Carbon nanotubes functionalized with Zinc(II) phthalocyanines: Effect of the expanded aromatic system and aromatic substituents on the binding energy

[Display omitted] •Phthalocyanines’ π-system expansion strengthens the interaction with carbon nanotubes.•Phthalocyanines attraction to carbon nanotubes increased due to aromatic substituents.•Carbon nanotube/phthalocyanine system sensitivity is higher at expanded aromaticity. As a result of quantum chemical calculations performed using the Self-consistent-charge Density Functional based Tight Binding (SCC-DFTB) method, it was found that the expansion of the aromatic system of zinc phthalocyanine (ZnPc) to the corresponding naphthalocyanine, as well as the introduction of an oxypyrene substituent into the ZnPc molecule, lead to an increase in the binding energy with carbon nanotubes due to additional π-π interaction. Calculations of changes in the quantum conductance of these hybrid compounds during the adsorption of NH3 molecules, performed within the non-equilibrium Green's function (NEGF) approach, showed that such structural changes not only do not lead to a decrease in the sensor response to ammonia, but in many cases contribute to its increase.