Meso-tetrakis(3,4,5-trimethoxyphenyl)porphyrin derivatives: Synthesis, spectroscopic characterizations and adsorption of NO2

Abstract This work focuses on new materials based on the addition of zinc as specifically metal centers for the capture of NO 2 gas with DFT calculations. This study aims at the synthesis and the spectroscopic characterizations of the free base meso -tetrakis-,(3,4,5trimethoxyphenyl)porphyrin (H 2 TTMP) ( 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 [001] direction sustained by C __ H … Cg and Cg … Cg π inter and intra-molecular interactions. Notably, the presence of voids of 1.2 A and a grid of 0.7 A 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 NO 2 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 NO 2 and the calculation of the adsorption energies, we suggest that compound ( II ) has the best attraction. More importantly, after NO 2 chemi-sorption on porphyrin derivatives, a remarkable red-shift is observed in the optical spectra, especially for II/NO 2 complex, thus offering a good index to detect the binding of NO 2 . The optical spectra can therefore be used to detect the presence of NO 2 and porphyrin derivatives indicate appropriate properties to establish good NO 2 sensors.