Theoretical characterization and biological activity investigation of indirubins, cyclin dependent kinases inhibitors.

Up to now, significant research efforts have been directed towards investigating indirubin and its derivatives as potential candidates for developing new compounds with multiple biological activities. In the present work, natural indirubin and numerous of its chemical derivatives referred to as indirubins have been investigated computationally using DFT method with the B3LYP/6-311 + G(d,p) level of theory, in order to reveal structure- biological activity relationship. We started with a structural properties description.

Rationalizing Aggregate Structures with Orbital Contributions to the Exchange-Repulsion Energy.

It is shown that repulsive interactions have a crucial influence on the structure of prototypical non-covalently bonded systems. To explain this, we propose a molecular orbital-based model for the exchange-repulsion contribution to the total interaction energy. As a central result, our model shows that energetically preferred aggregate structures frequently exhibit reduced exchange repulsion, which can be deduced from the nodal structure of certain occupied orbitals.

Theoretical Study on Non-Linear Optics Properties of Polycyclic Aromatic Hydrocarbons and the Effect of Their Intercalation with Carbon Nanotubes.

Results of a theoretical study devoted to comparing NLO (non-linear optics) responses of derivatives of tetracene, isochrysene, and pyrene are reported. The static hyperpolarizability β, the dipole moment μ, the HOMO and LUMO orbitals, and their energy gap were calculated using the CAM-B3LYP density functional combined with the cc-pVDZ basis set. The para-disubstituted NO-tetracene-N(CH) has the highest NLO response, which is related to a large intramolecular charge transfer.

DFT evaluation of structural, electronic and variation properties for complex carbohydrates with biological interest.

The synthetic bicyclic bis(hemiacetals) compounds 1,5-pyranose-9,7-pyranoses, with a structural analogy to the bicyclic monosaccharide Bradyrhizose, have been described here based on a theoretical approach, using DFT calculations with the B3LYP functional combined with the 6-311 + G(d,p) basis set. First, we have performed a geometrical and electronic properties description of (1 R,9S), (1S,9S) and (1S,9R)-1,5-pyranose-9,7-pyranoses. Results analysis indicated that, slight differences in the three-dimensional orientations of their atoms lead to an enormous difference in chemical reactivity.

Testing the CP-correction procedure with different DFT methods on H-bonding complexes of κ-carrabiose with water molecules.

Interaction of water molecules with κ-carrabiose disaccharide, within three H-bonding complexes, was investigated. Particular interest was focused on the way with which the BSSE correction has to be performed. Two strategies were used, either performing BSSE correction during or after optimization.