Wiener Indices and Molecular Surfaces

1995 ◽  
Vol 50 (7) ◽  
pp. 669-671 ◽  
Author(s):  
Ivan Gutmana ◽  
Tamás Körtvélyesi
Keyword(s):  
Volume Ratio ◽  
Wiener Index ◽  
Molecular Surface ◽  
Molecular Volume ◽  
Saturated Hydrocarbons ◽  
Molecular Surfaces ◽  
Physico Chemical ◽  
First Time

A correlation between the Wiener index (W) and the molecular surface of the respective alkane is established for the first time. This correlation is curvilinear and not particularly good. W is only weakly correlated to molecular volume of saturated hydrocarbons and does not reflect at all their surface-to-volume ratio. By this a long-existing controversy concerning the physico-chemical interpretation of W is resolved.

scholarly journals Extremal Chemical Trees

2002 ◽  
Vol 57 (1-2) ◽  
pp. 49-51
Author(s):  
Miranca Fischermann ◽  
Ivan Gutman ◽  
Arne Hoffmann ◽  
Dieter Rautenbach ◽  
Dušica Vidovića ◽  
...  
Keyword(s):  
Carbon Atom ◽  
Molecular Graph ◽  
Chemical Properties ◽  
Wiener Index ◽  
Graph Representation ◽  
Hosoya Index ◽  
Saturated Hydrocarbons ◽  
Physico Chemical ◽  
Graph Energy ◽  
Chemical Trees

A variety of molecular-graph-based structure-descriptors were proposed, in particular the Wiener index W. the largest graph eigenvalue λ1, the connectivity index X, the graph energy E and the Hosoya index Z, capable of measuring the branching of the carbon-atom skeleton of organic compounds, and therefore suitable for describing several of their physico-chemical properties. We now determine the structure of the chemical trees (= the graph representation of acyclic saturated hydrocarbons) that are extremal with respect to W , λ1, E, and Z. whereas the analogous problem for X was solved earlier. Among chemical trees with 5. 6, 7, and 3k + 2 vertices, k = 2,3,..., one and the same tree has maximum λ1 and minimum W, E, Z. Among chemical trees with 3k and 3k +1 vertices, k = 3,4...., one tree has minimum 11 and maximum λ1 and another minimum E and Z .

Extremal Chemical Trees

2002 ◽  
Vol 57 (9-10) ◽  
pp. 49-52 ◽  
Author(s):  
Miranca Fischermann ◽  
Ivan Gutmana ◽  
Arne Hoffmann ◽  
Dieter Rautenbach ◽  
Dušica Vidović ◽  
...  
Keyword(s):  
Carbon Atom ◽  
Molecular Graph ◽  
Chemical Properties ◽  
Wiener Index ◽  
Graph Representation ◽  
Hosoya Index ◽  
Saturated Hydrocarbons ◽  
Physico Chemical ◽  
Graph Energy ◽  
Chemical Trees

Avariety of molecular-graph-based structure-descriptors were proposed, in particular the Wiener index W, the largest graph eigenvalue λ1, the connectivity index χ, the graph energy E and the Hosoya index Z, capable of measuring the branching of the carbon-atom skeleton of organic compounds, and therefore suitable for describing several of their physico-chemical properties. We now determine the structure of the chemical trees (= the graph representation of acyclic saturated hydrocarbons) that are extremal with respect to W, λ1, E, and Z, whereas the analogous problem for χ was solved earlier. Among chemical trees with 5, 6, 7, and 3k + 2 vertices, k = 2, 3,..., one and the same tree has maximum λ1 and minimum W, E, Z. Among chemical trees with 3k and 3k + 1 vertices, k = 3, 4..., one tree has minimum W and maximum λ1 and another minimum E and Z.

QSAR Study of ORL1 Agonist Analgesic Effect of Some Imidazoles with Molecular Descriptors

2018 ◽  
Vol 69 (2) ◽  
pp. 459-462 ◽  
Author(s):  
Octavian Istratoaie ◽  
Luciana Teodora Rotaru ◽  
Renata Maria Varut ◽  
Marius Ciprian Varut ◽  
Mircea Catalin Fortofoiu ◽  
...  
Keyword(s):  
Total Energy ◽  
Analgesic Effect ◽  
Heat Of Formation ◽  
Correlation Study ◽  
Molecular Surface ◽  
Molecular Volume ◽  
Qsar Study ◽  
Physico Chemical ◽  
Homo And Lumo ◽  
Chemical Descriptors

Imidazole and its derivates represent an interesting source of study for researchers for more than a century and was recently studied for their analgesic effect by ORL-1 receptor agonist effect on. In the theoretical study we used molecular mechanics programs and we characterized the structural properties for a series of ten imidazoles. The selected physico-chemical descriptors were: the HOMO and LUMO frontier orbitals, the dipole moment, the heat of formation, the total energy of the molecule, the ionization energy, the surface area and the molecular volume. From the correlation study we noticed the dependence between the analgesic effect and the total energy, the area of the molecular surface and the molecular volume.

scholarly journals Weighted Wiener Indices of Molecular Graphs with Application to Alkenes and Alkadienes

Mathematics ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 153
Author(s):  
Simon Brezovnik ◽  
Niko Tratnik ◽  
Petra Žigert Pleteršek
Keyword(s):  
Linear Regression Analysis ◽  
Chemical Properties ◽  
Wiener Index ◽  
Topological Indices ◽  
The Other ◽  
Multiple Bonds ◽  
Saturated Hydrocarbons ◽  
Simple Graphs ◽  
Boiling Points ◽  
Physico Chemical

There exist many topological indices that are calculated on saturated hydrocarbons since they can be easily modelled by simple graphs. On the other hand, it is more challenging to investigate topological indices for hydrocarbons with multiple bonds. The purpose of this paper is to introduce a simple model that gives good results for predicting physico-chemical properties of alkenes and alkadienes. In particular, we are interested in predicting boiling points of these molecules by using the well known Wiener index and its weighted versions. By performing the non-linear regression analysis we predict boiling points of alkenes and alkadienes.

scholarly journals Piroxicam Loading onto Mesoporous Silicas by Supercritical CO2 Impregnation

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2500
Author(s):  
Marta Gallo ◽  
Luca Serpella ◽  
Federica Leone ◽  
Luigi Manna ◽  
Mauro Banchero ◽  
...  
Keyword(s):  
Supercritical Co2 ◽  
Water Solubility ◽  
Solid Dispersions ◽  
Mesoporous Silicas ◽  
Incipient Wetness Impregnation ◽  
Pore Blocking ◽  
Physico Chemical ◽  
Adsorption From Solution ◽  
First Time ◽  
Loading Procedure

Piroxicam (PRX) is a commonly prescribed nonsteroidal anti-inflammatory drug. Its efficacy, however, is partially limited by its low water solubility. In recent years, different studies have tackled this problem and have suggested delivering PRX through solid dispersions. All these strategies, however, involve the use of potentially harmful solvents for the loading procedure. Since piroxicam is soluble in supercritical CO2 (scCO2), the present study aims, for the first time, to adsorb PRX onto mesoporous silica using scCO2, which is known to be a safer and greener technique compared to the organic solvent-based ones. For comparison, PRX is also loaded by adsorption from solution and incipient wetness impregnation using ethanol as solvent. Two different commercial mesoporous silicas are used (SBA-15 and Grace Syloid® XDP), which differ in porosity order and surface silanol population. Physico-chemical analyses show that the most promising results are obtained through scCO2, which yields the amorphization of PRX, whereas some crystallization occurs in the case of adsorption from solution and IWI. The highest loading of PRX by scCO2 is obtained in SBA-15 (15 wt.%), where molecule distribution appears homogeneous, with very limited pore blocking.

scholarly journals Monoclinic and Orthorhombic NaMnO2 for Secondary Batteries: A Comparative Study

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1230
Author(s):  
Jessica Manzi ◽  
Annalisa Paolone ◽  
Oriele Palumbo ◽  
Domenico Corona ◽  
Arianna Massaro ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Reversible Capacity ◽  
Beta Phase ◽  
X Ray Diffraction ◽  
Positive Electrodes ◽  
Detailed Structural Analysis ◽  
Physico Chemical ◽  
Sodium Batteries ◽  
The Impact ◽  
First Time

In this manuscript, we report a detailed physico-chemical comparison between the α- and β-polymorphs of the NaMnO2 compound, a promising material for application in positive electrodes for secondary aprotic sodium batteries. In particular, the structure and vibrational properties, as well as electrochemical performance in sodium batteries, are compared to highlight differences and similarities. We exploit both laboratory techniques (Raman spectroscopy, electrochemical methods) and synchrotron radiation experiments (Fast-Fourier Transform Infrared spectroscopy, and X-ray diffraction). Notably the vibrational spectra of these phases are here reported for the first time in the literature as well as the detailed structural analysis from diffraction data. DFT+U calculations predict both phases to have similar electronic features, with structural parameters consistent with the experimental counterparts. The experimental evidence of antisite defects in the beta-phase between sodium and manganese ions is noticeable. Both polymorphs have been also tested in aprotic batteries by comparing the impact of different liquid electrolytes on the ability to de-intercalated/intercalate sodium ions. Overall, the monoclinic α-NaMnO2 shows larger reversible capacity exceeding 175 mAhg−1 at 10 mAg−1.

SECONDARY CHANGES IN CARBONATE ROCKS OF OIL AND GAS COMPLEXES

2020 ◽  
pp. 18-23
Author(s):  
M.A. Tugarova
Keyword(s):  
Carbonate Rocks ◽  
Oil And Gas ◽  
Carbonate Reservoirs ◽  
Fundamental Importance ◽  
Schematic Diagram ◽  
Reservoir Properties ◽  
Physico Chemical ◽  
Chemical Conditions ◽  
First Time

The article considers the secondary transformations of carbonate rocks of oil and gas complexes, which are of fundamental importance in the formation of reservoir properties. For the first time, a schematic diagram, illustrating the regularities of secondary processes in carbonate reservoirs and their relationship with the physico-chemical conditions of the stratosphere is proposed.

scholarly journals Cyclam-Based Chelators Bearing Phosphonated Pyridine Pendants for 64Cu-PET Imaging : Synthesis, Physico-Chemical Studies, Radiolabeling and Bioimaging.

2020 ◽  
Author(s):  
Richard Knighton ◽  
Thibault Troadec ◽  
Valerie Mazan ◽  
Patricia La Saëc ◽  
Séverine Marionneau-Lambot ◽  
...  
Keyword(s):  
Pet Imaging ◽  
Copper Complexes ◽  
The Body ◽  
Renal Elimination ◽  
X Ray Diffraction ◽  
Physico Chemical ◽  
Chemical Studies ◽  
First Time ◽  
Excellent Stability

Herein we present the preparation of two novel cyclam-based macrocycles (te1pyp and cb-te1pyp), bearing phosphonate-appended pyridine side-arms for the coordination of copper(II) ions in the context of 64Cu PET imaging. The two ligands have been prepared through conventional protection-alkylation sequences on cyclam, and their coordination properties have been thoroughly investigated. The corresponding copper complexes have been fully characterized in the solid-state (X-Ray diffraction analysis) and in solution (EPR and UV-Vis spectroscopies). Potentiometric studies, combined with spectrometry, have also allowed us to determine their thermodynamic stability constants, confirming their high affinity for copper(II) cations. The kinetic inertness of the complexes has also been verified by acid-assisted dissociation experiments, enabling their use in 64Cu-PET imaging in mice for the first time. Indeed, the two ligands could be quantitatively radiolabeled under mild conditions, and the resulting 64Cu complexes have demonstrated excellent stability in serum. PET imaging demon-strated a set of features emerging from the combination of picolinates and phosphonate units: high stability in vivo, fast clear-ance from the body via renal elimination, and most interestingly, very low fixation in the liver. The latter is in contrast with what was observed for monopicolinate cyclam (te1pa), that had a non-negligible accumulation in the liver, owing probably to its different charge and lipophillicity. These results thus pave the way for the use of such phosphonated pyridine chelators for in vivo 64Cu-PET imaging.

scholarly journals Cyclam-Based Chelators Bearing Phosphonated Pyridine Pendants for 64Cu-PET Imaging : Synthesis, Physico-Chemical Studies, Radiolabeling and Bioimaging.

2020 ◽  
Author(s):  
Richard Knighton ◽  
Thibault Troadec ◽  
Valerie Mazan ◽  
Patricia La Saëc ◽  
Séverine Marionneau-Lambot ◽  
...  
Keyword(s):  
Pet Imaging ◽  
Copper Complexes ◽  
The Body ◽  
Renal Elimination ◽  
X Ray Diffraction ◽  
Physico Chemical ◽  
Chemical Studies ◽  
First Time ◽  
Excellent Stability

Herein we present the preparation of two novel cyclam-based macrocycles (te1pyp and cb-te1pyp), bearing phosphonate-appended pyridine side-arms for the coordination of copper(II) ions in the context of 64Cu PET imaging. The two ligands have been prepared through conventional protection-alkylation sequences on cyclam, and their coordination properties have been thoroughly investigated. The corresponding copper complexes have been fully characterized in the solid-state (X-Ray diffraction analysis) and in solution (EPR and UV-Vis spectroscopies). Potentiometric studies, combined with spectrometry, have also allowed us to determine their thermodynamic stability constants, confirming their high affinity for copper(II) cations. The kinetic inertness of the complexes has also been verified by acid-assisted dissociation experiments, enabling their use in 64Cu-PET imaging in mice for the first time. Indeed, the two ligands could be quantitatively radiolabeled under mild conditions, and the resulting 64Cu complexes have demonstrated excellent stability in serum. PET imaging demon-strated a set of features emerging from the combination of picolinates and phosphonate units: high stability in vivo, fast clear-ance from the body via renal elimination, and most interestingly, very low fixation in the liver. The latter is in contrast with what was observed for monopicolinate cyclam (te1pa), that had a non-negligible accumulation in the liver, owing probably to its different charge and lipophillicity. These results thus pave the way for the use of such phosphonated pyridine chelators for in vivo 64Cu-PET imaging.

scholarly journals Surface-Ionized thermosensitive poly(N-isopropylacryl amide) hydrogels with faster response

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Xiao Xin-Cai
Keyword(s):  
Volume Ratio ◽  
Temperature Cycling ◽  
Solution Temperature ◽  
Hydroxyl Groups ◽  
Critical Solution Temperature ◽  
Temperature Responsive ◽  
Microgel Particles ◽  
Concentrated Sulfuric Acid ◽  
Response To Temperature ◽  
First Time

AbstractPoly(N-isopropylacrylamide) hydrogels have been successfully modified by concentrated sulfuric acid for the first time. The modified hydrogels displayed faster, larger magnitude and hydration/dehydration dynamic response to temperature cycling without increasing the lower critical solution temperature (LCST). These contributions were attributed to sulphate ester groups resulting from terminal hydroxyl groups of poly(N-isopropylacrylamide). These results may lead to technological application for temperature-responsive thin film and microgel particles with higher surface-to-volume ratio.

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