Substitution effects on neutral and protonated pyridine derivatives along the periodic table
A theoretical study of the monosubstitution effects of all atoms of the second and third rows of the periodic table on the α, β and γ positions of neutral and protonated pyridine has been carried out by means of B3LYP/6-31 + G(d,p) DFT calculations. The geometric and electronic properties, calculated using the Atoms in Molecules methodology, and the electrostatic potential have been analysed. Concurrently, three separate aromaticity indexes (NICS(0), NICS(1) and HOMA) have been evaluated and compared to the above results. Furthermore, the effect of protonation on these parameters has been investigated. A comparison with analogous results for benzene derivatives has also been carried out.