Synthesis, structural aspects and nonlinear optical properties of novel phthalimide derivatives: theoretical and experimental approach

Novel phthalimides (1, 2, 3) possessing variability of cyclic amines have been synthesized and characterized by analytical and spectroscopic techniques. Phthalimide 1 and 2 crystallized in a triclinic system with space group P; however, an orthorhombic system with a chiral space group of P2(1)2(1)2(1) was observed for 3 possessing piperidine cyclic amine. The hydrogen atoms attached to the central chiral carbon were oriented anti to each other resulting in minimum steric repulsion. The occurrence of C-H center dot center dot center dot O hydrogen bonds in 1, 2, 3 enabled the building of several supramolecular structures. Hyperpolarizability 197.6096 Debye angstrom(2) calculated for 1 was found to be higher than the hyperpolarizabilities, 138.0836 and 165.2521 Debye angstrom(2) measured for 2 and 3, respectively. Subsequently, phthalimides (1, 2, 3) were assessed for second harmonic generation (SHG) response, and a negligible response was recorded for 1 and 2; however, 3 showed a significant response of 14.2 mV. In addition to acentric structure, helical structural motifs identified in 3 could be responsible for its enhanced SHG response. Copyright (c) 2014 John Wiley & Sons, Ltd.