Abstract
The present study reports the synthesis and characterization of 2,2'-(diazene-1,2-diylbis(4,1-phenylene))bis(6-(butylamino)-1H-benzo Idelisoquinoline-1,3(2 H)-dione) (4) using a dual approach consisting of experimental and computational techniques. The indigenously synthesized compound 4 is successfully characterized using UV-vis, fluorescence, FT-IR, and H-1-MNR techniques. The experimental absorption spectra were observed in ethanol solvent at 399 nm and fluorescence emission bands were observed at 550 nm at an excitation wavelength of 400 nm. The compound 4 shows higher thermal stability. From computational point of view, the maximum absorption and emission wavelengths are observed around 377 and 510 nm, respectively, using time-dependent density functional theory (TD-DFT) methods. The average third-order NLO polarizability of compound 4 is calculated to be 407.20 x 10(-36) esu, which is about 53 times larger than the y amplitude of para-nitroaniline pNA (a prototype NLO molecule). Additionally, we have also quantum chemically considered further derivatives of parent system 4 in the form of 4a, 4b and 4c to study the structure NLO property relationships. For derivative compounds 4a, 4b and 4c, their calculated gamma amplitudes are found to be 239.97 x 10(-36), 193.66 x 10(-36), 198.59 x 10(-36) esu, respectively, which illustrate the significant effect of terminal donor/acceptor groups on the NLO response of parent compound 4. Additionally, TD-DFT calculations showed that the largest NLO response in compound 4 is due to its lower transition energy and larger oscillator strength as compared to other systems. It is believed that the present study will highlight the importance of our newly synthesized compound 4 and its derivatives owing to their good NLO response properties.