István Lukovits

Corrosion Inhibitors—Correlation between Electronic Structure and Efficiency

Abstract Corrosion inhibition efficiencies of heterocyclic, unsaturated (aromatic and nonaromatic) compounds (pyrimidines, benzothiazole derivatives, amino acids containing an aromatic part, pyridi...

Extensions of the Wiener number

Particularly for structure−property correlations there are many chemical graph-theoretic indices, one of which is Wieners “path number”. Because Wieners original work focused on acyclic structure...

Nonlinear group-contribution models of corrosion inhibition

Abstract The correlation between the molecular structure and inhibitor efficiency (Ei) of triamines was investigated. The group-contribution approach was adapted to account for Langmuir- and Frumki...

LKP model of the inhibition mechanism of thiourea compounds

Abstract Interaction of corrosion inhibitors with metal surfaces in acidic solutions was investigated using a nonlinear model encompassing the Langmuir adsorption isotherm. A regression equation, w...

Polynomial model of the inhibition mechanism of thiourea derivatives

Interaction of corrosion inhibitors with metal surfaces in acidic solutions was modelled by using a polynomial model based on the Langmuir adsorption isotherm. The curve-fitting procedure yielded a regression equation with a multiple correlation coefficient equal to 0.982.

The use of the isokinetic relationship and molecular mechanics to investigate molecular interactions in inclusion complexes of cyclodextrins

Abstract The formation of 1:1 inclusion complexes of α- and β-cyclodextrin with various compounds in aqueous medium has been investigated for the isokinetic behavior. The included compounds fall clearly into definite groups, showing that the isokinetic behavior, when based on proper statistical methods, can be used as a tool for the interpretation and dissection of different interaction and reaction mechanisms in similar chemical reactions. Theoretical free energies, enthalpies and entropies of the formation of the inclusion complexes are calculated using the “rigid molecule approximation” of the molecular mechanics approach. The calculated results are in good agreement with the experimental values. The orientations of the embedded guest molecules in cyclodextrins obtained from the calculations are in agreement with experimental findings. The classification of the guest molecules can be explained in terms of different interaction energies.

Second-quantization-based perturbation theory for intermolecular interactions without basis set superposition error

Abstract A new formalism is proposed for calculating perturbation energy corrections for the case of two interacting molecules at any distance. Second-quantization formalism ensures that the wavefunctions are automatically properly antisymmetric. The approach is based on the recent “chemical Hamiltonian” method, permitting basis set superposition (counterpoise) errors to be excluded from the beginning. The zeroth-order wavefunctions are right eigenfunctions of the formally non-Hermitean unperturbed Hamiltonian appearing in this formalism, and the perturbational problem is handled by introducing a biorthogonal (reciprocal) basis set.

Polarity-Numbers of Cycle-Containing Structures

A heuristic approach was used to derive a new version of the polarity-number, proposed originally by Wiener for acyclic hydrocarbons. The new versions were used to demonstrate quantitative structure−property relationships in a series of acyclic and cycle-containing hydrocarbons.

TREES WITH EXTREMAL HYPER-WIENER INDEX : MATHEMATICAL BASIS AND CHEMICAL APPLICATIONS

Trees with minimal and maximal hyper-Wiener indices (WW) are determined:  Among n-vertex trees, minimum and maximum WW is achieved for the star-graph (Sn) and the path-graph (Pn), respectively. Since WW(Sn) is a quadratic polynomial in n,, whereas WW(Pn) is a quartic polynomial in n, the hyper-Wiener indices of all n-vertex trees assume values from a relatively narrow interval. Consequently, the hyper-Wiener index must have a very low isomer-discriminating power. This conclusion is corroborated by finding large families of trees, all members of which have equal WW-values.

On calculation of the detour index

An algorithm for the detection of the longest path between any two vertices of a graph was proposed. The method was used to calculate the detour index of fused bicyclic structures. Analytical formulas for the detour index of fused bicyclic structures were derived, and it was shown the these can only be third-order polynomials.