Density Functional Theory Reactivity Studies on X3N@C80 (X = Sc, Gd, Lu) Fullerenes

Density functional theory studies have been performed to reveal the reactivity of the sites in Sc3N@C80, Gd3N@C80 and Lu3N@C80 endohedral fullerenes. The condensed Fukui functions have been calculated using Mulliken atomic charges. The calculations show that the carbon atom sites are in direct contact with the endohedral cluster favourable nucleophilic attack. Similarly, the carbon atoms which are away from the direct bonding with the cluster are favourable for the electrophilic attack. This is also confirmed from the charge transfer analysis. It is noted that the spin multiplicity decides the reactivity sites and stability of the Gd3N@C80 system. The HOMO-LUMO gap value indicates that Gd3N@C80 with S = 7 is stable than the S = 21 system. Finally, present studies indicate that the charge transfer between the C80 cage and X3N plays a major role to determine the reactivity of the sites in the C80 cage.

DFT investigations on arylsulphonyl pyrazole derivatives as potential ligands of selected kinases

Using the density functional theory (DFT) formalism, we have investigated the properties of some arylsulphonyl indazole derivatives that we studied previously for their biological activity and susceptibility to interactions of azoles. This study includes the following physicochemical properties of these derivatives: electronegativity and polarisability (Mulliken charges, adjusted charge partitioning, and iterative-adjusted charge partitioning approaches); free energy of solvation (solvation model based on density model and M062X functional); highest occupied molecular orbital (HOMO)–lowest occupied molecular orbital (LUMO) gap together with the corresponding condensed Fukui functions, time-dependent DFT along with the UV spectra simulations using B3LYP, CAM-B3LYP, MPW1PW91, and WB97XD functionals, as well as linear response polarisable continuum model; and estimation of global chemical reactivity descriptors, particularly the chemical hardness factor. The charges on pyrrolic and pyridinic nitrogen (the latter one in the quinolone ring of compound 8, as well as condensed Fukui functions) reveal a significant role of these atoms in potential interactions of azole ligand–protein binding pocket. The lowest negative value of free energy of solvation can be attributed to carbazole 6, whereas pyrazole 7 has the least negative value of this energy. Moreover, the HOMO–LUMO gap and chemical hardness show that carbazole 6 and indole 5 exist as soft molecules, while fused pyrazole 7 has hard character.

A DFT study of the chemical reactivity of thiobencarb and its oxidized derivatives in aqueous phase

In the present work, the global and local reactivity of S-(4-chlorobenzyl)- N,N-diethylthiocarbamate (TB) and its oxidized derivatives (sulfone (TBSu) and sulfoxide (TBS) were analyzed. In addition, the chemical reactivities of the dechlorinated forms of TB (DTB), TBSu (DTBSu) and TBS (DTBS) were studied. The calculations were performed at the wB97XD/6- -311++G(2d,2p) level of theory in the aqueous phase. The condensed Fukui functions indicated that for TB and DTB, the most preferred sites for donating electron in a reaction are located on the S and N atoms, while the most reactive sites for accepting electrons are associated with the aromatic ring (AR). For TBS and DTBS, the more reactive sites are located on AR, S and AR for nucleophilic, electrophilic and free radical attacks, respectively. In the case of TBSu and DTBSu, the results showed AR to be the more reactive zone for the three kinds of attacks. These last results suggest that cleavage of the C?S bond in TB, TBS and their dechlorinated forms is favored by electrophilic attacks. Additionally, the obtained results suggest that in TB, it is plausible that the cleavage of the C?N is favored on attack of this molecule by electrophiles.

Experimental and Theoretical Investigation of the Reaction of Secondary Amines with Maleic Anhydride

The reaction of secondary amines, namely 1-methylpiperazine, pyrrolidine, morpholine, 2-methylpiperidine, and diethylamine, with maleic anhydride has been investigated experimentally and theoretically at the DFT level. Under kinetic control, i.e. at −78°C or −15°C, amines add across the C=O functionality exclusively and the initially formed addition products isomerize to the corresponding N-substituted maleimic acid derivatives. In contrast to the acyclic α,β-unsaturated carbonyl compounds, amine does not add across the C=C functionality in maleic anhydride even under thermodynamic control. This behaviour of maleic anhydride can be rationalized on the basis of the local condensed Fukui functions, which reveal that the carbonyl carbon atoms in maleic anhydride are much harder than in an acyclic α,β-unsaturated carbonyl compound, such as acrolein. This prompts the amines to attack the carbonyl group in maleic anhydride exclusively.