Hammett correlations of iminic protons and carbons of some chromenone Schiff's bases

The aim of this work is to carry out DFT calculations on some selected chromenone (benzopyranone) Schiff bases which are substituted on the imine nitro-gen by a para substituted phenyl ring or other aromatic groups like 2-thienyl, thiazo-le, oxazole, pyrrole etc.. This ring will bear both electron withdrawing such as NO2, CN, SO3H, COOR, and electron releasing groups such as methyl, OH, OCH3, NMe2 . A density functional theory (DFT) calculations related to optimization energy, NMR chemical shifts of imine hydrogen, hydrogen attached to the number 2 carbon in chromenone pyran ring and carbon chemical shifts of the iminic carbon and num-ber 2 carbon of chromene ring are also carried out. Throughout this research work, various Hammett correlations between che-mical shift values calculated by using Gaussian 03 software and web-based prog-rams like NMR DB and Avogadro and Hammett substituent constants have been established and interpreted.