Synthesis, characterization and evaluation of the photophysical and nonlinear optical behaviour of novel 4-substituted arylidene-2-[5-(2,6-dichlorophenyl)-3-methyl-1,2-oxazol-4-yl]-1,3-oxazol-5-ones

•Amongst the oxazolyloxazolones the dialkylamino substituted derivatives exhibited the highest λmax and λem in DMF.•The nonlinear refractive index is found to be negative and its magnitude is of the order of 10−11 esu.•The molecular two photon absorption cross-sections are of the order of 10−46 cm4 s/photon.•Values of two photon absorption cross-section are nearly two orders of magnitude larger than of Rhodamine 6G.•Molecules with –NR2 substituents exhibited better optical limiting behaviour.

Five new 4-substituted arylidene-2-[5-(2,6-dichlorophenyl)-3-methyl-1,2-oxazol-4-yl]-1,3-oxazol-5-ones have been designed and synthesized in order to study their third-order nonlinear optical properties. These novel compounds were characterized by advanced spectroscopic techniques (IR, 1H, 13C NMR, ESI-MS spectroscopy and elemental analyses). In addition, the evaluation of absorption and emission wavelengths of the new 5-oxazolone derivatives was carried out in seven different solvents of varying polarity, which showed intense absorption maxima at 350–480 nm and emission maxima at 390–535 nm respectively. The third-order nonlinear optical properties of the target molecules have been investigated in N,N-dimethylformamide using a single beam Z-scan technique with nanosecond laser pulses at 532 nm. The nonlinear refractive index, nonlinear absorption coefficient, magnitude of third-order susceptibility and molecular two photon absorption cross-sections have been determined. All of the compounds showed excellent optical limiting behaviour at 532 nm, with the best optical limiting behaviour observed with strong electron donor [dimethyl and N,N-diethyl amino] substituents.

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