Investigation of the substituted-titanium nanocages using computational chemistry.

We are investigated substitution effects of titanium heteroatoms on band gap, charge and local reactivity of C20-nTin heterofullerenes (n = 1-5), at different levels and basis sets. The C18Ti2-2 nanocage is considered as the most kinetically stable species with the widest band gap of 2.86 eV, in which two carbon atoms are substituted by two Ti atoms in equatorial position, individually. The charges on carbon atoms of C20 are roughly zero, while high positive charge (1.256) on the surface of C19Ti1 prompts this heteofullerene for hydrogen storage. The positive atomic charge on Ti atoms and negative atomic charge on their adjacent C atoms implies that these sites can be influenced more readily by nucleophilic and electrophilic regents, respectively. We examined the usefulness of local reactivity descriptors to predict the reactivity of Ti-C atomic sites on the external surface of the heterofullerenes. The properties determined include Fukui function (F.F.); f (k) and local softness s (k) on the surfaces of the investigated hollow cages. Geometry optimization results reveal that titanium atoms can be comfortably incorporated into the CC network of fullerene. It is most likely associated with the triple-coordination characteristic of titanium atoms, which can well match with the sp2-hybridized carbon bonding structure. According to the values of f (k) and s (k) for the C15Ti5 heterofullerene; the carbon atoms in the cap regions exhibit a different reactivity pattern than those in the equatorial portion of the heterofullerene. The titanium impurity can significantly improve the fullerene's surface reactivity and it allows controlling their surface properties. The band gap of C20-nTin …..(H2)n structures is decreased with increasing n. Hence, C15Ti5 is found as the best hydrogen adsorbent.

Direct selenosulfonylation of unsaturated compounds: a review.

In this review, we have discussed recent developments on the direct selenosulfonylation of unsaturated compounds which lead to the formation of two new carbon-sulfur and carbon-selenium bonds in a single operation. The reactions were classified based on the type of starting unsaturated compound and product. Thus, the review is divided into three major sections. The first describes the current literature on selenosulfonylation of alkenes. The second section covers the available literature on selenosulfonylation of alkynes. The third focuses exclusively on selenosulfonylation of allenes.

DFT calculations, structural analysis, solvent effects, and non-covalent interaction study on the para-aminosalicylic acid complex as a tuberculosis drug: AIM, NBO, and NMR analyses.

In this study, the effect of non-covalent interactions on the para-aminosalicylic acid complex is explored using density functional theory (DFT) in the gas phase and the solution. Our findings exhibit that the achieved binding energies considerably change on going from the gas phase to the solution. Based on the obtained results, the absolute value of the binding energy of the complex in the polar solvents is lower than the non-polar ones while in the gas phase it is higher than the solution. The atoms in molecules (AIM) and the natural bond orbital (NBO) analyses are applied to estimate the topological properties and the charge transfer during complexation, respectively. The results indicate that the presence of the cation-π interaction increases the strength of the intramolecular hydrogen bond in the studied complex. Finally, the various electronic descriptors such as energy gap, hardness, softness, and electronic chemical potential are investigated to gain further insight into these interactions. According to the achieved results, the high energy gap of the complex in the water solvent indicates high chemical stability and low reactivity compared to the others. On the other hand, the most reactive as well as the softest complex belongs to the gas phase.

Theoretical investigation of the titanium-nitrogen heterofullerenes evolved from the smallest fullerene.

In this survey, we are performed kinetic stability, global reactivity, atomic polar tensor (APT) charge and counter plots of Ti-N heterofullerenes developed from C20 fullerene with the molecular formula of C20-2nTinNn (n = 1-8), at B3PW91/6-311+G∗ level of theory. Also, we are investigated substituent effect of titanium and nitrogen heteroatoms on deuterium adsorption of the heterofullerenes according to density functional theory (DFT). Substituting of Ti-N units with various topology in the cap or equatorial position of heterofullerenes, changes significantly their electronic properties and causes different frontier molecular orbital energy separation (ΔEHOMO-LUMO). Hence, C18Ti1N1 and C10Ti5N5 are found as the best insulated species, while C12Ti4N4 and C4Ti8N8 are considered as the strongest conductive nanocage. Also, C14Ti3N3 cage shows the highest positive APT charge on Ti atom (+1.357, +1.053), while C12Ti4N4 cage shows the lowest positive APT charge on Ti atom (+0.031, -0.292). Accordingly, C14Ti3N3, and C12Ti4N4 exhibit the lowest, and the highest global electrophilicity; ω of 2.58, and 7.01 eV, respectively. As six D2 molecules are approached the C14Ti3N3 heterofullerene, its ΔEHOMO-LUMO (Eg) is increased from 1.29 eV in C14Ti3N3 heterofullerene to 2.11 eV in D2/C14Ti3N3 complex (∼+63.57%) indicating high sensitivity of it to adsorption of six D2 molecules through an exothermic process. As sixteen D2 molecules approaches the C4Ti8N8 nanocage, its Eg reduces from 0.97 to 0.73 eV (∼-24.74%) indicating high electrical conductivity of D2/C4Ti8N8 complex. Therefore, C4Ti8N8 as hopeful sensor, can be generate electrical signals when the D2 molecules approach.

Methods for Direct Reductive N-Methylation of Nitro Compounds.

Direct reductive N-methylation of inexpensive and readily available nitro compounds as raw material feedstocks is more attractive and straightforward compared with conventional N-methylation of amines to prepare biologically and pharmaceutically important N-methylated amine derivatives. This strategy for synthesis of N-methylamines avoids prepreparation of NH-free amines and therefore significantly shortens the separation and purification steps. In recent years, numerous methylating agents and catalytic systems have been reported for this appealing transformation. Thus, it is an appropriate time to summarize such advances. This review elaborates on the most important discoveries and advances in this research arena, with special emphasis on the mechanistic aspect of reactions that may provide new insights into catalyst improvement.

Hydroxysulfonylation of alkenes: an update.

The direct difunctionalization of inexpensive and widely available alkenes has been recognized as a strong and straightforward tool for the rapid fabrication of complex molecules and pharmaceutical targets by introducing two different functional groups on adjacent carbon atoms of common alkene moieties in a single operation. This synthetic strategy avoids the purification and isolation of the intermediates and thus makes synthetic schemes shorter, simpler and cleaner. In this family of reactions, the hydroxysulfonylation of alkenes has emerged as an increasingly promising strategy for the synthesis of ß-hydroxysulfones, which are found in many biologically important molecules and widespread applications in organic synthesis. The objective of this review is to illustrate the advancements in the field of hydroxysulfonylation of alkenes with special emphasis on the mechanistic details of the reaction pathways.