Intramolecular hypervalent interaction in the conjugate five-membered rings

The intramolecular hypervalent interaction between the electron abundant atomic centers X and Y belonging to the IV-VI groups and second and fourth periods has been computationally studied on a model quasi-cyclic conjugate five-membered ring system 9 using the CCSD/6-311+G** and DFT B3LYP/6-311+G** methods. Electronic and structural factors affecting the strength and geometrical characteristics of the hypervalent X←Y interaction were analyzed based on the quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses. The donor-acceptor n(Y)→σ*(XR) interaction has been shown to be the central factor correlating all important properties of the studied hypervalently bonded compounds 9.     

Intramolecular C-H···O hydrogen bonding in 1,4-dihydropyridine derivatives

The diastereotopy of the methylene protons at positions 2 and 6 in 1,4-dihydropiridine derivatives with various substituents has been investigated. NMR spectroscopy and quantum chemistry calculations show that the CH···O intramolecular hydrogen bond is one of the factors amplifying the chemical shift differences in the 1H-NMR spectra.     

Single molecule and single atom sensors for atomic resolution imaging of chemically complex surfaces

Individual Xe atoms as well as single CO and CH(4) molecules adsorbed at the tip apex of a scanning tunneling microscope (STM) function as microscopic force sensors that change the tunneling current in response to the forces acting from the surface. An STM equipped with any of these sensors is able to image the short-range Pauli repulsion and thus resolve the inner structure of large organic adsorbate molecules. Differences in the performance of the three studied sensors suggest that the sensor functionality can be tailored by tuning the interaction between the sensor particle and the STM tip.     

Modeling intermolecular interactions of physisorbed organic molecules using pair potential calculations

The understanding and control of epitaxial growth of organic thin films is of crucial importance in order to optimize the performance of future electronic devices. In particular, the start of the submonolayer growth plays an important role since it often determines the structure of the first layer and subsequently of the entire molecular film. We have investigated the structure formation of 3,4,9,10-perylene-tetracarboxylic dianhydride and copper-phthalocyanine molecules on Au(111) using pair-potential calculations based on van der Waals and electrostatic intermolecular interactions. The results are compared with the fundamental lateral structures known from experiment and an excellent agreement was found for these weakly interacting systems. Furthermore, the calculations are even suitable for chemisorptive adsorption as demonstrated for copper-phthalocyanine/Cu(111), if the influence of charge transfer between substrate and molecules is known and the corresponding charge redistribution in the molecules can be estimated. The calculations are of general applicability for molecular adsorbate systems which are dominated by electrostatic and van der Waals interaction.     

Feasibility study of power engineering secondary equipment protection methods from static electricity

The paper presents feasibility study of power engineering secondary equipment protection methods from static electricity basing on calculation and experimental procedure. Method was applied for newly constructed objects and modernized objects as well. The procedure includes calculation of expected electrostatic potential at human body considering environment characteristics (relative humidity, dimensions and electrophysical characteristics of flooring and footwear). Calculated potential was compared to acceptable value. Acceptable value represents immunity test level of secondary equipment (relay protection and automation, communication equipment, PCs) presented in standards [1], [2], [3], [4], [5]. In calculations electrostatic charging current density j₀ = 10 μA/m² was taken as in domestic applications. Calculation result analysis showed optimal methods to limit human electrostatic charge accumulation for designed objects and objects in operation.     

The dependence of 90Y sorption on nanodiamonds on sizes of their aggregates in water solutions

Journal of Radioanalytical and Nuclear Chemistry - Today nanomaterials, including carbon ones, considered to be promising radionuclide carriers for nuclear medicine. We previously determined that...     

Stability of radical-functionalized gold surfaces by self-assembly and on-surface chemistry

We have investigated the radical functionalization of gold surfaces with a derivative of the perchlorotriphenylmethyl (PTM) radical using two methods: by chemisorption from the radical solution and by on-surface chemical derivation from a precursor. We have investigated the obtained self-assembled monolayers by photon-energy dependent X-ray photoelectron spectroscopy. Our results show that the molecules were successfully anchored on the surfaces. We have used a robust method that can be applied to a variety of materials to assess the stability of the functionalized interface. The monolayers are characterized by air and X-ray beam stability unprecedented for films of organic radicals. Over very long X-ray beam exposure we observed a dynamic nature of the radical–Au complex. The results clearly indicate that (mono)layers of PTM radical derivatives have the necessary stability to withstand device applications.

We have investigated the radical functionalization of gold with a derivative of the perchlorotriphenylmethyl radical using two methods: by chemisorption from the radical solution and by on surface chemical derivation from a precursor.     

Nonlinear Beltrami equation

ABSTRACT

We introduce a nonlinear counterpart of the classical Beltrami equation and study the main features of its solutions. It involves directional dilatations connected with a priory fixed point and a class of mappings called ring Q-homeomorphisms with respect to p-module. We also establish some regularity properties of solutions to such equation and illustrate them by several examples.