conclusive but isolation of [FeIIIpoat(NHtol)]- using the p-toluidine anion was successful, allowing for the full characterization of this complex.

Effect of solvent in the hydrogenation of acetophenone catalyzed by Pd/S-DVB

A solvent effect was found in the hydrogenation of acetophenone catalyzed by a new Pd/S-DVB catalyst, immobilized on a styrene (S)/divinylbenzene (DVB) copolymer containing phosphinic groups.

Trifluoromethyl substitution enhances photoinduced activity against breast cancer cells but reduces ligand exchange in Ru(ii) complex.

A series of five ruthenium complexes containing triphenyl phosphine groups known to enhance both cellular penetration and photoinduced ligand exchange, cis-[Ru(bpy)2(P(p-R-Ph)3)(CH3CN)]2+, where bpy = 2,2′-bipyridine and P(p-R-Ph)3 represent para-substituted triphenylphosphine ligands with R = –OCH3 (1), –CH3 (2) –H (3), –F (4), and –CF3 (5), were synthesized and characterized. The photolysis of 1–5 in water with visible light (λirr ≥ 395 nm) results in the substitution of the coordinated acetonitrile with a solvent molecule, generating the corresponding aqua complex as the single photoproduct. A 3-fold variation in quantum yield was measured with 400 nm irradiation, Φ400, where 1 is the most efficient with a Φ400 = 0.076(2), and 5 the least photoactive complex, with Φ400 = 0.026(2). This trend is unexpected based on the red-shifted metal-to-ligand charge transfer (MLCT) absorption of 1 as compared to that of 5, but can be correlated to the substituent Hammett para parameters and pKa values of the ancillary phosphine ligands. Complexes 1–5 are not toxic towards the triple negative breast cancer cell line MDA-MB-231 in the dark, but 3 and 5 are >4.2 and >19-fold more cytotoxic upon irradiation with blue light, respectively. A number of experiments point to apoptosis, and not to necrosis or necroptosis, as the mechanism of cell death by 5 upon irradiation. These findings provide a foundation for understanding the role of phosphine ligands on photoinduced ligand substitution and show the enhancement afforded by –CF3 groups on photochemotherapy, which will aid the future design of photocages for photochemotherapeutic drug delivery.

Complexes of cyclen side-bridged with a methylene-bis(phosphinate) group

A macrobicyclic cyclen-based ligand containing a geminal bis(phosphinate) N,N′-bridge was synthesized via a Mannich-type reaction. The other two macrocycle amine groups were modified with two acetate pendants, yielding ligand H4L. The cyclen-bis(phosphinate) intermediate, the ligand salt Na0.5(H5L)(H3.5L)Cl·20H2O and CuII complex Li2[Cu(L)]·4H2O were characterized by single-crystal X-ray diffraction. The ligand protonation constants and the stability constants of H4L complexes with Cu(II) and Zn(II) and lanthanide(III) ions were determined by potentiometry. The ligand protonation constants and the stability constants of H4L complexes with Cu(II) and Zn(II) ions are similar to those of H4dota. Conversely, the stabilities of its Ln(III) complexes are ~ 7–10 orders of magnitude lower than those of H4dota complexes due to steric restrictions of the methylene-bis(phosphinate) side bridge. Therefore, these findings indicate that the ligand H4L is suitable for the complexation of transition metal ions.

The Effect of Complexing Reagents on Flotation of Sulfide Minerals and Cassiterite from Tin-Sulfide Tailings

ABSTRACT Using a combination of UV-spectrophotometry, IR-Furie spectroscopy, analytical scanning electron (LEO 1420VP INCA OXFORD ENERGY 350) and laser (KEYENCE VK-9700) microscopy the effect of complexing reagents DBDTC, TMPPh, TOFA, and IM-50 on adsorption layer on the surface of chalcopyrite, galena, arsenopyrite, and cassiterite was studied. The individual formation character of the adsorption layer on each of the listed minerals was identified and the sizes of thin discrete films of the newly formed reagent phase, the strength of their fixation, and the coverage area of the mineral surface were determined. Kinetic photometry established the effective flocculation of cassiterite slimes by a thermomorphic polymer with a phosphine group TMPPh, which helps to reduce the loss of tin with fine fractions. TOFA is a selective tin collector and has advantages over IM-50 in terms of the fixation contrast on cassiterite and quartz. Tests of the developed reagent modes using a composition of complexing reagents have shown the possibility of obtaining sulfide and tin concentrates that met the requirements of metallurgical processing.

Multifunctional iridium dendrimers containing peripheral carbazole/arylamine unit and/or phosphine oxide group for solution-processed electrophosphorescence

The design and synthesis of four novel iridium (III) complexes, (Cz)2Ir(pic), (TPA)2Ir(pic), (PO-Cz)2Ir(pic) and (PO-TPA)2Ir(pic) carrying a hole-transporting carbazole/arylamine group, and/or an electron-transporting phosphine group, were reported on the base of iridium (III) [bis(4,6-difluorophenyl)pyridinato-N,C2]picolinate (FIrpic). The relationships between structures and characterization of four Ir complexes were shown. A few of phosphorescent organic light emitting diodes (PHOLED) doped with four Ir complexes were fabricated, and device using FIrpic with a 10 wt% doping ratio was also afforded for comparison. The bluish green device with (Cz)2Ir(pic) gave highest efficiencies with a maximum current efficiency (CEmax) of 34.7 cd/A, a maximum power efficiency (PEmax) of 20.5 lm/W and a maximum external quantum efficiency (EQEmax) of 11.8%, respectively. Notably, the efficiency roll-off decreases more slowly for (Cz)2Ir(pic) based device than those for other Ir complexes. The slow efficiency roll-off may be ascribed to simplification of electron injection of transportation for (Cz)2Ir(pic).

Cytotoxicity and Antibacterial Activity of Silver Complexes Bearing Semicarbazones and Triphenylphosphine

AbstractThe present work aimed to evaluate the biological activities of the silver (I) complexes, with the formulae [Ag(L)(PPh3)2]+ and [Ag(L)2]+ (L=(E)‐2‐((E)‐3‐phenylallylidene) hydrazine‐1‐carboxamide – CSC and (2E)‐2‐[(3E)‐4‐phenylbut‐3‐en‐2‐ylidene]‐hydrazinecarboxamide – BSC). Four new silver(I) compounds were synthesized and characterized by NMR 1H, 13C‐{1H}, 31P, IR, and UV‐Vis spectroscopies, molar conductivity, and elemental analysis (CNH). High cytotoxicity was found for all complexes being more active than cisplatin in the tested cell lines. The antibacterial assay demonstrated that the compounds without phosphine groups presented high levels of inhibition (80 %) at 70.4 uM against the Gram‐positive and Gram‐negative bacteria strains. The DNA interactions were investigated by UV‐Vis DNA titration, electrophoresis, and circular dichroism experiments. Data showed that the compounds did not interact with DNA in the tested conditions. However, the compounds have provided important information about the structural features that are needed in order to design new silver (I) complexes with biological activities.

The preparation and mechanism of permanently flame retardancy, antistatic, good toughness and high transparent poly(methyl methacrylate)

AbstractA novel kind of poly(methyl methacrylate) (PMMA) copolymer, P(MMA‐co‐HEMAP), with permanently flame retardancy, antistatic, good toughness and high transparency properties was synthesized through the addition of 2‐hydroxyethyl 2‐methyl‐2‐propenoate phosphated (HEMAP), which was chosen as the flame retardant and the antistatic agent. The included phosphine group is necessary for flame retardancy and acryl phosphate group that could absorb water to realize antistatic property while having good compatibility with methyl methacrylate (MMA). Different from the significantly reduction of transparency happened in traditional modification method, the optical property of the P(MMA‐co‐HEMAP) copolymers keeps almost unchanged comparing to that of neat PMMA in the visible range. And the peak Heat Release Rate (pHRR) and Total Heat Release (THR) of the 30PhrHEMAP were significantly reduced by 40% and 36.2%, respectively, while the Limiting Oxygen Index (LOI) increased from 17.8 to 24.5%. The HEMAP decomposed during the combustion process to form polyphosphoric acid, which promotes dehydration and carbonization of polymer matrix to form a cross‐linking yield char and it would reduce fire spread. Besides, the surface resistance of the 30PhrHEMAP could be reduced down to 1010Ω which could achieve antistatic effect. The hydrophilic groups, acryl phosphate on the surface of copolymer was able to absorb moisture from the air for antistatic effects. Furthermore, the toughness of the copolymers was also greatly improved compared to that of neat PMMA. This research provided a method for preparing PMMA copolymer and the resultant P(MMA‐co‐HEMAP) copolymers can significantly improve the three properties simultaneously for the first time.

Towards the intercalation of Li cations to the Co(II) and Mn(II) ferrocenyl-phosphinic MOFs

A possibility to use the Co(II) and Mn(II) metal-organic frameworks (MOFs) with ferrocenyl-phosphinic ligands for storage of lithium cations is analyzed quantum chemically. Ferrocenyl (Fc) moieties are regarded as the most probable site of Li+ location. The effect of phosphinate group on the Li-Fc interaction energies has been evaluated. Similarly to the case of unsubstituted Fc, the most energetically advantageous position of Li+ for ferrocenyl-phosphinic acid is found near cyclopentadienyl ring. For the binuclear models of MOFs Li+-MOFs interaction energies have been estimated. It is shown that reduced Mn(I) and Co(I) MOFs can accommodate one lithium per one Mn or Co ion without destruction, that opens the perspective of using the MOFs under study as electrode materials in LIBs.

Role of the amine and phosphine groups in oleylamine and trioctylphosphine in the synthesis of copper chalcogenide nanoparticles

The effect of the functional groups of capping agents was investigated in the synthesis of copper selenide, copper sulphide and copper oxide nanoparticles using oleylamine (OLA) and trioctylphosphine (TOP). These capping molecules have demonstrated their ability to act as reducing agents, surfactants, solvents and enhancement of colloidal stabilization. They also offer electron donating abilities from the two group 5A elements, P and N. Nitrogen atom in an amine group possess stronger surface interactions and higher basicity than P atom in the phosphines. Copper chalcogenide nanoparticles were prepared using Hot-injection method and characterized using UV/Vis spectroscopy, TEM and XRD. The optical and structural properties of the yielded nanoparticles showed dependence on the type of capping interactions from the two agents. Nanoparticles synthesized using TOP produced two phases whereas a single phase was observed from OLA as confirmed by XRD. Although TOP and OLA exhibit similar features, but their affinity to metals differs resulting to significant different morphology and crystallinity of the produced nanoparticles. Amine group has higher affinity for protons than phosphine due to the lone pair of electrons it possesses which it easily donates to H+ compared to phosphine. The high proton affinity of oleylamine makes it interact faster than trioctylphosphine. OLA in overall produced larger particle sizes compared to TOP but generated a wider variety of shapes.

Application of a Colorimetric and Near-Infrared Fluorescent Probe in Peroxynitrite Detection and Imaging in Living Cells.

Peroxynitrite (ONOO–) plays a vital role in pathological and physiological processes, and an excessive amount of ONOO– causes various diseases. Developing a specific and sensitive method for the detection of ONOO– in biological systems is significant. Herein, we reported a novel colorimetric and near-infrared fluorescent probe (pyridin-4-ylmethyl (Z)-2-cyano-2-(3-((E)-4-hydroxystyryl)-5,5-dimethylcyclohex-2-en-1-ylidene)acetate diphenyl phosphinate group (AN-DP)) based on isophorone and phosphinate groups for ONOO– detection. The probe displayed excellent selectivity toward ONOO– compared with other relevant analytes. It showed a good linear relationship between the fluorescence intensity at 670 nm and ONOO– concentration (0–10 μM) with a low detection limit (53 nM). Importantly, the probe was a colorimetric and near-infrared fluorescent probe suitable for ONOO– detection. Furthermore, the probe could be used for imaging ONOO– in HepG2 cells.

Synthesis of Norbornene-Based Phosphine-Stabilized Silylium Ions Behaving as Masked Frustrated Lewis Pairs

A novel architecture of phosphine-stabilized silylium ions is described. The peculiar moderate flexible framework allows an efficient donation of the phosphine group toward the electron-deficient s...

Comprehensive investigation of the adsorption of 2-carboxyethylphenylphosphinic acid on cassiterite

ABSTRACT The structure–property relationship and adsorption mechanism of a novel collector for cassiterite, 2-carboxyethylphenylphosphinic acid (CEPPA), were comprehensively investigated and compared with those of styrene phosphonic acid (SPA) by density functional theory (DFT) calculations and flotation tests. The net Mulliken charge and frontier molecular orbital (FMO) theory study results indicated that CEPPA exhibited stronger electron-donating ability and higher chemical reactivity than SPA. The flotation test results demonstrated that CEPPA had stronger collecting ability for cassiterite in a much wider effective pH range than SPA. The adsorption simulation results confirmed that the CEPPA molecule was adsorbed on cassiterite (110) surface by two hydrogen bonds. CEPPA monoanion and dianion were adsorbed on cassiterite (110) surface by a series of O-Sn bonds, and the interactions between the O atoms in CEPPA phosphinic group with the Sn atoms on cassiterite (110) surface were stronger than those between the O atoms in CEPPA carboxyl group with the Sn atoms on cassiterite (110) surface. The formation of the O-Sn bonds was mainly contributed from the 2p orbital of O atoms and 5s and 5p orbitals of Sn atoms. The various adsorption configurations of CEPPA on cassiterite accounted for the better collecting ability of CEPPA for cassiterite than that of SPA. The quantitative analysis results were in good agreement with the qualitative experimental test results in a previous paper.

Enzymatic kinetic resolution of desmethylphosphinothricin indicates that phosphinic group is a bioisostere of carboxyl group

Escherichia coli glutamate decarboxylase (EcGadB), a pyridoxal 5’-phosphate (PLP)-dependent enzyme, is highly specific for L-glutamate and was demonstrated to be effectively immobilised for the production of γ-aminobutyric acid (GABA), its decarboxylation product. Herein we show that EcGadB quantitatively decarboxylates the L-isomer of D,L-2-amino-4-(hydroxyphosphinyl)butyric acid (D,L-Glu-γ-PH), a phosphinic analogue of glutamate containing C-P-H bonds. This yields 3-aminopropylphosphinic acid (GABA-PH), a known GABAB receptor agonist and provides previously unknown D-Glu-γ-PH, allowing us to demonstrate that L-Glu-γ-PH, but not D-Glu-γ-PH, is responsible for D,L-Glu-γ-PH antibacterial activity. Furthermore, using GABase, a preparation of GABA-transaminase and succinic semialdehyde dehydrogenase, we show that GABA-PH is converted to 3-(hydroxyphosphinyl)propionic acid (Succinate-PH). Hence, PLP-dependent and NADP+-dependent enzymes are herein shown to recognise and metabolise phosphinic compounds, leaving unaffected the P-H bond. We therefore suggest that the phosphinic group is a bioisostere of the carboxyl group and the metabolic transformations of phosphinic compounds may offer a ground for prodrug design.