The optimized structures of studied compounds 23-28 are non planner with the two phenyl at C3 and C9 are out of the molecular plane of thiazolo[3,2-a]pyridine as indicated from a dihedral angles of 710 and 1160 respectively, using DFT-B3LYP method with 6-311G(d,p) as basis set. The natural bonding orbital (NBO) analysis of the parent molecule 23 have been analyzed in terms of the hybridization ...