Theoretical studies on substituent effects of meta-substituted pyridines

ab initio molecular orbital calculation is performed to estimate the substituent effects for meta-substituted pyridines. Electrostatic potentials are obtained from ab initio wavefunctions of the optimized structures for the meta-substituted pyridines. Electrostatic potentials are shown to be minimum at nitrogen atom of pyridines. The potential minima are good correlated with the substituent constants, σm and with the ΔpKa, respectively. It is found that the electrostatic potential minima can be used as a useful measure of substituent effects