scholarly journals Solvatochromic Study of Two Pyridazinium Ylids Binary Solutions

2016 ◽  
Vol 22 (3) ◽  
pp. 598-602
Author(s):  
Daniela Babuşca ◽  
Cezarina Ana Moroşanu ◽  
Dana Ortansa Dorohoi
Keyword(s):  
Solubility Parameter ◽  
Intramolecular Charge Transfer ◽  
Spectral Shift ◽  
Solvent Interactions ◽  
Binary Solutions ◽  
Spectral Shifts ◽  
Different Types ◽  
Linear Solvation Energy ◽  
Solvent Molecules ◽  
Parameter Values

Abstract The wavenumbers in the maximum of intramolecular charge transfer (ICT) visibile band of two pyridazinium ylids binary solutions were analized using Kamlet and Taft empirical parameters and the Hildebrand’s solubility parameter. The Hildebrand’s solubility parameter values, δH2, measures the energy needed to separate the solvent molecules. A linear solvation energy relationship (LSER) allows separating the contributions of different types of interactions to the total spectral shift. The supply of universal and specific interactions as well as the supply of solvent-solvent interactions to the total spectral shifts was calculated.

Heats of Solution of Some Sodium and Potassium Salts in Water and in Water-Methanol Mixtures

1992 ◽  
Vol 57 (11) ◽  
pp. 2227-2234 ◽  
Author(s):  
Ján Benko ◽  
Oľga Vollárová
Keyword(s):  
Transfer Functions ◽  
Enthalpies Of Solution ◽  
Potassium Salts ◽  
Solvent Interactions ◽  
Heats Of Solution ◽  
Solvent Molecules ◽  
Sodium And Potassium

The enthalpies of solution ∆Hs0 were determined for NaSCN, KSCN, NaBrO3, KBrO3, NaClO3, KClO3, NaIO4, KMnO4, KNO2 and NaNO2 in water-methanol mixtures. The transfer functions ∆Ht0 of the salts and anions were calculated based on the extrathermodynamic TPTB assumption. The ∆Ht0 values of the anion obtained from the sodium and potassium salts were compared. The differences observed, particularly at higher concentrations of the cosolvent, are discussed with respect to the interactions between the solvent molecules and the solute-solvent interactions.

scholarly journals Photochemical R2PI study of chirality and intermolecular forces in supersonic beam

2001 ◽  
Vol 3 (4) ◽  
pp. 223-227 ◽  
Author(s):  
A. Giardini Guidoni ◽  
S. Piccirillo ◽  
D. Scuderi ◽  
M. Satta ◽  
T. M. Di Palma ◽  
...  
Keyword(s):  
Excited States ◽  
Molecular Beam ◽  
Intermolecular Forces ◽  
Excitation Spectra ◽  
Supersonic Molecular Beam ◽  
Spectral Shifts ◽  
Band Origin ◽  
Solvent Molecules ◽  
The One ◽  
Diastereomeric Complexes

One and two-color, mass selected R2PI spectra of theS1←S0transitions in the bare(+)-(R)- 1-phenyl-1-ethanol(ER) and its complexes with different solvent molecules (solv) (-)-(R)-2-butanol(BR) or(+)-(S)-2-butanol(BS), (—)-(R)-2-pentanol (TR) or(+)-(S)-2-pentanol(TS) and(-)-(R)-2-butylamine(AR) or(+)-(S)-2-butylamine(AS), have been recorded after a supersonic molecular beam expansion. The one-color R2PI excitation spectra of the diastereomeric complexes are characterized by significant shifts of their band origin relative to that of bareER. The extent and the direction of these spectral shifts are found to depend upon the structure and the configuration ofsolvand are attributed to different short-range interactions in the ground and excited states of the complexes. In analogy with other diastereomeric complexes, the phenomenological binding energy of the homochiral cluster is found to be greater than that of the heterochiral one. Preliminary measurements of excitation spectrum of(+)-(R)-1-Indanol(IR) is also reported.

scholarly journals Supramolecular architectures of 4-hydroxytetraphenylporphyrin with aza-donors

2014 ◽  
Vol 70 (a1) ◽  
pp. C554-C554 ◽  
Author(s):  
Purnendu Nandy ◽  
V. Pedireddi
Keyword(s):  
Three Dimensional ◽  
Molecular Complexes ◽  
Hydroxyl Groups ◽  
X Ray Diffraction ◽  
X Ray ◽  
Supramolecular Architectures ◽  
Detailed Structural Analysis ◽  
Different Types ◽  
Solvent Molecules ◽  
Molecular Adducts

Molecular adducts of 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin (1) with aza-donors like 4,4'-bipyridine (a), 1,2-bis(4-pyridyl)ethane (b), trans-1,2-bis(4-pyridyl)ethylene (c), 4,4'-trimethylene-dipyridine (d), phenazine (e), 1,10-phenanthroline (f), 1,7-phenanthroline (g) and 4,7-phenanthroline (h) have been prepared. All the molecular complexes are crystallized along with the solvent of crystallization, except in the complex with the aza-donor b. Detailed structural analysis of the obtained complexes has been carried out by single crystal X-ray diffraction. The three dimensional structures of the molecular adducts are facilitated by directional hydrogen bonding features of hydroxyl groups with aza donors as well as solvent molecules, leading to the formation of different types of supramolecular architectures like sheets, tapes, host-guest assembly etc. For example, in the complex of 1 and aza donor a, which crystallizes as a hydrate, the porphyrin molecules interact with water and 4,4'-bipyridine through O-H...O and O-H...N hydrogen bonds, which leads to the formation of molecular sheets in two dimensional arrangement. An important noteworthy observation is that the molecular complexes are crystalline even after removal of the solvents by heating, as characterized by thermogravimetric analysis (TGA) and powder X-ray diffraction (PXRD). Further, all the complexes are found to be fluorescence sensitive, perhaps due to the porphyrin molecules.

Limiting activity coefficients in dilute solutions of nonelectrolytes. II. Determination for polar–nonpolar and polar–polar binary mixtures, and the application of some solubility-parameter treatments

1986 ◽  
Vol 64 (1) ◽  
pp. 198-203 ◽  
Author(s):  
Shapour Afrashtehfar ◽  
Genille C. B. Cave
Keyword(s):  
Binary Mixture ◽  
Activity Coefficients ◽  
Vapor Phase ◽  
Solubility Parameter ◽  
Chromatographic Analysis ◽  
Dipole Interaction ◽  
The Other ◽  
Binary Solutions ◽  
Polar Components ◽  
Induced Dipole

Activity coefficients were determined at 293.15 K for the more dilute component in 24 binary solutions of nonelectrolytes, by gas-chromatographic analysis of the equilibrium vapor phase. One component of the binary mixture was either nitromethane, nitroethane, 1-nitropropane, 2-nitropropane, ethanenitrile, propanenitrile, ethyl ethanoate, or butyl ethanoate; and the other component was either heptane, 1-heptene, or 1,6-heptadiene.From the limiting activity coefficients of these components, some factors that affected their magnitude were identified. The values were also used to test the modifications of Prausnitz, Blanks, and Weimer, of Helpinstill and Van Winkle, and of Keller, Karger, and Snyder to the Scatchard–Hildebrand equation modified to accommodate polar components. In addition, the degree of constancy of the ratio of the dipole – induced dipole interaction parameter for a series of solutes in one solvent to that in another was considered.

How many solvent molecules are required to solvate chiral 1,2-diols with hydrogen bonding solvents? A VCD spectroscopic study

2020 ◽  
Vol 22 (3) ◽  
pp. 1525-1533 ◽  
Author(s):  
Luisa Weirich ◽  
Juliana Magalhães de Oliveira ◽  
Christian Merten
Keyword(s):  
Hydrogen Bonding ◽  
Spectroscopic Study ◽  
Spectroscopic Analysis ◽  
Model Systems ◽  
Solvent Interactions ◽  
Solvent Molecules

A VCD spectroscopic analysis of selected model systems for solute–solvent interactions of chiral diols with hydrogen bonding solvents DMSO and ACN.

Hypernetwork models based on random hypergraphs

2019 ◽  
Vol 30 (08) ◽  
pp. 1950052
Author(s):  
Feng Hu ◽  
Jin-Li Guo ◽  
Fa-Xu Li ◽  
Hai-Xing Zhao
Keyword(s):  
Field Theory ◽  
Mean Field Theory ◽  
Mean Field ◽  
World Systems ◽  
Uniform Hypergraphs ◽  
Different Types ◽  
Powerful Means ◽  
Simulation Results ◽  
Parameter Values ◽  
Random Hypergraphs

Hypernetworks are ubiquitous in real-world systems. They provide a powerful means of accurately depicting networks of different types of entity and will attract more attention from researchers in the future. Most previous hypernetwork research has been focused on the application and modeling of uniform hypernetworks, which are based on uniform hypergraphs. However, random hypernetworks are generally more common, therefore, it is useful to investigate the evolution mechanisms of random hypernetworks. In this paper, we construct three dynamic evolutional models of hypernetworks, namely the equal-probability random hypernetwork model, the Poisson-probability random hypernetwork model and the certain-probability random hypernetwork model. Furthermore, we analyze the hyperdegree distributions of the three models with mean-field theory, and we simulate each model numerically with different parameter values. The simulation results agree well with the results of our theoretical analysis, and the findings indicate that our models could help understand the structure and evolution mechanisms of real systems.

scholarly journals Synthesis, characterization and structure of the Bis(methyl-cyclopentadienyl)vanadium(IV) carboxylates

2005 ◽  
Vol 3 (1) ◽  
pp. 157-168 ◽  
Author(s):  
Jaromír Vinklarek ◽  
Jan Honzíĉek ◽  
Ivana Císařová ◽  
Martin Pavliŝta ◽  
Jana Holubová
Keyword(s):  
Aqueous Solution ◽  
Single Crystal ◽  
Diffraction Analysis ◽  
Carboxylic Acids ◽  
X Ray Diffraction ◽  
Monocarboxylic Acids ◽  
X Ray ◽  
Different Types ◽  
Chelate Compounds ◽  
Parameter Values

AbstractThe 1,1’-dimethylvanadocene dichloride ((C5H4CH3)2VCl2) reacts in aqueous solution with various carboxylic acids giving two different types of complexes. The 1,1’-dimethylvanadocene complexes of monocarboxylic acids (C5H4CH3)2V(OOCR)2 (R=H,CCl3, CF3, C6H5) contain two monodentate carboxylic ligands, whereas oxalic and malonic acids act as chelate compounds of the formula (C5H4CH3)2V(OOC-A-COO) (A=−, CH2). The structure of the (C5H4CH3)2 V(OOCCF3)2 complex was determined by single crystal X-ray diffraction analysis. The isotropic and anisotropic EPR spectra of all the complexes prepared were recorded. The obtained EPR parameter values were found to be in agreement with proposed structures.

scholarly journals Easy-hard phase transition in parameter estimation for optical waveguides

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Gunnar Claussen ◽  
Alexander K. Hartmann
Keyword(s):  
Phase Transition ◽  
Optical Waveguides ◽  
Energy Landscape ◽  
Global Optimum ◽  
Local Minima ◽  
Different Types ◽  
Two Phases ◽  
Parameter Values ◽  
Monochromatic Illumination

Abstract The determination of the parameters of cylindrical optical waveguides, e.g. the diameters $$\vec {d}=(d_1,\ldots ,d_r)$$ d → = ( d 1 , … , d r ) of r layers of (semi-) transparent optical fibres, can be executed by inverse evaluation of the scattering intensities that emerge under monochromatic illumination. The inverse problem can be solved by optimising the mismatch $$R(\vec {d})$$ R ( d → ) between the measured and simulated scattering patterns. The global optimum corresponds to the correct parameter values. The mismatch $$R(\vec {d})$$ R ( d → ) can be seen as an energy landscape as a function of the diameters. In this work, we study the structure of the energy landscape for different values of the complex refractive indices $$\vec {n}$$ n → , for $$r=1$$ r = 1 and $$r=2$$ r = 2 layers. We find that for both values of r, depending on the values of $$\vec {n}$$ n → , two very different types of energy landscapes exist, respectively. One type is dominated by one global minimum and the other type exhibits a multitude of local minima. From an algorithmic viewpoint, this corresponds to easy and hard phases, respectively. Our results indicate that the two phases are separated by sharp phase-transition lines and that the shape of these lines can be described by one “critical” exponent b, which depends slightly on r. Interestingly, the same exponent also describes the dependence of the number of local minima on the diameters. Thus, our findings are comparable to previous theoretical studies on easy-hard transitions in basic combinatorial optimisation or decision problems like Travelling Salesperson and Satisfiability. To our knowledge our results are the first indicating the existence of easy-hard transitions for a real-world optimisation problem of technological relevance.

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