Mechanochemical synthesis, linear and nonlinear optical properties of a new oligophenyleneimine with indole terminal moiety for optoelectronic application

A quadrupolar D-pi-A-pi-D oligophenyleneimine with indole moiety as terminal group (OIC-I) obtained by a green method of mechanosynthesis was obtained. The molecular structure of OIC-I was elucidated by FTIR and H1 NMR spectroscopies. DFT and TDDFT studies show possible intramolecular charge transfer (ICT) processes and a hyperpolarizability value that suggest a nonlinear behavior, which was verified by Z-scan technique. The linear optical characterization of OIC-I using UV-Vis spectroscopy and fluorescence in solution and solid state exhibits a bathochromic effect by increasing the polarity of the solvent. According to data obtained by the Z-scan technique, OIC-I could be used as a saturable absorb material, and this feature can be applied in nonlinear signal filtering, optical signal processing, and mode locking devices. OIC-I has attractive linear and nonlinear optical properties, good processability in solution, and thermal stability for its potential application as a saturated absorber in optoelectronic devices.