Molecular modeling of phenothiazine derivatives: self-assembling properties.

This study aims to present a detailed theoretical investigation of noncovalent intermolecular interactions between different π-π stacking phenothiazine derivatives and between different alkane chains varying from propane to decane. Second-order Møller-Plesset perturbation (MP2), coupled cluster (CC), and density functional (DFT) theories were the quantum chemistry methods used in our calculation. For MP2 and CC methods, the density-fitting and local approximations were taken into account, while in the case of DFT, the M06 and M06-2x hybrid meta-GGA exchange-correlation functionals as well as the semiempirical correction to the DFT functional for dispersion (BLYP-D) was considered. The results obtained with the aforementioned methods were compared with the potential energy curve given by the DF-SCSN-LMP2 theory considered as benchmark. For all these calculations, the correlation-consistent basis sets of cc-pVNZ (where N = D, T, Q) were used. In addition, potential energy curves built using the semiempirical PM6-D2 and the MM3 molecular force field methods were also compared with the benchmark curve and their efficiency was discussed. As the next step, several geometry conformations were investigated for both phenothiazine derivatives and alkane chain dimers. It was found that the conformational stability of these molecular systems is exclusively given by the dispersion-type electron correlation effects. The density functional tight-binding (DFTB) method applied for dimer structures was compared with the results obtained by the higher level local perturbation theory method, and based on these conclusions larger phenothiazine derivative oligomers structures were investigated. Finally, the optimal configuration of the complex molecular systems built by phenothiazine derivative, alkane chain fragments, and thiol groups was determined, and their self-assembling properties were discussed.