31P NMR Spectra Research Articles

Phosphorus-Nitrogen Compounds: Part 76. Design and Syntheses of Dispiro- and Trispiro(N/N)cyclotriphosphazenes: Conformational and Structural Analyses, Chirality, Electrochemical, Dye-Sensitized Solar Cells, and Bioactivity Studies.

The reactions of monospirocyclotriphosphazenes (1 and 2) with N-methyl-1,3-diaminopropane gave unsymmetrical cis-(3 and 5) and trans-(4 and 6) dispirocyclotriphosphazenes. Trans-cis-trans (tct) (7 and 11), cis-cis-cis (ccc) (8 and 12), trans-trans-cis (ttc) (9 and 13), and cis-trans-trans (ctt) (14) trispirocyclotriphosphazenes were obtained from the reactions of 3 and 5 and 4 and 6 with N-methyl-1,3-diaminopropane. cis-Dispirocyclotriphosphazenes (3 and 5) exist as "pseudomesoracemates", while trans-dispirocyclotriphosphazenes (4 and 6) are in "racemates". The existences of cis-3 and trans-4 as "pseudomesoracemate" and "racemate" were confirmed by 31P NMR spectra recorded by the addition of "chiral solvating agent (CSA)". X-ray crystallography proved that the absolute configurations of each enantiomer of cis-5 and trans-6 are SS' and RS'. Trispirocyclotriphosphazenes tct, ttc, ccc, and ctt exist as racemates, pseudomesoracemate, and meso forms. Furthermore, Hirshfeld surface analysis of the crystal structures of cis-5 and trans-6 revealed that the most significant contribution to crystal packing comes from H···H (58.2 and 57.6%, respectively). An oxidation-reduction wave was detected in the reversible cyclic voltammograms of the phosphazenes. The highest power conversion efficiency in dye-sensitized solar cell studies was obtained with cis-5. Additionally, trans-6 exhibited the lowest minimal inhibitory concentration value (78.1 μM) against Candida tropicalis, and it was observed to cleave pBR322 plasmid DNA.

Mechanochemical Polyoxometalate Super-Reduction with Lithium Metal.

In this first systematic investigation of mechanochemical polyoxometalate (POM) reduction, (TBA)3[PMo12O40] was reacted with n equiv of lithium metal (n = 1-24) to generate PMo12/n products which were shown to be mixtures of electron-rich PMo12Lix species. FTIR analysis revealed the lengthening/weakening of terminal Mo═O bonds with increasing levels of reduction, while EXAFS spectra indicated the onset of Mo-Mo bond formation at n ∼ 8 and a significant structural change at n > 12. Successive MoVI reductions were monitored by XANES and XPS, and at n = 24, results were consistent with the formation of at least one MoIV-MoIV bonded {MoIV3} triad together with MoV. Upon dissolution, the PMo12Lix species present in the solid PMo12/n products undergo electron exchange and single-peak 31P NMR spectra were observed for n = 1-12. For n ≥ 16, changes in solid state and solution 31P NMR spectra coincided with the emergence of features in the UV-vis spectra associated with MoV-MoV and {MoIV3} bonding in an ε-Keggin structure. Bonding between {Li(NCMe)}+ and 2-electron-reduced PMo12 in (TBA)4[PMo12O40{Li(NCMe)}] suggests that super-reduction gives rise to more extensive Li-O bonding that ultimately causes lithium-oxide-promoted TBA cation decomposition and POM degradation, which might explain the appearance of XPS peaks for Mo2C at n ≥ 16. This work has revealed some of the complex, unexplored chemistry of super-reduced POMs and establishes a new, solvent-free approach in the search for a better fundamental understanding of the electronic properties and reactivity of electron-rich nanoscale metal oxides.

Novel tryptamine decorated cyclotriphosphazene derived Schiff base compounds: Synthesis, characterization and molecular docking studies

In this study, new cyclotriphosphazene derivative Schiff base compounds including tryptamine units were synthesized for the first time. The structures of all compounds (2–9) were characterized by FT-IR, mass, 1H and 31P NMR spectra. In addition, the solid-state structure and geometry of salicylaldehyde-substituted cyclotriphosphazene compound 6 using as the precursor were determined by single-crystal X-ray analysis. Molecular docking studies were performed to elucidate the interactions between target molecules and the compounds under investigation, aiming to assess their therapeutic potential and predict their biological activities. Screening results revealed significant interactions between the compounds and key protein structures, including IGFBP, PI3K, LE, JAK3, and PTP-2, which are involved in critical cellular processes. Furthermore, in silico evaluations were conducted to analyze the physicochemical properties, pharmacokinetics, and toxicological profiles of synthesized compounds.

ATP, the 31P Spectral Modulus, and Metabolism.

Adenosine triphosphate (ATP) has a high intracellular millimolar concentration (ca. 2.4 mM) throughout the phylogenetic spectrum of eukaryotes, archaea, and prokaryotes. In addition, the function of ATP as a hydrotrope in the prevention of protein aggregation and maintenance of protein solubilization is essential to cellular, tissue, and organ homeostasis. The 31P spectral modulus (PSM) is a measure of the health status of cell, tissue, and organ systems, as well as of ATP, and it is based on in vivo 31P nuclear magnetic resonance (31P NMR) spectra. The PSM is calculated by dividing the area of the 31P NMR integral curve representing the high-energy phosphates by that of the low-energy phosphates. Unlike the difficulties encountered in measuring organophosphates such as ATP or any other phosphorylated metabolites in a conventional 31P NMR spectrum or in processed tissue samples, in vivo PSM measurements are possible with NMR surface-coil technology. The PSM does not rely on the resolution of individual metabolite signals but uses the total area derived from each of the NMR integral curves of the above-described spectral regions. Calculation is based on a simple ratio of the high- and low-energy phosphate bands, which are conveniently arranged in the high- and low-field portions of the 31P NMR spectrum. In practice, there is essentially no signal overlap between these two regions, with the dividing point being ca. -3 δ. ATP is the principal contributor to the maintenance of an elevated PSM that is typically observed in healthy systems. The purpose of this study is to demonstrate that (1) in general, the higher the metabolic activity, the higher the 31P spectral modulus, and (2) the modulus calculation does not require highly resolved 31P spectral signals and thus can even be used with reduced signal-to-noise spectra such as those detected as a result of in vivo analyses or those that may be obtained during a clinical MRI examination. With increasing metabolic stress or maturation of metabolic disease in cells, tissues, or organ systems, the PSM index declines; alternatively, with decreasing stress or resolution of disease states, the PSM increases. The PSM can serve to monitor normal homeostasis as a diagnostic tool and may be used to monitor disease processes with and without interventional treatment.

Regulatory mechanisms of phosphorylation in ovalbumin self-assembly for aggregates formation: Insights into size, structure, and morphology

In this study, the impact of different phosphorylation degrees on ovalbumin (OVA) assemblies was investigated by introducing negatively charged phosphorylated groups as driving forces at pH 9.0 and 85 °C for 2, 4, 6, 10, and 12 h to examine their turbidity, zeta-potential, and average particle size during phosphorylation-mediated aggregation. The presence of phosphate groups in the aggregates was confirmed by 31P NMR and FTIR spectra. The aggregation process, including amyloid formation, was analyzed by evaluating active thiol groups, intrinsic fluorescence spectra, surface hydrophobicity, circular dichroism, and thioflavin T (THT) fluorescence. TEM and small-angle scattering analysis of the morphological evolution of the self-assembly process over time revealed a structural progression from flexible to longer and thicker flexible fibrils, with the formation of shorter, more rigid semiflexible aggregates after 10h of phosphorylation. When phosphorylated for 12 h, the OVA aggregates exhibited a compact core primarily composed of cross β-structures and surrounded by loosely packed protein segments with random coil structures. Overall, this study highlighted the enhancement of OVA self-assembly by phosphorylation, where electrostatic and hydrophobic interactions play pivotal roles in regulating the formation of protein self-assembly aggregates.

On the Structure and Role of Avian Eggshells: A 31P, 1H, and 13C Solid-State NMR Study.

The eggshell is a composite and highly ordered structure formed by biomineralization. Besides other functions, it has a vital and intricate role in the protection of an embryo from various potentially harsh environmental conditions. Solid-state nuclear magnetic resonance (SSNMR) has been used for detailed structural investigations of the chicken, tinamou, and flamingo eggshell materials. 31P NMR spectra reveal that hydroxyapatite and β-tricalcium phosphate in the ratio 3:2 represent major constituents of phosphate species in the eggshells. All three eggshells exhibit similar spectra, except for the line widths, which implies different structural order of phosphate species in the chicken, tinamou, and flamingo eggshells. 1H NMR spectra for these materials are comparable, differentiating overlapped peaks in three spectral regions at around 7, 4-5, and 1-2 ppm. These spectral regions have been attributed to protons from NH or CaHCO3, water, and possibly isolated monomeric water molecules or hydroxyl groups in calcium-deficient hydroxyapatite. 1H-13C CP MAS NMR revealed the presence of organic matter in the form of lipids and proteins. Two overlapped resonances in the carbonyl region at around 173 and 169 ppm are assigned to the carbonyls of the peptide bonds and the bicarbonate unit in calcite, respectively. Fourier-transform infrared spectroscopy (FTIR) spectra confirmed the presence of structural units detected in the NMR spectra.

Synthesis, DFT investigation, ADME-T properties, molecular docking and molecular dynamics simulation of new α-aminophosphonate inhibitor targeting Mpro and RdRp enzymes in SARS-CoV-2

A specific α-aminophosphonate molecule, namely diethyl (phenyl (4-pyridinylamino) methyl) phosphonate (α-DAP), as a potential SARS-CoV-2 inhibitor, has been synthesized via a Kabachnick-Fields reaction, a three-component, dalfampridine, benzenecarbaldehyde and triethoxyphosphine, and its molecular structure was confirmed by spectroscopic and physicochemical methods such FT-IR, UV–vis, melting point, 1H NMR, 13C NMR and 31P NMR spectra. The Density Functional Theory (DFT) at the B3LYP/6–31 G (d, p) level was used to calculate the optimized structure, reactivity, stability of the target molecule. In this context, several characteristics have been calculated and the obtained theoretical results are in good agreement with the experimental ones. Also, predicted ADME-T were performed and the obtained parameters indicated that the compound under investigation should have good oral bioavailability. In addition, the molecular docking has been used, further, the compound showed high potential docking with SARS-CoV-2 major protease (Mpro) and RNA dependent RNA polymerase (RdRp). Finally, the molecular dynamics simulation demonstrated the stability of the protein-ligand interaction and offered insights into the specific amino acid residues participating in the binding process.

Bis(acyl)phosphide Complexes of U(III)/U(IV): A Case of a Hidden Redox-Active Ligand.

The recently reported tris(bis(2,4,6-triisopropylbenzoyl)-phosphide)uranium (UIII(trippBAP)3, 2) complex (Inorg. Chem. 2022, 61 (32), 12508-12517) demonstrated a silent 31P NMR spectrum. This complex was described as a U(III) complex with an organic radical ligand fragment. Moreover, the EPR spectrum of 2 was indicative of an organic radical in the ligand framework complexed to uranium, in contrast to that of UIV(mesBAP)4, 1. Herein, with the help of relativistic density functional theory (DFT) calculations, the electronic structures of 1, 2, and U(mesBAP)3 (4) are examined in an effort to understand the unusual 31P NMR spectrum of 2. Results indicate the reduction of the carbonyl bonds and delocalization of the electrons over the ligands, indicative of U → L backbonding. Additionally, the reduced acyl carbons are found to exist as ketyl radicals [O═C• -] that are responsible for the silent 31P NMR spectra of 2. These findings demonstrate the redox noninnocent nature of BAP- in 2 and 4, causing uranium to exist in a formal oxidation state of +4.

A practical dinucleotide phosphoramidite chemistry for de novo DNA synthesis via block coupling

With the development of synthetic biology, the demand for high-quality long oligonucleotides is increasing. The use of dinucleotide phosphoramidites (dimer amidites) will reduce half of the steps required in the stepwise monomer condensation, which is expected to lead to the high-quality synthesis of oligonucleotides. Herein, we report a convenient, unified procedure for the sustainable preparation of fully protected dimer amidites bearing a methyl phosphate and a β-cyanoethyl phosphoramidite. Key precursors of those amidites—dimers containing a 3′-hydroxyl group—have been prepared in high yield using a one-pot, scalable approach. The structures of all 16 dimer amidites and corresponding 3ʹ-hydroxyl dimers were confirmed by HPLC-MS and 31P NMR spectra. With these dimer amidites, modification of the standard method for automated solid-phase oligonucleotide synthesis enables high-yield block couplings. Oligonucleotides synthesized following this method are of sufficient quality to assemble gene-length DNA fragments. As a consequence, we develop a practical dinucleotide phosphoramidite chemistry for de novo DNA synthesis.

Small molecules dominate organic phosphorus in NaOH-EDTA extracts of soils as determined by 31P NMR

Understanding the composition of organic phosphorus (P) in soils is relevant to various disciplines, from agricultural sciences to ecology. Despite past efforts, the precise nature of soil organic P remains an enigma, especially that of the orthophosphate monoesters, which dominate 31P NMR spectra of NaOH-EDTA extracts of soils worldwide. The monoester region often exhibits an unidentified, broad background believed to represent high molecular weight (MW) P. We investigated this monoester background using 1D 31P NMR and 2D 1H31P NMR, as well as 31P transverse relaxation (T2) measurements to calculate its intrinsic linewidth and relate it to MW. Analyzing seven soils from different ecosystems, we observed linewidths of 0.5 to 3 Hz for resolved monoester signals and the background, indicating that it consists of many, possibly >100, sharp signals associated with small (<1.5 kDa) organic P molecules. This result was further supported by 2D 1H31P NMR spectra revealing signals not resolved in the 1D spectra. Our findings align with 31P NMR studies detecting background signals in soil-free samples and modern evidence that alkali-soluble soil organic matter consists of self-assemblies of small organic compounds mimicking large molecules.

Multiscale structure analysis reveals changes in the structure of casein micelles treated with direct-steam-infusion UHT

Direct-steam-infusion ultra-high temperature (dUHT) technology has been paid much attention to in recent years because of its short heating time, which helps retain more nutritional ingredients and extend shelf life of dairy products. However, protein instability is an urgent problem for dUHT milk to solve. As the main component of protein, it is unclear whether and what structural changes casein micelles (CMs) undergo after dUHT treatment. In this study, CM dispersions were treated with dUHT technology (140 °C/3 s, 145 °C/3 s, 150 °C/3 s, 155 °C/3 s, and 157 °C/0.116 s), and unheated sample was taken as the control. As the temperature increased, hydrodynamic diameter of the CMs reduced from 190 nm to 156 nm, zeta potential did not change significantly, and turbidity decreased significantly. After dUHT, contents of casein, calcium, and phosphorus in the serum phase increased. Furthermore, dUHT treatment would lead to disruption of intermolecular hydrogen bonds, rearrangement of secondary structures, and unfolding of CM. The 31P NMR spectra demonstrated that colloidal calcium phosphate solubilized and electrostatic repulsion within micelles increased with dUHT treatments. Further analysis of molecular structure of CMs using small-angle X-ray scattering and a cryo-transmission electron microscope found that after dUHT treatment, CMs dissociated in the form of casein clusters (20–40 nm) and became loose and porous in structure. In conclusion, dUHT treatment destroyed the calcium bridges and increased electrostatic repulsion inside micelles, leading to dissociation of casein clusters and a smaller, looser, and more porous structure of the CMs.

The Flame Retardant and Mechanical Properties of the Epoxy Modified by an Efficient DOPO-Based Flame Retardant.

Currently, the mechanical performance reduction caused by excessive phosphorus content in the halogen-free flame-retardant EP has been an obstacle to its extensive application. This study presents the effective synthesis of a novel flame-retardant BDD with great efficiency, achieving an optimum phosphorus level of merely 0.25 wt %. The structure of BDD was verified by FTIR, 1H NMR, 31P NMR and XPS spectra. To investigate the flame-retardant properties of BDD, several EPs with various phosphorus levels were synthesized. The addition of phosphorus to the EP significantly increases its LOI value from 25.8% to 33.4% at a phosphorus level of 0.25 wt%. Additionally, the resin achieves a V-0 grade in the UL 94 test. The P-HRR and THR of the modified resin measured by the cone calorimeter are also significantly reduced. At the same time, the addition of a modest quantity of BDD has a minimal impact on the mechanical properties of epoxy resin. This study shows that the removal of hydroxyl groups significantly enhances the fire resistance of phosphate-based flame retardants, thereby providing a novel approach to synthesizing efficient flame retardants.

Consecutive extraction of neutral and polar lipids from skipjack tuna (Katsuwonus pelamis) byproducts using supercritical carbon dioxide

This study aimed at the consecutive extraction of neutral and polar lipids (phospholipids) from skipjack tuna (Katsuwonus pelamis) byproducts using an entrainer (ethanol) combination of green extraction system supercritical carbon dioxide. The head, viscera, and skin of tuna fish were subjected to extraction. The highest proportion of lipids was obtained from the skin (31.18% ± 0.59%), and the net phospholipids were obtained from the head (3.24%). Oils and phospholipids are rich in omega-3 and omega-6 polyunsaturated fatty acids. Phospholipids were identified and their composition was analyzed based on 31P NMR spectra. Three important classes of phospholipids are phosphatidylcholines (PC), phosphatidylethanolamine (PE), and lysophosphatidylcholine (LPC). Tocopherol is the major vitamin present in oils and phospholipids from K. pelamis byproducts. Thermogravimetric analysis and differential thermogravimetric analysis confirmed that the extracted neutral and polar lipids are stable at cooking temperatures and can be used in various industries.

A wheel-shaped Zr-substituted phosphotungstate [{Zr(C2O4)2}3 (PO4)(P6W39O150)]39- with tunable proton conduction properties.

A wheel-shaped Zr-substituted phosphotungstate, [N(CH3)4]2K16Na10.5H10.5[{Zr(C2O4)2}3(PO4)(P6W39O150)]·45H2O (1), was synthesised from a hexavacant Dawson-type precursor [H2P2W12O48]12-via a conventional solution method. Compound 1 features a wheel-shaped polyanion comprising an annular [P6W39O150]36- cluster supported by a turbine-shaped [{Zr(C2O4)2}3(PO4)]3- fragment, with three oxalate groups covalently anchored to W atoms. Compound 1 was systematically characterized by IR, UV, PXRD, TGA and 31P NMR spectra. The 31P NMR spectra over time were monitored to verify the stability of 1 in aqueous solution. This compound possesses remarkable proton conductive behavior with a high conductivity of 1.18 × 10-2 S cm-1 at 368 K.

Terminal {Ni(II)-SH} complex promoted anaerobic catalytic sulfur atom transfer reaction: implication to the sulfide oxidase function of Cu/Zn-superoxide dismutase.

In mitochondria, the detoxification of molar excess H2S as polysulfide proceeded via an oxidation process promoted by Cu/Zn containing superoxide dismutase (SOD1) enzyme, which has been very recently reported as the alternative enzyme for cytosolic H2S oxidation. Herein, we present Ni(II) complexes bearing the terminal SH group as a synthetic functional analogue for the sulfide oxidase function of SOD1. Synthesis, crystal structure and complete spectroscopic characterization of two sets of complexes, [NiLOMe/tBu(PPh3)] (2OMe/tBu) and tetraethyl salt of [NiLOMe/tBu(SH)]-1 (3OMe/tBu), were described (LOMe = (E)-2-methoxy-6-(((2-sulfidophenyl)imino)methyl)phenolate and LtBu = (E)-2,4-di-tert-butyl-6-(((2-sulfidophenyl)imino)methyl)phenolate). Under anaerobic conditions, 3OMe/tBu responded to a catalytic sulfur atom transfer (SAT) reaction with PPh3 to produce SPPh3. The SAT reaction was analyzed using detailed studies of 1H and 31P NMR spectra. Finally, the SAT reactivity pattern was compared with the same in the native enzyme of SOD1.

Механосинтез полимерных α-аминофосфонатов

Kabachnik–Fields reaction is widely used to obtain α-aminophosphonates, including polymeric ones. In addition, methods for the mechanosynthesis of α-aminophosphonates under mechanosyn-thesis conditions are being developed. The article examined methods for the preparation of aryl-substituted polymeric α-aminophosphonates by reacting isomeric diaminobiphenyls, terephthalic aldehyde and diethylphosphonate in the absence of a solvent in a ball mill. As a result, polymeric α-aminophosphonates 4 were obtained. The structure of the products was established on the basis of 1H, 31P and IR NMR spectra. In the 1H NMR spectrum, it should be noted the presence of charac-teristic signals of the protons of aromatic fragments in the form of multiplets at 8.62, 8.07 and 7.54 ppm, signals of the proton at the sp3-hybridized carbon atom in the form of a broadened singlet at 3.75 ppm, as well as a signal of the protons of the group OСH2CH3 as a multiplet at 4.14 ppm. and a multiplet at 1.20 ppm. In the 31P spectrum there was the presence of a phosphorus signal at 22.96 ppm. Absorption bands at 1161 cm–1 (P=O), 1051 cm–1 (P-C-O), 2957 cm–1 (OCH3) and 3445 cm–1 (NH amide fragment) were observed in the IR spectra. Additionally, the possibility of post-modification of polyvinyl chloride (PVC) with fragments of α-aminophosphonates was investigat-ed by reacting the former with 2-aminothiophenol, benzoaldehyde and diethylphosphonate in the absence of a solvent in a ball mill, as well as by reacting with 2-aminothiophenol, terephthalic aldehyde and diethylphosphonate under similar conditions. Thus, a possibility of mechanosynthesis of α-aminophosphonates was demonstrated, as well as the possibility for the post-modification of PVC with fragments of α-aminophosphonates.

Hyphenation of lipophilic ruthenium(II)-diphosphine core with 5-fluorouracil: an effective metallodrug against glioblastoma brain cancer cells.

Glioblastoma multiforme (GBM) is the most common highly aggressive malignant brain tumor, with a very limited chance for survival post-diagnosis and post-treatment. Despite significant advancement in GBM genomics implicated in molecularly targeted chemotherapies, the prognosis remains poor and requires new drug discovery approaches. We used fluoropyrimidine 5-fluorouracil (5-FU), an antimetabolite anticancer drug conjugated or 'caged' within a lipophilic Ru(II)-diphosphine (dppe) core formulated as [RuII(dppe)2(5-FU)]PF6 (Ru-DPPE-5FU), where dppe = 1,2-bis(diphenylphosphino)ethane, and evaluated its in vitro cytotoxicity in depth with aggressive GBM cells (LN229). The hydrophilic nature of 5-FU limits its passage through the blood-brain barrier (BBB), which prevents its effective accumulation and efficacy for GBM tumors. Herein, we attempted to modulate the lipophilicity of 5-FU by inserting it within a well-designed lipophilic {Ru(dppe)2}-core with anticipated higher efficiency towards GBM. The physicochemical properties of [RuII(dppe)2(5-FU)]PF6 (Ru-DPPE-5FU) were studied using various spectroscopic and analytical techniques. The molecular structure was determined using X-ray crystallography, showing a distorted {RuP4NO} octahedral geometry with bidentate (N, O) binding of 5-FU and its aromatization in the Ru(II)-bound form. The 31P-NMR spectra of Ru-DPPE-5FU showed four closely spaced distinct 31P-signals, indicating four unique chemical environments around P, and the strong coupling constants between them make it a second-order spectrum. The RuII/RuIII redox potential in Ru-DPPE-5FU shifted by ∼0.91 V towards the anodic region as compared to its precursor complex cis-[Ru(dppe)2Cl2] (Ru-DPPE-Cl). DFT-based theoretical calculations have been performed to correlate the experimental electronic absorption spectra and redox behaviours of the complexes. The electrostatic potential (ESP) plots indicate the delocalization of the charge density on the O-/F-atom from the 5-FU ligand towards Ru(II) upon its complexation. The antioxidant properties of all the compounds were quantified by a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The hyphenation of the 5-fluorouracil (5-FU) ligand to the lipophilic {Ru(dppe)2}-core endowed lipophilicity to Ru-DPPE-5FU with higher in vitro cytotoxicity (IC50 = 2.37 μM) against the LN229 GBM cells as compared to the hydrophilic 5-FU, suggesting efficient cellular uptake. Further biological assays indicated that the complex is highly potent in inhibiting significant proliferation and spheroid formation and restricting the migratory potentials of the GBM cells. Increased caspase 3/7 activity and the presence of apoptotic bodies at the center of 3-D GBM spheroids as revealed by AO/EB dual staining indicated a deeper penetration of the lipophilic complex. The Ru-DPPE-5FU complex displayed lower cytotoxicity in HaCaT normal cells (IC50 = 7.27 μM) in comparison to LN229 cancer cells with a selectivity index (S.I.) of ≥3. Overall, the synergism and caging of 5-FU within the hydrophobic {Ru(dppe)2}-core improves the pharmacokinetic profile of Ru-DPPE-5FU as a potent anticancer agent for glioblastoma.

Influence of sulfur ions on the glass-forming ability and structure of silicate-phosphate glasses

The aim of the study was to analyze the structure of two groups of glasses: first sulfur-free from the SiO2-P2O5-K2O-MgO system and second sulfur-containing from the SiO2-P2O5-K2O-MgO-SO3 system with various network formers content in the form of P2O5 and SiO2. The sulfur speciation in the sulfur-bearing glasses was also determined. The sulfur-containing glasses were obtained under reducing conditions. The bulk composition of the glasses was confirmed by X-Ray Fluorescence Spectroscopy. The amorphous nature of the samples was verified using XRD analysis. The structure of the materials was studied with the 29Si and 31P MAS NMR and XAS spectroscopic techniques. It was found that the addition of sulfur increased the ability of glasses with higher amounts of P2O5 to form. XAS spectra demonstrate that S-bearing glasses contain sulfur in the reduced form as S2-. The 31P and 29Si MAS NMR spectra did not detect P-S and Si-S linkages.

Land reclamation increased organic P fractions and phosphatase activities, and strengthened the co-occurrence networks of phoD community in calcareous soils

Organic phosphorus (Po) is an important constituent of P pool. Soil phoD community is primarily involved Po transformation. However, influences of agriculturally-driven land-use change on different Po fractions, phosphatase activities and phoD community are largely unknown. Here, an investigation was carried out containing three treatments: vegetable field (VF), cropland (CF) and uncultivated land (UL). Various Po fractions were measured by Hedley’s sequential extraction and 31P-NMR methods. The activities of alkaline phosphomonoesterase (ALP), acid phosphomonoesterase (ACP), phosphodiesterase activity (PD) and phytase were assayed; the abundance, and diversity of phoD community and its co-occurrence networks were analyzed. Compared with the UL treatment, soil total organic P (total-Po) in the VF and CF treatments significantly increased by 75.9% and 53.0%, respectively, mainly attributed to the increases in NaHCO3-Po, NaOH-Po and C.HCl-Po. 31P-NMR spectra showed that, when land was reclaimed from uncultivated land into agriculture fields (i.e., VF and CF), myo-inositol hexaphosphate (myo-IHP), α-glycerophosphate (α-glyc) and β-glycerophosphate (β-glyc) were increased by 9.5, 3.9 and 2.0 times, respectively. The activities of ACP, ALP and PD in the VF and CF treatments were higher than in the UL treatment. The α-diversity of phoD community was also significantly increased by land reclamation. Moreover, the linkage between soil Po and Po-cycling-related biological parameters (ACP, ALP and PD and phoD community) was more pronounced by NaHCO3-Po and NaOH-Po than the Po fractions measured by 31P-NMR method. Topological parameters (edges, node degree, and betweenness centrality) of phoD community’s network in the VF and CF networks were higher than in the UL network, implying that land reclamation favored to construct a more cooperative network of phoD community. Collectively, our findings demonstrated that when uncultivated land was converted to cropland, soil Po was notably increased, and phoD community’s co-occurrence network was also strengthened. The outcomes of this study emphasize that when land was reclaimed from nature (uncultivated land) into agriculture fields, the fertilization strategy of organic combined with chemical fertilizers application was beneficial for improving P fertility and assembling organic P-cycling related community.

Функциональный состав и структурные особенности лигнинов высших растений

NMR spectroscopy is one of the effective methods for the study of plant raw materials, which makes it possible to identify differences in the structure and functional composition of lignins of various types of plant biomass. However, there are a number of limitations in the use of this method – in particular, the registration of NMR spectra at some nuclei (13C, 31P, etc.) usually requires considerable amount of time. This article proposes an approach to reduce the recording time of 31P NMR spectra by a factor of 17 without losing the quality of the result. With the help of this method and with the use of optimized experimental parameters, the functional group analysis of lignins of some softwood and hardwood species and herbaceous plants distributed in the European North of the Russian Federation was carried out. The types of structural units and their characteristic interstructural relationships per 100 phenylpropane units were determined by HSQC NMR. Differences in the functional composition and features of the structural organization of lignins were identified depending on the family to which the plant belongs. On the basis of the obtained array of experimental data the strategies of processing of specific types of plant raw materials were proposed. For example, lignins of the Birch and Beech families showed the largest number of β-aryl ether fragments with a free hydroxyl group in the α-position, which indicates the greater reactivity of these lignins. Accordingly, representatives of these families are priority raw materials in the development of lignin processing methods. At the same time, the structure of lignins of representatives of the Beech family proved to be the most resistant to hydrolytic degradation, which is important for lignin-directed bioprocessing concepts. For citation: Sypalova Yu.A., Shestakov S.L., Kozhevnikov A.Yu. Functional Composition and Structural Features of Higher Plant Lignins. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 5, pp. 164–183. (In Russ.). https://doi.org/10.37482/0536-1036-2023-5-164-183