Jelena Đurđević
University of Kragujevac
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Featured researches published by Jelena Đurđević.
Journal of Physical Chemistry A | 2010
Alexandru T. Balaban; Jelena Đurđević; Ivan Gutman; Svetlana Jeremić; Slavko Radenković
Local aromaticity in rings of conjugated hydrocarbons can be measured in a variety of ways. In the present paper, we concentrate on two of these, namely, EC, i.e., the pi-electron content or pi-electron partition, and ef, the energy effect of cycles. For the central ring in five bipartite conjugated hydrocarbons (anthracene, triphenylene, perylene, coronene, and biphenylene), it was found that EC and ef values are modified in a consistent and predictable manner by annelation with benzenoid rings. Equations are presented for computing EC and ef values for the central ring in terms of three integers representing the numbers of annelated benzenoid rings (A, L, and G for angular, linear, and geminal annelation, respectively). The coefficients of A and G are positive (A > G) and the coefficient of L is negative for benzenoids, but for biphenylene, the situation is reversed for coefficients in the correlation for ef values.
Journal of Molecular Modeling | 2011
Svetlana Marković; Jelena Đurđević; Svetlana Jeremić; Ivan Gutman
AbstractThree fluoranthenes and one substituted fluoranthene, 2,2-dimethyl-2H-dibenzo[cd,k]fluoranthene, were investigated using the unrestricted symmetry-broken and complete active space methods. It was shown that four Kekuléan hydrocarbons are diradicals, implying that their ground state is a triplet. In the energetically less favorable singlet state these hydrocarbons exhibit pronounced diradical character. This occurance is explained with the tendency of the investigated molecules to delocalize their π-electrons. This leads to aromatic stabilization which is stronger than destabilization due to unpaired electrons. Our results for 2,2-dimethyl-2H-dibenzo[cd,k]fluoranthene are in excellent accord with experimental findings of McMaster et al. concerning this compound. FigureSpin density map of a triplet fluoranthene
Polycyclic Aromatic Compounds | 2009
Jelena Đurđević; Ivan Gutman; Julijana Terzić; Alexandru T. Balaban
Continuing our investigations of π -electron properties of fluoranthene-type polycyclic conjugated compounds [Gutman, Đurđević, Balaban, Polycyclic Aromatic Compounds 29 (2009): 3–11], we studied the energy effects of individual rings in fluoranthene and its catacondensed benzo-derivatives (i.e., benzo-annelated fluoranthenes possessing exactly one internal carbon atom). A number of general regularities were observed: (a) the PCP effect (six-membered rings connected by a single bond to the five-membered ring increase in it the intensity of cyclic conjugation), (b), the retro-PCP effect (the five-membered ring increases the intensity of cyclic conjugation in the six-membered rings to which it is connected by a single bond), (c) the linear effect (six-membered rings, linearly annelated to fluoranthene, decrease the cyclic conjugation in the five-membered ring), (d) the magnitude of the PCP effect differs, depending on whether the six-membered ring belongs to the “male” or “female” benzenoid fragment, and (e) the pattern of cyclic conjugationin of isoarithmic benzofluoranthenes is essentially identical.
Polycyclic Aromatic Compounds | 2009
Alexandru T. Balaban; Jelena Đurđević; Ivan Gutman
Cyclic conjugation in corannulene and its benzo-derivatives is studied by means of the π-electron contents and the energy effects of individual rings, with particular attention to the structural effects influencing the magnitude of cyclic conjugation in the 5-membered ring. Two main general regularities were observed: (a) the PCP effect (6-membered rings connected by a single bond to the 5-membered ring increase in it the intensity of cyclic conjugation), and (b), the linear effect (6-membered rings separated from the 5-membered ring by another 6-membered ring, but not in PCP constellation, decrease the magnitude of cyclic conjugation in the 5-membered ring).
Polycyclic Aromatic Compounds | 2006
Sabina Gojak; Slavko Radenković; Radmila Kovačević; Sonja Stanković; Jelena Đurđević; Ivan Gutman
It is shown that there is a remarkable difference between the Kekulé- and Clar-structure-dependence of the total π-electron energy (E) of catafusenes and perifusenes (catacondensed and pericondensed benzenoid molecules). Within classes of isomeric catafusenes the main parameter determining E is the Kekulé structure count whereas the influence of Clar-structure-based features is negligible. Within classes of isomeric perifusenes, Clar-structure-based features, in addition to the Kekulé structures, exhibit a significant effect on E. The present analysis is performed by using the mathematical formalism of the Zhang-Zhang polynomial [whose details are found in the recent paper: Gutman, Furtula, Balaban, Polycyclic Aromatic Compounds 26 (2006) 17–35].
Polycyclic Aromatic Compounds | 2011
Alexandru T. Balaban; Ivan Gutman; Svetlana Marković; Dušica Simijonović; Jelena Đurđević
The effects of benzo- and benzocyclobutadieno-(BCBD-)annelation on the local aromaticity of the central ring (X) of phenanthrene were examined. The local aromaticity of the ring X was estimated using a graph-theory-based index and two geometry-based indices. DFT calculations of phenanthrene congeners showed that many of these molecules are nonplanar, with significant steric strain. All three indices indicate that the effect of benzo-annelation is opposite to that of BCBD-annelation. The deviation of some phenanthrene derivatives from planarity does not influence the effects of annelation. This finding is in accord with some previously reported studies on the dependence of the aromaticity of the ring(s) on distortion from planarity.
Polycyclic Aromatic Compounds | 2012
Damir Vukičević; Jelena Đurđević; Ivan Gutman
It is shown that Kekulé structures do not realistically predict the behavior of π-electron properties of those polycyclic hydrocarbons that have many fixed double bonds. This is caused by the fact that such molecules would be destabilized by delocalization. We analyze a group of polycyclic hydrocarbons with a large number of fixed bonds, whose geometry was determined by means of an unrestricted symmetry-broken UB3LYP/6-311G(d,p) DFT method. We put forward a new concept, the unpaired bond order, and show that it is well correlated with bond lengths, but poorly correlated with Pauling bond orders. Hence, in this way we provide a simple test of the validity of the Pauling-bond-order concept for the molecule being considered.
Monatshefte Fur Chemie | 2014
Slavko Radenković; Marija Antić; Jelena Đurđević; Svetlana Jeremić
A detailed electronic structure study of singlet and triplet states of a series of biradicaloid pleiadene-like molecules was performed using the DFT and complete active space methods. It was shown that the singlet–triplet gaps obtained with the B3LYP, B2PLYP, and CASSCF methods are not a monotone function of the number of annelated benzene rings. According to the CASSCF results, 9,10-naphthopleiadene is a triplet biradical, whereas all other members of the series are found to be singlet biradicaloids exhibiting very pronounced biradical character. On the other hand, the B2PLYP calculations revealed that 9,10-anthracenopleiadene is a triplet biradical molecule. A detailed analysis of the local aromaticity of singlet and triplet states of the examined molecules was done by means of the multi-centre delocalization indices, harmonic oscillator model of aromaticity index, and nucleus independent chemical shifts. It was shown that the triplet states are more aromatic than the corresponding singlet electronic states. The difference in aromaticity of the singlet and triplet electronic states becomes smaller along the series of benzannelated pleiadenes. The more pronounced aromatic character of the triplet states can compensate the instability coming from the presence of unpaired electrons, which can explain the fact that the mid-size members of the examined series are found to be triplet biradicals.Graphical abstract
Chemical Physics Letters | 2009
Slavko Radenković; Jelena Đurđević; Ivan Gutman
Monatshefte Fur Chemie | 2009
Jelena Đurđević; Slavko Radenković; Ivan Gutman; Svetlana Marković