PHYSICAL ORGANIC & COMPUTATIONAL CHEMISTRY
First row (left to right, seated): Valentin Monev, Nadya Tabakova, I. Pojarlieff, Milena Spassova, Stefan Stanchev
Second row: Assen Koedjikov, Jose Kaneti, Martin Gotsev, Martin Kotev, Petko M. Ivanov
kinetics, ab initio MO calculations, molecular
mechanics, conformational analysis, reactivity, mechanisms, molecular design
Ivan G. Pojarlieff, Professor Emeritus, Dr.Sci., BAS Corr. member
Main Research Topics
- Kinetics and thermodynamics of reactions in solution,
general acid-base catalysis.
- Mechanism of organic reactions, sterically strained
models of biorganic reactions
- Quantitative correlation of reactivity, steric effects in
- Organic synthesis
- Reactions in organized media
- Ab initio MO and DFT studies of molecular structure, reactivity
and reaction mechanisms, molecular design
- Computational conformational analysis, modelling
structure and dynamics of organic molecules
- One of the main research projects of the laboratory has
centered on bioorganic models particularly of biotin
mediated acyl transfers. Sterically strained substrates
by means of the gem-dimethyl effect bring about rate
enhancements up to six powers of ten thus allowing model
reactions to be studied under mild conditions where
biologically relevant mechanisms such as general
acid-base catalysis can be studied. One early result
showed the importance in the transition state of proton
transfer to the carbonyl oxygen in N-acylation of urea by
carboxylate. Recent work has unraveled the intricate
interactions of the gem-dimethyl effect and steric
hindrance to proton transfer which cause unexpected
changes of mechanism and reactivity in cyclizations of
hydantoic esters and amides.
- The above studies have been expanded to micellar systems
providing understanding of the effect of
microenvironment. Micelles with reactive counterions are
of particular interest, in identifying specific effects
of buffer concentration in micellar media. General base
catalysis at the micellar interface is favoured by about
two orders of magnitude over the specific base catalysis.
A rigorous pseudophase treatment has been proposed for
the water-promoted reaction of bromine and 1-octene in
- Another direction of research is computational
conformational analysis: new parameterizations for
molecular mechanics force fields have been developed for
modeling dicarboxylic anhydrides, cyclopropanes,
compounds with phenyl groups on neighbouring carbon
atoms. MM study of the gem-dimethyl effect and steric
effects in acyl transfers involving stereoelectronic
effects should be mentioned. Computational protocols have
been tested for the modeling and the MD simulation of the
inclusion processes of small organic molecules with
macrocycles. Algorithms and software have been developed
for the molecular mechanics modeling of molecular
crystals with full geometry optimization of the reference
- DFT and ab initio MO, including multiconfiguration and multireference, studies of molecular structure, spectra,
ground and excited states, and reaction mechanisms: transition metals,
concerted cycloadditions, e.g. of anhydrides to Schiff bases, Diels - Alder
stereoselectivity and catalysis; phosphorus reaction mechanisms. Enzyme and supramolecular modelling.
Computational design of drugs, fluorescent dyes and other optoelectronic materials.
Selected publications from the laboratory
- Quantitatiive evaluation of the gem-dimethyl effect on
the succinic acid - anhydride equilibria. Conformations
of the acids and anhydrides by empirical force-field
calculations. P. M. Ivanov and I. G. Pojarlieff, J. Chem.
Soc., Perkin Trans., 2, (1984) 245.
- Intramolecular nucleophilic attack on carboxylate by
ureide anion. General acid-base catalysis of the alkaline
cyclization of 2,2,3,5-tetramethylhydantoic acid. I. B.
Blagoeva, I. G. Pojarlieff and A. J. Kirby, J. Chem.
Soc., Perkin Trans., 2, (1984) 745
- Leffler relationship of the gem-dimethyl effect. I. B.
Blagoeva and I. G. Pojarlieff and V. T. Rachina, J. Chem.
Soc., Chem. Comm., (1986) 946.
- General Acid-Base Catalysed Cyclisation Reactions of a
Strained omega-Phenylhydantoic Acid. I. Blagoeva,
J.Chem.Soc. Perkin Trans. 2, (1987), 127-134.
- Pseudophase Model for Reactivity in Reverse Micelles. The
Case of the Water Promoted Reaction between Two
Lipophilic Reagents, Bromine and 1-Octene, in AOT
Microemulsions. I.B.Blagoeva, P.Gray, M.F.Ruasse,
J.Phys.Chem., 100 (1996), 12638.
- Computational Study on the Ring Distortions of
1,4-Dicyanobenzene in the Gas Phase and in the Crystal,
P. M. Ivanov, J. Mol. Struct., 440 (1998) 237-246.
- 1H NMR Spectra and Structure of Safranines. Hindered
Rotation of the Dialkylamino Group in Azo Derivatives,
L.I. Proevska and I.G. Pojarlieff, Dyes and Pigments, 36
- On the disappearance of the gem-dimethyl effect in the
base-catalysed cyclization of ethyl hydantoates. Ergun
Atay, Iva B. Blagoeva, Anthony J. Kirby and Ivan G.
Pojarlieff, J. Chem. Soc., Perkin Trans. 2, (1998)
- A CAS SCF Study of the Reaction Mechanism of the Alpha-Alkynone Rearrangement,
J. Kaneti, Helv. Chim. Acta 2000, 83/4, 836-842.
- Fluorinated Alcohols Enable Olefin Epoxidation by H2O2: Template Catalysis,
S. P. de Visser, Jose Kaneti, R. Neumann, S. Shaik: J. Org. Chem. 2003, 68(7), 2903-2912.
- Schiff Base Addition to Cyclic Carboxylic Anhydrides - an Unusual Concerted Reaction.
A MO and DFT Theoretical Study: J. Kaneti, S. Bakalova, and I. Pojarlieff, J. Org. Chem.,
2003, 68(17), pp. 6824-6827.
- Electronic Absorption and Emission Spectra and Computational Studies of Some 2-Aryl, 2-Styryl, and 2-(4.-Aryl)Butadienyl Quinazolin-4-ones: S. Bakalova, A. Gil Santos, I. Timcheva, J. Kaneti, I. Filipova, G. Dobrikov, and V. D. Dimitrov, J. Mol. Struct. THEOCHEM 2004, 710(1-3), 229-234.
- Phenylacetyl arylamides as probes for the stereoselectivity of penicillin acylase from E.coli. Kinetic studies and molecular modelling: Maya Guncheva, Ivaylo Ivanov, Boris Galunsky, Nicolina Stambolieva,* and Jose Kaneti,* Eur. J. Biochem. 2004, 271(11), 2272-2279.
- Origins of Stereoselectivity in the Diels-Alder Addition of Chiral Hydroxyalkyl Vinyl Ketones to Cyclopentadiene: A Quantitative Computational Study, Snezhana M. Bakalova and Jose Kaneti, J. Phys. Chem. A, 2008, 112(50), 13006-13016.
- Design and Photophysical Properties of a New Molecule with a N-B-N Linked Chromophore: Snezhana Bakalova, Francisco Mendicuti, Obis Castano, and Jose Kaneti, Chemical Physics Letters 2009, 478, 206.210.
- M. K. Georgieva, F. J. S. Duarte, S. M. Bakalova, A. Gil Santos, 1,5-Disubstituted Pyrrolidines as Chiral Auxiliaries in Radical Reactions: A Theoretical Approach, European Journal of Organic Chemistry 2010, 4841-4850
- F. J. S. Duarte, S. M. Bakalova, E. J. Cabrita, A. Gil Santos, Lewis Acid Catalyzed Reactions of Chiral Imidazolidinones and Oxazolidinones: Insights on the Role of the Catalyst, Journal of Organic Chemistry 2011, 76(17), 6997 . 7004
- S. M. Bakalova, A. G. Santos, Diels-Alder Reactions of Chiral Isoimidium Salts: A Computational
Study, J. Org. Chem. 2014, 79, 8202-8211.
- S. Nenon, B. Champagne, M. I. Spassova, Assessing long-range corrected functionals with
physically-adjusted range-separated parameters for calculating the polarizability and the
second hyperpolarizability of polydiacetylene and polybutatriene chains. Phys. Chem. Chem. Phys. 2014, 16, 7083-7088.
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