Assessment of the KID Procedure on a Mo–oxo Complex, an Open–Shell System

The KID (Koopmans in DFT) procedure usually applies in organic molecules of the closed–shell type. We used the KID procedure in an open–shell system for the first time to choose the most suitable density functional to compute global and local reactivity descriptors coming from the Conceptual Density–Functional Theory. From a set of 18 density functionals spread from the second until the fourth rung of the Jacob’s ladder: BP86, B97-D, BLYP, CAM-B3LYP, M06-L, M11-L, MN12-L, B3LYP, PBE0, N12-SX, M06-2X, M11, MN12-SX, CAM-B3LYP, LC-ωHPBE, ωB97X-D, APFD, MN15 and MN15-L, we concluded that CAM-B3LYP provides the best outcome.

Theoretical investigation of the molecular structure and molecular docking of naratriptan

In this work, a computational chemical study of the naratriptan was carried out at the X/DGDZVP (where X = B3LYP, M06, M06L and ?B97XD) level of theory, the results suggest the existence of two possible conformers in the aqueous phase. The evaluation of the global and local reactivity descriptors indicates that both conformers show the same chemical behaviour. The docking studies reveal that both conformers bind to TYR359 residue of the 5HT1B receptor. Also, the first conformer binds to the receptor through THR209 and THR213 while the second one through THR209 and SER 212.

Calculation of global and local reactivity descriptors of carbodiimides, a DFT study

Carbodiimides have been widely used for different purposes, such as an intermediary to form peptides bonds and esters, which have generated industrial, organic and biological applications. Diisoproylcarbodiimide (DIC), (3-(dimethylamino) propyl)ethylcarbodiimide (EDC) and N,N′-dicyclohexylcarbodiimide (DCC) are the most common carbodiimides, however, there exist other carbodiimides that are not normally used. Twelve carbodiimides including the above mentioned were chosen to study their chemical reactivity as well as their nucleophilic and electrophilic attack sites. Geometry optimization in gas and solution phases was obtained using Density Functional Theory (DFT) through B3LYP with 6-31G(d) and 6-311[Formula: see text]G(d,p) level. Global and local reactivity descriptors were calculated and analyzed such as chemical hardness, ionization potential, electron affinity, Fukui functions, dual descriptor and hypersoftness. The results obtained for geometrical parameters do not have significant differences for gas and solution phase. The introduction of diffuse functions has great impact in electron affinity, modifying notably the values of reactivity descriptors, but didn’t show qualitative differences, since the results found for both basis set calculations show that Cyanamide or CD1 is the most stable and CD11 present greater reactivity of all studied molecules. Also, the hypersoftness results obtained with 6-31G(d) are in agreement with the general affirmation that carbodiimides are easily attacked by nucleophiles and electrophiles in the central carbon–nitrogen double bond.

Functionalization of single-walled (n,0) carbon and boron nitride nanotubes by carbonyl derivatives (n = 5, 6): a DFT study

By using density functional theory calculations, the chemical functionalization of finite-sized (5,0) and (6,0) carbon nanotubes (CNTs) and boron nitride nanotubes (BNNTs) by different carbonyl derivatives –COX (X = H, CH3, OCH3, OH, and NH2) is studied in terms of geometrical and electronic structure properties. Also, the benefits of local reactivity descriptors is studied to characterize the reactive sites of the external surface of the tubes. These local reactivity descriptors include the electrostatic potential VS(r) and average local ionization energy ĪS(r) on the surfaces of these nanotubes. The estimated ĪS(r) values show that the functionalized CNTs tend to activate the surface toward electrophilic/radical attack. Results show that the chemical functionalization of CNTs leads to the reduction of VS(r) values and therefore enhances the surface reactivity. On the other hand, BNNTs resist chemical functionalization due to the negligible decrease in the VS,min and ĪS,min values. Generally, in contrast to BNNTs, the chemical functionalization of CNTs can considerably improve their surface reactivity. To verify the surface reactivity pattern based on the chosen reactivity descriptors, the reaction energies for the interaction of an H + ion or hydrogen radical with external surface of the functionalized CNTs and BNNTs are calculated. A general feature of all studied systems is that stronger potentials are associated with regions of higher curvature.