Diphenyliodonium Salt Research Articles

CAIP-Induced ROS Production Contributes to Sustaining Atherosclerotic Process Associated with Helicobacter cinaedi Infection through Macrophages and Endothelial Cells Activation.

Several lines of evidence have linked the intestinal bacterium Helicobacter cinaedi with the pathogenesis of atherosclerosis, identifying the Cinaedi Antigen Inflammatory Protein (CAIP) as a key virulence factor. Oxidative stress and inflammation are crucial in sustaining the atherosclerotic process and oxidized LDL (oxLDL) uptake. Primary human macrophages and endothelial cells were pre-incubated with 10 µM diphenyl iodonium salt (DPI) and stimulated with 20 µg/mL CAIP. Lectin-like oxLDL receptor (LOX-1) expression was evaluated by FACS analysis, reactive oxygen species (ROS) production was measured using the fluorescent probe H2DCF-DA, and cytokine release was quantified by ELISA assay. Foam cells formation was assessed by Oil Red-O staining, and phosphorylation of p38 and ERK1/2 MAP kinases and NF-κB pathway activation were determined by Western blot. This study demonstrated that CAIP triggered LOX-1 over-expression and increased ROS production in both macrophages and endothelial cells. Blocking ROS abrogated LOX-1 expression and reduced LDL uptake and foam cells formation. Additionally, CAIP-mediated pro-inflammatory cytokine release was significantly affected by ROS inhibition. The signaling pathway induced by CAIP-induced oxidative stress led to p38 MAP kinase phosphorylation and NF-κB activation. These findings elucidate the mechanism of action of CAIP, which heightens oxidative stress and contributes to the atherosclerotic process in H. cinaedi-infected patients.

Thienothiophene and biphenyl based conjugated porous polymer as a photocatalyst for visible light induced free radical and cationic polymerization

Over the last few decades, photopolymerization has been the center of great attention owing to a variety of desirable features such as mild reaction conditions, cost efficiency and especially, spatiotemporal controllability. In particular, visible light induced polymerizations have been attracting considerable attention due to the concerns on cost efficiency, light penetration and environment safety. In this work, a crosslinked conjugated polymer, TT-BP, was designed and synthesized by Pd (0) catalyzed Suzuki coupling reaction. It was used as a photocatalyst for visible light induced free radical and cationic polymerizations in the presence of diphenyliodonium salt. The reactions were performed for 8 and 24 h in high yields, for which the photocatalyst TT-PB was used repeatedly for each reaction. The maximum conversion reached to 76 % in free radical polymerization of MMA, while the maximum conversion was obtained in cationic polymerization of IBVE with 82 %. This report on reusable conjugated polymer that have been used as a photocatalyst during free-radical and cationic photopolymerizations may lead to the emergence of a new perspective for photocatalyst and photopolymerization processes.

Thiophene End-Functionalized Oligo-(D,L-Lactide) as a New Electroactive Macromonomer for the "Hairy-Rod" Type Conjugated Polymers Synthesis.

The development of the modern society imposes a fast-growing demand for new advanced functional polymer materials. To this aim, one of the most plausible current methodologies is the end-group functionalization of existing conventional polymers. If the end functional group is able to polymerize, this method enables the synthesis of a molecularly complex, grafted architecture that opens the access to a wider range of material properties, as well as tailoring the special functions required for certain applications. In this context, the present paper reports on α-thienyl-ω-hydroxyl-end-groups functionalized oligo-(D,L-lactide) (Th-PDLLA), which was designed to combine the polymerizability and photophysical properties of thiophene with the biocompatibility and biodegradability of poly-(D,L-lactide). Th-PDLLA was synthesized using the path of "functional initiator" in the ring-opening polymerization (ROP) of (D,L)-lactide, assisted by stannous 2-ethyl hexanoate (Sn(oct)2). The results of NMR and FT-IR spectroscopic methods confirmed the Th-PDLLA's expected structure, while the oligomeric nature of Th-PDLLA, as resulting from the calculations based on 1H-NMR data, is supported by the findings from gel permeation chromatography (GPC) and by the results of the thermal analyses. The behavior of Th-PDLLA in different organic solvents, evaluated by UV-vis and fluorescence spectroscopy, but also by dynamic light scattering (DLS), suggested the presence of colloidal supramolecular structures, underlining the nature of the macromonomer Th-PDLLA as an "shape amphiphile". To test its functionality, the ability of Th-PDLLA to work as a building block for the synthesis of molecular composites was demonstrated by photoinduced oxidative homopolymerization in the presence of diphenyliodonium salt (DPI). The occurrence of a polymerization process, with the formation of a thiophene-conjugated oligomeric main chain grafted with oligomeric PDLLA, was proven, in addition to the visual changes, by the results of GPC, 1H-NMR, FT-IR, UV-vis and fluorescence measurements.

NMR spectroscopy as a unique tool for the quantification of weak interactions between trivalent phosphorus compounds and diphenyliodonium ions

The stabilization and characterisation of weakly coordinated EDA complexes realized using low temperature NMR {1H,19F,31P}.

Oxygen-Demanding Photocontrolled RAFT Polymerization Under Ambient Conditions.

A photocontrolled reversible addition-fragmentation chain transfer (RAFT) process is developed by initiating polymerization through a 1,3-diaminopropane-triethylborane (DAPTB)-diphenyl iodonium salt (Ph2 I+ ) complex (DAPTB/Ph2 I+ ) under ambient temperature and atmospheric conditions. Upon demand, this air-stable DAPTB/Ph2 I+ complex is photolyzed to liberate a reactive triethylborane that consumes atmospheric oxygen and generates ethyl radicals, which initiate and mediate RAFT polymerization. Controlled RAFT polymerization is thus achieved without any prior deoxygenation using a novel RAFT chain transfer agent, BP-FSBC, which contains both benzophenone and sulfonyl fluoride moieties. Furthermore, the kinetics of polymerization reveal that the reaction process is rapid, and well-defined polymers are produced by a 61% conversion of 2-hydroxyethyl acrylate (HEA) within 7 min and 77% conversion of N,N-dimethylacrylamide (DMA) within 10.5 min. The temporal and spatial control of this photopolymerization is also demonstrated by an "on/off" switch of UV irradiation and a painting-on-a-surface approach, respectively. In addition, active chain ends are demonstrated by preparing block copolymers by chain extension and click sulfur(VI)-fluoride exchange postreaction using RAFT-derived macrochain transfer agents.

Directly and Indirectly Acting Photoinitiating Systems for Ring‐Opening Polymerization of ϵ‐Caprolactone

AbstractDirectly and indirectly acting photoinitiating systems for cationic ring opening polymerization (ROP) of ϵ‐caprolactone (ϵ‐CL) by using diphenyl iodonium salt (DPI) in the presence of benzyl alcohol were studied and mechanistic details were evaluated. In the direct system, the polymerization is initiated by a Brønsted acid formed upon UV irradiation of DPI. Polymerizations by indirectly acting photoinitiating systems proceeding via electron transfer reactions of photochemically formed electron donor radicals or excited states of polynuclear aromatic compounds with DPI were investigated. It was demonstrated that polymerizations proceed in a controlled manner by an activated monomer (AM) mechanism. Applicability of the photoinitiation to the other lactone monomers was validated on the example of δ‐ valerolactone (δ‐VL).

Mussel-Inspired Coatings by Photoinduced Electron-Transfer Reactions: Photopolymerization of Dopamine under UV, Visible, and Daylight under Oxygen-Free Conditions

Photoinduced electron-transfer (PET) reactions represent a powerful methodology with widespread applications in the fields of organic and synthetic polymer chemistry. Within this literature, among the various surface coating methods, marine mussel-inspired adhesive bonding by polydopamine (PDA) coatings has attracted great interest. Although various procedures for PDA synthesis have been reported, they exhibit some limitations, such as requirement of acidic or basic conditions or strong oxidants. To address these issues, here we report a simple PET protocol for PDA production under UV, visible, and daylight irradiation using diphenyliodonium salt in the presence and absence of sensitizers. This new methodology provides future directions for surface coatings and bio-functionalization.

Visible Light Induced Step-Growth Polymerization by Substitution Reactions.

A new visible light induced step-growth polymerization of dibromoxylene, and diols using dimanganese decacarbonyl and diphenyliodonium salt is described. The polymerization is suggested to proceed by substitution reaction between dixylenium cations formed upon visible light irradiation in the presence of dimanganese decacarbonyl and diphenyl iodonium salt. For the described substitution reaction with diols as nucleophilic component, the scope of the process is studied. Furthermore, the presence of halide groups at chain ends of the resulting polymers provided the possibility of initiating subsequent free radical and free radical promoted cationic resulting in the formation of polyether-based block copolymers.

Quinoline Schiff-base ligands as long-wavelength photosensitizers for diphenyliodonium salt

This study describes the use of quinoline Schiff-base ligands as photosensitizers for diphenyliodonium salt using long-wavelength UV light. 4-Bromo-2-((quinolin-8-ylimino)methyl)phenol (BQIP) and 2-methoxy-6-((quinolin-8-ylimino)methyl)phenol (MQIP) were synthesized and characterized by 1H NMR, 13C NMR, FT-IR, UV–vis and fluorescence measurements. The cationic polymerization of cyclohexene oxide monomer was initiated at room temperature upon LED exposure (395−480 nm) in the presence of BQIP/MQIP and diphenyliodonium hexafluorophosphate (DPI+PF6−). Free energy change (ΔGS) calculations revealed that electron transfer from singlet excited states of the Schiff-bases to DPI+PF6− is thermodynamically favorable.

Photochemical Study of a New Bimolecular Photoinitiating System for Vat Photopolymerization 3D Printing Techniques under Visible Light

In this work, we presented a new bimolecular photoinitiating system based on 2-amino-4,6-diphenylpyridine-3-carbonitrile derivatives as visible photosensitizers of diphenyliodonium salt. Real-time FTIR and photo-DSC photopolymerization experiments with a cycloaliphatic epoxide and vinyl monomers showed surprisingly good reactivity of the bimolecular photoinitiating systems under UV-A, as well as under visible light sources. Steady-state photolysis, fluorescence experiments, theoretical calculations of molecular orbitals, and electrochemical analysis demonstrated photo-redox behavior as well as the ability to form initiating species via photo-reduction or photo-oxidation pathways, respectively. Therefore, the 2-amino-4,6-diphenylpyridine-3-carbonitrile derivatives were also investigated as a type II free-radical photoinitiator with amine. It was confirmed that the 2-amino-4,6-diphenylpyridine-3-carbonitrile derivatives, in combination with different types of additives, e.g., amine as a co-initiator or the presence of onium salt, can act as bimolecular photoinitiating systems for cationic, free-radical, and thiol-ene photopolymerization processes by hydrogen abstraction and/or electron transfer reactions stimulated by either near-UV or visible light irradiation. Finally, the 2-amino-4,6-diphenylpyridine-3-carbonitrile derivatives were selected for 3D printing rapid prototyping experiments. Test objects were successfully printed using purely cationic photosensitive resin, created on a 3D printer with a visible LED light source.

New versatile bimolecular photoinitiating systems based on amino-m-terphenyl derivatives for cationic, free-radical and thiol–ene photopolymerization under low intensity UV-A and visible light sources

The performance of a series of 2-amino-4,6-diphenyl-benzene-1,3-dicarbonitrile derivatives as visible light sensitizers for diphenyliodonium salt for enabling photopolymerization at different irradiation wavelengths was studied.

Diphenyliodonium Ion/Et3N Promoted Csp2-H Radical Phosphorylation of Enamides.

This work reports a simple and efficient method for the direct phosphorylation of enamide under metal-free conditions. The P-centered radicals, derived from secondary phosphine oxides, are generated under mild reaction conditions in the presence of diphenyliodonium salt and Et3N and are introduced onto a range of enamides in good isolated yields. The method features broad substrate scope, good functional group tolerance, and efficient scale-up.

Bond strength of experimental adhesives with 10-MDP and diphenyl-iodonium salt

Bond strength of experimental adhesives with 10-MDP and diphenyl-iodonium salt

Synthesis and interconversions of reduced, alkali-metal supported iron-sulfur-carbonyl complexes.

We report the synthesis, interconversions and X-ray structures of a set of [mFe-nS]-type carbonyl clusters (where S = S2-, S22- or RS-; m = 2-3; n = 1-2). All of the clusters have been identified and characterized by single crystal X-ray diffraction, IR and 13C NMR. Reduction of the parent neutral dimer [μ2-(SPh)2Fe2(CO)6] (1) with KC8 affords an easily separable ∼1 : 1 mixture of the anionic, dimeric thiolate dimer K[Fe2(SPh)(CO)6(μ-CO)] (2) and the dianionic, sulfido trimer [K(benzo-15-crown-5)2]2[Fe3(μ3-S)(CO)9] (3). Oxidation of 2 with diphenyl-disulfide (Ph2S2) cleanly returns the starting material 1. The Ph-S bond in 1 can be cleaved to form sulfide trimer 3. Oxidation of sulfido trimer 3 with [Fc](PF6) in the presence of S8 cleanly affords the all-inorganic persulfide dimer [μ2-(S)2Fe2(CO)6] (4), a thermodynamically stable product. The inverse reactions to form 3 (dianion) from 4 (neutral) were not successful, and other products were obtained. For example, reduction of 4 with KC8 afforded the mixed valence Fe(i)/Fe(ii) species [((FeS2)(CO)6)2FeII]2- (5), in which the two {Fe2S2(CO)6}2- units serve as bidendate ligands to a Fe(ii) center. Another isolated product (THF insoluble portion) was recrystallized in MeCN to afford [K(benzo-15-crown-5)2]2[((Fe2S)(CO)6)2(μ-S)2] (6), in which a persulfide dianion bridges two {2Fe-S} moieties (dimer of dimers). Finally, to close the interconversion loop, we converted the persulfide dimer 4 into the thiolate dimer 1 by reduction with KC8 followed by reaction with the diphenyl iodonium salt [Ph2I](PF6), in modest yield. These reactions underscore the thermodynamic stability of the dimers 1 and 4, as well as the synthetic and crystallization versatility of using the crown/K+ counterion system for obtaining structural information on highly reduced iron-sulfur-carbonyl clusters.

Metal-Free Synthesis of 6-Phosphorylated Phenanthridines: Synthetic and Mechanistic Insights.

A novel and efficient method for the generation of phosphinoyl radicals from the combination of diphenyliodonium salt (Ph2I+,-OTf) with triethylamine (Et3N) in the presence of secondary phosphine oxides is reported. By employing this practical and simple approach, a large variety of 6-phosphorylated phenanthridines have been synthesized through the addition of phosphinoyl radicals to isonitriles as radical acceptors. The reaction works smoothly in the absence of any transition metal or photocatalyst. On the basis of electron paramagnetic resonance (EPR) and density functional theory (DFT) calculations, the mechanism of this reaction is discussed.

C[sbnd]H bond arylation of anilides inside copper-exchanged zeolites

Syntheses of fine-chemicals using heterogeneous catalysts have tremendous industrial potentials, yet CH functionalization studies have been largely focused on homogeneous catalysis. We report here the first meta-selective CH bond arylation of anilides inside copper-exchanged zeolites. Mid- or large-pore zeolite frameworks are selected as supports to access large organic molecules, and atomically distributed copper catalysts exhibit high activities (84–90% conversions) toward direct arylation of anilides with diphenyliodonium salt on 0.5mol% copper concentration. Computational studies indicate the well-fitted copper-aryl complexes inside zeolite frameworks. Electron micrographs, elemental analyses, and reusability study show no observable leaching of catalytically active copper species during the reactions tested. These results demonstrate the practical synthetic potential of copper-exchanged zeolites as promising supported molecular catalysts to afford biaryl motifs-containing compounds with high catalytic activity, chemical stability, and recyclability.

Diphenyliodonium‐Catalyzed Fluorination of Arynes: Synthesis of ortho‐Fluoroiodoarenes

AbstractDescribed is a one‐pot vicinal fluorination‐iodination of arynes at room temperature. The diphenyliodonium salt proved to be a privileged catalyst for this nucleophilic fluorination process using CsF as a fluorine source, and a subsequent facile electrophilic iodination with C4F9I was also found to be crucial to ensure the efficient fluorination. This new synthetic protocol has a broad substrate scope under mild reaction conditions.

Diphenyliodonium-Catalyzed Fluorination of Arynes: Synthesis of ortho-Fluoroiodoarenes.

Described is a one-pot vicinal fluorination-iodination of arynes at room temperature. The diphenyliodonium salt proved to be a privileged catalyst for this nucleophilic fluorination process using CsF as a fluorine source, and a subsequent facile electrophilic iodination with C4 F9 I was also found to be crucial to ensure the efficient fluorination. This new synthetic protocol has a broad substrate scope under mild reaction conditions.

Degree of conversion, depth of cure, and color stability of experimental dental composite formulated with camphorquinone and phenanthrenequinone photoinitiators.

This study evaluated the applicability of 9,10-phenanthrenequinone (PQ) in experimental dental composites. Camphorquinone (CQ), PQ, ethyl 4-N,N-dimethylaminobenzoate (EDMAB) and diphenyliodonium salt (DPI) were employed. A mixture of 2,2-bis(4-[2-hydroxy-3-methacryloxypropoxy]phenyl)-propane/triethylene glycol dimethacrylate (60:40%) and silanated glass filler at 60% were used. A two-peak-based light-emitting diode (LED) was used. The photoinitiator absorption and the light emission spectra were determined by a Ultraviolet-visible spectroscopy and a spectroradiometer, respectively. Relative photon absorption (RPabs) was calculated. Fourier-transformed infrared spectroscopy analysis was used to determine the degree of conversion (DC). The optical properties were determined with a spectrophotometer. Depth of cure was assessed from adapted International Organization for Standardization (ISO) 4049. Results were analyzed with descriptive analysis, analysis of variance, and Tukey's test (α = 5%). PQ showed higher RPabs than CQ. Regarding the DC, CQ + EDMAB (control), CQ + EDMAB + DPI, PQ + DPI, and PQ + EDMAB + DPI produced statistically similar results. Groups formulated with CQ presented higher depth of cure. Only the group formulated with CQ + EDMAB presented satisfactory color stability (ΔE < 3.3). PQ presented higher RPabs than CQ and it was able to produce DC similar to CQ + EDMAB, when used with DPI. However, groups formulated with PQ produced lower depth of cure, greater yellowing, and less color stability than the traditional combination CQ and amine. Although research with novel photoinitiator systems should be encouraged, the traditional camphorquinone and amine pair remains as a reliable combination for the formulation of dental composites.

Efficient visible photoinitiator containing linked dye-coinitiator and iodonium salt for free radical polymerization

Abstract Dye-linked initiators consisting of erythrosine B as a chromophore and ethyl 4-dimethylaminobenzoate as an electron donor linked by a different number of methylene units were prepared to achieve efficient photoinitiators of free radical polymerization in a visible-light region. The relative photoinitiating efficiencies of novel photoinitiators in photopolymerization of acrylates were evaluated. The results showed that the photoinitiating system composed of the dye-linked dyad with short methylene unit chain and diphenyliodonium salt exhibited a remarkable increase in the photoinitiation ability compared to unlinked three-component system. The enhancement mechanism aroused by the onium salt was investigated. These results showed that the excellent initiating efficiency of this system could be attributed to the favorable intramolecular photoinduced electron transfer and the close distance between reaction components caused by electrostatic interactions. This result demonstrated the importance and potential of the linked photoinitiator in the design of new efficient photoinitiators.