The main interaction between pyridine and zeolites leads to form a hydrogen bond between the N atom of pyridine and OH groups of zeolites. The present work reports a theoretical study about the structural, vibrational and topological properties of the charge distribution of the molecular complexes between pyridine and a series of acids sites of zeolites. The calculated structural parameters...

In molecular mechanics (MM) studies, atom types and/or bond types of molecules are needed to determine prior to energy calculations. We present here an automatic algorithm of perceiving atom types that are defined in a description table, and an automatic algorithm of assigning bond types just based on atomic connectivity. The algorithms have been implemented in a new module of the AMBER package...

In this paper the behavior of three well-known electron-sharing indexes, namely, the AIM delocalization index and the Mayer and fuzzy atom bond orders are studied at the Hartree-Fock level. A large number of five-membered ring molecules, containing several types of bonding, constitute the training set chosen for such purpose. A detailed analysis of the results obtained shows that the three inde...

Graph theory had wide applications in developing silico tools and it is widely used to calculate topological indices establish structural activity relations of chemicals/compounds. However, usage Zagreb with respect natural compounds activity/toxicity prediction needs more attention. Many available online are using atom bond connectivity index (ABC Index), first second indices. The the Hyper ve...

In this research work, we studied theoretically the structural properties of (5H-tetrazol-1-yl)(triphenylphosphine)gold or [Au(tetz)(PPh3)] by density functional theory (DFT) method at LANL2DZ level. All calculations were performed at 298.15 K and 1 atmosphere. Firstly, the bond lengths, bond angles, dihedral angles and natural charge density on atoms of the compound were calculated. The depend...

A topological index is a numerical measure that characterises the whole structure of graph. Based on vertex degrees, idea an atom-bond connectivity A B C was introduced in chemical graph theory. Later, different versions ABC were crea...

The connectivity index chi can be regarded as the sum of bond contributions. In this article, boiling point (bp)-oriented contributions for each kind of bond are obtained by decomposing the connectivity indices into ten connectivity character bases and then doing a linear regression between bps and the bases. From the comparison of bp-oriented contributions with the contributions assigned by ch...

A series of structurally related 2,4-dioxopyrimidine-1-carboxamide derivatives as highly potent inhibitors against acid ceramidase were subjected to hologram quantitative structure-activity relationship (HQSAR) analysis. A training set containing 24 compounds served to establish the HQSAR model. The best HQSAR model was generated using atoms, bond, connectivity, donor and acceptor as fragment d...

A series of structurally related 2,4-dioxopyrimidine-1-carboxamide derivatives as highly potent inhibitors against acid ceramidase were subjected to hologram quantitative structure-activity relationship (HQSAR) analysis. A training set containing 24 compounds served to establish the HQSAR model. The best HQSAR model was generated using atoms, bond, connectivity, donor and acceptor as fragment d...

Entropy is essential. a measure of system’s molecular disorder or unpredictability, since work produced by organized motion. theory offers profound understanding the direction spontaneous change for many commonplace events. A formal definition random graph exists. It deals with relational data’s probabilistic and structural properties. The lower-order distribution an ensemble attributed graphs ...