Prof. Sonia Ilieva

CCS: Computational Chemistry & Spectroscopy

Head: S. Ilieva

The main research interests of the CCS laboratory are in the following fields:

ü  Computational organic chemistry: application of quantum mechanical computations for studying organic reaction mechanisms and resolving questions set from experiment; theoretical studies on the conformational stabilities of organic compounds.

ü  Physical organic chemistry: theoretical description of chemical reactivity by applying quantum mechanical methods and experimental kinetic measurements.

ü  Quantitative structure-activity relationship (QSAR) studies of biologically active organic compounds.

The electrostatic potential at nuclei (EPN) was proposed as a new index of reactivity in series of publications from the laboratory. It was demonstrated that the electrostatic potential at nuclei provides remarkable quantitative predictions of reaction rates for various charge-controlled organic reactions. The processes studied include solvolitic reactions of esters and amides, the SN2 reaction, proton transfer reactions, the electrophilic aromatic substitution. It was also shown that the index correlates quantitatively with the energies of hydrogen bond formation. A new theoretical quantity, electrophile affinity, was successfully applied in quantifying reactivity for SEAr reactions.

The mechanisms of the reactions considered were elucidated by detailed theoretical analysis. The origin of the SN2 benzylic effect was also elucidated. An efficient computational approach for the evaluation of substituent constants was developed. Theoretical quantum chemical computations were applied in answering a question set from the experiment and the diastereoselectivity of Michael addition to chalcones was rationalized and explained in terms of stability of the prereactive complexes formed.

An efficient computational approach for the evaluation of substituent constants was developed.

 

Future research directions

The research directions will be extended to cover interactions and processes of great biological relevance. These may include:

ü  The characterization of hydrogen bonding ability of different atomic sites in biological molecules.

ü  Continuation of the studies on the reaction mechanisms and reactivity for selected organic reactions.

ü  The mechanism of interaction between various ligands (potential medicines) and bioreceptors.

ü  Applications of the electrostatic potential at nuclei and other electronic parameters in describing properties of various nanosystems.

ü  Applications of theoretical quantum chemical computations in studying the mechanism of action of the enzymes with proteolitic activity exploring the dependence between chemical structure, electronic and vibrational spectra.

Selected publications

  1.        1.        B. Galabov, S. Ilieva, H. F. Schaefer III, “An efficient computational approach for the evaluation of substituent constants”, J. Org. Chem. 71 (2006) 6382.
  2.        2.        B. Galabov, S. Ilieva, B. Hadjieva, Y Atanasov, and H. F. Schaefer III, “Predicting Reactivities of Organic Molecules. Theoretical and Experimental Studies on the Aminolysis of Phenyl Acetates”, J. Phys. Chem. A 112 (2008) 6700.
  3.        3.        B. Galabov, V. Nikolova, J. J. Wilke, H. F. Schaefer III,W. D. Allen, “Origin of the SN2 Benzylic Effect”, J. Am. Chem. Soc. 130 (2008) 9887.
  4.        4.        D. Cheshmedzhieva, S. Ilieva, B. Hadjieva and B. Galabov, “The mechanism of alkaline hydrolysis of amides: a comparative computational and experimental study of the hydrolysis of N-methylacetamide, N-methylbenzamide, and acetanilide”, J. Phys. Org. Chem. 22 (2009) 619.
  5.        5.        D. Zhiryakova, I. Ivanov, S. Ilieva, M. Guncheva, B. Galunsky and N. Stambolieva, “Do N-terminal nucleophile hydrolases indeed have a single amino acid catalytic center?, FEBS Journal 276 (2009) 2589.
  6.        6.        G. Koleva, B. Galabov, J. Wu, H. F. Schaefer, P. v. R. Schleyer, “Electrophile Affinity: a Reactivity Measure for Aromatic Substitution”, J. Am. Chem. Soc. 131 (2009) 14722.