scholarly journals Low-coordinate organophosphorus compounds: some stereochemical considerations

2019 ◽  
Vol 91 (1) ◽  
pp. 77-85
Author(s):  
Masaaki Yoshifuji
Keyword(s):  
Chemical Property ◽  
Organophosphorus Compounds ◽  
Palladium Complexes ◽  
Chiral Hplc ◽  
Inversion Process ◽  
Chiral Amine ◽  
Rotational Isomers ◽  
Hplc Column ◽  
Sterically Demanding ◽  
Physical And Chemical

Abstract Utilizing 2,4,6-tri-tert-butylphenyl as a sterically demanding group (abbreviated as Mes*), we have been successful in isolation, characterization, physical and chemical property investigation of low-coordinate organophosphorus compounds such as those carrying P=P and P=C bonds. Diphosphene, 1-phosphaethene, 1,3-diphosphaallene, 1-phosphaallene, and 3,4-diphosphinidenecyclobutenes are discussed in terms of stereochemistry including E/Z isomerization around P=P or P=C bond and R/S resolution of rotational isomers around crowded P–C bonds with chiral HPLC column. (π-Allyl)palladium complexes ligated with 3,4-diphosphinidenecyclobutene are useful in such catalytic organic reactions as the Tsuji-Trost reaction by which from a chiral s-alcohol, the corresponding chiral amine is obtained with retention of chirality suggesting double inversion process.

Enzymes and Their Forms Used in Detection of Organophosphorus Compounds

2021 ◽  
pp. 22-41
Keyword(s):  
Organophosphorus Compounds ◽  
Degradation Products ◽  
Rapid Development ◽  
Hydrolytic Enzymes ◽  
Immobilized Enzymes ◽  
Amino Acid Sequences ◽  
Practical Implementation ◽  
Scientific Results ◽  
Physical And Chemical

Еnzymes are able to effectively interact with various organophosphorus compounds (OPC), entering into (bio)chemical reactions with them. Changes in the initial activity of enzymes as a result of their inhibition by OPC, the formation of OPC degradation products under the action of hydrolytic enzymes, etc. can be determined using different physical and chemical methods and used in bioanalytic systems to determine the concentrations of OPC. The purpose of the review is to analyze the main scientific results achieved over the past 10 years in the development of analytical systems based on enzymes intended for the determination of OPC. It is shown in the article, that the requirements for the sensitivity of biosensors are based on the norms of the content of the analyzed substances detected in/at the objects of mandatory control. The cholinesterases compose a basis for the development of the largest number of ultra-sensitive biosensors, although other enzymes can be successfully used as a biosensitive element. The most technologically advanced solution that is close to the practical implementation seems to be bioanalytical systems using immobilized enzymes. Improving the detection limits of the OPC can be achieved by using nanoobjects together with modern methods of signal transducers, for example, with nanomechanical detectors and signal converters. This combination of technical solutions ensures the sensitivity of the OPC analysis up to pg/l. At present, «reagentless» systems have received significant development, which have become the basis for the production of a large number of commercially available strips for the express determination of OPC. Modern demands stimulate the rapid development of portable and, especially, wearable biosensors that can be attached to various surfaces, including a clothing. The progress in the development of affine amino acid sequences, in the future, will allow the creation of enzyme biosensors on any surface.

scholarly journals Optimization of the sampling scheme for maps of physical and chemical properties estimated by kriging

2013 ◽  
Vol 37 (5) ◽  
pp. 1128-1135 ◽  
Author(s):  
Gener Tadeu Pereira ◽  
Zigomar Menezes de Souza ◽  
Daniel De Bortoli Teixeira ◽  
Rafael Montanari ◽  
José Marques Júnior
Keyword(s):  
Soil Properties ◽  
Chemical Property ◽  
Chemical Properties ◽  
Sampling Scheme ◽  
Optimal Sampling ◽  
Sampling Schemes ◽  
Medium Scale ◽  
Chemical Soil ◽  
Physical And Chemical Property ◽  
Physical And Chemical

The sampling scheme is essential in the investigation of the spatial variability of soil properties in Soil Science studies. The high costs of sampling schemes optimized with additional sampling points for each physical and chemical soil property, prevent their use in precision agriculture. The purpose of this study was to obtain an optimal sampling scheme for physical and chemical property sets and investigate its effect on the quality of soil sampling. Soil was sampled on a 42-ha area, with 206 geo-referenced points arranged in a regular grid spaced 50 m from each other, in a depth range of 0.00-0.20 m. In order to obtain an optimal sampling scheme for every physical and chemical property, a sample grid, a medium-scale variogram and the extended Spatial Simulated Annealing (SSA) method were used to minimize kriging variance. The optimization procedure was validated by constructing maps of relative improvement comparing the sample configuration before and after the process. A greater concentration of recommended points in specific areas (NW-SE direction) was observed, which also reflects a greater estimate variance at these locations. The addition of optimal samples, for specific regions, increased the accuracy up to 2 % for chemical and 1 % for physical properties. The use of a sample grid and medium-scale variogram, as previous information for the conception of additional sampling schemes, was very promising to determine the locations of these additional points for all physical and chemical soil properties, enhancing the accuracy of kriging estimates of the physical-chemical properties.

Transition-Metal-Catalyzed Synthesis of Organophosphorus Compounds Involving P–P Bond Cleavage

Synthesis ◽  
2020 ◽  
Vol 52 (19) ◽  
pp. 2795-2806 ◽  
Author(s):  
Mieko Arisawa
Keyword(s):  
Transition Metal ◽  
Organophosphorus Compounds ◽  
Bond Cleavage ◽  
Palladium Complexes ◽  
Addition Reactions ◽  
Phosphonium Salts ◽  
Substitution Reactions ◽  
Sulfonic Acids ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

Organophosphorus compounds are used as drugs, pesticides, detergents, food additives, flame retardants, synthetic reagents, and catalysts, and their efficient synthesis is an important task in organic synthesis. To synthesize novel functional organophosphorus compounds, transition-metal-catalyzed methods have been developed, which were previously considered difficult because of the strong bonding that occurs between transition metals and phosphorus. Addition reactions of triphenylphosphine and sulfonic acids to unsaturated compounds in the presence of a rhodium or palladium catalyst lead to phosphonium salts, in direct contrast to the conventional synthesis involving substitution reactions of organohalogen compounds. Rhodium and palladium complexes catalyze the cleavage of P–P bonds in diphosphines and polyphosphines and can transfer organophosphorus groups to various organic compounds. Subsequent substitution and addition reactions proceed effectively, without using a base, to provide various novel organophosphorus compounds.1 Introduction2 Transition-Metal-Catalyzed Synthesis of Phosphonium Salts by Addition Reactions of Triphenylphosphine and Sulfonic Acids3 Rhodium-Catalyzed P–P Bond Cleavage and Exchange Reactions4 Transition-Metal-Catalyzed Substitution Reactions Using Diphosphines4.1 Reactions Involving Substitution of a Phosphorus Group by P–P Bond Cleavage4.2 Related Substitution Reactions of Organophosphorus Compounds4.3 Substitution Reactions of Acid Fluorides Involving P–P Bond Cleavage of Diphosphines5 Rhodium-Catalyzed P–P Bond Cleavage and Addition Reactions6 Rhodium-Catalyzed P–P Bond Cleavage and Insertion Reactions Using Polyphosphines7 Conclusions

Investigation of physical and chemical property changes of ultra low-κ SiOCH in aspect of cleaning and chemical repair processes

2010 ◽  
Vol 87 (3) ◽  
pp. 457-461 ◽  
Author(s):  
Thomas Oszinda ◽  
Matthias Schaller ◽  
Daniel Fischer ◽  
Christine Walsh ◽  
Stefan E. Schulz
Keyword(s):  
Chemical Property ◽  
Repair Processes ◽  
Physical And Chemical Property ◽  
Property Changes ◽  
Physical And Chemical

Engineering Isoreticular 2D Metal–Organic Frameworks with Inherent Structural Flexibility

2017 ◽  
Vol 70 (5) ◽  
pp. 566 ◽  
Author(s):  
Alexandre Burgun ◽  
Witold M. Bloch ◽  
Christian J. Doonan ◽  
Christopher J. Sumby
Keyword(s):  
Metal Organic Frameworks ◽  
Mixed Valence ◽  
Chemical Properties ◽  
Fine Tuning ◽  
Gate Opening ◽  
Sterically Demanding ◽  
Metal Organic ◽  
Structure Metrics ◽  
Physical And Chemical ◽  
And Chemical Properties

The chemical mutability of metal–organic frameworks (MOFs) is an advantageous feature that allows fine-tuning of their physical and chemical properties. Herein, we report the successful isoreticulation of a MOF with an outstanding gas selectivity for CO2 versus N2: [Cu(L1)(H2O)]·xS (CuL1), where H2L1 = bis(4-(4-carboxyphenyl)-1H-pyrazolyl)methane) and S = solvate. By modifying the steric bulk and length of the original ligand, we synthesised three new MOFs with 2D networks isoreticular to CuL1, namely [Cu(L1Me)(H2O)]·xS (CuL1Me), [Cu(L2)(H2O)]·xS (CuL2), and [Cu(L2Me)(H2O)]·xS (CuL2Me) (where H2L1Me = bis(4-(4-carboxyphenyl)-3,5-dimethyl-1H-pyrazolyl)methane, H2L2 = bis(4-(4-carboxyphenyl)-(ethyne-2,1-yl)-1H-pyrazolyl)methane, and H2L2Me = bis(4-(4-carboxyphenyl)-(ethyne-2,1-yl)-3,5-dimethyl-1H-pyrazolyl)methane). Depending on the steric hindrance and structure metrics of the organic links, staggered and eclipsed arrangements of 2D 44 net layers were obtained. The anisotropy of the pore dimensions is proportional to the linker length (L2 and L2Me), which when increased, renders these materials non-porous. However, the more sterically demanding ligand L1Me gives a material that shows gate-opening behaviour in response to a CO2 absorbate. The synthesis and structure of an unexpected mixed-valence CuII/CuI 3D MOF, Cu3[Cu(L2Me)2]2(H2O)4]·xS (Cu5(L2Me)4), containing an unusual trimeric CuII node are also reported.

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