Theoretical study of molecular and electronic structure of 2‐Se‐(2‐methyl‐2‐propenyl)‐1‐benzoic acid

Abstract

A theoretical study of 2-Se-(2-methyl-2-propenyl)-1-benzoic acid was carried out to investigate the molecular and electronic structure of this molecule, using the B3LYP density functional theory (DFT) method with the 6-311ϩG** basis set. The optimized geometry of the molecule was obtained for the ortho, meta, and para isomers of the complex. In addition, the theoretical vibrational spectrum is presented, and thermal corrections in the limit of 100 -1,000 K are discussed using the Shomate thermodynamic equations.

Theoretical investigation of the electronic structure of 1-(3,4; 3,5 and 3,6-bis-selenocyanato-phenyl) pyrrolidinofullerenes

“…It is interesting to note that while in the ortho isomer the Se-Se interaction causes the 77 Se shifts to lower, the Se-N interaction in the para structure is stronger as can be seen by the slightly lower shift (by $3 ppm). This supports our initial assertion of strong Se interactions with electronegative atoms [26]. Table 2 has the HOMO/LUMO gaps, total energies, relative energies and corrected enthalpy differences.…”

“…In this structure we see that the Se-Se distance (orange spheres in the figure) is $3.2 Å , with a bond order between them of approximately 0.004. Interestingly, this is very similar to the Se-O bond order in ortho 2-Se-(2-methyl-2-propenyl)-1-benzoic acid [26] where the distance was 3.21 Å with a bond order of 0.0005. In the para and meta isomers the Se-Se distances are 5.8 and 6.6 Å , respectively.…”

“…As in previous Se systems [26], the ability of Se to mediate charge on the molecule (as were calculated by observing the charges and electrostatic potentials for this system) may allow for it to have a crucial role in various biochemical mechanisms. This fact, can in turn allow for molecular stabilization of free radicals and other excess charge that is the cause of DNA mutations and subsequently cancer.…”

“…Moreover, the ONIOM method [24] with the fullerene described using the UFF force-field [25] was used to compare geometries, energies and frequencies to the full DFT optimizations. In our recent investigations on similar Se containing systems [26] we have found that the DFT-B3LYP method is able to accurately predict experimental parameters [27].…”

Chalcanthrene–fullerene complexes: A theoretical study

“…For the S, S case we also obtain longer C-S bond lengths than in the O, S case as a consequence of ring puckering. In the O, Se case a the molecule is stabilized by chalcogenide interactions [21][22][23] which tend to stabilize complexes containing Se. The intermolecular separation is lower than in the S, S case and the bond angle distortions minimized.…”