Synthetic Strategy and Structure Characterization of a New [1,3]Thiazolo[3,2-b][1,2,4]Triazolium Cationic Surfactant

Here, we present a synthetic strategy to access a new [1,3]thiazolo[3,2-b][1,2,4]triazolium-based cationic surfactant via the use of proton-induced heterocyclization method for quaternization of a nitrogen atom. The two-step synthesis of 2-heptyl-6,6-dimethyl-3-phenyl-5,6-dihydro-3H-[1,3]thiazolo[3,2-b][1,2,4]triazol-7-ium perchlorate is described in details. The analysis of NMR spectra unequivocally proved the formation of the 1,3-thiazolinium ring upon cyclization reaction. PM7 semiempirical calculations testify to the similar electronic structure of the newly synthesized surfactant cation and 1-heptylpyridinium cation.

Investigating the Molecular Basis for the Selective Inhibition of Aldehyde Dehydrogenase 2 by the Isoflavonoid Daidzin

Background: ALDH-2 has been considered an important molecular target for the treatment of drug addiction due to its involvement in the metabolism of the neurotransmitter dopamine: however, the molecular basis for the selective inhibition of ALDH-2 versus ALDH-1 should be better investigated to enable a more pragmatic approach to the design of novel ALDH-2 selective inhibitors. Objective: In the present study, we investigated the molecular basis for the selective inhibition of ALDH-2 by the antioxidant isoflavonoid daidzin (IC50 = 0.15 μM) compared to isoform 1 of ALDH through molecular dynamics studies and semiempirical calculations of the enthalpy of interaction. Methods: The applied methodology consisted of performing the molecular docking of daidzin in the structures of ALDH-1 and ALDH-2 and submitting the lower energy complexes obtained to semiempirical calculations and dynamic molecular simulations. Results: Daidzin in complex with ALDH-2 presented directed and more specific interactions, resulting in stronger bonds in energetic terms and, therefore, in enthalpic gain. Moreover, the hydrophobic subunits of daidzin, in a conformationally more restricted environment (such as the catalytic site of ALDH-2), promote the better organization of the water molecules when immersed in the solvent, also resulting in an entropic gain. Conclusion: The molecular basis of selective inhibition of ALDH-2 by isoflavonoids and related compounds could be related to a more favorable equilibrium relationship between enthalpic and entropic features. The results described herein expand the available knowledge regarding the physiopathological and therapeutic mechanisms associated with drug addiction.

Molecular modeling analyses for polyvinylidene X (X=F, Cl, Br and I)

Polyvinylidene (PVDF) substituted with different halogens (F, Cl, Br and I) has been studied theoretically by performing some semiempirical calculations at PM3 to obtain some physical parameters and improve the electronic properties. As a result of substitution bond length increases from 1.1083 Ǻ to 1.9921 Ǻ; bond angels decreased from 105.5120° to95.3750°; total dipole moment is increased from 0.0013 to 9.8242 Debye and the energy gap is decreased from 14.2929 to 6.1591eV. In addition, ESP results are indicated that the electro-negativity of the studied model molecules is increased upon substitution. The change in these calculated physical parameters reflects the reactivity of PVD.

Semiempirical QM/MM calculations reveal a step-wise proton transfer and an unusual thiolate pocket in the mechanism of the unique arylpropionate racemase AMDase G74C

Semiempirical calculations on the mechanism of the arylpropionate racemase AMDase G74C reveal a step-wise mechanism involving a planar-enedionate intermediate.

Adsorption and photocatalytic splitting of water on graphitic carbon nitride: a combined first principles and semiempirical study

Water adsorption on graphitic carbon nitride is studied by means of first principles and semiempirical calculations. Using a thermodynamic model, the photocatalytic water oxidation reaction is found to be hindered by a very large overpotential.