Regioselective synthesis, stereochemical structure, spectroscopic characterization and geometry optimization of dispiro[3H-indole-3,2′-pyrrolidine-3′,3″-piperidines]

Synthesis and 2D-QSAR Study of Active Benzofuran-Based Vasodilators

“…Convergence to a local minimum was achieved when the energy gradient was ≤0.01 kcal/mol. The Restricted Hartree–Fock (RHF) method was used in spin-pairing for the two semiempirical tools [ 39 , 40 , 41 , 42 , 43 , 44 ]. The resulting output files were exported to CODESSA PRO that includes MOPAC capability for final geometry optimization.…”

Novel antibacterial active quinolone–fluoroquinolone conjugates and 2D-QSAR studies

“…The RHF (Restricted Hartree-Fock) method was used in spin pairing for the semi-empirical tools. [32][33][34][35][36][37][38][39][40][41] The resulting output files were exported to CODESSA-Pro that include MOPAC capability for final geometry optimization. CODESSA-Pro calculated 632 molecular descriptors including constitutional, topological, geometrical, charge-related, semi-empirical, molecular-type, atomic-type and bond-type descriptors for the exported 26 antibacterial active compounds (S1-S4, 10a-f, 11a-f, 13a-f and 14a-f).…”

Synthesis and DFT studies of an antitumor active spiro-oxindole

“…Convergence to a local minimum was achieved when the energy gradient was ≤ 0.01 kcal mol -1 . The RHF (Restricted Hartree-Fock) method was used in the spin pairing for the two semi-empirical tools24 (Figures S6, S7of the supplementary material exhibit the optimized structure of compound 7 by AM1 and PM3 methods, respectively). Additionally, the molecular structure of 7 in the ground state (in vacuo)…”

“…In the theoretical optimized structures (AM1, PM3 and DFT) for compound 7, this fragment pointing almost in opposite direction to that of the X-ray structure, as it is apparent from the values of the torsion angle C4-N1-C5-N2: AM1 (68.49°), PM3 (60.03°), and DFT (66.63°), and from X-ray data (-72.81°). This, most likely, can be attributed to the effect of crystal lattice affecting conformation of 7 in solid state, versus gas phase that is used in AM1, PM3, or DFT calculation methods 24,32. …”

“…Low HOMO-LUMO energy gap implies low molecular stability in the sense of its high reactivity in chemical reactions. The energy gap between HOMO and LUMOindicates also high kinetic stability, high excitation energies for many of the excited states, and large chemical hardness of the molecule in terms of its nucleophilicity and electrophilicity 24. …”