scholarly journals A Survey of Quantitative Descriptions of Molecular Structure

2013 ◽  
Vol 12 (18) ◽  
pp. 1946-1956 ◽  
Author(s):  
Rajarshi Guha ◽  
Egon Willighagen
Keyword(s):  
Molecular Structure ◽  
Chemical Structure ◽  
Computational Analysis ◽  
Molecular Descriptor ◽  
Molecular Graph ◽  
Molecular Surface ◽  
Numerical Characterization ◽  
Numerical Representations ◽  
Simple Atom

Numerical characterization of molecular structure is a first step in many computational analysis of chemical structure data. These numerical representations, termed descriptors, come in many forms, ranging from simple atom counts and invariants of the molecular graph to distribution of properties, such as charge, across a molecular surface. In this article we first present a broad categorization of descriptors and then describe applications and toolkits that can be employed to evaluate them. We highlight a number of issues surrounding molecular descriptor calculations such as versioning and reproducibility and describe how some toolkits have attempted to address these problems.

scholarly journals Synthesis and Characterization of Novel Thieno-Fused Bicyclic Compounds through New Enaminone Containing Thieno[2,3-b]pyridine Scaffold

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Yahia Nasser Mabkhot ◽  
Salah S. Aladdi ◽  
S. S. Al-Showiman ◽  
A. M. A. Al-Majid ◽  
Assem Barakat ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Single Crystal ◽  
Chemical Structure ◽  
Synthesis And Characterization ◽  
Spectroscopic Methods ◽  
X Ray ◽  
Bicyclic Compounds

New substituted thieno-fused bicyclic compounds named (1H-pyrazol-3-yl)thieno[2,3-b]pyridin-4(7H)-one derivatives (4a,b), 2-([1,2,4]triazolo[1,5-a]pyrimidin-7-yl)-3-methyl-7-phenylthieno[2,3-b]pyridin-4(7H)-one (5), phenylthieno[2,3-b]pyridin-4(7H)-one derivatives (6a–c,7a–c, and8), and 3-(3-methyl-4-oxo-7-phenyl-4,7-dihydrothieno[2,3-b]pyridin-2-yl)-3-oxopropyl 4-chlorobenzoate (9) were synthesized by reacting the new enaminone (3) with different reagents. The chemical structure of the new molecules was determined by means of different spectroscopic methods such as NMR, IR, MS spectrometry, and by CHN analyses. The molecular structure of the 1,1′-(3-methyl-5-(phenylamino)thiophene-2,4-diyl)diethanone (2) was successfully solved by X-ray single crystal.

scholarly journals Forgotten Coindex for the Derived Sum Graphs under Cartesian Product

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Muhammad Ibraheem ◽  
Meshari M. Aljohani ◽  
Muhammad Javaid ◽  
Abdulaziz Mohammed Alanazi
Keyword(s):  
Mathematical Method ◽  
Surface Tension ◽  
Chemical Structure ◽  
Topological Index ◽  
Laboratory Experiments ◽  
Molecular Descriptor ◽  
Molecular Graph ◽  
Cartesian Product ◽  
Volume Density ◽  
Total Graph

A topological index (TI) is a molecular descriptor that is applied on a chemical structure to compute the associated numerical value which measures volume, density, boiling point, melting point, surface tension, or solubility of this structure. It is an efficient mathematical method in avoiding laboratory experiments and time-consuming. The forgotten coindex of a structure or (molecular) graph H is defined as the sum of the degrees of all the possible pairs of nonadjacent vertices in H . For D ∈ S , R , Q , T and the connected graph H , the derived graphs D H are obtained by applying the operations S (subdivided), R (triangle parallel), Q (line superposition), and T (total graph), respectively. Moreover, a derived sum graph ( D -sum graph) is obtained by the Cartesian product of the graph H 2 with the graph D H 1 . In this study, we compute forgotten coindex of the D -sum graphs H 1 + S H 2 ( S -sum), H 1 + R H 2 ( R -sum), H 1 + Q H 2 ( Q -sum), and H 1 + T H 2 ( T -sum) in the form of various indices and coindices of the factor graphs H 1 and H 2 . At the end, we have analyzed our results using numerical tables and graphical behaviour for some particular D -sum graphs.

Preparation and Characterization of Soybean Oil-based Flame Retardant Rigid Polyurethane Foams Containing Phosphaphenanthrene Groups

2020 ◽  
Vol 17 (10) ◽  
pp. 760-771
Author(s):  
Qirui Gong ◽  
Niangui Wang ◽  
Kaibo Zhang ◽  
Shizhao Huang ◽  
Yuhan Wang
Keyword(s):  
Soybean Oil ◽  
Flame Retardant ◽  
Chemical Structure ◽  
Cell Structure ◽  
Polyurethane Foams ◽  
Limiting Oxygen Index ◽  
Rigid Polyurethane Foams ◽  
Degradation Activation Energy ◽  
Ft Ir

A phosphaphenanthrene groups containing soybean oil based polyol (DSBP) was synthesized by epoxidized soybean oil (ESO) and 9,10-dihydro-oxa-10-phosphaphenanthrene-10-oxide (DOPO). Soybean oil based polyol (HSBP) was synthesized by ESO and H2O. The chemical structure of DSBP and HSBP were characterized with FT-IR and 1H NMR. The corresponding rigid polyurethane foams (RPUFs) were prepared by mixing DSBP with HSBP. The results revealed apparent density and compression strength of RPUFs decreased with increasing the DSBP content. The cell structure of RPUFs was examined by scanning electron microscope (SEM) which displayed the cells as spherical or polyhedral. The thermal degradation and flame retardancy of RPUFs were investigated by thermogravimetric analysis, limiting oxygen index (LOI), and UL 94 vertical burning test. The degradation activation energy (Ea) of first degradation stage reduced from 80.05 kJ/mol to 37.84 kJ/mol with 80 wt% DSBP. The RUPF with 80 wt% DSBP achieved UL94 V-0 rating and LOI 28.3. The results showed that the flame retardant effect was mainly in both gas phase and condensed phase.

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