Organic Phosphorus Compounds Research Articles

Formaldehyde preservation for deferred measurements of alkaline phosphatase activities in marine samples

Alkaline phosphatases are the main enzymes required by microorganisms to hydrolyse organic phosphorus into available phosphate in aquatic environments. The investigations of alkaline phosphatase activity (APA) usually generate numerous samples (size fractionation, Michaelis-Menten kinetics). Therefore, convenient and reliable preservation of incubated samples for a deferred analysis would be very useful when measurements cannot be performed right away. The APA of marine pond waters was measured using 4-Methylumbelliferyl phosphate (MUF-P) as the fluorogenic substrate modelling natural organic phosphorus compounds. Where typical inhibitors of other enzymatic activities, such as 1% sodium dodecyl sulfate, mercuric chloride, or buffered solutions of ammonium and glycine, failed to stop APA, the addition of formaldehyde efficiently inhibited APA. The effect of formaldehyde was the strongest with the highest concentration tested (4% final concentration) and in buffered (pH 8) solutions. Since a slow and gradual increase in APA may persist with time, the combination of the addition of 4% buffered formaldehyde with immediate freezing is the best method to entirely inhibit APA. The maximal rate of hydrolysis (Vmax) and the Michaelis constant (Km) of formaldehyde (4%)-inhibited samples did not significantly change during storage at -20 °C for 11 days. The method was successfully tested on samples with extremely high values of APA (15000–40000 nM h−1) that were preserved for 1 month at -20 °C (98% inhibition). This method is a reliable and useful means of preserving incubated samples, and it provides convenient controls for background fluorescence of water and substrate, without provoking abiotic hydrolysis of the substrate.

Phosphate diester utilization by marine diazotrophs Trichodesmium erythraeum and Crocosphaera watsonii

In the phosphate-depleted oligotrophic ocean, microbes utilize various dissolved organic phosphorus (P) compounds as alternative P sources, using enzymes such as alkaline phosphatases. However, knowledge of such P acquisition mechanisms is limited, especially in association with the physiology of nitrogen-fixing organisms, which play a substantial role in marine biogeochemical cycling. We show that nonaxenic clonal cultures of 2 oceanic diazotrophs,Trichodesmium erythraeumandCrocosphaera watsonii, have the ability to utilize phosphate diester as their sole P source, using a model artificial compound—bis-p-nitrophenyl phosphate (bisNPP). Although both diazotroph cultures likely preferred phosphate monoester to diester, the expressed diesterase activity was theoretically sufficient to fulfill their P demands, and they showed significant growth in bisNPP-added media. Interestingly, a distinct difference in their growth trends was observed, with faster onset of growth byC. watsoniiand delayed onset of growth byT. erythraeum. This indicates that theC. watsoniiconsortium can effectively and rapidly assimilatein situdiesters as alternative P sources in the field. Nonetheless, when considering the poor bisNPP utilization reported from other marine phytoplankton taxa, our results indicate that the utilization of particular diester compounds is a notable and advantageous strategy for both diazotroph consortia to alleviate P limitation in the oligotrophic ocean.

Optimization of soapstock splitting process to reduce the concentration of impurities in wastewater

Soapstock is a by-product of crude vegetable oil refining which contains soaps, neutral oil and different impurities removed from oil during the process. This substance is predominantly treated with mineral acid (splitting) to recover fatty acids from soaps. High treatment costs make it advisable to reduce the pollutants of this wastewater “at source”. The Response Surface Methodology was employed to optimize the splitting of the rapeseed soapstock. The experiments were conducted in an industrial plant operating on a continuous basis. The study factors included: phosphorus content in oil (X1), flow rate of NaOH to the saponification section (X2), saponification temperature (X3), soapstock splitting temperature (X4) and pH (X5). The concentration of organic phosphorus compounds (Porg), COD and the acid number (AN) of post-refinery fatty acids were measured during the experiments. All the study factors substantially affect the AN, whereas the pH value during soapstock splitting has no material effect on Porg concentration, and soapstock splitting temperature has no material effect on COD. Phosphorus content in oil has a very large effect on all the study values, and when was reduced, the wastewater concentrations of Porg and COD dropped considerably while the AN of post-refinery fatty acids increased. For average value of X1 = 185 mg/kg, the optimal conditions were as follows: X2 = 3.08 kg/h, X3 = 137 °C, X4 = 91.5 °C and X5 = 3.50. It is possible under such conditions to produce post-refinery fatty acids with an of 171 mg KOH/g and wastewater with Porg concentration 425 mg/dm3 and COD 7958 mg/dm3. The Response Surface Methodology is highly suitable for mathematical modelling of the rapeseed soapstock splitting process under industrial conditions.

REACTIVITY OF NUCLEOPHILES AND α-EFFECT IN SUBSTITUTION PROCESSES AT ELECTRON - DEFICIENCY CENTERS (Part 2)

The review analyzes issues related to the reactivity of nucleophiles and the manifestation of the α-effect in substitution processes at electron-deficient centers. The fundamental aspects of this phenomenon, as well as the possibilities and prospects of using α-nucleophiles in systems for the highly efficient degradation of substrates - ecotoxicants of various natures, are discussed. In the first part of the review such aspects were observed: inorganic α-nucleophiles as the most effective class of reagents for the decomposition of organic phosphorus compounds, hydroxylamine, its N-alkyl derivatives, oximes, and hydroxamic acids, reactivity of the НОО– anion in the processes of acyl group transfer, reactivity of oximate ions, inorganic α-nucleophiles as the basis of formulations for the degradation of neurotoxins, vesicants, and organophosphorus pesticides, design of inhibited acetylcholinesterase reactivators based on hydroxylamine derivatives, ways of structural modification of α-nucleophiles and systems based on them. The data on the reactivity of typical inorganic α-nucleophiles in the cleavage of acyl-containing substrates, including phosphorus acid esters, which provide abnormally high reaction rates in comparison with other supernucleophiles, are analyzed. Various types of such α-nucleophiles, features of their structure and reactivity are considered. It was shown that an important feature of hydroxylamine, oximes, and hydroxamic acids is the presence of a fragment with adjacent O and N (–N – O – H) atoms containing one or more lone electron pairs, which determines their belonging to the class of α-nucleophiles. It has been shown that a many of factors can be responsible for the manifestation of the α-effect and its magnitude, the main of which is the destabilization of the ground state of the nucleophile due to repulsion of lone electron pairs, stabilization of the transition state, the unusual thermodynamic stability of reaction products, solvation effects of the solvent, type of hybridization of the electrophilic center, etc.

Intraspecific Variation in Growth and Alkaline Phosphatase Activity of Cylindrospermopsis raciborskii Strains in Response to Different Phosphorus Concentrations and Sources

The cyanobacterial species C. raciborskii are ubiquitous in tropical regions, and its successful invasion into temperate zones has been partially attributed to its ability of survival in low P availability and the existence of multiple ecotypes. To explore the physiological response of different strains to phosphorus fluctuations, four strains of C. raciborskii isolated from the Zhenhai Reservoir were used to investigate their growth and alkaline phosphatase (ALP) activity at different inorganic phosphorus (Pi) concentrations (HP=7.13 mg ·L-1, MP=0.64 mg ·L-1, LP=0.03 mg ·L-1) and different phosphorus forms [dipotassium hydrogen phosphate (K2HPO4), sodium pyrophosphate (K4P2 O7), sodium polyphosphate (K5P3O10), D-glucose-6-phosphate (D-G-6-P), adenosine triphosphate (ATP), cyclic adenosine monophosphate (cAMP)]. Four C. raciborskii strains showed a similar growth response to phosphate changes: their biomass increased with an increase in Pi concentrations, while the ALP activity showed the opposite trend. The ALP activity of C. raciborskii N8 was significantly lower than that of other three strains, regardless of inorganic phosphorus concentrations, suggesting that this strain had a higher adaptability to phosphorus fluctuations. When cultured with different phosphorus forms, the biomass of C. raciborskii N8 and N9 in three dissolved inorganic phosphorus (DIP) compounds were significantly higher than those in three dissolved organic phosphorus (DOP) compounds, with the maximum and minimum specific growth rate in K2HPO4and ATP treatments, respectively. C. raciborskii preferred DIP although they can also utilize DOP to sustain its growth. Under the DOP conditions, the ALP activity of C. raciborskii N8 in the ATP treatment was significantly higher than that in the other two organic phosphorus compounds, while we did not observe similar results in C. raciborskii N9, indicating that strain N8 was more sensitive to DIP deficiency. Our results showed an intraspecific variation within C. raciborskii strains from the same reservoir. Compared with the other strains, strain N8 represented better adaptability to phosphorus fluctuations and DIP deficiency. Variations within C. raciborskii strains may make this species more adaptable to environmental changes and enhance its competitive advantage.

REACTIVITY OF NUCLEOPHILES AND α-EFFECT IN SUBSTITUTION PROCESSES AT ELECTRON - DEFICIENCY CENTERS

The review analyzes issues related to the reactivity of nucleophiles and the manifestation of the α-effect in substitution processes at electron-deficient centers. The fundamental aspects of this phenomenon, as well as the possibilities and prospects of using α-nucleophiles in systems for the highly efficient degradation of substrates - ecotoxicants of various natures, are discussed. In the first part of the review such aspects were observed: inorganic α-nucleophiles as the most effective class of reagents for the decomposition of organic phosphorus compounds, hydroxylamine, its N-alkyl derivatives, oximes, and hydroxamic acids, reactivity of the НОО– anion in the processes of acyl group transfer, reactivity of oximate ions, inorganic α-nucleophiles as the basis of formulations for the degradation of neurotoxins, vesicants, and organophosphorus pesticides, design of inhibited acetylcholinesterase reactivators based on hydroxylamine derivatives, ways of structural modification of α-nucleophiles and systems based on them. The data on the reactivity of typical inorganic α-nucleophiles in the cleavage of acyl-containing substrates, including phosphorus acid esters, which provide abnormally high reaction rates in comparison with other supernucleophiles, are analyzed. Various types of such α-nucleophiles, features of their structure and reactivity are considered. It was shown that an important feature of hydroxylamine, oximes, and hydroxamic acids is the presence of a fragment with adjacent O and N (–N – O – H) atoms containing one or more lone electron pairs, which determines their belonging to the class of α-nucleophiles. It has been shown that a many of factors can be responsible for the manifestation of the α-effect and its magnitude, the main of which is the destabilization of the ground state of the nucleophile due to repulsion of lone electron pairs, stabilization of the transition state, the unusual thermodynamic stability of reaction products, solvation effects of the solvent, type of hybridization of the electrophilic center, etc.

History of Foreign Studies of Organophosphate Induced Delayed neuropathy

Сertain organophosphates are highly toxic and can be used as chemical warfare agents. However, some classes of organic phosphorus compounds can cause so-called delayed neurotoxicity. Since the discovery of this phenomenon in 1899, extensive research has been conducted on delayed neurotoxicity caused by organophosphates. Mass poisoning of residents of the United States and Morocco in the last century demonstrated the high danger of substances that cause neurotoxicity, and gave a powerful impetus to research into this phenomenon. In addition to delayed effects, some phosphorus compounds potentiate the action of already known chemical warfare agents, increasing their toxicity by more than 10 times. Research in this direction is conducted under the auspices of the defense departments of the United States, Canada and the Netherlands. The wide distribution of phosphorus compounds in various industries and agriculture, the long hidden period and the irreversibility of lesions caused by neurotoxic organic phosphorus compounds, cause their potential threat to the security of the Russian Federation

Butaphosphan Effects on Glucose Metabolism Involve Insulin Signaling and Depends on Nutritional Plan.

Butaphosphan is an organic phosphorus compound used in several species for the prevention of rapid catabolic states, however, the mechanism of action remains unclear. This study aimed at determining the effects of butaphosphan on energy metabolism of mice receiving a normal or hypercaloric diet (HCD) and submitted or not to food restriction. Two experiments were conducted: (1) during nine weeks, animals were fed with HCD (n = 28) ad libitum, and at the 10th week, were submitted to food restriction and received butaphosphan (n = 14) or saline injections (n = 14) (twice a day, for seven days) and; (2) during nine weeks, animals were fed with a control diet (n = 14) or HCD (n = 14) ad libitum, and at the 10th week, all animals were submitted to food restriction and received butaphosphan or saline injections (twice a day, for seven days). In food restriction, butaphosphan preserved epididymal white adipose tissue (WAT) mass, increased glucose, NEFA, and the HOMA index. In mice fed HCD and submitted to food restriction, the butaphosphan preserved epididymal WAT mass. Control diet influences on PI3K, GCK, and Irs1 mRNA expression. In conclusion, butaphosphan increased blood glucose and reduced fat mobilization in overweight mice submitted to caloric restriction, and these effects are influenced by diet.

History of Foreign Studies of Organophosphate Induced Delayed Neuropathy

Сertain organophosphates are highly toxic and can be used as chemical warfare agents. However, some classes of organic phosphorus compounds can cause so-called delayed neurotoxicity. Since the discovery of this phenomenon in 1899, extensive research has been conducted on delayed neurotoxicity caused by organophosphates. Mass poisoning of residents of the United States and Morocco in the last century demonstrated the high danger of substances that cause neurotoxicity, and gave a powerful impetus to research into this phenomenon. In addition to delayed effects, some phosphorus compounds potentiate the action of already known chemical warfare agents, increasing their toxicity by more than 10 times. Research in this direction is conducted under the auspices of the defense departments of the United States, Canada and the Netherlands. The wide distribution of phosphorus compounds in various industries and agriculture, the long hidden period and the irreversibility of lesions caused by neurotoxic organic phosphorus compounds, cause their potential threat to the security of the Russian Federation.

Removal of inorganic and organic phosphorus compounds from aqueous solution by ferrihydrite decoration onto graphene.

Existing research on phosphorus removal from wastewater mostly focused on inorganic phosphorus while ignoring organic phosphorus, which has potential bioavailability. This study aims to provide an innovation for the development of advanced treatment material for both inorganic and organic phosphorus removal in water. In this study, ferrihydrite loaded on the graphene oxide (FeOOH-GO) composite adsorbent was synthesized by surface precipitation method, and its ability to remove both phosphate and diazinon as forms of inorganic and organic phosphorous from water was investigated. Characterization of the loaded composite using X-ray diffraction (XRD), scanning electron microscope (SEM), and Fourier transform-infrared spectroscopy (FTIR) indicated that FeOOH was successfully loaded onto graphene. The results of batch adsorption experiments showed that the adsorbent could remove both inorganic and organic phosphorus compounds simultaneously from water. When FeOOH content is 40%, the equilibrium adsorption amount of FeOOH-GO composite adsorbent for phosphate and diazinon was 5.81 and 23.20mgg-1, respectively. Environmental parameters such as pH and initial concentration have important influence on phosphorus removal by FeOOH-GO composite adsorbent and the removal efficiency of the inorganic and organic phosphorus from water decreases by increasing the initial concentration of phosphate and diazinon and the pH. It was concluded that the FeOOH-GO composite adsorbent has great potential to remove both inorganic and organic phosphate simultaneously from contaminated water.

Phosphorus speciation during anaerobic digestion and subsequent solid/liquid separation

This study aims to investigate the effect of anaerobic digestion (AD) on P species and how the different species are distributed in the digestate and digestate fractions, i.e. liquid and solid fractions. To do so, six full scale AD plants were used in this work and representative biomass samples were collected for investigation. P fractionation proceeded by adopting fractionation protocols consisting in step-by-step extraction with different solvents, (i.e. NaHCO3, HCl and NaOH-EDTA). Subsequently P species in the different fractions were identified by using 31PNMR. On average, AD did not substantially affect P speciation that depended on the P-fraction content of feeds. A high NaHCO3 fraction content in the ingestate determined, also, a high content of this fraction in the digestate, with consequently lower contents of both P-HCl and P-NaOH-EDTA, i.e. digestate P-fraction contents represented an inheritance of P speciation in the ingestate. A feed effect was observed in single plants. Highest pig/cow slurry content in the feeds seemed to decrease readily soluble P (extracted with NaHCO3) content and increased P associated with both organic matter and amorphous Fe/Al in the digestate. Again, using a large amount of digestate in the feed increased P-soluble content in the digestate. 31P NMR analyses revealed that inorganic P compounds dominated the spectra of all biomasses and fractions, with orthophosphate as the predominant species. When present, organic phosphorus compounds were typically represented by monophosphate esters, DNA and phospholipids, with a predominance of monophosphate esters.

Phosphorus fractions in soil fertilised with organic waste

The aim of this study has been to evaluate the effect of sewage sludge and composted sewage sludge and municipal waste on the content of various forms of P in soil. The experiment scheme: C, control; NPK; FYM; DGSS, dried and granulated sewage sludge; CSS, composed sewage sludge; CSSS, composted sewage sludge and straw; CMMW, composted mixed municipal waste; CMGW, composted municipal green waste. The content of bound P was determined in the fractions: F1, easily soluble; F2, exchangeable; F3, organic; F4, carbonate; F5, stable organic-mineral and mineral bonds; and F6, residual. The NPK fertilisation as well as the soil fertilisation with organic substances raised the P-total content and of P bound in the fractions: F3, F4, F5 and F6. The highest amount of phosphorus in the studied soil was in fraction F3 (phosphorus in organic compounds) and the lowest in fraction F1 (phosphorus in the ionic form as H2PO4− and HPO42−). Composted sludge and straw introduced into the soil increased the content of readily soluble P (F1), while the NPK effect was reversed. NPK fertilisation and enhancement of soil organic matter (except CSSS, CMGW) led to a reduction of the P content in F2 fraction. The content of available P determined by the Egner-Riehm method depended on the content of C-organic, P-total and CEC soil. Among the determined phosphorus fractions, the content of available P was most strongly correlated with the content of P bound in the carbonate fraction (F4) and residual fraction (F6) and, less strongly, with the organic phosphorus fraction.

Dissolved organic nutrient uptake by riverine phytoplankton varies along a gradient of nutrient enrichment

The concentration of dissolved organic matter (DOM) in freshwaters is increasing in large areas of the world. In addition to carbon, DOM contains nitrogen and phosphorus and there is growing concern that these organic nutrients may be bioavailable and contribute to eutrophication. However, relatively few studies have assessed the potential for dissolved organic nitrogen (DON) or dissolved organic phosphorus (DOP) compounds to be bioavailable to natural river phytoplankton communities at different locations or times. Temporal and spatial variations in uptake, relative to environmental characteristics were examined at six riverine sites in two contrasting catchments in the UK. This study also examined how the uptake by riverine phytoplankton of four DON and four DOP compounds commonly found in rivers, varied with concentration. Total nitrogen (TN) and phosphorus (TP) concentrations, the proportion of inorganic nutrient species, and nutrient limitation varied temporally and spatially, as did the potential for DON and DOP uptake. All eight of the DOM compounds tested were bioavailable, but to different extents. Organic nutrient use depended on the concentration of the organic compound supplied, with simple compounds (urea and glucose-6-phosphate) supporting algal growth even at very low concentrations. DON use was negatively correlated with the TN and ammonia concentration and DOP use was negatively correlated with soluble reactive phosphorus (SRP) and dissolved organic carbon (DOC) concentration. The evidence indicates that DOM in rivers has been overlooked as a potential source of nutrients to phytoplankton and therefore as an agent of eutrophication.

A Novel Approach for the Quantification of Different Inorganic and Organic Phosphorus Compounds in Environmental Samples by P L2,3-Edge X-ray Absorption Near-Edge Structure (XANES) Spectroscopy.

Phosphorus (P) is an essential element for life on Earth, with an important and oftentimes unaccounted organic biogeochemical component. Current methods for the quantification of different organic P compounds in environmental samples (e.g., soils, sediments) are based on extraction techniques and often associated with incomplete P recovery or sample changes. In this study, we present a protocol for the quantification of different organic and inorganic P species in soils using synchrotron-based X-ray absorption near-edge structure (XANES) spectroscopy at the P L2,3-edge. Its accuracy and precision was evaluated by analyzing 40 standard mixtures composed of seven different inorganic and organic P compounds (with a mean of R2 = 0.85). In addition, we quantified the P species of two soils and two agro-industrial byproducts using P L2,3-edge XANES spectroscopy and the results were compared with those obtained by P K-edge XANES or 31P NMR spectroscopy. Using the P L2,3-edge, we identified different organic Pspecies, including those not identified by the common P K-edge XANES. However, there is a consistent underestimation of organic polyphosphates. Overall, the application of P L2,3-edge XANES provides a higher level of information than by P K-edge XANES, although the ubiquitous use of this novel methodology is still limited to samples with a phosphorus content above 3 mg g-1.

Anderson-type polyoxometalate-based hybrid with high flame retardant efficiency for the preparation of multifunctional epoxy resin nanocomposites

Transition metal oxides based catalytic carbonization have been proved to be a promising way to enhance polymer flame retardancy, but finding better way to introduce organic phosphorus and transition metal oxide hybrids into polymer matrix to form nanocomposites is still a great challenge. In this work, an organic phosphorus and metal oxide hybrid compound named P–MnMo6 was prepared through combining 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) with polyoxometalate (POM). The as-prepared P–MnMo6 had a center of [MnMo6O18]3- and was used as the precursor of transition metal oxides to improve the flame retardancy of epoxy resin (EP). With the aid of the organic modification, the addition of P–MnMo6 not only maintained the transparency of EP but also enhanced the dynamic mechanical properties. Notably, the thermogravimetric analysis showed that the char yield of EP/P–MnMo6 composite increased significantly. Besides, epoxy with 8 wt% addition of P–MnMo6 passed the vertical burning grade (UL-94) V-0 rating with the limiting oxygen index (LOI) value of 30.4%. Cone calorimeter test indicated the peak heat release rate of EP/P–MnMo6-4 decreased by 41%. Meanwhile, smoke products and CO were greatly suppressed. In addition, the potential flame retardancy mechanism of P–MnMo6 in epoxy matrix was proposed.

Analysis of the Degree Of Implementation of Environmental Measures in the Sphere of Water Protection Against Anthropogenic Pollution According To The Strategy Of The State Environmental Policy of Ukraine for the Period up to 2020

Purpose. The article provides an analysis of the degree of implementation of the tasks and activities of the Strategy of the State Environmental Policy of Ukraine for the period until 2020 in relation to Goal 2 to improve the environmental situation and increase the level of environmental safety in the field of water resources protection through the reconstruction of existing and construction of new urban treatment facilities in order to reduce to 2020 years of the level of anthropogenic pollution. Methods. The system analysis was carried out on the basis of information, statistical and calculated data on the national reports of the Ministry of Regional Development. Results It has been established that the planned environmental protection measures in the field of water resources protection, especially in the area of water disposal, are often not implemented due to the lack of funding at the level of the state budget and national target programs. However, in recent years, a positive trend has been noted to improve the situation in the field of repair, reconstruction, modernization and construction of systems of communal treatment facilities. It has been determined that the dynamics of changes in the volume (in percentage) of insufficiently treated wastewater discharged into water bodies tends to decrease. Conclusions. On the basis of data processing, the fulfillment of Goal 2 was confirmed in full, namely, the reconstruction of existing and construction of new urban wastewater treatment plants was carried out in order to reduce the level of water pollution by pollutants (primarily organic substances, nitrogen and phosphorus compounds) by 15 percent by 2020, and also reduced by 2020 by 20 percent (to the base year) the discharge of insufficiently treated wastewater.

Chemical and microbiological characteristics of the agrolandscape Zeya-Bureya plain small river

The article discusses the results of hydrochemical and microbiological studies of the waters of the small river Arguzikha, the left-bank tributary of the Amur River. The natural landscapes of the Zeya-Bureya plain, along the territory of which a small river flows, are transformed into agrolandscapes. Organic matter, nitrogen and phosphorus compounds accumulated in the waters of the Arguzikha river. The number of heterotrophic bacteria, the main function of which is the destruction of organic matter, in the summer reached 75 thousand cells / ml, which corresponded to the dirty water quality class. The content of nitrogen compounds in water and the number of ammonium-oxidizing bacteria experienced seasonal dynamics. The obtained results of the study of hydrochemical and microbiological indicators of aquatic ecosystems of the Zeya-Bureya plain are the basis for further study of the technogenic load on small rivers of the agrolandscape.

TiO2/Cu2O nanoparticle-catalyzed direct C(sp)–P bond formation via aerobic oxidative coupling in air and visible light

The synthesis of organophosphorus compounds is one of the important goals in organic chemistry. Among these compounds, alkynylphosphonates are significantly utilized as the main precursors for the synthesis of biologically active molecules in medicinal chemistry and have attracted extensive interest in the past few decades. Although few efforts have been made towards the direct and atom-economical synthesis of alkynylphosphonates, efforts towards the utilization of visible light as a green and renewable energy source have not been made to date. Here, we have promoted a strategy to construct a type of nano metal oxide composite photocatalyst (Cu2O decorated on TiO2) for the synthesis of alkynylphosphonates via direct C-P bond formation between terminal alkyne and H-phosphonate under visible light irradiation. In this p-n heterojunction photocatalyst, Cu2O acted as a visible-light absorber; moreover, the CB (conduction band) of TiO2 was favorable for accepting a photogenerated electron, and the generated electron hole (e-/h+) pair could initiate the reaction. The present study can provide a new way for the synthesis of this important class of phosphorus organic compounds.

N-heterocyclic compounds of phosphorus based ON N,N-disubstituted 9,10-phenanthrenediimines

N‑heterocyclic phospholes based on N,N-disubstituted 9,10-phenanthrenediimines were synthesized. Dimeric 1,3,2-diazaphospholes were obtained by reduction of 2-bromo diazaphospholes. In case phenanthrediimine with the most sterically hindrance, diphosphole can dissociate into phosphorus-centered radicals at record low temperatures (220 K) for this class. This behavior will allow the synthesis of new metal complexes and phosphorus-organic compounds under mild conditions.

Highly efficient thermal oxidation and cross-linking reaction of catechol functionalized polyacrylonitrile copolymer composites for halogen-free flame retardant

There have been major efforts to make polyacrylonitrile (PAN) flame retardant using halogens, heavy metals, transition metals, and phosphorus-organic compounds. These retardants may reduce the risk of fire, but they also involve high cost, toxicity, and related ecological issues. In an effort to mitigate some of these negative factors, we herein report the development of a green flame-retardant PAN based on bio-inspired dopamine methacrylamide (DMA) co-monomer. This polymer was synthesized through free radical polymerization of AN and acetonide-protected dopamine methacrylamide (ADMA), followed by deprotection of ADMA. Systematic investigation of the structural evolution of P(AN-co-DMA) confirmed that DMA provides a kinetic advantage for initiating the cyclization of PAN at significantly lower temperatures (209 °C) as well as for controlling effectively the amount of heat generated. Moreover, the effective radical scavenging capability of DMA, and the formation of a carbonaceous layer on the polymer surface, greatly improved the flame-retardant performance of PAN, without the use of conventional additives. This resulted in low heat-release capacity (HRC) and high limiting oxygen index (LOI) values of 58 Jg–1 K−1 and 37% (superior to those values of Nomex®), respectively. The thermal oxidative stabilization (TOS) process and flame retarding properties of PAN/GO composites were further investigated. TOS process and flame retarding mechanism were found to be influenced by ionic interaction and hydrogen bonding between polymer and nanomaterial. This work opens up a facile and sustainable methodology for the design of environmentally friendly and high-performance flame retardants and composites.