paper57

Study of Noncovalent Interactions of End-Caped

Sulfur-Doped Carbon Nanotubes Using DFT,

QTAIM, NBO and NCI Calculations

Kayvan Saadat, Hossein Tavakol

Structural chemistry, accepted

ABSTRACT

In the current study, the interactions of carbon nanotube (CNT) and sulfur-doped carbon

nanotubes (SCNTs) with methanol, methanethiol, water and dihydrogen sulfide at on-body and

dead-end positions of nanotubes have been studied. Interaction energies in the gas and solvent

(via PCM model) were calculated using density functional theory (DFT) calculations. Atomic

charges, interaction energies, electron densities and their Laplacians at bond critical points have

been calculated. Moreover, non-covalent interaction isosurfaces have been visualized using NCI

index calculations. Interactions in gaseous phase were more favorable than those in solvent phase

and among considered solvents (benzene, chloroform and cyclohexane), cyclohexane showed the

most preferred interactions. In addition, oxygen-bearing molecules (methanol and water) showed

more favorable interactions comparing with sulfur-bearing ones. NBO analyses revealed the

stronger donor-acceptor interactions with methanol and methanethiol. QTAIM calculation results

indicated the reasonable electron densities at BCPs and the Laplacians of electron densities

showed ionic-like (closed shell) interactions. Moreover, isosurfaces of these interactions were

also studied to depict the interaction surfaces and DOS plots for SCNTs were obtained to define

their HOMO-LUMO levels and electric conduction properties. The increasing of the global

softness and decreasing of total hardness was resulted by sulfur-doping of nanotubes, which

causes the hetero-doped nanotubes to become less electrophilic species.

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