DFT calculations of the tautomerization and NLO properties of 5-amino-7-(pyrrolidin-1-yl)-2,4,4-trimethyl-1,4-dihydro-1,6-naphthyridine-8-carbonitrile (APNC)

Amine-imine tautomerization in 5-amino-7-(pyrrolidin-1-yl)-2,4,4-trimethyl-1,4-dihydro-1,6-naphthyridine-8-carbonitrile (APNC) has been studied using the B3LYP, CAM-B3LYP and ωB97XD with 6-311++G(d,p) basis set. Optimum molecular geometries, electronic properties, energetics and electronic densities of these systems have been discussed and compared with the available experimental data. Investigation reveals that one tautomer (the amine tautomer) dominates the gas phase. The photochromic properties of APNC and its two imine tautomers have been studied at the elected DFT-functionals and basis set. The interconversion A1 to I2/I3 is predicted to occur photochemically. The NLO properties were also evaluated and discussed.