scholarly journals Information Entropy of Regular Dendrimer Aggregates and Irregular Intermediate Structures

Liquids ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 25-35
Author(s):  
Denis Sabirov ◽  
Alina Tukhbatullina ◽  
Igor Shepelevich

Dendrimer molecules and aggregates are chemical structures with regular branching that underlies their physicochemical properties. Regular dendrimers have been studied both theoretically and experimentally, but the irregular intermediate structures between the dendrimers of neighboring generations have not. In the present work, dendrimer aggregates, both regular and intermediate, are investigated in terms of the information entropy approach. As found, the information entropy of the regular dendrimer asymptotically increases with the generation number; herewith, its maximal value equals 2. The intermediate structures have been studied for the growing dendrimer G1 → G2 → G3 → G4 with the tricoordinated building block. The plot of the information entropy of the growing dendrimer on the size has the frontier consisting of the lowest values that correspond to the regular and irregular structures described with the symmetrical graphs. Other intermediate structures have information entropies higher than the regular dendrimers. Thus, to move the system from one informationally stable state to another, its information capacity must be temporarily increased.

2020 ◽  
Author(s):  
R.P. Vivek-Ananth ◽  
Ajaya Kumar Sahoo ◽  
Kavyaa Kumaravel ◽  
Karthikeyan Mohanraj ◽  
Areejit Samal

AbstractFungi are a rich source of secondary metabolites which constitutes a valuable and diverse chemical space of natural products. Medicinal fungi have been used in traditional medicine to treat human ailments for centuries. To date, there is no devoted resource on secondary metabolites and therapeutic uses of medicinal fungi. Such a dedicated resource compiling dispersed information on medicinal fungi across published literature will facilitate ongoing efforts towards natural product based drug discovery. Here, we present the first comprehensive manually curated database on Medicinal Fungi Secondary metabolites And Therapeutics (MeFSAT) that compiles information on 184 medicinal fungi, 1830 secondary metabolites and 149 therapeutics uses. Importantly, MeFSAT contains a non-redundant in silico natural product library of 1830 secondary metabolites along with information on their chemical structures, computed physicochemical properties, drug-likeness properties, predicted ADMET properties, molecular descriptors and predicted human target proteins. By comparing the physicochemical properties of secondary metabolites in MeFSAT with other small molecules collections, we find that fungal secondary metabolites have high stereochemical complexity and shape complexity similar to other natural product libraries. Based on multiple scoring schemes, we have filtered a subset of 228 drug-like secondary metabolites in MeFSAT database. By constructing and analyzing chemical similarity networks, we show that the chemical space of secondary metabolites in MeFSAT is highly diverse. The compiled information in MeFSAT database is openly accessible at: https://cb.imsc.res.in/mefsat/.


2020 ◽  
Vol 137 ◽  
pp. 109576
Author(s):  
Bruna Larissa Spontoni do Espirito Santo ◽  
Érica Caroline da Silva ◽  
Camila Jordão Cândido ◽  
Anderson Fernandes da Silva ◽  
Valter Aragão do Nascimento ◽  
...  

1983 ◽  
Vol 36 (10) ◽  
pp. 1284-1289 ◽  
Author(s):  
YOSHIFUMI IKEDA ◽  
HIDEO MATSUKI ◽  
TAKAYUKI OGAWA ◽  
TOMOHIKO MUNAKATA

2019 ◽  
Vol 72 (2) ◽  
pp. 55 ◽  
Author(s):  
Hideki Hanabusa ◽  
Yuko Takeoka ◽  
Masahiro Rikukawa ◽  
Masahiro Yoshizawa-Fujita

A protic ionic liquid (PIL) composed of 1,8-diazabicyclo[5.4.0]-undec-7-ene (DBU) and acetic acid can dissolve cellulose under mild conditions and catalyse its transesterification. To investigate the relationship between physicochemical properties and chemical structures, PILs composed of DBU and carboxylic acids with varying alkyl chain lengths were prepared as cellulose-dissolving solvents. The thermal behaviours of the PILs were analysed by thermogravimetry and differential scanning calorimetry, and their viscosities, ionic conductivities, and cellulose-dissolution abilities were determined. The effect of the alkyl chain length in the carboxylate ion on the physicochemical properties of the PILs was investigated. With increasing chain length, the thermal stability and ionic conductivity increased, whereas the melting point (Tm), glass-transition temperature (Tg), cellulose solubility, and viscosity decreased. The cellulose solubility increased as the difference between the pKa values of the DBU and carboxylic acid (ΔpKa) increased. In addition, the cellulose solubility increased with the increasing density of the PIL. It was revealed that PILs with a high ΔpKa value and a carboxylate ion with a short alkyl chain are suitable for cellulose dissolution.


2018 ◽  
Vol 26 (1) ◽  
pp. 91-104 ◽  
Author(s):  
Prosanta Sarkar ◽  
Nilanjan De ◽  
Anita Pal

Abstract In chemical graph theory, chemical structures are model edthrough a graph where atoms are considered as vertices and edges are bonds between them. In chemical sciences, topological indices are used for understanding the physicochemical properties of molecules. In this work, we study the generalized Zagreb index for three types of carbon allotrope’s theoretically.


Molecules ◽  
2019 ◽  
Vol 24 (17) ◽  
pp. 3049 ◽  
Author(s):  
Elżbieta Łodyga-Chruścińska ◽  
Agnieszka Kowalska-Baron ◽  
Paulina Błazińska ◽  
Maria Pilo ◽  
Antonio Zucca ◽  
...  

Structure-related biological activities of flavanones are still considered largely unexplored. Since they exhibit various medicinal activities, it is intriguing to enter deeper into their chemical structures, electronic transitions or interactions with some biomolecules in order to find properties that allow us to better understand their effects. Little information is available on biological activity of flavanone and its monohydroxy derivatives in relation to their physicochemical properties as spectral profiles, existence of protonated/deprotonated species under pH changes or interaction with Calf Thymus DNA. We devoted this work to research demonstrating differences in the physicochemical properties of the four flavanones: flavanone, 2′-hydroxyflavanone, 6-hydroxyflavanone and 7-hydroxyflavanone and linking them to their biological activity. Potentiometric titration, UV–Vis spectroscopy were used to investigate influence of pH on acid–base and spectral profiles and to propose the mode of interaction with DNA. Cyclic voltammetry was applied to evaluate antioxidant potentiality and additionally, theoretical DFT(B3LYP) method to disclose electronic structure and properties of the compounds. Molecular geometries, proton affinities and pKa values have been determined. According to computational and cyclic voltammetry results we could predict higher antioxidant activity of 6-hydroxyflavanone with respect to other compounds. The values of Kb intrinsic binding constants of the flavanones indicated weak interactions with DNA. Structure–activity relationships observed for antioxidant activity and DNA interactions suggest that 6-hydroxyflavanone can protect DNA against oxidative damage most effectively than flavanone, 2′-hydroxyflavanone or 7-hydroxyflavanone.


2020 ◽  
Vol 11 (1) ◽  
pp. 7700-7711 ◽  

A topological index is a numerical quantity connected with a graph describing the molecular topology of the graph. It can predict different physicochemical properties such as boiling point, entropy, acentric factor etc. of chemical compounds. Dendrimers are highly branched nanostructures that are regarded as a building block in nanotechnology having wide applications. In this paper, multiplicative degree-based topological indices are computed for some nanostar dendrimers. The derived results have the potential for implementation in the chemical, biological, and pharmaceutical sciences.


Author(s):  
Juanyan Fang ◽  
Muhammad Rafiullah ◽  
Hafiz Muhammad Afzal Siddiqui

Background: Sierpinski graphs S(n,k) are largely studied because of their fractal nature with applications in topology, chemistry, mathematics of Tower of Hanoi, and computer sciences. Applications of molecular structure descriptors are a standard procedure that are used to correlate the biological activity of molecules with their chemical structures and thus can be helpful in the field of pharmacology. Objective: The aim of this article is to establish analytically closed computing formulae for eccentricity-based descriptors of Sierpinski networks and their regularizations. These computing formulae are useful to determine a large number of properties like thermodynamic properties, physicochemical properties, chemical and biological activity of chemical graphs. Methods: At first, vertex sets have been partitioned on the basis of their degrees, eccentricities, and frequencies of occurrence. Then these partitions are used to compute the eccentricity-based indices with the aid of some combinatorics. Results: The total eccentric index and eccentric-connectivity index have been computed. We also compute some eccentricity-based Zagreb indices of the Sierpinski networks. Moreover, a comparison has also been presented in the form of graphs. Conclusion: These computations will help the readers to estimate the thermodynamic properties, physicochemical properties of chemical structures, which are of fractal nature and can not be dealt with easily. A 3D graphical representation is also presented to understand the dynamics of the aforementioned topological descriptors.


2013 ◽  
Vol 55 (7) ◽  
pp. 427-437 ◽  
Author(s):  
T. G. Volova ◽  
N. O. Zhila ◽  
E. I. Shishatskaya ◽  
P. V. Mironov ◽  
A. D. Vasil’ev ◽  
...  

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