Abstract

The interaction of anticancer drug Sn(CH₃)₂(N-acetyl-L-cysteinate), that is called (N-acetyl-L-cysteinato-O,S) dimethyl tin(IV),  with single walled  carbon nanotube (SWCNT) is investigated by Quantum chemical ab initio calculations at HF/(LanL2DZ+STO-3G) and HF/(LanL2DZ+6-31G) levels in gas phase and solution. The solvent effect is taken into account via the self-consistent reaction field (SCRF) method. Carbon nanotubes can act as a suitable drug delivery vehicle for internalization, transportation and translocation of Sn(CH₃)₂(N-acetyl-L-cysteinate) within biological systems. Thermodynamical analysis indicates that the relative energies (ΔE), enthalpies (ΔH) and free Gibbs energies (ΔG) are negative for Sn(CH₃)₂(N-acetyl-L-cysteinate)-CNT system, but the calculated entropies (ΔS) are positive, suggesting thermodynamic favorability for covalent attachment of Sn(CH₃)₂(N-acetyl-L-cysteinate) into carbon nanotube. Also, the results show that with increasing dielectric constant of solvent, the stability of Sn(CH₃)₂(N-acetyl-L-cysteinate)-CNT complex decreases. Furthermore, anisotropic chemical shift tensor (Δσ), total atomic charge and asymmetry parameter (η) have been calculated using the gauge-including atomic orbital (GIAO) method, results being compared with CGST data. From the nuclear magnetic resonance (NMR) calculations, it can be seen that the NMR (Δσ_, η) parameters at the sites of nitrogen and oxygen, as well as C-2 and C-3 nuclei are significantly influenced by intermolecular hydrogen-bonding interactions, but the quantity at the site of S-27 is influenced by nonspecific solute-solvent interaction, such as polarisability/polarity.

Key words: Sn(CH₃)₂(N-acetyl-L-cysteinate), nuclear magnetic resonance (NMR) parameters, single walled  nanotube (SWNT), solvent.