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 Pī; however, an orthorhombic system with a chiral space group of P212121 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···O hydrogen bonds in 1, 2, 3 enabled the building of several supramolecular structures. Hyperpolarizability 197.6096 Debye Å2 calculated for 1 was found to be higher than the hyperpolarizabilities, 138.0836 and 165.2521 Debye Å2 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 © 2014 John Wiley & Sons, Ltd. Novel phthalimides have been synthesized, characterized and investigated for structural features and nonlinear optical applications.