scholarly journals An Increment System to Predict the Effect of Different London Dispersion Donors in all‐meta Substituted Azobenzenes

Author(s):  
Chiara Di Berardino ◽  
Marcel A. Strauss ◽  
Dominic Schatz ◽  
Hermann Andreas Wegner
Keyword(s):  
2017 ◽  
Vol 139 (46) ◽  
pp. 16696-16707 ◽  
Author(s):  
Andrey A. Fokin ◽  
Tatyana S. Zhuk ◽  
Sebastian Blomeyer ◽  
Cristóbal Pérez ◽  
Lesya V. Chernish ◽  
...  

2021 ◽  
Author(s):  
carmelo Naim ◽  
Frédéric Castet ◽  
Eduard Matito

<div> <div> <div> <p>The geometrical structures, relative Z-E energies, and second-order nonlinear responses of a collection of azobenzene molecules symmetrically substituted in meta- position with functional groups of different bulkiness are investigated using various ab initio and DFT levels of approximation. We show that RI-MP2 and RI-CC2 approximations provide very similar geometries and relative energies and evidence that London dispersion interactions existing between bulky meta-substituents stabilize the Z con- former. The !B97-X-D exchange-correlation functional provides an accurate description of these effects and gives a good account of the nonlinear optical response of the molecules. We show that density functional approximations should include no less than 50% of Hartree-Fock exchange to provide accurate hyperpolarizabilities. A property-structure analysis of the azobenzene derivatives reveals that the main contribution to the first hyperpolarizability comes from the azo bond, but phenyl meso-substituents can enhance it.</p> </div> </div> </div>


2014 ◽  
Vol 1619 ◽  
Author(s):  
Daniel M. Dryden ◽  
Yingfang Ma ◽  
Jacob Schimelman ◽  
Diana Acosta ◽  
Lijia Liu ◽  
...  

ABSTRACTThe optical properties and electronic structure of AlPO4, SiO2, Type I collagen, and DNA were examined to gain insight into the van der Waals-London dispersion behavior of these materials. Interband optical properties of AlPO4 and SiO2 were derived from vacuum ultraviolet spectroscopy and spectroscopic ellipsometry, and showed a strong dependence on the crystals’ constituent tetrahedral units, with strong implications for the role of phosphate groups in biological materials. The UV-Vis decadic molar absorption of four DNA oligonucleotides was measured, and showed a strong dependence on composition and stacking sequence. A film of Type I collagen was studied using spectroscopic ellipsometry, and showed a characteristic shoulder in the fundamental absorption edge at 6.05 eV. Ab initio calculations based on density functional theory corroborated the experimental results and provided further insights into the electronic structures, interband transitions and vdW-Ld interaction potentials for these materials.


Author(s):  
Yoshiharu Nishiyama

The contribution of hydrogen bonds and the London dispersion force in the cohesion of cellulose is discussed in the light of the structure, spectroscopic data, empirical molecular-modelling parameters and thermodynamics data of analogue molecules. The hydrogen bond of cellulose is mainly electrostatic, and the stabilization energy in cellulose for each hydrogen bond is estimated to be between 17 and 30 kJ mol −1 . On average, hydroxyl groups of cellulose form hydrogen bonds comparable to those of other simple alcohols. The London dispersion interaction may be estimated from empirical attraction terms in molecular modelling by simple integration over all components. Although this interaction extends to relatively large distances in colloidal systems, the short-range interaction is dominant for the cohesion of cellulose and is equivalent to a compression of 3 GPa. Trends of heat of vaporization of alkyl alcohols and alkanes suggests a stabilization by such hydroxyl group hydrogen bonding to be of the order of 24 kJ mol −1 , whereas the London dispersion force contributes about 0.41 kJ mol −1  Da −1 . The simple arithmetic sum of the energy is consistent with the experimental enthalpy of sublimation of small sugars, where the main part of the cohesive energy comes from hydrogen bonds. For cellulose, because of the reduced number of hydroxyl groups, the London dispersion force provides the main contribution to intermolecular cohesion. This article is part of a discussion meeting issue ‘New horizons for cellulose nanotechnology’.


2019 ◽  
Vol 21 (22) ◽  
pp. 11569-11577 ◽  
Author(s):  
Qing Lu ◽  
Frank Neese ◽  
Giovanni Bistoni

The coupled-cluster-based local energy decomposition (LED) analysis is used to elucidate the nature of the TM–alkane interaction in alkane σ-complexes.


1968 ◽  
Vol 23 (7) ◽  
pp. 979-984 ◽  
Author(s):  
Manlio Sanesi ◽  
Vittoriano Wagner

The heats of adsorption on weakly activated γ-aluminium oxide for a number of linear alkanes (from n-butane to n-nonane) and for 2.2.4-trimethylpentane have been determined by GSC and extrapolated to zero surface coverage.The dependance of the adsorption energy on the number of carbon atoms is discussed on the basis of the bidimensional gas model: it is shown that the interactions of the adsorbates with the oxidic surface are mainly due to London dispersion forces.


1952 ◽  
Vol 20 (11) ◽  
pp. 1812-1812 ◽  
Author(s):  
James F. Hornig ◽  
Joseph O. Hirschfelder

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