Search Results (73)

Non-metallic hydride donors have emerged as an interesting, highly tunable class of compounds capable of CO₂ reduction, with benzimidazoles being simple, yet efficient and regenerable, representatives. In this work, the role of superbases as auxiliary groups attached to the benzimidazole framework was investigated using the CPCM(CH₃CN)/ωB97xD/aug-cc-pVTZ//CPCM(CH₃CN)/ωB97xD/6-31+G(d,p) approach. Three modes of operation were assessed through hydricity calculations and the modeling of two different CO₂ reduction mechanisms. Among the superbases considered, phosphazene substituents yielded the largest increase in the hydride donation ability, lowering hydricity by 6 kcal mol⁻¹ relative to 2-methylbenzimidazole, with the α-substitution exerting a stronger effect than β-substitution. For most systems, changes in hydricity correlate with changes in aromaticity, except in systems where steric congestion limits optimal substituent alignment. CO₂ activation pathways encompassing guanidine/CO₂ hydrogen bonding and guanidinium carboxamidine formation were modeled. In the former, transition state structures were significantly stabilized, and the overall exergonicity of the reduction is enhanced. Also, utilizing the longer and more flexible linker additionally decreases the barrier for the reaction. The carboxamidine pathway is disfavored because of the high stability of the carboxamidine intermediate and low barrier for the C–N bond cleavage, which reverses the mechanism to the reduction of isolated CO₂. Full article

Porous highly cross-linked polymer (PIP) was synthesized by a polycondensation reaction between hexachlorocyclotriphosphazene and piperazine. The obtained polymer has a surface area of 76.9 m²/g and a mesoporous structure. After carbonization, the obtained product (PIP-C) has a surface area of 177 m²/g. The obtained carbon product contained nitrogen and phosphorus heteroatoms, which leads to a higher specific capacitance (155.6 F/g) and catalytical activity in the electroreduction of oxygen (15.9 A/g). This work shows the possibility of the use of such porous phosphazene polymers as precursors for heteroatom-doped carbon materials, which might be used in electrochemical devices like electrodes for supercapacitors or metal-free electrocatalysts in fuel cells. Full article

Silicon-graphite anodes offer a practical route to increase the energy density of lithium-ion batteries (LIBs), but their widespread adoption is hampered by cyclic instability due to huge volume changes of silicon during lithiation/delithiation process. Another fallout of LIBs capacity gain is growing safety concerns due to fire risks, associated with the uncontrolled release of chemical energy. Herein, we test a hexakis(fluoroethoxy)phosphazene (HFEPN) as a multifunctional electrolyte additive designed to mitigate both issues. The flammability of HFEPN-containing electrolytes was evaluated using a self-extinguishing time test, while the electrochemical performance was assessed in Si/C composite||NMC pouch cells under a progressively accelerated cycling protocol. It is shown that the additive fully imparts flame-retardant properties to the electrolyte at a 15 wt% loading. Despite forming a more stable solid–electrolyte interphase (SEI) with enhanced interfacial kinetics the additive did not improve the cycling stability of the Si/C-based cells. The cells with 15 wt% HFEPN retained 43% of capacity after 70 cycles, comparable to 46.5% for the reference electrolyte. The diffusion limitations imposed by the increased electrolyte viscosity are assumed to offset the interfacial benefits of the additive. Thus, alongside the improved synthetic route, this study demonstrates that while HFEPN functions as an effective flame retardant and SEI modifier, its practical benefits for silicon anodes are limited at high concentrations by detrimental effects on electrolyte transport properties and should be improved in future molecular design efforts. Full article

Poly(organo)phosphazenes (PPZs) are increasingly recognized as versatile biomaterials for drug delivery applications in nanomedicine. Their unique hybrid structure—featuring an inorganic backbone and highly tunable organic side chains—confers exceptional biocompatibility and adaptability. Through precise synthetic methodologies, PPZs can be engineered to exhibit a wide spectrum of functional properties, including the formation of multifunctional nanostructures tailored for specific therapeutic needs. These attributes enable PPZs to address several critical challenges associated with conventional drug delivery systems, such as poor pharmacokinetics and pharmacodynamics. By modulating solubility profiles, enhancing drug stability, enabling targeted delivery, and supporting controlled release, PPZs offer a robust platform for improving therapeutic efficacy and patient outcomes. This review explores the fundamental chemistry, biopharmaceutical characteristics, and biomedical applications of PPZs, particularly emphasizing their role in zero-dimensional nanotherapeutic systems, including various nanoparticle formulations. PPZ-based nanotherapeutics are further examined based on their drug-loading mechanisms, which include electrostatic complexation in polyelectrolytic systems, self-assembly in amphiphilic constructs, and covalent conjugation with active pharmaceutical agents. Together, these strategies underscore the potential of PPZs as a next-generation material for advanced drug delivery platforms. Full article

Exploration of new ways for the direct preparation of cross-linked structures is a significant problem in terms of materials for biomedical applications, lithium batteries electrolytes, toughening of thermosets (epoxy, benzoxazine, etc.) with interpenetrating polymer network, etc. The possibility to utilize hydrosilylation and Piers–Rubinsztajn reactions to obtain cross-linked model phosphazene compounds containing eugenoxy and guaiacoxy groups has been studied. It was shown that Piers–Rubinsztajn reaction cannot be used to prepare phosphazene-based tailored polymer matrix due to the catalyst deactivation by nitrogen atoms of main chain units. Utilizing the hydrosilylation reaction, a series of cross-linked materials were obtained, and their properties were studied by NMR spectroscopy, FTIR, DSC, and TGA. Rheological characterizations of the prepared tailored matrices were conducted. This work showed a perspective of using eugenoxy functional groups for the preparation of three-dimensional hybrid phosphazene/siloxane-based materials for various applications. Full article

In recent years, polyphosphazene (POP) membranes have been gaining more and more attention owing to their excellent pervaporation desulfurization performance. To develop new POP membranes, three kinds of POPs with different side groups, Poly[bis(trifluoroethoxy)phosphazene] (PTFEP), Poly[bis(trifluorobutoxy)phosphazene] (PTFBP), and Poly[bis(octafluoropentyloxy)phosphazene] (POFPP), were synthesized. The NMR spectroscopy demonstrated that POPs with a designed structure were successfully prepared. Subsequently, the composite membranes based on these POPs were fabricated by solution casting. The influence of side groups on the desulfurization performance of membranes was systematically evaluated via a pervaporation test. Among these membranes, the PTFBP membrane exhibited the highest separation efficiency, significantly outperforming other membrane types with a permeation flux of 0.284 kg·m⁻²·h⁻¹ at 200 ppm and 85 °C, along with a sulfur enrichment factor of 26.48. In addition, the effects of temperature and feed concentration on separation performance were investigated in detail. Full article

Chlorpyrifos is one of the most toxic organophosphate pesticides, prompting its ban in Europe in 2020. Consequently, developing a detection method that is both selective and sensitive is essential for protecting human health and the environment. In this study, we report for the first time a fluorescent probe based on an oxime for the direct detection of chlorpyrifos. 9-fluorenone oxime, upon deprotonation with a phosphazene base, undergoes a nucleophilic attack on chlorpyrifos, resulting in a significant alteration of its fluorescence properties. Following careful optimization, the method demonstrated excellent linearity (R² = 0.98) over a concentration range of 350 to 6980 μg/L, with a limit of detection of 15.5 μg/L. Furthermore, the probe was successfully applied to chlorpyrifos detection in water samples, yielding satisfactory results. This approach effectively overcomes the stability limitations of enzyme-based fluorescent sensors, offering a robust and innovative solution for the detection of organophosphate pesticides. Full article

This review examines representatives of organocyclophosphazenes that can act against tumor cells of the ovaries, prostate gland, mammary gland, and colon, etc., and have antimicrobial action against mycobacteria M. tuberculosis, Gram-positive bacteria B. cereus, Gram-negative bacteria K. pneumaniae, fungi of the genus Candida, and other microorganisms. Cyclomatric phosphazenes can be used as carriers of physiologically active substances and in the field of detection, as well as gels for wound surgery and drug delivery platforms. In gels, cyclophosphazenes are used as cross-linking agents. Cyclophosphazenes containing multiple bonds in organic radicals are proposed to be used in dentistry as additives to basic dental compositions. Particular attention in the review is paid to the cytotoxic and antimicrobial action of materials containing cyclophosphazenes and their advantages over commercial physiologically active substances. The review presents the prospects for the practical application of cyclophosphazenes containing various functional groups (chalcone, anthraquinone, pyrrolidine, morpholine, and ferrocene, etc.) in pharmaceuticals. The review may be of interest to researchers working in the field of organoelement chemistry, medicine, and pharmacy. Full article

This study introduces a metal-free binary catalytic system for coupling CO₂ with cyclohexane oxide (CHO) under mild conditions, allowing for tunable product selectivity. Using trans-cyclohexane diol (trans-CHD) and phosphazene superbase (P₄) as catalysts, the system selectively produces cyclic carbonates and oligocarbonates at 1 bar CO₂ pressure and 80 °C. By adjusting the catalyst ratio, varying proportions of cis-cyclohexane carbonate (cis-CHC), trans-cyclohexane carbonate (trans-CHC), and oligocarbonate are achieved, with 51 mol% CHO conversion and respective selectivities of 36%, 31%, and 33%. The catalytic efficiency and precise control of product outcomes underscore this system’s potential. Full article

This study investigated the application of poly[bis (ethylmethionato) phosphazene] (PαAPz-M) electrospun fibers in tissue engineering, focusing on their reactive oxygen species (ROS) scavenging capabilities and material-directed cell behavior, including the influence of their degradation products on cell viability and differentiation, and the scaffold topography’s influence on cell alignment. The ROS scavenging ability of PαAPz-M was assessed by DPPH assay, and then PαAPz-M’s protection against exogenous ROS was studied. The results showed enhanced cell viability on PαAPz-M fiber mats under oxidative stress conditions. This study also investigated the effects of the degradation products of PαAPz-M on cell viability and osteogenic differentiation. It was observed that the late-stage degradation product, phosphoric acid, can significantly influence the osteogenic differentiation of MSCs. In contrast, methionine, which is the early-stage degradation product, showed a minimal influence. Additionally, the study fabricated fiber mats that can lead to enhanced cell alignment while maintaining high porosity. Collectively, this study expanded the applications of PαAPz-M fiber mat protection against oxidative stress and guiding osteogenic differentiation and cell alignment. Full article

Linear chlorinated phosphazene acid is prepared using PCl₅ and NH₄Cl as raw materials. Using hexaethylcyclotrisiloxane as the monomer, 1,1,3,3-tetramethyldisiloxane or 1,3-divinyl-1,1,3,3-tetramethyldisiloxane as the end-capping agent, and linear chlorinated phosphazene acid as the catalyst, polydiethylsiloxane oligomers terminated with active Si-H or Si-CH=CH₂ groups have been prepared. Using hexaethylcyclotrisiloxane and 1,3,5,7-octamethylcyclotetrasiloxane as comonomers, 1,1,3,3-tetramethyldisiloxane or hexamethyldisiloxane as the end-capping agent, or using hexaethylcyclotrisiloxane and octamethylcyclotetrasiloxane as comonomers, 1,1,3,3-tetramethyldisiloxane as the end-capping agent, copolymers containing active Si-H bonds and dimethylsiloxane segments have been prepared under the catalysis of linear chlorinated phosphazene acid. The effects of catalyst dosage, reaction temperature, reaction time, end-capping agent, and polymerization monomer dosage on polymer yield and structure were investigated. Using 300 ppm of linear chlorinated phosphazene acid, oligomers and copolymers containing an active Si-H bond and diethylsiloxane segment were prepared under mild conditions. The molecular weight of the obtained polymers was close to their designed values, but their PDI values were small. The highest yield of α, ω-bisdimethylsiloxyl-terminated PDES oligomers reached 93%. Using oligomers and copolymers containing Si-H bonds and diethylsiloxane segments as crosslinkers, a silicone gel containing diethylsiloxane segments was prepared by hydrosilylation reaction. With the introduction of a diethylsiloxane segment, the glass transition temperature of the silicone gel decreased relative to that of the PDMS oligomer, but the temperature at 5% weight loss in nitrogen atmosphere decreased from 347 °C to 312 °C. The mechanism of the ring-opening polymerization of hexaethylcyclotrisiloxane catalyzed by linear chlorinated phosphazene acid is also discussed. Full article

Polycarbonate/acrylonitrile butadiene styrene (PC/ABS) blends are widely used as engineering plastic alloys; however, they have a low fire safety level. To improve the flame-retardant property of PC/ABS, a zirconium-based metal-organic framework material (UiO-66) was synthesized with zirconium chloride and terephthalic acid and used as a flame-retardant cooperative agent. Its flame-retardant performance and mode of action in the PC/ABS blends were carefully investigated. The results showed that UiO-66 had good thermal stability and delayed the pyrolysis of the materials, thus significantly enhancing the efficiency of intumescent flame retardants. By compounding 7.0 wt% hexaphenyloxy-cyclotri-phosphazene (HPCTP) with 3.0 wt% UiO-66, the PC/ABS blends reached a limiting oxygen index value of 27.0% and V0 rating in the UL-94 test, showing significantly improved resistance to combustion dripping. In addition, UiO-66 enhanced the smoke and heat suppression characteristics of the intumescent flame-retardant materials. Finally, the flame-retardant mode of action in the blends was indicative of UiO-66 having a cooperative effect on the flame-retardant performance of PC/ABS/HPCTP materials. This work provides good ideas for further development of the flame-retardant ABS/PC. Full article

Starting from poly(4-vinylpyridine) ((P4VP)_n), poly(2-vinylpyridine) ((P2VP)_n), and [N=P(O₂CH₂CF₃)]_m-b-P2VP₂₀ block copolymers, a series of metal-containing homopolymers, (P4VP)_n⊕MX_m, (P2VP)_n⊕MX_m, and [N=P(O₂CH₂CF₃)]_m-b-P2VP₂₀]⊕MX_m MX_m = PtCl₂, ZnCl₂, and Eu(NO₃)₃, have been successfully prepared by using a direct and simple solution methodology. Solid-state pyrolysis of the prepared metal-containing polymeric precursors led to the formation of a variety of different metallic and metal oxide nanoparticles (Pt, ZnO, Eu₂O₃, and EuPO₄) depending on the composition and nature of the polymeric template precursor. Thus, whereas Eu₂O₃ nanostructures were obtained from europium-containing homopolymers ((P4VP)_n⊕MX_m and (P2VP)_n⊕MX_m), EuPO₄ nanostructures were achieved using phosphorus-containing block copolymer precursors, [N=P(O₂CH₂CF₃)]_m-b-P2VP₂₀]⊕MX_m with MX_m = Eu(NO₃)₃. Importantly, and although both Eu₂O₃ and EuPO₄ nanostructures exhibited a strong luminescence emission, these were strongly influenced by the nature and composition of the macromolecular metal-containing polymer template. Thus, for P2VP europium-containing homopolymers ((P4VP)_n⊕MX_m and (P2VP)_n⊕MX_m), the highest emission intensity corresponded to the lowest-molecular-weight homopolymer template, [P4VP(Eu(NO₃)₃]₆₀₀₀, whereas the opposite behavior was observed when block copolymer precursors, [N=P(O₂CH₂CF₃)]_m-b-P2VP₂₀]⊕MX_m MX_m= Eu(NO₃)₃, were used (highest emission intensity corresponded to [N=P(O₂CH₂CF₃)]₁₀₀-b-[P2VP(Eu(NO₃)₃)_x]₂₀). The intensity ratio of the emission transitions: ⁵D₀ → ⁷F₂/⁵D₀ → ⁷F₁, suggested a different symmetry around the Eu³⁺ ions depending on the nature of the polymeric precursor, which also influenced the sizes of the prepared Pt°, ZnO, Eu₂O₃, and EuPO₄ nanostructures. Full article

Polycarbonate (PC) as a widely used engineering plastic that shows disadvantages of flammability and large smoke production during combustion. Although many flame-retardant PCs have been developed, most of them show enhanced flame retardancy but poor smoke suppression or worsened mechanical performance. In this work, a novel nitrogen–phosphorus–sulfur synergistic flame retardant (Pc-FR) was synthesized and incorporated into PC with polytetrafluoroethylene (PTFE). The extremely low content of PC-FR (0.1–0.5 wt%) contributes significantly to the flame retardancy, smoke suppression and mechanical performance of PC. PC/0.3 wt% Pc-FR/0.3 wt% PTFE (PC-P0.3) shows the UL-94 V-0 and LOI of 33.5%. The PHRR, THR, PSPR, PCO and TCO of PC-P0.3 decreased by 39.44%, 14.38%, 17.45%, 54.75% and 30.61%, respectively. The impact strength and storage modulus of PC-P0.1 increased by 7.7 kJ/m² and 26 MPa, respectively. The pyrolysis mechanism of PC-P0.3 is also revealed. The pyrolysis mechanism of PC-P0.3 is stochastic nucleation and subsequent growth and satisfies the Aevrami–Erofeev equation. The reaction order of PC-P0.3 is 1/2. The activation energy of PC-P0.3 is larger than PC-0, which proves that the Pc-FR can suppress the pyrolysis of the PC. This work offers a direction on how to design high-performance PC. Full article

Protection against fire and the corrosion of metals is necessary to ensure human safety. Most of the fire and corrosion inhibitors do not meet the ecological requirements. Therefore, effective and ecological methods of protecting metals are currently a challenge for researchers. In this work, the influence of hexakis(4-(hydroxymethyl)phenoxy)cyclotriphosphazene (HHPCP) on the characteristics of powder coatings was examined. The coatings’ properties were investigated by measuring the roughness, hardness, adhesion to the steel surface, cupping, gloss, scratch resistance, and water contact angle. The thermal stability was studied by furnace test and TGA analysis. The corrosion resistance test was carried out in a 3.5% NaCl solution. The distribution of phosphazene-derived segments in the coating was examined by GD-EOS analysis. Modified coatings show better corrosion and thermal resistance and can be used for the protection of the steel surface. Their better corrosion resistance is due to the electroactive properties of the phosphazene ring and its higher concentration at the coating surface, confirmed by GD-EOS analysis. The increase in thermal resistance is due to the effect of the formation of phosphoric metaphosphoric and polyphosphoric acids during the decomposition of HHCPC, which remain in the condensed char phase and play a crucial role in surface protection. Full article