This work focuses on new materials based on the addition of zinc as specifically metal centers for the capture of NO2 gas with DFT calculations. This study aims at the synthesis and the spectroscopic characterizations of the free base meso-tetrakis-,(3,4,5trimethoxyphenyl)porphyrin (H2TTMP) (I), meso tetrakis(3,4,5trimethoxyphenyl) porphyrinato)zinc(II) complex [Zn(TTMP)] (II) and the (4-cyanopyridine) meso-tetrakis - (3,4,5-trimethoxyphenyl) porphyrinato)zinc(II) [Zn(TTMP)(4-CNpy)] (III). X-ray molecular structure of (III) displays that the crystal lattice of the five-coordinated zinc(II) coordination compound, is made up of two dimensional layers parallel to the [0 0 1] direction sustained by CeH⋯Cg and Cg⋯Cg π inter and intra-molecular interactions. Notably, the presence of voids of 1.2 Å and a grid of 0.7 Å are located between the 2D layers. DFT calculations on the three porphyrin derivatives were carried out and results indicated an agreement with both IR and UV-vis experimental data. The adsorption behaviors of the toxic NO2 gas molecules on the porphyrin derivatives were investigated using first-principles density functional theory. Based on the MEP of (I)–(III) molecules and the MEP of NO2 and the calculation of the adsorption energies, we suggest that compound (II) has the best attraction. More importantly, after NO2 chemi-sorption on porphyrin derivatives, a remarkable red-shift is observed in the optical spectra, especially for II/NO2 complex, thus offering a good index to detect the binding of NO2. The optical spectra can therefore be used to detect the presence of NO2 and porphyrin derivatives indicate appropriate properties to establish good NO2 sensors.