Diphenylphosphine Oxide Research Articles

Synthetic and mechanistic studies of the multicomponent reaction of 2‑(phenylethynyl)benzaldehyde, primary amine and diphenylphosphine oxide†

Synthetic and mechanistic studies of the multicomponent reaction of 2‑(phenylethynyl)benzaldehyde, primary amine and diphenylphosphine oxide†

Cu2O-catalyzed cascade phosphinylation/cyclization of 2'-aminochalcones for the synthesis of hemi-indigo derivatives.

A Cu2O-catalyzed cascade phosphinylation/cyclization reaction of 2'-aminochalcones and diphenylphosphine oxides to produce hemi-indigo derivatives has been developed. This strategy facilitates the sequential formation of a C-P bonds and a C-N bond in a single reaction step. Notably, the approach features one-pot operation, an earth-abundant copper catalyst, readily available starting materials, a broad substrate scope and high compatibility with functional groups, providing 33 compounds in acceptable yields.

Carbazole-based artificial light-harvesting system for photocatalytic cross-coupling dehydrogenation reaction.

A carbazole-based artificial light-harvesting system (LHS) was successfully fabricated based on the supramolecular assembly of AIE-enhanced donor (CTD), water-soluble phosphate-pillar[5]arene (WPP5), and eosin Y (ESY) acceptor. The formed WPP5-CTD possessed remarkable AIE emission, featuring an ideal energy donor for light harvesting. After encapsulation of ESY, the energy of WPP5-CTD was efficiently transferred to ESY in WPP5-CTD-ESY, and the antenna effect was 38.5, which was much higher than that of recently reported LHSs. Notably, WPP5-CTD-ESY was successfully utilized as a photocatalyst to realize the cross-coupling dehydrogenation reaction of diphenylphosphine oxide and benzothiazole derivatives, suggesting great potential for aqueous photocatalytic applications of this LHS.

Phosphorus‐containing benzoxazine modified epoxy resin: High flame retardancy, low dielectric, and low water absorption

AbstractA phosphorous‐containing benzoxazine, (3‐(4‐hydroxyphenyl)‐3,4‐dihydro‐2H‐benzo[e][1,3]oxazin‐4‐yl)diphenylphosphine oxide (DPOBH), was synthesized and used as flame retardant and co‐curing agent in the presence of 4,4′‐diaminodiphenylsulfone (DDS) for diglycidyl ether of bisphenol‐A (DGEBA) epoxy resin. The flame retardancy, thermal stability, Tg, dielectric properties, and water absorption properties of epoxy resins (EP) were investigated and compared. The incorporation of DPOBH results in ca. 40%–45% increase of limiting oxygen index (LOI) values. UL‐94 V‐0 rating could be achieved for EP/DPOBH1.2 sample with the LOI value of 35.1%. Compared with EP, ca. 47% decrease of peak heat release rate (PHRR) could be obtained for EP/DPOBH1.2. According to the results of cone calorimetry tests (CCT), DPOBH could play roles in both gas and condensed phases. Moreover, the incorporation of DPOBH could reduce the water absorption rate, dielectric constant, and dielectric loss. All results suggest that DPOBH is a type of flame retardant suitable for EP used in electronic fields.

2-(Hydroxypropan-2-yl)diphenylphosphine oxide (HDPO): A convenient precursor to diphenylphosphine oxide (DPO)

A series of organophosphorus compounds including aryl, alkenyl and alkyl substituted diphenylphosphine oxide derivatives Ph2P(O)R (R = aryl, alkenyl, alkyl), were prepared in high yields by using (2-hydroxypropan-2-yl)diphenylphosphine oxide (HDPO) under the similar reaction conditions referring to that with diphenylphosphine oxide (DPO).

Dual Role of Rapid Transport and Efficient Passivation in Inverted Methylammonium‐Free Perovskite Solar Cells Utilizing a Self‐Assembled Porous Insulating Layer

AbstractIn recent years, the surface modification of perovskite by wide band‐gap insulating materials has been one of the main strategies to achieve efficient and stable perovskite solar cells (PSCs). Unfortunately, a significant hurdle in this approach is the dilemma surrounding the quality of passivation and the transport of charges. Here, this trade‐off is overcome by introducing self‐assembled diphenylphosphinic acid (DPPA) porous layer. Applying highly concentrated DPPA solution on the perovskite surface not only provides excellent passivation of entire surface, but also the excess DPPA will form a self‐assembled porous insulating layer (PIL), which forms random submicron‐sized openings at the interface of the insulating layer for accelerated charge transport. In addition, the energy level of the perovskite surface can be modulated by this insulating material to facilitate carrier transport. As a result, an impressive power conversion efficiency (PCE) over 24% has been achieved in methylammonium‐free p‐i‐n devices with an ultrahigh fill factor (FF) of 84.7%. The unencapsulated devices exhibit excellent thermal and operational stability. This work paves a way for establishment of an effective passivation and facilitated transport simultaneously.

Visible-Light-Induced Three-Component Radical Coupling of Selenocarbamates, Enones, and Allylstannanes with Diphenyl (2,4,6-trimethylbenzoyl)phosphine Oxide

AbstractA blue LED-induced three-component coupling of a carbamoyl radical, cyclic enone, and allylstannane was developed. The use of blue LEDs and diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) as a radical initiator permitted the three-component radical coupling to proceed with a high chemoselectivity. An elucidation of the mechanism revealed a pathway for the formation of a tributyltin radical from TPO and allylstannane. This tandem radical reaction is expected to be applicable in natural-product synthesis.

Novel rich aromatic and phosphorus-containing compound cured epoxy resins toward outstanding comprehensive performances

Epoxy resin (EP) is quite flammable, which limits its application in areas such as coatings and electronic and electrical materials. In this study, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) (or diphenylphosphine oxide (DPO)) 3-cyclohexene-1-formaldehyde (CC) and 4,4’diaminodiphenylmethane (DDM) were selected for the synthesis of two rich aromatic and phosphorus-containing compounds (DOPO-CC and DPO-CC). DOPO-CC and DPO-CC were introduced into epoxy pre-polymers to prepare epoxy thermosets with flame retardancy. When 5 wt% DOPO-CC (P content of 0.50 wt%) or DPO-CC (P content of 0.52 wt%) was added, the LOI values of the epoxy thermosets increased from 25.5% (pure EP) to 33.5% (EP added DOPO-CC) and 31.0% (EP added DPO-CC), respectively, and these epoxy thermosets also achieved the UL-94 V-0 rating. Additionally, cone calorimeter tests showed that the peak heat release rate (PHRR) and total heat release (THR) of epoxy thermoset containing 5 wt% DPO-CC reduced by 42.0% and 39.7% compared to those of pure EP, respectively. By reducing the thermal degradation rate (condensed phase) and combining and quenching free radicals (gaseous phase), the introduction of DOPO-CC or DPO-CC can efficiently improve the flame retardancy of epoxy thermosets. More importantly, the epoxy thermosets containing DOPO-CC or DPO-CC exhibited better mechanical properties than pure EP, which could be proven by the storage modulus and tensile strength. This study provided a new class of rich aromatic and phosphorus-containing compounds that can serve as co-curing agents for epoxy thermosets with outstanding comprehensive performances.

Reaction of diphenylphosphinal formic acid hydrazide with isothiocyanates

A new method was proposed for the preparation of diphenylphosphinylformic acid hydrazide based on the reaction of phosphine oxide and trimethylchlorosilane in the presence of a tertiary amine, followed by interaction with chloroformic acid ester and then hydrazine hydrate. The hydrazide moiety was modified into a thiosemicarbazide moiety by reacting diphenylphosphinylformic acid hydrazide with organic isothiocyanates. It was found that in an aqueous alkaline medium, thiosemicarbazides do not heterocyclize to 1,2,4-triazole-3-thiones, as expected. As a result of the rupture of the P-C bond, diphenylphosphinic acid and a 5-thioxo-1,2,4-triazolidin-3-one were formed.

B-P Coupling: Metal Stabilized Phosphinoborate Complexes.

In an effort to establish B-P coupling reactions without the use of phosphine-borane dehydrocoupling agent, we have developed a new synthetic methodology employing group 8 metal σ-borate complex [{κ3 -H,S,S'-BH2 L2 }Ru{κ3 -H,H,S-BH3 L}] (L=NC5 H4 S), 1. Treatment of 1 with chlorodiphenyl phosphine (PPh2 Cl) yielded 1,5-P,S chelated Ru-dihydridoborate species [PPh2 H{κ3 -H,H,S-BH(OH)L}Ru{κ2 -P,S-(Ph2 P)BH2 L}], 2. The insertion of phosphine moiety (PPh2 ) by the cleavage of 3c-2e σ(Ru… H-B) bonding interaction led to the formation of B-P bond. The κ2 -P,S chelated six-membered ring adopted a boat conformation in complex 2. The heterocycle is made of all different atoms, which is one of the rarest examples of heteroatomic ring systems. Theoretical outcomes demonstrated the electronic insight of B-P coupling and stabilization through transition metal. In order to explore an alternate route of B-P bond formation, we have further explored the reaction of 1 and Ru-bis(dihydridoborate) complex, 5 with secondary phosphine oxide (SPO). Although, thermolysis of 1 with diphenylphosphine oxide yielded analogous σ-borate complex 3, the similar reaction of 5 at room temperature led to the formation of novel phosphinous(III) acid incorporated Ru(σ-borate)(dihydridoborate) complex, 6. In a similar fashion, the reaction of 5 with phosphite ligand generated Ru(σ-borate)(dihydridoborate) complex, 7, which is analogous to 6.

Study on the photoinitiation mechanism of carbazole-based oxime esters (OXEs) as novel photoinitiators for free radical photopolymerization under near UV/visible-light irradiation exposure and the application of 3D printing

In this work, twenty-two oxime esters bearing different functional groups and based on carbazole as the chromophore were designed and synthesized as Type I photoinitiators. Interestingly, all structures mentioned in this work have never been reported before (even for their synthesis). These oxime esters were found to have good light absorption properties in the UV–visible range, and especially at 405 nm which is a reference wavelength in photopolymerization. Noticeably, several structures showed better photoinitiation abilities than the benchmark photoinitiator i.e. diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), evidencing the interest of these structures. In order to investigate the photoinitiation mechanism of the two series of oxime esters differing by the position of the photocleavable groups, electronic absorption spectra were determined by molecular modeling and density functional theory calculations. Photopolymerization abilities of the different oxime esters and release of CO2 during the polymerization experiments were determined by Real-Time Fourier Transformed Infrared (RT-FTIR). Active free radicals were characterized by mean of Electron Spin Resonance Spin Trapping (ESR-ST) experiments. On the basis of these different complementary experiments, chemical mechanisms occurring during photopolymerization could be proposed. Experimental results showed that the decarboxylation reaction occurring subsequent to the photocleavage of oxime esters had a beneficial effect on the photoinitiation ability. Finally, 3D printed objects were successfully obtained by using oxime esters exhibiting the best photoinitiating abilities.

Multifunctional Chiral Five‐Coordinated Manganese(II) Complexes for White LED and X‐Ray Imaging Applications

AbstractIn this study, a pair of chiral manganese(II) complexes is reported based on phosphine oxide, denoted as R/S‐[(L)2MnBr]Br (L = 5,5′‐bis(diphenylphosphine oxide)−4,4′‐bi‐1,3‐benzodioxole). These complexes exhibit distinctive five‐coordinated crystal structures and high stability. In addition, R/S‐[(L)2MnBr]Br display intense red luminescence at room temperature and demonstrate outstanding circularly polarized luminescence property, featuring luminescence dissymmetry factor values of +1.56 × 10−2 and −1.94 × 10−2, respectively. By integrating S‐[(L)2MnBr]Br with commercial phosphors, a white light‐emitting diode is successfully fabricated with a correlated color temperature of 4512 K, achieving a remarkable color rendering index of 96.9. Furthermore, a exceptional scintillation performance is observed in the target compounds and ultimately showcase X‐ray imaging with a spatial resolution of up to 11.9 lp mm−1. This endeavor imparts invaluable insights for the advancement of prospective multifunctional chiral manganese(II)‐based luminescent materials.

Photopolymerization-induced phase separation kinetics explored by intermittent irradiation

In this work, we explore the kinetics of the photopolymerization-induced phase separation (photo-PIPS) process and the interplay of mechanisms controlling the development of the microstructure in a photosensitive resin comprised of pentaerythritol tetraacrylate (PETA) and 2-ethylhexyl methacrylate (2-EHMA) monomers with polypropylene glycol (PPG, Mn = 4000 g/mol) linear polymer additive and diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide (TPO) photoinitiator. We control the kinetics of photopolymerization by interrupting the irradiation at various stages of the process and varying the light intensity. Evolution of the microstructure is monitored by transmittance testing and scanning electron microscopy (SEM) inspection of fractured surfaces that are exposed to methanol for the purpose of removing the phase-separated PPG content. The evolution of the network is monitored by real-time Fourier-transform infrared (FTIR) spectroscopy during irradiation and intermittent probing after the cessation of irradiation. Three mechanisms controlling the evolution of the microstructure are identified: phase separation, photoinitiator consumption, and microstructural refinement. Phase separation begins immediately after the onset of network development and leads to a rapid reduction of transmittance due to the formation of PPG-rich subdomains. Microstructural refinement takes place at later stages leading to a reduction of these subdomains, a gradual increase of the PPG concentration within subdomains and an associated increase of transmittance. TPO consumption takes place during irradiation and accounts, to a smaller extent, for the recovery of the transmittance. Interrupting the irradiation allows generation of materials with various degrees of conversion and sizes of phase-separated subdomains, which provides a new way to control material properties.

Stereolithographic 3D printing: Formulation design based on percolation thresholds

Stereolithograpy (SLA) is an optical photosolidification technology, which can be used to produce 3D printed dosage forms. In the present work, the model drug 4-Aminosalicylic was combined with the photopolymer poly(ethylene glycol) diacrylate (PEGDA), the plasticizer poly(ethylene glycol) (PEG) and the photoinitiator diphenyl(2,4,6- trimethylbenzoyl) phosphine oxide (DPPO) to form a printable resin. The design of a commercial SLA printer was modified to enable printing of different light-curing mixtures in the same tank. This optimisation allowed to evaluate up to 18 different resins by printing in parallel, thus reducing time and costs. Resulting 3D printed drug delivery systems were analysed with respect to mechanical parameters and drug dissolution rate. The principles of percolation theory were applied, for the first time, to provide a mechanistic insight into the impact of varying PEGDA-PEG ratios. It could be demonstrated that a critical point is reached at 18 %v/v of PEGDA, representing the minimum amount needed in the resins to produce solid objects. This critical point was related to the site percolation threshold of PEGDA. Additional critical points were identified related to the percolation thresholds of PEGDA and PEG in the formulation. We conclude that percolation theory is a valuable concept to obtain mechanistic insights into 3D printed systems manufactured by SLA and to define the Design Space of these innovative dosage forms.

A convenient synthesis of β-ketophosphine oxides via Ag-mediated oxidative phosphorylation of α-bromostyrenes

Ag-mediated radical phosphorylation of α-bromostyrenes with diphenylphosphine oxides is described. This approach represents a convenient method for the preparation of β-ketophosphine oxides with moderate to good yields under mild reaction conditions.

Highly luminescent and uniform patterned quantum dot color converters via ligand engineering

Patterned quantum dot color converters (QDCCs) convert blue light to green and red light at the pixel level, thus having potential applications in combination with micro-LED and OLED. Lithography is a promising method to fabricate the QDCCs, however, it is still a challenge to achieve highly luminescent and stable patterned QD-photoresist (PR) thick films. Herein, a strategy is developed to fabricate high-performance patterned QDCCs using the lithography process. Firstly, the QDs are modified by replacing their native hydrophobic ligands to achieve compatibility with PRs. Then, a new ligand, diphenylphosphine oxide (DPPO), is introduced to remedy surface defects of the modified QDs. Lastly, conventional lithography is adopted to fabricate QDCCs with a pattern size of 50 × 10 µm and a thickness of 8 µm. The passivation with DPPO is critical to the luminescent properties of the QD-PR films. The DPPO substantially increases the PLQYs of the PR-compatible QDs and the QD-PR films, achieving a supreme PLQY of 71.7% for the green QD-PR films. The present work might shed light on improving the performance of patterned QDCCs and accelerate their applications in new types of display technology.

Asymmetric Ternary Spiro Phosphine Oxide Hosts for Yellow Thermally Activated Delayed Fluorescence Diodes with External Quantum Efficiency Beyond 30%

AbstractYellow thermally activated delayed fluorescence (TADF) organic light‐emitting diodes (OLEDs) are indispensable for lighting, navigation, caution, and so on; however, their development is far behind those of three‐elementary‐color and white analogs, partially because of the lack of host specificity. In this contribution, spiro[bithoxanthene] (ST) and spiro[thioxanthene‐xanthene] (STX) are used as spiro skeletons to form asymmetric ternary structures through introducing two electron‐donating tert‐butyl carbazole (tBCz) and one electron‐withdrawing diphenyl phosphine oxide (DPPO) groups on different rings. The resulting hosts named STSPOtBCz2 and STXSPOtBCz2 not only inherit the steric hindrance of their spiro skeletons, but also achieve the ambipolar characteristics. Their suitable triplet energy levels (T1) of ≈2.5 eV support efficient energy transfer to a conventional yellow TADF emitter 4CzTPNBu with the T1 of ≈2.2 eV. It is shown that compared to STSPOtBCz2 with a symmetric core, the accumulated asymmetry of the spiro skeleton and the kind, number, and position of substitution groups in STXSPOtBCz2 further suppresses the emission quenching, resulting in the state‐of‐the‐art photoluminescent and electroluminescent quantum efficiencies of 93% and 30.6%, respectively. The maximum power efficiency beyond 90 lm W−1 further demonstrates the great potential of multi‐asymmetric host systems for energy‐saving practical application.

Optimizing photocuring properties of ceramic slurry for 3D printing of ceramic membranes

The utilization of 3D printing for fabricating ceramic membranes has garnered increasing attention in recent years. However, the precise preparation of ceramic slurries tailored for this purpose remains an area requiring more systematic research. This paper delves deeper into the photo-curing characteristics of ceramic slurries characterized by high solid content and low viscosity. Employing a mask-curing experimental system, the study investigates the impact of photoinitiators and additives, such as triethanolamine and tartrazine, on the photo-curing performance. Quantitative analysis is carried out, considering various parameters, including curing depth, curing broadening, broadening depth, critical energy, and curing sensitivity. By incorporating diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), triethanolamine (TEOA), and tartrazine at optimized concentrations of 0.1 wt%, 1.5 wt%, and 1.0 wt% respectively, the broadening depth increases significantly, exceeding 200 μm. This effectively meets the curing depth requirements for 3D printing tasks. Consequently, the printed ceramic green body exhibits excellent shape retention, surface flatness (Ra < 0.9 μm), as well as ample strength and toughness. These characteristics provide a solid foundation for the subsequent preparation of high-performance ceramic membranes.

In vitro cytotoxicity evaluation of organotin(IV) complexes derived from bisphosphoramide ligand: DNA binding and molecular docking studies

Considering the valuable position of organotins and the biotic role of phosphorus compounds in biological processes, in this research work, we investigated and introduced a new class of anticancer candidates based on organotin(IV) complexes derived from bisphosphoramide ligands. Four selected complexes were prepared from the reaction of SnMe2Cl2 (C1), SnBu3Cl (C2), SnPh2Cl2 (C3), and SnPh3Cl (C4) metal salts with piperazine-1,4-diylbis(diphenylphosphine oxide) ligand (LP). The newly synthesized complexes were characterized using spectroscopic techniques. Single crystal of C1 structure was determined by X-ray crystallography. Binding potentials of compounds to DNA were also explored using electron absorption titration and competitive fluorescence quenching techniques, which indicated that complexes and CT-DNA strongly interacted. Cytotoxicity assay of compounds against triple-negative human breast cancer (MDA-MB-231) cells proved that three complexes C2, C3, and C4 had a very considerable impact on the reduced viability of cancer cells and among them, C4 revealed the maximum anticancer activity (IC50 = 0.35 ± 1.18 µg/mL, 0.28 µM) in comparison to reference cisplatin drug (IC50 = 19 µM). Furthermore, the analysis and comparison of the orientations and reactive sites of the compounds using molecular docking simulation, pharmacophore, and NCI studies further confirmed the significant effects of the type and number of aryl and alkyl substituents on the biological activities.

Effect of novel furan‐based ester reactive diluent on structure and properties of UV‐crosslinked acrylated rapeseed oil

AbstractUnsaturated furan‐based ester (UES) was prepared by green electrosynthesis using a single‐cell setup and inexpensive graphite electrodes. The UES was validated as a reactive diluent for a bio‐based acrylated rapeseed oil (ARO). UV‐light photopolymerization of the bio‐based resin was initiated using a diphenyl (2,4,6‐trimethylbenzoyl)phosphine oxide (TPO) radical photoinitiator. The addition of 20 wt% UES to ARO dropped the resin viscosity by 1.6‐fold. Incorporating 5 wt% UES into the ARO resin increased crosslinking density νe from 1.07 to 1.65 mol/m3. Fourier‐transform infrared spectroscopy (FT‐IR) spectra revealed that ARO has been grafted with UES. The UES functional moieties promote the formation of soft mobile dangling chain end segments in the developed macromolecular network. UV‐cured thermoset polymer reveals distinct morphologies in SEM micrographs, indicating notable structural changes with the addition of UES. A total of 5 wt% UES increased tensile strength from 0.49 to 0.55 MPa and storage modulus from 7.9 to 12.0 MPa at room temperature (22 ± 1 °C). The biodegradability in composting conditions was investigated, and up to 28% of the initial mass was lost after 60 days. UES was shown as to be efficient reactive diluent that can successfully replace fossil‐based acrylate monomers in vegetable oil‐based thermoset polymer synthesis.