Polyphosphazenes

2005 ◽  
Author(s):  
James E. Mark ◽  
Harry R. Allcock ◽  
Robert West
Keyword(s):  
Molecular Structure ◽  
Main Chain ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Side Group ◽  
Polymer Backbone ◽  
Molecular Weights ◽  
Bonding Structure ◽  
Physical And Chemical ◽  
And Chemical Properties

Polyphosphazenes comprise by far the largest class of inorganic macromolecules. At least 700 different polymers of this type have been synthesized, with a range of physical and chemical properties that rivals that known hitherto only for synthetic organic macromolecules. Most polyphosphazenes have the general molecular structure. The polymer backbone consists of alternating phosphorus and nitrogen atoms, with two side groups, R, being attached to each phosphorus. The side groups may be organic, organometallic, or inorganic units. Each macromolecule typically contains from 100 to 15,000 or more repeating units linked end to end, which means that (depending on the organic side groups) the highest molecular weights are in the range of 2 million to 10 million. The bonding structure in the backbone is formally represented as a series of alternating single and double bonds. However, this formulation is misleading. Structural measurements suggest that all the bonds along the chain are equal or nearly equal in length, but without the extensive conjugation found in organic polyunsaturated materials. This anomaly will be discussed later. In addition to linear polyphosphazenes with one type of side group, other molecular architectures have also been assembled. These include polyphosphazenes in which two or more different side groups, R1 and R2, are arrayed along the chain in random, regular, or block distributions. Other species exist with short phosphazene branches linked to phosphorus atoms in the main chain. Also available are macromolecules in which carbon or sulfur replace some of the phosphorus atoms in the skeleton. Star-geometry structures, using the symbolism defined, are also accessible. A new and growing area is the field of phosphazene-organic and phosphazene-polysiloxane hybrid linear copolymers, and comb copolymers of the types. In addition, polymers are known in which six-membered phosphazene rings are side groups linked to organic polymers, and where phosphazene rings are linked by organic connector groups to form cyclolinear or cyclomatrix materials.

The Extraction of Main Chemical Compositions in Rumex Root

2011 ◽  
Vol 382 ◽  
pp. 372-374
Author(s):  
Yong Jiang ◽  
Zhi Bin Jiang ◽  
Guo Jie Shao ◽  
Dong Cheng Guo ◽  
Yu Tian ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Chemical Properties ◽  
Ethanol Extract ◽  
Chemical Compositions ◽  
Physical And Chemical Properties ◽  
Experimental Basis ◽  
Development And Utilization ◽  
Physical And Chemical ◽  
Root Methods ◽  
And Chemical Properties

Purpose: The purpose of this study was to study the compositions of the polygonaceae medicinal plants called rumex root. Methods: Solvent method and chromatography was used to purificate the chemical compositions of Rumex, and the molecular structure of the compound was identified by physical and chemical properties and spectral data. Results: Two compounds were obtained from the ethanol extract of rumex root, which were identified as Chrysophanol and Physcione. Conclusions: Experimental basis was provided for the further study of the active ingredients of rumex root and the development and utilization of medical resources.

On eccentricity-based topological descriptors of water-soluble dendrimers

2018 ◽  
Vol 74 (1-2) ◽  
pp. 25-33 ◽  
Author(s):  
Zahid Iqbal ◽  
Muhammad Ishaq ◽  
Adnan Aslam ◽  
Wei Gao
Keyword(s):  
Molecular Structure ◽  
Chemical Properties ◽  
Topological Indices ◽  
Water Soluble ◽  
Connectivity Index ◽  
Topological Descriptors ◽  
Physical And Chemical Properties ◽  
Eccentric Connectivity Index ◽  
Physical And Chemical ◽  
And Chemical Properties

AbstractPrevious studies show that certain physical and chemical properties of chemical compounds are closely related with their molecular structure. As a theoretical basis, it provides a new way of thinking by analyzing the molecular structure of the compounds to understand their physical and chemical properties. The molecular topological indices are numerical invariants of a molecular graph and are useful to predict their bioactivity. Among these topological indices, the eccentric-connectivity index has a prominent place, because of its high degree of predictability of pharmaceutical properties. In this article, we compute the closed formulae of eccentric-connectivity–based indices and its corresponding polynomial for water-soluble perylenediimides-cored polyglycerol dendrimers. Furthermore, the edge version of eccentric-connectivity index for a new class of dendrimers is determined. The conclusions we obtained in this article illustrate the promising application prospects in the field of bioinformatics and nanomaterial engineering.

scholarly journals Sila-Pharmaka, 14. Mitt. Darstellung und Eigenschaften sowie Kristall-und Molekülstruktur von Sila-Difenidol /Sila-Drugs, 14th Communication Preparation and Properties as well as Crystal and Molecular Structure of Sila-Difenidol

1979 ◽  
Vol 34 (9) ◽  
pp. 1279-1285 ◽  
Author(s):  
R. Tacke ◽  
M. Strecker ◽  
W. S. Sheldrick ◽  
E. Heeg ◽  
B. Berndt ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Hydrogen Bond ◽  
Mass Spectroscopy ◽  
Crystal And Molecular Structure ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
H Nmr ◽  
Physical And Chemical ◽  
And Chemical Properties

Abstract Sila-difenidol (6b), a sila-analogue of the drug difenidol (6a), was synthesized according to Scheme 1. 6b and its new precursors 3 and 5 were characterized by their physical and chemical properties, and their structures confirmed by elementary analyses, 1H NMR and mass spectroscopy. 6 b crystallizes orthorhombic P212121 with a = 11.523(1), b = 14.366(4), c = 11.450(1) Å, Z = 4, Dber = 1.14 gcm-3. The structure was refined to R = 0.050 for 1897 reflexions. A strong nearly linear intramolecular O-H···N hydrogen bond of 2.685 Å is observed. The anticholinergic, histaminolytic and musculotropic spasmolytic activities of 6 a and 6 b are reported.

scholarly journals ISOLATION AND STUDY OF PHYSICAL-CHEMICAL PROPERTIES OF GALACTOMANNANS FROM PLANT MA-TERIALS

2019 ◽  
pp. 35-41 ◽  
Author(s):  
Luiza Bakhtiyarovna Azimova ◽  
Nodaliy Sohbalalievich Normakhamatov ◽  
Saida Bokizhonovna Khaytmetova ◽  
Bakhtiyor Ikromovich Muhitdinov ◽  
Dilnoza Mukhtorovna Amonova ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Monosaccharide Composition ◽  
Extraction Methods ◽  
Physical And Chemical Properties ◽  
Sophora Japonica ◽  
Plant Materials ◽  
Molecular Weights ◽  
A Minor ◽  
Physical And Chemical ◽  
And Chemical Properties

The aim of the study is isolation of galactomannan from plant materials and investigation of their physical and chemical properties. Polysaccharides generally consisting of galactomannan were isolated and purified from galactomannans from these eds the plants Sophora japonica and Gleditsia triacanthos by cold and hot extraction methods. Galactose and mannose contents of the galactomannans isolated were quantitatively characterized and physical and chemical properties of the polysaccharides were studied. In addition, polysaccharides isolated were enzymatic hydrolyzed and changes in the monosaccharide composition in the hydrolysis process were studied. The characteristic viscosities of the initial and hydrolyzed galactomannans were 4.85–3.80 dl/g, respectively. Molecular weights of the galactomannans, after treatment with the enzyme, changed in a range of 55600–26200 Da. Studies with 1H NMR and 13CNMR spectroscopy methods showed decreases in galactoside content of the hydrolyzed galactomannans, indicating the primary course of hydrolysis occurs by the side chain of the macromolecule. Increase in duration of enzymatic hydrolysis more than 24 hours led to the formation of poly-mannans with a minor content of galactose units. The obtained data can serve to improve isolation and preparation of galactomannan based materials for biomedical purposes.

scholarly journals Synthesis of Hydrophilic Polyelectrolyte as Draw Solute for Forward Osmosis Process

2017 ◽  
Vol 20 (1) ◽  
Author(s):  
W. Khongnakorn ◽  
W. Bootluck
Keyword(s):  
Functional Group ◽  
Forward Osmosis ◽  
Chemical Properties ◽  
Solute Flux ◽  
Physical And Chemical Properties ◽  
Molecular Weights ◽  
Physical And Chemical ◽  
Lower Diffusion ◽  
And Chemical Properties

Synthesis and characterization of hydrophilic polyelectrolyte was performed in this work and used as draw solute for forward osmosis (FO) process. The effect of different ratios of acrylic acid (AA) and benzoyl peroxide (B) on the properties of polyelectrolyte was studied in this work. The physical and chemical properties of draw solution (DS) such as pH, conductivity, osmolality, viscosity, molecular weights and functional group were investigated. Results showed that the solution osmolality increased with increasing AA/B ratio. Self-synthesized polyelectrolytes with different molecular weights (MWs) were further correlated with its solution osmolality. The self-synthesized polyelectrolytes of PAA-K and PAA-Na showed an increasing of hydrophilic functional groups such as –OH or COOH. PAA-Na with lower MW and high osmotic pressure in the aqueous solution is found to exhibit a lower reverse solute flux during FO process. Meanwhile for the polyelectrolyte with higher MW, higher viscosity and lower diffusion coefficient were reported.

Statistical criteria of stellar population types

1966 ◽  
Vol 24 ◽  
pp. 101-110
Author(s):  
W. Iwanowska
Keyword(s):  
Stellar Population ◽  
Chemical Properties ◽  
Spectrophotometric Study ◽  
Physical And Chemical Properties ◽  
Population Type ◽  
The Galaxy ◽  
Distribution Parameters ◽  
Physical And Chemical ◽  
Statistical Criteria ◽  
And Chemical Properties

In connection with the spectrophotometric study of population-type characteristics of various kinds of stars, a statistical analysis of kinematical and distribution parameters of the same stars is performed at the Toruń Observatory. This has a twofold purpose: first, to provide a practical guide in selecting stars for observing programmes, second, to contribute to the understanding of relations existing between the physical and chemical properties of stars and their kinematics and distribution in the Galaxy.

Response of corn (Zea mays L.) to various organic-based fertilizers in marginal upland of Sta. Rita, Samar

2017 ◽  
pp. 31-43
Author(s):  
Berta Ratilla ◽  
Loreme Cagande ◽  
Othello Capuno
Keyword(s):  
Block Design ◽  
Management Strategies ◽  
Chemical Properties ◽  
Organic Fertilizers ◽  
Growth And Yield ◽  
Physical And Chemical Properties ◽  
Total N ◽  
Randomized Complete Block Design ◽  
Physical And Chemical ◽  
And Chemical Properties

Organic farming is one of the management strategies that improve productivity of marginal uplands. The study aimed to: (1) evaluate effects of various organic-based fertilizers on the growth and yield of corn; (2) determine the appropriate combination for optimum yield; and (3) assess changes on the soil physical and chemical properties. Experiment was laid out in Randomized Complete Block Design, with 3 replications and 7 treatments, namely; T0=(0-0-0); T1=1t ha-1 Evans + 45-30-30kg N, P2O5, K2O ha-1; T2=t ha-1 Wellgrow + 45-30-30kg N, P2O5, K2O ha-1; T3=15t ha-1 chicken dung; T4=10t ha-1 chicken dung + 45-30-30kg N, P2O5, K2O ha-1; T5=15t ha-1 Vermicast; and T6=10t ha-1 Vermicast + 45-30-30kg N, P2O5, K2O ha-1. Application of organic-based fertilizers with or without inorganic fertilizers promoted growth of corn than the control. But due to high infestation of corn silk beetle(Monolepta bifasciata Horns), its grain yield was greatly affected. In the second cropping, except for Evans, any of these fertilizers applied alone or combined with 45-30-30kg N, P2O5, K2O ha-1 appeared appropriate in increasing corn earyield. Soil physical and chemical properties changed with addition of organic fertilizers. While bulk density decreased irrespective of treatments, pH, total N, available P and exchangeable K generally increased more with chicken dung application.

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