engleski

Optimization, interpretation, and selection of molecular descriptors in structure-property models

In development of novel structural descriptors different optimization procedures can be applied, in order to improve their relevance and descriptive potential in establishing structure-property/activity models. Examples of commonly-used optimizations are those based on finding or definition of different weighting schemes (or methods) for calculating charges or electronegativites of atoms, or different bond weighting schemes. One such example is also the optimization of molecular connectivity index (of order one) introduced by Randić in 1975 [1], also named the product-connectivity index, which is a distance-based topological index belonging to the class of Zagreb indices introduced by Gutman and Trinajstić in 1972 [2]. Recently, Gutman reviewed twenty formulations of connectivity index that are based on different weighting schemes of vertex degrees (representing C atom valence counting only neighbouring C atoms), and compared them in modelling the standard heats of formation and normal boiling points of acyclic octanes. I will analyze some novel procedures for optimization of connectivity index in an attempt to (1) improve physico-chemical interpretation of connectivity index as a molecular descriptor, (2) test and improve the quality of different formulations of connectivity index in estimation and prediction of several properties of larger sets of alkanes, and (3) compare the quality of these relationships with the best ones obtained using the large pool of descriptors calculated by the computer program Dragon [4]. Based on these three criteria, suggestions for the selection of proper optimization procedure in the use of connectivity indices in structure-property/activity modelling will be given. References: [1] M. Randić, J. Am. Chem. Soc. 97 (1975) 6606– 6615. [2] Gutman, I. ; Trinajstić, N. Chem. Phys. Lett., 17 (1972) 535-538. [3] Gutman, I, Croat. Chem. Acta. 86 (2013) 351– 361. [4] Dragon program, Talete srl, Milano, Italy (http://www.talete.mi.it/products/dragon_descripti on.htm)

structure-property model, optimization, descriptor selection, validation, molecular connectivity index

MZO-Croatia - basic grant